t^tTii'ttti-rririiatiiTtfiisrihv^. ii \ '-•*«385>*i^ ^SS^^^ mamimmettf mm\t\\xMumtumm.vMH[.t:iu^^u.mLV UNIVERiSITY OF PITTSBURGH DoM. Jjarlington .Alemorial Library THE DESCEE'T OF MAN, SELECTION IN RELATION TO SEX. THE DESCEN^T OF MAI^, AND SELECTION IN RELATION TO SEX. BY CHAELES DAEWIN, M. A. FELLOW OF THE KOYAL SOCIETY, ETC. m\t^ lllastratiflits; NEW EDITION, REVISED AND AUGMENTED. COilPLETE IN ONE VOLUME. NEW YOKE : D. APPLETON AND COMPANY, 549 AND 551 BROADWAY. 1875. X. .^-3- ^ PEEFACE TO THE SECOND EDITION. During the successive reprints of the first edition of this work, published in 1871, I was able to introduce several important corrections; and now that more time has elapsed, I have endeavoured to profit by the fiery ordeal through which the book has passed, and have taken advantage of all the criticisms which seem to me sound. I am also greatly indebted to a large number of correspondents for the communication of a surprising number of new facts and remarks. These have been so numerous, that I have been able to use only the more important ones ; and of these, as well as of the more important corrections, I will append a list. Some new illustrations have been introduced, and four of the old drawings have been replaced by better ones, done from life by Mr. T. W. Wood. I must especially call attention to some observations which I owe to the kindness of Prof. Huxley (given as a supplement at the end of Part I.), on the nature of the differences between the brains of man and the higher apes. I have been particularly glad to give these obser- vations, because during the last few years several memoirs on the subject have appeared on the Continent, and their importance has been, in some cases, greatly exaggerated by popular writers. I may take this opportunity of remarking that my critics frequently assume that I attribute all changes of corporeal structure and mental power exclusively to the natural selection of such variations as are often called spontaneous; whereas, even in the first edition of the ' Origin of Species,' I distinctly stated that great weight must be attributed to the inherited effects of use and disuse, with respect both to the body and mind. I also attributed some amount of modification to the direct and prolonged action cf changed conditions of life. Some aUowance. too, must be made for occasional reversions of vi Preface to the Second Edition. structure ; nor must we forget what I liaTe called " correlated *' growth, meaning, thereby, that various parts of the organisation are in some unknown manner so connected, that when one part varies, so do others; and if variations in the one are accu- mulated by selection, other parts will be modified. Again, it has been said by several critics, that when I found that many details of structure in man could not be explained through natural selection, I invented sexual selection ; I gave, however, a tolerably clear sketch of this principle in the first edition ol the ' Origin of Species,' and I there stated that it was applicable to man. This subject of sexual selection has been treated at full length in the present work, simply because an opportunity was here first afforded me. I have been struck with the likeness oi many of the half-favourable criticisms on sexual selection, with those which appeared at first on natural selection; such as, that it would exj)lain some few details, but certainly was not apphcable to the extent to which I have employed it. My conviction of the power of sexual selection remains unshaken ; but it is probable, or almost certain, that several of my con- clusions will hereafter be found erroneous ; this can hardly fail to be the case in the first treatment of a subject. When naturalists have become familiar with the jdea of sexual selection^ it will, as I believe, be much more largely accepted; and it has already been fully and favourably received by several cajDable judges. Down, Beckexham, Kent, September 1874. TABLE PEINCIPAL ADDITIONS AND COEEECTIONS TO THE PRESENT EDITION. First Edition. Trcsent Edition. Vol. I. Page 22 26 27, note. 29 32, note. 40 42 44 47 50 53 58 64 78 79 81 90, note. 91 94 97 112 122 124, note. 125, note. 128-9 146 Page 15-17 19 20, note. 23 24, note, 70 71 72 3 75 80 83 88-9 92 104 104 105-6 ril2-113,] \ note. ] 114 117, note. 120, note. 28 35-G 39, note. 3G-8, note. 41-2 55, note. f Discussion on the rudimentary points in the \ human ear revised. Cases of men born with hairy bodies. Muntegazza on the last molar tooth in man. Tiie rudiments of a tail in man. IBianconi on homologous structures, as ex- plained by adaptation on mcciianieal principles. Intelligence in a biiboon. Sense of humour in dogs. (Further facts on imitation in man and \ animals. Reasoning power in the lower animals. Acquisition of experience by animals. Power of abstraction in animals. JPower of forming concepts in relation to \ language. . , , (Pleasure from certain sounds, colours, and \ forms. Fidelity in (he elephant. Galton on gregariousncss of cattle. Parental atfection. Persistence of enmity and hatred. ^Nature and strength of shame, regret, and \ remorse. Snicide amongst savages. The motives of conduct. Selection, as applied to primeval man. Resemblances between idiots and animals. Division of the malar bone. Supernumerary mamnuo and digits. Further cases of mutcles projier to aninials appiaring in man. Broca : average oftpacity of slaill diniinislied by the preservation of the inferior members of society. viii Table of the Principal A dditions and First Edition. Vol. Page 149 150 169 180 193 208. note. 209 239 245 250 256 275-6 290 Present Edition. Page 57 58-9 134-5 143 151 161, note. 163 188-190 195-6 199-206 209-210 224-5 235 301 314 243-4 254 315 255-6 327 264 338 272 339 273 345 277 349 280 350 281 351 282 854 284-5 359 288, note 366 292-3 387 308 397 315 401 319 412 324-5 117 326 I Belt on advantages to man from his hair- \ lessness. (Disappearance of the tail in man and certain \ monkeys. ("Injurious forms of selection in civilised \ nations. (Indolence of man, when free from a struggle \ for existence, jGorilla protecting himself from rain with his \ hands. Hermaphroditism in fish. Eudimentary mammae in male mammals. (Changed conditions lessen fertility and cause \ ill-health amongst savages. JDarkness of skin a protection against the \ sun. jNote by Professor Huxley on the develop- \ ment of the brain in man and apes. (Special organs of male parasitic worms for \ holding the female. Greater variability of male than female; direct action of the environment in causing differences between the sexes. Period of development of protuberances on birds' htads determines their trans- mission to one or both sexes. Causes of excess of male births. Proportion of the sexes in the bee family. (Excess of males perhaps sometimes deter- ( mined by selection. Bright colours of lowly organised animals. Sexual selection amongst spiders. Cause of smallness of male spiders. Use of phosphorescence of the glow-worm. The humming noises of flies. Use of bright colours to Hemiptera (bugs). Musical apparatus of Homoptera. (Development of stridulating apparatus in \ Orthoptera. (Hermann Miiller on sexual differences of \ bees. Sounds produced by moths. Display of beauty by butterflies. (Female butterflies, taking the more active \ part in courtship, brighter than their males. (Further cases of mimicry in butterflies and \ moths. (Cause of bright and diversified colours of \ caterpillars. Corrections to tJie Present Edition. IX First Edition. Vol. II. Pape 2 M 23 26 30 82 3G 72 91 108 118 120 124 147-150 152 157 232 ^47 248 256 260 266 286 299 316 337 356 359 et seq. 373 380 rropont Kdition. Page 33 i 341 347 349 352 353 357 383 398 411 417 419 423 438-441 443 446 495-6 505 506 513-514 516 521 534 542-3 556 572 586 588 et seq. 59S-9 603 Brush-liko scales of male Mall(.)tu.s. |Furtlier facts on courtship of tishcs, and the \ spawning of Macropus. Dufosse' on the sounds made by fl.slics. Belt on a frog protected by bright colouring. Further facts on mental powers of snakes. Sounds produced by snakes ; the rattlesnake. Cond)ats of Chameleons. Marshall on protuberances on birds' heads. ^Further facts on display by the Argus \ pheasant. Attachment between paired birds. Female pigeon rejecting certain males. jAlbino birds not finding partners, in a state \ of nature. Direct action of climate on birds' colours. jFurther facts on the ocelli in the Argus \ pheasant. Display by humming-birds in courtship. jCases with pigeons of colour transmitted to \ one sex alone. I Taste for the beautiful permament enough to allow of sexual selection with the lower animals. I Horns of sheep originally a masculine \ character. Castration afiecting horns of animals. Prong-horned variety of Cervus vir'jimaiius. |Ilelative sizes of male and female whales aud \ seals. Absence of tusks in male miocene pigs. Dobson on sexual differences of bats. Eeekson advantage from peculiar colouring. |Difterence of comj)lexion in men and women \ of an African tribe. Speech subsequent to singing, |Schopenhauer on importance of courtship to \ mankind. ^Revision of discussion on communal marriages \ and promiscuity. |Fower of choice of woman in marriage, \ amongst savages. |Long-continued habit of plucking out hairs \ may produce an inherited cfiect. CONTENTS. Inteoduotion Pages 1-4 PART I. THE DESCENT OR ORIGIN OF MAN. CHAPTER I. The Evidence of the Descent of Man from some Lower Form. PAGE Nature 'of the evidence bearing on the origin of man — Homologous structures in man and the lower animals — IMiscellaneous points of correspondence — Development — Rudimentary structures, muscles, sense-organs, hair, bones, reproductive organs, Arc. — The bearing of these three great classes of facts on the origin of man ........•• ^ CHAPTER 11. On the Manner of Development of Man fkom some Lower Form. Variability of body and mind in man— Inheritance— Causes of variability— Laws of variation the t-ame in man as in the lower animals— Direct action of the conditions of life— Etl'ects of the increased use and disuse of parts— Arrested development— Re- version—Cnrrc luted variation— Rate of Increase — Checks to increase— Natural selection- Man the most dominant animal in tlie world— Im})ortance of his corporeal structure— Tlie causes which have kd to his becoming erect— Consequent clianges of structure— Decrease in size of the canine teeth— Increased size and altered shape of the skull— Nakedness— Absence of a tail- Defenceless condition of man 2G CHAPTER III. Comparison of the Mental Powers of Man and the Lowkr Animals. The difftrence in mental power between the highest ape and the lowest savage, immense— Certain instincts in common— The emotions— Curiosity— Imitation— Att(ntion — Memory— Imagi- nation—Reason— Progressive improvement- Tools and weapons xii Contents. PAGE used by animals — Abstraction, Sell-consciousness — Language — Sense of beauty — Belief in God, spiritual agencies, super- stitions ......... 65 CHAPTEll IV. COMPAKISON OP THE MeNTAL PoWERS OF MaN AND THE LoWER Andials — continued. The moral sense — Fundamental proposition-^The qualities of social animals — Origin of sociability*— Struggle between opposed instincts — Man a social animal — The more endm-ing social in- stincts conquer other less persistent instincts — The social virtues alone regarded by savages — The self-regarding virtues acquired at a later stage of development — The importance of the judg- ment of the members of the same community on conduct — Transmission of moral tendencies — Summary . . 97 CHAPTEK V. On the Development of the Intellectual and Moral Faculties during Primeval and Civilised Times. Advancement of the intellectual powers through natural selec- tion— Importance of imitation — Social and moral faculties — Their development within the limits of the same tribe — Natural selection as affecting civilised nations — Evidence that civilised nations were once barbarous . .... 127 CHAPTER VI. On the Affinities and Genealogy of Man. Position of man in the animal series — The natural system genea- logical— Adaptive characters of slight value — Various small points of resemblance between man and the Quadrumana — Bank of man in the natural system — Birthplace and antiquity of man — Absence of fossil connecting-links — Lower stages in the genealogy of man, as inferred, tirstly from his aiSnities and secondly from his structure — Early androgynous condition of the Vertebrata — Conclusion . . . . . 14G CHAPTER VII. On the Eaces of Man. The nature and value of specific characters — Application to the races of man — Arguments in favour of, and opposed to, ranking the so-called races of man as distinct species — Sub-species — Monogenists and polygenists — Convergence of character — Contents. xiii Numerous points of resemblance in body and mind bet\Ycen the most distinct races of man — The state of man when he lirst spread over the earth — Each race not descended from a single pair — The extinction of races — The formation of races — The eftects of crossing — Slight influence of the direct action of the conditions of life — Slight or no influence of natural selection — Sexual selection ....... 166 PAET II. SEXUAL SELECTION. CHAPTEE VIII. Principles of Sexual Selection. Secondary sexual characters — Sexual selection — Manner of action — Excess of males — Polygamy — The male alone generally modified through sexual selection — Eagerness of the male — Variability of the male — Choice exerted by the female— Sexual compared with natural selection — Inheritance at corresponding periods of life, at corresponding seasons of the year, and as limited by sex — Relations between the several forms of inheri- tance— Causes why one sex and the young are not modititd through sexual selection — Supplement on the proportional num- bers of the two sexes throughout the animal kingdom — The proportion of the sexes in relation to natural selection . . 207 CHAPTER IX. Secondary Sexual Characters in the Lower Classes of THE Animal Kingdom. These characters absent in the lowest classes — Brilliant colours — Mollusca — Annelids— Crustacea, secondary sexual characters strongly developed ; dimorphism; colour; characters not ac- quired before maturity — Spiders, sexual colours of; stridulation by the males — Myriapoda 2G0 CHAPTER X. Secondary Sexual Characters of Insects. Diversified structures possessed by the males for seizing the females— Differences between the sexes, of which the mean- ing is not understood— Difference in size between the sexes — Thysanura — Diptera— llemiptera — Homoptera, musical powers xiv Contents. PAGS possessed by the males alone — Orthoptera, musical instruments of the males, nuicli diversified in structure; pugnacity; colours — Neuroptera sexual differences in colour — Hymenoptera, pug- nacity and colours — Culenptera, colours ; furnished with great horns, apparently as an ornament ; battles ; stridulating organs generally common to both sexes .... 274 CHAPTER XL Insects, continued. — Order Lepidoptera. (butterflies and moths.) Courtship of butterflies — Battles — Ticking noise — Colours common to both sexes, or more brilliant iti the males — Examples — Not due to the direct action of the conditions of life — Colours adapted for protection — Colours of moths — Distday — Perceptive powers of the Lepidoptera — Variability — Causes of the difference in colour between the males and females — Mimicry, female butterflies more brilliantly coloured than the males — Bright colours of caterpillars — Summary and concluding remarks on the secondary sexual characters of insects — Birds and insects compared ........ 307 CHAPTEK XII. Secondary Sexual Charactters of Fishes, Amphibians, and Reptiles. Fishes: Courtship and battles of the males — Larger size of the females — Males, bright colours and ornamental appendages; other strange characters — Colours and appenilages acquired by the males during the breeding-season alone — Fishes with both sexes brilliantly coloured — Protective colours — The less con- spicuous colours of the female cannot be accounted for on the principle of protection — Male fishes building nests, and taking charge of the ova and young. Amphibians: Differences in structure and colour between the sexes — Vocal organs. Rep- tiles : Chelonians — Crocodiles — Snakes, colours m some cases protective — Lizards, battles of — Ornamental appendages — Strange differences in structure between the sexes — Colours — Sexual difterences almost as great as with birds . . 330 CHAPTER XIII. Secondary Sexual Characters of Birds. Sexual differences — Law of battle — Special weapons — Vocal organs — Instrumental music — Love-antics and dances — Deco- rations, permanent and seasonal — Double and single annual moults — Display of ornaments by the males . . 358 Contents. xv CHAPTEK XIV. BiUDS — continued. PAOB Choice exerted by the female — Length of eourtsliip — Unpaired birds — jMental qualities and ta^^te for the beautiful — Preference or antipatliy shewn by tlie female for particular males — Vari- ability of birds — Variations sometimes abrupt — Laws of varia- tion— Formation of ocelli— Gradations of character — Case of Peacock, Argus phea.sant, nnd Uro^ticte . . . 404 CEL\PTER XV. Birds — continued. Discussion as to why the males alone of some species, and both sexes of others are briglilly coloured — On sexually-limited inheritance, as applied to various structures and to brightly- coloured plumage — Nidification in relation to colour — Loss of nuptial plumage during the winter .... 444 CHAPTER XVI. Birds — concluded. The immature plumage in relation to the character of the plumage in both sexes when adult — Six classes of cases — Sexual diflfer- ences between the males of closelj-allied or representative species — The female assuming the characters of the male — Plumage of the young in relation to the summer and winter plumage of the adults — On the increase of beauty in the birds of the woi-ld — Protective colouring — Conspicuously-coloured birds — Novelty appreciated — Summary of the four chapters on birds 463 CHAPTER XVII. Secondary Sexual Characters of Mammals. The law of battle — Special weapons, contined to the males — Cause of absence of weapons in the female — Weapons common to both sexf s, yet primarily acquired by the male — Other uses of such weapons- -Their high importance — Greater size of the male — Means of defence — On the preference sliewn by either sex in the pairing of quadrupeds ...... 500 CHAPTER XVIII. Secondary Sexual Characters of Masimals — continued. Voice — Remarkable sexual peculiarities in seals — Odour — Develop- ment of the hair — Colour of the hair and skin— Anomalous xvi Contents. case of the female being more ornamented than the male — Colour and ornaments due to sexual selection — Colour acquired for the sake of protection — Colour, though common to both sexes, often due to sexual selection — On the disappearance of spots and stripes in adult quadrupeds — On the colours and orna- ments of the Quadrumana — Summary . . . 525 PAET in. SEXUAL SELECTION IN KELATION TO MAN, AND CONCLUSION. CHAPTER XIX. Secondary Sexual Characters op Man. Differences between man and woman — Causes of such differences, and of certain characters common to both sexes — Law of battle — Differences in mental powers, and voice — On the influence of beauty in determining the marriages of mankind — Attention paid by savages to ornaments — Their ideas of beauty in woman — The tendency to exaggerate each natural peculiarity . 556 CHAPTER XX. Secondary Sexual Characters of Man — continued. On the effects of the continued selection of women according to a different standard of beauty in each race — On the causes which interfere with sexual selection in civilised and savage nations — Conditions favourable to sexual selection during primeval times — On the manner of action of sexual selection with man- kind— On the women in savage tribes having some power to choose theix husbands — Absence of hair on the body, and development of the beard — Colour of the skin — Summary . 585 CHAPTER XXI. General Summary and Conclusion. Main conclusion that man is descended from some lower form — Manner of development — Genealogy of man — Intellectual and moral faculties — Sexual selection — Concluding remarks . 603 Index 620 THE DESCENT OF MAN; AND SELECTION IN KELATION TO SEX. INTRODUCTION. The nature of the following work will be best imderstood by a brief account of how it came to be written. During many years I collected notes on the origin or descent of man, without any intention of publishing on the subject, but rather with the determination not to publish, as I thought that I should thus only add to the prejudices against my views. It seemed to me sufficient to indicate, in the first edition of my 'Origin of Species,' that by this work "light would be thrown on the " origin of man and his history ;" and this imphes that man must be included with other organic beings in any general conclusion respecting his manner of appearance on this earth. Now the case wears a wholly different aspect. When a naturalist like Carl Vogt ventures to say in his address as President of the National Institution of Geneva (1869), " pcrsonne, en Europe " au moins, n'ose plus soutenir la creation independante et de " toutes pieces, des especes," it is manifest that at least a largo number of naturalists must admit that species are the modified descendants of other species ; and this especially holds good with the younger and rising naturalists. The greater number accept the agency of natural selection ; though some urge, whether with justice the future must decide, that I have greatly overrated its importance. Of the older and honoured chiefs in natural science, many unfortunately are still opposed to evolution in every form. In consequence of the views now adopted by most naturalists, and which will ultimately, as in every other case, be followed by Introduction. others who are not scientific, I have been led to put together my notes, so as to see how far the general conclusions arrived at in my former works were applicable to man. This seemed all the more desirable, as I had never deliberately applied these views to a species taken singly. When we confine our attention to any one form, we are • dej^rived of the weighty arguments derived from the nature of the affinities which connect together whole groups of organisms— their geographical distribution in past and present times, and their geological succession. The homological structure, embryological development, and rudi- mentary organs of a species remain to be considered, whether it be man or any other animal, to which our attention may be directed ; but these great classes of facts afford, as it appears to me, ample and conclusive evidence in favour of the principle of gradual evolution. The strong support derived from the other arguments should, however, always be kept before the mind. . The sole object of this work is to consider, firstly, whether man, like every other species, is descended from some pre- existing form ; secondly, the manner of his development ; and thirdly, the value of the differences between the so-called races of man. As I shall confine myself to these jDoints, it will not be necessary to describe in detail the differences between the several races— an enormous subject which has been fully discussed in many valuable works. The high antiquity of man has recently been demonstrated by the labours of a host of eminent men, beginning with M. Boucher de Perthes ; and this is the indis- pensable basis for understanding his origin. I shall, therefore, take this conclusion for granted, and may refer my readers to the admirable treatises of Sir Charles Lyell, Sir John Lubbock, and others. Nor shall I have occasion to do more than to allude to the amount of difference between man and the anthropomor- phous apes ;.for Prof. Huxley, in the opinion of most competent judges, has conclusively shewn that, in every visible character man differs less from the higher apes, than these do from the lower members of the same order of Primates. This work contains hardly any original facts in regard to man ; but as the conclusions at which I arrived, after drawing up a rough draft, appeared to me interesting, I thought that they might interest others. It has often and confidently been asserted, that man's origin can never be known : but ignorance more frequently begets confidence than does knowledge : it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science. The conclusion that man is the co-descendant with other species of some ancient, lower, and extinct form, is not in Introductioji. any degree new. Lamarck long ago came to this conclusion, which has lately been maintained by several eminent naturalists and philosophers ; for instance, by Wallace, Hnxley, Lyell, Vogt, Lubbock, Biichner, Rolle, &c.,^ and especially by Hackel. Tlj^s last naturalist, besides his great work, * Gencrclle Morphologic ' (1866), has recently (1868, with a second edit, in 1870), pub- lished his * Naturliche Schopfungsgeschichte,' in which he fully discusses the genealogy of man. If this work had appeared before my essay had been written, I should probably never have completed it. Almost all the conclusions at which I have arrived I find confirmed by this naturalist, whose knowledge on many points is much fuller than mine. Wherever I have added any fact or view from Prof. Hiickel's writings, I give his autho- rity in the text ; other statements I leave as they originally stood in my manuscript, occasionally giving in the foot-notes references to his works, as a confirmation of the more doubtful or interesting points. During many years it has seemed to me highly probable that sexual selection has played an important part in differentiating the races of man ; but in my ' Origin of Species ' (first edition, p. 199) I contented myself by merely alluding to this belief. "When I came to apply this view to man, I found it indispensable to treat the whole subject in full detail.^ Consequently the second part of the present work, treating of sexual selection, has ex- tended to an inordinate length, compared with the first part; but this could not be avoided. I had intended adding to the present volumes an essay on the expression of the various emotions byman and the lower animals. My attention was called to this subject many years ago by Sir Charles Bell's admirable work. This illustrious anatomist ' As the works of the first-named JSat.,' Modena, ]8(37, p. 81) a very authors are so well known, I need curious paper on rudimentary cha- not give the titles; but as those of racters, as bearing on the ori'^in of the latter are less well known in man. Another work has (1869) England, I will give them : — ' Sechs been published by Dr. Francesco Vorlesungen iiber die Darwin'sche Barrago, bearing in Italian the title Theorie:' zweite Auflage, 1868, von of "Man, made in the image of God, Dr. L. Buchner; translated into " was also made in the image of the French under the title 'Conferences "ape." sur la Theorie Darwinienne,' 1869. '•^ Prof. Hiickel was the only *Der Mensch, im Lichte der Dar- author who, at the time when this win'sche Lehre,' 1865, von Dr. F. work first appeared, had di.-,cussed Rolle. I will not attempt to give the subject of sexual selection, and references to all the authors who had seen its full importance, since have taken the same side of the the publication of the 'Origin '; and question. Thus G. Canestrini has this he did in a very able manner io published (' Annuario della Soc. d. his various works. Introduction. maintains that man is endowed with certain muscles solely for the sake of expressing his emotions. As this view is obviously opposed to the belief that man is descended from some other and l4)wer form, it was necessary for me to consider it. I likewise wished to ascertain how far the emotions are expressed in the same manner by the different races of man. But owing to. the length of the present work, I have thought it better to reser\^e my essay for separate publication. ( 5 ) Part I. THE DESCENT OR ORIGIN OF MAN. CHAPTER I. The Evidence of the Descent of Man from some Lower Form. Nature of the evidence bearing on the origin of man — Homologous structures in man and the lower animals — Miscellaneous points of correspondence — Development — Rudimentary structures, muscles, sense- organs, hair, bones, reproductive organs, &c. — The bearing of these three great classes of tacts on the origin of man. He who wishes to decide whether man is the modified descendant of some. pre-existing form, would probably first enquire whether man varies, however slightly, in bodily structure and in mental faculties; and if so, whether the variations are transmitted to his offspring in accordance with the laws which prevail with tlie lower animals. Again, are the variations the result, as far as our ignorance permits us to judge, of the same general causes, and are they governed by the same general laws, as in the case of other organisms ; for instance, by correlation, the inherited effects of use and disuse, &c. ? Is man sulycct to similar mal- couformations, the result of arrested development, of reduplication of parts, &c., and does he display in any of his anomalies rever- sion to some former and ancient typo of structure ? It might also naturally be enquired whether man, like so many other animals, has given rise to varieties and sub-races, differing but slightly from each other, or to races differing so much that they must be classed as doubtful species? How are such races distributed over the world; and how, when crossed, do they react on each other in the first and succeeding generations ? And so with many other points. The enquirer would next come to the important point, whether man tends to increase at so rapid a rate, as to lead to occasional severe struggles for existence; and consequently to 6 The Descent of Man. Part I. beneficial variations, whether in body or mind, being preserved, and injurious ones eliminated. Do the races or species of men, whichever term may be applied, encroach on and replace one another, so that some finally become extinct ? We shall see that all these questions, as indeed is obvious in respect to most of them, must be answered in the affirmative, in the same manner as with the lower animals. But the several considerations just referred to may be conveniently deferred for a time : and we will first see how far the bodily structure of man shows traces, more or less plain, of his descent from some lower form. In succeeding chapters the mental powers of man, in comparison w^"th those of the lower animals, will be considered. The Bol'dy Structure of Man. — It is notorious that man is constructed on the same general type or model as other mam- mals. All the bones in his skeleton can be compared with corresponding bones in a monkey, bat, or seal. So it is with his muscles, nerves, blood-vessels and internal viscera. The brain, the most important of all the organs, follows the same law, as shewn by Huxley and other anatomists. Bischoff,^ who is a hostile witness, admits that every chief fissure and fold in the brain of man has its analogy in that of the orang ; but he adds that at no period of development do their brains perfectly agree ; nor could perfect agreement be expected, for otherwise their mental powers would have been the same. Vulpian ^ remarks : " Les differences reelles qui existent entre I'encephale de " t'homme et celui des singes superieurs, sont bien minimes. II " ne faut pas se faire d'illusions a cet egard. L'homme est bien " plus pres des singes anthropomorphes par les caracteres " anatomiques de son cerveau que ceux-ci ne le sont nou- " seulement des autres mammiferes, mais meme de certains " quadrumanes, des guenons et des macaques." But it would be superfluous here to give further details on the correspondence between man and the higher manmials in the structure of the brain and all other i^arts of the body. It may, however, be worth while to specify a few points, not directly or obviously connected with structure, by which this correspondence or relationship is well shewn. Man is liable to receive from the lower animals, and to com- 1 ' Grosshirnwiadungea des Men- in the Preface to this edition, scheu,' 1868, s. 96. The conchisions ^ t Le^_ g^^. i^ Phj-s.' 1866, p. 890, of this author, as well as those of as quoted by M. Dally, ' L'Ordre des Gratiolet and Aeby, concerning the Primates et leTranslbrmisme,' 1868, brain, will be discussed by Prof. p. 29. Huxley in the Appendix alluded to Chap. I. Hoinological Structures, 7 mnnicatc to them, certain diseases, as hydrophobia, varioUi, tho glanders, syphilis, cholera, herpes, etc. ; ^ and this fact proves tho close similarity* of their tissues and blood, both in minntc structure and composition, far more plainly than does their comparison under the best microscope, or by the aid of the best chemical analysis. Monkeys are liable to many of tho same non- contagious diseases as we are; thus Eengger,^ who carefully observed for a long time the Cthm Azarai in its native land, found it liable to catarrh, with the usual symptoms, and which, when often recurrent, led to consumption. These monkeys suffered also from apoph^xy, infiannnation of the bowels, and cataract in the eye. The younger ones when shedding their milk-teeth often died from fever. Medicines produced the same effect on them as on us. Many kinds of monkeys have a strong taste for tea, coffee, and spirituous liquors : they will also', as I have myself seen, smoke tobacco with pleasure." Brehm asserts, that the natives of north-eastern Africa catch the wild baboons by exposing vessels with strong beer, by which they are made drunk. He has seen some of these animals, which he kept in confinement, in this state ; and he gives a laughable account of their behaviour and strange grimaces. On the following morning they were very cross and dismal ; they held their aching heads with both hands, and wore a most pitiable expression : when beer or wine was offered them, they turned away with disgust, but relished the juice of lemons.^ An American monkey, an Ateles, after getting drunk on brandy, would never touch it again, and thus was wiser than many men. These trifling facts* prove how similar the nerves of taste must be in monkeys and man, and how similarly their whole nervous system is affected. Man is infested with internal parasites, sometimes causing ' Dr. W. Lauder Lindsay has tinct fluids by the same chemical treated this subject at some length reagent. in the ' Journal of Mental Science,' * ' Naturgescliichte der Siiuge- July 1871; and in the 'Edinburgh thiere von Paraguay,' 1830, s. 50. Veterinary lieview,' July 1858. ® The same tastes are common to * A Rev.ewer has criticised some animals much lower in the (' British Quarterly Review,' Oct. scale. Mr. A. Nicols informs me 1st, 1871, p. 472) what I have here that he kept in Queensland, in Aus- said with much severity and con- tralia, three individuals of the tempt; but as I do not use the term Fhaseolarctus cinereus ; and that, identity, I cannot see that I am without having been taught in any greatly in error. There apjiears to way, they acquired a strong taste me a strong analogy between the for rum, and for smoking tobacco, "same infection or contagion pro- ^ Brehm, 'Thicrleben,' B. i. 1864, ducing the same result, or one s. 75, 86. On the Ateles, s. 105. closely similar, in two distinct ani- For other analogous statements, see mals, and the testing of two dis- s. 25, 107. 8 The Descent of Man. Part I. fatcal effects ; and is plagued by external parasites, all of which belong to the same genera or families as those infesting other mammals, and in the case of scabies to the same species.^ Man is subject, like other mammals, birds, and even insects,^ to that mysterious law, which causes certain normal processes, such as gestation, as well as the maturation and duration of various diseases, to follow lunar periods. His wounds are repaired by the same process of healing; and the stumps left after the amputation of his limbs, especially during an early embryonic period, occasionally possess some power of regeneration, as in the lowest animals.'" The whole process of that most important function, the reproduction of the species, is strikingly the same in all mam- mals, from the first act of courtship by the male," to the birth and nurturing of the young. Monkeys are born in almost as helpless a condition as our own infants ; and in certain genera the young differ fully as much in appearance from the adults, as do our children from their full-grown parents.'^ It has been urged by some writers, as an important distinction, that with man the young arrive at maturity at a much later age than with any other animal : but if we look to the races of mankind which inhabit tropical countries the difference is not great, for the orang is believed not to be adult till the age of from ten to fifteen years.'^ Man differs from woman in size, bodily strength, hairiness, &c., as well as in mind, in the same manner as do the . ^ Dr. W. Lauder Lindsay, ' Edrn- " sagax, hoc mihi certissime pro- burgh Vet. Review,' July 1858, " bavit, et curatores ejusdem loci et p. 13. " alii e ministris confirmaverunt. ^ With respect to insects see Dr. " Sir Andrew Smith et Brehm no- Laycock, " On a General Law of Vital " tabant idem in Cynocephalo. II- Periodicity," ' British Association,' " lustrissimus Cuvier etiam narrat 1842. Dr. Macculloch, ' Silliman's *' multa de hac re, qua ut opinor, North American Journal of Science,' " nihil turpius potest indicari inter vol. xvii. p. 305, has seen a dog " omnia hominibus et Quadrumanis suffering from tertian ague. Here- " communia. Narrat enim Cyno- after I shall return to this subject. " cephalum quendam in furorem in- ^o I haA-e given the evidence on " cidere aspectu feminarum ali- this head in my ' Variation of Ani- " quarum, sed nequaquam accendi mals and Plants under Domestica- " tanto furore ab omnibus. Sem- tion,' Tol. ii. p. 15, and more could " per eligebat juniores, et dignos- be added. " cebat in turba, et advocabat voce •^ " Mares e diversis generibus " gestuque." " Quadrumanorum sine dubio di- '^ This remark is made with re- " gnoscunt feminas humanas a ma- spect to Cynocephalus and the an- " ribus. Primum, credo, odoratu, thropomorphous apes by Geoffrey " postea aspectu. Mr. Youatt, qui Saint-Hilaire and F. Cuvier, ' Hist, *' diu in Hortis Zoologicis (Besti- Nat. des Mammiferes,' tom. 1. 1824. " ariis) medicus animalium erat, ^^ Huxley, ' Man's Place in Na- " vir in rebus observandis cautus et ture,' 1863, p. 34. (^.iiAP. 1. Homological Structures. 9 two sexes of many mammals. So that the correspondence in general structure, in the minute structure of the tissues, in chemical composition and in constitution, between man and tlie liigher animals, especially the anthropomorphous apes, is ex- tremely close. Emhnjonlc Dcv^Ioj-mcnt. — Man is developed from an ovule, about the 125th of an inch in diameter, which diifcrs in no respect from the ovules of other animals. The embryo itself at a very early period can hardly be distinguished from that of other members of the vertebrate kingdom. At this period the arteries run in arch-like branches, as if to carry the blood to branchite which are not present in the higher vertebrata, though the slits on the sides of the neck still remain (/, g, fig. 1), marking their former position. At a somewhat later period, when the extremities are developed, " the feet of lizards and " mammals," as the illustrious Von Baer remarks, " the wings " and feet of birds, no less than the hands and feet of man, all " arise from the same fundamental form." It is, says Prof. Huxley,^'* " quite in the later stages of development that the young human being presents marked differences from the young " ape, while the latter departs as much from the dog in its " developments, as the man does. Startling as this last assertion " may appear to be, it is demonstrably true." As some of my readers may never have seen a drawing of an embryo, I have given one of man and another of a dog, at about the same early stage of development, carefully copied from two works of undoubted accuracy.'^ After the foregoing statements made by such high autho- rities, it would be superfluous on my part to give a number of borrowed details, shewing that the embryo of man closely resembles that of other mammals. It may, however, be added, that the human embryo likewise resembles certain low forms when adult in various points of structure. For instance, the heart at first exists as a simple pulsating vessel; the excreta are voided through a cloacal passage ; and the os coccyx projects •* ' Man's Place in Nature,' 1863, magnified, the embryo being twenty- p, 67. five days old. The internal viscera '^ The human embryo (upper havebeenomitted, and theuterineap- fig.) is from Ecker, ' Icones Phys.,' pendages in both drawings removed. 1851-1859, tab. xxx. fig. 2. This I was directed to these figures by embryo was ten lines in length, so Prof. Huxley, from whose woj-k, that the drawing is much magnified. ' Man's Place in Nature,' the idea of The embryo of the dog is from givmg them was taken. Hiickcl has Jiischoff, ' Entwicklungsgeschichte also given analogous drawings in his des Humle-Eies,' 1845, tab. xi. fig. ' Schoufuugsgescliichte.' 42 B This drawing is five time? 2 10 The Descent of Man. Part I. Fig. 1. Upper figure human embryo, from 'Ecker. from BischofF. Lower figure that of a dog. a. Fore-brain, cerebral hemispheres, &c. 6. Mid-brain, corpora quadrigeniina. c. Hind-brain, cerebellum, medulla ob- longata. d. Eye. e. Ear. f. First visceral arch. <7. Second visceral arch. H. Vertebral columns and muscles process of development. i Anterior K. Posterior L. Tail or os coccyx. extremities. Chap. I. Riidivioits. 1 1 like a true tail, "extending considerably beyond the rudi- " mentary legs.""^ In the embryos of all air-breathing vertebrates, certain glands, called the corpora Wolffiana, correspond with, and act like the kidneys of mature fishes.''^ Even at a later embryonic period, some striking resemblances between man and the lower animals may be observed. Bischoflf says that the convolutions of the brain in a human foetus at the end of the seventh month reach about the same stage of develoj^ment as in a baboon when adult.^** The great toe, as Prof. Owen rcmarks,^^ " which forms the fulcrum when standing or w\alking, is " perhaps the * most characteristic peculiarity in the human structure ;" but in an embryo, about an inch in length. Prof. Wyman '^"^ found " that the great toe was shorter than the others ; " and, instead of being parallel to them, projected at an angle " from the side of the foot, thus corresponding with the per- *' manent condition of this part in the quadrumana." I will conclude with a quotation from Huxley ,^^ who after asking, does man originate in a different way from a dog, bird, frog or fish? says, "the reply is not doubtful for a moment; without " question, the mode of origin, and the early stages of the " development of man, are identical with those of the animals " immediately below him in the scale : without a doubt in " these respects, he is far nearer to apes than the apes are to " the dog." lludimenU. — This subject, though not intrinsically more important than the two last, will for several reasons be treated here more fully.-^ Kot one of the higher animals can be named which does not bear some part in a rudimentary condition ; and man forms no exception to the rule. Eudimentary organs must be distinguished from those that are nascent ; though in some cases the distinction is not easy. The former are either abso- lutely useless, such as the mammae of male quadrupeds, or the incisor teeth of ruminants which never cut through the gums ; or they are of such slight service to their present possessors, that w^e can hardly suppose that they were developed under the '* Prof. Wyman in * Proc. of ^^ I had written a rough copy of American Acad, of Sciences,' rol. iv. this chapter before reading a valu- 1860, p. .17, able paper, " Caratteri rudimentali *' Owen, ' Anatomy of Verte- in ordine all' origine del iiomo " brates,' vol. i. p. 533. (' Annuario della Soc. d. Nat.,' Mo- '* 'Die Grosshirnwinduugen des dena, 1867, p. 81), by G. Canestrini, Menschen,' 1868, s. 95. to which paper I am considerably '^ 'Anatomy of Vertebrates,' vol. indebted. Hiickel has given admir- ji. p. 553. able discussions on this whole sub- '^° ' Proc. Soc. Nat. Hist.' Boston, ject, under the title of Dysteleology, 1863, vol. ix. p. 185. in his ' Generelle Morphologic' and '* ' Man's Place in Nature,' p. 65. ' Schopfungsgeschichta.' 1 2 The Descent of Man. Part I. conditions wliicli now exist. Organs in this latter state are not strictly rudimentary, but they are tending in this direction. Nascent organs, on the other hand, though not fully developed, are of high service to their possessors, and are capable of further development. Rudimentary organs are eminently variable ; and this is partly intelligible, as they are useless, or nearly useless, and consequently are no longer subjected to natural selection. They often become wholly suppressed. When this occurs, they are nevertheless liable to occasional reappearance through reversion— a circumstance well worthy of attention. The chief agents in causing organs to become rudimentary seem to have been disuse at that period of life when the organ is chiefly used (and this is generally during maturity), and also inheritance at a corresponding period of life. The term " disuse " does not relate merely to the lessened action of muscles, but includes a diminished flow of blood to a part or organ, from being subjected to fewer alternations of pressure, or from becoming in any way less habitually active. Eudiments, however, maj occur in one sex of those parts which are normally present in the other sex; and such rudiments, as we shall hereafter see, have often originated in a way distinct from those here referred to. In some cases, organs have been reduced by means of natural selection, from having become injurious to the species under changed habits of life. The process of reduction is probably often aided through the two principles of compensa- tion and economy of growth ; but the later stages of reduction, after disuse has done all that can fairly be attributed to it, and when the saving to be effected by the economy of growth would be very small/^ are difl&cult to understand. The final and complete suppression of a part, already useless and much reduced in size, in which case neither compensation nor economy can come into play, is perhaps intelligible by the aid of the hypothesis of pangenesis. But as the wliole subject of rudimentary organs has been discussed and illustrated in my former works,^^ I need here say no more on this head. Eudiments of various muscles have been observed in many parts of the human body ;^^ and not a few muscles, which are ^^ Some good criticisms on this Zoolog. 1852, torn, xviii. p. 13) de- subject have been given by Messrs. scribes and figures rudiments of Murie and Mivart, in 'Transact. what he calls the " muscle pe'dieux Zoolog. Soc' 1869, vol. vii. p. 92. de la main," which he says is some- 2* ' Variation of Animals and times " ipfiniment petit." Another Plrnts under Domestication,' vol. ii. muscle, called " le tibial posterieur," pp. 317 and 397. See also ' Oj-igin is generally quite absent in the of Species,' 5th edit. p. 535, hand, but appears from time to time 2* For instance M. Richard (' An- in a more or less rudimentary con- uales des Sciem'.es Nat.' 3i-d sex'ies, dltion. Chap. I. Riidii}ie]its. 13 regularly present in some of the lower animals can occasionally be detected in man in a greatly reduced condition. Every one must have noticed the power which many animals, especially horses, possess of moving or twitchiDg their skin; and this is effected by the panniculns carnosus. Remnants of this muscle in an efficient state are found in various parts of our bodies ; for instance, the muscle on the forehead, by which the eyebrows are raised. The /^A/Zysywa myoides, which is well developed on the neck, belongs to this system. Prof. Turner, of Edinburgh, has occasionally detected, as he informs me, muscular lasciculi in five different situations, namely in the axillae, near the scapulae, &c., all of which must be referred to the system of the jianni- culus. He has also shewn ^'^ that the muscnlus stemalis or stemalis hrutorum, which is not an extension of the rectus abdominal is, but is closely allied to the pannicidas, occurred in the proportion of about three per cent, in upwards of 600 bodies : he adds, that this muscle affords "an excellent illustration of the statement " that occasional and rudimentary structures are especially " liable to variation in arrangement." Some few persons have the power of contracting the super- ficial muscles on their scalps ; and these muscles are in a variable and partially rudimentary condition. M. A. de Candolle has communicated to me a curious instance of the long-continued persistence or inheritance of this power, as well as of its unusual development. He knows a family, in which one member, the present head of the family, could, when a youth, pitch several heavy books from his head by the movement of the scalp alone ; and he won wagers by performing this feat. His father, uncle, grandfather, and his three children possess the same power to the same unusual degree. This family became divided eight generations ago into two branches; so that the head of the above-mentioned branch is cousin in the seventh degree to the head of the other branch. This distant cousin resides in another part of France ; and on being asked whether he possessed the same faculty, immediately exhibited his power. This case offers a good illustration how persistent may be the transmission of an absolutely useless faculty, probably derived from our remote semi- human progenitors; since many monkeys have, and frequently use the power, of largely moving their scalps up and down." The extrinsic muscles which serve to move the external ear, and the intrinsic muscles which move the different parts, are in a rudimentary condition in man, and they all belong to the system '« Prof. W. Turner, ' Proc. Royal Emotions in Man and Animals,' Soc. Edinburgh,' 1866-67, p. 65. 1872, p. 144. -^ See my ' Expression of the 14 The Descent of Man. Part 1 of the panniculus ; they are also variable in development, or at least in function. I have seen one man who could draw the whole ear forwards ; other men can draw it upwards ; another who could draw it backwards f^ and from what one of these persons told me, it is probable that most of us, by often touching our ears, and thus directing our attention towards them, could recover some power of movement by repeated trials. The power of erecting and directing the shell of the ears to the various points of the compass, is no doubt of the highest service to many animals, as they thus perceive the direction of danger; but I have never heard, on sufficient evidence, of a man who possessed this power, the one which might be of use to him. The whole external shell may be considered a rudiment, together with the various folds and prominences (helix and anti-helix, tragus and anti-tragus, &c.) which in the lower animals strengthen and support the ear when erect, without adding much to its weight. Some authors, however, suppose that the cartilage of the shell serves to transmit vibrations to the acoustic nerve; but Mr. Toynbee,^^ after collecting all the known evidence on this head, concludes that the external shell is of no distinct use. The ears of the chimpanzee and orang are curiously like those of man, and the proper muscles are likewise but very slightly developed. "° I am also assured by the keepers in the Zoological Gardens that these animals never move or erect their ears ; so that they are in an equally rudimentary condition with those of man, as far as function is concerned. Why these animals, as well as the progenitors of man, should have lost the power of erecting their ears, we cannot say. It may be, though I am not satisfied with this view, that owing to their arboreal habits and great strength they were but little exposed to danger, and so during a lengthened period moved their ears but little, and thus gradually lost the power of moving them. This would be a parallel case with that of those large and heavy birds, which, from inhabiting oceanic islands, have not been exposed to the attacks of beasts of prey, and have consequently lost the power of using their wings for flight. The inability to move the ears in man and several apes is, however, partly com- pensated by the freedom with which they can move the head in 2* Canestrini quotes Hyrtl. (' An- lately been experimenting on the nuario della Soc. dei Naturalist!, ' function of the shell of the ear, Modena, 1867, p. 97) to the same and has come to nearly the same effect. conclusion as that given here. "^^ ' The Diseases of the Ear,' by ^o p^-of. A. Macalister, ' Annals J. Toynbee, F.R.S., 1860, p. 12. and Mag. of Nat. History,' vol, vii.. A distinguished physiologist. Prof. 1871, p. 342. Preyer, informs me that he had Chap. I. Rudiments. 15 a horizontal plane, so as to catch sounds from all directions. It lias been asserted that the ear of man alone possesses a lobule ; but "a rudiment of it is found in the gorilla ;"^^ and, as I hear from Prof. Prefer, it is not rarely absent in the negro. The celebrated sculptor, Mr. Woolner, informs me of one little peculiarity in the external ear, which he has often observed both in men and women, and of which he perceived the lull signi- ficance. His attention was first called to the subject whilst at work on his figure of Puck, to which he had given pointed ears. He was thus led to examine the ears of various monkeys, and sub- sequently more carefully those of man. The peculiarity consists in a little blunt point, projecting from the inwardly folded margin, or helix. WHien present, it is developed at birth, and, iiccording to Prof. Ludwig Meyer, more frequently in man than in woman. Mr. Woolner made an exact model of one such case, and sent me the accompanying drawing. (Fig. 2.) These points not only project inwards towards the centre of the ear, but often a little outwards from its plane, so as to be visible when the head is viewed from directly in front or behind. They are variable in size, and somewhat in position, standing either a little higher or lower; and they sometimes occur on one ear and not on the other. They are not confined to mankind, for I ob- served a case in one of the spider- monkeys (Ateles beehfhufh) in our Zoological Gardens; and Dr. E. Pay Lankester informs me of another case in a chimpanzee in the gardens at Hamburg. The helix obviously con- sists of the extreme margin of the ear folded inwards; and this folding appears to be in some manner connected with the whole external ear being permanently pressed backwards. In many monkeys, which do not stand high in the order, as baboons and some species of macacus,^^ the upper portion of the ear is slightly pointed, and the margin is not at all folded inwards ; but if the margin were to be thus folded, a slight point would necessarily project inwards towards the centre, and probably a little outwards from the plane of the ear ; and this I believe to ^* Mr. St. George Mivart, ' Ele- Lemuroidea, in Messrs. Murie and mentary Anatomy,' 1873, p. 396. ]\Iivart's excellent paper in 'Tran« 32 See also some remarks, and sact. Zoolog. Soc' vol. vii. 1869, pp. the drawings of the ears of the 6 and 90. Fig 2. Unman Ear. morielled and drawn by Mr. Woolner. a. The projecting point. 1 6 TJie Descent of Man. Part I. be their origin in many cases. On the other hand, Prof. L. Meyer, in an able paper recently pubhshed,^ maintains that the whole case is one of mere variability ; and that the projections are not real ones, but are due to the internal cartilage on each side of the points not having been fully developed. I am quite ready to admit that this is the correct explanation in many instances, as in those figured by Prof. Meyer, in which there are several minute points, or the whole margin is sinuous. I have myself seen, through the kindness of Dr. L. Down, the ear of a micro- cephalous idiot, on which there is a projection on the outside of the helix, and not on the inward folded edge, so that this point can have no relation to a former apex of the ear. Never- theless in some cases, my original view, that the points are vestiges of the tips of formerly erect and pointed ears, still seems to me probable. I think so from the frequency of their occurrence, and from the general correspondence in position with that of the tip of a pointed ear. In one case, of which a photograph has been sent me, the projection is so large, that supposing, in accordance with Prof. Meyer's view, the ear to be made perfect by the equal development of the cartilage throughout the whole extent of the margin, it would have covered fully one-third of the whole ear. Two cases have been communicated to me, one in North America, and the other in England, in wliich the upper margin is not at all folded inwards, but is pointed, so that it closely resembles the pointed ear of an ordinary quadruped in outline. In one of these cases, which was that of a young child, the father compared the ear with the drawing which I have given^^ of the ear of a monkey, the Cynopithecus rdger, and says that their outlines are closely similar. If, in these two cases, the margin had been folded inwards in the normal manner, an inward projection must have been formed. I may add that in two other cases the outline still remains somewhat pointed, although the margin of the upper part of the ear is normally folded inwards — in one of them, however, very narrowly. The following woodcut (No. 3) is an accurate copy of a photograph of the foetus of an orang (kindly sent me by Dr. Nitsche), in which it may be seen how different the pointed outline of the ear is at this period from its adult condition, when it bears a close general resemblance to that of man. It is evident that the folding over of the tip of such an ear, unless it changed greatly during its further development, would give rise to a point projecting inwards. On the whole, it still seems to '^ Ueber das Darwin'sche Spitzohr, ^* 'The Expression of the Emo- Archiv fiir Path. Anat. und Phys. tions,' p. 136. 1871, p. 485. Chap. I. Riidiinents. 17 me probable that the points in question are in some cases, both in man and apes, vestiges of a former condition. Fig 3. Foetus of an OranR. Fxact copy of a photograph, shewing the form of the ear at this early age. The nictitating membrane, or third eyelid, with its accessory mnscles and other structures, is especially well developed in birds, and is of much functional importance to them, as it can be rapidly drawn across the whole eye-ball. It is found in some reptiles and amphibians, and in certain fishes, as in sharks. It is fairly well developed in the two lower divisions of the mam- malian series, namely, in the monotreraata and marsupials, and in some few of the higher mammals, as in the walrus. But in man, the quadruraana, and most other mammals, it exists, as is admitted by all anatomists, as a mere rudiment, called the semilunar fold.^^ The sense of smell is of the highest importance to the greater number of mammals— to some, as the ruminants, in warning them of danger; to others, as the carnivora, in finding their prey; to others, again, as the wild boar, for both purposes combined. But the sense of smell is of extremely slight service, if any, even to the dark coloured races of men, in whom it is " Miillev's 'Elements of Physi- ology,* Eng. translat., 1842. vol. ii. p. 1117. Owen, * Anatomy of Verte- brates,' vol. iii. p. 260; ibid, on the Walrus, * Proo. Zoolog. Soc' November 8th, 1854. See also R. Knox, 'Great Artists and Anato- mists,' p. 106. This rudiment ap- parently is somewhat larger in Negroes and Australians than in Europeans, see Carl Vogt, ' Lectures on Man,' Eng. translat. p. 129. 1 8 The Descent of Man. Part I. much more highly deyeloped than in the white and civilised races."^ Nevertheless it does not warn them of danger, nor guide them to their food ; nor does it prevent the Esquimaux from sleeping in the most fetid atmosphere, nor many savages from eating half-putrid meat. In Europeans the power differs greatly in different individuals, as I am assured by an eminent naturalist who possesses this sense highly developed, and who has at- tended to the subject. Those who believe in the principle of gradual evolution, will not readily admit that the sense of smell in its present state was originally acquired by man, as he now exists. He inherits the power in an enfeebled and so far rudimentary condition, from some early progenitor, to whom it was highly serviceable, and by whom it was con- tinually used. In those animals which have this sense lughly developed, such as dogs and horses, the recollection of persons and of places is strongly associated with their odour ; and we can thus perhaps understand how it is, as Dr. Maudsley has truly remarked,^^ that the sense of smell in man " is singularly effective " in recalHng vividly the ideas and images of forgotten scenes " and places." Man differs conspicuously from all the other Primates in being almost naked. But a few short straggling hairs are found over the greater part of the body in the'mau, and fine down on that of the woman. The different races differ much in hairiness ; and in the individuals of the same race the hairs are highly variable, not only in abundance, but likewise in position : thus in some Europeans the shoulders are quite naked, whilst in others they bear thick tufts of hair.^^ There can be little doubt that the hairs thus scattered over the body are the rudiments of the uniform hairy coat of the lower animals. This view is rendered all the more probable, as it is known that fine, short, and pale- coloured hairs on the limbs and other parts of the body, occasion- ^^ The account given by Humboldt olfactory region, as well as of the of the power of smell possessed by skin of the body. I have, therefore, the natives of South America is well spoken in the text of the dark- known, and has been confirmed by coloured races having a finer sense others. M. Hoiizeau (' Etudes sur of smell than the white races. See les Faculte's Mentales,' &c., torn. i. his paper, ' Medico-Chirurgical Tran- 1872, p. 91) asserts that he re- sactions,' London, vol. liii., 1870, peatedly made experiments, and p. 276. proved that Negroes and Indians ^^ ' The Physiology and Pathology could recognise persons in the dark of Mind,' 2nd edit. 1868, p. 134-. by their odour. Dr. W. Ogle has ^s Eschricht, Ueber die Kichtung made some curious observations on der Haare am menschlichen Korper, the connection between the power 'Miiller's Archivfur Anat.und Phys.' of smell and the colouring matter 1837, s. 47. I shall often have to of the mucous membrane of the refer to this very curious paper. Chap. I. Rudiments. 19 ally become developed into " thickset, long, and rather coarse " dark hairs," when abnormally nourished near old-standing inflamed surfaccs.^^ I am informed by Sir James Paget that often several members of a family have a few hairs in their eyebrows much longer than the others; so that even this slight peculiarity seems to be inherited. These hairs, too, seem to have their repiesentatives ; for in the chimpanzee, and in certain sjDecies of Macacus, there are scattered hairs of considerable length rising from the naked skin above the eyes, and corresponding to our eyebrows ; similar long hairs project from the hairy covering of the superciliary ridges in some baboons. The fine wool-like hair, or so-called lanugo, with which the human foetus during the sixth month is thickly covered, ofifers a more curious case. It is first developed, daring the fifth month, on the eyebrows and face, and especially round the mouth, where it is much longer than that on the head, A moustache of this kind was observed by Eschriclit^° on a female foetus ; but this is not so surprising a circumstance as it may at first appear, for the two sexes generally resemble each other in all external characters during an early period of growth. The direction and arrangement of the hairs on all parts of the foetal body are the same as in the adult, but are subject to much variability. The whole surface, including even the forehead and ears, is thus tliickly clothed ; but it is a significant fact that the palms of the hands and the soles of the feet are quite naked, like the inferior surfaces of all four extremities in most of the lower animals. As this can hardly be an accidental coincidence, the woolly cover- ing of the foetus probably repres(;nts the first permanent coat of hair in those mammals which are born hairy. Three or four cases have been recorded of persons born with their whole bodies and faces thickly covered with fine long hairs ; and this strange condition is strongly inherited, and is correlated with an abnor- mal condition of the teeth.'*^ Prof. Alex. Brandt informs me that he has compared the hair from the face of a man thus charac- terised, aged thirty-five, with the lanugo of a foetus, and finds it quite similar in texture ; therefore, as he remarks, the case may be attributed to an arrest of development in the hair, together with its continued growth. Many delicate children, as I have ^' Paget, 'Lectures on Sui'gical has recently sent me an additional Pathology,' 1853, vol. i. p. 71. case of a father and son, born in ■*° Eschrichi, ibid. s. 40, 47. Piussia, with these peculi;irities. I ** See my ' Variation of Animals have received drawings of both from and Plants under Domestication,' Paris. vol. ii. p. 327. Prof. Alex. Brandt 20 The Descent of Man. Part I. been assured by a surgeon to a hospital for children, have their backs covered by rather long silky hairs ; and such cases pro- bably come under the same head. It appears as if the posterior molar or wisdom-teeth were tending to become rudimentary in the more civilised races of man. These teeth are rather smaller than the other molars, as is likewise the case with the corresponding teeth in the chim- panzee and orang ; and they have only two separate fangs. They do not cut through the gums till about the seventeenth year, and I have been assured that they are much more liable to decay, and are earlier lost than the other teeth ; but this is denied by some eminent dentists. They are also much more liable to vary, both in structure and in the period of their development, than the other teeth.'*'^ In the Melanian races, on the other hand, the wisdom-teeth are usually furnished with three separate fangs, and are generally sound ; they also differ from the other molars in size, less than in the Caucasian races.*^ Prof. Schaaffhausen accounts for this difference between the races by " the posterior dental portion of the jaw being always " shortened" in those that are civilised,^* and this shortening may, I presume, be attributed to civilised men habitually feeding on soft, cooked food, and thus using their jaws less. I am informed by Mr. Brace that it is becoming quite a common practice in the United States to remove some of the molar teeth of children, as the jaw does not grow large enough for the perfect development of the normal number.^^ With respect to the alimentary canal, I have met with an account of only a single rudiment, namely the vermiform append- age of the caecum. The caecum is a branch or diverticulum of the intestine, ending in a cul-de-sac, and is extremely long in many of the lower vegetable-feeding mammals. In the marsupial koala it is actually more than thrice as long as the whole body.^^ It is sometimes produced into a long gradually-tapering point, and is sometimes constricted in parts. It appears as if, in con- sequence of changed diet or habits, the caecum had become much 42 Dr. Webb, 'Teeth in Man and from Florence, that he has lately the Anthropoid Apes,' as quoted by been studying the last molar teeth Di*. C. Carter Blake in ' Anthropo- in the different races of man, and logical Review,' July 1867, p. 299. has come to the same conclusion as ■*3 Owen, ' Anatomy of Verte- that given in my text, viz., that in brates,' vol. iii. pp. 320, 321, and the higher or civilised races they 325. are on the road towards atrophy or ** 'On the Primitive Form of the elimination. Skull,' Eng. translat. in 'Anthropo- ^^ Owen, 'Anatomy of Verte- logical Review,' Oct. 1868, p. 426. brates,' vol. iii. pp. 416, 434, 441. ^= Prof. Montegazza writes to me Chap. I. Rudiments. 21 shortened in various animals, the vermiform appendage being left as a rudiment of the shortened part. That this appendage is a rudiment, we may infer from its small size, and from the evidence which Prof. Canestrini*^ has collected of its variability in man. It is occasionally quite absent, or again is largely developed. The passage is sometimes completely closed for half or two-thirds of its length, with the terminal part consisting of a flattened solid expansion. In the orang this appendage is long and convoluted: in man it arises from the end of the short caecum, and is commonly from four to five inches in length, being only about the third of an inch in diameter. Kot only is it useless, but it is sometimes the cause of death, of which fact I have lately heard two instances : this is due to small hard bodies, such as seeds, entering the passage, and causing inflam- mation."*^ In some of the lower Quadrumana, in the Lemurida3 and Carnivora, as well as in many marsupials, there is a passage near the lower end of the humerus, called the supra-condyloid fora- men, through which the great nerve of the fore limb and often the great artery pass. Now in the humerus of man, there is generally a trace of this passage, which is sometimes fairly well developed, being formed by a depending hook -like process of bone, completed by a band of ligament. Dr. Struthers,''^ who has closely attended to the subject, has now shewn that this peculiarity is sometimes inherited, as it has occurred in a father, and in no less than four out of his seven children. When pre- sent, the great nerve invariably passes through it; and this clearly indicates that it is the homologue and rudiment of the supra-condyloid foramen of the lower animals. Prof. Turner estimates, as he informs me, that it occurs in about one per cent, of recent skeletons. But if the occasional development of this structure in man is, as seems probable, due to reversion, it is a return to a very ancient state of things, because in the higher Quadrumana it is absent. There is another foramen or perforation in the humerus, <^ 'Annuario della Soc, d. Nat' Feb. 15, 1873, and another im- Modena, 1867, p. 94. portant paper, ibid., Jan. 24, 1863, ■"8 M. C. Martins (*' De I'Unite p. 83. Dr. Knox, as I am informed, Orgauique," in ' Revue des Deux was the first anatomist who drew Moudes,' June 15, 1862, p. 16), and attention to this peculiar structure Hackel (' Generelle Morphologic,' in man ; see his ' Great Artists and B. ii. s. 278), have both remarked Anatomists,' p. 63. See also an im- on the singular fact of this rudi- portant memoir on this process by ment sometimes causing death. Dr. Gruber, in the ' Bulletin de ** With respect to inheritance, I'Acad. Imp. de St. Pe'tersbourg,' see Dr. Struthers in the ' Lancet,' tom. xii. 1867, p. 448. 22 The Descent of Man. Part I. occasionally present in man, which may be called the inter- condyloid. This occurs, but not constantly, in various anthro- poid and other apes,^" and likewise in many of the lower animals. It is remarkable that this perforation seems to have been present in man much more frequently during ancient times than recently. Mr. Busk^^ has collected the following evidence on this head : Prof. Broca " noticed the perforation in four and a "half per cent, of the arm-bones collected in the ' Cimetiere du " Sud,' at Paris ; and in the Grotto of Orrony, the contents of " which are referred to the Bronze period, as many as eight " humeri out of thirty-two were perforated ; but this extraordi- " nary proportion, he thinks, might be due to the cavern having " been a sort of ' family vault.' Again, M. Dupont found thirty " per cent, of perforated bones in the caves of the Valley of the '' Lesse, belonging to the Eeindeer period ; whilst M. Leguay, in " a sort of dolmen at Argenteuil, observed twenty -five per cent, "to be perforated; and M. Pruner-Bey found twenty-six per " cent, in the same condition in bones from Yaureal. Nor should ''it be left unnoticed that M. Pruner-Bey states that this con- '* dition is common in G-uanche skeletons." It is an interesting fact that ancient races, in this and several other cases, more frequently present structures which resemble those of the lower animals than do the modern. One chief cause seems to be that the ancient races stand somewhat nearer in the long line of descent to their remote animal-like progenitors. In man, the os coccyx, together with certain other vertebrae hereafter to be described, though functionless as a tail, plainly represent this part in other vertebrate animals. At an early embryonic period it is free, and projects beyond the lower extremities ; as may be seen in the drawing (Fig. 1.) of a human embryo. Even after birth it has been known, in certain rare and anomalous cases,^^ to form a small external rudiment of a tail. The os coccyx is short, usually including only four vertebrEe, all anchylosed together: and these are in a rudi- *" Mr. St. George Mivart, ' Trans- ^2 Quatrefages has lately collected act. Phil. Soc' 1867, p. 310. the evidence on this subject. ' Revue " "On the Caves of Gibraltar," des Cours Scientifiques,' 1867-1868, 'Transact. Internat. Congress of p. 625. In 1840 Fleischmann ex- Prehist. Arch.' Third Session, 1869, hibited a human foetus bearing a p. 159. Prof. Wyman has lately free tail, which, as is not always the shewn (Fourth Annual Report, Pea- case, included vertebral bodies ; and body Museum, 1871, p. 20), that this this tail was critically examined by perforation is present in thirty-one the many anatomists present at the per cent, of some human remains meeting of naturalists at Erlangen from ancient mounds in the Western (see Marshall in Niederltindischen United States, and in Florida. It Archivfiir Zoologie, Decemberl871). frequently occurs in the negro. Chap. I. Rudimejits. 23 mentary condition, for they consist, with the exception of tlie basal one, of the centrum alone.^^ They are furnished with some small muscles ; one of which, as I am informed by Prof. Turner, has been exj^ressly described by Theile as a rudimentary repetition of the extensor of the tail, a muscle which is so largely developed in many mammals. The spinal cord in man extends only as far downwards as the last dorsal or first lumbar vertebra; but a thread-like struc- ture {i\\Q. filum ttrminah-^ runs down the axis of the sacral part of the spinal canal, and even along the back of the coccygeal bones. The upper part of this filament, as Prof. Turner informs me, is undoubtedly homologous with the spinal cord ; but the lower part apparently consists merely of the pia mater, or vascular investing membrane. Even in this case the os coccyx may be said to possess a veslige of so important a structure as the spinal cord, though no longer enclosed within a bony canal. The following fact, for which I am also in- debted to Prof. Turner, shews how closely the os coccyx corre- sponds with the true tail in the lower animals : Luschka has recently discovered at the extremity of the coccygeal bones a very peculiar convoluted body, which is continuous with the middle sacral artery ; and this discovery led Krause and Meyer to examine the tail of a monkey (Macacus), and of a cat, in both of which they found a similarly convoluted body, though not at the extremity. The reproductive system offers various rudimentary struc- tures; but these differ in one important respect from the foregoing cases. Here we are not concerned with the vestige of a part which does not belong to the species in an efficient state, but with a part efficient in the one sex, and represented in the other by a mere rudiment. Nevertheless, the occurrence of such rudiments is as difficult to explain, on the belief of the separate creation of each species, as in the foregoing cases. Hereafter I shall have to recur to these rudiments, and shall shew that their presence generally depends merely on inheri- tance, that is, on parts acquired by one sex having been partially transmitted to the other. I will in this place only give somQ instances of such rudiments. It is well known that in the males of all mammals, including man,, rudimentary mammae exist. These in several instances have become well developed, and have yielded a copious supply of milk. Their essential identity in the two sexes is likewise shewn by their occasional sympathetic enlargement in both during an attack of the " Owen, 'On the Nature of Limbs,' 1849, p. 114. 24 The Desceiit of Mmi. Paet I. measles. The vesicula prostatlca, which has been observed in many male mammals, is now universally acknowledged to bo the homologne of the female uterus, together with the con- nected passage. It is impossible to read Leuckart's able de'scription of this organ, and his reasoning, without admitting the justness of his conclusion. This is especially clear in the case of those mammals in which the true female uterus bifurcates, for in the males of these the vesicula likewise bifurcates.^* Some other rudimentary structui-es belonging to the reproductive system might have been here adduced. ^^ The bearing of the three great classes of facts now given is unmistakeable. But it would be superfluous fully to recapitulate the line of argument given in detail in my ' Origin of Species.' The homological construction of the whole frame in the members of the same class is intelligible, if we admit their descent from a common progenitor, together with their subsequent adaptation to diversified conditions. On any other view, the similarity of pattern between the hand of a man or monkey, the foot of a horse, the flipper of a seal, the wing of a bat, &c., is utterly inexplicable,^^ It is no scientific explanation to assert that they have all been formed on the same ideal plan. With respect to development, we can clearly understand, cm the principle of '* Leuckart, in Todd's 'Cyclop. words) a mere metaphysical prin- vf Anat.' 1849-52, vol. iv. p. 1415. ciple, namely, the preservation "in In man this organ is only from " its integrity of the mammalian three to six lines in length, but, " nature of the animal." In only a like so many other rudimentary few cases does he discuss rudiments, parts, it is variable in development and then only those parts which are as well a^ in other characters. partially rudimentary, such as the 5^ See, on this subject, Owen, little hoofs of the pig and ox, which 'Anatomy of Vertebrates,' vol. iii. do not touch the ground; these he pp. 675, 676, 706. shews clearly to be of service to the ^s Prof. Bianconi, in a recently animal. It is unfortunate that he published work, illustrated by ad- did not consider such cases as the mirable engravings (' La The'orie minute teeth, which never cut Darwiuienne et la creation dite in- through the jaw in the ox, or the de'pendante,' 1874), endeavours to mammae of male quadrupeds, or the show that homological structures, in wings of certain beetles, existing the above and other cases, can be under the soldered wing-covers, or fully explained on mechanical prin- the A'estiges of the pistil and stamens ciples, in accordance with their uses, in various flowers, and man}f other No one has shewn so well, how ad- such cases. Although 1 greatly mirably such structures are adapted admire Prof. Bianconi's work, yet for their final purpose; and this the belief now held by most natural- adaptation can, as I believe, be ists seems to me left unshaken, explained through natural selection. that homological structures are in- In considering the wing of a'bat, he explicable on the principle of mere brings forward (p. 218) what appears adaptation. to me (to use Auguste Comte's Chap. I. Rjidimetits. 2$ ■variations supervening at a rather late embryonic period, and being inherited at a corresponding period, how it is that the embryos of wonderfully different forms should still retain, more or less perfectly, the structure of their common progenitor. No other explanation has ever been given of the marvellous fact that the embryos of a man, dog, seal, bat, reptile, &c., can at first hardly be distinguished from each other. In order to understand the existence of rudimentary organs, we have only to suppose that a former progenitor possessed the parts in question in a perfect state, and that under changed habits of life thoy became greatly reduced, either from simple disuse, or through the natural selection of those individuals which were least encumbered with a superfluous part, aided by the other means previously in- dicated. Thus we can understand how it has come to pass that man and all other vertebrate animals have been constructed on the same general model, why they pass through the same early stages of development, and why they retain certain rudiments in common. Consequently we ought frankly to admit their community of descent; to take any other view, is to admit that our own structure, and that of all the animals around us, is a mere snare laid to entrap our judgment. This conclusion is greatly strengthened, if we look to the members of the whole animal series, and consider the evidence derived from their affinities or classification, their geographical distribution and geolo- gical succession. It is only our natural prejudice, and that arrogance which made our forefathers declare that they were descended from demi-gods, which leads us to demur to this conclusion. But the time will before long come, when it will be thought wonderful that naturalists, who were well acquainted with the comparative structure and development of man, and other mammals, should have believed that each was the work of a separate act of creation. 26 The Descent of Man. Part L CEAPTEE n. On the Manner of Development of Man from some Lower Form. Variability of body and mind in man — Inheritance — Causes of variability — Laws of variation the same in man as in the lower animals — Direct action of the conditions of life — Effects of the increased use and disuse of parts — Arrested development — Reversion — Correlated variation — Rate of increase — Checks to increase — Natural selection — Man the most dominant animal in the world — Importance of his corporeal structure — The causes which have led to his becoming erect — Consequent changes of structure — Decrease in size of the canine teeth — Increased size and altered shape of the skull — Nakedness — Absence of a tail — Defenceless condition of man. It is manifest that man is now subject to much yariability. No two individuals of the same race are quite alike. We may compare millions of faces, and each will be distinct. There is an equally great amount of diversity in the proportions and dimensions of the various parts of the body ; the length of the legs being one of the most variable points.^ Although in some quarters of the world an elongated skull, and in other quarters a short skull prevails, yet there is great diversity of shape even within the limits of the same race, as with the aborigines of America and South Australia — the latter a race *' probably as " pure and homogeneous in blood, customs, and language as any " in existence" — and even with the inhabitants of so confined an area as the Sandwich Islands. ^ An eminent dentist assures me that there is nearly as much diversity in the teeth as in the features. The chief arteries so frequently run in abnormal courses, that it has been found useful for surgical purposes to calculate from 1040 corpses how often each course prevails.' The muscles are eminently variable : thus those of the foot were found by Prof. Turner * not to be strictly alike in any two out of fifty bodies ; and in some the deviations were considerable. * ' Investigations in Military and Huxley, in Lyell's ' Antiquity of Anthropolog. Statistics of American Man,' 1863,. p. 87. On the Sand- Soldiers,' by B. A. Gould, 1869, p. wich Islanders, Prof. J. Wyman, 256. ' Observations on Crania,' Boston, 2 With respect to the "Cranial 1868, p. 18. forms of the American aborigines," ' 'Anatomy of the Arteries,' by see Dr. Aitken Meigs in ' Proc. R. Quain. Preface, vol. i. 1844. Acad. Nat. Sci.' Philadelphia, May, * 'Transact. Royal Soc. Edin- 1868. On the Australians, see burgh,' vol. xxiv. pp. 175, 189. Chap. II. Maimer of Development. 2^ He adds, that the power of performing the appropriate move- ments must have been modified in accordance with the several deviations. Mr. J. Wood has recorded^ the occurrence of 295 muscular variations in thirty-six subjects, and in another set of the same number no less than 558 variations, those occurring on both sides of the body being only reckoned as one. In the last set, not one body out of the thirty-six was " found totally " wanting in departures from the standard, descriptions of the " muscular sj^stem given in anatomical text books." A single body presented the extraordinary number of twenty-five distinct abnormalities. The same muscle sometimes varies in many ways: thus Prof. Macalister describes*^ no less than twenty distinct variations in the jpalmaru accessor ins. The famous old anatomist, Wolff,'^ insists that the internal viscera are more variable than the external parts : Nulla jparti- cala est qux non aliter et aliter in aliis se habeat hominibus. He has even written a treatise on the choice of typical examples of the viscera for representation. A discussion on the beau-ideal of the liver, lungs, kidneys, &c., as of the human face divine, sounds strange in our ears. The variability or diversity of the mental faculties in men of the same race, not to mention the greater differences between the men of distinct races, is so notorious that not a word need here be said. So it is with the lower animals. All who have had charge of menageries admit this fact, and we see it plainly in our dogs and other domestic animals. Brehm especially insists that each individual monkey of those which he kept tame in Africa had its own peculiar disposition and temper ; he men- tions one baboon remarkable for its high intelligence ; and the keepers in the Zoological Gardens pointed out to me a monkey, belonging to the New World division, equally remarkable for intelligence. Eengger, also, insists on the diversity in the various mental characters of the monkeys of the same species which he kept in Paraguay ; and this diversity, as he adds, is partly innate, and partly the result of the manner in which they have been treated or educated.^ I have elsewhere^ so fully discussed the subject of Inheritance, that I need here add hardly anything. A greater number of 5 'Pioc. Royal Soc' 1867, p. » Brehm, ' Thierleben,' B. i. s. 544 ; also ] 868, pp. 48.'3, 524. There 58, 87. Kengger, ' Saugethiere von is a previous paper, 1866, p. 229. Paraguay,' s. 57. * ' Proc. R. Irish Academy,' vol. ' ' Variation of Animals an^ X. 1868, p. 141. Plants under Domestication,' vol ^ 'Act. Acad. St. Petersburg,* ii. chap. xii. 1778, part ii. p. 217 28 The Descent of Man. Part L facts have been collected with respect to the transmission of the most trifling, as well as of the most important characters in man, than in any of the lower animals; though the facts are copious enough with respect to the latter. So in regard to mental qualities, their transmission is manifest in our dogs, horses, and other domestic animals. Besides special tastes and habits, general intelligence, courage, bad and good temper, &c., are certainly transmitted. With man we see similar facts in almost every family; and we now know, through the admirable labours of Mr. Galton,^°that genius which implies a wonderfully complex combination of high faculties, tends to be inherited; and, on the other hand, it is too certain that insanity and deteri- orated mental powers likewise run in families. With respect to the causes of variability, we are in all cases very ignorant; but we can see that in man as in the lower animals, they stand in some relation to the conditions to which each species has been exposed, during several generations. Domesticated animals vary more than those in a state of nature ; and this is apparently due to the diversified and changing nature of the conditions to which they have been subjected. In this respect the different races of man resemble domesticated animals, and so do the individuals of the same race, when inhabiting a very wide area, like that of America. We see the influence of diversified conditions in the more civilised nations; for the members belonging to different grades of rank, and following different occupations, present a greater range of character than do the members of barbarous nations. But the uniformity of savages has often been exaggerated, and in some cases can hardly be said to exist.^^ It is, nevertheless, an error to speak of man, even if we look only to the conditions to which he has been exposed, as " far more domesticated "^^ than any other animal. Some savage races, such as the Australians, are not exposed to more diversified conditions than are many species which have a wide range. In another and much more important respect, man differs widely from any strictly domesticated animal ; for his breeding has never long been controlled, either by methodical or unconscious selection. No race or body of men has been so '" * Hereditary Genius : an In- " man had an oval visage with fine quiry into its Laws and Conse- " features, and another was quite quences,' 1869. " Mongolian in breadth and pro- '* Mr. Bates remarks (' The Natu- " minence of cheek, spread of nos- ralist on the Amazons,' 1863, vol. ii. " trils, and obliquity of eyes." p. 159), with respect to the Indians ^^ Blumenbach, 'Treatises on An- of the same South American tribe, thropolog.' Eng. translat., 1865, p. *' no two of them were at all similar 205. " in the shape of the head ; one Chap. II. Manner of Developmefit 29 completely siibjugcated by other men, as that certain individuals should be preserved, and thus unconsciously selected, from some- how excelling in utility to their masters. Nor have certain male and female individuals been intentionally picked out and matched, except in the well-known case of the Prussian grena- diers ; and in this case man obeyed, as miglit have been ex- pected, the law of methodical selection ; for it is asserted that many tall men were reared in the villages inhabited by the grenadiers and their tall wives. In Sparta, also, a form of selec- tion was followed, for it was enacted that all children should be examined shortly after birth ; the well-formed and vigorous being preserved, the others left to perish.^' If we consider all the races of man as forming a single species, his range is enormous ; but some separate races, as the Americans and Polynesians, have very wide ranges. It is a well-known law that widely-ranging species are much more variable than species with restricted ranges ; and the variability of man may with more truth be compared with that of widely-ranging species, than with that of domesticated animals. Not only does variability appear to be induced in man and the lower animals by the same general causes, but in both the same parts of the body are affected in a closely analogous manner. This, has been proved in such full detail by Godron and ^' Mitford's 'History of Greece,' vigour of their children. The Gre- vol. i. p. 282. It appears also from cian poet, Theognis, who lived 550 a passage in Xenophon's ' Memora- B.C., clearly saw how important bilia,' B. ii. 4 (to which my atten- selection, if carefully applied, would tion has been called by the Rev. be for the improvement of mankind. J. N. Hoare), that it was a well He saw, likewise, that wealth often recognised principle with the Greeks, checks the proper action of sexual that men ought to select their wives selection. He thus writes : with a view to the health and " With kine and horses, Kurnus ! we proceed By reasonable rules, and choose a breed For profit and increase, at any price ; Of a sound stock, without detect or vice. But, in the daily matches that we make, The price is everything : for money's sake, Men marry : women are in marriage given ; The churl or ruffian, that in wealth has thriven, May match his oflspring with the proudest race : Thus everytliing is mix'd, noble and base ! If then in outward manner, form, and mind, You find us a degraded, motley kind, Wonder no more, my friend ! the cause is plain, And to lament the consequence is vain." (The Works of J. Hookham Frere, vol. ii. 1872, p. 334.) 30 TJie Descent of Mmi. Part I, Quatrefages, that I need here only refer to their works.^^ Mon- strosities, which graduate into slight variations, are likewise so similar in man and the lower animals, that the same classification and the same terms can be used for both, as has been shewn by Isidore Geoffroy St.-Hilaire.'^ In my work on the yariation of domestic animals, I have attemjDted to arrange in a rude fashion the laws of variation under the following heads : — The direct and definite action of changed conditions, as exhibited by all or nearly all the individuals of the same species, varying in the same manner under the same circumstances. The effects of the long-continued use or disuse of parts. The cohesion of homologous parts. The variability of multiple parts. Compenpation of growth ; but of this law I have found no good instance in the case of man. The effects of the mechanical pressure of one part on another ; as of the pelvis on the cranium of the infant in the womb. Arrests of development, leading to the diminution or suppression of parts. The reappearance of long-lost characters through reversion. And lastly, correlated variation. All these so-called laws apply equally to man and the lower animals ; and most of them even to plants. It would be superfluous here to discuss all of them ;^^ but several are so important, that they must be treated at con- siderable length. The direct and definite action of changed conditions. — This is a most perplexing subject. It cannot be denied that changed con- ditions produce some, and occasionally a considerable effect, on organisms of all kinds ; and it seems at first probable that if sufficient time were allowed this would be the invariable result. But 1 have failed to obtain clear evidence in favour of this con- clusion ; and valid reasons may be urged on the other side, at least as far as the innumerable structures are concerned, which are adapted for special ends. There can, however, be no doubt that changed conditions induce an almost indefinite amount of fluctuating variability, by which the whole organisation is rend- ered in some degree plastic. In the United States, above 1,000,000 soldiers, who served in the late war, were measured, and the States in which they were ^'* Godron, 'De I'Espece,' 1859, '^ I have fully discussed these torn. ii. livre 3. Quatrefages, ' Unite laws in my * Variation of Animals de I'Espece Humaine,' 1861. Also and Plants under Domestication,' Lectures on Anthropology, given in vol. ii. chap. xxii. and xxiii. M. J. the ' Revue des Cours Scientifiques,' P. Durand has lately (1868) pub- 1886-1868. lished a valuable essay ' De I'ln- '* ' Hist. Gen. et Part, des Ano- fluence des Milieux,' &c. He lays malies de I'Organisation,' in three much stress, in the case of plants, on volumes, tom. i. 1832. the nature of the soil. Chap.it. Manner of Dcvelopiuciit. 31 born and reared were recorded.'^ From this astonishing number of observations it is proved tlmt local influences of some kind act directly on stature ; and we further learn that " the State " where the physical growth has in great measure taken place, " and the State of birth, which indicates the ancestry, seem to " exert a marked influence on the stature." For instance, it is established, " that residence in the Western States, during the " years of growth, tends to produce increase of stature." On the other hand, it is certain that with sailors, their life delays growth, as shewn '' by the great difference between the statures of soldiers " and sailors at the ages of seventeen and eighteen years." Mr. B. A. Gould endeavoured to ascertain the nature of the influences which thus act on stature ; but he arrived only at negative results, namely, that they did not relate to climate, the elevation of the land, soil, nor even " in any controlling degree " to the abundance or the need of the comforts of life. This latter conclusion is directly opposed to that arrived at by Villerme, from the statistics of the height of the conscripts in different parts of France. When we compare the differences in stature between the Polynesian chiefs and the lower orders within the same islands, or between the inhabitants of the fertile volcanic and low barren coral islands of the same ocean,^^ or again between the Fuegians on the eastern and western shores of their country, where the means of subsis- tence are very different, it is scarcely possible to avoid the con- clusion that better food and greater comfort do influence stature. But the preceding statements shew how difficult it is to arrive at any precise result. Dr. Beddoe has lately proved that, with the inhabitants of Britain, residence in towns and certain occupa- tions have a deteriorating influence on height ; and he infers that the result is to a certain extent inherited, as is likewise the case in the United States. Dr. Beddoe further believes that wherever a " race attains its maximum of physical development, it rises " highest in energy and moral vigour." ^^ Whether external conditions produce any other direct effect on man is not known. It might have been expected that dif-^ ferences of climate would have had a marked influence, in as much as the lungs and kidneys are brought into activity under a low " 'Investigations in Military and 289. There is also a remarkable Anthrop. Statistics,' &c. 1869, by ditlerence in appearance between B. A. Gould, p. 93, 107, 126, 131, the closely-allied Hindoos inhabiting 134. the Upper Ganges and Bengal ; see '* For the Polynesians, see Prich- Elphinstone's ' History of India,' vol. ard's ' Physical Hist, of Mankind,' i. p. 324. vol. v. 1847, p. 145, 283. Also '^ ' Memoirs, Anthropolog. Soc. Godron, ' De I'Espfece,' torn. ii. p. vol. iii. 1867-69, pp. 561, 565, 567. 32 The DesceJtt of Man. Part I. temperature, and the liver and skin under a high one.^ It was formerly thought that the colour of the skin and the character of the hair were determined by light or heat ; and although it can hardly be denied that some effect is thus produced, almost all observers now agree that the effect has been very small, even after exposure during many ages. But this subject will be more properly discussed when we treat of the different races of man- kind. With our domestic animals there are grounds for believing that cold and damp directly affect the growth of the hair ; but I have not met with any evidence on this head in the case of man. Effects of the iucnased Use and Disuse of Paris. — It is well known that use strengthens the muscles in the individual, and complete disuse, or the destruction of the proper nerve, weakens them. When the eye is destroyed, the optic nerve often becomes atrophied. When an artery is tied, the lateral channels increase not only in diameter, but in the thickness and strength of their coats. When one kidney ceases to act from disease, the other increases in size, and does double work. Bones increase not only in thickness, but in length, from carrying a greater weight.^^ Different occupations, habitually followed, lead to changed proportions in various parts of the body. Thus it was ascertained by the United States Commission ^^ that the legs of the sailors employed in the late war were longer by 0'217 of an inch than those of the soldiers, though the sailors were on an average shorter men ; whilst their arms were shorter by I 09 of an inch, and therefore, out of proportion, shorter in relation to their lesser height. This shortness of the arms is apparently due to their greater use, and is an unexi^ected result : but sailors chiefly use their arms in pulling, and not in supporting weights. With sailors, the girth of the neck and the depth of the instep are greater, whilst the circumference of the chest, waist, and hips is less, than in soldiers. Whether the several foregoing modifications would become hereditary, if the same habits of life were followed during many generations, is not known, but it is probable. Eengger^^ attri- butes the thin legs and thick arms of the Payaguas Indians to 20 Dr. Brakenridge, ' Theory of Dr. Jaeger, " Ueber das Langen- Diathesis,' ' Medical Times,' June 19 wachsthum der Knochen," ' Jena- and July 17, 1869. ischen Zeitschrift,' B. v. Heft i. 2* I have given authorities f(ir " ' Investigations,' &c. By B. A. these several statements in my Gould, 1869, p. 288. * Variation of Animals under Do- ^3 t Saugethiere von Paraguay, mestication,' vol. ii. pp. 297-300. 1830, s. 4. Chap. II. Manner of Development. 33 successive generations liaring passed nearly their whole lives in canoes, with their lower extremities motionless. Other writers have come to a similar conclusion in analogous cases. According to Cranz/-^ who lived for a long time with the Esquimaux, " the " natives believe that ingenuity and dexterity in seal-catching " (their highest art and virtue) is hereditary ; there is really " somethiag in it, for the son of a celebrated seal-catcher will " distinguish himself, though he lost his father in childhood." But in this case it is mental aptitude, quite as much as bodily structure, which appears to be inherited. It is asserted that the hands of English labourers are at birth larger than those ot the gentry.-^ From the correlation which exists, at least in some cases,-^ between the development of the extremities and of the jaws, it is possible that in those classes which do not labour much with their hands and feet, the jaws would be reduced in size from this cause. That they are generally smaller in refined and civilised men than in hard-working men or savages, is certain. But with savages, as Mr. Herbert Spencer '""^ has remarked, the greater use of the jaws in chewing coarse, uncooked food, would act in a direct manner on the masticatory muscles, and on the bones to which they are attached. In infants, long before birth, the skin on the soles of the feet is thicker than on any other part of the body;-^ and it can hardly be doubted that this is due to the inherited effects of pressure during a long series of generations. It is familiar to every one that watchmakers and engravei-s are liable to be short-sighted, whilst men living much out of doors, and especially savages, are generally long-sighted.^^ Short- sight and long-sight certainly tend to be inherited.^'' The inferiority of Europeans, in comparison w^ith savages, in eye- sight and in the other senses, is no doubt the accumulated and transmitted effect of lessened use during many generations ; for Eengger^^ states that he has repeatedly observed Europeans, ^* 'History of Greenland,' Eng. ('Sanitary Memoirs of the War of translat. 17G7, vol. i. p. 230. the Rebellion,' 1869, p. 530), has 2^ ' Intermarriage.' By Alex, proved this to be the case ; and h«' Walker, 1838, p. 377. accounts for it by the ordinal v ^° 'The Variation of Animals range of vision in sailors being " n-- under Domestication,' vol. i, p. 173. " stricted to the length of the vcsm;! 27 I. Principles of Biology,' vol. i. " and the height of tlie masts." p. 455. ^° 'The Variation of Animals 28 Paget, ' Lectures on Surgical under Domestication,' vol. i. p. 8. Pathology,' vol. ii. 1853, p. 209. ^' ' Siingethiere von Paraguay,' 2^ It is a singular and unex- s. 8, 10. I have had good opportuui- pected fact that sailors are interior ties for observing the extraordinarv to landsmen in their mean distance power of eyesight in the Fuegians. of distinct vision. Dr. B. A. Gould See also Lawrence (' lectures on 34 T^he Descent of Alan. Part I, who had been brought up and spent their whole lives with the wild Indians, who nevertheless did not equal them in the sharp- ness of their senses. The same naturahst observes that the cavities in the skull for the reception of the several sense-organs are larger in the American aborigines than in Europeans ; and this probably indicates a corresponding difference in the dimen- sions of the organs themselves. Blumenbach has also remarked on the large size of the nasal cavities in the skulls of the American aborigines, and connects this fact with their remarkably acute power of smell. The Mongolians of the plains of Northern Asia, according to Pallas, have wonderfully perfect senses ; and Prichard believes that the great breadth of their skulls across the zygomas follows from their high]y-develox)ed sense-organs.^^ The Quechua Indians inhabit the lofty plateaux of Peru ; and Alcide d'Orbigny states ^^ that, from continually breathing a highly rarefied atmosphere, they have acquired chests and lungs of extraordinary dimensions. The cells, also, of the lungs are larger and more numerous than in Europeans. These observa- tions have been doubted ; but Mr. D. Forbes carefully measured many Aymaras, an allied race, living at the height of between 10,000 and 15,000 feet; and he informs me 2* that they differ conspicuously from the men of all other races seen by him in the circumference and length of their bodies. In his table of measurements, the stature of each man is taken at 1000, and the other measurements are reduced to this standard. It is here seen that the extended arms of the Aymaras are shorter than those of Europeans, and much shorter than those of Negroes. The legs are likewise shorter ; and they present this remarkable peculiarity, that in every Aymara measured, the femur is actually shorter than the tibia. On an average, the length of the femur to that of the tibia is as 211 to 252 ; whilst in two Europeans, measured at the same time, the femora to the tibiae were as 2'44 to 230; and in three Negroes as 258 to 211. The humerus is likewise shorter relatively to the forearm. This shortening of that part of the limb which is nearest to the body, appears to be, as suggested to me by Mr. Forbes, a case of compensation in Physiology,' &c., 1822, p. 404) on bach, vol. i. 1851, p. 311; for the this same subject. M. Giraud-Teulon statement by PaHas, a-o1. iv. 1844, has recently collected (' Revue des p. 407. Cours Scieutifiques,' 1870, p. 625) ^^ Quoted by Prichard, ' Re- a large and valuable body of evidence searches into the Phys. Hist, of Man- proving that the cause of short- kind,' vol. v. p. 463. sight, " Cest le travail assidu, de 34 ]\jj._ Forbes' valuable paper is pres." now published in the ' Journal of '2 Prichard, ' Phys. Hist, of Man- the Ethnological Sec. of London,* kind,' on the authoritv of F>lumen- new series, vnl. ii. 1870, p. 193. Chap. II. Manner of Devdopnient. 35 relation with the greatly increased length of the trunk. The Aymaras present some other singular points of structure, for instance, the very small projection of the heel. These men are so thoroughly acclimatised to their cold and lofty abode, that when formerly carried down by the Spaniards to the low eastern plains, and when now tempted down by high wages to the gold-washings, they suifer a frightful rate of mor- tality. Nevertheless Mr. Forbes found a few pure families which had survived during two generations : and he observed that they still inherited their characteristic peculiarities. But it was manifest, even without measurement, that these pecaharities had all decreased ; and on measurement, their bodies were found not to be so much elongated as those of the men on the high plateau ; wliilst their femora had become somewhat lengthened, as had their tibite, although in a less degree. The actual measurements may be seen by consulting Mr. Forbes's memoir. From these observations, there can, I think, be no doubt that residence during many generations at a great elevation tends, both directly and indirectly, to induce inherited modifications in the proportions of the body.^^ Although man may not have been much moiified during the latter- stages of his existence through the increased or de- creased use of parts, the facts now given shew that his liability in* this respect has not been lost ; and we positively know that the same law holds good with the lower animals. Consequently we may infer that when at a remote epoch the progenitors of man were in a transitional state, and were changing from quadrupeds into bipeds, natural selection would probably have been greatly aided by the inherited effects of the increased or diminished use of the different parts of the body. A rrests of Developmen f. — There is a difference between arrested development and arrested growth, for parts in the former state continue to grow whilst still retaining their early condition. Various riionstrosities come under this head ; and some, as a cleft-palate, are known to be occasionally inherited. It will suffice for our purpose to refer to the arrested brain-development of microcephalous idiots, as described in Yogt's memoir.''^ Their skulls are smaller, and the convolutions of the brain are less complex than in normal men. The frontal sinus, or the '^ Dr. Wilckens (' Landwirth- regions, have their frames modified, schaft. Wochenblatt,' No. 10, 1869) ^<* ' Me'moire sur les Microc6- has lately published an interesting phales,' 1867, jip. 50, 125, 169, 171, Essav shewing how domestic ani- 18-1-198. mals, which live in mountainous 36 The Descent of Man. Part I. projection over the eye-brows, is largely developed, and the jaws are prognathous to an " effrayant'^ degree ; so that these idiots somewhat resemble the lower types of mankind. Their in- telligence, and most of their mental faculties, are extremely feeble. They cannot acquire the power of speech, and are wholly incapable of prolonged attention, but are much given to imitation. They are strong and remarkably active, continually gambohng and jumping about, and making grimaces. They often ascend stairs on all-fours; and are curiously fond of climbing up furniture or trees. We are thus reminded of the delight shewn by almost all boys in climbing trees; and this again reminds us how lambs and kids, originally alpine animals, delight to frisk on any hillock, however small. Idiots also resemble the lower animals in some other respects ; thus several cases are recorded of their carefully smelling every mouthful of food before eating it. One idiot is described as often using his mouth in aid of his hands, whilst hunting for lice. They are often filthy in their habits, and have no sense of decency ; and several cases have been published of their bodies being re- markably hairy ."'^ Reversion. — Many of the cases to be here given, might have been introduced under the last heading. When a structure is arrested in its development, but still continues growing, until it closely resembles a corresponding structure in some lower and adult member of the same group, it may in one sense be considered as a case of reversion. The lower members in a group give us some idea how the common progenitor was probably constructed ; and it is hardly credible that a complex part, arrested at an early phase of embryonic development, should go on growing so as ultimately to perform its proper function, unless it had acquired such power during some earher state of existence, when the present exceptional or arrested structure was normal. The simple brain of a microcephalous idiot, in as far as it resembles that of an ape, may in this sense be said to offer a case of reversion.^^ There are other cases which come 3^ Prof. Laycock sums up the pp. 46-51. Pinel has also given a character of brute-like idiots by striking case of hairiness in an calling them theroid ; 'Journal of idiot. Mental Science,' July 1 863. Dr. ^* In my ' Variation of Animals Scott ('The Deaf and Dumb,' 2nd under Domestication ' (vol. ii. p. 57), edit., 1870, p. 10) has often ob- I attributed the not very rare cases served the imbecile smelling their of supernumerary mammae in women food. See, on this same subject, to reversion. I was led to this as a and on the hairmess of idiots, Dr. probable conclusion, by the additional Maudsley, ' Body and Mind,' 1870, mammae being generally placed Chap. II. Manner of Development, Z7 more strictly under oiir jiresent head of reversion. Certain structures, regularly occurring in the lower members of the group symmetrical!}' on the breast ; and more especially from one case, in whicii a single elHcient mamma occurred in the inguinal region of a woman, the daughter of another woman with supernumerary mam- mas. But I now find (see, for in- stance, Prof. Preyer, ' Der Kampf um das Dasein,' 1869, s. 45) that mamma: crraticcc occur in other situations, as on the back, in the armpit, and on the thigh ; the mammaj in this latter instance having given so much milk that the child was thus nourished. The pro- bability that the additional mammaj are due to reversion is thus much weakened ; nevertheless, it still seems to me probable, because two pairs are often found symmetrically on the breast ; and of this I myself have received information in several cases. It is well known that some Lemurs normally have two pairs of mammje on the breast. Five cases have been recorded of the presence of more than a pair of mammte (of course rudimentary) in the male sex of mankind ; see ' Journal of Anat. and Physiology,' 1872, p. 56, for a case given by Dr. Handyside, in which two brothers exhibited this peculiarity ; see also a paper by Dr. Bartels, in Pieichert's and du Bois Reymond's Archiv., 1872, p. 304. In one of the cases alluded to by Dr. Bartels, a man bore five mammas, one being medial and placed above the navel ; Meckel von Hemsbach thinks that this latter case is illustrated by a medial mamma occurring in certain Cheiroptera. On the whole, we may well doubt if additional mamma) would ever have been developed in both sexes of mankind, had not his early progenitors been provided with more than a single pair. In the above work (vol. ii. p, 12), I also attributed, though with much hesitation, the frequent cases of polydactylism in men to reversion. I was partly led to this through Prof. Owen's statement, that some of the Ichthyopterygia possess more than five digits, and therefore, as I supposed, had retained a primordial condition ; but Prof. Gegenbaur (^ Jenaischen Zeitschrift,' B. v. Heft o, s. 341), disputes Owen's conclu- sion. On the other hand, according to the opinion lately advanced by Dx'. Gunther on the paddle of Ceia- todus, which is provided with ar- ticulated bony rays on both sides of a central chain of bones, there seems no great difficulty in admit- ting that six or more digits on one side, or double the number on both sides, might reappear through re- version. I am informed by Dr. Zouteveen that there is a case on record of a man having twenty-four fingers and twenty-four toes ! I was chiefly led to the conclusion that the presence of supernumerary digits is due to reversion from the fact that such digits not only are strongly inherited, but have the power of regrowth after amputa- tion, like the normal digits of the lower vertebrata. This fact of their regrowth remains inexplicable, if the belief in reversion to some ex- tremely remote progenitor is re- jected. Arrested development and reversion are intimately connected, and thus the belief in reversion in the present case is to a certain ex- tent supported by the frequent, or almost constant, coincidence insisted on by Meckel and I. Geotfroy St.- Hilaire, between various arrests of development, such as cleft-palate, bifid uterus, cyclopean state of the eyes, &c., and the presence of ad- ditional digits (see, on this head, M. A. Pionjou, 'Types Primitifs des Mammiferes,' p. Gl ; and M. Ber- tillon, ' Valeur Phil. Hyp. du Trans- formisme '). It is, on the other hand, no real objection to the view here 2,S The Descent of Man. Pakt 1. to which man belongs, occasionally make their appearance in him, though not found in the normal human embryo; or, if normally present in the human embryo, they become abnormally developed, although in a manner which is normal in the lower members of the group. These remarks will be rendered clearer by the following illustrations. In yarious mammals the uterus graduates from a double organ, with two distinct orifices and two passages, as in the marsupials, into a single organ, which is in no way double, except from having a slight internal fold, as in the higher apes and man. The rodents exhibit a perfect series of gradations between these two extreme states. In all mammals the uterus is developed from two simple primitive tubes, the inferior portions of wliich form the cornua ; and it is, in the words of I)r. Farre, " by the coalescence of the two cornua at their lower " extremities that the body of the uterus is formed in man ; " while in those animals in which no middle portion of body '•' exists, the cornua remain un-united. As the development of " the uterus proceeds, the two cornua become gradually shorter, " until at length they are lost, or, as it were, absorbed into the " body of the uterus." The angles of the uterus are still produced into cornua, even so high up in the scale as the lower apes, and lemurs. Now in women, anomalous cases are not very infrequent, in which the mature uterus is furnished with cornua, or is partially divided into two organs; and such cases, according to Owen, repeat "the grade of concentrative development," attained by certain rodents. Here perhaps we have an instance of a simple arrest of embryonic development, with subsequent growth and perfect functional development ; for either side of the partially double uterus is capable of performing the proper office of gestation. In other and rarer cases, two distinct uterine cavities are formed, each having its proper orifice and passage.^^ No such stage is passed through during the ordinary development of the embryo, and it is difficult to beheve, though perhaps not impossible, that the two simple, minute, primitive tubes should know how (if such an expression may be used) to grow into two maintained that supernumerary di- ultimately prevail, gits are often present without any ^^ See Dr. A. Farre's well-known other structure being affected ; for article in the ' Cyclop, of Anat. and numerous cases could be given Phys.' vol. v. 1859, p. 642. Owen of single characters reappearing ' Anatomy of Vertebrates,' vol. iii. through reversion. On the whole, 1868, p. 687. Prof. Turner in I cannot but think that the view ' Edinburgh Medical Journal,' Feb. originally propounded by me %vill 1805. Chap. II. Manner of Development. 39 distinct uteri, each with a well-constructed orifice and passage, and each furnished with numerous muscles, nerves, glands and vessels, if they had not formerly passed through a similar course of development, as in the case of existing marsupials. No one will pretend that so perfect a structure as the abnormal double uterus in woman could be the result of mere chance. But the principle of reversion, by which a long-lost structure is called back into existence, might serve as the guide for its full develop- ment, even after the lapse of an enormous interval of time. Professor Canestrini, after discussing the foregoing and various analogous cases, arrives at the same conclusion as that just given. He adduces another instance, in the case of the malar bone,*" which, in some of the Quadrumana and other mammals, normally consists of two portions. This is its condition in the human foetus when two months old ; and through arrested develop- ment, it sometimes remains thus in man when adult, more especially in the lower prognathous races. Hence Canestrini concludes that some ancient progenitor of man must have had this bone normally divided into tvro portions, wiiich afterwards became fused together. In man the frontal bone consists of a single jDiece, but in the embryo, and in children, and in almost all the lower mammals, it consists of two pieces separated by a distinct suture. This suture occasionally persists more or less distinctly in man after maturity ; and more frequently in ancient than in recent crania, especially, as Canestrini has observed, in those exhumed from the Drift, and belonging to the brachyce- phalic type. Here again he comes to the same conclusion as in the analogous case of the malar bones. In this, and other instances presently to be given, the cause of ancient races approaching the lower animals in certain characters more frequently than do the modern races, appears to be, that the latter stand at a somewhat *° ' Annuario della Soc. dei Xatu- tected in about two per cent, of ralisti in Modena,' 1867, p. 83. adult skulls; he also remarks that Prof. Canestrini gives extracts on it more frequently occurs in pro- this subject from various authorities. gnathous skulls, not of the Aryan Laurillard remarks, that as he has race, than in others. See also G. found a complete similarity in the Delorenzi on the same subject ; ' Tre form, proportions, and connection of nuovi cast d' auomalia dell'osso, the two malar bones in several malare,' Torino, 1872. . Also, E. human subjects and in certain apes, Morselli, ' Sopra una rara anomalia he cannot consider this disposition dell' osso malare,' Modena, 1872. of the parts as simply accidental. Still more recently Gruber has Another paper on this same anomaly written a pamjjlilet on the division has been published by Dr. Saviotti ofthisboue. 1 give these references in the ' Gazzetta delle Cliniche,' because a reviewer, without any Turin, 1871, where he says that grounds or scruples, has thrown traces of the divij,ion mav be de- doubts on mv statements. 40 The Descent of Man. Part I. greater distance in the long line of descent from their early semi- human progenitors. Various other anomalies in man, more or less analogous to the foregoing, have been advanced by different authors, as cases of reversion; but these seem not a little doubtful, for we have to descend extremely low in the mammalian series, before we find such structures normally present.*^ In man, the canine teeth are perfectly efficient instruments for mastication. But their true canine character, as Owen*^ re- marks, " is indicated by the conical form of the crown, which ** terminates in an obtuse point, is convex outward and flat or " sub-concave within, at the base of which surface there is a " feeble prominence. The conical form is best expressed in the " Blelanian races, especially the Australian. The canine is more " deeply implanted, and by a stronger fang than the incisors." Nevertheless, this tooth no longer serves man as a special weapon for tearing his enemies or prey ; it may, therefore, as far as its proper function is concerned, be considered as rudimentary. In every large collection of human skulls some may be found, as Hackel^^ observes, with the canine teeth projecting considerably beyond the others in the same manner as in the anthropomorphous apes, but in a less degree. In these cases, open spaces between the teeth in the one jaw are left for the reception of the canines of the opposite jaw. An interspace of this kind in a Kaffir skull, figured by Wagner, is surprisingly wide.^* Considering how few are the ancient skulls which have been examined, compared to recent skulls, it is an interesting fact that in at least three cases the canines project largely; and in the Naulette jaw they are spoken of as enormous.*^ *' A whole series of cases is given if in any way serviceable, for in- by Isid. GeofFroy St.-Hilaire, ' Hist, stance, in shortening and simplifying des Anomalies,' torn. iii. p. 437. the course of development ? And A reviewer (' Journal of Anat. and again, why should not injurious ab- Physiology,' 1871, p. 366) blames normalities, such as atrophied or hj-- me much for not having discussed pertrophied parfs, which have no the numerous cases, which have relation to a former state of exist- been recorded, of various parts ar- ence, occur at an early period, as rested in their development. He well as during maturity ? says that, according to my theory, 4- ' Anatomy of Vertebrates,' vol. " every transient condition of an iii. 1868, p. 323. " organ, during its development, is *^ ' Generelle Morphologie,' 1866, " not only a means to an end, but B. ii. s. civ. " once was an end in itself." This *^ Carl Vogt's 'Lectures on Man,' does not seem to me necessarily to Eng. translat. 1864, p. 151. hold good. Why should not varia- ^^ C. Carter Blake, on a jaw tions occur during an early period from La Naulette, ' Anthropolog. of development, having no relation Keview,' 1867, p. 295. Schaaff- to -"pvprsion ; yet such variations hausen, iliid. 1868, p. 426. might be preserved and accumul.ite'l. Chap. II. Manner of Development. 41 Of the anthropomorphous apes the males alone have their canines fully developed ; but in the female gorilla, and in a less degree in the female orang, these teeth project considerably beyond the others; therefore the fact, of which I have been assured, that women sometimes have considerably projecting canines, is no serious objection to the belief that their occasional great development in man is a case of reversion to an ape-hke progenitor. He who rejects with scorn the belief that the shape of his own canines, and their occasional great development in other men, are due to our early forefathers having been pro- vided with these formidable weapons, will probably reveal, by sneering, the line of his descent. For though he no longer intends, nor has the power, to use these teeth as weapons, he will unconsciously retract his " snarling muscles" (thus named by Sir C. Bell),""' so as to expose them ready for action, like a dog prepared to fight. Many muscles are occasionally developed in man, which are proper to the Quadrumana or other mammals. Professor Ylacovich*' examined forty male subjects, and found a muscle, called by him the iscliio-pubic, in nineteen of them ; in three others there was a ligament which represented this muscle ; and in the remaining eighteen no trace of it. In only two out of thirty female subjects was this muscle developed on both sides, but in three others the rudimentary ligament was present. This muscle, therefore, appears to be much more common in the male than in the female sex ; and on the belief in the descent of man from some lower form, the fact is intelligible ; for it has been detected in several of the lower animals, and in all of these it serves exclusively to aid the male in the act of reproduction. Mr. J. Wood, in his valuable series of papers,"*^ has minutely described a vast number of muscular variations in man, which resemble normal striPctures in the lower animals. The muscles <« 'The Anatomy of Expression,' pp. 241, 24-2; vol. xv. 1867, p. 544; 1844, pp. 110, 131. vol. xvi. 1868, p. 524. I may here *' Quoted by Prof. Canestrini in add that Dr. Murie and Mr. St. the 'Annuario,' &c., 1867, p. 90. George Mivart have shewn in their ^^ These papers deserve careful Memoir on the Lemuroidea (• Tran- study by any one who desires to sact. Zoolog. Soc' vol. vii. 1869, learn how frequently our muscles p. '^%\ how extraordinarily variable vary, and in varying come to re- some of the muscles are in these semble those of the Quadrumana. animals, the lowest members of the The following references relate to Primates. Gi-adations, also, in the the few points touched on in my muscles leading to structures found text: ' Proc. Royal Soc. vol. xiv. in animals still lower in the scale, 1865, pp. 379-384; vol. xv. 186G, are numerous in tin? Lemuroidea. 42 The Descent of Man. Part I. ■which closely resemble those regularly present in our nearest allies, the Quadrumana, are too numerous to be here, even specified. In a single male subject, having a strong bodily frame, and well-formed skull, no less than seven muscular varia- tions were observed, all of which plainly represented muscles proper to various kinds of apes. This man, for instance, had on both sides of his neck a true and powerful " levator claviculce,'' such as is found in all kinds of apes, and which is said to occur in about one out of sixty human subjects."^ Again, this man had " a special abductor of the metatarsal bone of the fifth " digit, such as Professor Huxley and Mr. Flower have shewn " to exist uniformly in the higher and lower apes." I will give only two additional cases; the acromio-basilar muscle is found in all mammals below man, and seems to be correlated with a quadrupedal gait,^° and it occurs in about one out 0/ sixty human subjects. In the lower extremities Mr. Bradley ^^ found an abductor ossis metatarsi quinti in both feet of man ; this muscle had not up to that time been recorded in mankind, but is always present in the anthropomorphous apes. The muscles of the hands and arms— parts which are so eminently characteristic of man— are extremely liable to vary, so as to resemble the corresponding muscles in the lower animals.^^ Such resem- blances are either perfect or imperfect; yet in the latter case they are manifestly of a transitional nature. Certain variations are more common in man, and others in woman, without our being able to assign any reason. Mr. Wood, after describing numerous variations, makes the following pregnant remark: " Notable departures from the ordinary type of the muscular " structures run in grooves or directions, which must be taken " to indicate some unknown factor, of much importance to a " comprehensive knowledge of general and scientific anatomy."*^ *^ See also Prof. Macalister in able case of variation in the human ' Proc. R. Irish Academ}-,' vol. x. flexor poUicis longus, adds, " This 1868, p. 124. " remarkable example shews that ^" Mr. Champneys in ' Journal of " man may sometimes possess the Anat. and Phys.' Nov., 1871, p. 178. " arrangement of tendons of thumb 51 'Journal of Anat. and Phys.' "and fingers characteristic of the May, 1872, p. 421. "macaque; but whether such a *2 Prof, Macalister (ibid. p. 121) " case should be regarded as a has tabulated his observations, and " macaque passing upwards into a finds that muscular abnormalities " man, or a man passing downwards are most frequent in the fore-arms, " into a macaque, or as a congenital secondly, in the face, thirdly, in the " freak of nature, I cannot under- foot &c. " take to say." It is satisfactory *^ The Rev. Dr. Haughton, after to hear so capable an anatomist, giving (' Proc. R. Irish Academy,' and so embittered an opponent of June°27, 1864, p. 71o) a remark- evolutionism, admitting even the Chap. II. Manner of Development. 43 That this unknown factor is reTcrsion to a former state of existence may be admitted as in the highest degree probable.'^* It is quite incredible that a man should through mere accident abnormally resemble certain apes in no less than seven of his muscles, if there had been no genetic connection between them. On the other hand, if man is descended from some ape-like creature, no valid reason can be assigned why certain muscles should not suddenly reappear after an interval of many thou- sand generations, in the same manner as with horses, asses, and mules, dark-coloured stripes suddenly reappear on the legs, and shoulders, after an interval of hundreds, or more probably of thousands of generations. These various cases of reversion are so closely related to those of rudmientary organs given in the first chapter, that many of them might have been indifferently introduced either there or here. Thus a human uterus furnished with cornua may be said to represent, in a rudimentary condition, the same organ in its normal state in certain mammals. Some parts which are rudi- mentary in man, as the os coccyx in both sexes, and the mammee in the male sex, are always present ; whilst others, such as the supracondyloid foramen, only occasionally appear, and therefore might have been introduced under the head of reversion. These several reversionary structures, as well as the strictly rudi- mentary ones, reveal the descent of man from some lower form in an unmistakable manner. Correlated Variation. — In man, as in the lower animals, many structures are so intimately related, that when one part varies so does another, without our being able, in most cases, to -assign any reason. We cannot say whether the one i^art governs the other, or whether both are governed by some earlier developed possiibility of either of his first pro- closely the variations resemble the positions. Prof. Macalister has also normal muscles of the lower ani- describeJ (' Proc. R. Irish Acad.' mals. He sums up by remarking, vol. X. 1864, p. 138) variations in " It will be enough for my purpose the/ej:or/)oWiciS /on^M5, remarkable "if I have succeeded in shewing from their relations to the same " the more important forms whicli, muscle in the Quadrumann. " when occurring as varieties in the ^■* Since the first edition of this *' human subject, tend to exhibit in book appeared, Mr. Wood has pub- " a sufficiently marked manner what lished another memoir in the ' Phil. " may be considered as proofs and Transactions,' 1870, p. 83, on the " examples of the Darwinian prin- varieties of the muscles of the human " ciple of reversion, or law of in- neck, shoulder, and chest. He here " heritance, in this department ot shews how extremely variable these " anatomical science." muscles are, and how often and how 44 The Descent of Man. Part I. part. Various monstrosities, as I. Geoffroy repeatedly insists, are thus intimately connected. Homologous structures are par- ticularly liable to change together, as we see on the opposite sides of the body, and in the upper and lower extremities. Meckel long ago remarked, that when the muscles of the arm depart from their proper type, they almost always imitate those of the leg ; and so, conversely, with the muscles of the legs. The organs of sight and hearing, the teeth and hair, the colour of the skin and of the hair, colour and constitution, are more or less cor- related.^^ Professor Schaaffhausen first drew attention to the relation apparently existing between a muscular frame and the strongly-pronounced supra-orbital ridges, which are so characteristic of the lower races of man. Besides the variations which can be grouped with more or less probability under the foregoing heads, there is a large class of variations which may be provisionally called spontaneous, for to our ignorance they appear to arise without any exciting cause. It can, however, be shewn that such variations, whether consisting of slight individual differences, or of strongly-marked and abrupt deviations of structure, depend much more on the constitution of the organism than on the nature of the condi- tions to which it has been subjected.^^ Bate of Increase. — Civilised populations have been known under favourable conditions, as in the United States, to double their numbers in twenty-five years ; and, according to a calcula- tion by Euler, this might occur in a little over twelve years.^'^ At the former rate, the present population of the United States (thirty millions), would in 657 years cover the whole terraqueous globe so thickly, that four men would have to stand on each square yard of surface. The primary or fundamental check to the continued increase of man is the difficulty of gaining subsistence, and of living in comfort. We may infer that this is the case from what we see, for instance, in the United States, where subsistence is easy, and there is plenty of room. If such means were suddenly doubled in Great Britain, our number would be quickly doubled. With civilised nations this primary check acts chiefly by restraining marriages. The greater death-rate of infants in the poorest classes is also very important; as well as '* The authorities for these seve- my ' Variation of Animals and Plants ral statements are given in my under Domestication.' 'Variation of Animals under Do- *^ See the ever memorable 'Essay mestication,' vol. ii. pp. 320-335, on the Principle of Population,' by ^^ This whole subject has been the Rev. T. Malthus, vol. i. 1826, p, discussed in chap, xxiii. vol. ii. of 6, 517. Chap. U. jMajiucr of Dcvelopnieiit. 45 the gi-eatcr mortality, from various diseases, of the inhabitants of crowded and miserable houses, at all ages. The effects of severe epidemics and wars are soon counterbalanced, and more than counterbalanced, in nations placed under favourable conditions. Emigration also comes in aid as a temporary check, but, with the extremely poor classes, not to any great extent. There is reason to suspect, as Malthus has remarked, that the reproductive power is actually less in barbarous, than in civilised races. We know nothing positively on this head, for with savages no census has been taken; but from the concurrent testimony of missionaries, and of others who have long resided with such people, it appears that their families are usually small, and large ones rare. This may be partly accounted for, as it is believed, by the women suckling their infants during a long time ; but it is highly probable that savages, who often suffer much hardship, and who do not obtain so much nutritious food as civilised men, would be actually less prolific. I have shewn in a former work,^^ that all our domesticated quadrupeds and birds, and all our cultivated plants, are more fertile than the corresponding species in a state of nature. It is no valid objection to this conclusion that animals suddenly supplied with an excess of food, or when grown very fat ; and that most plants on sudden removal from very poor to very rich soil, are rendered more or less sterile. We might, therefore, expect that civilised men, who in one sense are highly domesticated, would be more prolific than wild men. It is also probable that the increased fertility of civilised nations would become, as with our domestic animals, an inherited character : it is at least known that with mankind a tendency to produce twins runs in families.^^ Notwithstanding that savages appear to be less prolific than civilised people, they would no doubt rapidly increase if their numbers were not by some means rigidly kept down. The San- tali, or hill-tril)es of India, have recently afforded a good illustra- tion of this fact ; for, as shewn by Mr. Hunter,*^ they have increased at an extraordinary rate since vaccination has been introduced, other pestilences mitigated, and war sternly repressed. This increase, however, would not have been possible had not these rude people spread into the adjoining districts, and worked for hire. Savages almost always marry ; yet there is some prudential restraint, for they do not commonly marry at the ** 'Variation of Animals, and Foreign Medico-Chirurg. Pieview,' Plants under Domestication,' vol. ii. July, 1863, p. 170. pp. 111-113, 163. «« ' The Annals of Rural Bengal,' " Mr. Sedgwick, 'British and bv \V. W. Hunter, 1868, p. 259. 46 The Descent of Man. Part I. earliest possible age. The young men are often required to shew that they can support a wife ; and they generally have first to earn the price with which to purchase her from her parents. With savages the difficulty of obtaining subsistence occasionally limits their number in a much more direct manner than with civilised people, for all tribes periodically suffer from severe famines. At such times savages are forced to devour much bad food, and their health can hardly fail to be injured. Many accounts have been published of their protruding stomachs and emaciated limbs after and during famines. They are then, also, compelled to wander much, and, as I was assured in Australia, their infants perish in large numbers. As famines are period- ical, depending chiefly on extreme seasons, all tribes must fluctuate in number. They cannot steadily and regularly increase, as there is no artificial increase in the supply of .food. Savages, when hard pressed, encroach on each other's territories, and war is the result ; but they are indeed almost always at war with their neighbours. They are liable to many accidents on land and water in their search for food ; and in some countries they sufi"er much from the larger beasts of prey. Even in India, districts have been depopulated by the ravages of tigers. Malthus has discussed these several checks, but he does not lay stress enough on what is probably the most important of all, namely infanticide, especially of female infants, and the habit of procuring abortion. These practices now prevail in many quarters of the world ; and infanticide seems formerly to have prevailed, as Mr. ]\['Lennan'^^ has shewn, on a still more extensive scale. These practices appear to have originated in savages re- cognising the difficulty, or rather the impossibility of supporting all the infants that are born. Licentiousness may also be added to the foregoing checks; but this does not follow from failing means of subsistence ; though there is reason to believe that in some cases (as in Japan) it has been intentionally encouraged as a means of keeping down the population. If we look back to an extremely remote epoch, before man had arrived at the dignity of manhood, he would have been guided more by instinct and less by reason than are the lowest savages at the present time. Our early semi-human progenitors would not have practised infanticide or polyandry ; for the instincts of the lower animals are never so perverted ^- as to lead them re- ** ' Primitive Marriage,' 1865. ments as follows on this passage : — ^^ A writer in the 'Spectator' " Mr. Darwin finds himself compelled (March 12th, 1871, p. 320) com- " to reintroduce a new doctrine of the Chap. II. Manner of Devclopuient. 47 gularly to destroy their own offspring, or to be quite devoid of jealousy. There would have been no prudential restraint from marriage, and the sexes would have freely united at an early age. Hence the progenitors of man would have tended to increase rapidly; but checks of some kind, either periodical or constant, must have kept down their numbers, even more severely than with existing savages. What the precise nature of these checks were, we cannot say, any more than with most other animals. We know that horses and cattle, which are not extremely prolific animals, when first turned loose in South America, increased at an enormous rate. The elephant, the slowest breeder of all known animals, would in a few thousand years stock the whole world. The increase of every species of monkey must be checked by some means; but not, as Brehm remarks, by the attacks of beasts of prey. No one w^ill assume that the actual power of reproduction in the wild horses and cattle of America, was at first in any sensible degree increased ; or that, as each district became fully stocked, this same power was diminished. No doubt in this case, and in all others, many checks concur, and different checks under different circumstances ; periodical dearths, depending on unfavourable seasons, being probably the most important of all. So it will have been with the early pro- genitors of man. Natural Selection. — We have now seen that man is variable in body and mind; and that the variations are induced, either directly or indirectly, by the same general causes, and obey the same general laws, as with the low^er animals. Man has spread widely over the face of the earth, and must have been exposed, during his incessant migrations,^^ to the most diversified con- ditions. The inhabitants of Tierra del Fuego, the Cape of Good Hope, and Tasmania in the one hemisphere, and of the Arctic regions in the other, must have passed through many climates, " fiill of man. He shews that the *' by the many foul customs, es- " instincts of the higher animals " pecially as to marriage, of savage " are far nobler than the habits of " tribes. What does the Jewish " savage races of men, and he finds " tradition of the moral degonera- " himself, therefore, compelled to " tion of man through his snatching " re-introduce, — in a form of the " at a knowledge forbidden him " substantial orthodoxy of which he " by his highest instinct a'^sert " appears to be quite unconscious, — " beyond this?" " and to introduce as a scientific ®^ See some good remarks to this " hypothesis the doctrine that man's effect by W. Stanley Jevons, " A " gain of knoicledje was the cause of " Deduction from Darwin's Theory," "a temporary but long-enduriug ' Nature,' 1869, p. 231. " moral deterioration, as indicated 48 TJie Descent of Man. Part I. and changed their habits many times, before they reached their present homes.®* The early progenitors of man must also have tended, like all other animals, to have increased beyond their means of subsistence they must, therefore, occasionally have been exposed to a struggle for existence, and consequently to the rigid law of natural selection. Beneficial variations of all kinds will thus, either occasionally or habitually, have been preserved, and injurious ones eliminated. I do not refer to strongly-marked deviations of structure, which occur only at long intervals of time, but to mere individual differences. We know, for instance, that the muscles of our hands and feet, which determine our powers of movement, are liable, hke those of the lower animals,^^ to incessant variability. If then the progenitors of man inhabit- ing any district, especially one undergoing some change in its conditions, were divided into two equal bodies, the one half which included all the individuals best adapted by their powers of movement for gaining subsistence, or for defending themselves, would on an average survive in greater numbers, and procreate more offspring than the other and less well endowed half. Man in the rudest state in which he now exists is the most dominant animal that has ever appeared on this earth. He has spread more widely that any other highly organised form : and all others have yielded before him. He manifestly owes this immense superiority to his intellectual faculties, to his social habits, wliich lead him to aid and defend his fellows, and to his corporeal structure. The supreme importance of these characters has been proved by the final arbitrament of the battle for life. Through his powers of intellect, articulate language has been evolved; and on this his wonderful advancement has mainly depended. As Mr. Chauncey Wright remarks :®s " a psychological " analysis of the faculty of language shews, that even the smallest " proficiency in it might require more brain power than the " greatest proficiency in any other direction.'' He has invented and is able to use various weapons, tools, traps, &c., with which he defends himself, kills or catches prey, and otherwise obtains food. He has made rafts or canoes for fishing or crossing over to neighbouring fertile islands. He has discovered the art of ^* Latham, ' Man and his Migra- " classed in any of the above tions,' 1851, p. 135. " groups." These muscles differ •^^ Messrs. Murie and Mivart in even on the opposite sides of the their 'Anatomy of the Lemuroidea' same individual. (' Transact. Zoolog. Soc' vol. vii. ^^ Limits of Natural Selection, 1869, pp. 96-98) say, "some- muscles 'North American Review,' Oct. " are so irregular in their distribu- 1870, p. 295. " tion that" they cannot be well Chap. II. Manner of Develcpmeiit. 49 making fire, by wliicli hard and stringy roots can be rendered digestible, and poisonous roots or herbs innocuous. This dis- covery of fire, probably the greatest ever made by man, excepting language, dates from before the dawn of history. These several inventions, by wliich man in the rudest state has become so pre- eminent, are the direct results of the development of his powers of observation, memory, curiosity, imagination, and reason. I cannot, therefore, understand how it is that Mr. Wallace" main- tains, that ** natural selection could only have endowpd the " savage with a brain a little superior to that of an ape." Although the intellectual powers and social habits of man are of paramount importance to him, we must not underrate the importance of his bodily structure, to which subject the remain- der of this chapter will be devoted ; the development of the in- tellectual and social or moral faculties being discussed in a later chapter. Even to hammer with precision is no easy matter, as every one who has tried to learn carpentry will admit. To throw^ a stone with as true an aim as a Fuegian in defending himself, or in killing birds, requires the most consummate perfection in the correlated action of the muscles of the hand, arm, and shoulder, and, further, a fine sense of touch. In throwing a stone or spear, and in many other actions, a man must stand firmly on his feet ; and this again demands the perfect co-adaptation of numerous muscles. To chip a flint into the rudest tool, or to form a barbed spear or hook from a bone, demands the use of a perfect hand ; for, as a most capable judge, Mr. Schoolcraft,^^ remarks, the shaping fragments of stone into knives, lances, or arrows-heads, °^ ' Quarterly Review,' April hoi-e resist quoting a most just 1869, p. 392. 'This subject is more remark by Sir J. Lubbock (' Pre- fuUy discussed in Mr. Wallace's historic Times,' 1865, p. 479) in ' Contributions to the Theory of reference to this paper, namely, that Natural Selection,' 1870, in which Mr. Wallace, "with characteristic all the essays referred lo in this " unselfishness, ascribes it (i. e. the work are republished. The ' Essay " idea of natural selection) unre- on Man ' has been ably criticised by " servedly to Mr. Darwin, although, Prof. Claparede, one of the most " as is well known, he struck out distinguished zoologists in Europe, " the idea independently, and pub- in an article published iu the " lished it, though not with the ' Bibliotheque Universelle,' June " same elaboration, at the same 1870. The remark quoted in my " time." text will surprise every one who ®* Quoted by Mr. Lawson Tait in has read Mr. Wallace's celebrated his ' Law of Natural Selection,' — paper on 'The Origin of Human ' Dublin Quarterly Journal of Modi- Races deduced from the Theory of cal Science,' Feb. 1869. Dr. Keller Natural Selection,' originally pub- is likewise quoted to the same lished in the ' Anthropological Re- effect, view,' !^L^y 1864, p. chili. I cannot 50 The Descent of Man. Part I. shews " extraordinary ability and long practice." This is to a great extent proved by the fact that primeyal men practised a division of labour; each man did not manufacture his own flint tools or rude pottery, but certain individuals appear to have devoted themselves to such work, no doubt receiving in exchange the produce of the chase. Archaeologists are convinced that an enormous interval of time elapsed before our ancestors thought of grinding chipped flints into smooth tools. One can hardly doubt, that a man-like animal who possessed a hand and arm sufficiently perfect to throw a stone with precision, or to form a flint into a rude tool, could, with sufficient joractice, as far as mechanical skill alone is concerned, make almost anything which a civilised man can make. The structure of the hand in this respect may be compared with that of the vocal organs, which in the apes are used for uttering various signal-cries, or, as in one genus, musical cadences; but in man the closely similar vocal organs have become adapted through the inherited eifects of use for the utterance of articulate language. Turning now to the nearest aUies of men, and therefore to the best representatives of our early progenitors, we find that the hands of the Quadrumana are constructed on the same general pattern as our own, but are far less perfectly adapted for diver- sified uses. Their hands do not serve for locomotion so well as the feet of a dog ; as may be seen in such monkeys as the chimpanzee and orang, which walk on the outer margins of the palms, or on the knuckles. ^^ Their hands, however, are acbnirably adapted for climbing trees. Monkeys seize thin branches or ropes, with the thumb on one side and the fingers and jDalm on the other, in the same manner as we do. They can thus also lift rather large objects, such as the neck of a bottle, to their mouths. Baboons turn over stones, and scratch up roots with their hands. They seize nuts, insects, or other small objects with the thumb in opposition to the fingers, and no doubt they thus extract eggs and the young from the nests of bii'ds. American monkeys beat the wild oranges on the branches until the rind is ci-acked, and then tear it off with the fingers of the two hands. In a wild state they break open hard fruits with stones. Other monkeys open mussel-shells with the two thumbs- With their fingers they pull out thorns and burs, and hunt for each other's parasites. They roll down stones, or throw them at their enemies : nevertheless, they are clumsy in these various actions, and, as I have myself seen, are quite unable to tlirow a stone with precision, *^ Owen, Anatomy of Vertebrattis/ vol. iii. p. 71. CiiAi II. Manner of Development. 51 It seems to me far from true that because " objects are grasped " clumsily " by monkeys, " a much less specialised organ of " prehension " would have served them ''" equally "well with their present hands. On the contrary, I see no reason to doubt that more perfectly constructed hands would have been an advantage to them, provided that they were not thus rendered less fitted for climbing trees. We may suspect that a hand as perfect as that of man would have been disadvantageous for climbing; for the most arboreal monkeys. iii the world, namely, Ateles in America, Colobus in Africa, and Hylobates in Asia, are either thumbless, or their toes partially cohere, so that their limbs are converted into mere grasping hooks,'^ As soon as some oncient member in the great series of the Primates came to be less arboreal, owing to a change in its manner of procuring subsistence, or to some change in the surrounding conditions, its habitual manner of progression would have been modified : and thus it would have been rendered more strictly quadrupedal or bipedal. Baboons frequent hilly and rocky districts, and only from necessity climb high trees ; '- and they have acquired almost the gait of a dog. Man alone has become a biped ; and we can, I think, partly see how he has come to assume his erect attitude, which forms one of his most conspicuous characters. Man could not have attained his present dominant posijtion in the world without the use of his hands, which are so admirably adapted to act in obedience to his will. Sir C. Bell "^ insists that " the hand supplies all instruments, " and by its correspondence with the intellect gives him univer- " sal dominion." But the hands and arms could hardly have become perfect enough to have manufactured weapons, or to have hurled stones and sj)ears with a true aim, as long as they were habitually used for locomotion and for supporting the whole weight of the body, or, as before remarked, so long as they were especially fitted for climbing trees. Such rough treatment would also have blunted the sense of touch, on which their delicate use largely depends. From these causes alone it would have been an advantage to man to become a biped; but for ^0 ' Quarterly Review,' April but whether a better climber than 1869, p. 392. the species of the allied genera, 1 do '1 In IrLjlohntcs siindactylus, as not know. It deserves notice that the name expresses, two of the toes the feet of the sloths, the most regularly cohere ; and this, as Mr. arboreal animals in the world, are Blyth informs me, is occasionally wonderfully hook-like, the case with the toes of H. a(]ilis, " Brehm, ' Thierlobon,' B. i. s, /a;-, and /eucj'scMS. Colobus is strictly 80. arboreal and extraordinarily active "' ''The Hand," <&:c. * Bridge- (Brehm, ' Thierleben,' B. i. s. 50), water Treatise,' 1833, p. 38. 52 The Descent of Man. Part I. many actions it is indispensable that the arms and whole upper part of the body should be free ; and he must for this end stand firmly on his feet. To gain this great advantage, the feet have been rendered flat ; and the great toe has been peculiarly modi- fied, though this has entailed the almost complete loss of its power of prehension. It accords with the principle of the division of physiological labour, prevailing throughout the animal kingdom, that as the hands became perfected for i^re- hension, the feet should have become perfected for support and ■ locomotion. "With some savages, however, the foot has not altogether lost its prehensile power, as shewn by their manner of climbing trees, and of using them in other ways.'^* If it be an advantage to man to stand firmly on his feet and to have his hands and arms free, of which, from his pre-eminent success in the battle of life, there can be no doubt, then I can see no reason why it should not have been advantageous to the progenitors of man to have become more and more erect or bipedal. They would thus have been better able to defend themselves with stones or clubs, to attack their prey, or other- wise to obtain food. The best built individuals would in the long run have succeeded best, and have survived in larger numbers. If the gorilla and a few allied forms had becomn. extinct, it might have been argued, with great force and apparent truth, that an animal could not have been gradually converted from a quadruped into a biped, as all the individuals in an intermediate condition would have been miserably ill-fitted for progression. But we know (and this is well worthy of reflection) that the anthropomorphous apes are now actually in an intermediate condition ; and no one doubts that they are on the whole well adapted for their conditions of life. Thus the gorilla runs with a sidelong shambling gait, but more commonly progresses by resting on its bent hands. The long-armed apes occasionally use their arms like crutches, swinging their bodies forward between them, and some kinds of Hylobates, without having been taught, can walk or run upright with tolerable quickness ; yet they move awkwardly, and much less securely than man. We see, in short, in existing monkeys a manner of progression intermediate between that of a quadruped and a ^* Hackel has an excellent dis- foot as a prehensile organ by man ; cussion on the steps by which man and has also written on the manner became a biped: ' Natiirliche Schop- of progression of the higher apes, to fungsgeschichte,' 1868, s. 507. Dr. Avhich I allude in the following Biichner (' Conferences sur la Theorie paragraph : see also Owen (' Anatomy Darwinienne,' 1869, p. 135) has of Vertebrates,' vol, iii. p. 71) on given good cases of the use of the this latter subject. C: H A p. I r . Manner of Developnien t. 53 biped ; but, as an unprejudiced judge '^ insists, the anthropomor- phous apes approach in structure more nearly to the bipedal than to the quadrupedal type. As the progenitors of man became more and more erect, with their hands and arms more and more modified for prehension and other purposes, with their feet and legs at the same time transformed for firm support and progression, endless other changes of structure would have become necessary. The pelvis •would have to be broadened, the spine peculiarly curved, and the head fixed in an altered position, all which changes have been attained by man. Prof. Schaaflihausen " maintains that "the " powerful mastoid processes of the human skull are the result of " his erect position ;" and these processes are absent in the orang, chimpanzee, &c., and are smaller in the gorilla than in man. Various other structures, which appear connected with man's erect position, might here have been added. It is very difficult to decide how far these correlated modifications are the result of natural selection, and how far of the inherited effects of the increased use of certain parts, or of the action of one part on another. No doubt these means of change often co-operate : thus when certain muscles, and the crests of bone to which they are attached, become enlarged by habitual use, this shews that certain actions are habitually performed and must be serviceable. Hence the individuals which performed them best, would tend to survive in greater numbers. The free use of the arms and hands, partly the cause and partly the result of man's erect position, appears to have led in an indirect manner to other modifications of structure. The early male forefathers of man were, as previously stated, jDrobably furnished with great canine teeth; but as they gradually acquired the habit of using stones, clubs, or other weaj^ons, for fighting with their enemies or rivals, they would use their jaws and teeth less and less. In this case, the jaws, together with the teeth, w^ould become reduced in size, as we may feel almost sure from innumerable analogous cases. In a future chapter we shall meet with a closely parallel case, in the reduction or com- plete disappearance of the canine teeth in male ruminants, apparently in relation with the development of their horns ; and in horses, in relation to tlieii' habit of fighting with their incisor teeth and hoofs. " Prof. Broca, La Constitution the Skull,' translated iu ' Authro- des Vertfebres ciiudales; 'La Revue pological Review,' Oct. 18*38, p. d'Anthropologie,' 1872, p. iG, 428. Owen (' Anatomy of Verte- (separate copy) brates,' vol. ii. 1866, p. 551) on the '•^ 'On the rrimitive Form of mastoid processes in the higher apes. 54 The Descent of Man. Tart I. In the adult male anthropomorphous apes, as Eutimeyer/''" and others, have insisted, it is the effect on the skull of the great development of the jaw-muscles that causes it to differ so greatly in many respects from that of man, and has given to these animals " a truly frightful physiognomy." Therefore, as the jaws and teeth in man's progenitors gradually became reduced in size, the adult skull would have come to resemble more and more that of existing man. As we shall hereafter see, a great reduction of the canine teeth in the males would almost certainly affect the teeth of the females through inheritance. As the various mental faculties gradually developed themselves the brain would almost certainly become larger. No one, I presume, doubts that the large proportion which the size of man's brain bears to his body, compared to the same proportion in the gorilla or orang, is closely connected vfith his higher mental powers. We meet with closely analogous facts with insects, for in ants the cerebral ganglia are of extraordinary dimensions, and in all the Hymenoptera these ganglia are many times larger than in the less intelligent orders, such as beetles. '^^ On the other hand, no one supposes that the intellect of any two animals or of any two men can be accurately gauged by the cubic contents of their skulls. It is certain that there may be extraordinary mental activity with an extremely small absolute mass of nervous matter: thus the wonderfully diversified instincts, mental powers, a-nd affections of ants are notorious, yet their cerebral ganglia are not so large as the quarter of a small pin's head. Under this point of view, the brain of an ant is one of the most marvellous atoms of matter in the world, perhaps more so than the brain of a man. The belief that there exists in man some close relation between the size of the brain and the development of the intellectual faculties is supported by the comparison of the skulls of savage and civilised races, of ancient and modern people, and by the analogy of the whole vertebrate series. Dr. J. Barnard Davis has proved,'^^ by many careful measurements, that the mean internal capacity of the skull in Europeans is 92-3 cubic inches; in Americans 87-5; in Asiatics 871 ; and in Australians only 81-9 - cubic inches. Professor Broca ^^ found that the nineteenth century ^^ 'Die Grenzen der Thierwelt, vomitoria* 1870, p. 14. Mv son, oine Betrachtung zu Darwin's Lehre,' Mr. F. Darwin, dissected for ine the 1868, s. 51. cerebral ganglia of the Formica ^^ Dujardin, ' Annales des Sc. rttfa. Nat,' 3rd series Zoolog. torn, xiv. ''^ < Philosophical Transactions, 1850, p. 203. See also Mr. Lowne, 1869, p. 513. 'Anatomy and Phys. of the 3Imca 8<> ' Les Selections,' M. P. Broca, Cji A P. I [ . Manner of Development, 5 5 skulls from graves in Paris were larger than those from -vaults of the twelfth century, in the proportion of 1-184 to 1426 ; and that the increased size, as ascertained by measurements, was exclusively in the frontal part of the skull — the seat of the intellectual faculties. Prichard is persuaded that the present inhabitants of Britain have " much more capacious brain-cases " than the ancient inhabitants. Nevertheless, it must be admitted that some skulls of very high antiquity, such as the famous one of Neanderthal, are well developed and capacious.^^ With respect to the lower animals, M. E. Lartet,^- by comparing the crania of tertiary and recent mammals belonging to the same groups, has come to the remarkable conclusion that the brain is generally larger and the convolutions are more complex in the more recent forms. On the other hand, I have shewn^^ that the brains of domestic rabbits are considerably reduced in bulk, in comparison with those of the wild rabbit or hare ; and this may be attributed to their having been closely confined during many generations, so that they have exerted their intellect, instincts, senses and voluntary movements but little. The gi'adually increasing weight of the brain and skull in man must have influenced the development of the supporting spinal column, more especially whilst he was becoming erect. As this change of iDOsition was being brought about, the internal pressure of the brain will also have influenced the form of the skull ; for many facts show how easily the skull is thus affected. Ethnologists believe that it is modified by the kind of cradle in which infants sleep. Habitual spasms of the muscles, and a cicatrix from a severe burn, have permanently modified the facial bones. In young persons whose heads have become fixed either sideways or backwards, o\ving to disease, one of the two eyes has changed its position, and the shape of the skull has been altered ' Revue d'Anthropologies,' 1873 ; the other hand, with savages, the ave- see also, as quoted in C. Vogt's rage includes only the more capable ' Lectures on Man,' Eng. translat. individuals, who have been able to 1864, pp. 88, 90. Prichard, ' Phys. survive under extremely hard con- Hist. of Mankind,' vol. i. 1838, p. ditions of lite. Broca thus explains 305, the otherwise inexplicable fact, that *' In the interecting article just the mean capacity of the skull of referred to. Prof. Broca has well the ancient Troglodytes of Lozere is remarked, that in civilised nations, greater than that ot modern French- the average capacity of the skull men. must be lowered by the preserva- "- ' Comptes-rendus des Sciences,' tion of a considerable number of (Sec. June 1, 18G8. individuals, weak in mind aud body, ^^ 'The Variation of Animals and who would have been promptly Plants under Domestication,' vol. i. eliminated in the savage state. On pp. 124-129. 56 The Descent of Man. Part I. apparently by the pressure of the brain in a new direction.^* I have shewn that with long-eared rabbits even so trifling a cause as the lopping forward of one ear drags forward almost every bone of the skull on that side ; so that the bones on the opposite side no longer strictly correspond. Lastly, if any animal were to increase or diminish much in general size, without any change in its mental powers, or if the mental powers were to be much increased or diminished, without any great change in the size of the body, the shape of the skull would almost certainly be altered. I infer this from my observations on domestic rabbits, some kinds of which have become very much larger than the wild animal, whilst others have retained nearly the same size, but in both cases the brain has been much reduced relatively to the size of the body. Now I was at first much sui'prised on finding that in all these rabbits the skull had become elongated or dolichocephalic; for instance, of two skulls of nearly equal breadth, the one from a wild rabbit and the other from a large domestic kind, the former was 3-15 and the latter 4-3 inches in length.^5 One of the most marked distinctions in difierent races of men is that the skull in some is elongated, and in others rounded; and here the explanation suggested by the case of the rabbits may hold good; for Welcker finds that short "men incline more " to brachycephaly, and tall men to dolichocephaly ;"^^ and tall men may be compared with the larger and longer-bodied rabbits, all of which have elongated skulls, or are dolicho- cephalic. From these several facts we can understand, to a certain extent, the means by which the great size and more or less rounded form of the skull have been acquired by man ; and these are characters eminently distinctive of him in comparison with the lower animals. Another most conspicuous difference between man and the lower animals is the nakedness of his skin. Whales and porpoises (Cetacea), dugongs (Sirenia) and the hippopotamus are naked; and this may be advantageous to them for gliding ** SchaafFhausen gives fi-om Blu- maker, where the head is habitually menbach and Busch, the cases of the held forward, the forehead becomes spasms and cicatrix, in 'Anthro- more rounded and })rominent. polog. Review,' Oct. 1868, p. 420. ^^ 'Variation of Animals,' &c., Dr. Jarrold (' Anthropologia,' 1808, vol. i. p. 117, on the elongation of pp. 115, 116) adduces from Camper the skull; p. 119, on the efi'ect of and from his own observations, cases the lopping of one ear. of the modification of the skull from ^"^ Quoted by Schaaffhausen, in the head being fixed in an unnatural ' Anthropolog. Review,' Oct. 18G8, position. He believes that in cer- p. 419. t.iin trades, such as that of a shoe- Chap. II. Maimer of Development. 57 through the water ; nor would it be injurious to them from the loss of warmth, as the species, which inhabit the colder regions, are protected by a thick layer of blubber, serving the same purpose as the fur of seals and otters. Elephants and rhino- ceroses are almost hairless ; and as certain extinct species, which formerly lived under an Arctic climate, were covered with long wool or hair, it would almost appear as if the existing species of both genera had lost their hairy covering from exposure to heat. This appears the more probable, as the elephants in India which live "on elevated and cool districts are more hairy ^^ than those on the lowlands. May we then infer that man became divested of hair from having aboriginally inhabited some tropical land ? That the hair is chiefly retained in the male sex on the chest and face, and in both sexes at the junction of all four limbs with the trunk, favours this inference — on the assumption that the hair was lost before man became erect ; for the parts which now retain most hair would then have been most protected from the heat of the sun. The crown of the head, however, offers a curious exception, for at all times it must have been one of the most exposed parts, yet it is thickly clothed with hair. The fact, however, that the other members of the order of Primates, to which man belongs, although inhabiting various hot regions, are well clothed with hair, generally thickest on the upper surface,*^ is o^Dposed to the supposition that man became naked through the action of the sun. Mr. Belt believes ^^ that within the tropics it is an advantage to man to be destitute of hair, as he is thus enabled to free himself of the multitude of ticks (acari) and other jDarasites, with which he is often infested, and which sometimes cause ulceration. But whether this evil is of sufficient magnitude to have led to the denudation of his body through natural selection, may be doubted, since none of the many quadrupeds inhabiting the tropics have, as far as I know, acquired any specialised means of relief. The view which seems to me the most probable is that man, or rather primarily woman, *^ Osven, 'Anatomy of Yerte- ever, states that in the Gorilla the brates,' vol. iii. p. 619. hair is thinner on the back, where ** Isidore Geotfroy St.-Hilaire re- it is partly rubbed oil", than on the marks (' Hist. Nat. Generale,' torn, lower surface. ii. 1859, pp. 215-217) on the head of ^^ The ' Naturalist in Nicaragua,' man being covered with long hair; 1874, p. 209. As some confirma- also on the upper surfaces of mon- tion of Mr. Belt's view, I may quote keys and of other mammals being the following passage from Sir VV. more thickly clothed than the lower Denison (' Varieties of Vice-Kegal surfaces. This has likewise been Life,' vol. i. 1870, p. 440): " It is said observed by various authors. Prof. " to be a })ractice with the Aus- P. Gervais (' Hist. Nat. des Mam- " tralians, when the vermin get mifbres,' torn. i. 1854, p. 28), how- " troublesome, to twinge themselves." 4 58 The Descent of Man. Part I. became divested of hair for omamenial purposes, as we sliall see under Sexual Selection ; and, according to this belief, it is not surprising that man should diifer so greatly in hairiness from all other Primates, for characters, gained through sexual selection, often differ to an extraordinary degree in closely-related forms. According to a popular impression, the absence of a tail is eminently distinctive of man ; but as those apes which come nearest to him are destitute of this organ, its disapi^earance does not relate exclusively to man. The tail often differs remarkably in length within the same genus : thus in some species of Macacus it is longer than the whole body, and is formed of twenty-four vertebrre; in others it consists of a scarcely visible stumj^, containing only three or four vertebi-se. In some kinds of baboons there are twenty-five, whilst in the mandrill there are ten very small stunted caudal vertebrae, or, according to Cuvier,®° sometimes only five. The tail, whether it be long or short, almost always tapers towards the end ; and this, I presume, results from the atrophy of the terminal muscles, together with their arteries and nerves, through disuse, leading to the atrophy of the terminal bones. But no explanation can at present be given of the great diversity which often occurs in its length. Here, however, we are more specially concerned with the complete external dis- appearance of the tail. Professor Broca has recently shewn ^^ that the tail in all quadrupeds consists of two portions, generally separated abruptly from each other ; the basal portion consists of vertebras, more or less perfectly channelled and furnished with apophyses like ordinary vertebrae ; whereas those of the terminal portion are not channelled, are almost smooth, and scarcely resemble true vertebrae, A tail, though not externally visible, is really present in man and the anthropomorphous apes, and is constructed on exactly the same pattern in both. In the terminal l^ortion the vertebrae, constituting the os coccyx, are quite rudimentary, being much reduced in size and nimiber. In the basal portion, the vertebrae are likewise few, are united firmly together, and are arrested in development; but they have been rendered much broader and flatter than the corresponding vertebrae in the tails of other animals : they constitute what Broca calls the accessory sacral vertebrte. These are of functional importance by supporting certain internal parts and in other ways ; and theii' modification is directly connected with the erect ^^ Ml , St. George Mivart, ' Proc. Geoffroy, ' Hist. Xat. Gen.' torn. ii. Zoolog. Soc' 1865, pp. 562, 583. p. 244. Dr. J.E. Gray, 'Cat. Brit. Mus.: ^^ 'Revue d'Anthropologie,' 1872 ; Skeletons.' Owen, ' Anatomy of ' La Constitution des Yertebres cau- Vertebrates,' vol. ii. p. 517. Isidore dales.' Chap. II. Manner of Development. 59 or semi-erect attitude of man and the anthropomorphous apes. This conclusion is the more trustworthy, as Broca formerly held a different view, which he has now abandoned. The modifica- tion, therefore, of the basal caudal vertebrae in man and the higher apes may have been effected, directly or indirectly, through natural selection. But what arc we to say about the rudimentary and variable vertebrae of the terminal portion of the tail, forming the os coccyx ? A notion which has often been, and will no doubt again be ridiculed, namely, that friction has had something to do with the disappearance of the external portion of the tail, is not so ridiculous as it at first appears. Dr. Anderson '-"^ states that the extremely short tail of Macacus hrnnneus is formed of eleven vertebrae, including the imbedded basal ones. The extremity is tendinous and contains no vertebrae ; this is suc- ceeded by five rudimentary ones, so minute that together they are only one line and a half in length, and these are permanently bent to one side in the shape of a hook. The free part of the tail, only a little above an inch in length, includes only four more small vertebrae. This short tail is carried erect; but about a quarter of its total length is doubled on to itself to the left ; and tliis terminal part, which includes the hook-like portion, serves " to fill up the interspace between the upper divergent portion " of the callosities ;" so that the animal sits on it, and thus renders it rough and callous. Dr. Anderson thus sums up his observa- tions : " These facts seem to me to have only one explanation ; " this tail, from its short size, is in the monkey's way when it " sits down, and frequently becomes placed under the animal *' while it is in this attitude ; and from the circumstance that it " does not extend beyond the extremity of the ischial tuberosities " it seems as if the tail originally had been bent round, by the " will of the animal, into the interspace between the callosities, to " escape being pressed between them and the ground, and that " in time the curvature became permanent, fitting in of itself " when the organ happens to be sat upon." Under these circum- stances it is not surprising that the surface of the tail should liave been roughened and rendered callous; and Dr. Murie,^^ who carefully observed this species in the Zoological Gardens, as well as three other closely allied forms with slightly longer tails, says that when the animal sits down, the tail " is necessarily thrust " to one side of the buttocks ; and whether long or short its root " is consequently liable to be rubbed or chafed." As we now »2 'Proc. Zoolog. Soc.,' 1872, p. " * Proc. Zoolog. Sue. 1872, p. 210. 786. 6o The Descent of Man. Part I have evidence that mutilations occasionally produce an inherited effect/* it is not very improbable that in short-tailed monkeys, the projecting part. of the tail, being functionally useless, should after many generations have become rudimentary and distorted, from being continually rubbed and chafed. We see the projecting part in this condition in the Macacushruimeus, and. absolutely aborted in the if. ecaudatus and in several of the higher apes. Finally, then, as far as we can judge, the tail has disappeared in man and the anthropomorphous apes, owing to the terminal portion having been injured by friction during a long lapse of time ; the basal and embedded portion having been reduced and modified, so as to become suitable to the erect or semi-erect position. I have now endeavoured to shew that some of the most distinctive characters of man have in all probabiHty been acquii-ed, either directly, or more commonly indirectly, through natural selection. We should bear in mind that modifications in structure or constitution, which do not serve to adapt an organism to its habits of life, to the food which it consumes, or passively to the surrounding conditions, cannot have been thus acquired. We must not, however, be too confident in decidnig what modifications are of service to each being: we should remember ho^^ little we know about the use of many parts, or what changes in the blood or tissues may serve to fit an organism for a new climate or new kinds of food. Nor must we forget the principle of con-elation, by which, as Isidore Geoffroy has shewn in the case of man, many strange deviations of structure are tied together. Independently of correlation, a change in one part often leads, through the increased or decreased use of other parts, to other changes of a quite unexpected nature. It is also well to reflect on such facts, as the wonderful growth of galls on plants caused by the poison of an insect, and on the remarkable changes of colour in the plumage of parrots when fed on certain fishes, or inoculated with the poison of toads ;^^ for we can thus see that the fluids of the system, if altered for some special purpose, might induce other changes. We should especially bear in mind that modifications acquired 5* I allude to Dr. Brown-Sequard's inherited effects of mot-mots biting observations on the transmitted off the barbs of their own tail- effect of an operation causing epi- feathers. See jlso on the general lepsy in guinea-pigs, and likewise subject ' Variation of Animals and more recently on the analogous Plants under Domestication,' vol. effects of cutting the sympathetic ii., pp. 22-24. nerve in the neck. I shall hereafter ^^ ' The Variation of Animals and have occasion to refer to Mr. Salvin's Plants under Domestication/ vol. ii. interesting case of the apparently pp. 280, 282. CiiAi'. II. Manner of Development. 61 and continually used during past ages for some useful purpose, would probably become firmly fixed, and might be long inherited. Thus a large yet undefined extension may safely be given to the direct and indirect results of natural selection ; but I now admit, after reading the essay by NUgeli on plants, and the remarks by yarious authors with respect to animals, more especially those recently made by Professor Broca, that in the earlier editions of my * Origin of Species ' I perhaps attributed too much to the action of natural selection or the survival of the fittest. I have altered the fifth edition of the ' Origin ' so as to confine my remarks to adaptive changes of structure ; but I am convinced, from the light gained during even the last few years, that very many structures which now appear to us useless, will hereafter be proved to be useful, and will therefore come within the range of natui'al selection. Nevertheless, I did not formerly consider sufficiently the existence of structures, which, as far as we can at present judge, are neither beneficial nor injurious ; and this I believe to be one of the greatest oversights as yet detected in my work. I may be permitted to say, as some excuse, that I had two distinct objects in view; firstly, to shew that species had not been separately created, and secondly, that natural selection had been the chief agent of change, though largely aided by the inherited effects of habit, and slightly by the dii-ect action of the surrounding conditions. I was not, however, able to annul the influence of my former belief, then almost universal, that each species had been purposely created ; and this led to my tacit assumption that every detail of structure, excepting rudiments, was of some special, though unrecognised, service. Any one with this assimiption in his mind would naturally extend too far the action of natural selection, either during past or present times. Some of those who admit the principle of evolution, but reject natural selec- tion, seem to forget, when criticising my book, that I had the above two objects in view ; hence if I have erred in giving to natural selection great power, which I am very far from admitting, or in having exaggerated its power, which is in itself probable, I have at least, as I hope, done good service in aiding to overthrow the dogma of separate creations. It is, as I can now see, probable that all organic beings, including man, possess peculiarities of structure, which neither are now, nor were formerly of any service to them, and which, therefore, are of no physiological importance. Wo know not what produces the numberless slight difierenccs between the individuals of each species, for reversion only carries the problem a few steps backwards; but each peculiarity must 62 The Descent of Man. Taut I. have had its efficient cause. If these causes, whatever they may be, were to act more -uniformly and energetically during a lengthened period (and against this no reason can be assigned), the result w^ould probably be not a mere slight individual difference, but a well-marked and constant modification, though one of no physiological importance. Chauged structures, which are in no w^ay beneficial, cannot be kept uniform through natural selection, though the injurious will be thus eliminated. Uni- formity of character would, however, naturally follow from the assumed nniformity of the exciting causes, and likewise from the free intercrossing of many individuals. During successive periods, the same organism might in this manner acquire successive modifications, w^hich would be transmitted in a nearly uniform state as long as the exciting causes remained the same and there w^as free intercrossing. With respect to the exciting causes we can only say, as when speaking of so-called spon- taneous variations, that they relate much more closely to the constitution of the varying organism, than to the nature of the conditions to which it has been subjected. Conclusion.— In this chapter we have seen that as man at the present day is liable, like every other animal, to multiform individual differences or slight variations, so no doubt were the early progenitors of man ; the variations being formerly induced by the same general causes, and governed by the same general and complex laws as at present. As all animals tend to multiply beyond their means of subsistence, so it must have been with the progenitors of man; and this would inevitably lead to a struggle for existence and to natural selection. The latter process would be greatly aided by the inherited effects of the increased use of parts, and these two processes would incessantly react on each other. It appears, also, as we shall hereafter see, that various unimportant characters have been acquired by man through sexual selection. An unexplained residuum of change must be left to the assumed uniform action of those unknown agencies, which occasionally induce strongly marked and abrupt deviations of structure in our domestic productions. Judging from the habits of savages and of the greater number of the Quadrumana, primeval men, and even their ape-hke progenitors, probably lived in society. With strictly social animals, natural selection sometimes acts on the individual, through the preservation of variations which are beneficial to the community. A community which includes a large number of well-endowed individuals increases in number, and is victo- rious over other less favoured ones ; even although each separate Cjiai'. II. Manner of Devdopmcjit. 6^ member gains no advantage over the others of the same com- munity. Associated insects have thus acquired many remark- able structures^ M'hich are of little or no service to the individual, such as the pollen-collecting apparatus, or tlie sting of the worker-bee, or the great jaws of soldier-ants. With the liigher social animals, I am not aware that any structure has been modified solely for the good of the community, though some are of secondary service to it. For instance, the horns of ruminants and the great canine teeth of baboons appear to liave been acquired by the males as weapons for sexual strife, but they are used in defence of the herd or troop. In regard to certain mental powers the case, as we shall see in the fifth chapter, is wholly dificrent ; for these faculties have been chiefly, or even exclusively, gained for the benefit of the community, and the individuals thereof, have at the same time gained an advantage indirectly. It has often been objected to such views as the foregoing, that man is one of the most helpless and defenceless creatures in the uorld; and that during his early and less well-developed condition he would have been still more helpless. The Duke of Argyll, for instance, insists ^*^ that "the human frame has " diverged from the structure of brutes, in the direction of " greater physical helplessness and weakness. That is to say, it " is a divergence which of all others it is most impossible to " ascribe to mere natural selection." He adduces the naked and unprotected state of the body, the absence of great teeth or claws for defence, the small strength and speed of man, and his shght power of discovering food or of avoiding danger by smell. To these deficiencies there might be added one still more serious, namely, that he cannot climb quickly, and so escape from enemies. The loss of hair would not have been a great injury to the inhabitants of a warm country. For we know that the unclothed Fuegians can exist under a wretched climate. When we compare the defenceless state of man with that of apes, we must remember that the great canine teeth with which the latter are provided, are possessed in their full development by the males alone, and are chiefly used by them for fighting with their rivals ; yet the females, which are not thus provided, manage to survive. In regard to bodily size or strength, we do not know whether man is descended from some small species, hke the chimpanzee, or from one as powerful as the gorilla; and, therefore, we cannot say whether man has become lai-ger and stronger, or smaller »« ' Primeval Man,' 1869, p. ^ parent-form, the wolf or jackal. The Fuegians rank amongst the lowest barbarians; but I was continually struck with surprise how closely the three natives on board H.M.S. '' Beagle," who had lived some years in England, and could talk a little English, resembled us in disposition and in most of our mental faculties. If no organic being excepting man had possessed any mental power, or if his powers had been of a wholly different nature from those of the lower animals, then we should never have been able to convince ourselves that our high faculties had been gradually developed. But it can be shewn that there is no fundamental difference of this kind. We must also admit that there is a much wider interval in mental power between one of the lowest fishes, as a lamprey or lancelet, and one of the higher apes, than between an ai)e and man ; yet this interval is filled up by numberless gradations. Nor is the difference slight in moral disposition between a barbarian, such as the man described by the old navigator * See the evidence on those points, as given by Lubboclc, ' Prehistoric Times,' p. 354, &c. 66 TJie Descent of Man. Part I. Byron, -who dashed his child on the rocks for dropping a basket of sea-urchins, and a Howard or Clarkson; and in intellect, between a savage who uses hardly any abstract terms, and a Newton or Shakspeare. Differences of this kind between the highest men of the highest races and the lowest savages, are connected by the finest gradations. Therefore it is possible that they might pass and be developed into each other. My object in this chapter is to shew that there is no funda- mental difference between man and the higher mammals in their mental faculties. Each division of the subject might have been extended into a separate essay, but must here be treated briefly. As no classification of the mental i:>owers has been universally accepted, I shall arrange my remarks in the order most con- venient for my purpose ; and will select those facts which have struck me most, with the hope that they may produce some effect on the reader. With respect to animals very low in the scale, I shall give some additional facts under Sexual Selection, shewing that their mental powers are much higher than might have been expected. The variability of the faculties in the individuals of the same species is an important point for us, and some few illustrations will here be given. But it would be superfluous to enter into many details on this head, for I have found on frequent enquiry, that it is the unanimous opinion of all those who have long attended to animals of many kinds, including birds, that the individuals difibr greatly in every mental characteristic. In what manner the mental powers were first developed in the lowest organisms, is as hojoeless an enquiry as how life itself first originated. These are problems for the distant future, if they are ever to be solved by man. As man possesses the same senses as the lower animals, his fundamental intuitions must be the same. Man has also some few instincts in common, as that of self-preservation, sexual love, the love of the mother for her new-born offspring, the desire possessed by the latter to suck, and so forth. But man, perhaps, has somewhat fewer instincts than those possessed by the animals which come next to him in the series. The orang in the Eastern islands, and the chimpanzee in Africa, build plat- forms on which they sleep ; and, as both species follow the same habit, it might be argued that this was due to instinct, but we cannot feel sure that it is not the result of both animals having similar wants, and possessing similar powers of reasoning. These apes, as we may assume, avoid the many poisonous fruits of the tropics, and man has no such knowledge : but as our domestic animals, when taken to foreign lands, and when first Chap. II r. Mental Powers. 6y turned out in the spring, often eat poisonous lierbs, which they afterwards avoid, we cannot feel sure that the apes do not learn from their own experience or from that of their parents what fruits to select. It is, however, certain, as we shall presently see, that apes have an instinctive dread of serpents, and probably of other dangerous animals. The fewness and the comparative simplicity of the instincts in the higher animals are remarkable in contrast with those of the lower animals. Cuvicr maintained that instinct and intelligence stand in an inverse ratio to each other ; and some have thought that the intellectual f\iculties of the higher animals have been gradually developed from their instincts. But Pouchet, in an interesting essay,- has shewn that no such inverse ratio really exists. Those insects which possess the most wonderful instincts are certainly the most intelligent. In the vertebrate series, the least intelligent members, namely fishes and amphibians, do not possess complex instincts; and amongst mammals the animal most remarkable for its instincts, namely the beaver, is highly intelligent, as will be admitted by every one who has read Mr. Morgan's excellent work.^ Although the first dawnings of intelligence, according to jMr. Herbert Spencer,* have been developed through the multiplica- tion and co-ordination of reflex actions, and although many of the simpler instincts graduate into reflex actions, and can hardly be distinguished from them, as in the cnse of young animals sucking, yet the more complex instincts seem to have originated independently of intelligence. I am, however, very far from wishing to deny that instinctive actions may lose their fixed and untaught character, and be replaced by others performed by the aid of the free will. On the other hand, some intelligent actions, after being performed during several generations, become con- verted into instincts and are inherited, as when birds on oceanic islands learn to avoid man. These actions may then be said to be degraded in character, for they are no longer performed through reason or from experience. 13ut the greater number of the more complex instincts appear to have been gained in a wholly different manner, through the natural selection of varia- tions of simjilcr instinctive actions. Such variations ai')pear to arise from the same unknown causes acting on the cerebral organisation, which induce slight variations or individual dif- ferences in other parts of the body ; and these variations, owing ^ * L'Instinct chez les Inscctos.' ' ' The American Beaver and his ' Revue des Deux Mondes,' Feb. 1870, Works,' 1868. p. G90. ■* ' The Principles of Psychology, 2nd edit. 1870, pp. 418-443. 68 The Descent of Man. Part I. to our ignorance, are often said to arise spontaneously. We can, I think, come to no other conclusion with respect to the origin of the more complex instincts, when we reflect on the marvellous instincts of sterile worker-ants and bees, which leave no off- spring to inherit the effects of experience and of modified habits. Although, as we learn from the above-mentioned insects and the beaver, a high degree of intelligence is certainly compatible with complex instincts, and although actions, at first learnt voluntarily can soon through habit be performed with the quickness and certainty of a reflex action, yet it is not improbable that there is a certain amount of interference between the development of free intelligence and of instinct, — which latter imphes some inherited modification of the brain. Little is known about the functions of the brain, but we can perceive that as the intellectual powers become highly developed, the various parts of the brain must be connected by very intricate channels of the freest intercommunication; and as a conse- quence, each separate part would perhaps tend to be less well fitted to answer to particular sensations or associations in a definite and inherited— that is instinctive— manner. There seems even to exist some relation between a low degTce of intelligence and a strong tendency to the formation of fixed, though not inherited habits ; for as a sagacious physician remarked to me, persons who are slightly imbecile tend to act in everything by routine or habit ; and they are rendered much happier if this is en- couraged. I have thought this digression worth giving, because we may easily underrate the mental powers of the higher animals, and especially of man, when we compare their actions founded on the memory of past events, on foresight, reason, and imagination, with exactly similar actions instinctively performed by the lower animals; in this latter case the capacity of performing such actions has been gained, step by step, through the variability of the mental organs and natural selection, without any conscious inteUigenCe on the part of the animal during each successive generation. No doubt, as Mr. Wallace has argued,^ much of the intelligent work done by man is due to imitation and not to reason; but there is this great difference between his actions and many of those performed by the lower animals, namely, that man cannot, on his first trial, make, for instance, a stone hatchet or a canoe, through his power of imitation. He has to learn his work by practice ; a beaver, on the other hand, can make its dam or canal, and a bird its nest, as well, or nearly as well, and ' 'Contributions to the Theory of Natural Selection,' 1870, p. 212. Chap. III. Mental Powers. 69 a spider its wonderful web, quite as well,'' the fii-st time it tries, as when old and experienced. To return to our immediate subject : the lower animals, like man, manifestly feel pleasure and pain, happiness and misery. Haj^piness is never better exhibited than by young animals, such as i^uiDpies, kittens, lambs, &c., when playing together, like our own childi'en. Even insects play together, as has been described by that excellent observer, P. Huber,'^ who saw ants chasing and pretending to bite each other, like so many puppies. The fact that the lower animals are excited by the same emotions as ourselves is so well established, that it will not be necessary to weary the reader by many details. Terror acts in the same manner on them as on us, causing the muscles to tremble, the heart to palpitate, the sphincters to be relaxed, and the hair to stand on end. Suspicion, the offspring of fear, is eminently characteristic of most wild animals. It is, I think, impossible to read the account given by Sir E. Tennent, of the behaviour of the female elephants, used as decoys, without admitting that they intentionally practise deceit, and well know what they are about. Courage and timidity are extremely variable qualities in the individuals of the same species, as is plainly seen in our dogs. Some dogs and horses are ill-tempered, and easily turn sulky ; others are good-temi>ered ; and these qualities are certainly inherited. Every one knows how liable animals are to furious rage, and how plainly they show it. Many, and probably true, anecdotes have been published on the long-delayed and artful revenge of various animals. The accurate Eengger, and Brehm^ state that the American and African monkeys which they kept tame, certainly revenged themselves. Sir Andrew Smith, a zoologist whose scrupulous accuracy was known to many persons, told me the following story of which he was himself an eye-witness; at the Cape of Good Hope an officer had often i)lagned a certain baboon, and the animal, seeing him approaching one Sunday for parade, poured water into a hole and hastily made some thick mud, which he skilfully dashed over the officer as he passed by, to the amusement of many bystanders. For long after- wards the baboon rejoiced and triumi^hcd whenever he saw his victim. 6 For the evidence on this « All the following statements, heail, see Mr. J. Traherue Mog- given on the authority of these two gridge's most interesting work, naturalists, are taken from Rongger's 'Harvesting Ants and Trap-door 'Naturgesch. der Siingethiere von Spiders,' 1873, p. 126, 128. Paraguay,' 1830, s. 41-57, and from ^ ' Recherches sur les Mceurs dcs Brehm's 'Thierlehen,' B. i. s. 10-87. Fourmis,' 1810, p. 173. 70 The Descent of Man. Tart I. The love of a dog for his master is notorious ; as an old writer quaintly says/ " A dog is the only thing on this earth " that luvs you more than he luvs himself." In the agony of death a dog has been known to caress his master, and every one has heard of the dog suffering under vivisection, who licked the hand of the operator; this man, unless the oiDeration was fully justified by an increase of our knowledge, or unless he had a heart of stone, must have felt remorse to the last hour of his life. As WhewelP^ has well asked, " who that reads the touching " instances of maternal affection, related so often of the women of " all nations, and of the females of all animals, can doubt that the " principle of action is the same in the two cases ? " We see mater- nal affection exliibited in the most trifling details ; thus Eengger observed an American monkey (a Cebus) carefully driving away the flies which plagued her infant; and Duvaucel saw a Hylobates washing the faces of her young ones in a stream. So intense is the grief of female monkeys for the loss of their young, that it invariably caused the death of certain kinds kept under confinement by Brehm in N. Africa. Orphan monkeys were always adopted and carefully guarded by the other monkeys, both males and females. One female baboon had so capacious a heart that she not only adopted young monkeys of other species, but stole young dogs and cats, which she continually carried about. Her kindness, however, did not go so far as to share her food with her adopted offspring, at which Brehm was surprised, as his monkeys always divided everythiDg quite fairly with their own young ones. An adopted kitten scratched this affectionate baboon, who certainly had a fine intellect, for she was much astonished at being scratched, and immediately examined the kitten's feet, and without more ado bit off the claws.^^ In the Zoological Gardens, I heard from the keeper that an old baboon (C, chacmci) had adopted a Ehesus monkey; but when a young drill and mandrill were placed in the cage, she seemed to perceive that these monkeys, though distinct species, were her nearer relatives, for she at once rejected the Ehesus and adopted both of them. The young Ehesus, as I saw, was greatly discontented at being thus rejected, and it would, like a naughty child, annoy and attack the young drill and mandrill 3 Quoted by Dr. Lauder Lindsay, 72), disputes the possibility of this. u his ' Physiology of Mind in the act as described by Brehm, for the Lower Animals ;' ' Journal of Mental sake of discrediting my work. Science,' April 1871, p. 38. Therefore I tried, and found that I 10 ' BridiT-ewater Treatise,' p. 263. could readily seize with my own ^1 A critic, without any grounds teeth the sharp little claws of a ('Quarterly Review,' July 1871, p. kitten nearly five weeks old. CuAP. III. Mental Powers, yi whenever it could do so with safety ; this conduct exciting great indignation in the old baboon. Monkeys will also, according to Brehm, defend their master when attacked by any one, as well as dogs to whom they are attached, from the attacks of other dogs. But we here trench on the subjects of sympathy and fidelity, to which I shall recur. Some of Brehm's monkeys took much delight in teasing a certain old dog whom they disliked, as well as other animals, in various ingenious ways. Most of ihe more complex emotions arc common to the higher animals and ourselves. Every one has seen how jealous a dog is of his master's affection, if lavished on any other creature ; and I have observed the same fact with monkeys. Tliis shews that animals not only love, but have desire to bo loved. Animals manifestly feel emulation. They love ajipro- bation or praise ; and a dog carrying a basket for his master exhibits in a high degree self-complacency or pride. There can, I think, be no doubt that a dog feels shame, as distinct from fear, and something very like modesty when begging too often for food. A great dog scorns the snarling of a httle dog, and this may be called magnanimity. Several observers have stated that monkeys certainly dislike being laughed at ; and they sometimes invent imaginary offences. In the Zoological Gardens I saw a baboon who always got into a furious rage v/hen his keeper took out a letter or book and read it aloud to him ; and his rage was so violent that, as I witnessed on one occasion, he bit his own leg till the blood flowed. Dogs show what may be fairly called a sense of humour, as distinct from mere jilay ; if a bit of stick or other such object be thrown to one, he will often carry it away for a short distance ; and then squatting down with it on the ground close before him, will wait until his master comes quite close to take it away. The dog will then seize it and rush away in triumph, repeating the same manoeuvre, and evidently enjoying the practical joke. Wo will now turn to the more intellectual emotions and faculties, which are very important, as forming the basis for the development of the higher mental powers. Animals manifestly enjoy excitement, and suffer from ennui, as may be seen with dogs, and, according to Eengger, with monkeys. All animals feel Wonder, and many exhibit Curiositij. They sometimes suffer from this latter quality, as when the hunter plays antics and thus attracts them ; I have witnessed this with doer, and so it is with the wary chamois, and with some kinds of wild-ducks. Brehm gives a curious account of the instinctive dread, which his monkeys exhibited, for snakes; but their curiosity was so great that they could not desist from occasionally satiating 72 The Descent of Man. Part I. their horror in a most human fashion, by lifting up the lid of the box in which the snakes were kept. I was so much surprised at his account, that I took a stuffed and coiled-up snake into the monkey-house at the Zoological Gardens, and the excitement thus caused was one of the most curious spectacles which I ever beheld. Three species of Cercopithecus were the most alarmed ; they dashed about their cages, and uttered sharp signal cries of danger, which were understood by the other monkeys. A few young monkeys and one old Anubis baboon alone took no notice of the snake. I then placed the stuffed specimen on the ground in one of the larger comx)artments. After a time all the monkeys collected round it in a large ch'cle, and staring intently, presented a most ludicrous appearance. They became extremely nervous ; so that when a wooden ball, with which they were familiar as a plaything, was accidentally moved in the straw, under which it was partly hidden, they all instantly started away. These monkeys behaved very differently when a dead fish, a mouse,^^ a living turtle, and other new objects were placed in their cages; for though at fkst frightened, they soon approached, handled and examined them. I then placed a live snake in a paper bag, with the mouth loosely closed, in one of the larger compartments. One of the monkeys immediately approached, cautiously opened the bag a little, peeped in, and instantly dashed away. Then I witnessed what Brehm has described, for monkey after monkey, with head raised high and turned on one side, could not resist taking a momentary peep into the upright bag, at the dreadful object lying quietly at the bottom. It would almost appear as if monkeys had some notion of zoological affinities, for those kept by Brehm exhibited a strange, though mistaken, instinctive di-ead of innocent lizards and frogs.. An orang, also, has been known to be much alarmed at the first sight of a turtle.^^ The principle of Imitation is strong in man, and especially, as I have myself observed, with savages. In certain morbid states of the brain this tendency is exaggerated to an extraordinary degree ; some hemiplegic patients and others, at the commence- ment of inflammatory softening of the brain, unconsciously imitate every word which is uttered, whether in their own or in a foreign language, and every gesture or action which is per- formed near them.-* Desor^^ has remarked that no animal ^2 I have given a short account of Mammalia,' 1841, p. 405. of their behaviour on this occasion '* Dr. Bateman ' On Aphasia,' in my 'Expression of the Emotions,' 1870, p. 110. p. 43. *' Quoted by Vogt, 'Me'moire sur »3 \V. C. L. Martin, 'Nat. Hist, les Microcephales,' 1867, p. 168. CiL^.p. III. Mental Powers. 73 volunt ' ThiorlcdxMi,' P.. i. s. 79, 82. 82 The Descent of Man. Tart I. actually closed for a time against the caravan. It deserves notice that these baboons thus acted in concert. Mr. Wallace*^ on three occasions saw female orangs, accompanied by their young, " breaking off branches and the great spiny fruit of the " Durian tree, with every appearance of rage; causing such a " shower of missiles as effectually kept us from approaching too " near the tree." As I have repeatedly seen, a chimpanzee will throw any object at hand at a person who offends him ; and the before mentioned baboon at the Cape of Good Hope prepared mud for the purpose. In the Zoological Gardens, a monkey, which had weak teeth, used to break open nuts with a stone ; and I was assui'ed by the keepers that after using the stone, he hid it in the straw, and would not let any other monkey touch it. Here, then, we have the idea of property ; but this idea is common to every dog with a bone, and to most or all birds with their nests. The Duke of Argyll'*- remarks, that the fashioning of an implement for a special purpose is absolutely peculiar to man ; and he considers that this forms an immeasiu'able gulf between him and the brutes. This is no doubt a very important dis- tinction ; but there appears to me much truth in Sir J. Lubbock's suggestion,'^ that when primeval man first used flint-stones for any purpose, he would have accidentally splintered them, and would then have used the sharp fragments. From this step it would be a small one to break the tlints on purpose, and not a very wide step to fashion them rudely. This latter advance, however, may have taken long ages, if we may judge by the immense interval of time which elai^sed before the men of the neolithic period took to grinding and polishing their stone tools. In breaking the flints, as Sir J. Lubbock likewise remarks, sparks would have been emitted, and in grinding them heat would have been evolved: thus the two usual methods of " obtaining fire may have originated." The nature of fire would have been known in the many volcanic regions where lava occasionally flows through forests. The anthropomoriihous apes, guided probably by instinct, build for themselves tem- porary platforms ; but as many instincts are largely controlled by Teason, the simpler ones, such as this of buildiog a platform, might readily pass into a voluntary and conscious act. The orang is known to cover itself at night with the leaves of the Pandanus ; and Brehm states that one of his baboons used to protect itself from the heat of the sun by throwing a straw-mat 41 'The Malay Archipelago,' vol. 14-5,147. 1. -1869. p. 87. ■'^ ' Trehistoric Times,' 1865, p. « ' Primeval Mau,' 1869, pp. 473, &c Chap. II r. Mental Powers. %i over its head. In tliese several habits, we probably see the first steps towards some of the simpler arts, such as rude architecture and dress, as they arose amongst the early progenitors of man. Abstraction, General Conceptions, ^elf -consciousness, Mtntd Individuality.— It would be very difficult for any one with even much more knowledge than I possess, to determine how far animals exhibit any traces of these high mental powers. This difficulty arises from the impossibility of judging what passes through the mind of an animal ; and again, the fact that writers differ to a great extent in the meaning which they attribute to the above terms, causes a further difficulty. If one may judge from various articles wliich have been published lately, the greatest stress seems to be laid on the supposed entire absence in animals of the power of abstraction, or of forming general concepts. But when a dog sees another dog at a distance, it is often clear that he perceives that it is a dog in the abstract ; for when he gets nearer his whole manner suddenly changes, if the other dog be a friend. A recent writer remarks, that in all such cases it is a pure assumption to assert that the mental act is not essentially of the same nature in the animal as in man. If either refers what he perceives with his senses to a mental concept, then so do both.*^ When I say to my terrier, in an eager voice (and I have made the trial many times), " Hi, hi, where is it ? " she at once takes it as a sign that something is to be hunted, and generally first looks quickly all around, and then rushes into the nearest thicket, to scent for any game, but finding nothing, she looks up into any neighbouring tree for a squirrel. Now do not these actions clearly shew that she had in lier mind a general idea or concept that some animal is to bo discovered and hunted ? It may be freely admitted that no animal is self-conscious, if by this term it is implied, that he reflects on such points, as whence he comes or whither he will go, or what is life and deatli, and so forth. But how can we feel sure that an old dog with an excellent memory and some power of imagination, as shewn by his dreams, never reflects on his past pleasures or pains in the chase ? And this would be a form of self-consciousness. On tlie other hand, as Buchner^^ has remarked, how little can the hard- worked wife of a degraded Australian savage, who uses very few abstract words, and cannot count above four, exert her self- consciousness, or reflect on the nature of her own existence. It is generally admitted, that the higher animals possess memory, ** ^Ir. Hookham, in a lettei- to *^ 'Conferences sui- la Tli(^orie Prof. Max Miiller, in the ' Biimiug- Darwinienne,' French translat. ham News,' May 1873. 18f;9, p. 1:52. 84 The Descent of Man. Past I. attention, association, and even some imagination and reason. If these powers, which differ much in different animals, are capable of improvement, there seems no great improbability in more comj^lex faculties, such as the higher forms of abstraction, and self-consciousness, &c., having been evolved through the development and combination of the simpler ones. It has been urged against the views here maintained, that it is impossible to say at what point in the ascending scale animals become capable of abstraction, &c. ; but who can say at what age this occurs in our young children ? We see at least that such powers are developed in children by imperceptible degrees. That animals retain their mental individuality is unquestion- able. When my voice awakened a train of old associations in the mind of the before-mentioned dog, he must have retained his mental individuality, although every atom of his brain had probably undergone change more than once during the interval of five years. This dog might have brought forward the argument lately advanced to crush all evolutionists, and said, " I abide amid all mental moods and all material changes. . . . " The teaching that atoms leave their impressions as legacies to '' other atoms falling into the places they have vacated is con- " tradictory of the utterance of consciousness, and is therefore '' false ; but it is the teaching necessitated by evolutionism, con- '' sequently the hypothesis is a false one."'^*^ Language. — This faculty has justly been considered as one of the chief distinctions between man and the lower animals. But man, as a highly competent judge, Archbishop Whately remarks, " is not the only animal that can make use of language to express " what is passing in his mind, and can understand, more or less, "what is so expressed by another."^' In Paraguay the Cebus, azaroi when excited utters at least six distinct sounds, which excite in other monkeys similar emotions."^^ The movements of the features and gestures of monkeys are understood by us, and they joartly understand ours, as Pengger and others declare. It is a more remarkable fact that the dog, since being domesticated, has learnt to bark^^ in at least four or five distinct tones. Although barking is a new art, no doubt the wild parent-species of the dog expressed their feelings by cries of various kinds. "With the domesticated dog we have the bark of eagerness, as in the chase ; that of anger, as well as growling ; the yelp or howl of despair, as when shut up ; the baying at night ; the bark of joy, as *^ The Rev. Dr. J. M'Canu, ' Auti- "^ Rengger, ibid. s. 45. Darwinism,' 1869, p. 13. ^^ See mj 'Variation of Ani- *'' Quoted in 'Anthropological Re- mak- and Plants under Domestica- view ' 18.'34, p. 158. tion,' vol. i. p. 27. Ch ap. III. Mental Powers. 8 5 when starting on a walk with his master ; and the very distinct one of demand or snppheation, as when wishing for a door or window to be opened. According to Houzean, who paid par- ticular attention to the subject, the domestic fowl utters at least a dozen significant sounds.^*^ The habitual use of articulate language is, however, iieculiar to man ; but he uses, in common with the lower animals, inarti- culate cries to express his meaning, aided by gestures and the movements of the muscles of the face/'^ This especially holds good with the more simple and vivid feelings, which are but little connected with our higher intelligence. Our cries of pain, fear, surprise, anger, together with tlieir appropriate actionS; and the murmur of a mother to her beloved child, are more expressive than any words. That which distinguishes man from the lower animals is not the understanding of articulate sounds, for, as every one knows, dogs understand many words and sentences. In this respect they are at the same stage of development as infants, between the ages of ten and twelve months, who understand many words and short sentences, but cannot yet utter a single word. It is not the mere articulation which is our distinguishing character, for parrots and other birds possess this power. Nor is it the mere capacity of con- necting definite sounds with definite ideas ; for it is certain that some parrots, which have been taught to speak, connect un- erringly words with things, and persons with events.^^ The lower animals differ from man solely in his almost infinitely larger power of associating together the most diversified *• 'Facultes Meutales des Ani- to add to the "good morning" a maux,' torn. ii. 1872, p. 346-349. short sentence, which was nevcM- ^^ See a discussion on this subject once repeated after his father's in Mr. E. B. Tylor's very interesting death. He scolded violently a work, ' Researches into the Early strange dog which came into the History of Mankind,' 18(35, chaps. room through the open window; ii. to iv. and he scolded another parrot (say- " I have received several detailed ing "you naughty polly ") which accounts to this effect. Admiral had got out of its cage, and was Sir J. Sulivan, whom I know to be eating apples on the kitchen table, a careful observer, assures me that See also, to the same elfect, Houzeau an African parrot, long kept in his on parrots, ' Facultes Mentales,' lather's house, invariably called torn, ii, p. 309. Dr. A. Moschkau certain persons of the household, as informs me that he knew a starling well as visitors, by their names. He which never made a mistake in said "good morning" to every one at saying in German " good morning " breakfast, and "good night " to each to persons arriving, and " good- as they left the room at night, and bye, old follow," to those departing, never reversed these salutations. I could add several other such To Sir J. Sulivan's father, he used cases. 86 TJie Descent of Man. Paet L sounds and ideas; and this obviously depends on the high development of his mental powers. As Home Took, one of the founders of the noble science of philology, observes, language is an art, like brewing or baking ; but writing would have been a better simile. It certainly is not a true instinct, for every language has to be learnt. It differs, however, widely from all ordinary arts, for man has an in- stinctive tendency to speak, as we see in the babble of our young children ; whilst no child has an instinctive tendency to brew, bake, or write. Moreover, no philologist now supposes that any language has been deliberately invented ; it has been slowly and unconsciously developed by many steps.^^ The sounds uttered by birds offer in several respects the nearest analogy to language, for all the members of the same species utter the same instinctive cries expressive of their emotions ; and all the kinds which sing, exert their power instinctively; but the actual song, and even the call notes, are learnt from their parents or foster-imrcnts. These sounds, as Daines Barrington^* has proved, " are no more innate than language is in man." The first attempts to sing " may be compared to the imperfect " endeavour in a child to babble." The young males continue practising, or as the bird-catchers say, " recording," for ten or eleven months. Their first essays show hardly a rudiment of the future song ; but as they grow older we can perceive what they are aiming at ; and at last they are said " to sing their " song round." Nestlings which have learnt the song of a distinct species, as with the canary-birds educated in the Tyrol, teach and transmit their new song to their offspring. The slight natural differences of song in the same species inhabiting different districts may be appositely compared, as Barrington remarks, " to provincial dialects ;" and the songs of allied, though distinct species may be compared with the languages of distinct races of man. I have given the foregoing details to shew that an instinctive tendency to acquire an art is not peculiar to man. With respect to the origin of articulate language, after having read on the one side the highly interesting works of Mr. Hens- ^^ See some good remarks on this " gards the immediate end to be head by Prof. Whitney, in his " attained ; unconsciously as regards ' Oriental and Linguistic Studies,' " the further consequences of the 1873, p. 354. He observes that the " act." desire of communication between ^^ Hon. Daines Barrington in man is the living force, which, ' Philosoph. Transactions,' 1773, p. in the development of language, 262. See also Dureau de la Malle, " works both consciously and un- in * Ann. des. Sc. Nat.* 3rd series, " consciously; consciously as re- Zoolog. torn. x. p. 119. Chap. 111. Mental Poivers. 87 leigh Wedgwood, the Eev. F. Farrar, and Prof. Schleicher,^^ and the celebrated lectures of Prof. Max Mtiller on the other side, I cannot doubt that language owes its origin to the imitation and modification of various natural sounds, the voices of other animals, and man's own instinctive cries, aided by signs and gestures. AVhen we treat of sexual selection we shall sec that primeval man, or rather some early progenitor of man, probably first used his voice in producing true musical cadences, that is in singing, as do some of the gibbon-apes at the present day ; and we may conclude from a widely-spread analogy, that this power would have been especially exerted during the courtship of the sexes, — would have expressed various emotions, such as love, jealousy, triumph, — and would have served as a challenge to rivals. It is, therefore, probable that the imitation of musical cries by articulate sounds may have given rise to words expres- sive of various complex emotions. The strong tendency in our nearest allies, the monkeys, in microcephalous idiots,"^'^ and in the barbarous races of mankind, to imitate whatever they hear deserves notice, as bearing on the subject of imitation. Since monkeys certainly understand much that is said to them by man, and when wild, utter signal-cries of danger to their fellows ; ^^ and since fowls give distinct warnings for danger on the gi-ound, or in the sky from hawks (both, as well as a third cry, intelligible to dogs),^*^ may not some unusually wise ape-like animal have imitated the growl of a beast of prey, and thus told his fellow-monkeys the nature of the expected danger ? This would have been a first step in the formation of a language. As the voice was used more and more, the vocal organs would have been strengthened and perfected through the principle of the inherited effects of use ; and this would have reacted on the power of speech. But the relation between the continued use of language and the development of the brain, has no doubt been far more important. The mental powers in some early pro- genitor of man must have been more highly developed than in " <0n the Origin of Language,' ^e y^g^^ * Memoire sur les Micro- by H. Wedgwood, 18GG. 'Chapters cephales,' 1867, p. 1(39. With re- on Language,' by the Rev. F. W. spect to savages, I have given some Farrar, 1865. These works are facts in my ' Jouru.il of llesearches,' most interesting. See also ' De la &c., 1845/p. 206. Phys. et de i'arole,' par Albert ^7 g^g ^.\^,.^y^. evidence on this head Lemoine, 1865, p. 190. The work in the two works so often quoted, on this subject, by the Lite Prot". by Brehm and Ilunggei-. Aug. Schleicher, has been translated ^^ Houzeau gives a very curious by Dr. Bikkers into English, under account of his oljservations on *liis the title of ' Darwinism tested by subject in liis ' Facultes Meutales the Science of Language,' 1869 dcs Aniniaux,' toni. ii., p. 348. 88 The Descent of Man. Part I. any existing ape, before even the most imperfect form of speech could have come into use ; but we may confidently believe that the continued use and advancement of this power Avould have reacted on the mind itself, by enabling and encouraging it to carry on long trains of thought. A complex train of thought can no more be carried on without the aid of words, whether spoken or silent, than a long calculation without the use of figures or algebra. It ajopears, also, that even an ordinary train of thought almost requires, or is greatly facilitated by some form of language, for the dumb, deaf, and blind girl, Laura Bridgman, was observed to use her fingers whilst dreaming.^^ Nevertheless, a long succession of vivid and connected ideas may pass through the mind without the aid of any form of language, as we may infer from the movements of dogs during their dreams. We have, also, seen that animals are able to reason to a certain extent, manifestly without the aid of language. The intimate connection between the brain, as it is now developed in us, and the faculty of speech, is well shewn by those curious cases of brain-disease in which speech is specially affected, as when the power to remember substantives is lost, whilst other words can be correctly used, or where substantives of a certain class, or all except the initial letters of substantives and i^roper names are forgotten.^ There is no more improb- ability in the continued use of the mental and vocal organs leading to inherited changes in their structure and functions, than in the case of handwriting, which depends partly on the form of the hand and partly on the disposition of the mind ; and hand- writing is certainly inherited.''^ Several writers, more especially Prof. Max Muller,^^ have lately insisted that the use of language implies the power of forming general concepts ; and that as no animals are supposed to possess this power, an impossible barrier is formed between them and man.*^^ With respect to animals, I have already 53 See remarks on tins head by ^- Lectures on 'Mr. Darwin's Phi- Dr. Maudsley, 'The Physiology and losophy of Language,' 1873. Pathology of Mind,' 2ud edit. 1868, ^'^ The judgment of a distin- p. 199. guished philologist, such as Prof. ^^ Many curious cases have been Whitney, will have far more weight recorded. See, for instance, Dr. on this point than anything that Bateman 'On Aphasia,' 1870, p. 27, I can say. He remarks ('Oriental 31, 53, 100, &c. Also, 'Inquiries and Linguistic Studies,' 1873, p.. Concei-ning the Intellectual Powers,' 297), in speaking of Bleek's views : by Dr. Abercrombie, 1838, p. 150. "Because on the grand scale lan- ^^ 'The Variation of Animals " guage is the necessary auxiliary and Plants under Domestication,' " of thought, indispensable to tlie vol. ii. p. 6. " development of the power of Chap. II r. Mental Pozvc7'S, 89 endeavoured to show that they have this power, at least in a riule and incipient degree. As for as concerns infants of from ten to eleven months old, and deaf-mutes, it seems to mo in- credible, that they should be able to connect certain sounds with certain general ideas as quickly as they do, unless such ideas were already formed in their minds. The same remark may be extended to the more intelligent animals ; as Mr. Leslie Stephen observes,'^'* " A dog frames a general concept of cats or sheep, " and knows the corresponding words as well as a philosopher. " And the capacity to understand is as good a j^roof of vocal " intelligence, though in an inferior degree, as the capacity to " speak> Why the organs now used for speech should have been originally perfected for this purpose, rather than any other organs, it is not difficult to see. Ants have considerable powers of intercommunication by means of their antennjc, as shewn by Huber, who devotes a whole chapter to their language. We might have used our fingers as efficient instruments, for a person with practice can report to a deaf man every word of a speech rapidly delivered at a public meeting; but the loss of our hands, whilst thus employed, would have been a serious inconvenience. As all the higher mammals possess vocal organs, constructed on the same general plan as ours, and used as a means of communication, it was obviously probable that these same organs would be still further developed if the power of communication had to be improved ; and this has been cftected by the aid of adjoining and well adapted parts, namely the tongue and lips.^5 The fact of the higher apes not using their vocal organs for speech, no doubt depends on their intelligence not having been sufficiently advanced. The possession by them of " thinking, to the distinctness and " fingers into imitation of spoken " variety and complexity of cogni- " words." Jlax Miillcr gives in " tions to the full mastery of con- italics ('Lectures on ]\Jr. Darwin's '• sciousness ; therefore he woukl Philosophy of Language,' 187.'>, " fain make thought absolutely im- third lecture) the following aphor- " possible without speech, identify- ism: "There is no thought with- " ing the faculty with its instru- " out words, as little as tiiere are " ment. He might just as reason- " words without thought." What " ably assert that the liuman hand a strange definition must here be " cannot act without a tool. With gi\-cn to the word thought ! " such a doctrine to start from, he ^^ ' Essays on Free-thinking,' tS;c., " cannot stop short of IMiiiler's 1873, p. 82. " worst paradoxes, that an infant ^^ See some ggod remarks to this " (m /«»5, not speaking) is not a effect by Dr. Maudslcy, ' The I'hy- •* human being, and that deaf-mutes siology and Pathology of Mind,' " do not become possessed of reason 18G8, p. l'J9. " until tliey learn to twist their 90 ' The Descent of Man. Part 1. organs, wliicli with long- continued practice might have been used for speech, although not thus used, is paralleled by the case of many birds which possess organs fitted for singing, though they never sing. Thus, the nightingale and crow have vocal organs similarly constructed, these being used by the former for diversified song, and by the latter only for croaking.*^' If it be asked why apes have not had their intellects developed to the same degree as that of man, general causes only can be assigned in answer, and it is unreasonable to expect anything more definite, considering our ignorance with respect to the successive stages of development through which each creature has passed. • The formation of different languages and of distinct species, and the proofs that both have been developed through a gradual process, are curiously parallel.^^ But we can trace the formation of many words further back than that of species, for we can perceive how they actually arose from the imitation of various sounds. We find in distinct languages striking homologies duo to community of descent, and analogies due to a similar process of formation. The manner in which certain letters or sounds change when others change is very like correlated growth. We have in both cases the reduplication of parts, the effects of long- continued use, and so forth. The frequent presence of rudi- ments, both in languages and in species, is still more remarkable. The letter m in the word am, means / ; so that in the expres- sion / am, a superfluous and useless rudiment has been retained. In the spelling also of words, letters often remain as the rudi- ments of ancient forms of pronunciation. Languages, like organic beings, can be classed in groups under groups ; and they can be classed either naturally according to descent, or arti- ficially by other characters. Dominant languages and dialects spread widely, and lead to the gradual extinction of other^ tongues. A language, like a species, when once extinct, never, as Sir C. Lyell remarks, reappears. The same language never has two birth-places. Distinct languages may be crossed or blended together.''^ We see variability in every tongue, and new ^^ Macgillivray, ' Hist, of British display any -anusual capacity for Birds,' A'ol. ii. 1839, p. 29. An imitation. ' Researches in Zoology,' excellent observer, Mr. Blackwall, 1834, p. 158. remarks that the magpie learns to ''^ See the very interesting pa- pronounce single words, and even rallelism between the development short sentences, more readily than of species and languages, given by almost any other British bird ; yet, Sir C. Lyell in ' The Geolog. Evi- as he adds, after long and closely dences of the Antiquity of Man,' investigating its habits, he has 1863, chap, xxiii. Lever known it, in a state of nature, ^^ See remarks to this effect by CiLvp. III. Mental Powers, • 91 words are continually cropping np ; but as there is a limit to the powers of the memory, single words, like whole languages, gradually become extinct. As Max Miiller'^^ has well re- marked : — ''' A struggle for life is constantly going on amongst *Hhe words and grammatical forms in each language. The " better, the shorter, the easier forms are constantly gaining the " upper hand, and they owe their success to their own inherent " virtue." To these more important causes of the survival of certain words, mere novelty and fashion may be added ; for there is in the mind of man a strong love for slight changes in all things. The survival or preservation of certain favoured words in the struggle for existence is natural selection. The perfectly regular and wonderfully complex construction of the languages of many barbarous nations has often been advanced as a proof, either of the divine origin of these lan- guages, or of the high art and former civilisation of their founders. Thus F. von Schlegel writes : " In those languages " which appear to be at the lowest grade of intellectual culture, *' we frequently observe a very high and elaborate degree of art "in their gi-ammatical structure. This is especially the case " with the Basque and the Lapponian, and many of the Ame- " rican languages.'"''® But it is assuredly an error to speak of any language as an art, in the sense of its having been elabor- ately and methodically formed. Philologists now admit that conjugations, declensions, &c., originally existed as distinct words, since joined together; and as such words express the most obvious relations between objects and persons, it is not surprising that they should have been used by the men of most races during the earliest ages. With respect to perfection, the following illustration will best shew how easily we may err : a Crinoid sometimes consists of no less than 150,000 pieces of shell,'^ all arranged with i^erfect symmetry in radiating lines ; but a naturalist does not consider an animal of tliis kind as more perfect than a bilateral one with comparatively few jDarts, and with none of these parts alike, excepting on the opposite sides of the body. He justly considers the differentiation and special- isation of organs as the test of perfection. So with languages ; the most symmetrical and complex ought not to be ranked above irregular, abbreviated, and bastardised languages, which have the Rev. F. W. Fanar, in an in- '« Quoted by C. S. Wake, ' Cliap- terostiiig article, eutitleJ ' Philo- ters on Mau,' 1868, p. 101, logy and Darwinism' in 'Nature,' '' Buckland, 'Bridgewatcr Trca- March 2-tth, 1870, p. 528. ti.se.' p. 411. «3 ' Nature,' Jan. tith, 1870, p. 2:)7. 92 The Descent of Man. Part I. borrowed expressive words and useful forms of construction from various conquering, conquered, or immigrant races. From these few and imperfect remarlis I conclude tliat the extremely complex and regular construction of many barbarous languages, is no proof that they owe their origin to a special act of creation.'^^ Nor, as we have seen, does the faculty of articulate speech in itself offer any insuperable objection to the belief that man has been developed from some lower form. Bense of Beauty. — This sense has been declared to be peculiar to man. I refer here only to the pleasure given by certain colours, forms, and sounds, and which may fairly be called a sense of the beautiful ; with cultivated men such sensations arc, however, intimately associated with complex ideas and trains of thought. When we behold a male bird elaborately displaying his graceful plumes or splendid colours , before the female, whilst other birds, not thus decorated, make no such display, it is impossible to doubt that she admires the beauty of her male partner. As women everywhere deck themselves with these plumes, the beauty of such ornaments cannot be disputed. As we shall see later, the nests of humming-birds, and the playing passages of bower-birds are tastefully ornamented with gaily-coloured objects; and this shews that they must receive some kind of pleasure from the sight of such things. With the great majority of animals, however, the taste for the beautiful is confined, as far as we can judge, to the attractions of the opposite sex. The sweet strains poured forth by many male birds during the season of love, are certainly admired by the females, of which fact evidence will hereafter be given. If female birds had been incapable of appreciating the beautiful colours, the ornaments, and voices of their male partners, all the labour and anxiety exhibited by the latter in disi^laying their charms before the females would have been thrown away ; and this it is impossible to admit. Why certain bright .colours should excite pleasure cannot, I presume, be explained, any more than why certain flavours and scents are agreeable ; but habit has something to do with the result, for that which is at first unpleasant to our senses,' ultimately becomes pleasant, and habits are inherited. With respect to sounds, Helmholtz has explained to a certain extent on physiological principles, why harmonies and certain cadences are agreeable. But besides this, sounds frequently recurring at irregular intervals are ''- Soe some gooil remarks on the J. Lubbock, 'Origin of Civilisatiou,* simplification of languages^ by Sir 1870, p. 278. CuAp. 111. Mental Powers, 93 highly disagreeable, as every one will admit who has listened at night to the irregular flapping of a rope on board ship. The same princii^le seems to come into play with vision, as the eye prefers symmetry or figures with some regular recurrence. Patterns of this kind are employed by even the lowest savages as ornaments; and they have been developed through sexual selection for the adornment of some male animals. Whether we can or not give any reason for the pleasure thus derived from vision and hearing, yet man and many of the lower animals are alike pleased by the same colours, graceful shading and forms, and the same sounds. The taste for the beautiful, at least as far as female beauty is concerned, is not of a special nature in the human mind ; for it differs widely in the different races of man, and is not quite the same even in the different nations of the same race. Judging from the hideous ornaments, and the equally hideous music admired by most savages, it might be urged that their jesthetic faculty was not so highly developed as in certain animals, for instance, as in birds. Obviously no animal would be capable of admiring such scenes as the heavens at night, a beautiful land- scape, or refined music; but such high tastes are acquired through culture, and depend on complex associations ; they are not enjoyed by barbarians or by uneducated persons. Many of the faculties, which have been of inestimable service to man for his progressive advancement, such as the powers of the imagination, wonder, curiosity, an undefined sense of beauty, a tendency to imitation, and the love of excitement or novelty, could hardly fail to lead to capricious changes of customs and fashions. I have alluded to this point, because a recent writer '^ has oddly fixed on Caprice " as one of the most remarkable and "typical differences between savages and brutes." But not only can we partially understand how it is that man is from various conflicting influences rendered capricious, but that the lower animals are, as we shall hereafter see, likewise capri- cious in their affections, aversions, and sense of beauty. There is also reason to suspect that they love novelty, for it own sake. Bdief in God — BeJiyirm. — There is no evidence that man was aboriginally endowed with the ennobling belief in the existence of an Omnipotent God. On the contrary there is ample evidence, derived not from hasty travellers, but from men who have long resided with savages, that numerous races have existed, and still exist, who have no idea of one or more gods, and who have no " 'The Spectator,' Dec. -tth, 1SG9, p. 1430. 94 The Descent of Man. Part I. words in their languages to express snch an idea/* The question is of course wholly distinct from that higher one, whether there exists a Creator and Euler of the universe ; and this has been answered in the affirmative by some of the highest intellects that have ever existed. If, however, we include under the term " religion '' the belief in miseen or spiritual agencies, the case is wholly different ; for this belief seems to be universal with the less civilised races. Nor is it difficult to comprehend how it arose. As soon as the important faculties of the imagination, wonder, and curiosity, together with some power of reasoning, had become partially developed, man would naturally crave to understand what was passing around him, and would have vaguely speculated on his own existence. As Mr. M'Lennan'^ has remarked, " Some explan- " ation of the phenomena of life, a man must feign for himself; " and to judge from the universality of it, the simplest hypothesis, " and the first to occur to men, seems to have been that natural " phenomena are ascribable to the presence in animals, plants, " and things, and in the forces of nature, of such spirits prompting " to action as men are conscious they themselves possess." It is also probable, as Mr. Tylor has shewn, that dreams may have first given rise to the notion of spirits ; for savages do not readily distinguish between subjective and objective impressions. When •a savage dreams, the figures which appear before him arc believed to have come from a distance, and to stand over him ; or " the soul of the dreamer goes out on its travels, and comes " home with a remembrance of what it has seen."^^" But until ^■* See an excellent article on this forms of religious belief throughout subject by the Re\^. F. W. Farrar, the world, by man being led through in the 'Anthropological Review,' dreams, shadows, and other causes, Aug. 1864, p. ccxvii. For further to look at himself as a double facts see Sir J. Lubbock, ' Pre- essence, corporeal and spiritual. As historic Times,' 2nd edit. 1869, p. the spiritual being is supposed to .564 ; and especially the chapters on exist after death and to be power- Religion in his 'Origin of Civilisa- ful, it is propitiated by various gifts tion,' 1870. and ceremonies, and its aid involved. "''" ' The Worship of Animals and He then further shews that names Plants,' in the ' Fortnightly Review,' or nicknames given from some Oct. 1, 1869, p. 422. animal or other object, to the early "^ Tylor, ' Early History of Man- progenitors or founders of a tribe, kind,' 1865, p. 6. See also the arc supposed after a long interval three striking chapters on the De- to represent the real progenitor of velopment of Religion, in Lubbock's the tribe; and such animal or object ' Origin of Civilisation,' 1870. In a is then naturally believed still to like manner Mr, Herbert Spencer, exist as a spirit, is held sacred, and in his ingenious essay in the ' Fort- worshipped as a god. Nevertheless nightly Review' (May 1st, 1870, I cannot but suspect that there is p. 535), accounts for the earliest a still earlier and ruder stage, when Chap. II f. Mental Powers, 95 the faculties of imagination, curiosity, reason, &c., had been fairly well developed in the mind of man, his dreams would not have led him to believe in s^Dirits, any more than in the case of a dog. The tendency in savages to imagine that natural objects and agencies are animated by spiritual or living essences, is perha]')s illustrated by a little fact which I once noticed : my dog, a full- grown and very sensible animal, was lying on the lawn during a liot and still day ; but at a little distance a slight breeze occa- sionally moved an open parasol, which would have been wholly disregarded by the dog, had any one stood near it. As it was, every time that the parasol slightly moved, the dog growled fiercely and barked. He must, I think, have reasoned to himself in a rapid and unconscious manner, that movement without any' apparent cause indicated the presence of some strange living agent, and that no stranger had a right to be on his territory. The belief in spiritual agencies would easily pass into the belief in the existence of one or more gods. For savages would naturally attribute to spirits the same passions, the same love of vengeance or simplest form of justice, and the same affections which they themselves feel. The Fuegians appear to be in this respect in an intermediate condition, for when the surgeon on board the "Beagle" shot some young ducklings as specimens, York Minster declared in the most solemn manner, " Oh, Mr. Bynoe, " much rain, much snow, blow much ;" and this was evidently a retributive punishment for wasting human food. So again he related how, when his brother killed a " wild man," storms long raged, much rain and snow fell. Yet we could never discover that the Fuegians believed in what we should call a God, or practised any religious rites ; and Jemmy Button, with justifiable pride, stoutly maintained that there was no devil in his land. This latter assertion is the more remarkable, as with savages the belief in bad spirits is far more common than that in good ones. The feehog of religious devotion is a highly complex one, consisting of love, complete submission to an exalted and mysterious superior, a strong sense of dependence,^^ fear, reverence, gratitude, hope for the future, and perhaps other elements. No being could cxiDcricnce so complex an emotion anything which manifests power or ^^ See an able article on the movement is thought to be endowed ' Physical Elements of ileligion,' by with some form of life, and with !Mr. L. Owen Pike, in ' Anthropolog. mental faculties analogous to our Kevicw,' April, 1870, p. Ixiii. g6 The Desceitt of Man. Tart I, until advanced in his intellectual and moral faculties to at least a moderately high level. Nevertheless, we see some distant approach to this state of mind in the deep love of a dog for his master, associated with complete submission, some fear, and perhaps other feelings. The behaviour of a dog when returning to his master after an absence, and, as I may add, of a monkey to his beloved keeper, is widely diiferent from that towards their fellows. In the latter case the transports of joy appear to be somewhat less, and the sense of equality is shewn in every action. Professor Braubach goes so far as to maintain that a dog looks on his master as on a god.^^ The same high mental faculties which first led man to believe in miseen spiritual agencies, then in fetishism, polytheism, and ultimately in monotheism, would infallibly lead him, as long as his reasoning powers remained poorly developed, to various strange superstitions and customs. Many of these are terrible to think of — such as the sacrifice of human beings to a blood- loving god ; the trial of innocent persons by the ordeal of poison or fire ; witchcraft, &c. — yet it is well occasionally to reflect on these superstitions, for they shew us what an infinite debt of gratitude we owe to the improvement of our reason, to science, and to our accumulated knowledge. As Sir J. Lubbock''^ has well observed, " it is not too much to say that the horrible dread of " unknown evil hangs like a thick cloud over savage life, and " embitters every pleasure." These miserable and indirect consequences of our highest faculties may be compared with the incidental and occasional mistakes of the instincts of the lov/er animals. ^* ' Religion, Moral, &c., del* Dar- ^^ 'Prehistoric Times,' 2iid edit, win'schen Art-Lehre,' 1869, s. 53. p. 571. In this work (p. 571) It is said (Dr. W. Lauder Lindsay, there will be found an excellent 'Journal of Mental Science,' 1871, account of the many strange and p. 43), that Bacon long ago, and the capricious customs of savages, poet Burns, held the same notion. Chap. IV. Moral Sense. 97 CHAPTEK IV. CoMrAEisoN OF THE Mental Powers of Man and the Lower Animals— co??^mz(ecZ. Thf moral sense — Fundamental proposition — The qualities of social animals — Origin of sociability — Strutrgle between op])osed instincts — Man a social animal — Tlie more enduring social instincts conquer otlicr less persistent instincts — The social virtues alone regarded by savages — The self-regarding virtues acquired at a later stage of development — The importance of the judgment of the members of the same community on conduct — Transmission of moral tendencies — Summary. I FULLY subscribe to the judgment of those writers^ who maintain that of all the differences between man and the lower animals, the moral sense or conscience is by far the most important. This sense, as Mackintosh^ remarks, " has a " rightful supremacy over every other principle of human " action ;" it is summed up in that short but imperious word ouglit, so full of high significance. It is the most noble of all the attributes of man, leading him without a moment's hesita- tion to risk his life for that of a fellow-creature ; or after due deliberation, impelled simply by the deep feeling of right or duty, to sacrifice it in some great cause. Immanucl Kant exclaims, " Duty ! Wondrous thought, that workest neither by " fond insinuation, flattery, nor by any threat, but merely by " holding np thy naked law in the soul, and so extorting for " thyself always reyerence, if not always obedience ; before " whom all appetites are dumb, however secretly they rebel ; •' whence thy original?"^ This great question has been discussed by many writers^ of consummate ability ; and my sole excuse for touching on it, is the impossibility of here passing it over ; and because, as far as I know, no one has approached it exclusively from the side of natural history. The investigation possesses, also, some in- * See, for instance, on this subject, and Moral Science,' 18G8, p. 543- Quatrefages, ' Llnite de i'Espece 725) of twenty-six British authors Humaine,' 1861, p. 21, &c. who have written on this subject, - ' Dissertation on Ethical Philo- and whose names are familiar to sophy,' 1837, p. 231, &c. every reader ; to these, ^Ir. Bain's ' ' Metaphysics of Ethics,' trans- own name, and those of Mr. Lecky, lated by J. W. Semple, Edinburgh, Mr, Shadworth Hodgson, Sir J. 1836, p. 136. Lubbock, and others, mi|ht be * Mr. Bain gives a list (' Mental added. 98 The Descent of Man, Paet 1. dependent interest, as an attempt to see how far the study of the lower animals throws light on one of the highest psychical faculties of man. The folio v\dng proposition seems to me in a high degree probable — namely, that any animal whatever, endowed with well-marked social instincts,^ the parental and filial affections being here included, would inevitably acquire a moral sense or conscience, as soon as its intellectual powers had become as well, or nearly as well developed, as in man. For, firstly, the social instincts lead an animal to take pleasure in the society of its fellows, to feel a certain amount of sympathy with them, and to perform various services for them. The services may be of a definite and evidently instinctive nature ; or there may be only a wish and readiness, as with most of the higher social animals, to aid their fellows in certain general ways. But these feelings and services are by no means extended to all the individuals of the same species, only to those of the same association. Secondly, as soon as the mental faculties had become highly developed, images of all past actions and motives would be incessantly passing through the brain of each individual ; and that feeling of dissatisfaction, or even misery, which invariably results, as we shall hereafter see, from any unsatisfied instinct, would arise, as often as it was perceived that the enduring and always present social instinct had yielded to some other instinct, at the time stronger, but neither enduring in its nature, nor leaving ^ Six- B. Brodie, aftei observing all this, he also remarks, " if, as is that man is a social animal (' Psy- " my own belief, the moral feelings chological Enquiries,' 1854, p. 192), " are not innate, but acquired, they asks the pregnant question, " ought " are not for that reason less natu- " not this to settle the disputed " ral." It is with hesitation that I " question as to the existence of a venture to differ at all from so " moral sense ?" Similar ideas have profound a thinker, but it can probably occurred to many persons, hardly be disputed that the social as they did long ago to Marcus feelings are instinctive or innate in Aurelius. Mr. J. S. Mill speaks, in the lower animals ; and why should his celebrated work, * Utilitarian- they not be so in man ? Mr. Bain ism,' (1864, pp. 45, 46), of the social (see, for instance, 'The Emotions and feelino-s as a "powerful natural the Will,' 1865, p. 481) and others " sentiment," and as " the natural believe that the moral sense is ac- " basis of sentiment for utilitarian quired by each individual during " morality." Again he says, " Like his lifetime. On the general theory " the other acquired capacities above of evolution this is at least ex- " referred to, the moral faculty, if tremely improbable. The ignoring '• not a part of our nature, is of all transmitted mental qualities '• a natural out-growth from it ; will, as it seems to me, be hereafter " capable, like them, in a certain judged as a most serious blemish iu " small flegree of springing up spon- the works of Mr. Mill. " taneously." But in opposition to CiiAi'. IV. Moral Sense. 99 behind it a very vivid impression. It is clear that many in- stinctive desires, sucli as that of hunger, are in their nature of short duration; and after being satisfied, are not readily or vividly recalled. ThirdJy, after the power of language had been acquired, and the wishes of the community could be expressed, the common opinion how each member ought to act for the public good, would naturally become in a paramount degree the guide to action. But it should be borne in mind that how- ever great weight we may attribute to public oi)inion, our regard for the approbation and disapprobation of our fellows depends on sympathy, which, as we shall see, forms an essential part of the social instinct, and is indeed its foundation-stone, Lastly, habit in the individual would ultimately play a very important part in guiding the conduct of each member ; for the social in- stinct, together with sympathy, is, like any other instinct, greatly strengthened by habit, and so consequently would be obedience to the wishes and judgment of the community. These several subordinate propositions must now be discussed, and some of them at considerable length. It may be well first to premise that I do not wish to maintain that any strictly social animal, if its intellectual faculties were to become as active and as highly developed as in man, would acquire exactly the same moral sense as ours. In the same manner as various animals have some sense of beauty, though they admire widely different objects, so they might have a sense of right and wrong, though led by it to follow widely different lines of conduct. If, for instance, to take an extreme case, men were reared under precisely the same conditions as hive-bees, there can hardly be a doubt that our unmarried females would, like the worker-bees, think it a sacred duty to kill their brothers, and mothers would strive to kill their fertile daughters ; and no one would think of interfering.*^ Nevertheless, the bee, or any ^ Mr. H. Sidgwick i-emarks, in in Morals,' 'Theological Review,' an able discussion on this subject April, 1872, p. 188-191) on the (the 'Academy,' June 15th, 1872, same illustration, says, the j)rin- (p. 231), "a superior bee, we may ciplcs of social duty would be thus " feel sure, would aspire to a milder reversed ; and by this, I presume, " solution of the population ques- she means that the fulfilment of a " tion." Judging, however, from social duty would tend to tlie injury the habits of many or most savages, ot" individuals ; but she overlooks man solves the problem by famale the fact, which she would doubtless infanticide, polyandry and promis- admit, that tlie instincts of the bee cuous intercourse ; therefore it may have been acquired for the good of well be doubted whether it would the community. She goes so far as be by a milder method. Jliss to say that if the theory of ethics Cobbe, in commenting ('Darwinism advocated in this chapter were ever 100 The Descent of Ma]i. Part I. other social animal^ would gain in our supposed case, as it appears to me, some feeling of right or wrong, or a conscience. For each individual would have an inward sense of possessing certain stronger or more enduring instincts, and others less strong or enduring ; so that there would often be a struggle as to which impulse should be followed; and satisfaction, dissatis- faction, or even misery would be felt, as past impressions were compared during their incessant passage through the mind. In this case an inward monitor would tell the animal that it would have been better to have followed the one impulse rather than the other. The one course ought to have been followed, and the other ought not ; the one would have been right and the other wrong ; but to these terms I shall recur. Sociahility. — Animals of many kinds are social ; we find even distinct species living together ; for example, some American monkeys ; and united flocks of rooks, jackdaws, and starlings. Man shews the same feeling in his strong love for the dog, which the dog returns with interest. Every one must have noticed how miserable horses, dogs, sheep, &c., are when separated from their companions, and what strong mutual affection the two former kinds, at least, shew on theii* reunion. It is curious to speculate on the feelings of a dog, who will rest peacefully for hours in a room with his master or any of the family, without the least notice being taken of him ; but if left for a short time by himself, barks or howls dismally. "We will confine our attention to the higher social animals ; and pass over insects, although some of these are social, and aid one another in many important ways. The most common mutual service in the higher animals is to warn one another of danger by means of the united senses of all. Every sportsman knows, as Dr. Jaeger remarks," how difficult it is to ajDproach animals in a herd or troop. Wild horses and cattle do not, I believe, make any danger-signal; but the attitude of any one of them who first discovers an enemy, warns the others. Eabbits stamp loudly on the ground with their hind-feet as a signal : sheep and chamois do the same with their forefeet, uttering likewise a whistle. Many birds, and some mammals, post sentinels, which in the case of seals are said^ generally to be the females. The leader generally accepted, " I cannot but earth is not held by many persons " believe that in the hour of their on so weak a tenure. " triumph would be sounded the " ' Die Darwin'sche Theorie,' s, *' knell of the virtue of mankind '." 101, It is to be hoped that the belief in * Mr. R. Brown in ' Proc. Zoolog. the permanence of virtue on this %athy, animals exhibit other qualities connected with the social instincts, which in us would be called moral ; and I agree with Agassiz ^^ that dogs possess something very hke a conscience. Dogs possess some power of self-command, and this does not appear to be wholly the result of fear. As Braubach'^ remarks, they will refrain from stealing food in the absence of their master. They have long been accepted as the very type of fidelity and obedience. But the elei)hant is likewise very faith- ful to his driver or keeper, and probably considers him as the '* As Mr. Bain states, "effective ^^ ' De I'Esp&ce ct dc la Classe,' " aid to a sufferer springs from sym- 18(59, p. 97. " pathy proper :" 'Mental and Moral *' ' Die Darwin'sclic Art-Lehre,* Science,' 1868, p. 245. 18G9, s. 54. *^ 'Thierleben, B. i. s, 85. T04 The Descent of Man. Pari I. leader of the lierd. Dr. Hooker informs me that an elephant, which he was riding in India, became so deeply bogged that he remained stnck fast until the next day, when he was extricated by men with ropes. Under snch circumstances elephants will seize with their trunks any object, dead or alive, to place under their knees, to prevent their sinking deeper in the mud ; and the driver was dreadfully afraid lest the animal should have seized Dr. Hooker and crushed him to death. But the driver himself, as Dr. Hooker was assured, ran no risk. This forbearance under an emergency so dreadful for a heavy animal, is a wonderful proof of noble fidelity .^^ All animals living in a body, which defend themselves or attack their enemies in concert, must indeed be in some degree faithful to one another ; and those that follow a leader must be in some degree obedient. "When the baboons in Abyssinia ^^ plunder a garden, they silently follow their leader ; and if an imprudent young animal makes a noise, he receives a slap from the others to teach him silence and obedience. j\Ir. Galton, who has had excellent opportunities for observing the half-wild cattle in S. Africa, says,-" that they cannot endure even a momentary separa- tion from the herd. They are essentially slavish, and accept the common determination, seeking no better lot than to be led by any one ox who has enough self-reliance to accept the position. The men who break in these animals for harness, watch assidu- ously for those who, by grazing apart, shew a self-reliant dis- position, and these they train as fore-oxen. Mr. Galton adds that such animals are rare and valuable ; and if many were born they would soon be eliminated, as lions are always on the look- out for the individuals which wander from the herd. "With respect to the impulse which leads certain animals to associate together, and to aid one another in many ways, we may infer that in most cases they are impelled by the same sense of satisfaction or pleasure which they experience in per- forming other instinctive actions; or by the same sense of dissatisfaction as when other instinctive actions are checked. ^Ye see this in innumerable instances, and it is illustrated in a striking manner by the acquired instincts of our domesticated animals ; thus a young shepherd-dog delights in driving and running round a flock of sheep, but not in worrying them ; a young fox-hound delights in hunting a fox, whilst some other kinds of dogs, as I have witnessed, utterly disregard foxes. What ^^ See also Hooker's ' Himalayan 20 See his extremely interesting Journals,' vol. ii., 1854, p. 333. paper on ' Gregariousness in Cattle, ** Brehm, ' Thierleben,' B. i. s. and in Man,' ' Macmiilan's Mag.' Feb. 7G. 1871, p. 353. Chap. IV. Moral Sense. 105 a strong feeling of inward satisfaction must impel a bird, so full of activity, to brood day after day over her eggs. Migratory birds are quite miserable if stopped from migrating; perliajjs they enjoy starting on their long flight ; but it is hard to believe that the poor pinioned goose, described by Audubon, which started on foot at the proper time for its journey of probably more than a thousand miles, could have felt any joy in doing so. Some instincts are determined solely by painful feelings, as by fear, which leads to self-preservation, and is in some cases directed towards special enemies. No one, I presume, can analyse the sensations of pleasure or pain. In many instances, however, it is probable that instincts are persistently followed from the mere force of inheritance, without the stimulus of either l">leasure or pain. A young pointer, when it tirst scents game, apparently cannot help pointing. A squirrel in a cage who pais the nuts which it cannot eat, as if to bury them in the ground, can hardly be thought to act thus, either from pleasure or pain. Hence the common assumption that men must be impelled to every action by experiencing some pleasure or pain may be erro- neous. Although a habit may be blindly and implicitly followed, independently of any j^lcasure or pain felt at the moment, yet if it be forcibly and abruptly checked, a vague sense of dissatisfaction is generally experienced. It has often been assumed that animals were in the first place rendered social, and that they feel as a consequence uncomfort- able when separated from each other, and comfortable whilst together ; but it is a more probable view that these sensations were first developed, in order that those animals which would profit by living in society, should be induced to live together, in the same manner as the sense of hunger and the pleasure of eating were, no doubt, first acquired in order to induce animals to eat. The feeling of j^lcasure from society is probably an extension of the parental or filial affections, since the social instinct seems to be developed by the young remaining for a long time with their parents; and this extension may be attri- buted in part to habit, but chiefly to natural selection. With tliose animals which were benefited by living in close association, the individuals which took the greatest pleasure in society would best escape various dangers; whilst those that cared least for their comrades, and lived solitary, would perish in greater numbers. With respect to the origin of the parental and fihal affections, which apparently lie at the base of the social instincts, we know not the steps by which they have been gained; but we may infer that it has been to a large extent through natural selection. So it has almost certainly 6 io6 The Descent of Man. Part T. been with the unusual aiid opposite feeling of hatred between the nearest relations, as with the worker-bees which kill their brother-drones, and with the queen-bees which kill their daughter-queens; the desire to destroy their nearest relations having been in this case of service to the community. Parental affection, or some feeling which replaces it, has been developed in certain animals extremely low in the scale, for example, in star-fishes and spiders. It is also occasionally present in a few members alone in a whole group of animals, as in the genus Forficula, or earwigs. The all-important emotion of sympathy is distinct from that of love. A mother may passionately love her sleeping and passive infant, but she can hardly at such times be said to feel • sympathy for it. The love of a man for his dog is distinct from sympathy, and so is that of a dog for his master. Adam Smith formerly argued, as has Mr. Bain recently, that the basis of sympathy Hes in our strong retentiveness of former states of pain or pleasure. Hence, "the sight of another person en- " during hunger, cold, fatigue, revives in us some recollection of " these states, which are painful even in idea." We are thus impelled to relieve the sufferings of another, in order that our own painful feelings may be at the same time relieved. In Hke manner we are led to participate in the pleasures of others.^' But I cannot see how this view explains the fact that sympathy is excited, in an immeasurably stronger degree, by a beloved, than by an indifferent person. The mere sight of suffering, independently of love, would suffice to call up in us vivid recollections and associations. The explanation may lie in the fact that, with all animals, sympathy is dhected solely towards the members of the same community, and therefore towards known, and more or less beloved members, but not to all the individuals of the same species. This fact is not more sur- prising than that the fears of many animals should be directed against special enemies. Species which are not social, such as lions and tigers, no doubt feel sympathy for the suffering of tbeir own young, but not for that of any other animal. With 21 See the first and striking " or others in his stead, may make chapter in Adam Smith's ' Theory " up, by sympathy and good offices of Moral Sentiments.' Also Mr. " returned, for all the sacrifice." Bain's ' Mental and Moral Science,' But if, as appears to be the case, 1868, p. 244, and 275-282. Mr. sympathy is strictly an instinct, Bain states, that "sympathy is, in- its exercise would give direct plea- " directly, a source of pleasure to sure, in the same manner as the " the sympathiser ;" and he accounts exercise, as before remarked, of al- f(ir this through reciprocity. He most every other instinct, remarks that " the person benefited, CtiAP. IV. Moral Sense. 107 mankind, sclfislincss, experience, and imitation, probably add, as Mr. Bain has shown, to the power of sympathy ; for we are led by the hope of receiving good in return to perform acts of sympathetic kindness to others ; and sympathy is much strengthened by habit. In however complex a manner this feeling may have originated, as it is one of high importance to all those animals which aid and defend one another, it will have been increased through natural selection ; for those commu- nities, which included the greatest number of the most sympa- thetic members, would flourish best, and rear the greatest number of offspring. It is, however, impossible to decide in many cases whether certain social instincts have been acquired through natural selection, or are the indirect result of other instincts and faculties, such as sympathy, reason, experience, and a tendency to imitation ; or again, whether they are simply the result of long-continued habit. So remarkable an instinct as the placing sentinels to warn the community of danger, can hardly have been the indirect result of any of these faculties ; it must, there- fore, have been directly acquired. On the other hand, the habit followed by the males of some social animals of defending the community, and of attacking their enemies or their prey in concert, may perhaps have originated from mutual sym^Dathy ; but courage, and in most cases strength, must have been previously acquired, probably through natural selection. Of the various instincts and habits, some are mnch stronger than others ; that is, some either give more pleasure in their performance, and more distress in their prevention, than others ; or, ^hich is probably quite as important, they are, through inheritance, more persistently followed, without exciting any special feeling of pleasure or pain. We are ourselves conscious that some habits are much more difficult to cure or change than others. Hence a struggle may often be observed in animals between different instincts, or between an instinct and some habitual disposition; as when a dog rushes after a hare, is rebuked, pauses, hesitates, pursues again, or returns ashamed to his master ; or as between the love of a female dog for her young l-)uppies and for her master,— for she may be seen to slink away to them, as if half ashamed of not accompanying her master. But the most carious instance known to me of one instinct getting the better of another, is the migratory instinct conquer- ing the maternal instinct. The former is wonderfully strong; a confined bird will at the proper season beat her breast against the wires of her cage, until it is bare and bloody. It causes young salmon to leap out of the fresh water, in which they could io8 The: Descent of Man. Part T. continue to exist, and thus unintentionally to commit suicide. Every one knows how strong the maternal instinct is, leading even timid birds to face great danger, though with hesitation, and in opposition to the instinct of self-preservation. Neverthe- less, the migratory instinct is so powerful, that late in the autumn swallows, house-martins, and swifts frequently desert their tender young, leaving them to perish miserably in their nests.^^ We can perceive that an instinctive impulse, if it be in any way more beneficial to a species than some other or ojDposed instinct, would be rendered the more potent of the two through natural selection ; for the individuals which had it most strongly developed would survive in larger numbers. Whether this is the case with the migratory in comparison with the maternal instinct, may be doubted. The great persistence, or steady action of the former at certain seasons of the year during the whole day, may give it for a time paramount force. Man a social animal. — Every one will admit that man is a social being. We see this in his dislike of solitude, and. in his wish for society beyond that of his own family. Solitary con- finement is one of the severest punishments which can be inflicted. Some authors suppose that man primevally lived in single families ; but at the present day, though single families, or only two or three together, roam the solitudes of some savage lands, they always, as far as I can discover, hold friendly relations with other families inhabiting the same district. Such families occasionally meet in council, and unite for their common defence. It is no argument against savage man being a social animal, that the tribes inhabiting adjacent districts are almost always at war with each other ; for the social instincts never extend to all the individuals of the same species. Judging from the analogy of the majority of the Quadrumana, it is probable that the early ape-like progenitors of man were likewise social ; but thLs is not of much importance for us. Although man, as ^* This fact, the Rev. L. Jenyns hatched. Many birds, not yet old states (see his edition of ' White's enough for a prolonged flight, are Nat. Hist, of Selborne,' 1853, p. likewise deserted and left behind. 204) was first recorded by the illus- See Blackwall, 'Researches in Zoo- trious Jenner, in 'Phil. Transact,' logy,' 1834, pp. 108, 118. For some 1824, and has since been confirmed additional evidence, although this by several observers, especially by is not wanted, see Leroy, ' Lettres Mr. Blackwall. This latter careful Phil.' 1802, p. 217. For Swifts, observer examined, late in the Gould's ' Introduction to the Birds autumn, during two years, thirty- of Great Britain,' 1823, p. o. Simi- six nests ; he found that twelve lar cases have been observed in contained young dead birds, five Canada by Mr. Adams ; ' Pop. contained eggs on the point of being Science Review,' July 1873, p. hatched, and three, eggs not nearly 283. CiiAP. IV. Moral Sense. 109 ho now exists, has few special instincts, having lost any which his early progenitors may have possessed, tliis is no reason wliy he should not have retained from an extremely remote period some degree of instinctive love and sympathy for his fellows. We are indeed all conscious that we do possess such sympathetic feelings ; -^ but our consciousness does not tell ns whether they are instinctive, having originated long ago in the same manner as with the lower animals, or whether tliey have been acquired by each of us during our early years. As man is a social animal, it is almost certain that he would inherit a tendency to be faithful to his comrades, and obedient to the leader of his tribe ; for these qualities are connnon to most social animals. lie would consequently possess some capacity for self-command. lie would from an inherited tendency be willing to defend, in concert with others, his fellow-men ; and would be ready to aid them in any way, which did not too greatly interfere with his own welfare or his own strong desires. The social animals which stand at the bottom of the scale are guided almost exclusively, and those which stand higher in the scale are largely guided, by special instincts in the aid which they give to the members of the same community ; but they arc likewise in part impelled by mutual love and sympathy, assisted apparently by some amount of reason. Although man, as just remarked, has no special instincts to tell him how to aid his fellow-men, he still has the impulse, and with his improved intellectual faculties would naturally be much guided in this respect by reason and experience. Instinctive sympathy would also cause him to value highly the approbation of his fello^^s ; for, as Mr. Bain has clearly shewn,^^ the love of praise and the strong feeling of glory, and the still stronger horror of scorn and infamy, " are due to the workings of sympathy." Conse- quently man would be influenced in the highest degree by the wishes, approbation, and blame of his fellow-men, as expressed by their gestures and language. Thus the social instincts, which must have been acquired by man in a very rude state, and probably even by his early ape-like progenitors, still give the impulse to some of his best actions : but his actions are in a higher degree determined by the expressed wishes and judgment 2' Hume remarks ('An Enquiiy *' of the former . . . communicates Concerning the Principles of Morals,' "a secret joy; the appearance of edit, of 1751, p. lo2), "There seems "the latter . . . throws a melau- " a necessity for confessing that the " choly damp ov6r the imagiua- " happiness and misery of others " tion." "are not spectacles altogether in- '^■' 'Mental ami Moral Science,' " different to us. but that the view ISGS, p. 2.04 no TJie Descent of Man. Tart 1. of his fellow-men, and unfortunately very often by his own strong selfish desires. But as love, sympathy and self-command become strengthened by habit, and as the power of reasoning becomes clearer, so that man can value justly the judgments of his fellows, he will feel himself impelled, apart from any transitory pleasure or pain, to certain lines of conduct. He might then declare — not that any barbarian or uncultivated man could thus think — I am the supreme judge of my own conduct, and in the words of Kant, I will not in my own person violate the dignity of humanity. The more enduring Socid Instincts conquer the less 2yersisfent Instincts. — We have not, however, as yet considered the main point, on which, from our present point of view, the whole question of the moral sense turns. Why should a man feel that he ought to obey one instinctive desii*e rather than another ? "Why is he bitterly regretful, if he has yielded to a strong sense of self-preservation, and has not risked his life to save that of a fellow-creature ? or why does he regret having stolen food from hunger ? It is evident in the first place, that with mankind the instinc- tive impulses have different degi-ees of strength ; a savage will risk his own life to save that of a member of the same community, but will be wholly indifferent about a stranger : a young and timid mother urged by the maternal instinct will, without a moment's hesitation, run the greatest danger for her own infant, but not for a mere fellow-creature. Nevertheless many a civilized man, or even boy, who never before risked his life for andther, but full of courage and sympathy, has diregarded the instinct of self-preservation, and plunged at once into a torrent to save a drowning man, though a stranger. In this case man is impelled by the same instinctive motive, which made the heroic little American monkey, formerly described, save his keeper, by attacking the great and dreaded baboon. Such actions as the above appear to be the simple result of the gi-eater strength of the social or maternal instincts than that of any other instinct or motive; for they are perfonned too instan- taneously for reflection, or for pleasure or pain to be felt at the time ; though, if prevented by any cause, distress or even misery might be felt. In a timid man, on the other hand, the instinct of self-preservation might be so strong, that he would be unable to force himself to run any such risk, perhaps not even for his own child. I am aware that some persons maintain that actions performed impulsively, as in the above cases, do not come under the domijiion of the moral sense, and cannot be called moral. They Chap. iV. Mora/ Sense. 1 1 1 confine this term to actions done deliberately, after a victory over opposing desires, or when prompted l)y some exalted motive. But it appears scarcely possible to draw any clear line of distinction of this kind.'-^^ As far as exalted motives are concerned, many instances have been recorded of savages, destitute of any feeling of general benevolence towards mankind, and not guided by any religious motive, who have deliberately sacrificed their lives as i)risoners,^'' rather than betray their comrades; and surely their conduct ought to be considered as moral. As far as deliberation, and the victory over opposing motives are concerned, animals may be seen doubting between opposed instincts, in rescuing their offspring or comrades from danger ; yet their actions, though done for the good of others, are not called moral. Moreover, anything performed very often by us, will at last be done without deliberation or hesitation, and can then hardly be distinguished from an instinct; yet surely no one will pretend that such an action ceases to be moral. On the contrary, w^e all feel that an act cannot be considered as perfect, or as performed in the most noble manner, unless it be done impulsively, without deliberation or effort, in the same manner as by a man in whom the requisite qualities are innate. He who is forced to overcome his fear or want of sympathy before he acts, deserves, however, in one way higher credit than the man whose innate disposition leads him to a good act without effort. As we cannot distinguish between motives, we* rank all actions of a certain class as moral, if performed by a moral being. A moral being is one who is capable of comparing his past and future actions or motives, and of approving or disapproving of them. "We have no reason to suppose that any of the lower animals have this capacity ; therefore, wdien a Newfoundland dog drags a child out of the water, or a monkey faces danger to rescue its comrade, or takes charge of an orphan monkey, we do not call its conduct moral. But in the case of man, who alone can with certainty be ranked as a moral being, actions of a certain class are called moral, whether performed deliberately, after a struggle with oj^posing "^^ I refer here to the distinction " material and formal morality is between what has been called ma- " as irrelevant as other siuh dis- terial and formal morality. I am " tinctions." glad to find that Prof. Huxley ('Cri- ^g j have given one such case, tiques and Addresses,' 1873, p. 287) namely of three Patagonian Indians takes the same view on this subject who jtreferred being shot, one after as I do. Mr. Leslie Stc])hen re- the other, to betraying the ]»lans of marks (' Essavs on Freethinking and their companions in war (' Journal Plain Speaking,' 1873, p. 8;'.)/" the of Researches,' 1845, p. 103). " metaphysical distinction betwceu 112 The Descent of Man. Part I. motives, or impulsively through instinct, or from the effects of slowly-gained habit. But to return to our more immediate subject. Although some uistincts are more powerful than others, and thus lead to cor- responding actions, yet it is untenable, that in man the social instincts (including the love of praise and fear of blame) possess greater strength, or have, through long habit, acquired greater strength than the instincts of self-preservation, hunger, lust, vengeance, &c. Why then does man regret, even though trying to banish such regret, that he has followed the one natural impulse rather than the other ; and why does he further feel that he ought to regret his conduct ? Man in this respect differs profoundly from the lower animals. Nevertheless we can, I think, see with some degree of clearness the reason of this difference. Man, from the activity of his mental faculties, cannot avoid reflection : past impressions and images are incessantly and clearly passing through his mind. Now with those animals which live permanently in a body, the social instincts are ever present and persistent. Such animals are always ready to utter the danger-signal, to defend the community, and to give aid to their fellows in accordance w^ith their habits ; they feel at all times, without the stimulus of any special passion or desire, some degree of love and sympathy for them ; they are unhappy if long separated from them, and always happy to be again m their company. So it is with ourselves. Even when we are quite alone, how often do we think with pleasure or pain of what others think of us, — of their imagined aijprobation or disapprobation; and this all follows from sympathy, a funda- mental element of the social instincts. A man who possessed no trace of such instincts would be an unnatural monster. On the other hand, the desire to satisfy hunger, or any passion such as vengeance, is in its nature temporary, and can for a time be fully satisfied. Nor is it easy, jDcrhaps hardly possible, to call up with complete vividness the feeling, for instance, of hunger ; nor indeed, as has often been remarked, of any suffering. The instinct of self-preservation is not felt except in the presence of danger; and many a coward has thought himself brave until he has met his enemy face to face. The wish for another man's property is jDsrhaps as persistent a desire as any that can be named; but even in this case the satisfaction of actual pos- session is generally a weaker feeling than the desire : many a thief, if not a habitual one, after success has wondered why he stole some article.^ ^^ Enmity or hatred seems also perhaps more so than auy other to be a highly persistent feeling, that can be named. Envy is de- Chap. IV. Moral Sense. 1 1 3 A man cannot jircYcnt past impressions often repassing tlirongli liis mind ; lie will thns be driven to make a comparison between tbo imjiressions of past Imnger, vengeance satisfied, or danger shunned at other men's cost, with the almost ever-present instinct of sympathy, and with his early knowledge of what others consider as praise v/Orthy or blameable. This knowledge cannot be banished from his mind, and from instinctive sympathy is esteemed of great moment. He will then feel as if he had been baulked in following a present instinct or habit, and this with all animals causes dissatisfaction, or even misery. The above case of the swallow affords an illustration, though of a reversed nature, of a temporary though for the time strongly persistent instinct con(iuering another instinct, which is usually dominant over all others. At the proper season these birds seem all day long to be impressed with the desire to migrate ; their habits change ; they become restless, are noisy, and con- gregate in flocks. Whilst the mother-bird is feeding, or brooding over her nestlings, the maternal instinct is probably stronger than the migratory ; but the instinct wiiich is the more persis- tent gains the victory, and at last, at a moment when her young ones are not in sight, slic takes flight and deserts them. When arrived at the end of her long journey, and the migratory instinct has ceased to act, what an agony of remorse the bird would feel, if, from being endowed with great mental activity, she could not prevent the image constantly passing through her mind, of her young ones perishing in the bleak north from cold and hunger. fined as hatred of another for some had done him an injiirv and liad excellence or success; and Bacon become his enemy, iv'or is it pro- insists (Essay ix.), " Of all otlier bable that the primitive conscience " affections envy is the most im- would reproach a man lor injurin;-- " port une and continual." Dogs ai-e his enemy: ratlier it would re- very apt to hate both strange men proach him, if he had not revenged and strange dogs, esjiecially if they himself. To do good in return lor live near at hand, but do not beU)ng evil, to love your enemy, is a height to the same family, tribe, or clan; of morality to which it mav^be this feeling would thus seem to be doubted whether the social instincts innate, and is certainly a most per- would, by themselves, have ever led sistent one. It seems to be the us. It is necessary that these in- complement and converse of the stincts, together with sympathy, true social instinct. From what should have been highly cultivated we hear of savages, it would appear and extended l)y the aid of reason, that something of the same kind instruction, and the love or fear of holds good with them. If this be God, before any such golden rule so, it would be a small step in would ever be thought of and any one to transfer such feelings to obeyed. any member of the same tribe if he 1 14 The Descent of Man. Part I. A-t the moment of action, man will no doubt be apt to follow the stronger impulse; and though this may occasionally prompt him to the noblest deeds, it will more commonly lead him to gratify his own desires at the expense of other men. But after their gratification, when past and weaker impressions are judged by the ever-enduring social instinct, and by his deep regard for the good opinion of his fellows, retribution will surely come. He will then feel remorse, repentance, regret, or shame; this latter feeling, however, relates almost exclusively to the judgment of others. He will consequently resolve more or less firmly to act differently for the future ; and this is conscience ; for conscience looks backwards, and seiwes as a guide for the future. The nature and strength of the feelings which we call regret, shame, repentance or remorse, depend apparently not only on the strength of the violated instinct, but partly on the strength of the temptation, and often still more on the judgment of our fellows. How far each man values the appreciation of others, depends on the strength of his innate or acquired feeling of sympathy ; and on his own capacity for reasoning out the remote consequences of his acts. Another element is most important, although not necessary, the reverence or fear of the Gods, or Spirits believed in by each man : and this applies especially in cases of remorse. Several critics have objected that though some shght regret or repentance may be explained by the view advocated in this chapter, it is impossible thns to account for the soul-shaking feeling of remorse. But I can see little force in this objection. My critics do not define what they mean by remorse, and I can find no definition implying more than an overwhelming sense of repentance. Eemorse seems to bear the same relation to rej^entance, as rage does to anger, or agony to pain. It is far from strange that an instinct so strong and so generally admired, as maternal love, should, if disobeyed, lead to the deepest misery, as soon as the impression of the past cause of disobedience is weakened. Even when an action is opposed to no special instinct, merely to know that our friends and equals despise ns for it is enough to cause great misery. Who can doubt that the refusal to fight a duel tlu-ough fear has caused many men an agony of shame ? Many a Hindoo, it is said, has been stirred to the bottom of his soul by having partaken of unclean food. Here is another case of what must, I think, be called remorse. Dr. Landor acted as a magistrate in West Australia, and relates,"* that a native on his farm, after losing one of his wives from disease, came and said that " he was 23 ' Insanity in Relation to Law;' Ontario, United States, 1871, p. 14. CuAP. IV. Moral Soisc. 1 1 5 " going to a distant tribe to spear a woman, to satisfy liis sense '' of duty to liis wife. I told liim that if lie did so, I would " send him to prison for life. He remained about the farm for " some months, but got exceedingly thin, and complained that " he could not rest or cat, that his wife's spirit was haunting " him, because he had not taken a life for hers. I was in- " exorable, and assured him that nothing should save him if he " did." Nevertheless the man disappeared for more than a year, and then returned in high condition ; and his other wife told Dr. Landor that her husband had taken the life of a woman belonging to a distant tribe ; but it was impossible to obtain legal evidence of the act. The breach of a rule held sacred by the tribe, will thus, as it seems, give rise to the deepest feelings, — and this quite apart from the social instincts, excepting in so far as the rule is grounded on the judgment of the community. How so many strange superstitions have arisen throughout the world we know not ; nor can wc tell how some real and great crimes, such as incest, have come to be held in an abhorrence (which is not however quite universal) by the lowest savages. It is even doubtful whether in some tribes incest would be looked on with greater horror, than would the marriage of a man with a woman bearing the same name, though not a relation. " To " violate this law is a crime which the Australians hold in the " greatest abhorrence, in this agreeing exactly with certain " tribes of North America. When the question is put in either " district, is it worse to kill a girl of a foreign tribe, or to marry " a girl of one's own, an answer just opposite to oui's would be given without hesitation." ^^ We may, therefore, reject the belief, lately insisted on by some writers, that the abhorrence of incest is due to our possessing a special God -implanted con- science. On the whole it is intelligible, that a man urged by so powerful a sentiment as remorse, though arising as above explained, should be led to act in a manner, which he has been taught to believe serves as an expiation, such as delivering himself up to justice. Man prompted by his conscience, will through long habit acquire such perfect self-command, that his desires and passions will at last yield instantly and without a struggle to his social sympathies and instincts, including his feeling for the judgment of his fellows. The still hungry, or the still revengeful man will not think of stealing food, or of wreaking his vengeance. It is possible, or as we shall hereafter see, even probable, that the habit of self- command may, like other habits, be inherited. Thus at last man '* E. B. Tylor iu 'Contemporary Review,' April, 1873, p. 707. 1 1 6 The Descent of Man. Part I comes to feel, through acquired and perhaps inherited habit, that it is best for him to obey his more persistent impulses. The imperious word oz((/A^ seems merely to imply the consciousness of the existence of a rule of conduct, however it may have originated. Formerly it must have been often vehemently urged that an insulted gentleman ought to fight a duel. We even say that a pointer ouglit to point, and a retriever to retrieve game. If they fail to do so, they fail in their duty and act wrongly. If any desire or instinct leading to an action opposed to the good of others still appears, when recalled to mind, as strong as, or stronger than, the social instinct, a man will feel no keen regret at having followed it ; but he will be conscious that if his conduct were known to his fellows, it would meet with their disapprobation ; and few are so destitute of sympathy as not to feel discomfort when this is realised. If he has no such sympathy, and if his desires leading to bad actions are at the time strong, and when recalled are not over-mastered by the persistent social instincts, and the judgment of others, then he is essentially a bad man ; ^" and the sole restraining motive left is the fear of punishment, and the conviction that in the long run it would be best for his own selfish interests to regard the good of others rather than his own. It is obvious that every one may with an easy conscience gratify his own desires, if they do not interfere with his social instincts, that is with the good of others ; but in order to be quite free from self-rejDroach, or at least of anxiety, it is almost neces- sary for him to avoid the disapprobation, whether reasonable or not, of his fellow-men. Nor must he break through the fixed habits of his life, especially if these are supported by reason; for if he does, he will assuredly feel dissatisfaction. He must likewise avoid the reprobation of the one God or gods in whom, according to his knowledge or superstition, he may believe ; but in this case the additional fear of divine punishment often supervenes. The strictly Social Virtues at first alone regarded. — The above view of the origin and nature of the moral sense, which tells us what we ought to do, and of the conscience which reproves us if we disobey it, accords well with what we see of the early and undeveloped condition of this faculty in mankind. The virtues which must be practised, at least generally, by rude men, so *" Dr. Prosper Despine, in his many curious cases of the worst ' Psychologic Naturelle,' 1868 (torn. criminals, who apparently have been I. p, 243; torn. ii. p. 1G9) gives entirely destitute of conscience. CiiAp IV. Moral Sense. 117 tliat they may associate in a body, arc those which arc still recognised as the most important. But they are practised almost exclusively in relation to the men of the same tribe ; and their opposites are not regarded as crimes in relation to the men of other tribes. No tribe could hold together if murder, robbery, treachery, &c., were common; consequently such crimes within the limits of the same tribe "are branded with "everlasting infamy ;"^^ but excite no such sentiment beyond these limits. A North-American Indian is well pleased with himself, and is honoured by others, when he scalps a man of another tribe ; and a Dyak cuts off the head of an unoflfending person, and dries it as a trophy. The murder of infants has prevailed on the largest scale throughout the world,^^ and has met with no reproach ; but infcinticide, especially of females, has been thought to be good for the tribe, or at least not injurious. Suicide during former times was not generally considered as a crime,^^ but rather, from the courage displayed, as an honourable act ; and it is still practised by some semi-civilised and savage nations without reproach, for it does not obviously concern others of the tribe. It has been recorded that an Indian Thug conscientiously regretted that he had not robbed and strangled as many travellers as did his father before him. In a rude state of civilisation the robbery of strangers is, indeed, generally considered as honourable. Slavery, although in some ways beneficial during ancient times,^'* is a great crime ; yet it was not so regarded until quite recently, even by the most civilized nations. And this was especially the case, because the slaves belonged in general to a race different from that of their masters. As barbarians do not regard the opinion of their women, wives are commonly treated like slaves. Most savages are utterly indiifcrcnt to the sufferings of strangers, or even delight in witnessicg them. It is well 3' See an able article in the of European Morals,' vol. i. 18G9, * North British Review,' 1867, p. p. 223. With respect to savages, 395. See also Mr. W. Bagehot/s ^Mr. Winwood Keade informs me articles on the Importance of Obe- that the negroes of West Africa dience and Coherence to Primitive often commit suicide. It is well Man, in the 'Fortnightly Review,' known how common it was amongst 1867, p. 529, and 1868, p. 457, &c. the miserable aborigines of South ^2 The fullest account which I America, after the Spanish conquest, have met with is by Dr. Gerland, in For New Zealand, see the voyage of his 'Ueber dan Aussterben der the " Novara," and for the Aleutian Naturvolker,' 1868; but I shall Islands, Miiiler, as quoted by Hou- have to recur to the subject of zeau, ' Les Facultes Mentalcs,' &c., infanticide in a future chapter. torn. ii. p. 136. '^ See the very interesting discus- ^^ Sec Mr. Bagehot, ' Physics and sicn on Suicide in Lecky's 'History Politics,' 1872, p. 72. 1 18 The Descent of Man, Part I. known that the women and children of the North- American Indians aided in torturing their enemies. Some savages take a horrid pleasure in cruelty to animals/^ and humanity is an unknown •virtue. Nevertheless, besides the family affections, kindness is common, especially during sickness, between the members of the same tribe, and is sometimes extended beyond these limits. Mungo Park's touching account of the kindness of the negro women of the interior to him is well known. Many instances could be given of the noble fidehty of savages towards each other, but not to strangers ; common experience justifies the maxim of the Spaniard, "Never, never trust an Indian." There cannot be fidelity without truth ; and this fundamental virtue is not rare between the members of the same tribe : thus Mungo Park heard the negi-o women teaching their young childi-en to love the truth. This, again, is one of the virtues which becomes so deeply rooted in the mind, that it is sometimes practised by savages, even at a high cost, towards strangers ; but to lie to your enemy has rarely been thought a sin, as the history of modern diplomacy too plainly shews. As soon as a tribe has a recognised leader, disobedience becomes a crime, and even abject submission is looked at as a sacred virtue. As during rude times no man can be useful or faithful to his tribe without courage, this quality has universally been placed in the highest rank; and although in civihsed countries a good yet timid man may be far more useful to the community than a brave one, we cannot helj) instinctively honouring the latter above a coward, however benevolent. Prudence, on the other hand, which does not concern the welfare of others, though a very useful virtue, has never been highly esteemed. As no man can practise the virtues necessary for the welfare of his tribe without self-sacrifice, self-command, and the power of endurance, these qualities have been at all times highly and most justly valued. The American savage voluntarily submits to the most horrid tortui-es without a groan, to prove and strengthen his fortitude and courage; and we cannot help admiring him, or even an Indian Fakir, who, from a foolish religious motive, swings suspended by a hook buried in his flesh. The other so called self-regarding virtues, which do not obviously, though they may really, affect the welfare of the tribe, have never been esteemed by savages, though now highly ax^preciated by civilised nations. The greatest intemperance ^^ See, for instance, Mi'. Hamilton's account of the Kaffirs, ' Anthro- pological Review,' 1870, p. xv. CiiAi'. IV. Moral Sense. 119 is no rcproach with savages. Utter licentiousness, and un- natural crimes, prevail to an astounding extent.^^ As soon, however, as marriage, whether polygamous, or monogamous, becomes common, jealousy will lead to the inculcation of female virtue; and this, being honoured, will tend to spread to tlie unmarried females. How slowly it spreads to the male sex, we see at the present day. Chastity eminently requires self- command; therefore it has been honoured from a very early period in the moral history of civilised man. As a consequence of this, the senseless practice of celibacy has been ranked from a remote period as a virtue.^^ The hatred of indecency, which appears to us so natural as to be thought innate, and which is so valuable an aid to chastity, is a modern virtue, appertaining exclusively, as Sir G. Staunton remarks,^^ to civilised life. This is shewn by the ancient religious rites of various nations, by the drawings on the walls of Pompeii, and by the practices of many savages. » We have now seen that actions are regarded by savages, and were probably so regarded by primeval man, as good or bad, solely as they obviously affect the welfare of the tribe,— not that of the si^ecies, nor that of an individual member of the tribe. Tliis conclusion agrees well with the belief that the so-called moral sense is aboriginally derived from the social instincts, for both relate at first exclusively to the community. The chief causes of the low morality of savages, as judged by our standard, are, firstly, the confinement of sympathy to the same tribe. Secondly, powers of reasoning insufficient to recognise the bearing of many virtues, especially of the self-regarding virtues, on the general welfare of the tribe. Savages, for instance, fail to trace the multiplied evils consequent on a want of temperance, chastity, &c. And, thirdly, weak power of self-command ; for this jDower has not been strengthened through long-continued, perhaps inherited, habit, instruction and religion. I have entered into the above details on the immorality of savages,"^ because some authors have recently taken a high view of their moral nature, or have attributed most of their crimes to mistaken benevolence.^^ These authors appear to rest their ^^ Jlr. M'l.ennaa has given ''^ ' Embassy to China,' vol. ii. p. (' Primitive Marriage,' 1865, p. 348. 176) a good collection of facts on ^^ See on this subject copious this head. evidence in Chap. vii. ol' Sir J. Lub- •*' Lecky, 'History of European bock, ' Origin of Civilisation,' 1870. Morals,' vol. i. 1869, p. 109. " For instance Lecky, 'Hist. European Morals,' vol. i. p. 12}-. 1 20 The Descent of Man. Paet T. conclusion on savages possessing those virtues which are ser- viceable, or even necessary, for the existence of the family and of the tribe, —qualities which they undoubtedly do possess, and often in a high degree. Concluding Bemarhs. — It was assumed formerly by philosophers of the derivative*^ school of morals that the foundation of morality lay in a form of Selfishness ; but more recently the " Greatest " happiness principle " has been brought prominently forward. It is, however, more correct to speak of the latter principle as the standard, and not as the motive of conduct. Nevertheless, all the authors whose works I have consulted, with a few excep- tions,*^ write as if there must be a distinct motive for every action, and that this must be associated with some pleasure or displeasure. But man seems often to act impulsively, that is from instinct or long habit, without any consciousness of pleasure, in the same manner as does probably a bee or ant, when it blindly follows its instincts. Under circumstances of extreme peril, as during a fire, when a man endeavours to save a fellow- creature without a moment's hesitation, he can hardly feel pleasure ; and still less has he time to reflect on the dissatisfaction which he might subsequently experience if he did not make the attempt. Should he afterwards reflect over his own conduct, he would feel that there lies within him an impulsive power widely different from a search after pleasure or happiness; and this seems to be the deeply planted social instinct. In the case of the lower animals it seems much more appro- priate to speak of their social instincts, as having been developed •*^ This term is used in an able " noss extra -regarding impulse, di- article in the 'Westminster Review,' " recied towards something that is Oct. 1869, p. 498. For the " Greatest "not pleasure; that in many cases " happiness principle," see J. S. Mill, " the impulse is so far incompatible ' Utilitarianism,' p. 17. " with the self-regarding that the ^2 Mill recognises (' Sj'stem of " two do not easily co-exist in the Logic,' vol. ii., p. 422) in the clearest " same moment of consciousness." manner, that actions mny be per- A dim feeling that our impulses do formed through habit without the not by any means always arise from anticipation of pleasure. Mr. H. any contemporaneous or anticipated Sidgwick also, in his Essay on pleasure, has, I cannot but think. Pleasure and Desire ('The Con- been one chief cause of the accept- temporary Review,' April 1872, p. ance of the intuitive theory of 671), remarks: "To sum up, in morality, and of the rejection of the " contravention of the doctrine that utilitarian or " Greatest happiness '' " our conscious active impulses are theory. With respect to the latter " always directed towards the pro- theory, the standard and the motive " duction of agreeable sensations in of conduct have no doubt often been " ourselves, I would maintain that confused, but they are really in " we find everywhere in conscious- some degree blended. Chap. IV. Mo7'al Sense. 1 2 1 for the general good rather than for the general happiness of the species. The term, general good, may be 'defined as the rearing of the greatest number of individuals in full vigour and health, with all their faculties perfect, under the conditions to which they are subjected. As the social instincts both of man and the lower animals have no doubt been developed by nearly the same steps, it would be advisable, if found practicable, to use the same definition in both cases, and to take as the standard of morality, the general good or welfare of tlie community, rather than the general happiness ; but this definition would perhaps require some limitation on account of political ethics. When a man risks his life to save that of a fellow-creature, it seems also more correct to say that he acts for the general good, rather than for the general happiness of mankind. No doubt the welfare and the happiness of the individual usually coincide ; and a contented, happy tribe will flourish better than one that is discontented and unhappy. We have seen that even at an early period in the history of man, the expressed wishes of the community will have naturally influenced to a large extent the conduct of each member; and as all wish for happiness, the "greatest happiness principle" will have become a most im- portant secondary guide and object ; the social instinct, however, together with sympathy (which leads to our regarding the approbation and disapprobation of others), having served as the primary impulse and guide. Thus the reproach is removed of laying the foundation of the noblest part of our nature in the base principle of selfishness; unless, indeed, the satisfaction which every animal feels, when it follows its proper instincts, and the dissatisfaction felt when prevented, be called selfish. The wishes and opinions of the members of the same community, expressed at first orally, but later by writing also, either form the sole guides of our conduct, or greatly reinforce the social instincts ; such opinions, however, have sometimes a tendency directly opposed to these instincts. This latter fact is well exemplified by the Law of Honour, that is, the law of the opinion of our equals, and not of all our countrymen. The breach of this law, even when the breach is known to be strictly accordant with true morality, has caused many a man more agony than a real crime. We recognise the same influence in the burning sense of shame which most of us have felt, even after the interval of years, when calling to mind some accidental breach of a trifling, though fixed, rule of etiquette. The judgment of the community will generally be guided by some rude experience of what is best in the long run for all the members ; but this judg- ment will not rarely err from ignorance and weak i^owers of 122 The Descent of Man. Part I. reasoning. Hence the strangest cnstoms and superstitions, in complete opposition to* tlie true welfare and happiness of man- kind, have become all-powerful throughout the world. We see this in the horror felt by a Hindoo who breaks his caste, and in many other such cases. It would be difficult to distinguish between the remorse felt by a Hindoo who has yielded to the temptation of eating unclean food, from that felt after committing a theft ; but the former would probably be the more severe. How so many absurd rules of conduct, as well as so many absurd religious beliefs, have originated, we do not know ; nor how it is that they have become, in all quarters of the world, so deeply impressed on the mind of men; but it is worthy of remark that a belief constantly inculcated during the early years of life, whilst the brain is impressible, appears to acquire almost the nature of an instinct ; and the very essence of an instinct is that it is followed independently of reason. Neither can we say why certain admirable Yirtues; such as the love of truth, are much more highly appreciated by some savage tribes than by others ;^^ nor, again, why similar diiferences prevail even amongst highly civihsed nations. Knowing how firmly fixed many strange customs and superstitions have become, we need feel no surprise that the self-regarding virtues, supported as they are by reason, should now appear to us so natural as to be thought innate, although they were not valued by man in his early condition. Notwithstanding many sources of doubt, man can generally and readily distinguish between the higher and lower moral rules. The higher are founded on the social instincts, and relate to the welfare of others. They are supported by the approbation of our fellow-men and by reason. The lower rules, though some of them when implying self-sacrifice hardly deserve to be called lower, relate chiefly to self, and arise from public opinion, ma- tured by experience and cultivation ; for they are not practised by rude tribes. As man advances' in civilisation, and small tribes are united into . larger communities, the simplest reason would tell each individual that he ought to extend his social instincts and sympatlries to all the members of the same nation, though personally unknown to him. This point being once reached, there is only an artificial barrier to prevent his sympathies extending to the men of all nations and races. If, indeed, such men are separated from him by great differences in appearance *^ Good instances are given by in his 'Contributions to the Theory Mr. Wallace in 'Scientific Opinion/ of Natural Selection,' 1870, p. 353. Sept. 15, 1869 ; and more fully Chap. IV. Moral Sense. 123 or habits, experience ■unfortunately shews us how long it is, before we look at them as our fellow-creatures. Sympathy beyond the confines of man, that is, humanity to the lower animals, seems to be one of the latest moral acquisitions. It is apparently unfelt by savages, except towards their pets. How little the old Romans knew of it is shewn by their abhorrent gladiatorial exhibitions. The very idea of humanity, as tar as I could observe, w^as new to most of the Gauchos of the Pampas. This virtue, one of the noblest with which man is endowed, seems to arise incidentally from our sympathies becoming more tender and more widely diffused, until they are extended to all sentient beings. As soon as this virtue is honoured and practised by some few men, it spreads through instruction and example to the young, and eventually becomes incorporated in public opinion . The highest possible stage in moral culture is when we re- cognise that w^c ought to control our thoughts, and " not even in " inmost thought to think again the sins that made the past so " pleasant to us." " ' Whatever makes any bad action familiar to the mind, renders its performance by so much the easier. As Marcus Aurelius long ago said, "Such as are thy habitual " thoughts, such also will be the character of thy mind ; for the " soul is dyed by the thoughts." ^^ Our great philosopher, Herbert Spencer, has recently explained his views on the moral sense. He says,'*'^ " I believe that the " experiences of utility organised and consolidated through all " past generations of the human race, have been producing. " corresponding modifications, which, by continued transmission " and accumulation, have become in us certain faculties of " moral intuition— certain emotions responding to right and " wrong conduct, w^hich have no apparent basis in the individual " experiences of utility." There is not the least inherent improbability, as it seems to me, in virtuous tendencies being more or less strongly inherited; for, not to mention the various dispositions and habits transmitted by many of our domestic animals to their offspring, I have heard of authentic cases in which a desire to steal and a tendency to lie appeared to run in families of the upper ranks ; and as stealing is a rare crime in the wealthy classes, we can hardly account by accidental coinci- dence for the tendency occurring in two or three members of ^^ Tennyson, 'Idylls of the King,* Aurelius was born a.d. 121. p. 244. ••« Letter to Mr. Mill in B;tiu's ** ' The Thoughts of the Emperor ' Mental and Moral Science,' 18(J8, M. Aurelius Antoninus,' Eng. trans- p. 722. lat., 2ud edit., 1869, p. 112. Marcus 124 The Descejtt of Man. Paet I. the same family. If bad tendencies are transmitted, it is pro- bable that good ones are likewise transmitted. That the state of the body by affecting the brain, has great influence on the moral tendencies is known to most of those who have suffered from chronic derangements of the digestion or liver. The same fact is likewise shewn by the " perversion or destruction of the " moral sense being often one of the earliest symptoms of mental "derangement;"^^ and insanity is notoriously often inherited. Except through the principle of the transmission of moral ten- dencies, we cannot understand the differences believed to exist in this respect between the various races of mankind. Even the partial transmission of virtuous tendencies would be an immense assistance to the primary impulse derived directly and indirectly from the social instincts. Admitting for a moment that virtuous tendencies are inherited, it appears probable, at least in such cases as chastity, temperance, humanity to animals, &c., that they become first impressed on the mental organization through habit, instruction and example, continued during several generations in the same family, and in a quite subordinate degree, or not at all, by the individuals possessing such virtues having succeeded best in the struggle for life. My chief source of doubt with respect to any such inheritance, is that senseless customs, superstitions, and tastes, such as the horror of a Hindoo for unclean food, ought on the same principle to be transmitted. I have not met with any evidence in support of the transmission of superstitious customs or senseless habits, although in itself it is perhaps not less probable than that animals should acquire inherited tastes for certain kinds of food or fear of certain foes. Finally the social instincts, Avhich no doubt were acquired by man as by the lower a-nimals for the good of the community, will from the first have given to him some wish to aid his fellows, some feeling of sympathy, and have compelled him to regard their approbation and disapprobation. Such impulses will have served him at a very early period as a rude rule of right and wrong. But as man gradually advanced in intellectual power, and was enabled to trace the more remote consequences of his actions ; as he acquired sufficient knowledge to reject baneful customs and superstitions; as he regarded more and more, not only the welfare, but the happiness of his fellow-men ; as from habit, following on beneficial experience, instruction and example, his sympathies became more tender and widely diffused, extending to men of all races, to the imbecile, maimed, *^ Maudsley, 'Body and Mind,' 1870, p. 60. Chap. IV. Summary. 125 and otlier useless members of society, and finally to the lower animals,— so would the standard of his morality rise higher and higher. And it is admitted by moralists of the derivative school and by some intuitionists, that the standard of morality has risen since an early period in the history of man/** As a struggle may sometimes be seen going on between the various instincts of the lower animals, it is not surprising that there should be a struggle in man between his social instincts, with their derived virtues, and his lower, though momentarily stronger impulses or desires. This, as Mr. Galton*^ has remarked, is all the less surprising, as man has emerged from a state of barbarism within a comparatively recent period. After having yielded to some temptation we feel a sense of dissatisfaction, shame, repentance, or remorse, analogous to the feelings caused by other iwwcrful instincts or desires, when left unsatisfied or baulked. We compare the weakened impression of a past temptation with the ever present social instincts, or with habits, gained in early youth and strengthened during our whole lives, until they have become almost as strong as instincts. If with the temptation still before us we do not yield, it is because either the social instinct or some custom is at the moment predominant, or because we have learnt that it will appear to us hereafter the stronger, when comj)ared with the weakened im- pression of the temptation , and we realise that its violation would cause us suffering. Looking to future generations, there is no cause to fear that the social instincts will grow weaker, and we may expect that virtuous habits will grow stronger, becoming perhaps fixed by inheritance. In this case the struggle between our higher and lower impulses will be less severe, and virtue will be triumphant. Summary of the last two Chapters.— Thci'O can be no doubt that the difference between the mind of the lowest man and that of the highest animal is immense. An anthropomorphous ape, if he could take a dispassionate view of his own case, would admit that though he could form an artful plan to plunder a garden — though he could use stones for fighting or for breaking open nuts, yet that the thought of fashioning a stone into a tool was ■•' A writer in the 'North British coincide therein. Review' (July 1869, p. o.'jI), well *" See his remarkable work on capable of forming a sound judg- ' Hereditary Genius,* 18G9, p. 349. ment, expresses himself strongly in The Duke of Argyll (' Primeval favour of this conclusion. Mr. Man,' 1809, p. 188) has some good Lecky ('Hist, of Morals,' vol. i. p. remarks on the contest in man's 143) seems to a certain extent to nature between right and wrong. 1 26 The Descent of Man. Part I. quite beyond liis scope. Still less, as he would admit, could lie follow out a train of metaphysical reasoning, or solve a mathe- matical problem, or reflect on God, or admire a grand natural scene. Some apes, however, would probably declare that they could and did admire the beauty of the coloured skin and fur of their partners in marriage. They would admit, that though they could make other apes understand by cries some of their per- ceptions and simpler wants, the notion of expressing definite ideas by definite sounds had never crossed theii' minds. They might insist that they were ready to aid their fellow-apes of the same troop in many ways, to risk their lives for them, and to take charge of their orphans ; but they would be forced to acknow- ledge that disinterested love for all living creatures, the most noble attribute of man, was quite beyond their comprehension. Nevertheless the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind. We have seen that the senses and intuitions, the various emotions and faculties, such as love, memory, attention, curiosity, imitation, reason, &c., of w^hich man boasts, may be found in an incipient, or even sometimes in a well- developed condition, in the lower animals. They are also capable of some inherited improvement, as we see in the domestic dog compared with the wolf or jackal. If it could be proved that certain high mental powers, such as the formation of general concepts, self-con- sciousness, &c., were absolutely peculiar to man, which seems extremely doubtful, it is not improbable that these qualities are merely the incidental results of other highly-advanced intel- lectual faculties; and these again mainly the result of the continued use of a perfect language. At what age does the new-born infant possess the power of abstraction, or become self-conscious, and reflect on its own existence ? We cannot answer ; nor can we answer in regard to the ascending organic scale. The half-art, half-instinct of language still bears the stamp of its gradual evolution. The ennobhng belief in God is not universal with man; and the belief in spiritual agencies naturally follows from other mental powers. The moral sense perhaps affords the best and highest distinction between man and the lower animals ; but I need say nothing on this head, as I have so lately endeavoured to shew that the social instincts, — the prime principle of man's moral constitution ^" — with the aid of active intellectual powers and the effects of habit, naturally lead to the golden rule, " As ye would that men should do to you, do ye to them likewise ;'' and this lies at the foundation of morality. so ' The Tlioughts of Marcus Aurelius,' &c., p. 139. TiiAP. V. Ijitellcctnal Faculties. 1 27 In the next chapter I shall make some few remarks on the probable steps and means by which the several mental and moral faculties of man have been gradually evolved. That such evolu- tion is at least possible, ought not to be denied, for we daily sec these faculties developing in every infant ; and we may trace a perfect gradation from tlie mind of an utter idiot, lower than that of an animal low in the scale, to the mind of a Newton. CHAPTER V. On the Development of the Intellectual and Moral Faculties during Primeval and Civilised Times. Ailvanceniont of the intellectual powers through natural selection — Importance of imitation — Social and moral faculties — Their develop- ment within the limits of the same tribe — Natural selection as affecting civilised nations — Evidence that civilised nations were once barbarous. The subjects to be discussed in this chapter are of the highest interest, but are treated by me in an imperfect and fragmentary manner. Mr. Wallace, in an admirable paper before referred to,' argues that man, after he had partially acquired those intel- tectual and moral faculties which distinguish him from the lower animals, would have been but little liable to bodily modifications through natural selection or any other means. For man is enabled through his mental faculties '' to keep with " an unchanged body in harmony with the changing universe." He has great power of adapting his habits to new conditions of life. He invents weapons, tools, and various stratagems to procure food and to defend himself. When he migrates into a colder climate he nses clothes, builds sheds, and makes fires ; and by the aid of fire cooks food otherwise indigestible. Ho aids his fellow-men in many ways, and anticipates future events Even at a remote period he practised some division of labour. The lower animals, on the other hand, must have their bodily structure modified in order to survive under greatly changed conditions. They must be rendered stronger, or acquire more effective teeth or claws, for defence against new enemies; or they must be reduced in size, so as to escape detection and danger. When they migrate into a colder climate, they must become clothed with thicker fur, or have their constitutions altered. If they fail to be thus modified, they will cease to exist • ' Antliropological Review,' ^'^ay 13G4, p. clviii. 128 The Descent of Man. Part I. The case, however, is widely different, as Mr. Wallace has with justice inssted, in relation to the intellectnal and moral faculties of man. These faculties are variable; and we have every reason to believe that the variations tend to be inherited. Therefore, if they were formerly of high importance to primeval man and to his ape-like progenitors, they would have been perfected or advanced through natural selection. Of the high importance of the intellectual faculties there can be no doubt, for man mainly owes to them his predominant position in the world. We can see, that in the rudest state of society, the individuals who were the most sagacious, who invented and used the best weapons or traps, and who were best able to defend themselves, would rear the gi-eatest number of offspring. The tribes, which included the largest number of men thus endowed, would increase in number and supplant other tribes. Numbers depend primarily on the means of subsistence, and this depends partly on the physical nature of the country, but in a much higher degree on the arts which are there practised. As a tribe increases and is victorious, it is often still further increased by the ab- sorption of other tribes.^ The stature and strength of the men of a tribe are likewise of some importance for its success, and these depend in part on the nature and amount of the food which can be obtained. In Europe the men of the Bronze period were supplanted by a race more powerful, and, judging from their sword-handles, with larger hands f but their success was pro- bably still more due to their superiority in the arts. All that we Imow about savages, or may infer from their traditions and from old monuments, the history of which is quite forgotten by the present inhabitants, shew that from the remotest times successful tribes have supplanted other tribes. Eelics of extinct or forgotten tribes have been discovered throughout the civilised regions of the earth, on the wild plains of America, and on the isolated islands in the Pacific Ocean. At the i^resent day civilised nations are everywhere supplanting barbarous nations, excepting where the climate opposes a deadly barrier; and they succeed mainly, though not exclusively, through their arts, which are the products of the intellect. It is, therefore, highly probal^le that with mankind the intellectual faculties have been mainly and gradually perfected through natural selection; and this con- clusion is sufficient for our purpose. Undoubtedly it would be interesting to trace the development of each separate faculty 2 After a time the members or 1861, p. 131), that they are the co- tribes which are absorbed into descendants of the same ancestors, another tribe assume, as Sir Henry ^ Morlot, ' Soc. Vaud. Sc. Nat.' Maine remarks ('Ancient Law,' 1860, p. 294. Chap. V. Moral Faculties. 129 from the state in which it exists in the lower animals to that in which it exists in man ; but neither my ability nor knowledge permits the attempt. It deserves notice that, as soon as the progenitors of man became social (and this probably occurred at a very early period), the principle of imitation, and reason, and experience would have increased, and much modified the intellectual powers in a way, of which we see only traces in the lower animals. Apes are much given to imitation, as are the lowest savages; and the simple fact previously referred to, that after a time no animal can be caught in the same place by the same sort of trap, shews that animals learn by experience, and imitate the caution of others. Now, if some one man in a tribe, more sagacious than the others, invented a new snare or weapon, or other means of attack or defence, the plainest self-interest, without the assistance of much reasoning power, would prompt the other members to imitate him ; and all would thus profit. The habitual practice of each new art must likewise in some slight degree strengthen the intellect. If the new invention were an important one, the tribe would increase in number, spread, and sujDplant other tribes. In a tribe thus rendered more numerous there would always be a rather greater chance of the birth of other superior and inventive members. If such men left children to inherit their mental superiority, the chance of the birth of still more ingenious members would be somewhat better, and in a very small tribe decidedly better. Even if they left no children, the tribe would still include their blood- relations ; and it has been ascertained by agriculturists * that by preserving and breeding from the family of an animal, which when slaughtered was found to be valuable, the desired character has been obtained. Turning now to the social and moral faculties. In order that primeval men, or the ape-like i)regenitors of man, should become social, they must have acquired the same instinctive feelings, which impel other animals to live in a body ; and they no doubt exhibited the same general disposition. They would have felt uneasy when separated from their comrades, for whom they would have felt some degree of love ; they would have warned each other of danger, and have given mutual aid in attack or defence. All this implies some degree of sympathy, fidelity, and courage. Such social qualities, the paramount importance of which to the lower animals is disputed by no one, were no doubt * I have given iustanccs in my * Variation of Animals ujiJer Domestica- tion,' vol. ii. p. 196. 7 1 30 The Descent of Man. Part 1. acquired by the progenitors of man in a similar manner^ namely, through natural selection, aided by inherited habit. When two tribes of primeval man, living in the same country, came into competition, if (other circumstances being equal) the one tribe included a gi-eat number of courageous, sjTnpathetic and faithful members, who were always ready to warn each other of danger, to aid and defend each other, this tribe would succeed better and conquer the other. Let it be borne in mind how all-important in the never-ceasing wars of savages, fidehty and courage must be. The advantage which disciplined soldiers have over undis- ciplined hordes follows chiefly from the confidence which each man feels in his comrades. Obedience, as IMr. Bagehot has well shewTi,^ is of the highest value, for any form of government is better than none. Selfish and contentious people will not cohere, and without coherence nothing can be effected. A ti*ibe rich in the above qualities would spread and be victorious over other tribes : but in the course of time it would, judging from all past history, be in its turn overcome by some other tribe still more highly endowed. Thus the social and moral qualities would tend slowly to advance and be diffused throughout the world. But it may be asked, how within the limits of the same tribe did a large number of members first become endowed with these social and moral qualities, and how was the standard of ex- cellence raised ? It is extremely doubtful whether the offspring of the more sympathetic and benevolent parents, or of those who were the most faithful to their comrades, would be reared in greater numbers than the children of selfish and treacherous parents belonging to the same tribe. He who was ready to sacrifice his life, as many a savage has been, rather than betray his comrades, would often leave no offspring to inherit his noble nature. The bravest men, who were always willing to come to the front in war, and who freely risked their lives for others, would on an average perish in larger numbers than other men. Therefore it hardly seems probable, that the number of men gifted with such virtues, or that the standard of their excellence, could be increased through natural selection, that is, by the survival of the fittest ; for we are not here speaking of one tribe being victorious over another. Although the circumstances, leading to an increase in the number of those thus endowed within the same tribe, are too complex to be clearly followed out, we can trace some of the probable steps. In the first place, as the reasoning powers and * See a remarkable series of arti- April 1, 1868 ; July 1, 1869, since cles on ' Physics and Politics ' in the separately published. ' Fortnightly Review,' Nov. 1867 ; Chap. V. Moral Facilities. 1 3 1 foresight of the members became improved, each man would' soon learn that if ho aided his fellow-men, he would commonly receive aid in return. From this low motive he might acquire the habit of aiding his fellows ; and the habit of performing benevolent actions certainly strengthens the feeling of sympathy which gives the first impulse to benevolent actions. Habits, moreover, followed during many generations probably tend to be inherited. But another and much more powerful stimulus to the de- velopment of the social virtues, is afforded by the praise and the blame of our fellow-men. To the instinct of sympathy, as we have already seen, it is primarily due, that we habitually bestow both praise and blame on others, whilst we love the former and dread the latter when applied to ourselves ; and this instinct no doubt was originally acquired, like all the other social instincts, through natural selection. At how early a period the progenitors of man in the course of their development, became capable of feehngand being impelled by, the praise or blame of their fellow-creatures, we caijnot of course say. But it appears that even dogs appre- ciate encouragement, praise, and blame. The rudest savages feel the sentiment of glory, as they clearly show by preserving the trophies of their prowess, by their habit of excessive boasting, and even by the extreme care which they take of their per- sonal appearance and decorations ; for unless they regarded the opinion of their comrades, such habits would be senseless. They certainly feel shame at the breach of some of their lesser rules, and apparently remorse, as shewn by the case of the Australian who grew thin and could not rest from having delayed to murder some other woman, so as to propitiate his dead wife's spirit. Though I have not met with any other recorded case, it is scarcely credible that a savage, who will sacrifice his life rather than betray his tribe, or one who will deliver himself up as a prisoner rather than break his parole,*^ would not feel remorse in his inmost soul, if he had failed in a duty, which he held sacred. » We may therefore conclude that primeval man, at a very remote period, was influenced by the praise and blame of his fellows. It is obvious, that the members of the same tribe would approve of conduct which appeared to them to be for the general good, and would reprobate that which appeared evil. To do good unto others — to do unto others as ye would they should do unto you— is the foundation-stone of morality. It is, therefore, hardly possible to exaggerate the importance during rude times ^ Mr. Wallace gives cases in of Natural Seleotioa,' 1870, p. bla 'Contributions to the Theory 354. 132 The Descent of Man. Part 1. of the loYe of praise and the dread of blame. A man who was not impelled by any deep, instinctive feeling, to sacrifice his life for the good of others, yet was roused to such actions by a sense of glory, would by his example excite the same wish for glory in other men, and would strengthen by exercise the noble feeling of admiration. He might thus do far more good to his tribe than by begetting offspring with a tendency to inherit his own high character. With increased experience and reason, man perceives the more remote consequences of his actions, and the self-regarding virtues, such as temperance, chastity, &c., which during early times are, as we have before seen, utterly disregarded, come to be highly esteemed or even held sacred. I need not, however, repeat what I have said on this head in the fourth chapter. Ultimately our moral sense or conscience becomes a highly complex sentiment— originating in the social instincts, largely guided by the approbation of our fellow-men, ruled by reason, self-interest, and in later times by deep religious feelings, and confirmed by instruction and habit. ' * It must not be forgotten that although a high standard of morality gives but a slight or no advantage to each individual man and his children over the other men of the same tribe, yet that an increase in the number of well-endowed men and an advancement iii the standard of morality will certainly give an immense advantage to one tribe over another. A tribe including many members who, from possessing in a high degTee the spmt of patriotism, fidelity, obedience, courage, and sympathy, were always ready to aid one another, and to sacrifice themselves for the common good, would be victorious over most other tribes ; and this would be natural selection. At all times throughout the world tribes have supplanted other tribes ; and as morahty is one important element in their success, the standard of morality and the number of well- en do wed men will thus every- where tend to rise and increase. It is, however, very difficult to form any judgment why one particular tribe and not another has been successful and has risen in the scale of civilisation. Many savages are in the same condition as when first discovered several centuries ago. As Mr. Bagehot has remarked, we are apt to look at progress as normal in human society ; but history refutes this. The ancients did not even entertain the idea, nor do the Oriental nations at the present day. According to another high authority. Sir Henry Maine,^ " the greatest part of mankind has never shewn a ' 'Ancient Law,' 1861, p. 22. nightly Review,' April 1, 1S68, p. For Mr. Bagehot's remarks, ' Fort- 452. Chap. V. Civilised Nations. 00 " particlo of desire that its civil institutions should be iui- " proved." Progress seems to depend on many concurrent favourable conditions, far too complex to be followed out. But it has often been remarked, that a cool climate, from leading to industry and to the various arts, has been highly favourable thereto. The Esquimaux, pressed by hard necessity, have succeeded in many ingenious inventions, but their climate has been too severe for continued progress. Nomadic habits, whether over wide plains, or through the dense forests of the tropics, or along the shores of the sea, have in every case been highly detrimental. "Whilst observing the barbarous inhabitants of Tierra del Fuego, it struck me .that the possession of some property, a fixed abode, and the union of many families under a chief, were the indispensable requisites for civilisation. Such habits almost necessitate the cultivation of the ground ; and the first steps in cultivation would j^robably result, as I have else- where shewu,^ from some such accident as the seeds of a fruit- tree falling on a heap of refuse, and producing an unusually fine variety. The problem, however, of the first advance of savages towards civilisation is at present much too difficult to be solved. Natural Selection as affecting Civilised Nations. — I have hitherto only considered the advancement of man from a semi-human condition to that of the modern savage. But some remarks on the action of natural selection on civilised nations may be worth adding. This subject has been ably discussed by Mr. W. E. Greg,^ and previously by Mr. Wallace and Mr. Galton.^** Most of my remarks are taken from these three authors. With savages, the weak in body or mind are soon eliminated ; and those that survive commonly exhibit a vigorous state of health. We civilised men, on the other hand, do our utmost to check the process of elimination ; we build asylums for the imbecile, the maimed, and the sick ; we institute poor-laws ; and our medical " 'The Variation of Animals and 1869, and by Mr. E. Ray Lankester Plants under Domestication,' vol. i. in his 'Comparative Longevitv,' p. 309. 1870, p. 128. Similar views ap- * 'Eraser's Magazine,' Sept. 1868, peared previously in the 'Austra- p. 353. This article seems to have lasian,' July* 13, 1867. I have struck many persons, and has given borrowed ideas from several of these rise to two remarkable essays and a writers. rejoinder in the ' Spectator,' Oct. ^'^ For Mr. Wallace, see ' Anthro- 3rd and 17th, 1868. It has also polog. Review,' as before cited. Mr. been discussed in the 'Q. Journal of Galton in ' Macmillan's Magazine,' Science,' 1869, p. 152, and by Mr. Aug. 1865, p. 318 ; also his great Lawson Tait in the 'Dublin Q. work, ' Hereditary Genius,' 1870. Journal of Medical Science,' Feb. 1 34 The Descent of Man. Part I. men exert their utmost skill to save the Kfe of every one to the last moment. There is reason to belieye that vaccination has preserved thousands, who from a weak constitution would formerly have succumbed to small-pox. Thus the weak members of civilised societies propagate their kind. No one who has attended to the breeding of domestic animals will doubt that this must be highly injurious to the race of man. It is surprising how soon a want of care, or care wrongly directed, leads to the degeneration of a domestic race ; but excepting in the case of man himself, hardly any one is so ignorant as to allow his worst animals to breed. The aid which we feel impelled to give to the helpless is mainly an incidental result of the instinct of sympathy, which was originally acquired as pai*t of the social instincts, but sub- sequently rendered, in the manner previously indicated, more tender and more widely diifused. Nor could we check our sympathy, even at the urging of hard reason, without deteriora- tion in the noblest part of our nature. The surgeon may harden himself whilst performing an operation, for he knows that he is acting for the good of his patient ; but if we were intentionally to neglect the weak and helpless, it could only be for a con- tingent benefit, with an overwhelming present evil. We must therefore bear the undoubtedly bad eflfects of the weak surviving and propagating their kind ; but there appears to be at least one check in steady action, namely that the weaker and inferior members of society do not marry so freely as the sound ; and this check might be indefinitely increased by the weak in body or mind refraining from marriage, though this is more to be hoped for than expected. In every country in which a large standing army is kept up, the finest young men are taken by the conscription or are enlisted. They are thus exposed to early death during war, are often tempted into vice, and are prevented from marrying during the prime of life. On the other hand the shorter and feebler men, with poor constitutions, are left at home, and consequently have a much better chance of marrying and jDropagating their kind.^^ Man accumulates property and bequeaths it to his children, so that the children of the rich have an advantage over the poor in the race for success, independently of bodily or mental su- periority. On the other hand, the children of parents who are short-lived, and are therefore on an average deficient in health and vigour, come into their property sooner than other children, " Prof. H, Fick (' Einfluss der on this head, and on other such Naturwissenschaft auf das Eecht,' points. June, 1872) has some good remarks Chap. V. Civilised Nations. 1 3 5 and will be likely to marry earlier, and leave a larger number of offspring to inherit their inferior constitutions. But the in- heritance of property by itself is very far from an evil ; for without the accumulation of capital the arts could not progress ; and it is chiefly through their power that the civilised races have extended, and arc now everywhere extending their range, so as to take the place of the lower races. Nor does the moderate accumulation of wealth interfere with the process of selection. When a poor man becomes moderately rich, his children enter trades or professions in which there is struggle enough, so that the able in body and mind succeed best. The presence of a body of well-instructed men, who have not to labour for their daily bread, is important to a degree which cannot be over-estimated ; as all high intellectual work is carried on by them, and on such work, material jirogress of all kinds mainly depends, not to mention other and higher advantages. No doubt wealth when very gi-eat tends to convert men into useless drones, but their number is never large; and some degree of elimination here occurs, for we daily see rich men, who happen to be fools or profligate, squandering away their wealth. Primogeniture with entailed estates is a more direct evil, though it may formerly have been a great advantage by the creation of a dominant class, and any government is better than none. Most eldest sons, though they may be weak in body or mind, marry, whilst the younger sons, however superior in these respects, do not so generally marry. Nor can worth- less eldest sons with entailed estates squander their wealth. But here, as elsewhere, the relations of civilised life are so complex that some compensatory checks intervene. The men who are rich through primogeniture are able to select genera- tion after generation the more beautiful and charming women ; and these must generally be healthy in body and active in mind. The evil consequences, such as they may be, of the continued preservation of the same line of descent, without any selection, are checked by men of rank always wishing to increase their wealth and power; and this they effect by marrying heiresses. But the daughters of parents who have produced single children, are themselves, as Mr. Galton^^ has shewn, apt to be sterile ; and thus noble families are continually cut off in the direct line, and their wealth flows into some side channel ; but unfortunately this channel is not determined by superiority of any kind. Although civilisation thus checks in many ways the action of >2 'Hereditary Genius,' 1870, pp. 132-140. 136 The Desce7it of Man. Part I. natural selection, it apparently favours the better development of the body, by means of good food and the freedom from occa- sional hardships. This may be inferred from civilised men having been found, wherever compared, to be physically stronger than savages.'^ They appear also to have equal powers of endurance, as has been proved in many adventurous ex- peditions. Even the great luxury of the rich can be but little detrimental ; for the expectation of life of our aristocracy, at all ages and of both sexes, is very httle inferior to that of healthy English lives in the lower classes.^* We will now look to the intellectual faculties. If in each grade of society the members were divided into two equal bodies, the one including the intellectually superior and the other the inferior, there can be little doubt that the former would succeed best in all occupations, and rear a greater number of children. Even in the lowest walks of life, skill and ability must be of some advantage; though in many occupations, owing to the great division of labour, a very small one. Hence in civilised nations there will be some tendency to an increase both in the number and in the standard of the intellectually able. But I do not wish to assert that this tendency may not be more than counterbalanced in other ways, as by the multiplica- tion of the reckless and improvident ; but even to such as these, ability must be some advantage. It has often been objected to views like the foregoing, that the most eminent men who have ever lived have left no offspring to inherit their great intellect. Mr. Galton says,^^ " I regret I am " unable to solve the simple question whether, and how far, '' men and women who are prodigies of genius are infertile. I " have, however, shewn that men of eminence are by no means " so." Great lawgivers, the founders of beneficent rehgions, great philosophers and discoverers in science, aid the progress of mankind in a far higher degree by their works than by leaving a numerous progeny. In the case of corporeal structures, it is the selection of the slightly better-endowed and the elimination of the slightly less well-endowed individuals, and not the pre- servation of strongly-marked and rare anomalies, that leads to the advancement of a species.^'' So it will be with the intellectual faculties, since the somewhat abler men in each grade of society '^ Quatrefages, 'Revue des Cours 1870, p. 115. Scientifiques,' 1867-68, p. 659. i^ < Hereditary Genius,' 1870, p. ^■^ See the fifth and sixth columns, 330. compiled from good authorities, in ^*^ ' Origin of Species ' (fifth edi- the table given in Mr. E. R, Lan- tion, 1869), p. lO-l. kester's ' Comparative Longevity,' Chap. V. • Civilised Nations. ■ 137 succeed rather better than the less able, and consequently increase in number, if not otherwise prevented. When in any nation the standard of intellect and the number of intel- lectual men have increased, we may expect from the law of the deviation from an average, that prodigies of genius will, as shewn by Mr. Galton, appear somew^hat more frequently than before. In regard to the moral qualities, some elimination of the worst dispositions is always in progress even in the most civilised nations. Malefactors are executed, or imprisoned for long periods, so that they cannot freely transmit their bad qualities. Melancholic and insane persons are confined, or commit suicide. Violent and quarrelsome men often come to a bloody end. The restless who will not follow any steady occupation— and this relic of barbarism is a great check to civilisation ^^ — emigrate to newly-settled countries, where they prove useful pioneers. In- temperance is so highly destructive, that the expectation of life of the intemperate, at the age of thirty for instance, is only 13-8 years ; whilst for the rural labourers of England at the same age it is 40*59 years.^^ Profligate women bear few children, and profligate men rarely marry ; both suifer from disease. In the breeding of domestic animals, the elimination of those individuals, though few in number, which are in any marked manner inferior, is by no means an unimportant element towards success. This especially holds good with injurious characters which tend to reappear through reversion, such as blackness in sheep; and with mankind some of the worst dispositions, W'hich occasionally without any assignable cause make their appearance in families, may perhaps be reversions to a savage state, from which we are not removed by very many generations. This view seems indeed recognised in the common expression that such men are the black sheep of the family. With civilised nations, as far as an advanced standard of morality, and an increased number of fairly good men are con- cerned, natural selection apparently effects but little ; though the fundamental social instincts w^ere originally thus gained. But I have already said enough, whilst treating of the lower races, on the causes which lead to the advance of morality, namely, the approbation of our fellows-men — the strengthening ^^ 'Hereditary Genius,' 1870, p. Xeison's * Vital Statistics.' In re- 347. gard to profligacy, see Dr. Farr, " E. Ray Lankester, ' Compara- 'Influence of Marriage on Mor- tive Longevity,' 1870, p. 115, Tiie tality,' 'Nat. Assoc, for the Promo- table of the intemperate is from tion of Social Science,' 1858. 138 The Descent of Man. Part T. of our sympathies by habit — example and imitation — reason — experience, and even self-interest — instruction during youth, and rehgious feelings. A most important obstacle in civilised conntries to an increase in the number of men of a superior class has been strongly insisted on by Mr. Greg and Mr. Galton/^ namely, the fact that the very poor and reckless, who are often degraded by vice, almost invari- ably marry early, whilst the careful and frugal, who are generally otherwise virtuous, marry late in life, so that they may be able to support themselves and their children in comfort. Those who marry early produce within a given period not only a greater number of generations, but, as shewn by Dr. Duncan,^*^ they pro- duce many more children. The children, moreover, that are born by mothers during the prime of life are heavier and larger, and therefore probably more vigorous, than those born at other periods. Thus the reckless, degraded, and often vicious members of society, tend to increase at a quicker rate than the provident and generally virtuous members. Or as Mr. Greg puts the case : " The careless, squalid, unaspiring Irishman multiplies like " rabbits : the frugal, foreseeing, self-respecting, ambitious Scot, " stern in his morality, spiiitual in his faith, sagacious and dis- " ciplined in his intelligence, passes his best years in struggle " and in celibacy, marries late, and leaves few behind him. " Given a land originally peopled by a thousand Saxons and a " thousand Celts — and in a dozen generations five-sixths of the " population would be Celts, but five-sixths of the property, of " the power, of the intellect, would belong to the one-sixth of '' Saxons that remained. In the eternal ' struggle for existence,' " it would be the inferior and le»8 favoured race that had pre- " vailed— and prevailed by virtue not of its good qualities but of " its faults." There are, however, some checks to this downward tendency. We have seen that the intemj)erate suffer from a high rate of mortality, and the extremely profligate leave few offspring. The poorest classes crowd into towns, and it has been proved by Dr. Stark from the statistics of ten years in Scotland,^^ that at all '^ * Fraser's Magazine,' Sept. title of ' Fecundity, Fertility, and 1868, p. 353. 'Macmillan's Maga- Sterility,' 1871. See, also, Mr. zine, Aug. 1865, p. 318. The Rev. Galton, 'Hereditary Genius,' pp. F. W. Farrar (' Fraser's Mag.' Aug. 352-357, for observations to the 1870, p. 264) takes a different view. above effect. 2*^ ' On the Laws of the Fertility 2' ' Tenth Annual Report of of Women,' in ' Transact. Royal Births, Deaths, &c., in Scotland,' Soc' Edinburgh, vol. xxiv. p. 287 ; 1867, p. xxix. now published separately under the (jiiAP. V. Civilised Nations. 1 39 ages the death-rate is higher in towns tlian in rural districts, " and during the first five years of life the town death-rate is *' almost exactly double that of the rural districts." As these re- tui-ns include both the rich and the poor, no doubt more than twice the number of births would be requisite to keep up the number of the very poor inhabitants in the towns, relatively to those in the country. With women, marriage at too early an age is highly injurious ; for it has been found in France that, " twice as many wives under twenty die in the year, as died out *' of the same number of the unmarried." The mortality, also, of husbands under twenty is " excessively high," ^^ but what the cause of this may be, seems doubtful. Lastly, if the men who prudently delay marrying until they can bring up their families in comfort, were to select, as they often do, women in the prime of life, the rate of increase in the better class w^ould be only slightly lessened. It was established from an enormous body of statistics, taken during 1853, that the unmarried men throughout France, between the ages of twenty and eighty, die in a much larger proportion than the married : for instance, out of every 1000 unmarried men, between the ages of twenty and thirty, 11-3 annually died, whilst of the married only 6'5 died.^^ A similar law was proved to hold good, during the years 18G3 and 1864, with the entire population above the age of twenty in Scotland : for instance, out of every 1000 unmarried men, between the ages of twenty and thirty, 14-97 annually died, whilst of the married only 7-21: died, that is less than half.^* Dr. Stark remarks on this, " Bachelorhood is more destructive to life than the most "unwholesome trades, or than residence in an unwholesome " house or district where there has never been the most distant " attempt at sanitary improvement." He considers that the lessened mortality is the direct result of " marriage, and the " more regular domestic habits which attend that state." He admits, however, that the intemperate, profligate, and criminal classes, whose duration of life is low, do not commonly marry ; and it must likewise be admitted that men with a weak constitu- ^ These quotations are taken from the same striking paper, from our highest authority on such -* 1 have taken the mean of the questions, namely, Dr. Farr, in his quinquennial means, given in ' The paper 'On the Influence of Mar- Tenth Annual Report of Births, riage on the Mortality of the French Deaths, &c., in Scotland,' 18G7. People,' read before the Nat. Assoc. The quotation from Dr. Stark is for the Promotion of Social Science, copied from an article in the ' Daily 1858. News,' Oct. 17th, 18G8, which Dr. 23 Dr. Farr, ibid. The quota- Farr considers very carefully writ- tioas given below are extracted ten. 140 The Descent of Man. Part I. tion, ill health, or any great infirmity in body or mind, will often not wish to marry, or will be rejected. L)r. Stark seems to have come to the conclusion that marriage in itself is a main cause of prolonged life, from finding that aged married men still have a considerable advantage in this respect over the unmarried of the same advanced age ; but every one must have known instances of men, who with weak health during youth did not marry, and yet have survived to old age, though remaining weak, and there- ' fore always with a lessened chance of life or of marrying. There is another remarkable circumstance which seems to support Dr. Stark's conclusion, namely, that widows and widowers in France suffer in comparison with the married a very heavy rate of mor- tality ; but Dr. Farr attributes this to the poverty and evil habits consequent on the disruption of the family, and to grief. On the whole we may conclude with Dr. Farr that the lesser mortahty of married than of unmarried men, which seems to be a general law, "is mainly due to the constant elimination of imperfect " types, and to the skilful selection of the finest individuals out " of each successive generation ;" the selection relating only to the marriage state, and acting on all corporeal, intellectual, and moral qualities.^^ We may, therefore, infer that sound and good men who out of prudence remain for a time unmarried, do not suffer a high rate of mortality. If the various checks specified in the two last paragraphs, and perhaps others as yet unknown, do not prevent the reckless, the vicious and otherwise inferior members of society from increas- ing at a quicker rate than the better class of men, the nation will retrograde, as has too often occurred in the history of the world. We must remember that progress is no invariable rule. It is very diflScult to say why one civilised nation rises, becomes more l^owerful, and sjDreads more widely, than another ; or why the same nation progresses more quickly at one time than at another. We can only say that it depends on an increase in the actual number of the population, on the number of the men endowed with high intellectual and moral faculties, as well as on their standard of excellence. Corporeal structure appears to have little influence, except so far as vigour of body leads to vigour of mind. It has been urged by several writers that as high intellectual powers are advantageous to a nation, the old Greeks, who stood some grades higher in intellect than any race that has ever 25 Dr. Duncan remarks (' Fecund- '■'■ from the unmarried side to the ity, Fertility,' &c., 1871, p. 334) on " married, leaving the unmarried this subject; "At every age the "columns crowded with the sickly " healthy and beautiful go over " and unfortunate." Chap V. Civilised Nations. 1 41 existed,"^ ought, if the power of natural selection were real, to have risen still higher in the scale, increased in number, and stocked the whole of Europe. Here we have the tacit assump- tion, so often made with respect to corporeal structures, that there is some innate tendency towards continued development in mind and body. But development of all kinds depends on many concurrent favourable circumstances. Natural selection acts only tentatively. Individuals and races may have acquired cer- tain indisputable advantages, and yet have perished from failing in other characters. The Greeks may have retrograded from a want of coherence between the many small states, from the small size of their whole country, from the practice of slavery, or from extreme sensuality ; for they did not succumb until " they were " enervated and corrupt to the very core." '^ The western nations of Europe, who now so immeasurably surpass their former savage progenitors, and stand at the summit of civilisation, owe little or none of their superiority to direct inheritance from the old Greeks, though they owe much to the written works of that wonderful people. Who can positively say why the Spanish nation, so dominant at one time, has been distanced in the race. The awakening of the nations of Europe from the dark ages is a still more perplex- ing problem. At that early period, as Mr. Galton has remarked, almost all the men of a gentle nature, those given to meditation or culture of the mind, had no refuge except in the bosom of a Church which demanded celibacy ;^^ and this could hardly fail to have had a deteriorating influence on each successive generation. During this same period the Holy Inquisition selected with extreme care the freest and boldest men in order to burn or imprison them. In Spain alone some of the best men — those who doubted and questioned, and without doubting there can be no progress — were eliminated during three cen- turies at the rate of a thousand a year. The evil which the Catholic Church has thus effected is incalculable, though no doubt counterbalanced to a certain, perhaps to a large, extent in other ways; nevertheless, Europe has progressed at an un- paralleled rate. 2® See the ingenious and original 257) advances arguments on the argument on this subject by Mr. othi'r side. Sir C. Lyell had already Galton, 'Hereditary Genius,' i)p. ('Principles of Geology,' vol. .1. 340-342. 1868, p. 489) in a striking passage ^^ Mr. Greg, 'Eraser's Magazine,' called attention to the evil inHucnce Sept. 1868, p. 357. of the Holy Inquisition in having, ^® 'Hereditary Genius,' 1870, pp. through selection, lowered the gene- 357-359. The Rev. F. W. Farrar ral standard of intelligence in Eu- (' Fraser's Mag.,' Aug. 1870, p. rope. 142 The Descent of Alan. Pabt I. The remarkable success of the English as colonists, compared to other European nations, has been ascribed to their " daring " and persistent energy ; " a result which is xvell illustrated by comparing the progress of the Canadians of English and French extraction ; but who can say how the EngUsh gained their energy ? There is apparently much truth in the belief that the wonderful progress of the United States, as well as the character of the people, are the results of natural selection ; for the more ener- getic, restless, and courageous men from all parts of Europe have emigrated during the last ten or twelve generations to that great country, and have there succeeded best.-^ Looking to the distant future, I do not think that the Eev. Mr. Zincke takes an exaggerated view when he says :^ '' All other series of events — " as that which resulted in the cultui'e of mind in Greece, and "that which resulted in the emj^ire of Piome— only appear to " have purpose and value when viewed in connection with, or " rather as subsidiary to ... . the gi'eat stream of Anglo-Saxon " emigration to the west." Obscure as is the problem of the advance of civilisation, we can at least see that a nation which produced during a lengthened period the greatest number of highly intellectual, energetic, brave, patriotic, and benevolent men, would generally prevail over less favoured nations. Natural selection follows from the struggle for existence ; and this from a rajDid rate of increase. It is impossible not to regret bitterly, but whether wisely is another question, the rate at which man tends to increase ; for this leads in barbarous tribes to infanticide and many other evils, and in civilised nations to abject poverty, celibacy, and to the late marriages of the prudent. But as man suffei-e from the same physical evils as the lower animals, he has no right to expect an immunity from the evils consequent on the struggle for existence. Had he not been sub- jected during primeval times to natural selection, assuredly he would never have attained to his present rank. Since we see in many parts of the world enormous areas of the most fertile land capable of supporting numerous happy homes, but peopled only by a few wandering savages, it might be argued that the struggle for existence had not been sufficiently severe to force man up- wards to his highest standard. Judging from all that we know of man and the lower animals, there has always been sufficient variability in their intellectual and moral faculties, for a steady advance through natural selection. No doubt such advance 29 Mr. Gallon, ' Macmillau's and National Life,' Dec. 1869, p. 184. Magazine,' August, 1865, p. 32 o. ^o ^Last Winter in the United See also, 'Nature,' 'On Darwinism States,' 1868, p. 29. Chap. V. Civilised Nations. 143 demands many favourable concurrent circumstances ; but it may well be doubted whether the most favourable would have sufficed, had not the rate of increase been rapid, and the consequent struggle for existence extremely severe. It even appears from what we see, for instance, in parts of S. America, that a people which may be called civilised, such as the Spanish settlers, is liable to become indolent and to retrograde, when the con- ditions of life are very easy. With highly civilised nations con- tinued progress depends in a subordinate degree on natural selection-; for such nations do not supplant and exterminate one another as do savage tribes. Nevertheless the more intelligent members within the same community will succeed better in the long run than the inferior, and leave a more numerous progeny, and this is a form of natural selection. The more efficient causes of progress seem to consist of a good education during youth whilst the brain is impressible, and of a high standard of excellence, inculcated by the ablest and best men, embodied in the laws, customs and traditions of the nation, and enforced by public opinion. It should, however, be borne in mind, that the enforcement of public opinion depends on our appreciation of the approbation and disapprobation of others ; and this apprecia- tion is founded on our sympathy, which it can hardly be doubted was originally developed through natural selection as one of the most important elements of the social instincts.^^ On the evidence that all civUked nations ivere once harlarotis. — The present subject has been treated in so full and admirable a manner by Sir J. Lubbock,"^ Mr. Tylor, Mr. M'Lenuan, and others, that I need here give only the briefest summary of their results. The arguments recently advanced by the Duke of ArgylP^ and formerly by Archbishop Whately, in favour of the belief that man came into the world as a civilised being, and that all savages have since undergone degradation, seem to me weak in comparison with those advanced on the other side. Many nations, no doubt, have fallen away in civilisation, and some may have lapsed into utter barbarism, though on this latter head I have met with no evidence. The Fuegians were probably compelled by other conquering hordes to settle in their inhospitable country, and they may have become in consequence somewhat more degraded; but it would be difficult to prove " I am much iudebted to Mr. '^ 'On the Origin of Civilisation," John Morley for some good criti- * Proc. Ethnological Soc' Nov. 26 cisms on this subject: see, also, 1867. Broca, 'Les Selections,' 'Kevue d'Au- ^■^ ' Primeval Man,' 18G9. thropologie,' 1872. 144 ^^^^ Descent of Man. Part I. that they have fallen much below the Botocudos, who inhabit the finest parts of Brazil. The evidence that all civilised nations are the descendants of barbarians, consists, on the one side, of clear traces of their former low condition in still-existing customs, beliefs, language, &c.; and on the other side, of proofs that savages are inde- pendently able to raise themselves a few steps in the scale of civilisation, and have actually thus risen. The evidence on the first head is extremely curious, but cannot be here given : I refer to such cases as that of the art of enumeration, which, as Mr. Tylor clearly shews by reference to the words still used in some places, originated in counting the fingers, first of one hand and then of the other, and lastly of the toes. We have traces of this in our own decimal system, and in the Eoman numerals, where, after the V., which is supposed to be an abbreviated picture of a human hand, we pass on to VI., &c., when the other hand no doubt was used. So again, " when we speak of three-score and " ten, we are counting by the vigesimal system, each score thus " ideally made, standing for 20— for ' one man ' as a Mexican or " Carib would put it."^^ According to a large and increasing school of philologists, every language bears the marks of its slow and gradual evolution. So it is with the art of writing, for letters are rudiments of pictorial representations. It is hardly possible to read Mr. M'Lennan's work^^ and not admit that almost all civilised nations still retain traces of such rude habits as the forcible capture of wives. What ancient nation, as the same author asks, can be named that was originally mono- gamous ? The primitive idea of justice, as shewn by the law of battle and other customs of which vestiges still remain, was likewise most rude. Many existing superstitions are the remnants of former false religious beliefs. The highest form of religion — the gi-and idea of God hating sin and loving right- eousness— was unknown during primeval times. • . Turning to the other kind of evidence : Sir J. Lubbock has shewn that some savages have recently improved a little in some of their simpler arts. From the extremely curious account which he gives of the weapons, tools, and arts, in use 3* ' Royal Institution of Great ' A Conjectural Solution of the Britain,' March 15, 1867. Also, Origin of the Class, System of ' Researches into the Early History Relationship,' in ' Proc. American of Mankind,' 1865. Acad, of Sciences,' vol. vii. Feb. 35 'Primitive Marriage,' 1865. 1868. Prof. Schaaffhausen ('An- See, likewise, an excellent article, thropolog. Review,' Oct. 1869, p. evidently by the same author, in 373) remarks on " the vestiges of the 'North British Review,' July, "human sacrifices found both in 1869. Also, Mr, L. H. Morgjin, " Homer and the Old Testament." CiiAr. V. Nations. 1 45 amongst savages in yarious parts of the world, it cannot be doubted that these have nearly all been independent discoveries, excepting perhaps the art of making fire.^'^ The Australian boomerang is a good instance of one such independent discovery. The Tahitians when first visited had advanced in many respects beyond the inhabitants of most of the other Polynesian islands. There are no just grounds for the belief that the high culture of the native Peruvians and Mexicans was derived from abroad ; ^^ many native plants were there cultivated, and a few native animals domesticated. We should bear in mind that, judging from the small influence of most missionaries, a wandering crew from some semi-civilised land, if washed to the shores of America, would not have produced any marked eifect on the natives, unless they had already become somewhat advanced. Looking to a very remote period in the history of the world, we find, to use Sir J. Lubbock's well-known terms, a paleolithic and neolithic period; and no one will pretend that the art of grinding rough flint tools was a borrowed one. In all parts of EurojDe, as far east as Greece, in Palestine, India, Japan, New Zealand, and Africa, including Egypt, flint tools have been discovered in abundance; and of their use the existing in- habitants retain no tradition. There is also indirect evidence of their former use by the Chinese and ancient Jews. Hence there can hardly be a doubt that the inhabitants of these countries, which include nearly the whole civilised world, were once in a barbarous condition. To believe that man was abori- ginally civilised and then suffered utter degradation in so many regions, is to take a pitiably low view of human nature. It is apparently a truer and more cheerful view that progress has been much more general than retrogression ; that man has risen, though by slow and interrupted steps, from a lowly condition to the highest standard as yet attained by him in knowledge, morals and reUgion. 3« Sir J. Lubbock, 'Prehistoric edit., 1870. Times,' 2ad edit. 1869, chap. xv. ^r j^j.. F. Miiller has made some and xvi. et passim. See also the good remarks to this effect in the excellent 9th chapter in Trior's ' Reise der Novara : Anthropolog. Early History of Mankind,'' 2nd Theil,' Abtheil. iii. 18G8, s. 127. 146 The Descent of Maiu Pakt I. CHAPTER YI. On the Affinities and Genealogy cf Man. Position of man in the animal series — The natui'al system genealogical — ■ Adaptive characters of slight value — Various small points of resem- blance between man and the Quadrumana — Rank of man in the natural system — Birthplace and antiquity of man — Absence of fossil connecting- links — Lower stages in the genealogy of man, as inferred, firstly from his affinities and secondly from his structure — Early androgynous con- dition of the Vertebrata — Conclusion. Even if it be granted that the diflference between man and his nearest allies is as great in cori)oreal structure as some natu- ralists maintain, and although we must grant that the differ- ence between them is immense in mental power, yet the facts given in the earlier chapters appear to declare, in the plainest manner, that man is descended from some lower form, notwith- standing that connecting-links have not hitherto been dis- covered. Man is liable to numerous, slight, and diversified variations, which are induced by the same general causes, are governed and transmitted in accordance with the same general laws, as in the lower animals. Man has multiplied so rapidly, that ho has necessarily been exposed to struggle for. existence, and con- sequently to natural selection. He has given rise to many races^ some of which differ so much from each other, that they have often been ranked by naturalists as distinct species. His body is constructed on the same homological jDlan as that of other mammals. He passes thi'ough the same phases of embryo- logical development. He retains many rudimentary and useless structures, which no doubt were once serviceable. Characters occasionally make their re-appearance in him, which we have reason to believe were possessed by his early progenitors. If the origin of man had been wholly different from that of all other animals, these various appearances would be mere empty deceptions ; but such an admission is incredible. These appear- ances, on the other hand, are intelligible, at least to a large extent, if man is the co-descendant with other mammals of some unkno\\Ti and lower form. Some natm-alists, from being deeply impressed with the mental and spiritual powers of man, have divided the whole organic world into three kingdoms, the Human, the Animal, CiiAi'. VI. Affinities and Genealogy. 147 and the Vegetable, thus giving to man a separate kingdom.' Spiritual powers cannot be compared or classed by the natu- ralist: but he may endeavour to shew, as I have done, that the mental faculties of man and the lower animals do not differ in kind, although immensely in degree. A difference in degree, however great, does not justify us in placing man in a distinct kingdom, as will perhaps be best illustrated by comparing the mental j^owers of two insects, namely, a coccus or scale-insect and an ant, which undoubtedly belong to the same class. The difference is here greater than, though of a somewhat different kind from, that between man and the highest mammal. The female coccus, whilst young, attaches itself by its proboscis to a plant ; sucks the sap, but never moves again ; is fertilised and lays eggs ; and this is its whole history. On the other hand, to describe the habits and mental powers of worker-ants, would require, as Pierre Huber has shewn, a large volume ; I may, however, briefly specify a few points. Ants certainly communicate information to each other, and several unite for the same work, or for games of play. They recognise their fellow-ants after months of absence, and feel sympathy for each other. They build gi'eat edifices, keep them clean, close the doors in the evening, and post sentries. They make roads as well as tunnels under rivers, and temporary bridges over them, by clinging together. They collect food for the community, and when an object, too large for entrance, is brought to the nest, they enlarge the door, and afterwards build it up again. They store up seeds, of which they prevent the germination, and which, if damp, are brought up to the surface to dry. They keep aphides and other insects as milch-cows. They go out to battle in regular bands, and freely sacrifice their lives for the common weal. They emigrate ac- cording to a preconcerted plan. They capture slaves. They move the eggs of their aphides, as well as their own eggs and cocoons, into warm parts of the nest, in order that they may be quickly hatched ; and endless similar facts could be given.^ On the whole, the difference in mental power between an ant and a coccus is immense ; yet no one has ever dreamed of placing these insects in distinct classes, much less in distinct kingdoms. IS'o * Isidore GeofFroy St.-Hilaire gives of auts are given by Mr. Belt, in a detailed account of the position in his 'Naturalist in Kicaragua,' assigned to man by various natural- 1874. See also Mr. Sloggridge's ists in their classifications: 'Hist, admirable work, ' Harvesting Ants,' Nat. Gen,' torn. ii. 1859, pp. 170- &e., 1873, also ' L'Instinct chez les 189. Insectes,' by M. George Pouchet, - Some of the most interesting 'Revue des Deux Moudes,' Feb. facts ever published on the habits 1870 p. 682. 148 The Descent of Man. Part T. doubt the difference is bridged over by other insects ; and this is not the case with man and the higher apes. But we have every reason to believe that the breaks in the series are simply the results of many foi-ms having become extinct. Professor Owen, relying chiefly on the structure of the brain, has divided the mammalian series into four sub-classes. One of these he devotes to man; in another he places both the Marsupials and the Monotremata; so that he makes man as distinct from all other mammals as are these two latter groups conjoined. This view has not been accepted, as far as I am aware, by any naturalist capable of forming an independent judgment; and therefore need not here be further considered. We can understand why a classification founded on any single character or organ— even an organ so wonderfully complex and important as the brain — or on the high development of the mental faculties, is almost sure to prove unsatisfactory. This principle has indeed been tried with hymenopterous insects; but when thus classed by their habits or instincts, the arrange- ment proved thoroughly artificial.^ Classifications may, of course, be based on any character whatever, as on size, colour, or the element inhabited; but naturalists have long felt a profound conviction that there is a natural system. This system, it is now generally admitted, must be, as far as possible, genealogical in arrangement, — that is the co-descendants of the same form must be kept together in one group, apart from the co-descendants of any other form ; but if the parent-forms are related, so will be their descendants, and the two groups to- gether will form a larger group. The amount of difference between the several groups — that is the amount of modification which each has undergone— is expressed by such terms as genera, families, orders, and classes. As we have no record of the lines of descent, the pedigree can be discovered only by observing the degrees of resemblance between the beings which are to be classed. For this object numerous points of resem- blance are of much more importance than the amount of similarity or dissimilarity in a few points. If two languages were found to resemble each other in a multitude of words and points of construction, they would be universally recognised as having sprung from a common source, notwithstanding that they differed greatly in some few words or points of construction. But with organic beings the points of resemblance must not consist of adaptations to similar habits of fife : two animals may, for instance, have had their whole frames modified for living in ' Westwood, ' Modern Class of Insects/ vol. ii. 1840, p. 87. Chap. XL Affinities and Genealogy. 149 the ■water, and yet they will not be bronglit any nearer to each other in the natural system. Hence "sve can see how it is that resemblances in several unimportant structures, in useless and rudimentary organs, or not now functionally active, or in an embryological condition, are by far the most serviceable for clas- sification ; for they can hardly be due to adaptations within a late period ; and thus they reveal the old lines of descent or of true affinity. We can further see why a gi-eat amount of modification in some one character ought not to lead us to separate widely any two organisms. A part which already differs much from the same part in other allied forms has already, according to the theory of evolution, varied much ; consequently it would (as long as the organism remained exposed to the same exciting con- ditions) be liable to further variations of the same kind ; and these, if beneficial, would be preserved, and thus be continually augmented. In many cases the continued development of a part, for instance, of the beak of a bird, or of the teetli of a mammal, would not aid the species in gaining its food, or for any other object ; but with man we can see no definite limit to the con- tinued development of the brain and mental faculties, as far as advantage is concerned. Therefore in determining the position of man in the natural or genealogical system, the extreme de- velopment of his brain ought not to outweigh a multitude of resemblances in other less important or quite unimportant points. The greater number of naturalists who have taken into con- sideration the whole structure of man, including his mental faculties, have followed Blumenbach and Cuvier, and have placed man in a separate Order, under the title of the Bimana, and therefore on an equality with the orders of the Quadrumana, Carnivora, &c. Recently many of our best naturalists have recurred to the view first propounded by Linnscus, so remarkable for his sagacity, and have placed man in the same Order with the Quadrumana, under the title of the Primates. The justice of this conclusion will be admitted : for in the first place, we must bear in mind the comparative insignificance for classification of the great development of the brain in man, and that the strongly-marked differences between the skulls of man and tlK^ Quadrumana (lately insisted upon by Bischoff, Aeby, and others) apparently follow from their differently developed brains. In the second place, we must remember that nearly all the other and more important difi'crences Ixitween man and the Quadrumana are manifestly adaptive in their nature, and relate cliiefly to tljo erect position of man ; such as the structure of his hand, /oot, 1 50 The Descent of Man. Part I. and pelvis, the curvature of his spine, and the position of his head. The family of Seals offers a -good illustration of the small importance of adaptive characters for classification. These animals differ from all other Carnivora in the form of their bodies and in the structure of their limbs, far more ihan does man from the higher apes ; yet in most systems, from ihat of Cuvier to the most recent one by Mr. Flower/ seals are ranked as a mere family in the Order of the Carnivora. If man had not been his own classifier, he would never have thought of founding a separate order for his own reception. < It would be beyond my limits, and quite beyond my knowledge, even to name the innumerable points of structure in which man agrees with the other Primates. Our great anatomist and l^hilosopher. Prof. Huxley, has fully discussed this subject,^ and concludes that man in all parts of his organisation differs less from the higher apes, than these do from the lower members of the same group. Consequently there "is no justification for " placing man in a distinct order." In an early part of this work I brought forward various facts, shewing how closely man agrees in constitution with the higher mammals ; and this agreement must depend on our close similarity in minute structure and chemical composition. I gave, as instances, our liability to the same diseases, and to the attacks of allied parasites ; our tastes in common for the same stimulants, and the similar effects produced by them, as well as by various drugs, and other such facts. As small unimportant points of resemblance between man and the Quadrumana are not commonly noticed in systematic works, and as, when numerous, they clearly reveal our relationship, I will specify a few such points. The relative position of our features is manifestly the same ; and the various emotions are displayed by nearly similar movements of the muscles and skin, chiefly above the eyebrows and round the mouth. Some few expressions are, indeed, almost the same, as in the weeping of certain kinds of monkeys and in the laughing noise made by others, during which the corners of the mouth are drawn back- wards, and the lower eyelids wrinkled. The external ears are curiously alike. In man the nose is much more prominent than in most monkeys ; but we may trace the commencement of an aquiline curvature in the nose of the Hoolock Gibbon ; and this in the Semnopitliecus nasica is carried to a ridiculous extreme. The faces of many monkeys are ornamented with beards, whiskers, or moustaches. The hair on the head grows to a great "» 'Pvoc. Zoolog. Soc' 1863, p. 4. . * ' Evidence as to Man's Piace in Nature,' 1863, p. 70, et passim. CH4P. vr. Affinities and Genealogy. 151 length in some species of Scmnopithccus ;'' and in the Bonnet monkey (Macacus radiatus) it radiates from a point on the crown, with a parting down the middle. It is commonly said that the forehead gives to man his noble and intellectual appearance ; but the thick hair on the head of the Bonnet monkey terminates downwards abruptly, and is succeeded by hair so short and fine that at a little distance the forehead, with the exception of the eyebrows, appears quite naked. It has been erroneously asserted that eyebrows are not present in any monkey. In the species just named the degree of nakedness of the forehead differs in different individuals ; and Eschricht states ^ that in our children the limit between the hairy scalp and the naked forehead is sometimes not well defined; so that here we seem to have a trifling case of reversion to a yjrogenitor, in whom the forehead had not as yet become quite naked. It is well known that the hair on our arms tends to converge from above and below to a point at the elbow. Tliis curious arrangement, so unlike that in most of the lower mammals, is common to the gorilla, chimpanzee, orang, some species of Hylobates, and even to some few American monkeys. But in IJylohates agilis the hair on the fore-arm is directed downwards or towards the wrist in the ordinary manner ; and in //. lar it is nearly erect, with only a very slight forward inclination ; so that in this latter species it is in a transitional state. It can hardly be doubted that with most mammals the thickness of the hair on the back and its direction, is adapted to throw off the rain ; even the transverse hairs on the fore- legs of a dog may serve for this end when he is coiled up asleep. Mr. Wallace, who has carefully studied the habits of the orang, remarks that the convergence of the hair towards the elbow on the arms of the orang may be explained as serving to throw off the rain, for this animal during rainy weather sits with its arms bent, and with the hands clasped round a branch or over its head. According to Livingstone, the gorilla also " sits in pelting rain with his hands over his head."" If the above explanation is correct, as seems probable, the direc- tion of the hair on our own arms offers a curious record of our former state ; for no one supposes that it is now of any use in throwing off the rain ; nor, in our jDresent erect condition, is it properly directed for this purpose. It would, however, be rash to trust too much to the principle of adaptation in regard to the direction of the hair in man or his « Isid. GeoflFroy, ' Hist. Xiit. Gen.' Anat. und Phys.' 1837, s. 51. torn. ii. 1859, p. 217. " Quoted by Reade, 'The African ^ ' Ueber die ILichtung der Sketch Book, ''vol. i., 1873, p. 152. Haare,' kc, Muller's 'Archiv I'iir 152 The Descent of Man. ' Paut I. early iDrogenitors ; for it is impossible to study the figures given by Escbricht of the arrangement of the hair on the human foetus (this being the same as in the adult) and not agree with this excellent observer that other and more complex causes have intervened. The points of convergence seem to stand in some relation to those points in the embryo which are last closed in duiing development. There appears, also, to exist some relation between the arrangement of the hair on the limbs, and the course of the medullary arteries.^ It must not be supposed that the resemblances between man and certain apes in the above and many other points — such as in having a naked forehead, long tresses on the head, &c. — are all necessarily the result of unbroken inheritance from a common progenitor, or of subsequent reversion. Many of these resem- blances are more probably due to analogous variation, which follows, as I have elsewhere attempted to shew,^" from co-descended organisms having a similar constitution, and having been acted on by like causes inducing similar modifications. "With respect to the similar direction of the hair on the fore-arms of man and certain monkeys, as this character is common to almost all the anthropomorphous apes, it may probably be attributed to in- heritance; but this is not certain, as some very distinct American monkeys are thus characterised. Although, as we have now seen, man has no just right to form a separate Order for his own reception, he may perhaps claim a distinct Sub-order or Family. Prof. Huxley, in his last work," divides the Primates into three Sub-orders; namely, the An- thropidse with man alone, the Simiadae including monkeys of all kinds, and the Lemuridse with the diversified genera of lemurs. As far as differences in certain important points of structure are concerned, man may no doubt rightly claim the rank of a Sub- order ; and this rank is too low, if we look chiefly to his mental faculties. Nevertheless, from a genealogical point of view it appears that this rank is too high, and that man ought to form merely a Family, or possibly even only a Sub-family. If we imagine three lines of descent proceeding from a common stock, it is quite conceivable that two of them might after the lapse of ^ On the hair iu Hylobates, see the Theory of Natural Selection,' 'Nat. Hist, of Mammals,' by C. L. 1870, p. 344. JMartin, 1841, p. 415. Also, l^iJ. ^^ 'Origin of Species,' 5th edit. Geoffroy on the American monkeys 1869, p. 194. 'The Variation of and other kinds, ' Hist. Xat. Gen.' Animals and Plants under Domesti- vol. ii. 1859, p. 216, 243. Esch- cation,' vol. ii. 1868, p. 348. richt, ibiil. s. 46, 55, 61. Owen, ^^ ' An Introduction to the Classi- ' Aunt, of Vertebrates,' vol. iii. p. fication of Animals,' 1869, p. 99. 619. Wallace, 'Contributions to Chap. Y I. Affinities and Genealogy. 153 ages be so slightly changed as still to remain as species of the same genus, whilst the third line might become so greatly modified as to deserve to rank as a distinct Sub- family, Family, or even Order. But in this case it is almost certain that the third line would still retain through inheritance numerous small points of resemblance with the other two. Here, then, would occur the difficulty, at present insoluble, how much weight we ought to assign in our classifications to strongly-marked dif- ferences in some few points, — that is, to the amount of modifi- cation undergone ; and how much to close resemblance in numerous unimportant points, as indicating the lines of descent or genealogy. To attach much weight to the few but strong differences is the most obvious and perhaps the safest course, though it appears more correct to pay great attention to the many small resemblances, as giving a truly natural classification. In forming a judgment on this head with reference to man, we must glance at the classification of the Simiadae. This family is divided by almost all naturalists into the Catarhine group, or Old World monkeys, all of which are characterised (as their name exjDresses) by the peculiar structure of their nostrils, and by having four premolars in each jaw; and into the Platyrhine group or New World monkeys (including two very distinct sub-groups), all of which are characterised by differently constructed nostrils, and by having six j^remolars in each jaw. Some other small differences might be mentioned. Now man unquestionably belongs in his dentition, in the structure of his nostrils, and some other respects, to the Catarhine or Old World division ; nor does he resemble the Platyrhines more closely than the Catarhines in any characters, excepting in a few of not much importance and apparently of an adaptive nature. It is therefore against all probability that some New World species should have formerly varied and produced a man-like creature, with all the distinctive characters proper to the Old World division ; losing at the same time all its own distinctive characters. There can, consequently, hardly be a doubt that man is an off-shoot from the Old World Simian stem ; and that under a genealogical point of view, he must be classed with the Catarhine division.^^ The anthropomorphous apes, namely the gorilla, chimpanzee, ^2 This is nearly the same classifi- adse which answer to the Catarhines, cation as that provisionally adopted the Cebidae, and the Ilapalida?, — by ]Mr. St. George Mivart (' Tran- these two latter groups answering sact. Philosoph. Soc' 1867, p. 300), to the Platyrhines. Mr. Mivart who, after separating the Lemuridffi, still abides by the same view; see divides the remainder of the Pri- ' Nature,' 1871, p. 481. mates into the Hominidac, the Simi- 8 154 The Descent of Man. Part I. orang, and hylobates, are by most naturalists separated from the other Old ^Yorld monkeys, as a distinct sub-group. I am aware that Gratiolet, relying on the structure of the brain, does not admit the existence of this sub-group, and no doubt it is a broken one. Thus the orang, as l\Ir. St. G. Mivart remarks,^^ '' is one of the " most peculiar and aberrant forms to be found in the Order." The remaining non-anthropomorphous Old World monkeys, are again divided by some naturalists into two or three smaller sub- groups ; the genus Semnopithecus, with its pecuhar sacculated stomach, being the type of one such sub-group. But it appears from M. Gaudry's wonderful discoYeries in Attica, that during the Miocene period a form existed there, which connected Semnopithecus and Macacus ; and this probably illustrates the manner in which the other and higher grouj^s were once blended together. If the anthropomorphous apes be admitted to form a natural sul>group, then as man agrees with them, not only in all those characters which he possesses in common with the whole Catarhine groui^, but in other peculiar characters, such as the absence of a tail and of callosities, and in general appearance, we may infer that some ancient member of the anthropomorphous sub-group gave birth to man. It is not probable that, through the law of analogous yariation, a member of one of the other lower sub-groups should have given rise to a man-like creature, resembling the higher anthropomorphous apes in so many respects. No doubt man, in comparison with most of his allies, has undergone an extraordinary amount of modification, chiefly in consequence of the great development of his brain and his erect position ; nevertheless, we should bear in mind that he " is " but one of several exceptional forms of Primates." ^^ - Every naturalist, who believes in the principle of evolution, will grant that the two main divisions of the Simiadte, namely the Catarhine and Platyrhine monkeys, with their sub-groups, have all proceeded from some one extremely ancient progenitor. The early descendants of this progenitor, before they had diverged to any considerable extent from each other, would still have formed a single natural group ; but some of the species or inci]oient genera would have already begun to indicate by their diverging characters the future distinctive marks of the Catarhine and Platyrhine divisions. Hence the members of this supposed ancient group would not have been so uniform in their den- tition, or in the structure of their nostrils, as are the existing 13 ' Transact, Zoolog. Soc' vol. vi. ^^ Mr. St. G. Mivart, ' Transact. IS67, p. 2U. Phil. Soc' 1867, p. 410. Chap. VI. Affinities and Genealogy. 155 Catarhine monkeys in one way and the Platyrhinos in another way, but would have resembled in this respect the allied Lemu- ridx, which differ greatly from each other in the form of their muzzles/^ and to an extraordinary degree in their dentition. The Catarhine and Platyrhine monkeys agree in a multitude of characters, as is shewn by their unquestionably belonging to one and the same Order. The many characters which they possess in common can hardly have been independently acquired by so many distinct species ; so that these characters must have been inherited. But a naturalist would undoubtedly have ranked, as an ape or a monkey, an ancient form which possessed many characters common to the Catarhine and Platyrhine monkeys, other characters in an intermediate con- dition, and some few, perhaps, distinct from those now found in either group. And as man from a genealogical point of view belongs to the Catarhine or Old World stock, we must conclude, however much the conclusion may revolt our pride, that our early progenitors would have been properly thus designated.'" But we must not fall into the error of supposing that the early progenitor of the whole Simian stock, including man, was iden- tical with, or even closely resembled, any existing ape or monkey. 0)1 the Dirthi.lace and Antiquify of Man. — We are naturally led to enquire, where was the birthplace of man at that stage of descent when our progenitors diverged from the Catarhine stock ? The fact that they belonged to this stock clearly shews that they inhabited the Old World ; but not Australia nor any oceanic island, as we may infer from the laws of geographical distribution. In each great region of the world the living mammals are closely related to the extinct sjDecies of the same region. It is therefore probable that Africa was formerly in- habited by extinct apes closely allied to the gorilla and chim- panzee ; and as these two species are now man's nearest allies, it is somewhat more probable that our early progenitors lived on the African continent than elsewhere. But it is useless to speculate on this subject; for two or three anthropomorphous apes, one the Dryopithccus ^^ of Lartet, nearly as large as a man, •^ Messrs. ]\Iurie and Mivart on his ' Natiirliche S-hopfungsge- the Lemuroidea, 'Transact. Zoolui;. schichte,' 18G8, iu which he gives Sue' vol. vii. 18G9, p. 5. iu detail his views on the genealogy '^ Hilckel has come to this same of man. conclusion. See ' Ueber die Ent- " Dr. C. Forsyth Major, ' Sur les stehung des Menschengeschlechts,' Singes Fossiles trouves en Italie :* in Virchow's ' Sammlung. gemein. ' Soc.Ital. des Sc. Nat.' torn. xv. 1872. wissen. Vortriige,' 18G8, s. Gl. Also 156 The Descent of Man. Part 1. and closely allied to Hylobates, existed in Europe during the Miocene age ; and since so remote a period the earth has certainly undergone many great revolutions, and there has been ample time for migration on the largest scale. At the period and place, wheneyer and whereTer it was, when man first lost his hairy coYering, he probably inhabited a hot country ; a circumstance favourable for the frugiferous diet on wliich, judging from analogy, he subsisted. We are far from knowing how long ago it was when man first diverged from the Catarhine stock; but it may have occurred at an epoch as remote as the Eocene period; for that the higher apes had diverged from the lower apes as early as the Upper Miocene period is shewn by the existence of the Dryopithecus. We are also quite ignorant at how rajDid a rate organisms, whether high or low in the scale, may be modified under favourable circumstances ; we know, however, that some have retained the same form during an enormous lapse of time. From what we see going on under domestication, we learn that some of the co-descendants of the same species may be not at all, some a little, and some greatly changed, all within the same period. Thus it may have been with man, who has undergone a great amount of modification in certain characters in comparison with the higher apes. The great break in the organic chain between man and his nearest allies, which cannot be bridged over by any extinct or living species, has often been advanced as a grave objection to the belief that man is descended from some lower form ; but this objection will not appear of much weight to those who, from general reasons, believe in the general princij)le of evolution. Breaks often occur in all parts of the series, some being wide, sharp and defined, others less so in various degrees ; as between the orang and its nearest allies — betw^een the Tarsius and the other Lemuridse — between the elephant, and in a more striking manner between the Ornithorhynchus or Echidna, and a.l other mammals. But these breaks depend merely on the number of related forms which have become extinct. At some future period, not very distant as measured by centuries, the civilised races of man will almost certainly exterminate, and replace, the savage races throughout the world. ^ At the same time the anthro- pomorphous apes, as Professor Schaafifliausen has remarked,^^ will no doubt be exterminated. The break between man and his nearest allies will then be wider, for it will intervene between man in a more civilised state, as we may hope, even than the Caucasian, and some ai)e as low as a baboon, instead of as no «v between the negro or Australian and the gorilla. " ' Anthropological Review/ April, 1867, p. 236. Chap. YI. Affinities and Genealogy. 1 57 "With respect to the absence of fossil remains, serving to connect man with his ape-like progenitors, no one will lay much stress on this fact who reads Sir C. Ly ell's discussion,'^ where he shews that in all the vertebrate classes the discovery of fossil remains has been a very slow and fortuitous process. Nor should it be forgotten that those regions which are the most hkely to afford remains connecting man with some extinct ape- like creature, have not as yet been searched by geologists. Lower Stages in the Genealogy of Man. — We have seen that man appears to have diverged from the Catarhine or Old World division of the Simiadae, after these had diverged from the New World division. We will now endeavour to follow the remote traces of his genealogy, trusting principally to the mutual affinities between the various classes and orders, with some slight reference to the periods, as far as ascertained, of their successive appearance on the earth. The Lemuridae stand below and near to the Simiadse, and constitute a very distinct family of the Primates, or, according to Hackel and others, a distinct Order. This group is diversified and broken to an extraordinary degree, and includes many aberrant forms. It has, therefore, i:)robably suffered much extinction. Most of the remnants survive on islands, such as Madagascar and the Malayan archipelago, where they have not been exposed to so severe a competition as they would have been on well-stocked continents. This group likewise presents many gradations, leading, as Huxley remarks,-*' '' insensibly from the crown and " summit of the animal creation down to creatures from which " there is but a step, as it seems, to the lowest, smallest, and " least intelligent of the placental mammalia." From these various considerations it is probable that the Simiadai were originally developed from the progenitors of the existing Lemnridaj ; and these in their turn from forms standing very low in the mammalian series. The Marsupials stand in many important characters below the placental mammals. They appeared at an earlier geological period, and their range was formerly much more extensive than at present. Hence the Placentata are generally supposed to have been derived from the Implacentata or Marsui)ials; not, however, from forms closely resembling the existing Mar- supials, l)ut from their early progenitors. The Monotremata are plainly allied to the Marsupials, forming a third and still lower '» 'Elements of Geology,' 1865, 20 < Man's Place in Nature,' p. pp. 583-585. ' Antiquity of Man,' 105. 1863, p. 145. 158 The Descent of Man, Paut I division in tlie great mammalian series. They are represented at the present day solely by the Ornithorhynchus and Echidna ; and these two fonns may be safely considered as relics of a much larger group, representatives of which have been preserved in Australia through ^ome favourable concurrence of circum- stances. The Monotremata are eminently interesting, as leading in several important points of structure towards the class of reptiles. In attempting to trace the genealogy of the Mammalia, and therefore of man, lower down in the series, we become involved in greater and greater obscurity ; but as a most capable judge, Mr. Parker, has remarked, we have good reason to believe, that no true bird or reptile intervenes in the direct line of descent. He who wishes to see what ingenuity and knowledge can effect, may consult Prof. Hackel's works.^^ I will content myself with a few general remarks. Every evolutionist will admit that the five great vertebrate classes, namely, mammals, birds, reptiles, amphibians, and fishes, are descended from some one prototype ; for they have much in common, especially during their embryonic state. As the class of fishes is the most lowly organised, and appeared before the others, we may conclude that all the members of the vertebrate kingdom are derived from some fish- like animal. The belief that animals so distinct as a monkey, an elephant, a humming-bird, a snake, a frog, and a fish, &c., could all have sprung from the same parents, will appear monstrous to those who have not attended to the recent progress of natural history. For this belief implies the former existence of links binding closely together all these forms, now so utterly unlike. Nevertheless, it is certain that groups of animals have existed, or do now exist, which serve to connect several of the great vertebrate classes more or less closely. We have seen that the Ornithorhynchus graduates towards reptiles ; and Prof. Huxley has discovered, and is confirmed by Mr. Cope and others, that the Dinosaurians are in many important characters intermediate between certain reptiles and certain birds— the birds referred to being the ostrich- tribe (itself evidently a widely-diffused remnant of a larger group) and the Archeopteryx, that strange Secondary bird, with a long lizard-like tail. Again, according to 21 Elaborate tables are given in the phylum or lines of descent of his * Generelle Morphologie ' (B. ii. the Vertebrata to be admirabl}' dis- s. cliii. and s. 425) ; and with more cussed by Hackel, although he differs especial reference to man in his on some points. He expresses, 'Natiirliche Schopfuugsgeschichte,' also, his high estimate of the 1868. Prof. Huxley, in reviewing general tenor and spirit of the this latter work ('The Academj-/ whole work. 18(39, p. 42) says, that he" considers 22 Palaeontology,' 1860, p. 199. Chap. VI. Affinities and Genealogy. 159 Prof. Owen,-2 the Tchthyosanrians— great sea-lizards furnished with paddles— present many affinities with fishes, or rather, according to Huxley, with amphibians ; a class which, including in its highest division frogs and toads, is plainly allied to the Ganoid fishes. These latter fishes swarmed during the earlier geological periods, and were constructed on what is called a generalised type, that is, they presented diversified affinities with other groups of organisms. The Lepidosiren is also so closely allied to amphibians and fishes, that naturalists long disputed in which of these two classes to rank it ; it, and also some few Ganoid fishes, have been preserved from ntter extinction by inhabiting rivers, which are harbours of refuge, and are related to the great waters of the ocean in the same way that islands are to continents. Lastly, one single member of the immense and diversified class of fishes, namely, the lancelet or amphioxus, is so different from all other fishes, that Hackel maintains that it ought to form a distinct class in the vertebrate kingdom. This fish is remarkable for its negative characters ; it can hardly be said to possess a brain, vertebral column, or heart, &c. ; so that it was classed by the older naturalists amongst the worms. Many years ago Prof. Goodsir perceived that the lancelet presented some affinities with the Ascidians, which are invertebrate, hermaphrodite, marine creatures permanently attached to a support. They hardly appear like animals, and consist of a simple, tough, leathery sack, with two small projecting orifices. They belong to the Molluscoida of Huxley— a lower division of the great kingdom of the Mollusca ; but they have recently been placed by some naturahsts amongst the Vermes or worms. Their larvae some- what resemble tadpoles in shape,-^ and have the power of swimming freely about. M. Kovalevsky -■* has lately observed that the larvae of Ascidians are related to the Vertebrata, in their manner of development, in the relative position of the nervous system, and in possessing a structure closely like the chorda dorsalis of vertebrate animals; and in this he has been since -^ At the Falkland Islands I had under a simple microscope, plainly tlie satisfaction of seeing, in April divided by transverse opaque parti- 1833, and therefore some years be- tions, which I presume represent tore any other naturalist, the loco- the great cells figured by Kovalev- motive larvae of a compound Asci- sky. At an early stage of develop- dian, closely allied to Synoicum, raent the tail was closely coiled but apparently renerically distinct round the head of the larva, from it. The tail was about five ^^ ' Memoiros de I'Acad. des times as long as the oblong head, Sciences de St. Pe'tersliourg,' torn. x. and terminated in a very fine fila- No. 15, 186G. ment. It was, as bketclied by me i6o The Descent of Man. Pakt I. confirmed by Prof. Kupffer. M. Kovalevsky writes to me from Naples, that he has now carried these observations yet further ; and should his results be well established, the whole will form a discovery of the very greatest value. Thus, if we may rely on embryology, ever the safest guide in classification, it seems that we have at last gained a clue to the source whence the Yertebrata were derived.^^ We should then be justified in believing that at an extremely remote period a group of animals existed, resembling in many respects the larvae of our present Ascidians, which diverged into two great branches— the one retrograding in development and producing the present class of Ascidians, the other rising to the crown and summit of the animal kingdom by giving birth to the Yertebrata. We have thus far endeavoured rudely to trace the genealogy of the Yertebrata by the aid of their mutual aflBnities. We will now look to man as he exists ; and we shall, I think, be able partially to restore the structure of our early progenitors, during successive iDeriods, but not in due order of time. This can be eff'ected by means of the rudiments which man still retains, by the characters which occasionally make their appearance in him through reversion, and by the aid of tlie principles of morphology and embryology. The various facts, to which I shall here allude, have been given in the previous chapters. The early progenitors of man must have been once covered with hair, both sexes having beards ; their ears were probably pointed, and capable of movement ; and their bodies were pro- vided with a tail, having the proper muscles. Their limbs and bodies were also acted on by many muscles which now only occasionally reappear, but are normally present in the Quadru- mana. At this or some earlier period, the great artery and nerve of the humerus ran thi'ough a supra-condyloid foramen. The intestine gave forth a much larger diverticulum or caecum than that now existing. The foot was then prehensile, judging from the condition of the great toe in the foetus ; and our progenitors, no doubt, were arboreal in their habits, and frequented some warm, forest-clad land. The males had great canine teeth, which 25 But I am bound to add that " peut produire la disposition fonda- some competent judges dispute this " mentale du type A-ertebre (I'ex- couclusion ; for instance, M. Giard, " istence d'une corde dorsale) chez in a series of papers in the 'Archives " un iuvertebre par la seule con- dc Zoologie Experimentale,' for 1872. " dition vitale de I'adaptation, Nevertheless, this naturalist re- " et cette simple possibilite du marks, p. 28i, " L'organisaiion de la "passage supprirae I'abime entre " larve ascidienne en dehors de " les deux sous-regnes, encore bien " toute hypothfese etde toutethebrie, *' qu'en ignore par oil le passage " nous montre comment la nature '• s'est fait en reality." Chap. VI. Affinities and Ge7iealogy. i6i served them as formidable weapons. At a miicli earlier period the uterus was double; the excreta were voided through a cloaca; and the eye was protected by a third eyelid or nictitating mem- brane. At a still earlier period the progenitors of man must have been aquatic in their habits; for morjAology plainly tells us that our lungs consist of a modified swim-bladder, which once served as a float. The clefts on the neck in the embryo of man show where the branchiss once existed. In the lunar or weekly re- current periods of some of our functions we apparently still retain traces of our primordial birthplace, a shore washed by the tides. At about this same early period the true kidneys were replaced by the corpora wolffiana. The heart existed as a simple pulsating vessel; and the chorda dorsalis took the place of a vertebral column. These early ancestors of man, thus seen in the dim recesses of time, must have been as simply, or even still more simply organised than the lancelet or amphioxus. There is one other point deserving a fuller notice. It has long been known that in the vertebrate kingdom one sex bears rudiments of various accessory parts, appertaining to the re- productive system, which properly belong to the opposite sex ; and it has now been ascertained that at a very early embryonic period both sexes possess true male and female glands. Hence some remote progenitor of the whole vertebrate kingdom appears to have been hermaphrodite or androgynous.^*^ But here we encounter a singular difficulty. In the mammalian class the males possess rudiments of a uterus with the adjacent passage, in their vesiculse prostaticse ; they bear also rudiments of mammae, and some male Marsupials have traces of a marsupial sack.^^ Other analogous facts could be added. Are we, then, to suppose that some extremely ancient mammal continued andro- gynous, after it had acquired the chief distinctions of its class, and therefore after it had diverged from the lower classes of the vertebrate kingdom ? This seems very improbable, for we have to look to fishes, the lowest of all the classes, to find any still existent androgynous forms.'-^^ That various accessory parts, -^ This is the conclusion of Prof. *' brata a]-e, in their early condition. Gegenbaur, one of the highest au- " hermaphrodite." Similar views thorities in comparative anatomy; have long been held by som« authors, sec'Grundziigeder vergleich. Anat.' though until recently without a 1870, s. 876. The result has been firm basis. arrived at chiefly from the study of ^^ The male Thylacinus offers the the Amphibia; but it appears from best instance. Owen, 'Anatomy of the researches of Waldeyer. (as Vertebrates,' vol. iii. p. 771. quoted in 'Journal of Anat. and ^^ Hermaphroditism has been ob- Phys.' 1869,^ p. 161), that the sexual served in several species of Serranus, oriT-ms of even "the higher verte- as well a^ in some other fishes, 1 62 The Descent of Man. Pakt I. proper to each sex, are found in a rudimentary condition in the opposite sex, may he explained by such organs having been gradually acquired by the one sex, and then transmitted in a more or less imperfect state to the other. When we treat of sexual selection, we shall meet with innumerable instances of this form of transmission, — as in the case of the spurs, plumes, and brilliant colours, acquired for battle or ornament by male birds, and inherited by the females in an imperfect or rudimentary condition. The possession by male mammals of functionally imperfect mammary organs is, in some respects, especially curious. The Monotremata have the proper milk-secreting glands with orifices, but no nipples ; and as these animals stand at the very base of the mammalian series, it is probable that the progenitors of the class also had milk-secreting glands, but no nipples. This conclusion is supported by what is known of their manner of development ; for Professor Turner informs me, on the authority of Kolliker and Langer, that in the embryo the mammary glands can be distinctly traced before the nipples are in the least visible; and the development of successive parts in the indi- vidual generally represents and accords with the development of successive beings in the same line of descent. The Marsupials differ from the Monotremata by possessing nipples; so that probably these organs were first acquired by the Marsupials, after they had diverged from, and risen above, the Monotremata, and were then transmitted to the placental mammals.^^ No one will suppose that the Marsupials still remained androgynous after they had approximately acquired their present structure. How then are we to account for male mammals possessing mammae ? It is possible that they were first developed in the females and then transferred to the males ; but from what follows this is hardly probable. where it is either normal and sym- delle Scienze,' Bologna, Doc. 28, metrical, or abnormal and uni- 1871) that eels ai-e androgynous, lateral. Dr. Zouteveen has given ^^ Prof. Gegenbaur has shewn me references on this subject, more (* Jenaische Zeitschrift,' Bd. vii. p. especially to a paper by Prof Hal- 212) that two distinct types of bertsma, in the ' Transact, of the nipples prevail throughout the Dutch Acad, of Sciences,' vol. xvi. several mammalian orders, but Dr. Giinther doubts the fact, but that it is quite intelligible how both it has now been recorded by too could have been derived from the many good observers to be any nipples of the Marsupials, and the longer disputed. Dr. M. Lessona latter from those of the Monotre- writes to me, that he has veri- mata. See, also, a memoir by Dr. fied the observations made by Max Huss, on the mammary glands, Cavolini on Serranus. Prof Ereo- ibid. B. viii. p. 176. lani has recently shewn (' Accad. Chap. VI. Affinities and Genealogy. 163 It may be suggested, as another view, that long after the progenitors of the whole mammalian class had ceased to be androgynous, both sexes yielded milk, and thus nourished their young ; and in the case of the Marsupials, that both sexes carried their young in marsupial sacks. This will not appear altogether improbable, if we reflect that the males of existing syngnathous fishes receive the eggs of the females in their abdominal pouches, hatch them, and afterwards, as some believe, nourish the young ;^ — that certain other male fishes hatch tlie eggs within their mouths or branchial cavities ; — that certain male toads take the chaplets of eggs from the females, and wind them round their own thighs, keeping them there until the tad])oles are born ; — that certain male birds undertake the whole duty of incubation, and that male pigeons, as well as the females, feed their nestlings with a secretion from their crops. But the above suggestion first occurred to me from the mammary glands of male mammals being so much more perfectly developed than the rudiments of the other accessory reproductive parts, which are found in the one sex though proper to the other. The mammary glands and nipples, as they exist in male mammals, can indeed hardly be called rudimentary ; they are merely not f Lilly developed, and not functionally active. They are sympa- thetically affected under the influence of certain diseases, like the same organs in the female. They often secrete a few drops of milk at birth and at puberty : this latter fact occurred in the curious case, before referred to, where a young man possessed two pairs of mammae. In man and some other male mammals these organs have been known occasionally to become so well developed during maturity as to yield a fair supply of milk. Now if we suppose that during a former prolonged jDcriod male mammals aided the females in nursing their offspring,^^ and that afterwards from some cause (as from the production of a smaller number of young) the males ceased to give this aid, disuse of the organs during maturity would lead to their becoming inactive ; and from two well-known principles of inheritance, this state of inactivity would probably be transmitted to the males at the corresponding age of maturity. But at an earlier age these '° Mr. Lockwood believes (ns by Prof. Wyman, in ' Proc. Boston quoted in 'Quart. Journal of Science,' Soc. of Nat. Hist.' Sept. 15,1857; April, 1868, p. 269), from what he also Prof. Turner, in 'Journal of has observed of the development of Anat. and Phys.' Nov. 1, 186(3, p. Hippocampus, that the walls of the 78. Dr. Giinther has likewi.se de- abdominal pouch of the male in scribed similar cases, some way aflbrd nourishment. On '' Madlle. C. Pvoyer has suggested male fishes hatching the ova in their a similar view in her ' Origine de mouths, see a very interesting paper I'Homme,' (S:c., 1870. 1 64 The Descent of Man. Part I. organs would be left unaffected, so that they would be almost equally well developed in the young of both sexes. Conclusion. — Yon Baer has defined advancement or progress in the organic scale better than any one else, as resting on the amount of differentiation and specialisation of the several parts of a being, — when arrived at maturity, as I should be inclined to add. Now as organisms have become slowly adapted to diver- sified lines of life by means of natural selection, their parts will have become more and more differentiated and specialised for various functions, from the advantage gained by the division of physiological labour. The same part appears often to have been modified first for one purpose, and then long afterwards for some other and quite distinct purpose ; and thus all the parts are rendered more and more complex. But each organism still retains the general type of structure of the progenitor from which it was aboriginally derived. In accordance with this view it seems, if we turn to geological evidence, that organisa- tion on the whole has advanced throughout the world by slow and interrupted steps. In the great kingdom of the Vertebrata it has culminated in man. It must not, however, be supposed that groups of organic beings are always supplanted, and dis- appear as soon as they have given birth to other and more perfect groups. The latter, though victorious over their pre- decessors, may not have become better adapted for all places in the economy of nature. Some old forms appear to have survived from inhabiting protected sites, where they have not been exposed to very severe competition ; and these often aid us in constructing our genealogies, by giving us a fair idea of former and lost populations. But we must not fall into the error of looking at the existing members of any lowly-organised group as perfect representatives of their ancient predecessors. The most "ancient progenitors in the kingdom of the Vertebrata, at which we are able to obtain an obscure glance, apparently consisted of a group of marine animals,^^ resembling the larvae of existing Ascidians. These animals probably gave rise to a 3^ The inhabitants of the sea- ditions for many generations, can .shore must be greatly affected by hardly fail to run their course in the tides; animals living either regular weekly periods. Now it is a aboixt the mean high-water marlv, mysterious fact that in the higher or about the mean low-water mark, and now terrestrial Vertebrata, as pass through a complete cycle of well as in other classes, many nor- tidal changes in a fortnight. Con- mal and abnormal processes have sequently, their food supply will one or more whole weeks as their undergo marked changes week by periods ; this would be rendered week. The A'ital functions of such intelligible if the Vertebrata are de- animals, living under these con- scended from an animal allied to Chap. VJ, Affinities and Genealogy. 165 group of fishes, as lowly organised as the lancelet ; and from these the Ganoids, and other fishes like the Lcpidosiren, must have been developed. From such fish a very small advance would carry us on to the Amphibians. AYe have seen that birds and reptiles were once intimately connected together ; and the Monotremata now connect mammals with reptiles in a slight degree. But no one can at present say by what line of descent the three higher and related classes, namely, mammals, birds, and reptiles, were derived from the two lower vertebrate classes, namely, amphibians and fishes. In the class of mammals the steps are not difficult to conceive which led from the ancient Monotremata to the ancient Marsupials ; and from these to the early progenitors of the placental mammals. "We may thuy ascend to the Lemuridse ; and the interval is not very wide from these to the Simiadae. The Simiadse then branched off into two great stems, the New World and Old World monkeys ; and from the latter, at a remote period, Man, the wonder and glory of the Universe, i^roceeded. Thus we have given to man a pedigree of prodigious length, but not, it may be said, of noble quality. The world, it has often been remarked, appears as if it had long been preparing for the advent of man : and this, in one sense is strictly true, for he owes his birth to a long line of progenitors. If any single link in this chain had never existed, man would not have been exactly what he now is. Unless we wilfully close our eyes, we may, with our present knowledge, approximately recognise our parentage ; nor need we feel ashamed of it. The most humble organism is something much higher than the inorganic dust under our feet ; and no one with an unbiassed mind can study any living creature, however humble, without being struck with enthusiasm at its marvellous structure and properties. the existing tidal Asoirlians. ^Many cess or function, would not, when instances ot" such periodic processes once gained, be liable to change; might be given, as the gestation of consequently it might be thus trans- mammals, the duration ot" fevers, &c. mitted through almost any number The hatching of eggs affords also a of geneivitions. But if the function good example, for, according to Mr. changed, the period would have to Bartlett (' Land and Water,' Jan. 7, change, and would be apt to change 1871), the eggs of the pigeon are almost abruptly by a whole week, hatched in two weeks ; those of the This conclusion', if sound, is highly fowl in three ; those of the duck in remarkable ; for the period of gesta- four ; those of the goose in five ; tion in each mammal, and the and those of the ostrich in seven hatching of each bird's eggs, and weeks. As far as we can judge, a many other vital processes, thus recurrent period, if approximately betray to us the primordial birth- of the right duration tor any pro- place of these animals. 1 66 The Descent of Man. Tabt I. CHAPTER VII. On the Eaces of Man. The nature and value of specific characters — Application to the races of ii:an — Arguments in favour of, and opposed to, ranking the so-called races of man as distinct species — Sub-species — Monogenists and poly- genists — Convergence of character — Numerous points of resemblance in body and mind between the most distinct races of man — The state of man when he first spread over the earth — Each race not descended from a single pair — The extinction of races — The formation ot races — The effects of crossing — Slight influence of the direct action of the con- ditions of life — Slight or no influence of natural selection — Sexual selection. It is not iny intention here to describe the several so-called races of men ; but I am about to enquire what is the value of the dif- ferences between them under a classificatory point of view, and how they have originated. In determining whether two or more allied forms ought to be ranked as species or varieties, naturalists are practically guided by the following considerations; namely, the amount of difference between them, and whether such differences relate to few or many points of structure, and whether they are of physiological importance ; but more especially whether they are constant. Constancy of character is what is chiefly valued and sought for by naturalists. "Whenever it can be shewn, or rendered probable, that the forms in question have remained distinct for a long period, this becomes an argument of much weight in favour of treating them as species. Even a slight degree of sterility between any two forms when first crossed, or in their offspring, is generally considered as a decisive test of their specific distinctness; and their continued persistence without blending witliin the same area, is usually accepted as sufficient evidence, either of some degree of mutual steiility, or in the case of animals of some mutual repugnance to pairing. Independently of fusion from intercrossing, the complete absence, in a well-investigated region, of varieties linking together any two closely-allied forms, is probably the most important of all the criterions of their specific distinctness ; and this is a somewhat different consideration from mere constancy of character, for two forms may be highly variable and' yet not yield intermediate varieties. Geographical distribution is often brought into play unconsciously and sometimes consciously ; so that forms living in two widely separated areas, in which most Ohap. TIT. The Races of Man, 167 of the other inhabitants are specifically distinct, are themselves usually looked at as distinct ; but in truth this affords no aid in dis- tinguishing geographical races from so-called good or true species. Now let us apply these generally- admitted principles to the races of man, viewing him in the same spirit as a naturalist would any other animal. In regard to the amount of difference between the races, we must make some allowance for our nice powers of discrimination gained by the long habit of observing ourselves. In India, as Elphinstone remarks, although a newly-arrived European cannot at first distinguish the various native races, yet they soon appear to him extremely dissimilar ■} and the Hindoo cannot at first perceive any difference between the several, European nations. Even the most distinct races of man are much more like each other in form than would at first be sup- posed ; certain negro tribes must be excepted, whilst others, as Dr. Eohlfs writes to me, and as I have myself seen, have Caucasian features. This general similarity is well shewn by the French photographs in the Collection Anthropologique du ]\Iuseum de Paris of the men belonging to various races, the greater number of which might pass for Europeans, as many persons to whom I have shewn them have remarked. Neverthe- less, these men, if seen alive, would undoubtedly appear very distinct, so that we are clearly much influenced in our judgment by the mere colour of the skin and hair, by slight differences in the features, and by expression. There is, however, no doubt that the various races, when carefully compared and measured, differ much from each other, — as in the texture of the hair, the relative proportions of all parts of the body,^ the capacity of the lungs, the form and capacity of the skull, and even in the convolutions of the brain.^ But it would be an endless task to specify the numerous points of difference. The races differ also in constitution, in acclimatisation and in liability to certain diseases. Their mental characteristics are likewise very distinct ; chiefly as it would appear in their emotional, but partly in their intellectual faculties. Every one who has had the opportunity of comparison, must have been * 'History of India,' 184-1, vol. i. 'On the capacity of the lungs,' p. 471. p. 323. Father Ripa makes exactly See also the numerous and valuable the same remark with respect to tables, by Dr. Weisbach, fi-om the the Chinese. observations of Dr. Scherzer and 2 A vast number of measure- Dr. Schwarz, in the ' Reise der ments of Whites, Bhicks, and In- Kovara : Anthropolog. Theil,' 1867. dians, are given in the 'Investiga- •* See, for instance, Mr. Marshall's tions in the Military and Anthropo- account of the brain of a Bush- log. Statistics of American Soldiers,' woman, in 'Phil. Transact.' 186-1-, by B. A. Gould, 1869, pp. 298-358 ; p. 519. 1 68 The Descent of Man. Part I. struck with the contrast between the taciturn, even morose, aborigines of S. America and the light-hearted, talkative negroes. There is a nearly similar contrast between the IMalays and the Papuans,* who live under the same physical conditions, and are separated from each other only by a narrow space of sea. We will first consider the arguments which may be advanced in favour of classing the races of man as distinct species, and then the arguments on the other side. If a naturalist, who had never before seen a Negro, Hottentot, Australian, or Mongolian, were to compare them, he would at once perceive that they differed in a multitude of characters, some of slight and some of considerable importance. On enquiry he would find that they were adapted to live under widely different cUmates, and that they differed somewhat in bodily constitution and mental dis- position. If he were then told that hundreds of similar specimens could be brought from the same countries, he would assuredly declare that they were as good species as many to which he had been in the habit of affixing specific names. This conclusion would be greatly strengthened as soon as he had ascertained that these forms had all retained the same character for many centuries ; and that negroes, apparently identical with existing negroes, had lived at least 4000 years ago.^ He would also hear, on the authority of an excellent observer, Dr. Lund,^ that the human skulls 'found in the caves of Brazil, entombed with many extinct mammals, belonged to the same tyj)e as that now pre- vaibng throughout the American Continent. < Wallace, 'The Malay Archi- man (' Races of Man,' 1850, p. 201), pelago,' vol. ii. 1869, p. 178. speaking of young Men?.non (the ^ With respect to the figures in same as Rameses II., as I am in- the famous Egyptian caves of Abou- formed by Mr. Birch), insists in the Simbel, M. Pouchet says ( ' The strongest manner that he is identical Plurality of the Human Races,' Eng. in character with the Jev/s of Ant- translat. 1861:, p. 50), that he was werp. Again, when I looked at the far from finding recognisable repre- statue of Amunoph III., I agreed with sentations of the dozen or more two officers of the establishment, nations which some authors beliere both competent judges, that he had that they can recognise. Even some a strongly marked negro type of of the most strongly-marked races features; but Messrs. Nott and cannot be identified with that de- Gliddon (ibid. p. 146, fig. 53) de- gi"oe of unanimity which might have scribe him as a hybrid, but not of been expected from what has been " negro intermixture." written on the subject. Thus ^ As quoted by Nott and Gliddon, Messrs. Nott and Gliddon ('Types 'Types of Mankind,' 1854, p. 439. of Mankind,' p. 148) state that They give also corroborative evi- Rameses II., or the Great, has dence ; but C. Vogt thinks that the features suped'bly European ; where- subject requires further investiga- as Knox, another firm believer in tion. the specific distinctness of the races of (Jhap. VJI. The Races of Man. 169 Our naturalist would then perhaps turn to geographical dis- tribution, and he would probably declare that those forms must be distinct species, which differ not only in aj^pcarance, but are fitted for hot, as well as damp or dry countries, and for the Arctic regions. He might appeal to the fact that no species in the group next to man, namely the Quadrumana, can resist a low temperature, or any considerable change of climate ; and that the species which come nearest to man have never been reared to maturity, even under the temperate climate of Europe. He would be deeply impressed with the fact, first noticed by Agassiz," that the different races of man are distributed over the world in the same zoological provinces, as those inhabited by undoubtedly distinct species and genera of mammals. This is manifestly the case with the Australian, Mongolian, and Negro races of man ; in a less well-marked manner with the Hottentots; but plainly with the Papuans and Malays, who are separated, as Mr. Wallace has shewn, by nearly the same line which divides the great Malayan and Australian zoological provinces. The Aborigines of America range throughout the Continent ; and this at first appears opposed to the above rule, for most of the productions of the Southern and Northern halves differ widely : yet some few living forms, as the opossum, range from the one into the other, as did formerly some of the gigantic Edentata. The Esquimaux, like other Arctic animals, extend round the whole polar regions. It should be observed that the amount of difference between the mammals of the several zoological provinces does not correspond with the degree of separation between the latter ; so that it can hardly be considered as an anomaly that the Negro differs more, and the American much less from the other races of man, than do the mammals of the African and American continents from the mammals of the other provinces. Man, it may be added, does not appear to have aboriginally inhabited any oceanic island ; and in this respect he resembles the other members of his class. In determining whether the supposed varieties of the same kind of domestic animal should be ranked as such, or as spe- cifically distinct, that is, whether any of them are descended from distinct wild species, every naturalist would lay much stress on the fact of their external parasites being specifically distinct. All the more stress would be laid on this fact, as it would be an exceptional one ; for I am informed by Mr. Denny that the most different kinds of dogs, fowls, and pigeons, in England, are infested by the same species of Pediculi or lice. Now Mr. A. Murray has carefully examined the Pediculi collected in different ' 'Diversity of Origin of the Pluman Races,' in the 'Christian Examiner,' July 1850. I/O The Descent of Man. Tart T. countries from the different races of man ; * and he finds that they differ, not only in coloiir, but in the structure of their claws and limbs. In every case in -svliicli many specimens were obtained the differences were constant. The surgeon of a whaling ship in the Pacific assured me that when the Pediculi, with which some Sandwich Islanders on board swarmed, strayed on to the bodies of the Enghsh sailors, they died in the course of three or four days. These Pediculi were darker coloured, and appeared different from those proper to the natives of Chiloe in South America, of which he gave me Sjoecimens. These, again, appeared larger and much softer than European lice. Mr. Murray procured four kinds from Africa, namely from the Negroes of the Eastern and Western coasts, from the Hottentots and Kaflirs ; two kinds from the natives of Australia ; two from North and two from South America. In these latter cases it may be presumed that the Pediculi came from natives inhabiting different districts. With insects shght structural differences, if constant, are generally esteemed of specific value : and the fact of the races of man being infested by parasites, which appear to be specifically distinct, might fairly be urged as an argument that the races themselves ought to be classed as distinct species. Our supposed naturalist having proceeded thus far in his investigation, would next enquire whether the races of men, when crossed, were in any degree sterile. He might consult the work* of Professor Broca, a cautious and i^bilosophical observer, and in this he would find good evidence that some races were quite fertile together, but evidence of an opposite nature in regard to other races. Thus it has been asserted that the native women of Australia and Tasmania rarely produce children to European men ; the evidence, however, on this head has now been shewn to be almost valueless. The half-castes are killed by the pure blacks : and an account has lately been published of eleven half- caste youths murdered and burnt at the same time, whose remains were found by the police.^'^ Again, it has often been said that when mulattoes intermarry they produce few children; on the other hand, Dr. Bachman of Charleston" positively * 'Transact. R. Soc. of Edinburgh,' who have borne children to a white vol. xxiL 1861, p. 567. man are afterwards sterile with * ' On the Phenomena of Hybridity their own race, is disproved. M. A. m the Genus Homo,' Eng. transhit. de Quatrefages has also collected 1864. (' Revue des Cours Scientifiques,' '" See the interesting letter by March 1869, p. 239) much evidence Mr. T. A. Murray, in the ' Anthro- that Australians and Europeans are polog. Review,' April 1868, p. liii. not sterile when crossed. la this letter Count Strzelecki's *^ ' An Examination of Prof, statement, that Australian women Agassiz's Sketch of the Nat. Pro- Chap. VII. The Races of Man. 17 1 asserts that lie lias known mulatto families wliioli have inter- married for several generations, and have continued on an average as fertile as either pure whites or pure blacks. Enquiries formerly made by Sir C. Lyell on this subject led him, as he informs me, to the same conclusion.'- In the United States the census for the year 1851 included, according to Dr. Bachman, 405,751 mulattoes ; and this number, considering all the circum- stances of the case, seems small ; but it may 2:»art]y be accounted for by the degraded and anomalous position of the class, and by the profligacy of the women. A certain amount of absorption of mulattoes into negroes must always be in progress ; and this would lead to an apparent diminution of the former. The inferior vitality of mulattoes is spoken of in a trustworthy work^^ as a well-known phenomenon ; and this, although a different considera- tion from their lessened fertility, may perhaps be advanced as a proof of the specific distinctness of the jDarent races. No doubt both animal and vegetable hybrids, when j)roduced from extremely distinct species, are liable to premature death; but the parents of mulattoes cannot be put under the category of extremely distinct species. The common Mule, so notorious for long life and vigour, and yet so sterile, shews how little necessary con- nection there is in hybrids between lessened fertility and vitality ; other analogous cases could be cited. Even if it should hereafter be proved that all the races of men were perfectly fertile together, he who was inclined from other reasons to rank them as distinct species, might with justice argue that fertility and sterility are not safe criterions of specific distinctness. We know that these qualities are easily affected by changed conditions of life, or by close inter-breeding, and that they are governed by highly complex laws, for instance, that of the unequal fertility of converse crosses between the same two species. With forms which must be ranked as undoubted species, a perfect series exists from those which are absolutely sterile when crossed, to those which are almost or completely viucesof the Animal World,' Charles- the children are i^^ii and sickly, ton, 1855, p. 44. This belief, as Mr. Reade remarks, ^2 Dr. Rohlt's writes to me that deserves attention, as white men he found the mixed races in the have visited and resided on the Gold Great Sahara, derived from Arabs, Coast for four hundred years, so Berbers, and Negroes of three tribes, that the natives have had ample extraordinarily fertile. On the other time to gain knowledge through hand, Mr. VViuwood Reade informs experience. me that the Negroes ou the Gold '^ ' Military and Anthropolog. Coast, though admiring white men Statistics of American Soldiers,' by and mulattoes, have a maxim that B. A. Gould, 18G9, p. 319. mulattoes should not intermarrv, as 172 The Descent of Man. Part T. fertile. The degrees of sterility do not coincide strictly with the degrees of difference between the parents in external structure or habits of life. Man in many respects may be compared with those animals which have long been domesticated, and a large body of evidence can be advanced in favour of the Pallasian doctrine/* that domestication tends to eliminate the sterility which is so general a result of the crossing of species in a state of nature. From these several considerations, it may be justly urged that the perfect fertility of the intercrossed races of man, if estabnshed, would not absolutely preclude us from ranking them as distinct species. Independently of fertility, the characters presented by the off- spring from a cross have been thought to indicate whether or not the parent-forms ought to be ranked as species or varieties ; but after carefully studying the evidence, I have come to the con- clusion that no general rules of this kind can be trusted. The ordinary result of a cross is the production of a blended or '* ' The Variation of Animals and Plants under Domestication,' vol. ii. p. 109. I may here remind the reader that the sterility of species when crossed is not a specially- acquired quality, but, like the in- capacity of certain trees to be graft- ed together, is incidental on other acquired differences. The nature of these differences is unknown, but they relate more especially to the re- productive system, and much less so to external structure or to ordinary differences in constitution. One important element in the sterility of crossed species apparently lies in one or both having been long habi- tuated to fixed conditions ; for we know that changed conditions have a special influence on the repro- diictive system, and we have good reason to believe (as before re- marked) that the fluctuating con- ditions of domestication tend to eliminate that sterility which is so general with species, in a natural state, when crossed. It has else- where been shewn by me (ibid. vol. ii. p. 185, and 'Origin of Species' 5th edit. p. 317), that the sterility of crossed species has not been ac- quired through natural selection : we can see that when two forms have already been rendered very sterile, it is scarcely possible that their sterility should be augmented by the preservation or survival of the more and more sterile indi- viduals ; for as the sterility in- creases, fewer and fewer offspring will be produced from which to breed, and at last only single in- dividuals will be produced, at the rarest intervals. But there is even a higher grade of sterility than this. Both Gartner and Kolreuter have proved that in genera of plants including many species, a series can be formed from species which when crossed yield fewer and fewer seeds, to species which never pro- duce a single seed, but yet are affected by the pollen of the other species, as shewn by the swelling of the germen. It is here mani- festly impossible to select the more sterile individuals, which have al- ready ceased to yield seeds ; so that the acme of sterility, when the germen alone is affected, cannot have been gained through selection. This acme, and no doubt the other grades of steriiity, are the incidental results of certain unknown differ- ences in the constitution of the re- productive system of the species which are crossed. Chap. Yll. The Races of Man. 173 intermediate form ; but in certain cases some of the ofiFspring take closely after one parent-form, and some after the other. This is especially apt to occur when the parents differ in characters which first appeared as sudden variations or monstrosities.^^ I refer to this point, because Dr. Rohlfs informs me that he has frequently seen in Africa the offspring of negroes crossed with members of other races, either completely black or completely white, or rarely piebald. On the other hand, it is notorious that in America mulattocs commonly present an intermediate appearance. We have now seen that a naturalist might feel himself fully justified in ranking the races of man as distinct species ; for he has found that they are distinguished by many differences in structure and constitution, some being of importance. These differences have, also, remained nearly constant for very long periods of time. Our naturalist will have been in some degree influenced by the enormous range of man, which is a great anomaly in the class of mammals, if mankind be viewed as a single species. He will have been struck w^ith the distribution of the several so-called races, which accords with that of other undoubtedly distinct species of mammals. Finally, he might urge that the mutual fertility of all the races has not as yet been fully proved, and even if proved would not be an absolute proof of their specific identity. On the other side of the question, if our supposed naturalist were to enquire whether the forms of man keep distinct like ordinary species, when mingled together in large numbers in the same country, he would immediately discover that this was by no means the case. In Brazil he w^ould behold an immense mongrel population of Negroes and Portuguese ; in Chiloe, and other parts of South America, he would behold the whole popu- lation consisting of Indians and Spaniards blended in various degrees.^" In many parts of the same continent he would meet with the most complex crosses between Negroes, Indians, and Europeans ; and judging from the vegetable kingdom, such triple crosses afford the severest test of the mutual fertility of the parent-forms. In one island of the Pacific he w^ould find a small population of mingled Polynesian and English blood; and m the Fiji Archipelago a population of Polynesian and Negritos '* ' The Yariatiou of Animals,' success and energy of the Paulistas &c., vol. ii. p. 92. in Brazil, who are a much crossed '* M. de Quatrefages has given race of Portuguose and Indians, with (' Anthropolog. Keview,' Jan. 1869, a mixture of the blood of other p. 22) an interesting account of the races. 1/4 T lie Descent of Man. Part I. crossed in all degrees. Many analogous cases could be be added ; for instance, in Africa. Hence the races of man are not suf- ficiently distinct to inhabit the same country without fusion ; and the absence of fusion affords the usual and best test of si^ecific distinctness. Our naturalist would likewise be much disturbed as soon as he perceived that the distinctive characters of all the races were highly variable. This fact strikes every one on first beholding the negTO slaves in Brazil, who have been imported from all parts of Africa. The same remark holds good with the Polynesians, and with many other races. It may be doubted whether any character can be named which is distinctive of a race and is constant. Savages, even within the limits of the same tribe, are not nearly so uniform in character, as has been often asserted. Hottentot women offer certain peculiarities, more strongly marked than those occurring in any other race, but these are known not to be of constant occurrence. In the several American tribes, colour and hairiness differ considerably; as does colour to a certain degree, and the shape of the features greatly, in the Negroes of Africa. The shape of the skull varies much in some races ;^^ and so it is with every other character. Now all naturalists have learnt by dearly-bought experience, how rash it is to attempt to define species by the aid of inconstant chara,cters. But the most weighty of all the arguments against treating the races of man as distinct si)ecies, is that they graduate into each other, independently in many cases, as far as we can judge, of their having intercrossed. Man has been studied more carefully than any other animal, and yet there is the greatest possible diversity amongst capable judges whether he should be classed as a single species or race, or as two (Virey), as three (Jacquinot), as four (Kant), five (Blumenbach), six (Buffon), seven (Hunter), eight (Agassiz), eleven (Pickering), fifteen (Bory St. Vincent), sixteen (Desmoulins), tw^enty-two (Morton), sixty (Crawfurd), or as sixty-three, according to Burke.^^ This diversity of judgment does not prove that the races ought not to be ranked as sj^ecies, but it shews that they graduate into each ^^ For instance with the abori- ^* See a good discussion on this gines of America and Australia. subject in Waitz, ' Introduct. to Prof. Huxley says (' Transact. Inter- Anthropology,' Eng. translat. 1863, nat. Congress of Prehist. Arch.' pp. 198-208, 227. I have taken 1868, p. 105) that the skulls of some of the above statements from many South Germans and Swiss are H. Tuttle's ' Origin and Antiquity " as short and as broad as those of of Physical Man,' Boston, 1866, p. "the Tartars," &c. 35. Cii^?. VII. The Races of Man. 175 other, and tbat it is hardly possible to discover clear distinctive characters between tliem. Every naturalist who has had the misfortune to undertake the description of a group of highly varying organisms, has en- countered cases (I speak after experience) precisely like that of man ; and if of a cautious disposition, he will end by uniting all the forms which graduate into each other, under a single species ; for he will say to himself that he has no right to give names to objects which he cannot define. Cases of this kind occur in the Order which includes man, namely in certain genera of monkeys; whilst in other genera, as in Cercopithecus, most of the species can be determined with certainty. In the American genus Cebus, the various forms are ranked by some naturalists as species, by others as mere geographical races. Now if numerous sjiecimens of Cebus were collected from all parts of South America, and those forms which at present appear to be specifically distinct, were found to graduate into each other by close steps, they would usually be ranked as mere varieties or races ; and this course has been followed by most naturalists with respect to the races of man. Nevertheless, it must be confessed that there are forms, at least in the vegetable king- dom,'^ which we cannot avoid naming as species, but which are connected . together by numberless gradations, independently of intercrossing. Some naturalists have lately employed the term " sub-species" to designate forms which possess many of the characteristics of true species, but which hardly deserve so high a rank. Now if we reflect on the weighty arguments above given, for raising the races of man to the dignity of species, and the insuperable diffi- culties on the other side in defining them, it seems that the term " sub-species " might here be used with propriety. But from long habit the term *' race " will perhaps always be employed. The choice of terms is only so far imi3ortant in that it is desirable to use, as far as possible, the same terms for the same degrees of difiFerence. Unfortunately this can rarely be done : for the larger genera generally include closely-aUied forms, which can be distinguished only with much difficulty, whilst the smaller genera within the same family include forms that are perfectly distinct ; yet all must be ranked equally as species. So again, species within the same large genus by no means resemble each other to the same degree r on the contrary, some of them ^^ Prof. Nagfli has carefully de- has made analogous remarks on Bcribed several striking cases in his some intermediate forms in the ' Botanische Mittheilungen,' B. ii. Composita; of N. America 18G6, s. 294-369. Prof. Asa Gray 176. The Descent of Man. Part I. can generally be arranged in little groups round other species, like satellites round planets.'^" The question whether mankind consists of one or several species has of late years been much discussed by anthropologists, who are divided into the two schools of monogenists and polygenists. Those who do not admit the principle of evolution, must look at species as separate creations, or as in some manner as distinct entities ; and they must decide what forms of man they will consider as species by the analogy of the method commonly pursued in ranking other organic beings as species. But it is a hopeless endeavour to decide this point, until some definition of the term " species " is generally accepted ; and the definition must not include an indeterminate element such as an act of creation. We might as well attempt without any definition to decide whether a certain number of houses should be called a village, town, or city. "We have a practical illustration of the diflBcultyin the never-ending doubts whether many closely-allied mammals, birds, insects, and plants, which represent each other respectively in North America and Europe, should be ranked as species or geographical races ; and the like holds true of the productions of many islands situated at some little distance from the nearest continent. Those naturalists, on the other hand, who admit the principle of evolution, and this is now admitted by the majority of rising men, will feel no doubt that all the races of man are descended from a single primitive stock ; whether or not they may think fit to designate the races as distinct species, for the sake of ex- pressing their amount of difference. ^^ With our domestic animals the question whether the various races have arisen from one or more species is somewhat different. Although it may be admitted that all the races, as well as all the natural species within the same genus, have sprung from the same primitive stock, yet it is a fit subject for discussion, whether all the domestic races of the dog, for instance, have acquired their present amount of difference since some one species was first domesticated by man ; or whether they owe some of their characters to inheritance from distinct species, which had already been differentiated in a state of nature. With man no such question can arise, for he cannot be said to have been domesticated at any particular period. During an early stage in the divergence of the races of man 20 < Origin of Species,' 5th edit, in the ' Fortnightly Review,' 18G5 p. 68. p. 275. *• See Prof. Huxley to this effect Chap. VII. The Races of Man. lyj from a coramon stock, tlie differences between the races and their number must have been small ; consequently as far as their distinguishing characters are concerned, they tht n had less claim to rank as distinct species than the existing so-called races. Nevertheless, so arbitrary is the term of species, that such early races would perhaps have been ranked by some naturalists as distinct species, if their differences, although extremely slight, had been more constant than they are at present, and had not graduated into each other. It is however possible, though far from probable, that the early progenitors of man might formerly have diverged much in character, until they became more unlike each other than any now existing races; but that subsequently, as suggested by Vogt," they converged in character. "When man selects the off- spring of two distinct species for the same object, he sometimes induces a considerable amount of convergence, as far as general appearance is concerned. This is the case, as shewn by Von Nathusius,-^ with the improved breeds of the pig, which are descended from two distinct species; and in a less marked manner with the improved breeds of cattle. A great anatomist, Gratiolet, maintains that the anthropomorphous apes do not form a natural sub-group ; but that the orang is a highly developed gibbon or semnopithecus, the chimpanzee a highly developed macacus, and the gorilla a highly developed mandrill. If this conclusion, which rests almost exclusively on brain - characters, be admitted, w^e should have a case of convergence at least in external characters, for the anthropomorphous apes are certainly more like each other in many points, than they are to other apes. All analogical resemblances, as of a whale to a fish, may indeed be said to be cases of convergence; but this term has never been applied to superficial and adaptive resem- blances. It would, however, be extremely rash to attril)ute to convergence close similarity of character in many points of structure amongst the modified descendants of widely distinct beings. The form of a crystal is determined solely by the mole- cular forces, and it is not surprising that dissimilar substances should sometimes assume the same form ; but with organic beings we should bear in mind that the form of each depends on an infinity of complex relations, namely on variations, due to causes far too intricate to be followed,— on the nature of the variations preserved, these depending on the physicial condi- ^- ' Lectures oa ^lan,' Eng. trans- schichte, &c., Schweineschildel,' lat. 186+, p. 4fi8. 1864, s. 104. With respect to cattle, 23 ' Die Racen des Schwcines,' see M. de Quatretages, ' Unit<5 de I860, s. 46. 'Voistudien fiir Ge- I'Espece Humaine,' 1861, p. 119. 178 The Descent of Man, Part 1. tions, and still more on the surrounding organisms which com- pete with each,— and lastly, on inheritance (in itself a fluctuating element) from innumerable progenitors, all of which have had their forms determined through equally complex relations. It appears incredible that the modified descendants of two organ- isms, if these differed from each other in a marked manner, should ever afterwards converge so closely as to lead to a near approach to identity throughout their whole organisation. In the case of the convergent races of pigs above referred to, evi- dence of their descent from two primitive stocks is, according to Von Nathusius, still plainly retained, in certain bones of their skulls. If the races of man had descended, as is supposed by some naturalists, from two or more species, which differed from each other as much, or nearly as much, as does the orang from the gorilla, it can hardly be doubted that marked differences in the structure of certain bones would still be discoverable in man as he now exists. Although the existing races of man differ in many respects, as in colour, hair, shape of skull, proportions of the body, &c., yet if their whole structure be taken into consideration they are found to resemble each other closely in a multitude of points. Many of these are of so unimportant or of so singular a nature, that it is extremely improbable that they should have been inde- pendently acquired by aboriginally distinct species or races. The same remark holds good with equal or greater force with respect to the numerous points of mental similarity between the most distinct races of man. The American aborigines, Negroes and Europeans are as different from each other in mind as any three races that can be named; yet I was incessantly struck, whilst living with the Fuegians on board the " Beagle," with the many little traits of character, shewing how similar their minds were to ours ; and so it was with a full-blooded negro with whom I happened once to be intimate. He who will read Mr. Tylor's and Sir J. Lubbock's interesting works ^^ can hardly fail to be deeply impressed with the close similarity between the men of all races in tastes, dispositions and habits. This is shewn by the pleasure which they all take in dancing, rude music, acting, painting, tattooing, and otherwise decorating themselves ; in their mutual comprehension of gesture- language, by the same expression in their features, and by the same inarticulate cries, when excited by the same emotions. This similarity, or rather identity, is striking, when contrasted ^* Tylor's ' Early History of Man- language, see p. 54. Lubbock's kind,' 1865 : with respect to gesture- ' Prehistoric T'mes,' 2nd edit. 1869. Chap. VI r. TJie Races of Man. 179 with the different expressions and erics made by distinct species of monkeys. There is good evidence that tlie art of sliooting with bows and arrows has not been lianded down from any common progenitor of mankind, yet as Westroi)p and Nilsson have remarked/^ the stone arrow-heads, brought from the most distant parts of the world, and manufactured at the most remote periods, are almost identical ; and this fact can only be accounted for by the various races having similar inventive or mental powers. The same observation has been made by archaeologists ^^ with respect to certain widely-prevalent ornaments, such as zig- zags, &c. ; and with respect to various simple beliefs and cus- toms, such as the burying of the dead under megalithic struc- tures. I remember observing in South America,^^ that there, as in so many other parts of the world, men have generally chosen the summits of lofty hills, to throw uj) piles of stones, either as a record of some remarkable event, or for burying their dead. Now when naturalists observe a close agreement in numerous small details of habits, tastes, and dispositions between two or more domestic races, or between nearly-allied natural forms, they use this fact as an argument that they are descended from a common progenitor who was thus endowed ; and consequently that all should be classed under the same species. The same argument may be applied with much force to the races of man. As it is improbable that the numerous and unimportant points of resemblance between the several races of man in bodily struc- ture and mental faculties (I do not here refer to similar customs) should all have been independently acquired, they must have been inherited from progenitors who had these same characters. We thus gain some insight into the early state of man, before he had spread step by step over the face of the earth. The spreading of man to regions widely separated by the sea, no doubt, pre- ceded any great amount of divergence of character in the several races ; for otherwise we should sometimes meet with the same race in distinct continents ; and this is never the case. Sir J. Lubbock, after comparing the arts now practised by savages in all parts of the world, sjDecifies those which man could not have known, when he first wandered from his original birth-place ; for if once learnt they would never have been forgotten.'-** He 2^ 'On Analogous Forms of Im- 'Journal of Ethnological Soc' as plenients,' in 'Memoirs of Anthropo- given in * Scientific Opinion,' June log. Soc.,' by H. M. Westropp. 'The 2ud, 1869, p. 3. Primitive Inhabitants of Scandi- ^^ 'Journal of Researches: Voyage navia,' Eng. transFat. edited by Sir of the "Beagle,"' p. 46. J. Lubbock, 1868, p. 104-. "-* 'Prehistoric Times,' 1809, p. 2« Westropp, ' On CDmlechs/ &c., 574. l8o The Descent of Man. Part I. tlms shews that " the spear, which is but a development of the " knife-point, and the club, which is but a long hammer, are the " only things left." He admits, however, that the art of making- lire probably had been already discovered, for it is common to all the races now existing, and was known to the ancient cave- inhabitants of Europe. Perhaps the art of making rude canoes or rafts was likewise known; but as man existed at a remote epoch, when the land in many places stood at a very different level to what it does now, he would have been able, without the aid of canoes, to have spread widely. Sir J. Lubbock further remarks how improbable it is that our earliest ancestors could have " counted as high as ten, considering that so many races "now in existence cannot get beyond four." Nevertheless, at this early p)eriod, the intellectual and social faculties of man could hardly have been inferior in any extreme degree to those possessed at present by the lowest savages ; otherwise primeval man could not have been so eminently successful in the struggle for life, as proved by his early and wide diffusion. From the fundamental differences between certain languages, some philologists have inferred that when man first became widely diffused, he was not a speaking animal ; but it may be suspected that languages, far less perfect than any now spoken, aided by gestures, might have been used, and yet have left no traces on subsequent and more highly-developed tongues. With- out the use of some language, however imperfect, it appears doubtful whether man's intellect could have risen to the standard implied by his dominant position at an early period. "Whether primeval man, when he possessed but few arts, and those of the rudest kind, and when his power of language was extremely imperfect, would have deserved to be called man, must depend on the definition wliich we employ. In a series of forms graduating insensibly from some ape-like creature to man as he now exists, it would be impossible to fix on any definite point when the term " man " ought to be used. But this is a matter of very little importance. So again, it is almost a matter of indifference whether the so-called races of man are thus designated, or are ranked as species or sub-species ; but the latter term apj^ears the more appropriate. Finally, we may conclude that when the principle of evolution is generally accepted, as it surely will be l3efore long, the dispute between the monogenists and the poly- genists will die a silent and unobserved death. One other question ought not to be passed over without notice, namely, whether, as is sometimes assumed, each sub-sj)ecies or race of man has sprung from a single pair of progenitors. With Chap. VII. TJie Extinction of Races. 1 8 1 oui* domestic animals a new race can readily be formed by care- fully matching the varying ofiFspring from a single pair, or even from a single individual possessing some new character; but most of our races have been formed, not intentionally from a selected pair, but unconsciously by the preservation of many in- dividuals which have varied, however slightly, in some useful or desired manner. If in one country stronger and heavier horses, and in another country lighter and fleeter ones, were habitually preferred, we may feel sure that two distinct sub-breeds would be produced in the course of time, without any one pair having been separated and bred from, in either country. Many races have been thus formed, and their manner of formation is closely analogous to that of natural species. We know, also, that the horses taken to the Falkland Islands have, during successive generations, become smaller and weaker, whilst those which have run wild on the Pampas have acquired larger and coarser heads ; and such changes are manifestly due, not to any one pair, but to all the individuals having been subjected to the same conditions, aided, perhaps, by the principle of reversion. The new sub- breeds in such cases are not descended from any single pair, but from many individuals which have varied in different degrees, but in the same general manner ; and we may conclude that the races of man have been similarly produced, the modifications being either the direct result of exposure to different conditions, or the indirect result of some form of selection. But to this latter subject we shall presently return. On the Extinction of the Eacesof Man. — The partial or complete extinction of many races and sub-races of man is historically known. Humboldt saw in South America a parrot which was the sole living creature that could speak a word of the language of a lost tribe. Ancient monuments and stone implements found in all parts of the world, about which no tradition has been ])reserved by the present inhabitants, indicate much extinction, Some small and broken tribes, remnants of former races, still survive in isolated and generally mountainous districts. In Europe the ancient races were all, according to Schaaffhausen,-" " lower in the scale than the rudest living savages ;" they must therefore have differed, to a certain extent, from any existing race. The remains described by Professor Broca from Les Eyzies, though they unfortunately appear to have belonged to a single family, indicate a race with a most singular combination of low or simious, and of high characteristics. This race is " entirely' 29 Translation in 'Anthropological Review,' Oct. 1868, p. 431 1 82 The Descent of Man. Part I. " different from any other, ancient or modern, that we have ever "heard of."^° It differed, therefore, from the quaternary race of the caverns of Belgium. Man can long resist conditions which appear extremely un- favourable for his existence.^^ He has long lived in the extreme regions of the North, with no wood for his canoes or implements, and with only blubber as fuel, and melted snow as drink. In the southern extremity of America the Fuegians survive with- out the protection of clothes, or of any building worthy to be called a hovel. In South Africa the aborigines wander over arid plains, where dangerous beasts abound. Man can withstand the deadly influence of the Terai at the foot of the Himalaya, and the pestilential shores of tropical Africa. Extinction follows chiefly from the competition of tribe with tribe, and race with race. Various checks are always in action, serving to keep down the numbers of each savage tribe, — such as periodical famines, nomadic habits and the consequent deaths of infants, prolonged suckling, wars, accidents, sickness, licen- tiousness, the stealing of women, infanticide, and especially lessened fertility. If any one of these checks increases in power, even slightly, the tribe thus aft'ected tends to decrease ; and when of two adjoining tribes one becomes less numerous and less powerful than the other, the contest is soon settled by war, slaughter, cannibalism, slavery, and absorption. Even when a weaker tribe is not thus abruptly swept away, if it once begins to decrease, it generally goes on decreasing until it becomes extinct.^^ When civilised nations come into contact with barbarians the struggle is short, except where a deadly climate gives its aid to the native race. Of the causes which lead to the victory of civilised nations, some are plain and simple, others complex and obscure. We can see that the cultivation of the land will be fatal in many ways to savages, for they cannot, or will not, change their habits. New diseases and vices have in some cases proved highly destructive; and it appears that a new disease often causes much death, until those who are most susceptible to its destructive influence are gradually weeded out f^ and so it may be with the evil effects from spirituous liquors, as well as with the unconquerably strong taste for them shewn by so many ^^ 'Transact, Internat. Congress terben der NatuvA^olker,' 1868, s. 82. of Prehistoric Arch,' 1868, pp. 172- ^^ Gerland (ibid. s. 12) gives facts • 175. See also Broca (translation) in support of this statement. in ' Anthropological Review,' Oct. ^^ See remarks to this effect in 1868, p. 410. Sir H. Holland's ' Medical Notes and 31 Dr. Gerland ' Ueber das Auss- Reflections,' 1839, p. 390. Chap. VI [. The Extinction of Races. 1S3 savages. It further appears, mysterious as is the fact, that the first meeting of distinct and separated people generates disease.^^ Mr. Sproat, wlio in Vancouver Island closely attended to the subject of extinction, believed that changed habits of life, consequent on the advent of Europeans, induces much ill health. He lays, also, great stress on the apparently trifling cause that the natives become '' bewildered and dull by the new life around " them ; they lose the motives for exertion, and get no new ones " in their place." ^^ The grade of their civilisation seems to be a most important element in the success of competing nations. A few centuries ago Europe feared the inroads of Eastern barbarians ; now any such fear would be ridiculous. It is a more curious fact, as Mr. Bagehot has remarked, that savages did not formerly waste away before the classical nations, as they now do before modern civilised nations; had they done so, the old moralists would have mused over the event ; but there is no lament in any writer of that period over the perishing barbarians.^^ The most po- tent of all the causes of extinction, appears in many cases to be lessened fertility and ill-health, especially amongst the children, arising from changed conditions of life, notwithstanding that the new conditions may not be injurious in themselves. I am much indebted to Mr. H. H. Howorth for having called my attention to this suliject, and for having given me information respecting it. I have collected the following cases. When Tasmania was first colonised the natives were roughly estimated by some at 7000 and by others at 20,000. Their number was soon greatly reduced, chiefly by fighting with the English and with each other. After the famous hunt by all the colonists, when the remaining natives delivered themselves up to the government, they consisted only of 120 individuals,^'^ who were in 18o2 transported to Flinders Island. This island, situated between Tasmania and Australia, is forty miles long, and from twelve to eighteen miles broad: it seems healthy, and the natives were well treated. Nevertheless, they suffered greatly in health. In 1834 they consisted (Bon wick, p. 250) of forty-seven adult males, forty-eight adult females, and sixteen children, or in all of 111 souls. In 1835 only one hundred were left. " I have collected ('Journal of Savage Life,' 18G8, p. 284-. Researches, Voyage of the "Beagle,"' ^'^ Bagehot, ' I'hysics and Poli- p. 435) a good many cases bearing tics,' ' Fortnightly Review,' April on this subject: see also Geriand, 1, 18 in them. Every principal gyrus and sulcus of a chim])anzee's bram is ( h arly rcpiesentLd in that of a man, so that the terminology which ajjpHcs to the one answers lor the other. On this point there is no ditlVrenrc of opinion. Some years since, Professor Bischoff published a memoir '" on the C('rebral convolutions of man and apes; and as the ptupnse of my learned colleague was certainly not to diminish the value of the *" 'Die Gi'osshirn-Wmdungen des Menschen ;' ' AbhaQJluugea dev K, Bayerischeu Akademie.* Bd. x., 18G8. 200 • The Descent of Man. Part 1. differences between apes and men in this respect, I am glad to make a citation from him. " That the apes, and especially the orang, chimpanzee and gorilla, " come very close to man in their organisation, much nearer than to any " otlier animal, is a well known fact, disputed by nobody. Looking at " the matter from the point of view of organisation alone, no one probably " would ever have disputed Ihe view of Linnaeus, that man should be " placed, merely as a peculiar species, at the hs ad of the mammalia and of *' those apes. Both shew, in all their organs, so close an affinity, that the " most exact anatomical investigation is needed in order to demonstrate " those differences which really exist. So it is with the brains. The " brains of man, the orang, the chimpanzee, the gorilla, in spite of all '' the important differences which they present, cume very close to one " another ' (1. c. p. 101). Tiiere remains, then, no dispute as to the resemblance in fundamental characters, between the ape's brain and man's ; nor any as to the won- derfully close similarity between the chimpanzee, orang and man, in even the details of the arrangement of the gyri and sulci of the cerebral hemispheres. Nor, turning to the differences between the brains of the highest apes and that of man, is there any serious question as to the nature and extent of these differences. It is admitted that the man's cerebral hemispheres are absolutely and relatively larger than those of the orang and chimpanzee ; that his frontal lobes are less excavated by the upward protrusion of the roof of the orbits ; that his gyri and sulci are. as a rule, less symmetrically disposed, and present a greater num^jer of secondary plications. And it is admitted that, as a rule, in man, the temporo-occipital or "external perpendicular" fissure, which is usually so strongly marked a feature of the ape's brain is but faintly marked. But it is also clear, that none of these differences constitutes a sharp demarcation between the man's and the ape's brain. In respect to the external perpendicular fissure of Gratiolet, in the human brain, for instance. Professor Turner remarks :'^ " In some brains it appears simply as an indentation of the margin of " the hemisphere, but, in others, it extends for some distance more or less " transversely outwards. I saw it in the right hemisphere of a female " brain pass more than two inches outwards ; and in another specimen, " also the right hemisphere, it proceeded for four-tenths of an inch out- " wards, and then extended downwards, as far as the lower margin of the " outer smface of the hemisphere. The imperfect definition of this fissure " in the majority of human brains, as compared with its remarkable dis- " tinctness in the brain of most Quadrumana, is owing to the presence, in " the former, of certain superficial, well marked, secondary convolutions " which bridge it over and connect the parietal with the occipital lobe. " The closer the first of these bridging gyri lies to the longitudinal " fissure, the shorter is the external parieto-occipital fissure." (1. c p. 12.) The obliteration of the external perpendicular fissure of Gratiolet, therefore, is not a constant character of the human brain. On the other hand, its full development is not a. constant character of the higher ape's brain. For, in the chimpanzee, the more or less extensive oblitera- tion of the exteraal perpt-mUeular sulcus by " bridging convolutions," on one side or the other, has been noted over and over again bv Prof '* 'Convolutions of the Human Cerebrum Topographically Considered, 1866, p. 12. Chap. VII. Siriictiire of the Brain. 20 1 Rolleston, Mr. Marshall, -M. Brora and Professor Turner. At the conclusion of a special paper on this subject the latter writes :' - •' The three specimens of the brain of a chimpanzee just described, *' prove, that the generalisation which Gratiolet has attempted to draw of " the complete absence of the first ccmnecting convolution and the " concealment of the second, as essentially characteristic features in th(; " brain of this animal, is by no means universally applicable. In only one " specimen did the brain, in these particulars, follow the law which " Gratiolet has expressed. As regards the presence of the su])eriur britlg- " ing convolution, I am inclined to think that it has existed in one hemi- " sphere, at least, in a majority of the brains of this animal which have, up " to this time, been figured or described. The superficial position of the " second bridging convolution is evidently less frequent, and has as yet, •' I believe, only been seen in the brain (A) recorded in this communi- " cation. The asymmetrical arrangement in the convolutions of the " two hemispheres, which previous observers have referred to in their " descriptions is also well illustrated in these specimens." (pp. 8, 9.) Even were the presence of the temporo-occipital, or external per- pendicular, sulcus a mark of distinction between the higher apes an 1 man, the value of such a distinctive character would be rendered very doubtful by the structure of the brain in the Piatyrhine apes. In fact wliile the temporo-occipital is one of the most con.-itant of sulci in the Catarhine, or Old World, apes, it is never very strongly developed in the New World apes ; it is absent in the smaller Platyrhini ; rudimentary in Tithecia ;" and more or less obliterated by bridging convolutions in Ateles. A character which is thus variable within the limits of a single group cfin have no great taxouomic value. It is further established, that the degree of asymmetry of the convolu- tion of the two sides in the human brain is subject to nnieh individual variation,; and that, in those individuals of the Bushman race who have been examined, the gyri and sulci of the two hemispheres are consider- ably less complicated and more symmetrical than in the European brain, while, in some individuals of the chimpanzee, their complexity and asymmetiy become notable. This is particularly tlie case in the brain of a young male chimpanzee figured by M. Broca. (' Lorch-e des Primates," p. 165, fig. 11.) Again, as respects the question of absolute size, it is established that the difterence between the largest and the smallest healtiiy human brain is greater than the ditference between the smallest healthy human brain and the largest chimpanzees or orang's brain. Moreover, there is one circumstance in which the orang's and chim- panzee's brains resemble man's, but in which they ditter from the lower apes, and that is the presence of two corpora candicantia — the t'ynomorpha having but one. In view of these facts I do not hesitate in this year 1874, to repeat and insist upon the proptjsition which I inundated in ISGS.^'' " So far as cerebral structure goes, therefore, it is clear that man " Notes more especially on the " Flower 'On the Anatomy of bridging convolutions in the Brain I'ithecia Monackns,'' ' I'roceedings of of the Chimpanzee, 'Proceedings of the 2lk)ol<)gical Society,' 18G2. the Royal Society of Edinburgh,' '* ' Man's Place in Nature,' p. 102. 1865-6. 10 202 The Descent of Man. Part L " diffirs less from the chimpanzee or the orang, than these do even "from the monkeys, and that the diflference between the brain of the "•chimpanzee and of man is almost insignificant, when compared with "that between the chimpanzee brain and that of a Lemur." In the paper to which I have referred, Professor Bischofif does not deny tlie second part of this statement, but he first makes the irrelevant remark that it is not wonderful if the brains of an orang and a Lemur are very different ; and secondly, goes on to assert that, " If we succes- " sively compare the brain of a man with that of an orang ; the brain of " this with that of a chimpanzee ; of this with that of a "orilla, and so "on of a Hylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, " Cehus, Callithrix, Lemur, Stenops, Hapale, we shall not meet with a " greater, or even as great a, break in the degree of development of the "convolutions, as we find between the brain of a man and that of au " orang or chimpanzee." To which I reply, firstly, that whether this assertion be true or false, it has nothing whatever to do with the proposition enunciated in 'Man's Place in Nature,' which refers not to the development of the convolutions alone, but to the structure of the whole brain. It Professor Bischoff had taken the trouble to refer to p. 96 of the work he criticises, in fact, he would have found the following passage: "And it is a " remarkable circumstance that though, so far as our present know- ■ " ledge extends, there is one true structural break in the series of forms " of Simian brains, this hiatus does not lie between man and the " manlike apes, but between the lower and the lowest Simians, or in " other words, between the Old and New World apes and monkeys and " the Lemurs. Every Lemur which has yet been examined, in fact, " has its cerebellum partially visible from above; and its posterior lobe, " with the contained posterior cornu and hippocampus minor, moie or "less rudimentary. Every marmoset, American monkey, Old World " monkey, baboon, or manlike ape, on the contrary, has its cerebellum " entirely hidden, posteriorly, by the cerebral lobes, and possesses a " large posterior cornu with a well-developed hippocampus minor." This statement was a strictly accurate account of what w^as known when it was made; and it does not appear to me to be more than apparently weakened by the subsequent discovery of the relatively small development of the posterior lobes in the Siamang and in the Howling monkey. Notwithstanding the exceptional brevity of the posterior lobes in these two species, no one will pretend that their brains, in the slightest degree, approach those of the Lemurs. And if, instead of putting Hapale out of its natural place, as Professor Bischoff most unaccountably does, we write the series of animals he has chosen to mention as follows : Homo, Pithecus, Troglodytes, Hylobates, Semnopithecus, Cynocephalus, CercopWieeus, Macacus, Cebus, Callithrix, Hapale, Lemur, Stenops, I venture to reaffirm that the great break in this series lies between Hapale and Lemur, and that tills break is considerably greater than that between any other two terms of that series. Professor Bischoff" ignores the fact that long before he wrote, Gratiolet had suggested the separation of the Lemurs from the other Primates on the very ground of the difference in their cerebral characters ; and that Professor Flower had made the following observations in the course of his description of the brain of the Javan Lor is J ^ '^ 'Transactions of the Zoological Society,' vol. v. 1862. (JHAP. VII. Structure of the Brain. 203 "And it is especially remarkable that, in the development of the " posterior lobes, there is no approximation to the Leinurine, short "hemisphered, brain, in those monkeys which are commonly supposed '• to approach this family in other respects, viz., the lower members of " tlie Fiatyrhine gronp." So far as the structure of the adult brain is concerned, then, the very considerable additions to oar knowledge, which have been made by the researches of so many investigators, during tlie past ten years, fully justify the statement which I made in 1SG3. But it has been said that, admitting the similarity between the adult brains of man and apes, they are nevertheless, in reality, widely diiFerent, because th( y exhibit fundamental dilierences in the mode of their development. No one would be more ready tlian I to admit the force of this argument, if 8uch fundamental diiierenccs of development really exist, liut I deny that they do exist. On the contrary, there is a fundamental agree- ment in the developmeut of the brain in men and apes. Gratiolet originated the statement that there is a fundamental difference in the development of the brains of apes and that of man — consisting in this; that, in the apes, the sulci which first make their appearance are situated on the posterior region of the cerebral hemi- spheres, while, in the liuman foatus, the sulci first become visible on the frontal lobes."* This general statement is based upon two observations, the one of a Gibbon almost ready to be born, in which the posterior gyri were " well " developed," while those of the frontal lobes were'* hardly indicated "''" (1. c. p. 39), and the other of a human foetus at the 22nd or 23rd week of uterogestation, in which Gratiolet notes that the insula was un- covered, but that nevertheless " des incisures sement le lobe anterieur, " une scissure pen profonde indique la separation du lobe occipital, tres- '' " Chez tous les singes, les plis Rolando, and one of the frontal " posterieurs se developpent les pre- sulci, plainly enough. Nevertheless, *' miers ; les plis anterieurs se M. Alix, in his ' Xotice sur les " developpent plus tard, aussi la travaux anthropologiques de Gratio- *' vert^bre occipitale et la parietale let ' (Mem. de la Societe d'Anthro- **sont-ellesrelativemeuttres-grandes pologie de Paris,' 1868, p. xxxii.), " chez le foetus. L'Horame presente writes thus : " Gratiolet a eu outre *' une exception remarquable quant " les mains le cerveau d'un fa>tus de " i I'epoque de Tapparitioa des plis " Gibbon, singe emiuemment su- " frontaux, qui sont les premiers " perieur, et tellement rapproche de *' indiquus ; niais le developpement " I'orang, que des naturalistes tres- *• general du lobe frontal, envisage " competeuts I'ont range parmi les " seulement par rapport a son " anthropoides. M. Huxley, par ex- *' volume, suit les memeslois que dans " emple, u'hesite pas sur ce point. " les singes :" Gratiolet, ' Memoire " Eh bien, c'est sur le cerveau d'un sur les plis cerebraux de I'Homme *' foetus de Gibbon que Gratiolet a et des Primates,' p. 39, tab. iv. " vu les circonvolutiuns du lobe tem- fig. 3. " poro-Sfjhenoidal deja deceloppecs '''' Gratiolet's words are (1. c. p. '■'■ lorsqu'il n existent pas encore de plis 39): "Dans le foetus don t 11 s'agit " s/^r le lobe frontal. II etait done " les plis cerebraux posterieurs sont " bien autorise a dire que, cliez " bien developpes, tandis que les " I'homme les circonvolutious aj)pa- " plis du lobe frontal sont i peine " raissent d'a eu w, tandis que chez " indiques." The figure, however " les singes elles se developpent (PI. iv. fig. 3), shews the fissure of " d'w en a." 204 The Descent of Man. Part I. " rediiit, d'ailleurs des cctte epoque. Le reste de la siuface cerebrale " eit encore absolument lisse." Three views of this brain are given in Plate 11. figs, 1, 2, 3, of the work cited, shewing the upper, lateral and inferior views of the hemi- spheres, but not the inner view. It is worthy of note that the figure by no means bears out Gratiolet's description, inasmuch as tlie fissure (anterotempoi al) on the posterior half of the face of the hemisphere, is more marked than any of those vaguely indicated in the anterior half. If the figure is correct it in no way justifies Gratiolet's conclusion : " II y a done entre ces cerveaux [those of a Callithrix and of a Gibbon] et " celui du foetus humain une ditierence fondamental. Chez celui-ci, long- " temps avant que les plis temporaux apparaissent, les plis frontaux " essayent d'exister." Since Gratiolet's time, however, the development of the gyri and sulci of the brain has been made the subject of renewed investigation by Schmidt, Bischoft', Pansch,"* and more particularly by Ecker,^^ whose work is not only the latest, but by far the most complete, memoir on the subject. The final resiilts of their inquiries may b© summed up as follows : — 1. In the human foetus, the sylvian fissure is formed in the course of the third month of uterogestation. In this, and in the fourth month, the cerebral hemispheres are smooth and rounded (with the exception of the sylvian depression), and they project backwards far beyond the cerebellum. 2. The sulci, properly so called, begin to appear in the interval between the end of the fourth and the beginning of the sixth month of foetal life, but Ecker is careful to point out that, not only the time, but the order, of their appearance is subject to considerable individual variation. In no case, however, are either the frontal or the temporal sulci the earliest. The fir;.t which appears, in fact, lies on the inner face of the hemi- sphere (whence doubtless Gratiolet, who does not seem to have examined that face in his foetus, overlooked it), and is either the internal perpen- dicular (occipito-parietal), or the calcarine sulcus, these two being close together and. eventually running into one another. As a rule the occipito-parietal is the earlier of the two. 3. At the latter part of this period, another sulcus, the " posterio, parietal," or " Fissure of Rolando "' is developed, and it is followed, in the course of the sixth month, by the other principal sulci of the fiontal, parietal, tempoial and occipital lobes. There is, however, no clear evidence that one of these constantly appears before the otlier; and it is remarkable that, in the brain at the period described and figured by Ecker (I. c. p. 212-13, Taf. II. figs. 1, 2, 3, 4), the antero- temporal sulcus {scissure parallele) so characteristic of the ape's brain, IS as well, if not better developed than the fissure of llolando, and is much more marked than the proper frontal sulci. Taking the facts as they now stand, it appears to me that the order of the appearance of the sulci and gyri in the foetal human brain is iu perfect harmony with the general tloctrine of evolution, and with the '* ' Ueber die typische Anordnung ^^ ' Zur Entwickelungs Geschichte der Furchen und Windungea auf der Furchen und Windungen der den Grosshirn-Hemispharen des Grosshirn-Hemispharen im Foetus Menschen und der Aften.' 'Archiv des MeHschen.' ' Archiv fiir Anthro- fiir Anthropologie,' iii., 1868. pologie,' iii., 1868. Chap. Y 1 1. StructtLve of tJie Brain. 205 view that man has been evolved from some ape- like form ; though there can be no doubt that that form was, in many respects, ditieient from any member of the Frimates now living. Von Buer taught us, half a century ago, that, in the course of their development, allied animals put on, at first, the characters of the greater groups to which they belong, and, by degrees, assume those which restrict them within the limits of their "family, genus, and species ; and he proved, at the same time, that no developmental stage of a higher ituimal is precisely similar to the adult condition of any lower animal, it is quite correct to say that a frog passes through the condition of a fish, inasmuch as at one period of its life the tadpole has all the cha- racters of a fish, and, if it went no further, would have to be grouped among fishes. But it is equally true that a tadpole is very different from any known fish. In like manner, the brain of a human foetus, at the fifth month, may correctly be said to be, not only the braiu of an ape, but that of a:i Arctopitheciue or marmoset-like ape ; for its hemispheres, with their great posterior lobster, and with no sulci but the sylvian and the calcarine, present the characteristics found only in the group of the Arctopilhecine Primates. But it is equally true, as Gratiolet remarks, that, in its widely open sylvian fissure, it differs from the biain of any actual marmoset. No doubt it would be much more similar to the brain of an advanced foetus of a marmoset. But we know nothing whatever of the development of the brain in the marmosets. In the Platyrhini proper, the only observation with which I am acquainted is due to Pansch, who found in the brain of a foetal Cehus Apella, in addition to the sylvian fissure and the deep calcarine fissure, only a very shallow anterotemporal fissure (sc/ssare parallele of Gratiolet.) Now this fact, taken together with the circumstance that the antnro- temporal sulcus is present in such Platyrhini as the Saimiri, which present mere traces of sulci on the anterior half of the exterior of the cerebral hemispheres, or none at all, undoubtedly, so far as it goes, affords fair evidence in favour of Graliolet's hypothesis, that the ])osterior sulci appear before the anterior, in the brains of the riatyrldui. But, it by no means follows, that the rule which may hold good for the PlatyrJuni extends to the Catarhini. We have no in- formation whatever respecting the development of the brain in the Cyiunnorpha; and, as regards the Anthropomorplta, nothing but the account of the brain of the Gibbon, near biitli, already referred to. At the present moment, there is not a shadow of evidence to shew that the sulci of a chiiupanzee's, or orang's, brain do not appear in the same order as a man's. Gratiolet opens his preface with the aphorism. " II est dangereux " dans les sciences de conclure trop vite." I fear he must have for- goiten this sound maxim by the time he had reached the discussion of the differences between men and apes, in the body of his work. No doubt, the excellent author of one of the most remarkable contributions to the just understanding of the mammalian brain which has ever been made, would have been the first to admit the insufficiency of his data had he lived to profit by the advance of inquiry. The misfortune is tliat his conclusions have been employed by persons incompetent to appreciate their foundation, as arguments in favour of obscurantism." *" For example, !M. I'Abbe Lecomte winisme et I'origine de THomme. ia his terrible pamphlet ' Le Dar- 1873. 2o6 T]ie Descent of Man. Part I. But it is important to remark that, whether Gratiolet was right or wrong in- his hypothesis respecting the relative order of appeaiance of the temporal and frontal sulci, the fact remains ; that, before either temj)oral or frontal sulci, appear, the foetal brain of man presents characters which are found only in the lowest group of the Primates (leaving out the Lemurs) ; and that this is exactly what we shouLl expect to be the case, if man has resulted from the gradual modifica- tion of the same form as that from which the other Primates have sprung. ( 207 ) Part LL SExXUAL SELECTION. CHAPTEE VIII. Principles of Sexual Selection. Secondary sexual characters — Sexual selection — Manner of action— Ex- cess of males — Polygamy — The male alone generally modified through sexual selection — Eagerness of the male — Variability of the male — Choice exerted by the female — Sexual compared with natural selection — Inheritance, at corresponding periods of life, at corresponding seasons of the year, and as limited by sex — Relations between the several forms of inheritance — Causes why one sex and the young are not modified through sexual selection — Supplement on the proportional numbers of the two sexes throughout the animal kingdom — The proportion of the sexes in i-elation to natural selection. "^'iTH animals which have their sexes separated, the males necessarily differ from the females in their organs of reproduction; and these are the primary sexual characters. But the sexes often differ in what Hunter has called secondary sexual charac- ters, which are not directly connected with the act of reproduc- tion ; for instance, the male possesses certain organs of sense or locomotion, of which the female is quite destitute, or has them more highly-developed, in order that he may readily find or reach her ; or again the male has special organs of prehension for holding her securely. These latter organs, of infinitely diversified kinds, graduate into those which are commonly ranked as primary, and in some cases can hardly be distinguished from them ; we see instances of this in the complex appendages at the apex of the abdomen in male insects. Unless indeed we confine the term "primary" to the reproductive glands, it is scarcely possible to decide which ought to be called primary and which secondary. The female often differs from tlie male in having organs for the nourishment or protection of her young, such as the mammary 2o8 The Descent of Man. Part II. glands of mammals, and tlie abdominal sacks of the marsupials. In some few cases also the male possesses similar organs, which are wanting in the female, snch as the receptacles for the ova in certain male fishes, and those temporarily deyeloped in certain male frogs. The females of most bees are provided with a special apparatus for collecting and carrying pollen, and their ovipositor is modified into a sting for the defence of the larvae and the community. Many similar cases could be given, but they do not here concern us. There are, however, other sexual differences quite unconnected with the primary reproductive organs, and it with is these that we are more especially concerned — such as the greater size, strength, and pugnacity of the male, his weapons of offence or means of defence against rivals, his gaudy colouring and various ornaments, his power of song, and other such characters. Besides the primary and secondary sexual differences, such as the foregoing, the males and females of some animals differ in structures related to different habits of life, and not at all, or only indirectly, to the reproductive functions. Thus the females of certain flies (Cuhcidse and Tabanidse) are blood-suckers, whilst the males, living on flowers, have mouths destitute of mandibles.^ The males of certain moths and of some crustaceans (e. (J. Tanais) have imperfect, closed mouths, and cannot feed. The complemeutal males of certain Cirripedes live like epiphytic plants either on the female or the hermaphrodite form, and are destitute of a mouth and of prehensile limbs. In these cases it is the male which has been modified, and has lost certain important organs, which the females possess. In other cases it is the female which has lost such parts; for instance, the female glow- worm is destitute of wings, as also are many female moths, some of which never leave theii- cocoons. Many female parasitic crustaceans have lost their natatory legs. In some weevil-beetles (Curcu- lionidse) there is a great difference between the male and female in the length of the rostrum or snout ; ^ but the meaning of this and of many analogous differences, is not at all understood. Differences of structure between the two sexes in relation to different habits of life are generally confined to the lower animals ; but with some few birds the beak of the male differs from that of the female. In the Huia of New Zealand the difference is wonderfully great, and we hear from Dr. Duller ^ ^ Westwood, 'Modern Class, of - Kirby and Spence, ' Introduc- Insects,' vol. ii. 1840, p. 541. For tion to Entomology,' vol. iii. 1826, the statement about Tanais, men- p. 309. tioned below, I am indebted to Fritz ^ ' Bii^jg ^f New Zealand,' 1872, Miiller. p. 66. Chap. VIII. Sexual Selection. 209 that the male uses his strong beak in chiselling the larvre of insects out of decayed wood, whilst the female probes the softer parts with her far longer, much curved and pliant beak : and thus they mutually aid each other. In most cases, differences of structure between the sexes are more or less directly connected with the propagation of the species : thus a female, which has to nourish a multitude of ova, requires more food than the male, and consequently requires special means for procuring it. A male animal, which lives for a very short time, might lose its organs for procuring food through disuse, without detriment ; but he would retain his locomotive organs in a perfect state, so that he might reach the female. The female, on the other hand, might safely lose her organs for flying, swimming, or walking, if she gradually acquired habits which rendered such powers useless. We are, however, here concerned only with sexual selection. This depends on the advantage which certain individuals have over others of the same sex and species solely in respect of reproduction. When, as in the cases above mentioned, the two sexes differ in structure in relation to different habits of life, they have no doubt been modified through natural selection, and by inheritance limited to one and the same sex. So again the primary sexual organs, and those for nourishing or protecting the young, come under the same influence ; for those individuals which generated or nourished their offspring best, would leave, cctteris paribus, the greatest number to inherit their superiority ; whilst those which generated or nourished their offspring badly, would leave but few to inherit their weaker powers. As the male has to find the female, he requires organs of sense and locomotion, but if these organs are necessary for the other purposes of life, as is generally the case, they will have been developed through natural selection. When the male has found the female, he sometimes absolutely requires prehensile organs to hold her; thus Dr. Wallace informs me that the males of certain moths cannot unite with the females if their tarsi or feet are broken. The males of many oceanic crustaceans, when adult, have their legs and antennae modified in an extraordinary manner for the . prehension of the female ; hence we may suspect that it is be- cause these animals are washed about by the waves of the open sea, that they require these organs in order to propagate their kind, and if so, their development has been the result of ordinary or natural selection. Some animals extremely low in the scale have been modified for this same purpose ; thus the males of certain parasitic worms, when fully grown, have the lower surface of the terminal part of their bodies roughened 2 lo The Descent of Alan. Pakt II, like a rasp, and with this they coil round and permanently hold the females.* • When the two sexes follow exactly the same habits of life, and the male has the sensory or locomotive organs more highly developed than those of the female, it may be that the perfection of these is indispensable to the male for finding the female ; but in the vast majority of cases, they serve only to give one male an advantage over another, for with sufficient time, the less well- endowed males would succeed in pairing with the females ; and judging from the structure of the female, they would be in all other respects equally well adapted for their ordinary habits of life. Since in such cases the males have acquired their present structure, not from being better fitted to survive in the struggle for existence, but from having gained an advantage over other males, and from having transmitted this advantage to their male offspring alone, sexual selection must here have come into action. It was the importance of this distinction which led me to designate this form of selection as Sexual Selection. So again, if the chief service rendered to the male by his prehensile organs is to prevent the escape of the female before the arrival of other males, or when assaulted by them, these organs '^ill have been perfected through sexual selection, that is by the advantage acquired by certain individuals over their rivals. But in most cases of this kind it is impossible to distinguish between the effects of natural and sexual selection. Whole chapters could be filled with details on the differences between the sexes in their sensory, locomotive, and prehensile organs. As, however, these structures are not more interesting than others adapted for the ordinary purposes of life I shall pass them over almost entirely, giving only a few instances under each class. There are many other structures and instincts which must have been developed through sexual selection— such as the weapons of offence and the means of defence of the males for fighting with and driving away their rivals— their courage and pugnacity — their various ornaments — their contrivances for pro- * M. Perrier advances this case claspers of certain male animals ('Revue Scientifique,' Feb. 1, 1873, could not have been developed p. 865) as one fatal to the belief in through the choice of the female I sexual selection, inasmuch as he Had J not met with this remark, I supposes that I attribute all the should not have thought it possible differences between the sexes to for any one to have read this chapter sexual selection. This distinguished and to have imagined that I main- naturalist, therefore, like so many tain that the choice of the female other Frenchmen, has not taken the had anything to do with the develop- trouble to understand even the first meut of the prehensile organs in the principles of sexual selection. An male. English naturalist insists that the Chap. VII r. Sexual Selection. 211 duciiig vocal or instrumental music — and their glands for emitting odours, most of these latter structures serving only to allure or excite the female. It is clear that these characters are the result of sexual and not of ordinary selection, since unarmed, unornamented, or unattractive males would succeed equally well in the battle for life and in leaving a numerous jDrogeny, but for the presence of better endowed males. We may infer that this would be the case, because the females, which arc unarmed and unornamented, are able to survive and procreate their kind. Secondary sexual characters of the kind just referred to, will be fully discussed in the following chapters, as being in many respects interesting, but especially as depending on the will, choice, and rivalry of the individuals ot either sex. When we behold two males fighting for the possession of the female, or several male birds displaying their gorgeous plumage, and per- forming strange antics before an assembled body of females, we cannot doubt that, though led by instinct, they know what they are about, and consciously exert then' mental and bodily powers. Just as man can improve the breed of his game-cocks by the selection of those birds which are victorious in the cockpit, so it appears that the strongest and most vigorous males, or those provided with the best weapons, have prevailed under nature, and have led to the improvement of the natural breed or species. A slight degree of variability leading to some advantage, how- ever slight, in reiterated deadly contests would suffice for the work of sexual selection; and it is certain that secondary sexual characters are eminently variable. Just as man can give beauty, according to his standard of taste, to his male poultry, or more strictly can modify the beauty originally acquired by the parent species, can give to the Sebright bantam a new and elegant plumage, an erect and peculiar carriage— so it appears that female bii'ds in a state of nature, have by a long selection of the more attractive males, added to their beauty or other attractive quahties. No doubt this implies powers of discrimination and taste on the part of the female wliich will at first appear extremely improbable; but by the facts to be adduced here- after, I hope to be able to shew that the females actually have these powers. When, however, it is said that the lower animals have a sense of beauty, it must not be supposed that such sense is comparable with that of a cultivated man, with his multiform and complex associated ideas. A more just com- parison would be between the taste for the beautiful in animals, and that in the lowest savages, who admire and deck themselves with any brilliant, glittering, or curious object. From our ignorance on several points, the precise manner in 212 The Descent of Man. Part IL which sexual selection acts is somewhat "uncertain. Neverthe- less if those naturalists who already believe in the mutability of species, will read the following chapters, they will, I think, agree with me, that sexual selection has played an important part in the history of the organic world. It is certain that amongst almost all animals there is a struggle between the males for the possession of the female. This fact is so notorious that it would be superfluous to give instances, Hence the females have the opportunity of selecting one out of several males, on the suppo- sition that their mental capacity suffices for the exertion of a choice. In many cases special circumstances tend to make the struggle between the males particularly severe. Thus the males of our migratory birds generally arrive at their places of breeding before the females, so that many males are ready to contend for each female. I am informed by Mr. Jenner Weir, that the bird- catchers assert that this is invariably the case with the nightin- gale and blackcap, and with respect to the latter he can himself confirm the statement. Mr. Swaysland of Brighton has been in the habit, during the last forty years, of catching our migratory birds on their first arrival, and he has never known the females of any species to arrive before their males. During one spring he shot thirty -nine males of Eay's wagtail {Budytes Rail) before he saw a single female. Mr. Gould has ascertained by the dissection of those snipes which arrive the first in this country, that the males come before the females. And the like holds good with most of the migratory birds of the United States.^ The majority of the male salmon in our rivers, on coming up from the sea, are ready to breed before the females. So it appears to be with frogs and toads. Throughout the great class of insects the males almost always are the first to emerge from the pupal state, so that they generally abound for a time before any females can be seen.*^ The cause of tliis difference between the males and females in their periods of arrival and maturity is sufficiently obvious. Those males which annually first migrated into any country, or T\^hich in the spring were first ready to breed, or were the most eager, would leave the largest number of ofl"spring ; and these ' J. A. Allen, on the 'Mammals rodite plants are dichogamous ; that and Winter Birds of Florida,' Bull. is, their male and female organs are Comp. Zoology, Harvard College, p. not ready at the same time, so that 268. they cannot be self-fertilised. Now ^ Even with those plants in which in such flowers, the pollen is in the sexes are separate, the male general matured before the stigma, flowers are generally mature be- though there are exceptional cases fore the fernale. As first shewn in Avhich the female organs are by C. K. Sprengel, many hermaph- beforehaad. Chap. VIII. Sexual Selection. 213 would tend to inherit similar instincts and constitutions. It must be borne in mind that it would have been impossible to change very materially the time of sexual maturity in the females, without at the same time interfering with the period of the production of the young— a period which must bo determined by the seasons of the year. On the whole there can be no doubt that with almost all animals, in which the sexes are separate, there is a constantly recurrent struggle between the males for the possession of the females. Our difficulty in regard to sexual selection lies in understand- ing how it is that the males which conquer other males, or those which prove the most attractive to the females, leave a greater number of offspring to inherit their superiority than their beaten and less attractive rivals. Unless this result does follow, the charactei-s which give to certain males an advantage over others, could not be perfected and augmented through sexual selection. When the sexes exist in exactly equal numbers, the vrorst-endowed males will (except where polygamy prevails), ultimately find females, and leave as many offspring, as well fitted for theu' general habits of life, as the best-endowed males. From various facts and considerations, I formerly inferred that with most animals, in which secondary sexual characters are well developed, the males considerably exceeded the females in number; but this is not by any means always true. If the males were to the females as two to one, or as three to two, or even in a somewhat lower ratio, the whole affair would be simple; for the better-armed or more attractive males would leave the largest number of offspring. But after investigating, as far as possible, the numerical proportion of the sexes, I do not beheve that any great inequality in number commonly exists. In most cases sexual selection appears to have been effective in the following manner. Let us take any species, a bird for instance, and divide the females inhabiting a district into two equal bodies, the one consisting of the more vigorous and better-nourished individuals, and the other of the less vigorous and healthy. The former, there can be little doubt, would be ready to breed in the spring before the others ; and this is the opinion of ]\Ir. Jenncr Weir, who hasT^arefully attended to the habits of birds during many years. There can also be no doubt that the most vigorous, best-nourished and earhest breeders would on an average succeed in rearing the largest number of fine offspring.'^ The males, as we have seen, are generally ready to breed before the * Here is excellent evidence on an experienced ornithologist. Mr. the character of the ofispring from J. A. Allen, in speaking ('Mammals 214 The Descent of Man. Part I L females ; the strongest, and with some species the best armed of the males, drive away the weaker ; and the former would then unite with the more vigorous and better-nourished females, be- cause they are the first to breed.^ Such vigorous pairs would surely rear a larger number of offspring than the retarded females, which would be compelled to unite with the conquered and less powerful males, supposing the sexes to be numerically equal ; and this is all that is wanted to add, in the course of successive generations, to the size, strength and courage of the males, or to improve their weajDons. But in very many cases the males which conquer their rivals, do not obtain possession of the females, independently of the choice of the latter. The courtship of animals is by no means so simple and short an affair as might be thought. The females are most excited by, or prefer pairing with, the more ornamented males, or those which are the best songsters, or play the best antics; but it is obviously probable that they would at the same time prefer the more vigorous and lively males, and this has in. some cases been confirmed by actual observation.^ Thus the more vigorous females, which are the first to breed, will have the choice of many males ; and though they may not always select the strongest or best armed, they will select those which are vigorous and well armed, and in other respects the most at- tractive. Both sexes, therefore, of such early pairs would as above explained, have an advantage over others in rearing offspring ; and this apparently has suflficed during a long course of generations to add not only to the strength and fighting powers of the males, but Hkewise to their various ornaments or other attractions. In the converse and much rarer case of the males selecting particular females, it is plain that those which were the most vigorous and had conquered others, would have the freest choice ; and it is almost certain that they would select vigorous as well as attractive females. Such pairs would have an advan- and Winter Birds of E. Florida,' to those female bees which are the p. 229) of the later broods, after the first to emerge from the puj^a each accidental destruction of the first, year. See his remarkable essaj-, bays, that these " are found to be 'Anwendung den Darwin'schen Lehra " smaller and paler-coloured than auf Bienen,' ' Verh. d. ^ . Jahrg.' " those hatched earlier in the sea- xxix. p. 45. *' son. In cases where several broods ^ With respect to poultry, I have " are reared each year, as a general received information, hereafter to " rule the birds of the earlier broods be given, to this effect. Even with " seem iji all respects the most per- birds, such as pigeons, which pair *' feet and vigorous." for life, the female, as I hear from ^ Hermann Miiller has come to Mr. Jenner Weir, will desert her this same conclusion with respect mate if he is injured or grows weak. Uh.\ 1'. VIII. Scxnal Selection. 2 1 5 tage in rearing offspring, more especially if the male had the power to defend the female during the pairing-season as occurs with some of the higher animals, or aided her in providing for the young. The same principles would apply if each sex pre- ferred and selected certain individuals of the opposite sex ; supposing that they selected not only the more attractive, but likewise the more vigorous individuals. Numerical Proportion of the Two Sexes. — I have remarked that sexual selection would be a simple affair if the males were con- siderably more numerous than the females. Hence I was led to investigate, as far as I could, the proportions between the two sexes of as many animals as possible; but the materials are scanty. I will here give only a brief abstract of the results, retaining the details for a sujiplementary discussion, so as not to interfere with the course of my argument. Domesticated animals alone afford the means of ascertaining the propor- tional numbers at birth; but no records have been specially kept for this purpose. By indirect means, however, I have collected a considerable body of statistics, from which it appears that with most of our domestic animals the sexes are nearly equal at birth. Thus 25,560 births of race-horses have been recorded during twenty-one years, and the male births were to the female births as 99"7 to 100. In greyhounds the in- equality is greater than with any other animal, for out of 6878 births dui-ing twelve* years, the male births were to the female as 110-1 to 100. It is, however, in some degree doubtful whether it is safe to infer that the proportion would be the same under natural conditions as under domestication ; for slight and unknown differences in the conditions affect the proi^ortion of the sexes. Thus with mankind, the male births in England are as 101'5, in Russia as 108'9, and with the Jews of Livonia as 120, to 100 female births. But I shall recur to this curious point of the excess of male births in the supplement to this chapter. At the Cape of Good Hope, however, male children of Euroj^ean extraction have been born during several years in the proportion of between 90 and 99 to 100 female children. For our present purpose we are concerned with the proportion of the sexes, not only at birth, but also at maturity, and this adds another element of doubt ; for it is a well-ascertained fact that with man the number of males dying before or during birth, and during the first few years of infancy, is considerably larger than that of females. So it almost certainly is with male lambs, and probably with some other animals. The males of some species kill one another by fighting ; or they drive one another about 2 1 6 The Descent of Man. Tart II. until they become greatly emaciated. Tliey must also be often exposed to yarious dangers, whilst wandering about in eager search for the females. In many kinds of fish the males are- much smaller than the females, and they are beheved often to be devoured by the latter, or by other fishes. The females of some birds appear to die earlier than the males; they are also liable to be destroyed on their nests, or whilst in cliarge of their young. With insects the female laryse are often larger than those of the males, and w^ould consequently be more likely to be. devoured. In some cases the mature females are less active and less rapid in their movements than the males, and could not escape so well from danger. Hence, with animals in a state of nature, wo must rely on mere estimation, in order to judge of the proportions of the sexes at maturity ; and this is but little trustworthy, except when the inequality is strongly marked. Nevertheless, as far as a judgment can be formed, we may conclude from the facts given in the supplement, that the males of some few mammals, of many birds, of some fish and insects, are considerably more numerous than the females. The proportion between the sexes fluctuates slightly during successive years : thus with race-horses, for every 100 mares born the stallions varied from 107'1 in one year to 92-6 in another year, and with greyhounds from 116"3 to 95*3. But had larger num- bers been tabulated throughout an area more extensive than England, these fluctuations would probably have disappeared ; and such as they are, would hardly suffice to lead to efi'ective sexual selection in a state of nature. Nevertheless, in the cases of some few wild animals, as shewn in the supi3lement, the proportions seem to fluctuate either during different seasons or in different localities in a sufficient degree to lead to such selection. For it should be observed that any advantage, gained during certain years or in certain localities by those males which were able to conquer their rivals, or were the most attractive to the females, would probably be transmitted to the offspring, and would not subsequently be eliminated. During the succeeding seasons, when, from the equality of the sexes, every male was able to procure a female, the stronger or more at- tractive males previously produced would si ill have at least as good a chance of leaving offspring as the weaker or less attractive. Polygamy. — The practice of polygamy leads to the same results as would follow from an actual inequality in the number of the sexes ; for if each male secures two or more females, many males cannot pair ; and the latter assuredly will be the weaker or less attractive individuals. Many mammals and some few birds are Chap. VI II. Sexual Selection. 217 polygamous, but with animals belonging to the lower classes I have found no evidence of this habit. The intellectual powers of such animals are, perhaps, not sufificicnt to lead them to collect and guard a harem "of females. That some relation exists between polygamy and the development of secondary sexual characters, appears nearly certain ; and this supports the view that a numerical preponderance of males would be eminently favourable to the action of sexual selection. Nevertheless many animals, which are strictly monogamous, especially birds, display strongly-marked secondary sexual characters ; whilst some few animals, which are polygamous, do not have such characters. \Ye will jfirst briefly run through the mammals, and then turn to birds. The gorilla seems to be polygamous, and the male differs considerably from the female ; so it is with some baboons, which live in herds containing twice as many adult females as males. In South America the Mycetts caraya presents well- marked sexual differences, in colour, beard, and vocal organs ; and the male generally lives with two or three wives : the male of the Cehus capucinus differs somewhat from the female, and appears to be polygamous.^*^ Little is known on this head with respect to most other monkeys, but some species are strictly monogamous. The ruminants are eminently polygamous, and they present sexual differences more frequently than almost any other group of mammals; this holds good, especially in their weapons, but also in other characters. Most deer, cattle, and sheep are polygamous ; as are most antelopes, though some are monogamous. Sir Andrew Smith, in speaking of the antelopes of South Africa, says that in herds of about a dozen there was rarely more than one mature male. The Asiatic Amilope saiga appears to be the most inordinate polygamist in the world ; for Pallas ^^ states that the male drives away all rivals, and collects a herd of about a hundred females and kids together ; the female is hornless and has softer hair, but does not otherwise differ much from the male. The wild horse of the Falkland Islands and of the Western States of N. America is polygamous, but, except in his greater size and in the proportions of his body, differs but little from the mare. The wild boar presents well-marked sexual " On the Gorilla, Savage and Fasc. xii. 1777, p. 29, Sir Andrew Wyman. ' Boston Journal of Nat. Smith, ' Illustrations of the Zoology Hist.* vol. V. 1845-47, p. 423. On of S. Africa,' 1849, pi. 29, on the Cynocephalus, Brehm, 'lUust.Thier- Kobus. Owen, in his ' Anatomy of leben,' B. i. 1864, s. 77. On My- Vertebrates' (vol. iii. 1868, p. 6":33) cetes, Rengger, 'Xaturgesch.: Siiuge- gives a table shewing incidentally thiere von Paraguay,' 1830, s. 14, which species of antelopes are gre- 20. Cebus, Brehm, 'ibid. s. 108, garious. " Pallas, 'S])icilegia Zoolog.,' 2 1 8 The Descent of Man. Pakt II. characters, in his gi'eat tusks and some other points. In Europe and in India he leads a solitary hfe, except during the breeding- season ; but as is beUeved by Sir W. Elliot, who has had many opportunities in India of observing this animal, he consorts at this season "with several females. "Whether this holds good in Europe is doubtful, but it is supported by some evidence. The adult male Indian elephant, like the boar, passes much of Ms time in solitude ; but as Dr. Campbell states, when with others, " it is rare to find more than one male with a whole herd " of females ;" the larger males expelling or killing the smaller and weaker ones. The male differs from the female in his immense tusks, greater size, strength, and endurance; so great is the difference in these respects, that the males when caught are valued at one-fifth more than the females.^^ The sexes of other pachydermatous animals differ very little or not at all, and, as far as known, they are not polygamists. Nor have I heard of any species in the Orders of Cheiroptera, Edentata, Insectivora and Piodents being polygamous, excepting that amongst the Eodents, the common rat, according to some rat-catchers, lives with several females. Nevertheless the two sexes of some sloths (Edentata) differ in the character and colour of certain patches of hair on their shoulders.^^ And many kinds of bats (Chehoptera) present well-marked sexual differences, chiefly in the males possessing odoriferous glands and pouches, and by their being of a lighter colour.^^ In the great order of Eodents, as far as I can learn, the sexes rarely differ, and when they do so, it is but shghtly in the tint of the fur. As I hear from Sir Andrew Smith, the lion in South Africa sometimes lives with a single female, but generally with more, and, in one case, was found with as many as five females ; so that he is polygamous. As far as I can discover, he is the only polygamist amongst all the terrestrial Carnivora, and he alone presents well-marked sexual characters. If, however, we turn to the marine Carnivora, as we shall hereafter see, the case is widely different ; for many species of seals offer extraordinary sexual differences, and they are eminently polygamous. Thus, according to Peron, the male sea-elephant of the Southern Ocean always possesses sever-ai females, and the sea-lion of Forster is said to be surrounded by from twenty to thirty females. In the North, the male sea-bear of Steller is accompanied by even a ^2 Dr. Campbell, in ' Proc. Zoo- ' '^ Dr. Gray, in * Annals and log. Soc' 1869, p. 138. See also an Mag. of Nat. Hist.' 1871, p. 302. interesting paper, by Lieut. John- ^'^ See Dr. Dobson's excellent stone, in ' Proc. Asiatic Soc. of paper, in ' Proc. Zoolog. Soc' 1873, Bengal,' May, 1868. p. ii41. CiiAP. VIII. Sexual Selection. 219 greater number of females. It is an interesting fact, as Dr. Gill remarks,^^ that in the monogamous species, " or those " living in small communities, there is little difference in size " between the males and females ; in tlie social species, or rather " those of which the males have harems, the males are vastly " larger than the females." Amongst birds, many species, the sexes of which differ greatly from each other, are certainly monogamous. In Great Britain we see well-marked sexual differences, for instance, in the wild- duck which pairs with a single female, the common blackbird, and the bullfinch which is said to pair for life. I am informed by Mr. Wallace that the like is true of the Chatterers or Cotingidcie of South America, and of many other birds. In several groups I have not been able to discover whether the species are polygamous or monogamous. Lesson says that birds of paradise, so remarkable for their sexual differences, are polygamous, but Mr. Wallace doubts wdiether he had sufficient evidence. IMr. Salviu tells me he has been led to believe that humming-bii'ds are polygamous. The male widow-bird, remarkable for his caudal plumes, certainly seems to be a polygamist.^^ I have been assured by Mr. Jenner Weir and by others,. that it is somewhat common for three starlings to frequent the same nest ; but whether this is a case of polygamy or polyandry has not been ascertained. The Gaihnacese exhibit almost as strongly marked sexual differences as birds of paradise or humming-birds, and many of the species are, as is well known, polygamous ; others being strictly monogamous. What a contrast is presented between the sexes of the polygamous peacock or pheasant, and the mono- gamous guinea-fowl or partridge ! Many similar cases could be given, as in the grouse tribe, in which the males of the poly- gamous capercailzie and black-cock differ greatly from the females; whilst the sexes of the monogamous red grouse and ptarmigan differ very little. In the Cursores, except amongst the bustards, few species offer strongly-marked sexual dif- ferences, and the great bustard {0th tarda) is said to be poly- gamous. With the Grallatores, extrem.ely few species differ sexually, but the ruff {Machetes jniunax) affords a marked " The Eared Seals, ' American Great Bustard, see L. Lloyd, ' Game Naturalist,' vol. iv., Jan. 1871. Birds of Sweden,' 18G7, p. 19, and '^ 'The Ibis,' vol. iii. 1861, p. 182. Montagu and Selby speak of 133, on the Progne Widow-bird. the Black Grouse as polygamous See also on the Vidua axillaris^ and of the Red Grouse as mono- ibid. vol. ii. 1860, p. 211. On the gamous. polygamy of the Capercailzie and 220 The Descejit of Man. Part II. exception, and this species is belieyed by Montagu to be a polygamist. Hence it appears that amongst bii'ds there often exists a close relation between polygamy and the development of strongly-marked sexual differences. I asked Mr. Bartlett, of the Zoological Gardens, who has had yery large experience with birds, whether the male tragopan (one of the Gallinacese) was polygamous, and I was struck by his answering, " I do not " know, but should think so from his splendid colours." It deserves notice that the instinct of pairing with a single female is easily lost under domestication. The wild-duck is strictly monogamous, the domestic-duck highly polygamous. The Eev. W. D. Fox informs me that out of some half-tamed wild-ducks, on a large pond in his neighbourhood, so many mallards were shot by the gamekeeper that only one was left for every seven or eight females ; yet unusually large broods were reared. The guinea-fowl is strictly monogamous ; but Mr. Fox finds that his birds succeed best when he keeps one cock to two or three hens. Canary-birds pair in a state of nature, but the breeders in England successfully put one male to four or five females. I have noticed these cases, as rendering it probable that wild monogamous species might readily become either temporarily or permanently polygamous. Too little is known of the habits of reptiles and fishes to enable us to speak of their marriage arrangements. The stickle -back (Gasterosteus), however, is said to be a polygamist ;" and the male during the breeding season differs conspicuously from the female. To sum up on the means through which, as far as we can judge, sexual selection has led to the development of secondary sexual characters. It has been shewn that the largest number of vigorous offspring will be reared from the pairing of the strongest and best-armed males, victorious in contests over other males, with the most vigorous and best-nourished females, which are the first to breed in the spring. If such females select the more attractive, and at the same time vigorous males, they will roar a larger number of offspring than the retarded females, which must pair with the less vigorous and less attractive males. So it will be if the more vigorous males select the more attractive and at the same time healthy and vigorous females ; and this will especially hold good if the male defends the female, and aids in providing food for the young. The ad- vantage thus gained by the more vigorous pairs in rearing a larger number of offspring has apparently sufficed to render sexual selection efficient. But a large numerical preponderance 1^ Noel Humphreys, ' River Gardens/ 1857. Chap. VIII. Sexual Selection. 221 of males over females will bo still more efiBcient; whether the preponderance is only occasional and local, or permanent; whether it occurs at birth, or afterwards from the greater de- struction of the females ; or whether it indirectly follows from the practice of polygamy. The Male generally more raodified than the Female. — Throughout the animal kingdom, when the sexes differ in external appearance, it is, with rare exceptions, the male which has been the more moditied ; for, generally, the female retains a closer resemblance to the young of her own species, and to other adult members of the same group. The cause of this seems to lie in the males of almost all animals having stronger passions than the females. Hence it is the males that tight together and sedulously display their charms before the females ; and the victors transmit their superiority to their male offspring. Why both sexes do not thus acquire the characters of their fathers, will be considered here- after. That the males of all mammals eagerly pursue the females is notorious to every one. So it is with birds ; but many cock birds do not so much pursue the hen, as display their plumage, perform strange antics, and pour forth their song in her presence. The male in the few fish observed seems much more eager than the female; and the same is true of aUigators, and apparently of Batrachians. Throughout the enormous class of insects, as Kirby remarks, ^^ " the law is, that the male shall seek " the female." Two good authorities, Mr. Blackwall and Mr. C. Spence Bate, tell me that the males of spiders and crustaceans are more active and more erratic in their habits than the females. When the organs of sense or locomotion are present in the one sex of insects and crustaceans and absent in the other, or when, as is frequently the case, they are more highly developed in the one than in the other, it is, as far as I can discover, almost invariably the male which retains such organs, or has them most developed; and this shews that the male is the more active member in the courtship of the sexes.^^ '^ Kirby and Spence, * Introduc- females of this species are impreg- tion to Entomology,' vol. iii. 1826, nated by the males which are born p. 342. in the same cells with them ; but ^^ One parasitic Hymenopterous it is much more probable that the insect (Westwood, ' Modern Class, of females visit other cells, so that Insects,' vol. ii. p. 160) forms an close interbreeding is thus avoided, exception to the rule, as the male We shall hereafter meet in various has rudimentary wings, and never classes, with a few exceptional cases, quits the cell in which it is born, in which the female, instead of the whilst the female has well-develcped male, is the seeker and wooer, wings. Audouin believes that the 222 The Descent of Man. Part XL The female, on the other hand, with the rarest exceptions, is less eager than the male. As the illustrious Hunter ^^ long ago observed, she generally " requires to be courted ;" she is coy, and may often be seen endeavouring for a long time to escape from the male. Every observer of the habits of animals will be able to call to mind instances of this kind. It is shown by various facts, given hereafter, and by the results fairly attributable to sexual selection, that the female, though comparatively passive, generally exerts some choice and accepts one male in preference to others. Or she may accept, as appearances would sometimes lead us to beheve, not the male which is the most attractive to her, but the one which is the least distasteful. The exertion of some choice on the part of the female seems a law almost as general as the eagerness of the male. We are naturally led to enquire why the male, in so many and such distinct classes, has become more eager than the female, so that he searches for her, and plays the more active part in court- ship. It would be no advantage and some loss of power if each sex searched for the other; but why should the male almost always be the seeker? The ovules of plants after fertili- sation have to be noiuished for a time; hence the pollen is necessarily brought to the female organs — being placed on the stigma, by means of insects or the wind, or by the spontaneous movements of the stamens ; and in the Algas, &c., by the loco- motive power of the antherozooids. With lowly-organised aquatic animals, permanently affixed to the same spot and having their sexes separate, the male element is invariably brought to the female ; and of this we can see the reason, for even if the ova were detached before fertilisation, and did not require subsequent nourishment or protection, there would yet be greater difficulty in transporting them than the male element, because, being larger than the latter, they are produced in far smaller numbers. So that many of the lower animals are, in this re- spect, analogous with plants.^^ The males of affixed and aquatic animals having been led to emit their fertilising element in this way, it is natui'al that any of their descendants, which rose in the scale and became locomotive, should retain the same habit ; and they would approach the female as closely as jdos- sible, in order not to risk the loss of the fertilising element in a long passage of it thi'ough the water. With some few of the lower '" 'Essays and Observations.' of the male and female reproductive edited .by Owen, vol. i. 1861, p. cells, remarks, " verhalt sich die 194. " eine bei der Vereinigung activ, 2^ Prof. Sachs (' Lehrbuch der "... die andere erscheint bei der Botanik,' 1870, s. 633) in speaking " Vereinigung passiv." Chap. VIII. Seximl Selection. 223 animals, the females alone are fixed, and the males of these must be the seekers. But it is difficult to understand why the males of species, of which the progenitors wxre primordially free, should invariably have acquired the habit of approaching the females, instead of being approached by them. But in all cases, in order that the males should seek efiSciently, it would be necessary that they should be endowed with strong passions ; and the acquire- ment of such passions would naturally follow from the more eager leaving a larger number of offspring than the less eager. ' The great eagerness of the males has thus indirectly led to their much more frequently developing secondary sexual characters than the females. But the development of such characters would be much aided, if the males were more liable to vary than the females — as I concluded they were — after a long study of domesticated animals. Yon Nathusius, who has had very wide experience, is strongly of the same opinion.^^ Good evidence also in favour of this conclusion can be produced by a comparison of the two sexes in mankind. During the Novara Expedition ^^ a vast number of measurements was made of various parts of the body in different races, and the men were found in almost every case to present a greater range of variation than the women ; but I shall have to recur to this subject in a future chapter. Mr. J. Wood,^* who has carefully attended to the variation of the muscles in man, puts in italics the conclusion that " the greatest number of '' abnormalities in each subject is found in the males," He had previously remarked that "altogether in 102 subjects, the varieties " of redundancy were found to be half as many again as in " females, contrasting widely with the greater frequency of " deficiency in females before described." Professor Macalister likewise remarks ^^ that variations in the m.uscles " are probably " more common in males than females." Certain muscles which are not normally present in mankind are also more frequently developed in the male than in the female sex, although excei^tions to this rule are said to occur. Dr. Burt Wilder ^"^ has tabulated the cases of 152 individuals with supernumerary digits, of which 86 were males, and 39, or less than half, females, the remaining 27 being of unknown sex. It should not, however, be overlooked 22 * Vortrage liber Viehzucht,' my ' Variation of Animals and 1872, p. 63. Plants under Domestication,' vol, ii. -^ ' Reise der Kovara : Anthro- 1868, p. 75. polog. Theil,' 1867, s. 216-269. ^4 'Proceedings Royal Soc' vol. The results were calculated by Dr. xvi. July 1868, pp. 519 and 524. Weisbach from measurements made -^ ' Troc. Royal h-ish Academy,' by Drs. K. Scherzer and Schwarz. vol. x. 1868, p. 123. On the greater variability of the 2" 'Massachusetts Mehoeniceus the males have had their colours gi-eatly intensified in the south; w^hereas with Cur- diualis Virginia nus it is the females which have been thus affected ; with Quiscahis major the females have been rendered extremely variable in tint, whilst the reales remain nearly uniform.^^ A few exceptional cases occur in various classes of animals, in which the females instead of the males have acquired well pronounced secondary sexual characters, such as brighter colours, greater size, strength, or pugnacity. With birds there has some- times been a complete transposition of the ordinary characters proper to each sex ; the females having become the more eager in courtship, the males remaining comparatively passive, but apparently selecting the more attractive females, as we may infer from the results. Certain hen birds have thus been rendered more highly coloured or otherwise ornamented, as well as more powerful and jDugnacious than the cocks ; these characters being transmitted to the female offspring alone. It may be suggested that in some cases a double process of selection has been carried on; that the males have selected the more attractive females, and the latter the more attractive males. This process, however, though it might lead to the modification of both sexes, would not make the one sex different from the other, unless indeed their tastes for the beauti- ful differed ; but this is a supposition too improbable to be worth considering in the case of any animal, excepting man. There are, however, many animals in which the sexQs resemble each other, both being furnished with the same ornaments, which analogy would lead us to attribute to the agency of sexual selection. In such cases it may be suggested with more plausi- bility, that there has teen a double or mutual process of sexual solection ; the more vigorous and precocious females selecting the more attractive and vigorous males, the latter rejecting all except tho more attractive females. But from what we know *' ' Mamtuals and Birds of E. Florida,' pp. 234, 280, 295. 11 226 The Descent of Man. Paet II. of the habits of animals, this view is hardly probable, for the male is generally eager to pair Tvith any female. It is more probable that the ornaments common to both sexes were acquired by one sex, generally the male, and then transmitted to the off- spring of both sexes. If, indeed, during a lengthened period the males of any species were gi'eatly to exceed the females in number, and then during another lengthened period, but under different conditions, the reverse were to occur, a double, but not simultaneous, process of sexual selection might easily be carried on, by which the two sexes might be rendered widely different. We shall hereafter see that many animals exist, of which neither sex is brilliantly coloured or provided with special orna- ments, and yet the members of both sexes or of one alone have probably acquired simple colour's, such as white or black, through sexual selection. The absence of bright tints or other ornaments may be the result of yariations of the right kind never having occurred, or of the animals themselves having preferred iDlain black or white. Obscure tints have often been developed through natural selection for the sake of protection, and the acquii-ement through sexual selection of conspicuous colours, appears to have been sometimes checked from the danger thus incurred. But in other cases the males during long ages may have struggled together for the possession of the females, and yet no effect will have been produced, unless a larger number of offspring were left by the more successful males to inherit their superiority, than by the less successful : and this, as previously shewn, depends on many complex contingencies. Sexual selection acts in a less rigorous manner than natural selection. The latter produces its effects by the life or death at all ages of the more or less successful individuals. Death, indeed, not rarely ensues from the conflicts of rival males. But generally the less successful male merely fails to obtain a female, or obtains a retarded and less vigorous female later in the season, or, if poly- gamous, obtains fewer females ; so that they leave fewer, less vigor- ous, or no offspring. In regard to structures acquired through ordinary or natural selection, there is in most cases, as long as the conditions of hfe remain the same, a limit to the amount of advantageous modification in relation to certain special purposes ; but in regai'd to structures adapted to make one male victorious over another, either in fighting or in charming the female, there is no definite limit to the amount of advantageous modification ; so that as long as the proper variations arise the work of sexual selection will go on. This circumstance may partly account for tlie frequent and extraordinary amount of variability presented CfiAP. VIII. Sexual Selection. 227 by secondary sexual characters. Nevertheless, natural selection -will determine that such characters shall not be acquired by the Tictorious males, if they would be highly injurious, either by expending too much of their vital powers, or by exposing them to any great danger. The development, however, of certain structures— of the horns, for instance, in certain stags — has been carried to a wonderful extreme ; and in some cases to an extreme which, as far as the general conditions of life are concerned, must be slightly injurious to the male. From this fact we learn that the advantages which favoured males derive from conquer- ing other males in battle or courtship, and thus leaving a numerous progeny, are in the long run greater than those derived from rather more perfect adaptation to their conditions of life. We shall further see, and it could never have been anticipated, that the power to charm the female has sometimes been more important than the power to conquer other males in battle. LAWS OF INHEIIITANCE. In order to understand how sexual selection has acted on many animals of many classes, and in the course of ages has produced a conspicuous result, it is necessary to bear in mind the laws of inheritance, as far as they are known. Two distinct elements are included under the term " inheritance " — the transmission, and the development of characters ; but as these generally go together, the distinction is often overlooked. We see this dis- tinction in those characters which are transmitted through the early years of life, but are developed only at maturity or during old age. We see the same distinction more clearly with secondary sexual characters, for these are transmitted through both sexes, though developed in one alone. That they are present in both sexes, is manifest when two species, having strongly-marked sexual characters, are crossed, for each trans- mits the characters proper to its own male and female sex to the liybrid offspring of either sex. The same fact is likewise mani- fest, when characters proper to the male are occasionally deve- loped in the female when she grows old or becomes diseased, as, for instance, when the common hen assumes the flowing tail- feathers, hackles, comb, spurs, voice, and even i^ugnacity of the cock. Conversely, the same thing is evident, more or less plainly, with castrated mal es. Again, independently of old age or disease, characters are occasionally transferred from the male to the female, as when, in certain breeds of the fowl, spurs regularly appear in the young and healthy females. But in truth they are simply developed in the female ; for in every breed each detail 228 The Descent of Man. Part II. in the structure of tlie spur is transmitted through the female to her male offspring. Many cases will hereafter be given, where the female exhibits, more or less perfectly, characters proper to the male, in whom they must have been first developed, and then transferred to the female. The converse case of the first de- velopment of characters in the female and of transference to the male, is less frequent ; it will therefore be well to give one strik- ing instance. With bees the pollen-collecting apparatus is used by the female alone for gathering pollen for the larvae, yet in most of the species it is partially developed -in the males to whom it is quite useless, and it is perfectly developed in the males of Bombus or the humble-bee.^^ As not a single other Hymenopterous insect, not even the wasp, which is closely allied to the bee, is provided with a pollen-collecting apparatus, we have no grounds for supposing that male bees primordially collected pollen as .well as the females ; although we have some reason to suspect that male mammals primordially suckled their young as well as the females. Lastly, in all cases of reversion, characters are transmitted through two, three, or many more generations, and are then developed under certain unknown favourable conditions. This important distinction between transmission and development will be best kept in mind by the aid of the hypothesis of pangenesis. According to this hypothesis, every unit or cell of the body throws off gemmules or undeveloped atoms, which are transmitted to the offspring of both sexes, and are multiphed by self-division. They may remain undeveloped during the early years of life or during successive generations; and their development into units or cells, like those from which they were derived, depends on their affinity for, and union with other units or cells previously developed in the due order of growth. Inheritance at corresponding Periods of Life. — This tendency is well established. A new character, appearing in a young animal, whether it lasts throughout life or is only transient, will,' in general, reappear in the offspring at the same age and last for the same time. If, on the other hand, a new character appears at maturity, or even during old age, it tends to re- appear in the offspring at the same advanced age. When devia- tions from this rule occur, the transmitted characters much oftenor appear before, than after the corj-esponding age. As I have dwelt on this subject sufficiently in another work,^^ I will ^- H. Miiller, ' Anweudung der ^^ 'The Variation of Animals Darwin'schen Lehre,' &c. Verb. and Plants under Domestication,' d. n. V. Jahrg. xxix. p. 42. vol. ii. 1868, p. 75. In the last Chap. Vlll. Sexual Selection. 229 here merely give two or three instances, for the sake of recalling the subject to the reader's mind. In several breeds of the Fowl, the down-covered chickens, the young birds in their first true X)limiage, and the adults differ greatly from one another, as well as from their common parent-form, the Gallus hankiva ; and these characters are faithfully transmitted by each breed to their offspring at the corresponding periods of life. For instance, the chickens of spangled Hamburg's, whilst covered with down, have a few dark spots on the head and rump, but are not striped longitudinally, as in many other breeds ; in their first true plu- mage, " they are beautifully pencilled," that is each feather is transversely marked by numerous dark bars ; but in their second plumage the feathers all become spangled or tipped with a dark round spot.^^ Hence in this breed variations have occurred at, and been transmitted to, three distinct periods of life. The Pigeon offers a more remarkable case, because the aboriginal parent species does not undergo any change of plumage with advancing age, excepting that at maturity the breast becomes more iridescent ; yet there are breeds which do not acquire their characteristic colours until they have moulted two, three, or four times ; and these modifications of plumage are regularly transmitted. Inheritance at corresponding Seasons of the Year. — With animals in a state of nature, innumerable instances occur of characters appearing periodically at different seasons. We see this in the horns of the stag, and in the fur of arctic animals which becomes thick and white during the winter. Many birds acquire bright colours and other decorations during the breeding-season alone. Pallas states,^^ that in Siberia domestic cattle and horses become lighter-coloured during the winter ; and I have myself observed, and heard of similar strongly marked changes of colour, that is, from brownish cream-colour or reddish-brown to a perfect white, in several ponies in England. Although I do not know that this tendency to change the colour of the coat during different seasons chapter but one, the provisional mals,' &c., vol. i. pp. 160, 249 ; hypothesis of pangenesis, above vol. ii. p. 77. alluded to, is fully explained. " ' Novte species Quadrupeduui e ^* These Aicts are given on the Glirium ordine,' 177 In regard to the Jews, see M. " prove that the higher male death- Thury, 'La Loi de Production des " rate is an impressed, natural, and Sexes,' 1863, p. 25. " constitutional peculiarity due to *^ ' British and Foreign Medico- " sex alone." Chirurg. Review,' April, 1867, p. 244 The Descent of Man. Part II. variable in structure than the female; and variations in im- portant organs would generally be injurious. But the size of the body, and especially of the head, being greater in male than female infants is another cause; for the males are thus more liable to be injured during parturition. Consequently the still- born males are more numerous ; and, as a higlily competent judge. Dr. Crichton Browne,^^ believes, male infants often suffer in health for some years after birth. Owing to this excess in the death- rate of male children, both at birth and for some time sub- sequently, and owing to the exposure of grown men to various dangers, and to their tendency to emigrate, the females in all old-settled countries, where statistical records have been kept,^^ are found to preponderate considerably over the males. It seems at first sight a mysterious fact that in different nations, under different conditions and cHmates, in Naples, Prussia, Westphalia, Holland, France, England and the United States, the excess of male over female births is less when they are illegitimate than when legitimate.^* This has been explained by different writers in many different ways, as from the mothers being generally young, from the large proportion of first preg- nancies, &c. But we have seen that male infants, from the large size of their heads, suffer more than fehiale infants diu'ing parturition ; and as the mothers of illegitimate children must be more liable than other women to undergo bad labours, from various causes, such as attempts at concealment by tight lacing, hard work, distress of mind, &c., their male infants would proportionably suffer. And this probably is the most eflaeient of all the causes of the proportion of males to females born alive being less amongst illegitimate children than amongst the legitimate. With most animals the greater size of the adult male than of the female, is due to the stronger males having conquered the weaker in their struggles for the possession of the females, and no doubt it is owing to this fact that the two sexes of at least some animals differ in size at birth. Thus *2 < West Riding Lunatic Asylum Paraguay, according to the accurate Reports,' vol. i. 1871, p. 8. Sir J. Azara ('Voyages dans I'Amerique Simpson has proved that the head merid.' tom. ii. 1809, p. 60, 179), of the male infant exceeds that of the women are to the men in the' the female by 3-8ths of an inch in proportion of 14 to 13. circumference, and by l-8th in ^^ Babbage, ' Edinburgh Journal transverse diameter. Quetelet has of Science,' 1829, vol. i. p. 88; also shewn that woman is born smaller p. 90, on still-born children. On than man; see Dr. Duncan, ' Fe- illegitimate children in England, cundity, Fertility, Sterility,' 1871, see 'Report of Registrar-General P- 382. for 1866,' p. xv. *^ With the savage Guaranys of Chap. VJII. Proportion of the Sexes. 245 M^e have the ctirions fact that we may attribute the more frequent deaths of male than female infants, especially amongst the illegitimate, at least in part to sexual selection. It has often been supposed that the relative age of the two parents determines the sex of the offspring ; and Prof. Leuckart^'^ has advanced what he considers sufficient evidence, with respect to man and certain domesticated animals, that this is one impor- tant though not the sole factor in the result. So again the period of impregnation relatively to the state of the female has been thought by some to be the efficient cause ; but recent observa- tions discountenance this belief. According to Dr. Stockton- nough,^6 the season of the year, the poverty or wealth of the parents, residence in the country or in cities, the crossing of foreign immigrants, &c., all influence the proportion of the sexes. With mankind, polygamy has also been supposed to lead to the birth of a greater proportion of female infants ; but Dr. J. Campbell ^^ carefully attended to this subject in the harems of Siam, and concludes that the proportion of male to female births is the same as from monogamous unions. Hardly ^ny animal has been rendered so highly polygamous as the English race- horse, and we shall immediately see that his male and female offspring are almost exactly equal in number. I will now give the facts which I have collected with respect to the proportional numbers of the sexes of various animals ; and will then briefly discuss how far selection has come into play in determining the result. Horses. — Mr. Tegetraeier Las been so kind as to tabulate for me from the ' Kacing Calendar ' the births of race-horses during a period of twenty-one years, viz., from 184G to 1867; 1849 being omitted, as no returns were that year published. The total births were 25,560,^* con- sisting of 12,763 males aiid 12,797 females, or iti tlie proportion of 997 males to 100 females. As these numbers are tolerably large, and as they are drawn from all parts of England, during several years,'we may with much confidence conclude that with the domestic horse, or at least with the race-horse, the two sexes are produced in almost equal numbers. The fluctuations in the proportions during successive years " Leuckart (in Wagner 'Hand- notice, as shewing how infertile wortorbuch der Phys.' B. iv. 1853, these highly-nurtured and rather s. 774. closely-inteibred animals have be- 5" Social Science Assoc, of Phila- come, that not far from one-third of delphia, 1874. the mares failed to produce living " ' Anthropological Review,' foals. Thus during 186G, 809 male April, 1870, p. cviii. colts and 816 female colts were born, ^8 During eleven years a record and 743 mares failed to produce was kept of the number of mares offspring. During 1867, 836 males which proved barren or prematurely and 902 females were born, and 794 slipped their foals ; and it deserves mares failed. 246 The Descent of Man. Part 11. are closely like those which occur with mankind, when a small and thinly-populated area is considered; thus in 1856 the male horses were as 107"1, and in 18o7 as only 92-6 to 100 females. In the tabulated returns the proportions vary in cycles, for the males exceeded the females during six successive years ; and the females exceeded the males during two periods each of four years : this, however, may be accidental ; at least I can detect nothing of the kind with man in the decennial table in the Eegistrar's Report for 1866. DoQs. — During a period of twelve years, from 1857 to 1868, the births of a large number of greyhounds, throughout England, were sent to the ' Field' newspaper ; and I am again indebted to Mr. Tegetmeier for carefully tabulating the results. The recorded births were 6878, consisting of 3605 males and 3273 females, that is, in the proportion of llO'l males to 100 females. The greatest fluctuations occurred in 1864, when the proportion was as 95-3 males, and in 1867, as 116-3 males to 100 females. The above average proportion of llO'l to 100 ia probably nearly correct in the case of the greyhound, but whether it would hold with other domesticated breeds is iu some degree doubtful. Mr. Cupples has enquired, from several great breeders of dogs, and iinds that all without exception believe that females are produced in excess; but he suggests that this belief may have arisen from females being less valued, and from the consequent disappointment producing a stronger impression on the mind. QUee-p. — The sexes of sheep are not ascertained by agriculturists until several months after birth, at the period when the males are castrated ; so that the following returns do not give the proportions at birth. Moreover, I find that several great breeders in Scotland, who annually raise some thousand sheep, are firmly convinced that a larger proportion of males than of females die during the first year or two. Therefore the proportion of males would be somewhat larger at birth than at the age of castration. This is a remarkable coincidence with what, as we ijave seen, occurs with mankind, and both cases probably depend on the same cause. I have received returns from four gentlemen in England who have bred Lowdand sheep, chiefly Leicesters, during the last ten to sixteen years; they amount altogether to 8965 births, consisting of 4407 males and 4558 females; that is in the proportion of 96 7 males to 100 females. With respect to Cheviot and black-faced sheep bred in Scotland, I have received returns from six breeders, two of them on a large scale, chiefly for the years 1867-1869, but some of the returns extend back to 1862. The total number recorded amounts to 50,685, consisting of 25,071 males and 25,614 females, or in the proportion of 97.9 males to 100 females. If we take the English and Scotch returns together, the total number amounts to 59,650, consisting of 29,478 males and 30,172 females, or as 97*7 to 100. So that with sheep at the age of castration the females are certainly in excess of the males, but probably this would not hold good at birth.^^ Of Cattle I have received returns from nine gentlemen of 982 births, too few to be trusted ; these consisted of 477 bull-calves and 505 cow- ^3 I am much indebted to Mr. tion to the premature deaths of the Cupples for having procured for me males, — a statement subsequently the above returns from Scotland, as confirmed by Mr. Aitcliison and well as some of the following re- others. To this latter gentleman, turns on cattle. Mr. R. Elliot, of and to Mr. Payan, I owe my thanks Laio-hwood, first called my atten- for large returns as to sheep. Chap. VIII. Proportion of the Sexes. l.X'j calves ; i.e., in the proportion of 91-4 males to 100 females. The Rev. W. D. Fox informs me that in 18G7 out of 84 calves born on a farm in Derbyshire only one was a bull. Mr. Harrison Weir has enquired from several breeders of P/(/.*, and most of them estimate the male to the female births as about 7 to 6. This same gentleman has bred liahhits for many years, and has noticed that a far greater number of bucks aie produced than does. But estimations are of little value. Of mammalia in a state of nature I have been able to learn very little. In regard to the common rat, I have received conflicting statements. Mr, R. Elliot, of Laighwood, informs me that a rat-catchei assured him that he had always found the males in great excess, even with the young in the nest. In consequence of this, Mr. Elliot Jiimself subsequently examined some hundred old ones, and found the statement true. Mr. F. Buckland has bred a large number of while rats, and he also believes that the males greatly exceed the females. Tn regard to Moles, it is said that " the males are much more numerous " than the females ;"^'' and as the catching of these animals is a special occupation, the statement may perhaps be trusted. Sir A. Smith, in describing an antelope of S. Africa*'^ (Kobus ellipsiprymnus), remarks, that in the herds of this and other species, the males are few in number compared with the females : the natives believe that they are born in this proportion ; others believe that the younger males arc expelled from the herds, and Sir A. Smith says, that though he has himself never seen herds consisting of young males alone, others affirm tiiat this does occur. It appears probable that the young when expelled from the herd, would often fall a prey to the many beasts of prey of the country. BIRDS. With respect to the Fowl, I have received only one account, namely, that out of 1001 chickens of a highly-bred fctock of Cochins, reared during eight years by Mr. Stretch, 487 proved males and 514 females; i.e., as 94-7 to 100. In regard to domestic pigeons tliere is good evidence either that the males are produced in excess, or that they live longer ; for these birds invariably pair, and single males, as Mr. Teget- raeier informs me, can always be purchased cheaper than females. Usually the two birds reared from the two eggs laid in the san\e nest are a male and a female ; but Mr. Harrison Weir, who has been so lar-^e a breeder, says that he has often bred two cocks from the same nest, and seldom two hens ; moreover, the hen is generally the weaker of the two, and more liable to perish. With respect to birds in a state of nature, Mr. Gould and others^^ are convinced that the males are generally the more numerous ; and as the young males of many species resemble the females, the latter would naturally appear to be the more numerous. Large numbers of pheasants are reared by Mr. Baker of Leadenhall from eggs laid by wild birds, and he informs Mr. Jenner Weir that four or five males to one female are generally produced. An experienced observer remarks." so Bell, * History of Briti.sh Quad- iv. s. 990) comes to the same oon- rupeds,' p. lUO. clu.sioa. 61 ' Illustrations of the Zoology e^ Qq j-j^g authority of L. Lloyd, of S. Africa,' 1849, pi. 29. 'Game Bird.s of Sweden,' 18G7, pp. 62 Brehm (' Illust. Thierleben,' B. 12, 133 248 T]ie Descent of Man. Paet II. that in Scandinavia the broods of the capercailzie and black-cock contain more males than females ; and that with the Dal-ripa (a kind of ptarmigan) more males than females attend the lelis or places of courtship ; but this latter circumstance is accounted for by some observers by a greater number of hen birds being killed by vermin. From various facts given by White of Selborne,"* it seems clear that the males of the partridge must be in considerable excess in the south of England ; and 1 have been assured that this is the case in Scotland. Mr. Weir on enquiring from the dealers, who receive at certain seasons large numbers of rufl's {Machetes pugnax), was told that the males are much the more numerous. This same naturalist has also enquired for me from the birdcatchers, who annually catch an astonishing number of various small species alive for the London market, and he was un- hesitatingly answered by an old and trustworthy man, that with the chaffinch the males are in large excess; he thought as high as 2 males to 1 female, or at least as high as 5 to 3.^^ The males of the blackbird, he likewise maintained, were by far the more numerous, whether • caught by traps or by netting at night. These statements may apparently be trusted, because this same man said that the sexes are about equal with the lark, the twite (^Linaria montana)^ and goldfinch. On the other hand, he is certain that with the common linnet, the females preponderate greatly, but unequally during different years ; during some years he has foimd the females to the males as four to one. It should, however, be borne in mind, that the chief season for catching birds does net begin till September, so that with some species partial migrations may have begun, and the flocks at this period often consist of hens alone. Mr. Salvin paid particular attention to the sexes of the humming-birds in Central America, and he is convinced that with most of the species the males are in excess; thus one year he procured 204 specimens belonging to ten species, and these consisted of 1G6 males and of only 38 females. With two other species the females were in excess : but the proportions apparently vary either during ditferent seasons or in difterent localities; for on one occasion the males of Campylopterus hemileucurus were to the females as 5 to 2, and on another occasion "^"^ in exactly the reversed ratio. As bearing on this latter point, I may add, that Mr. Powys found in Corfu and Epirus the sexes of the chaffinch keeping apart, and " the females by far the " most numerous;" whilst in Palestine Mr. Tristram found "the male '• flocks appearing greatly to exceed the female in number.""^' So again with the Quiscalus major, Mr. G. Taylor*** says, that in Florida there were " very few females in proportion to the males," whilst in Honduras the proportion was the other way, the species there having the character of a poiygamiot. " 'Nat. Hist, of Selborne,' letter ever caught by one man in a single xxix. edit, of 1825, vol. i. p. 139. day was 70. ®5 Mr. Jenner Weir received ^^ ' Ibis,' a'oI. ii. p. 260, as quoted similar information, on making en- in Gould's ' Trcchilidae,' 1861, p. quiries during the following year. 5'2. For the foregoing proportions, To shew the number of living chaf- I am indebted to Mr. Salvin for a finches caught, I may mention that table of his results. in 1869 the^re was a match between "^ 'Ibis,' 1860, p. 137; and 1867, two experts, and one man caught p. 369. in a day 62, and another 40, male "*' ' Ibis,' 1862, p. 137. chaffinches. The greatest number Chap. VIII. Proportion of the Sexes, 249 FISH. With Fish the proportional numbers of the sexes can be asfertnined only by catching them in the adult or neaily adult state ; and there are many difficulties in arriving at any just conclusion.'^^ Infertile fojuales might readily be mistaken for males, as Dr. Giinther has remarked to me in regard to trout. With some species the males are believed to die soon after fertilising the ova. Witli many species the mules are of much smaller size than the females, so that a large number of males would escape from the same net by which the females were caught. M. Carbounier/" who has especially attended to the natural history of the pike {E^x^x lucins), states that many males, owing to tiieir small size, are devoured by the larger females ; and he believes that the males of almost all fish are exposed from ihis same cause to greaier danger than the females. Nevertheless, in the few cases in which the proportional numbers have been actually observed, the males appear tj be largely in excess. Thus Mr. R. Uuist, the sujierin- tendent of the Stormontfield experiments, says that in 1865, out of 70 salmon first landed for the purpose of oblaining the ova, upwards of 60 were males. In 1867 he again " calls attention to the vast disproportion •' of the males to the females. We had at the outset at least ten males " to one female." Afterwards females sufficient for obtaining ova were procured. He adds, " from the great proportion of the males, they are "constantly fighting and tearing each other on the spawning-beds."^' This disproportion, no doubt, can be accounted for in part, but whether wholly is doubtful, by the males ascending the rivers before the females. Mr. F. Buckland remarks in regard to trout, that " it is a "curious fact that the males preponderate very largely in number over *' the females. It invariably happens that when the first rush of fish is " made to the net, there will be at least seven or ei^ht males to one "female found captive. I cannot quite account for this; either the *' males nre more numerous than the females, or the latter seek safety " by concealment rather than flight." He then adds, that by carefully searching the banks, sufficient females for obtaining ova can be found.'^ Mr. H. Lee informs me that out of 212 trout, taken for this purpose in Lord Portsmouth's park, 150 were males and 62 females. The males of the Cyprinidae likewise seem to be in excess ; but several members of this Family, viz., the carp, tench, brtam and minnow, appear regularly to follow the practice, rare in the animal kingdom, of polyandry ; for the female whilst spawning is always attended by two males, one on each side, and in the case of the bream by three or four males. This fact is so well known, that it is always recommended to stock a pond with two male tenches to one female, or at least with three males to two females. With the minnow, an excellent observer states, that on the spawning-beds the males are ten times as numerous as the females; when a female comes amongst the «3 Leuckart quotes Bloch (Wag- 18, 1869, p. 3G9. ner, ' Handworterbuch der Phys.' " ' The Stormontfield Piscicul- B. iv. 1853, s. 775), that with fish tural Experiments,' 186G, p. 23. there are twice as many males as The ' Field ' newspaper, June 29th, females. 1867. ^0 Quoted in the 'Farmer,' March " ' Land and Water,' 1868, p. 41. 12 250 The Descent of Man. Part 11. males, *' she is imraediatelj' pressed closely by a male oa each side ; "and when they have been in that situation for a time, are superseded " by other two males." "^ INSECTS. In this great Class, the Lepidoptera almost alone afford means for judging of the proportional numbers of the sexes ; for they have been collected with special care by many good observers,' and have been largely bred from the egg or caterpillar state. I had hoped that some breeders of silk-moths might have kept an exact record, but after writing to France and Italy, and consulting various treatises, I cannot hud that this has ever been done. Tiie general opinion appears to be that the sexes are nearly equal, but in Italy, as I hear from Professor Canestrini, many breeders are convinced that the females are produced in excess. This same naturalist, however, informs me, that in the two yearly broods of the Ailanthus silk-moth (Bomhijx cynthia), the males greatly preponderate in the first, whilst in the second the two sexes are nearly equal, or the females rather in excess. In regard to Butterflies in a state of nature, several obseivers have been much struck by the apparently enormous proponderance of the males.'^ Thus Mr. JBates,'^ in speaking of several species, about a hundred in number, which inhabit the Upper Amazons, says that the males are much more numerous than the females, even in the propor- tion of a hundred to one. In North America, Edwards, who had great experience, estimates in the genus Papilio the males to the females as four to one ; and Mr. Walsh, who informed me of this statement, says that with P. turims this is certainly the case. In South Africa, Mr. K. Trimen found the males in excess in 19 species ;"" and in one of these, which swarms in optn places, he estimated the number of males as fifty to one female. With another speoes, in which the males are numerous in certain localities, lie collected only five feuiales during seven years. In the island of Bourbon, M. IVLdllard states that the males of one species of Papilio are twenty times as numerous as the females.^^ Mr. Trimen informs me that as far as he has himself seen, or heard from others, it is rare for the females of any butterfly to exceed the males in number ; but three South African species per- haps oifer an exception. Mr. Wallace '* states that the females of Orintlwjjtera croesus, in the Malay archipelago, are more common and more easily caught than the males ; but this is a rare butterfly. I may ' " Yarrell, ' Hist. British Fishes,' or four times as numerous as the vol. i. 1826, p. 307 ; on the Cyprhvis females. ca/'jDiO, p. 331; on the Tmcavu/gram, " 'The Naturalist on the Ama- p. 331 ; on the Ahmmis braina, p. zons,' vol. ii. 18B3, p. 228, 347. 336. See, for the minnow (Leu- "« Four of the.se cases are given ciscus phoxin'is), ' Loudon's Mag. of by Mr. Trimen in his ' Rhopalocera Nat. Hist.' vol. v. 1832, p. 682. Africae Australis.' 7* Leuckart quotes Meinecke " Quoted by Trimen, ' Transact. (Wagner, ' Handworterbuch der Ent. Soc' vol. v. part iv. 1866, p. 330. Phys.' B. iv. 1853, s. 775) that '* ' Transact. Liun. Soc' vol. xxv. the males of Butterflies are three p. 37. Chap. VIII. Proportion of the Sexes. 251 here add, that in Hyperytlira, a genus of moths, Guenee says, that from four to five females are sent in collections from India for one male. When this subject of the proportional numbi^rs of the sexes of insects was brought before the Entomological Society,'" it was generally admitted that the males of most Leiiidoptera, in the adult or ima^io state, are caugijt in greater numbers than the females : but this fact was attributed by various observers to the more retiring habits of the females, and to the males emerging earlier from the cocoon. This latter circumstance is well known to occur with most Lepidoptcra. ns well as with other insects. So that, as M. Pcr.-^onnat remarks, the males of the domesticated Bombyx Yamamai, aie useless at the begin- ning of the Season, and the females at the end, from the want of mates.*" I cannot, however, persuade myself that these causes suffice to explain tl.e great excess of males, in the above cases of ccrtnin butter- flies which are extremely common in their native countries. Mr. Stainton, who has paid very close attention during many years to the smaller moths, informs- me that when he collected them in the imago state, he thought that the males were ten times as numerous as the females, but that since ho has reared them on a huge scale from the caterpillar state, he is convinced that the females are the liiore numerous. Several entomologists concur in this view. Mr. Double- day, however, and some others, take an opposite view, and are con- vinced that they have reared from tlie eggs and caterpillars a larger proportion of males than of females. Besides the more active habits of the males, their earlier emergence from the cucoon, and in some cases their frequenting more open stations, other causes may be assigned for an apparent or real difference in the propnrtional numbers of the sexes of Lepidoptera, when cap- tured in the imago state, and when reared from the egg or caterpillar state. I hear from Professor Canestrini, that it is believed by many breeders in Italy, that tiie female caterpillar of the silk-moth suffers more from the recent disease than the male ; and Dr. Staudinger informs me that in rearing Lepidoptera more females die in the cocoon than males. With many species the female caterpilliir is la'ger than the male, and. a collector would naturally choose the finest specimens, and thus unintentionally collect a larger number of females. Three collectors have told me that this was their practice ; but Dr. Wallace is sure that most collectors take all the specimens which they can find of the rarer kinds, which alone are worth the trouble of rearing. Birds when surrounded by caterpillars would probably devour the largest ; and Professor Canestrini inlbrms me that in Italy some breeders believe, though on insufficient evidence, that in the first broods of the Ailanthus siik-moth, the wasps destroy a larger number of the female than of the male caterpillars. Dr. Wallace further remarks that female caterpillars, from being larger than the males, require more time for their development, and consume more food and mois- ture ; and thus they would be exposed during a longer time to danger from ichneumons, birds, &c., and in times of scarcity would perish in greater numbers. Hence it appears quite possible that ^^ * Proc. Eutomolog. Soc' Feb. ' Proc. Eat. Soc' 3rd series, vol. v. I7th, 1868. 1867, p. 487. 8f Quoted by Dr. Wallace in 252 T J le Descent of Man, Pakt II. in a fctate of nature, fewer female LepidoptDra may reach maturity tiian males ; and for our special object we are concerned with their relative numbers at maturity, when the sexes are leady to propagate their land. The manner in which Iho males of certain moths congregjate in extraordinary numbers round a single female, apparently indicates a great excess of males, though this fact may perhaps bo accounted for by ihe earlier emergence of the males from their cocoons. Mr. Stainton informs me that from twelve to twenty males, may often be seen congregattd round a female Elachida rufocinerea. It is well known that if a virgin Lasiocampa quercus or Saiurnia carpiiti be exposed in a cage, vast numbers of males collect round her, and if confined in a room will even come down the chimney to htr. Mr. Doubleday believes that he has seen from iifty to a hundred males of both these species attracted in the course of a single day by a ft male in confinement. In the Isle of Wight Mr. Trimen exposed a box in which a female of the Lasiocampa hid. been confined on the previous day, and five males soon endeavoured to gain admittance. In Australia, M. Yerreuux, having placed the female of a small Bombyx in a box in his pocket, was followed by a crowd of males, so that about 200 entered the house with him.*^ Mr. Doubleday has called my attention to M. Staudinger's ®- litt of Lepidoptera, which gives the prices of the males and females of 300 species or well-marked varieties of butterflies (Ehopalocera). The prices for both sexes of the very common species are of course the same ; but in 114 of the rarer species they ditier; the males being in all cases, excepting one, the cheaper. On an average of the prices of the 113 species, the price of the male to that of the female is as 100 to 149 ; and this apparently indicates that inversely the males exceed the females in the same proportion. About 2000 species or varieties of moths (Heterocem) are catalogued, those with wingless females being here excluded on account of the difference in habits between the two sexes : of these 2000 species, 141 differ in price according t) i-ex, the males of 130 being cheaper, and those of oirly 11 being dearer than the females. The average price of the males of the 130 species, to that of the females, is as lOu to 143. With respect to the buttertiies in this priced litt, Mr. Doubleday thinks (and no man in England has had more experience), that there is nothing in the habit:, of the species which tan account for the difference in the prices of the two sexes, and that it Ciin be accounted for only by an excess in the number of the malts. But I am bound to add that Dr. Staudinger informs me, that he is h'mself of a different opinion. He thinks that the less active habits of the females and the earlier emergence of the males will account for his collectors securing a larger number of males than of females, and consequently for the lower prit-es of the former. With respect to specimens rtared from the caterpillar-state. Dr. Staudinger believes, as previously stated, that a greater number of females than of males die whilst confined in the cocoons. He adds that with certain species one sex seems to preponderate over the oth( r during certain ye.irs. Of direct observations on the sexes of Lepidoptera, reared either '^ Blanchard, ' Me'taraorphoses, ^^ ' Lepidopteren - Doubletten Moeurs des lasectes,' 1868, pp. 225- Liste,' Berlin, Ko. x. 1866. 226. Chap. VII I. Propo7'tion of the Sexes. 253 from eggs or caterpillars, I have received only the few following Males. ! Females. The Rev. J. Hellins*^ of Exeter reared, during 1868,|i imagos of 73 species, which consisted of. . ./j Mr. Albert Jones of Eltham reared, during 1868,^ imagos of 9 species, which consisted of . . . )\ During 18G9 he reared imagos from 4 species, con-i! sitting of /I Mr. Buckler of Emsworth, Hants, during 1869,11 reared imagos from 74: species, consisting of. . J 1 Dr. Wallace of Colchester reared from one brood of ll Bombyx cynthia j i Dr. Wallace raised, from cocoons of Bombyx Pernyin sent from China, during 1869 jj Dr. Wallace raised, during 1868 and 1869, from twolj lots of cocoons of Bombyx yama-mai . . .Jl Total 153 I 159 I 114 j ISO ; 224 i 934 I 137 126 112 169 48 123 46 761 So that in these eight lots of cocoons and eggs, males were produced in excess. Taken together the proportion of males is as \1tl to 100 females. Bat the numbers are hardly large enough to be trustworthy. On the whole, from these various sources of evidence, all pointing in the same direction, I infer that with most species of Lepidopteia, the mature males generally exceed the females in number, whatever the proportions may be at their first emergence from tlie o.^^^. \s\\\\ reference to the other Orders of insects, I have been able to collect very little reliable information. With the stag-l^ee le {Lucaiuis cervus) "tlie males appear to be much more numerous "than the females;" but when, as Cornelius remarked during 18(37, sin unusual number of these beetles appeared in one i)art of C'erinany, the females appeared to exceed the males as six to one. With one of the Elateridae, the males are said to be much more numerous than the females, and "two or thiee are often found united with one female ;^^ " so that here polyandry seems to prevail." With Siagonium (!St iphy- linidoe), in which the males are furnished with horns, " t .e females are " far more numerous than the opposite sex." Mr. Janson stated at the Entumological Society that the females of the btrk- feeding Tomicns villosus are so common as to be a plague, whilst the males are so rare jis to be hardly known. '^ This naturalist has been so kind as to send me some results from former years, in which the females seemed to preponderate ; but so many of the figures were estimates, that I found it impossible to tabulate them. ** Giinther's ' Record of Zoo- logical Literature,' 1867, p. 260. On the excess of female Liicanus, ibid. p. 250. On the males of Luca- nus in England, Westwood, 'Modern Class, of Insects,' vol. i. p. 187. On the Siagouium, ibid. p. 172. 254 1^^^ Desce7it of Man. Part II. It is liardly worth while saymg anything about the proportion of the sexes in certain spe 'ies and even groups of insects, for the males are unknown or very rare, and the females are parthenogenetic, that is, fertile without sexual rmion ; examples of this are afforded by several of the Cynipida^.*^ In all the gall-making Cynipidfe known to INIr. Walth, the females are four or live times as numerous as the males ; and so it i.s, as he informs me, with the gall-making Cecidomyiire (Diptera). With some common i-pecies of Saw-flies (Tenthredinai) Mr. F. Smith has reared hundreds of specimens from larvae of ail sizes, but has never reared a single male : c^n the other hand, Curtis say:<,*^ that with certain species (Athalia), bred by him, the males were t(» the females as six to one; whilst exactly the reverse occurred with the matiue insects of the same species caught in the fields. In the family of Bees, Hermann iMiiller.*^ collected a large number of specimens of mfiny s| ecies, and reared others from tl.e cocouns, and counted the texes. He found thut the males of some species gieatly exceeded the females in number ; in others the reverse occurred ; and in others the two sexes were nearly equal. But as in most cases the males emerge from the cocoons before the females, they are at the comme.'icement ,ot" the breeding seaton practically in excess. Miiller also observed that the relative number of the two sexes in s ^me species diftered much in different localities. But as H. Miiller has himself remarked to me, these remarks must be received with some caution, as one sex might more easily escape observation than the other. Thus his brother Fritz INIiiller has noticed in Brazil that the two sexes of the same species of bee sometimes frequent different kinds of lluwers. "With respect to the Orthoptera, I know hardly anything about the relative number cf the sexe^ : Korte,®^ however, says that out of 500 locusts which he examine 1, the males were to the females as five to six. With the Neuroptera, Mr. Walth states that in many, but by no means in all the species of the Odonatous group, there is a great overplus of males : in thg genus Heta^rina, also, the males are generally at least four times as numerous as the females. In certaiii species in the genus Gomphus the males are equally in excess, whilbt in two other spe 'ies, the females are twice or thrice as numerous as the males. In some European species of Psocus thousands of females may be collected without a single male, whilst with oilier species of the same genus both sexes are common,^^ In England, Mr. ]\IacLachlan has captured hundreds of the female Apatania muliebris, but has never seen t!,e male; and of Boreus hyfrtKilis on\j four or five males have been seen here."** With m<;8t of tin se species (excepting the Tenthredinre) there is at present no evidence that the females are subject to parthenogenesis; and thus we see how ignorant we are of the causes of the apparent discrepancy in the proportion of the two sexes. In ti.e other Classes of the Articulata I have been able to collect still 8^ Walsh, in 'The American En- derhenschrecke,' 1828, p. 20. tomologist,' vol. i. 1869, p. 103. *® ' Observations on X. American F. Smith, 'Record of Zoological Neuroptera,' by H. Hagen and B. D. Literature,' 1867, p. 328. Walsh, ' Proc. Ent. Soc. Phila- '"' ' Farm Insects,' pp. 45-46. delphia,' Oct. 1863, pp. 168, 223, *' * Anwendung der Darwinschen 239. Lehre Verb. d. n. V. Jahrg. x.xiv.' ^° ' Proc. Ent. Soc. London,' Feb. «8 'Die Strich, Zuir oder Wan- 17,1868. Chap. VIII. Proportion of the Sexes. 255 loss information. With Spiilers, Mr. Blackwall, who has carefully attended to this class during many years, writes to me that the male's from their more erratic habits are more commonly seen, and therefore appeur more numerous. This is actually the case with a few species ; but he mentions several species in six genera, in wiiich the females ap[)ear to be much more numerous than the males.**' 'I'he small size of the males in comparison with the females (a peculiarity which is some- times carried to an extreme degree), and their widely ditierent appear- ance, may account in some instances for their rarity in collections.''^ Some of the lower Crustaceans ai-e able to propigate their kind nsexually, and this v/ill account for the extreme larity of the males : thus Von SiebokP^ carefully examined no less than 1:3,000 specimens of Apus from twenty-one localities, and amongst these he found only 319 males. AV^itii some other forms (as Tanais and Cypris), as Fritz Miillt-r informs me, there is reason to believe that the males are much shorter-lived than the females ; and this would explain their scarcity, supposing the two sexes to be at first equal in number. On the other hand, Miiller has invariably taken far more males than females of the Diastylidc-e and of Cypridina on the shores of Brazil; thus witli a species in the latter genus, (33 specimens caught the same day included 57 males ; but he suggests that this preponderance may be due to some unknown difference in the habits of the two sexes. With one of the higher Brazilian crabs, n;tmely a Celasimus, Fritz Miiller found the males to be more numerous than the females. According to the Inrge experience of Mr. C. Spence Bate, the reverse seems to be the case with six common British crabs, the names of which he has given me. The proportion of the sexes in relation to natural selection. There is reason to suspect that in some cases man has by selection indirectly influenced his own sex-producing jwwers. Certain women tend to produce during their whole lives more children of one sex than of the other : and the same holds good of many animals, for instance, cows and horses ; thus Mr. Wright of Yelderslcy House informs me that one of his Arab mares, though put seven times to different horses, produced seven fillies. Though I have very little evidence on this head, analogy would lead to the belief, that the tendency to produce either sex would be inherited like almost every other peculiarity, for instance, that of producing twins ; and concerning the above tendency a good authority, Mr. J. Downing, has communicated to me facts which seem to prove that this does occur in certain families of short-horn cattle. Col. Marshall ^^ has recently found on careful examination that the Todas, a hill-tribe of India, ^* Another great authority with 0. P. Cambridge, as quoted in respect to this class, Prof. Thorell of 'Quarterly Journal of Science,' Upsala (' On European Spiders,' 18G8, p. 429. 1869-70, part i. p. 205) speaks as if ^^ i Beitrage zur Parthenogenesis,' female spiders wei'e generally com- p. 174. moner than the males. 9* * The Todas,' 1873, pp. 100, »2 See, on this subject, Mr, 111, 194, 196, 256 The Descent of Man. Part II. consist of 112 males and 84 females of all ages— that is in a ratio of 133-3 males to 100 females. The Todas, who are polyandrous in their marriages, during former times invariably practised female infanticide ; bnt this practice has now been discontinued for a considerable period. Of the children born within late years, the males are more numerous than the females, in the proportion of 121: to 100. Colonel Marshall accounts for this fact in the following ingenious manner. " Let us for the purpose of illustra- " tion take tln'ee families as I'epresenting an average of the " entire tribe ; say that one mother gives birth to six daughters '* and no sons ; a second mother has six sons only, whilst the " third mother has three sons and three daughters. The first " mother, following the tribal custom, destroys four daughters " and preserves two. The second retains her six sons. The third " kills two daughters and keeps one, as also her three sons. We " have then from the three families, nine sons and three daughters, " with which to continue the breed. But whilst the males " belong to families in which the tendency to produce sons is " great, the females are of those of a converse inclination. Thus " the bias strengthens with each generation, until, as we find, " families grow to have habitually more sons than daughters." That this result would follow from the above form of infanticide seems almost certain ; that is if we assume that a sex-producing tendency is inherited. But as the above numbers are so ex- tremely scanty, I have searched for additional evidence, but cannot decide whether wliat I have found is trustworthy ; nevertheless the facts are, i)erhaps, worth giving. The Maories of New Zealand have long practised infanticide ; and Mr. Fenton^^ states that he " has met with instances of women who have de- " stroyed four, six, and even seven children, mostly females. " However, the universal testimony of those best qualified to " judge, is conclusive that this custom has for many years been " almost extinct. Probably the year 1885 may be named as the " period of its ceasing to exist.'^ Now amongst the New Zea- landers, as with the Todas, male births are considerably in excess. Mr. Fenton remarks (p. 30), " One fact is certain, although the " exact period of the commencement of this singular condition of " the disproportion of the sexes cannot be demonstratively fixed, " it is quite clear that this course of decrease was in full opera- " tion during the years 1S30 to 1844, when the non-adult '' population of 1844 was being produced, and has continued " with great energy up to the present time." The following statements are taken from Mr. Fenton (jd, 26), but as the numbers ^^ 'Aboriginal Inhabitants of New Zealand ; Government Report,' 1859, p. 36. Chap. VIII. Proportion of the Sexes. 257 are not large, and as the census was not accurate, uniform results cannot be expected. It should be borne in mind in this and the following cases, that the normal state of every population is an excess of women, at least in all civilised countries, chiefly owing to the greater mortality of the male sex during youth, and partly to accidents of all kinds later in life. In 1858, the native population of New Zealand was estimated as consisting of 31,607 males and 21,303 females of all ages, that is in the ratio of 1303 males to 100 females. But during this same year, and in certain limited districts, the numbers were ascertained with much care, and the males of all ages were here 753 and the females 616 ; that is in the ratio of 122'2 males to 100 females. It is more important for us that during this same year of 1858, the non-adult males within the same district were found to be 178, and the uon-adidt females 142, that is in the ratio of 125*3 to 100. It may be added that in 1844, at which pariod female infanticide had only lately ceased, the nou-adult males in one district were 281, and the non-adult females only 191, that is in the ratio of 144-8 males to 100 females. In the Sandwich Islands, the males exceed the females in number. Infanticide was formerly practised there to a frightful extent, but was by no means confined to female infants, as is shewn by Mr. EUis,^'' and as I have been informed by Eishop Staley and the Eev. Mr. Coan. Nevertheless, another apparently trustworthy writer, Mr. Jarves,^^ whose observations apply to the whole archiiDelago, remarks: — "Numbers of women are to " be found, who confess to the murder of from three to six or eight " children ;" and he adds, " females from being considered less " useful than males were more often destroyed." From what is kno^vn to occur in other parts of the world, this statement is probable ; but must be received with much caution. The practice of infanticide ceased about the year 1819, when idolatry was abolished and missionaries settled in the Islands. A careful census in 1839 of the adult and taxable men and women in the island of Kauai and in one district of Oahu (Jarves, p. 404), gives 4723 males and 3776 females; that is in the ratio of 125'08 to 100. At the same time the number of males under fourteen years in Kauai and under eighteen in Oahu was 1797, and of females of the same ages 1429 ; and here we have the ratio of 12575 males to 100 females. In a census of all the islands in 1850,^*^ the males of all ages ^^ 'Narrative of a Tour through ^* This is given in the Rev. H. T. Hawaii,' 1826, p. 298. Cheever's ' Life in the Sandwich Is- »^ ' History of the Sandwich lands,' 1851, p. 277. Islands,' 1843, p. 93. 258 The Descent of Man. Paet II. amount to 36,272, and the females to 33,128, or as 109-49 to 100. The males under seventeen years amounted to 10,773, and the females under the same age to 9593, or as 112*3 to 100. From the census of lfe72, the proportion of males of all ages (including half-castes) to females, is as 125*36 to 100. It must be borne in mind that all these returns for the Sandwich Islands give the proportion of living males to living females, and not of the births ; and judging from all civilised countries the proportion of males would have been considerably higher it the numbers had referred to births.^^ From the several foregoing cases we have some reason to believe that infanticide practised in the manner above explained, tends to make a male-producing race ; but I am far from sup- posing that this practice in the case of man, or some analogous process with other species, has been the sole determining cause of an excess of males. There may be some unknown law leading to this result in decreasing races, which have already become somewhat infertile. Besides the several causes previously ^^ Dr. Coulter, in describing (' Journal R. Geograph. Soc.,' vol. V. 1835, p. 67) the state of Cali- fornia about the year 1830, says that the natives, reclaimed by the Spanish missionaries, have nearly all perished, or are perishing, al- though well treated, not driven from their native land, and kept from the use of spirits. He at- tributes this, in great part, to the undoubted fact that the men greatly exceed the women in number ; but he does not know whether this is due to a failure of female offspring, or to more females dying during early youth. The latter alternative, according to all analogy, is very improbable. He adds tiiat " in- " fanticide, properly so called, is " not common, though very fre- " quent recourse is had to abor- " tion." If Dr. Coulter is correct about infjinticide, this case cannot be advanced in support of Col. Marshall's view. From the rapid decrease of the reclaimed natives, we may suspect that, as in the cases lately given, their fertility has been diminished from changed habits of life. I had hoped to gain some light on this subject from the breeding of dogs; inasmuch as in most breeds, with the exception, perhaps, of greyhounds, many more female puppies are destroyed than males, just as with the Toda infants. Mr. Cupples assures me that this is usual with Scotch deer-hounds. Unfortunately, I know nothing of the proportion of the sexes in any breed, excepting greyhounds, and there the male births are to the female as 110-1 to 100. Now from enquiries made from many breeders, it seems that the females are in some respects more esteemed, though otherwise troublesome ; and it does not appear that the female puppies of the best-bred dogs are systematically destroyed more than the males, though this does sometimes take place to a limited extent. There- fore 1 am unable to decide whether we can, on the above principles, ac- count for the preponderance of male births in greyhounds. On the other hand, we have seen that with horses, cattle, and sheep, which are too valuable for the young of either sex to be destroyed, if (;here is any difference, the females are slightly in excess. Chap. VIII. Proportion of tJie Sexes. 259 alluded to, the greater facility of parturition amongst savages, and the less consequent injury to their male infants, would tend to increase the proportion of live-born males to females. There does not, however, seem to be' any necessary connection between savage life and a marked excess of males ; that is if we may judge by the character of the scanty offspring of the lately existing Tasmanians and of the crossed offspring of the Tahitians now inhabiting Norfolk Island. As the males and females of many animals differ somewhat in habits and are exposed in different degrees to danger, it is probable that in many cases, more of one sex than of the other are habitually destroyed. But as far as I can trace out the com- plication of causes, an indiscriminate though large destruction of either sex would not tend to modify the sex-producing power of the species. With strictly social animals, such as bees or ants, which produce a vast number of sterile and fertile females in comparison with the males, and to whom this preponderance is of paramount importance, we can see that those communities would flourish best which contained females having a strong inherited tendency to produce more and more females ; and in such cases an unequal sex-producing tendency would be ulti- mately gained through natural selection. With animals living in herds or troops, in which the males come to the front and defend the herd, as with the bisons of North America and certain baboons, it is conceivable that a male-producing tendency might be gained by natural selection ; for the individuals of the better defended herds would leave more numerous descendants. In the case of mankind the advantage arising from having a pre- ponderance of men in the tribe is supposed to be one chief cause of the practice of female infanticide. In no case, as far as we can see, would an inherited tendency to produce both sexes in equal numbers or to produce one sex in excess, be a direct advantage or disadvantage to certain individuals more than to others ; for instance, an individual with a tendency to produce more males than females would not succeed better in the battle for life than an individual with an opposite tendenc}'" ; and therefore a tendency of this kind could not be gained through natural selection. Nevertheless, there are certain animals (for instance, fishes and cirripedes) in which two or more males appear to be necessary for the fertilisation of the female ; and the males accordingly largely preponderate, but it is by no means obvious how this male-producing tendency could have been acquired. I formerly thought that when a tendency to produce the two sexes in equal numbers was advantageous to the species, it would follow from natural selection, but I now 26o The Descent of Man. Part II. see that the whole problem is so intricate that it is safer to leave its solution for the future. CHAPTER IX. Secondary Sexual Characters in the Lower Classes of THE Animal Kingdom. These characters absent in the lowest classes — Brilliant colours — MoUusca — Annelids — Crustacea, secondary sexual characters strongly developed ; dimorphism; colour; characters not acquired before maturity — Spiders, sexual colours of; stridulation by the males — Myriapoda. With animals belonging to the lower classes, the two sexes are not rarely united in the same individual, and therefore secondary sexual characters cannot be developed. In many cases where the sexes are separate, both are permanently at- tached to some support, and the one cannot search or struggle for the other. Moreover it is almost certain that these animals have too imperfect senses and much too low mental powers, to appreciate each other's beauty or other attractions, or to feel rivalry. Hence in these classes or sub-kingdoms, such as the Protozoa, Coelenterata, Echinodermata, Scolecida, secondary sexual cha- racters, of the kind which we have to consider, do not occur ; and this fact agrees with the belief that such characters in the higher classes have been acquired through sexual selection, which depends on the will, desire, and choice of either sex. Nevertheless some few apparent exceptions occur ; thus, as I hear from Dr. Eaird, the males of certain Entozoa, or internal parasitic worms, differ slightly in colour from the females ; but we have no reason to suppose that such differences have been augmented through sexual selection. Contrivances by which the male holds the female, and which are indispensable for the propagation of the species, are independent of sexual selection, and have been acquired through ordinary selection. Many of the lower animals, whether hermaphrodites or with separate sexes, are ornamented with the most brilliant tints, or are shaded and striped in an elegant manner ; for instance, many corals and sea-anemones (Actiniae), some jelly-fish (Medusae, Porpita, &c.), some Planarise, many star-fishes. Echini, Ascidians, &c. ; but we may conclude from the reasons already indicated, namely the union of the two sexes in some of these animals, the permanently affixed condition of others, and the low mental powers of all, that such colours do not serve as a sexual attraction, and have not been acquired through sexual selection. Chap. IX. Sexual Selection. 26 1 It should be borne in mind that in no case have we suffi- cient evidence that colours have been thus acquired, ex- cept where one sex is much more brilliantly or conspicuously coloured than the other, and where there is no difference in habits between the sexes sufficient to account for their different colours. But the evidence is rendered as complete as it can ever be, only when the more ornamented indivi- duals, almost always the males, voluntarily display their attractions before the other sex ; for we cannot believe that such display is useless, and if it be advantageous, sexual selection will almost inevitably follow. AVe may, however, extend this conclusion to both sexes, when coloured alike, if their colours are plainly analogous to those of one sex alone in certain other species of the same group. How, then, are we to account for the beautiful or even gorgeous colours of many animals in the lowest classes? It appears doubtful whether such colours often serve as a protec- tion ; but that we may easily err on this head, will be admitted by every one who reads Mr. Wallace's excellent essay on this subject. It would not, for instance, at first occur to auy one that the transparency of the Medusae, or jelly-fishes, is of the highest service to them as a protection; but when we are reminded by Hackel that not only the medusae, but many floating mollusca, crustaceans, and even small oceanic fishes partake of this same glass-like appearance, often accompanied by prismatic colours, we can hardly doubt that they thus escape the notice of pelagic birds and other enemies. M. Girard is also convinced ^ that the bright tints of certain sponges and ascidians serve as a protection. Conspicuous colours are likewise beneficial to many animals as a warning to their would-be devourers that they are distasteful, or that they possess some special means of defence ; but this subject will be discussed more conveniently hereafter. We can, in our ignorance of most of the lowest animals, only say that their bright tints result either from the chemical nature or the minute structure of their tissues, independently of any benefit thus derived. Hardly any colour is finer than that of arterial blood; but there is no reason to suppose that the colour of the blood is in itself any advantage; and though it adds to the beauty of the maiden's cheek, no one will pretend that it has been acquired for this purpose. So again with many animals, especially the lower ones, the bile is richly coloured ; thus, as I am informed by Mr. Hancock, the extreme beauty of the Eolidae (naked sea-slugs) is chiefly due to the biliary glands ' 'Archives dc Zoolog. Exper.,' Oct. 1872, p. 563. 262 The Descejit of Man, Part U. being seen through the translucent integuments — this beauty being probably of no service to these animals. The tints of the decaying leaves in an American forest are described by every one as gorgeous; yet no one supposes that these tints are of the least advantage to the trees. Bearing in mind how many substances closely analogous to natural organic compounds have been recently formed by chemists, and which exhibit the most splendid colours, it would have been a strange fact if substances similarly coloured had not often originated, independently of any useful end thus gained, in the complex laboratory of living organisms. The sub-kingdom of the Mollusca. — Throughout this great division of the animal kingdom, as far as I can discover, secondary sexual characters, such as we are here considering, never occur. Nor could they be expected in the three lowest classes, namely in the Ascidians, Polyzoa, and Brachiopods (constituting the Molluscoida of some authors), for most of these animals are permanently affixed to a support or have their sexes united in the same individual. In the Lamellibranchiata, or bivalve shells, hermaphroditism is not rare. In the next higher class of the Gasteropoda, or univalve shells, the sexes are either united or separate. But in the latter case the males never possess special organs for finding, securing, or charming the females, or for fighting with other males. As I am informed by Mr. Gwyn Jeffreys, the sole external difference between the sexes consists in the shell sometimes differing a little in form ; for instance, the shell of the male periwinkle {LUtorina littorea) is narrower and has a more elongated spire than that of the female. But differences of this nature, it may be presumed, are directly connected with the act of reproduction, or with the development of the ova. The Gasteropoda, though capable of locomotion and furnished with imperfect eyes, do not appear to be endowed with sufficient mental powers for the members of the same sex to struggle together in rivalry, and thus to acquire secondary sexual characters. Nevertheless with the pulmoniferous gasteropods, or land-snails, the pairing is preceded by courtship; for these animals, though hermaphrodites, are compelled by their structure to pair together. Agassiz remarks,^ " Quiconque a eu I'occasion " d'observer les amours des lima9ons, ne saurait mettre en doute " la seduction deployee dans les mouvements et les allures qui " preparent et accomplissent le double embrassement de ces " hermaphrodites." These animals appear also susceptible of some degree of permanent attachment : an accurate observer, * ' De I'Espece et de la Class.' &c., 1869, p. 106. Chap. IX. Molluscs. 263 Mr. Lonsdale, informs me that he placed a pair of land-snails, {Hdix j>omatia), one of which was weakly, into a small and ill- provided garden. After a short time the strong and healthy individual disappeared, and was traced by its track of slime over a wall into an adjoining well-stocked garden. Mr. Lonsdale concluded that it had deserted its sickly mate; but after an absence of twenty-four hours it returned, and apparently communicated the result of its successful exploration, for both then started along the some track and disappeared over the wall. Even in the highest class of the Mollusca, the Cephalopoda or cuttlefishes, in which the sexes are separate, secondary sexual characters of the present kind do not, as far as I can discover, occur. This is a surprising circumstance, as these animals possess highly-developed sense-organs and have considerable mental powers, as will be admitted by every one who has watched their artful endeavours to escape from an enemy.^ Certain Cephalopoda, however, are characterised by one extraordinary sexual character, namely, that the male clement collects within one of the arms or tentacles, which is then cast off, and clinging by its sucking-discs to the female, lives for a time an independent life. So completely does the cast-off arm resemble a separate animal, that it was described by Cuvier as a parasitic worm under the name of Plectocolyle. But this marvellous structure may be classed as a primary rather than as a secondary sexual character. Although with the Mollusca sexual selection does not seem to have come into play; yet many univalve and bivalve shells, such as volutes, cones, scallops, &c., are beciutifully coloured and shaped. The colours do not appear in most cases to be of any use as a protection ; they are probably the direct result, as in the lowest classes, of the nature of the tissues ; the patterns and the sculpture of the shell depending on its manner of growth. The amount of light seems to be influential to a certain extent; for although, as repeatedly stated by Mr. Gwyn Jeffreys, the shells of some species living at a profound depth are brightly coloured, yet we generally see the lower surfaces, as well as the parts covered by the mantle, less highly-coloured than the upper and exposed surfaces.-* In some cases, as with shells 3 See, for instance, the account influence of light on the colours of which I have given in my 'Journal a I'rondescent incrustation, de- of Researches,' 1845, p. 7. posited by the surf on the coast- * I have given (' Geolog. Obser- rocks of Ascension, and formed by vations on Volcanic Islands,' 18+4, the solution of triturated sea-shells, p. 53) a curious instance of the 264 The DesccJit of Man. Fart II. living amongst corals or briglitly-tinted sea-weeds^ the bright colours may serve as a protection.^ But that many of the nudi- brancli mollusca, or sea-slugs, are as beautifully coloured as any shells, may be seen in Messrs. Alder and Hancock's magnificent work ; and from information kindly given me by Mr. Hancock, it seems extremely doubtful whether these colours usually serve as a protection. With some species this may be the case, as with one kind which lives on the green leaves of algse, and is itself bright-green. But many brightly-coloured, white or otherwise conspicuous species, do not seek concealment ; whilst again some equally conspicuous species, as well as other dull-coloured kinds, live under stones and in dark recesses. So that with these nudi- branch molluscs, colour apparently does not stand in any close relation to the nature of the places which they inhabit. These naked sea-slugs are hermaphrodites, yet they pair together, as do land-snails, many of which have extremely pretty shells. It is conceivable that two hermaphrodites, attracted by each other's greater beauty, might unite and leave offspring which would inherit their parents' greater beauty. But with such lowly-organised creatures this is extremely improbable. Nor is it at all obvious how the offspring from the more beautiful pairs of hermaphrodites would have any ad- vantage over the offspring of the less beautiful, so as to increase in number, unless indeed vigour and beauty generally coincided. We have not here the case of a number of males becoming mature before the females, with the more beautiful males selected by the more vigorous females. If, indeed, brilliant colours were beneficial to a hermaphrodite animal in relation to its general habits of life, the more brightly-tinted individuals would succeed best and would increase in number ; but this would be a case of natural and not of sexual selection. Sub-kingdom of the Vermes: Class, Annelida (or Sea-ivorms). — In this class, although the sexes, when separate, sometimes differ from each other in characters of such importance that they have been placed under distinct genera or even families, yet the differences do not seem of the kind which can be safely at- tributed to sexual selection. These animals are often beauti- fully coloured, but as the sexes do not differ in this respect, we are but little concerned with them. Even the Nemertians, though so lowly organised, " vie in beauty and variety of " colouring with any other group in the invertebrate series;" yet ^ Dr. Morse has lately discussed ' Proc. Boston Soc. of Nat. Hist.' this subject in his paper on the vol. xiv., April, 1871. Adaptive Coloration of Mollusca, Chap. IX. Crustaceaiis, 265 Dr. Mcintosh" cannot discoTcr that these colours are of any service. The sedentary annelids become dnller-colonred, ac- cording to M. Quatrefages/ after the period of reproduction ; and this I presume may be attributed to their less vigorous condition at that time. All these-worm-like animals apparently stand too low in the scale for the individuals of either sex to exert any choice in selecting a partner, or for the individuals of the same sex to struggle together in rivalry. Suh-hingdom of the Arthropoda : Class, Crustacea, — In this great class we first meet with undoubted secondary sexual characters, often developed in a remarkable manner. Unfortunately the habits of crustaceans are very imx^erfectly known, and we cannot explain the uses of many structures i3eculiar to one sex. With the lower i^arasitic species the males are of small size, and they alone are furnished with perfect swimming-legs, antennse and sense-organs ; the females being destitute of these organs, with their bodies often consisting of a mere distorted mass. But these extraordinary differences between the two sexes are no doubt related to their widely different habits of life, and con- sequently do not concern us. In various crustaceans, belonging to distinct families, the anterior antennae are furnished with Xjeculiar thread-like bodies, which are believed to act as smelling-organs, and these are much more numerous in the males than in the females. As the males, without any unusual development of their olfactory organs, would almost certainly be able sooner or later to find the females, the increased number of the smelling- threads has probably been acquired through sexual selection, by the better provided males having been the more successful in finding partners and in producing offspring. Fritz Miiller lias described a romarkable dimorphic species of Tanais, in which the male is represented by two distinct forms, which never graduate into each other. In the one form the male is furnished with more numerous smelling-threads, and in the other form with more powerful and more elongated chelse or pincers, which serve to hold tlie female. Fritz Miiller suggests that these differences between the two male forms of the same species may have originated in certain individuals having varied in the number of the smelling-threads, whilst other individuals varied in the fthape and size of their chelae ; so that of the former, those which were best able to find the female, and of the latter, those v/hich • See his beautiful monograph on ^ See M. Perrier, ' I'Origine de * British Annelids,' part i. 1873, I'Homme d'apres Darwin,' ' Kevue p. 3. Scientifique,' Feb. 1873, p. 8G6. 266 The Descent of Man. Part II. were best able to hold her, have left the greatest number of progeny to inherit their respective advantages.^ In some of the lower crustaceans, the right anterior antenna of the .male differs greatly in structure from the left, the latter resembling in its simple tapering joints the antennsB of the female. In the male the modified antenna is either swollen in the middle or angularly bent, or converted (fig. 4) into an elegant, and sometimes wonderfully complex, prehensile organ.^ It serves, as I hear from Sir J. Lubbock, to hold the female, and for this same purpose one of the two posterior legs (6) on the same side of the body is converted into a forceps. In another family the inferior or . posterior antennsB are '' curiously zigzagged " in the males alone. In the higher crustaceans the an- terior legs are developed into chelae or pincers; and tlicse are generally larger in the male than in the female, — so much so that the market value of the male edible crab (^Caiicer jpagurus), according to IMr. C. Spence Bate, is five times as great as that of the fe- male. In many species the chelse are of unequal size on the opposite side of the body, the right-hand one being, as I am informed by Mr. Bate, generally, though not invariably, the largest. This inequality is also often much greater in the male than in the female. The two chelae of the male often differ in structure (figs. 5, 6, and 7), the smaller one resembling that of the female. What advantage is gained by their inequality in size on the opposite sides of the 4. LabWocera Darwinii (from Lubbock). a. Part of right anterior an- tenna of male, forming a prehensile organ. b. Posterior pair of thoracic legs of male. c. Ditto of temale. * * Facts and Arguments for Darwin,' English translat. 1869, p. 20. See the pi-evious discussion on the olfactory threads. Sars has described a somewhat analogous case (as quoted in * Nature,' 1870, p. 455) in a Norwegian crustacean, the Poiitoporeia affinis. ^ See Sir J. Lubbock in ' Annals and Mag. of Nat. Hist.' vx)l. xi. 1853, pi. i. and x. ; and vol. xii. (1853) pi. vii. See also Lubbock in 'Transact. Ent. Soc' vol. iv. new series, 1856-1858, p. 8. With re- spect to the zig-zagged antennjE mentioned below, see Fritz Miiller, ' Facts and Arguments for Darwin,' 1869, p. 40, foot-note. Chap. IX. Crjistaceans. 267 body, and by the inequality being much greater in the male than in the female ; and why, when they are of equal size, both aro Fig. 5. Anterior part of body of Callianassa (from Milne-Edwards), showing the un- equal and dififerently-coustructed right and left-hand chela? of the male. N.B— The artist by mistake has reversed the drawing, and made the left-hand chela the largest. Fig. 6. Fig. 7. Fig. 6. Fig. Y. Second leg of male Orchestia Tucuratinga (from Fritz MUller). Ditto of female. often much larger in the male than in the female, is not known. As 1 hear from Mr. Bate, the chelae are sometimes of such length and size that they cannot possibly be used for carrying food to the mouth. In the males of certain fresh-water prawns (Palsemon) the right leg is actually longer than the whole body.^° The gr3at size of the one leg with its chela3 may aid the male in fighting with his rivals; but this will not account for their *" See a paper by ^Ir. C. Spence Bate, with figures, in ' Proc. Zoolosj. See' 1868, p. 363 ; and on the nomenclature of the genus, ibid. p. 585. I am greatly indebted to Mr. Spence Bate for nearly all the above statements with respect to the chelae of the higher crustaceans. 268 T]ie Descent of Man. Part II. inequality in the female on the opposite sides of of the body. In Gelasimus, according to a statement quoted by Milne-Edwards," the male and the female live in the same bnrrow, and this shews that they pair ; the male closes the month of the burrow with one of its chelre, which is enormously developed ; so that here it indirectly serves as a means of defence. Their main use, however, is probably to seize and to secure the female, and this in some instances, as with Gammarus, is known to be the case. The male of the hermit or soldier crab {Fafiurus) for weeks together, carries about the shell inhabited by the female. ^^ The sexes, however, of the common shore-crab (Carcinus manas), as Mr. Bate informs me, unite directly after the female has moulted her hard shell, when she is so soft that she would be injured if seized by the strong pincers of the male ; but as she is caught and carried about by the male before moulting, she could then be seized with impunity. Fritz Muller states that certain species of Melita are distin- guished from all other amphipods by the females having " the " coxal lamellae of the penultimate pair of feet produced into " hook-like processes, of which the males lay hold with the *' hands of the first pair." The develojDment of these hook-like processes has probably followed from those females which were the most securely held during the act of reproduction, having left the largest number of offspring. Another Brazilian amphi- pod (Oichestia Darwinii, fig. 8) presents a case of dimorphism, like that of Tanais ; for there are two male forms, which differ in the structure of their chelse.^^ As either chela would certainly suffice to hold the female, — for both are now used for this purpose, — the two male forms probably originated by some having varied in one manner and some in another ; both forms having derived certain special, but nearly equal advantages, from their differently shaped organs. It is not known that male crustaceans fight together for the possession of the females, but it is probably the case ; for with most animals when the male is larger than the female, he seems to owe his greater size to his ancestors having fought with other males during many generations. In most of the orders, especially in the highest or the Brachyura, the male is larger than the female ; the parasitic genera, however, in which the sexes follow different habits of life, and most of the Ento- mostraca must be excei)ted. The cheljB of many crustaceans are " *Hist. Nat. des Crust.' torn. ii. of S. Devon.' 1837, p. 50. ^^ Fritz Miiller, ' Facts and Argu- >2 Mr. C. Spence Bate, * Brit. ments for Darwin,' 1869, pp. 25-28 Assoc, Fourth Report on the Fauna Chap. IX. Criistacemis. 269 ■weapons well adapted for fighting. Tluis when a Devil-crab {Portunus pubcr) was seen by a son of Mr. Bate fighting with a Carcinus mcenas, the latter was soon thrown on its back, and had every limb torn from its body. When several males of a Brazilian Gelasimns, a species furnished with immense pincers, were placed together in a glass vessel by Fritz Miiller, they mutilated and killed one another. Mr. Bate put a large male Carcmus Fig. 8. Orchestia Darwinii (from Fritz Miiller), showing the differently-constructed cheltB uf the two male forms. mcenas into *a pan of water, inhabited by a female which was paired with a smaller male ; but the latter was soon dispossessed. 2/0 The Descent of Man. Part II. Mr. Bate adds, '' if they fought, the victory was a bloodless one, " for I saw 110 wounds." This same naturalist separated a male sand-skipper (so common on our sea-shores), Gammarus marmus, from its female, both of whom were imprisoned in the same vessel with many individuals of the same species. The female, when thus divorced, soon joined the others. After a time the male Avas put again into the same vessel ; and he then, after swimming about for a time, dashed into the crowd, and without any fighting at once took away his wife. This fact shews that in the Amphipoda, an order low in the scale, the males and females recognise each other, and are mutually attached. The mental powers of the Crustacea are i^robably higher than at first sight appears probable. Any one who tries to catch one of the shore-crabs, so common on tropical coasts, will perceive how wary and alert they 'are. There is a large crab {Binjus latro), found on coral islands, which makes a thick bed of the picked fibres of the cocoa-nut, at the bottom of a deep burrow. It feeds on the fallen fruit of this tree by tearing off the husk, fibre by fibre ; and it always begins at that end where the three eye-like depressions are situated. It then breaks through one of these eyes by hammering with its heavy front pincers, and turning round, extracts the albuminous core with its narrow posterior pincers. But these actions are probably instinctive, so that they would be performed as well by a young animal as by an old one. The following case, however, can hardly be so con- sidered : a trustworthy naturalist, Mr. Gardner,^^ whilst watching a shore-crab (Gelasimus) making its burrow, threw some shells towards the hole. One rolled in, and three other shells remained within a few inches of the mouth. In about five minutes the crab brought out the shell which had fallen in, and carried it away to the distance of a foot ; it then saw the three other shells lying near, and evidently thinking that they might likewise roll in, carried them to the spot where it had laid the first. It would, I think, be difi&cnlt to distinguish this act from one performed by man by the aid of reason. Mr. Bate does not know of any well-marked case of difference of colour in the two sexes of our British crustaceans, in which respect the sexes of the higher animals so often differ. In some cases, however, the males and females differ slightly in tint, but Mr. Bate thinks not more than may be accounted for by their different habits of life, such as by the male wandering more about, and being thus more exposed to the light. Dr. Power ** ' Travels in the Interior of 463, un account of the hiibits of the Brazil,' 1846, p. 111. I have given, Birgus. in my ' Joui-nal of Researches,' p. Chap. IX. Crustaceans. 2/1 tried to distinguish by colour the sexes of the several species which inhabit the Mauritius, but failed, except with one species of Squilla, probably .S'. stylifera, the male of which is described as being" of a beautiful bluish-green," with some of the appendages cherry-red, whilst the female is clouded with brown and grey, " with the red about her much less vivid than in the male." '^ In this case, we may suspect the agency of sexual selection. From M. Bert's observations on Daphnia, when placed in a vessel illuminated by a prism, we have reason to believe that even the lowest crustaceans can distinguish colours. With Saphirina (an oceanic genus of Entomostraca), the males are furnished with minute shields or cell-hke bodies, which exhibit beautiful changing colours ; these are absent in the females, and in both sexes of one species.^*^ It would, however, be extremely rash to conclude that these curious organs serve to attract the females. I am informed by Fritz Miiller, that in the female of a Brazilian species of Gelasimus, the whole body is of a nearly uniform greyish-brown. In the male the posterior part of the cephalo-thorax is pure white, with the anterior part of a rich green, shading into dark brown ; and it is remarkable that these colours are liable to change in the course of a few minutes — the white becoming dirty grey or even black, the green " losing much " of its brilliancy." It deserves especial notice that the males do not acquire their bright colours until they become mature. They appear to be much more numerous than the females; they differ also in the larger size of their chelae. In some species of the genus, probably in all, the sexes pair and inhabit the same burrow. They are also, as we have seen, highly intelligent animals. From these various considerations it seems probable that the male in this species has become gaily ornamented in order to attract or excite the female. It has just been stated that the male Gelasimus does not acquire his conspicuous colours until mature and nearly ready to breed. This seems a general rule in the whole class in respect to the many remarkable structural differences between the sexes. We shall hereafter find the same law prevailing throughout the great sub-kingdom of the Vertebrata ; and in all cases it is eminently distinctive of characters which have been acquired through sexual selection. Fritz Miiller ^^ gives some striking instances of this law ; thus the male sand-hopper (Orchestia) does not, until nearly full grown, acquire his large claspers, *^ Mr. Ch. Fraser, in * Proc. Zoo- '* Claus, ' Die freilebenden Cope- log. Soc' 1869, p. 3. I am indebted poden,' 1863, s. 35. to Mr. Bate for Dr. Power's state- '^ ' Facts and Arguments,' &c., ment. p. 79. 2/2 TJie Descent of Man. Part II. which are yery differently constructed from those of the female ; whilst young, his claspers resemble those of the female. Class, Arachnida (Spiders). — The sexes do not generally differ much in colour, but the males are often darker than the females, as may be seen in Mr. Blackwall's magnificent work.^** In some species, however, the difference is conspicuous : thus the female of Sjmrassus smaragdidus is dullish green, whilst the adult male has the abdomen of a fine yellow, with three longitudinal stripes of rich red. In certain species of Thomisus the sexes closely resemble each other, in others they differ much ; and analogous cases occur in many other genera. It is often difficult to say which of the two sexes departs most from the ordinary coloration of the genus to which the species belong ; but Mr. Blackwall thinks that, as a general rule, it is the male ; and Canestrini ^^ remarks that in certain genera the males can be specifically dis- tinguished with ease, but the females with great difficulty. I am informed by Mr. Blackwall that the sexes whilst young usually resemble each other ; and both often undergo gi-eat changes in colour during their successive moults, before arriving at maturity. In other cases the male alone appears to change colour. Thus the male of the above bright-coloured Sparassus at first re- sembles the female, and acquires his peculiar tints only when nearly adult. SjDiders are j)ossessed of acute senses, and exliibit much intelligence ; as is well known, the females often shew the strongest affection for their eggs, wliich they carry about enveloped in a silken web. The males search eagerly for the females, and have been seen by Canestrini and others to fight for possession of them. This same author says that the union of the two sexes has been observed in about twenty species ; and he asserts positively that the female rejects some of the males who court her, threatens them with open mandibles, and at last after long hesitation accepts the chosen one. From these several considerations, we may admit with some confidence that the well-marked differences in colour between the sexes of certain species are the results of sexual selection ; though we have not here the best kind of evidence, — the display by the male of his ornaments. From the extreme variability of colour in the male of some sjDecies, for instance of Theridion llneatum, it would appear that these sexual characters of the males have not as yet become well fixed. Canestrini draws the same conclusion from '* • A. History of the Spiders of ' Caratteri sessuali secondarii degli Great Britain,' 1861-G4-. For the Arachnidi,' in the 'Atti della See. fcllowiug facts, see pp. 77, 88, 102. Veneto-Trentiua di Sc. Nat. Padova, '^ This author has recentfy pub- vol. i. Fasc. 3, 1873. lishod a valuable essay on the Chap. IX. Spiders. 273 the fact that the males of certain species present two forms, differing from each other in the size and length of their jaws ; and this reminds us of the above cases of dimorphic crustaceans. The male is generally much smaller than the female, sometimes to an extraordinary degree,-" and he is forced to be extremely cautious in making his advances, as the female often carries her coyness to a dangerous pitch. De Geer saw a male that " in the " midst of his preparatory caresses was seized by the object of " his attentions, enveloped by her in a web and then devoured, a " sight which, as he adds, filled him with horror and indignation." ^^ The Eev. 0. P. Cambridge ^^ accounts in the following manner for the extreme smalhiess of the male in the genus Nephila. " M. Vinson gives a gTaphic account of the agile way in which " the diminutive male escapes from the ferocity of the female, by " gliding about and playing hide and seek over her body and " along her gigantic limbs : in such a pursuit it is evident that " the chances of escape would be in favour of the smallest males, " while the larger ones would fall early victims ; thus gradually " a diminutive race of males would be selected, until at last they " would dwindle to the smallest possible size compatible with the " exercise of their generative functions, — in fact probably to the " size we now see them, i.e., so small as to be a sort of parasite " upon the female, and either beneath her notice, or too agile and " too small for her to catch without great difficulty." Westring has made the interesting discovery that the males of several species of Theridion^ have the power of making a stridulating sound, whilst the females are mute. The ap- paratus consists of a serrated ridge at the base of the abdomen, against wliich the hard hinder part of the thorax is rubbed ; and of this structure not a trace can be detected in the females. It deserves notice that several writers, including the well-known arachnologist Walckenaer, have declared that spiders are attracted by music.^* From the analogy of the Orthoptera and Homoptera, -" Aug. Vinson (' Araneides des tion to Entomology,' vol. i. 1818, lies de la Reunion/ pi. vi. figs. 1 p. 280. and 2) gives a good instance of the ^^ 'Proc.Zoolog. Soc' 1871, p. 621. small size of the male, in Epeira ^s Jheridion (Asagena, Sund.) nigra. In this species, as I may serratipes, A-punctatum ct gutta- add, the male is testaceous and the turn ; see Westring, in Kroyer, female black with legs banded with ' Naturhist. Tidslcrift,' vol. iv. 1842- red. Other even more striking 1843, p. 349; and vol. ii. 1846-- cases of inequality in size between 1849, p. 342. See, also, for other the sexes have been recorded species, 'Aranege Suecica?,' p. 184. (' Quarterly Journal of Science,' ^^ Dr. H. H. van Zouteveen, in 1868, July, p. 429) ; but I have his Dutch translation of this work not seen the original accounts. (vol. i. p. 444), has collected several 2^ Kirby and Speuce, ' Introduc- cases 13 2/4 The Descent of Man. Part II. to be described in the next chapter, we may feel almost sure that the stridulation serves, as Westring also believes, to call or to excite the female ; and this is the first case known to me in the ascending scale of the animal kingdom of sounds emitted for this purpose.^" Class, Myriaj;oda. — In neither of the two orders in this class, the millipedes and centipedes, can I find any well-marked instances of such sexual differences as more particularly concern us. In Glomeris li.mhata, however, and perhaps in some few other species, the males differ slightly in colour from the females ; but this Glomeris is a highly variable species. In the males of the Diplopoda, the legs belonging either to one of the anterior or of the posterior segments of the body are modified into pre- hensile hooks which serve to secure the female. In some species of lulus the tarsi of the male are furnished with membranous suckers for the same purpose. As we shall see when we treat of Insects, it is a much more unusual circumstance, that it is the female in Lithobius, which is furnished with prehensile appendages at the extremity of her body for holding the male.^^ CHAPTER X. Secondary Sexual Characters of Insects. Diversified structures possessed by the males for seizing the females — Differences between the sexes, of which the meaning is not understood — Difference in size between the sexes — Thysanura — Diptera — Hemiptera — Homoptera, musical powers possessed by the males alone — Orthoptera, musical instruments of the males, much diversified in structure ; pugnacity ; colours — Neuroptera, sexual differences in colour — Hyme- noptera, pugnacity and colours — Coleoptera, colours ; furnished with great horns, apparently as an ornament ; battles ; stridulating organs generally common to both sexes. In the immense class of insects the sexes sometimes differ in their locomotive-organs, and often in their sense-organs, as in the pectinated and beautifully plumose antennae of the males of many species. In Chloeon, one of the EjDhemerse, the male has great pillared eyes, of which the female is entirely destitute.* The ocelli are absent in the females of certain insects, as in the 2^ Hilgendorf, however, has lately ' Hist. Nat. des Insectes : Apteres,' called attention to an analogous torn. iv. 1847, pp. 17, 19, (58. structure in some of the higher * Sir J. Lubbock, ' Transact, crustaceans, which seems adapted Linnean Soc' vol. xxv. 1866, p. to produce sound ; see ' Zoological 484. With respect to the Mu- Record,' 1869, p. 603. tillidae see West wood, ' Modern ^^ Walckenaer et P. Gervais, Class, of Insects,' vol. ii. p. 213. Chap. X. Insects. 275 Mutillidie ; and here the females are hkewise wingless. But we are chiefly concerned with structures by which one male is enabled to conquer another, either in battle or courtship, through his strength, pugnacity, ornaments, or music. The innumerable contrivances, therefore, by which the male is able to seize the female, may be briefly passed over. Besides the complex structures at the apex of the abdomen, which ought perhaps to be ranked as primary organs,^ " it is astonishing," as Mr. B. D. Walsh ^ has remarked, " how many different organs are worked in by nature " for the seemingly insignificant object of enabling the male to " grasp the female firmly." The mandibles or jaws are some- times used for this purpose; thus the male Corydalis cornutus (a neuropierous insect in some degree allied to the Dragon-flies, &c.) lias immense curved jaws, many times longer than those of the female ; and they are smooth instead of being toothed, so that he is thus enabled to seize her without injury.'^ One of the stag-beetles of North America {Lucanus ela/Juis) uses his jaws, which are much larger than those of the female, for the same purpose, but probably likewise for fighting. In one of the sand-wasps {Ammophild) the jaws in the two sexes are closely alike, but are used for widely different purposes : the males, as Professor Westwood observes, " are exceedingly ardent, seizing " their partners round the neck with their sickle-shaped jaws;"^ whilst the females use these organs for burrowing in sand-banks and making their nests. The tarsi of the front-legs are dilated in many male beetles, or are furnished with broad cushions of hairs ; and in many genera of water-beetles they are armed with a round flat sucker, so that the male may adhere to the slippery body of the female. It is a "^ These organs in the male often species having been observed in differ in closely-allied species, and union. Mr. MacLachlan informs afford excellent specific characters. me (vide ' Stett. Eut. Zeitung,' But their importance, from a func- 1867, s, 155) that when several tional point of view, as Mr. R. species of Phryganidje, which ])re- MacLachlan has remarked to me, sent strongly-pronounced differences has probably been overrated. It of this kind, were confined together has been suggested, that slight dif- by Dr. Aug. Meyer, theji coupled, ferences in these organs would and one pair produced fertile ova. suffice to prevent the intercrossing ^ t -pj^g Practical Entomologist,' _ of well-marked varieties or incipient Philadelphia, vol. ii. May, 1807, species, and would thus aid in their p. 88. development. That this can hardly '' Mr. Walsh, ibid. p. 107. be the case, we may infer from the ^ ' Modern classification of In- many recorded cases (see, for in- sects,' vol. ii. 1840, pp. 205, 206. instance, Bronn, ' Geschichte der Mr. Walsh, who called my attention Natur,' B. ii. 18-13, s. 164; and to the double use of the jaws, says Westwood, ' Transact. Ent. Soc' that he has repeatedly observed vol. iii. 1842, p. 195) of distinct this fact. 2/6 The Descent of Man. Part II. much more unusual circumstance that the female of some water- beetles (Dytiscus) have their elytra deeply grooved, and in Acilius sulcatus thickly set with hairs, as an aid to the male. The females of some other water- beetles (Hydroporus) have their elytra punctured for the same purpose." In the male of Crahro cribrurius (fig. 9), it is the tibia which is dilated into a broad horny plate, with minute mem- braneous dots, giving to it a sin- gular appearance like that of a riddle.'' In the male of Penthe (a genus of beetles) a few of the middle joints of the antennae are dilated and furnished on the in- ferior surface with cushions of hair, exactly like those on the tarsi of the Carabidse, " and obviously for " the same end." In male dragon- flies, " the appendages at the tip " of the tail are modified in an " almost infinite variety of curious " patterns to enable them to em- ^''- 'm^ai:!TowS^Sgure,fYEL"'"^ " brace the neck of the female." Lastly, in the males of many in- sects, the legs are furnished with peculiar spines, knobs or spurs ; or the whole leg is bowed or thickened, but this is by no means invariably a sexual character ; or one pair, or all three IDairs are elongated, sometimes to an extravagant length.^ The sexes of many species in all the orders present differences, of which the meaning is not understood. One curious case is that of a beetle (fig. 10), the male of which has the left mandible much enlarged; so that the mouth is greatly distorted. In another Carabidous beetle, Eurygnathus,^ we have the case. ^ We have here a curious and inexplicable case of dimorphism, for some of the females of four Euro- pean species of Dytiscus, and of cei'tain species of Hydroporus, have their elytra smooth ; and no inter- mediate gradations between the sulcated or punctured, and the quite smooth elytra have been observed. See Dr. 11. Schaum, as quoted in the 'Zoologist,' vol. A-.-vi. 1847-48, p. 1896. Also Kirby and Spence, ' Introduction to Entomology,' vol. iii. 1826, p. 305. ^ Westwood, ' Modern Class.' vol. ii. p. 193. The following state- ment about Penthe, and others in inverted commas, are taken from Mr. Walsh, ' Practical Entomolo- gist,' Philadelphia, vol. ii. p. 88. ^ Kirby and Spence, 'Introduct.' &c., vol. iii. pp. 332-336. ^ ' Insecta Madcrensia,' 1854, p. 20. Chap. X. Insects. 277 unique as ftir as known to Mr. Wollaston, of the head of the female being much broader and larger, though in a variable degree, than that of the male. Any number of such cases could be given. They abound in the Lepidoptera: one of the most extra- ordinary is that certain male butterflies have their fore-legs more or less atrojiliied, with the tibise and tarsi reduced to mere ru- dimentary knobs. The wings, also, in the two sexes often differ in neuration,^*' and some- times considerably in outline, as in the Ari- coris epitiis, wiiicli was shewn to me in the British Museum by Mr. A. Butler. The males of certain South American butterflies have tufts of hair on the margins of the wings, and horny excrescences on the discs of the posterior pair.^^ In several British butter- flies, as shewn by Mr. Wonfor, the males alone are in parts clothed with peculiar scales. The use of the bright light 'of the female glow-worm has been subject to much discus- sion. The male is feebly luminous, as are the larva3 and even the eggs. It has been sup- posed by some authors that the light serves to frighten away enemies,- and by others to guide the male to the female. At last, Mr. Belt ^2 appears to have solved the difficulty : he finds that all the Lampyridse which he has tried are highly distasteful to insectivorous mammals and birds. Hence it is in accordance with Mr. Bates'" view, hereafter to be explained, that many insects mimic the Lampyridae closely, in order to be mistaken for them, and thus to escape destruction. He further be- lieves that the luminous species profit by being at once recognised as unpalatable. It is i^robable that the same explanation may be extended to the '^^ E. Doubleday, ' Annals and 74. Mr. Wonfor's observations are Mag. of Xat. Hist.' vol. i. 1848, p. quoted in ' Popular Science Review,* 379. I may add that the wings in 1868, p. 343. ^- 'The Naturalist in Nicaragua,' 1874, pp. 316-320. On the phos- phorescence of the eggs, see 'Annals and Mag. of Nat. Hist.' 1871,' Nov., p. 372. Fig. 10. Taphroderes distortus (much en- larged). Upper fig- ure, male ; lower figure, female. certain Hymenoptera (see Shuclvard, ' Fossorial Hynienop.' 1837, pp. 39- 43) differ in neuration according to sex. " H. W. Bates, in 'Journal of Proc. Linn. Soc' vol. vi. 1862, p. 2/8 The Descent of Man, Part 11. Elaters, both sexes of which are highly luminous. It is not known why the wings of the female glow-worm have not been developed ; but in her present state she closely resembles a larva, and as larvae are so largely preyed on by many animals, we can understand why she has been rendered so much more luminous and conspicuous than the male ; and why the larvae themselves are likewise luminous. Difference in Size hetween the Sexes. — "With insects of all kinds the males are commonly smaller than the females; and this difference can often be detected even in the larval state. So considerable is the difference between the male and female cocoons of the silk-moth (Bomhyx mori), that in France they are separated by a particular mode of weighing.^^ In the lower classes of the animal kingdom, the greater size of the females seems generally to depend on their developing an enormous number of ova ; and this may to a certain extent hold good with insects. But Dr. Wallace has suggested a much more probable explanation. He finds, after carefully attending to the develop- ment of the caterpillars of Bombyx cynthia and yamamai, and especially to that of some dwarfed caterjDillars reared from a second brood on unnatural food, " that in proportion as the in- " dividual moth is finer, so is the time required for its metamor- " pilosis longer ; and for this reason the female, which is the " larger and heavier insect, from having to carry her numerous " eggs, will be preceded by the male, which is smaller and has " less to mature," ^^ Now as most insects are short-lived, and as they are exposed to many dangers, it would manifestly be ad- vantageous to the female to be impregnated as soon as possible. This end would be gained by the males being first matured in large numbers ready for the advent of the females ; and this again would naturally follow, as Mr A. E. "Wallace has re- marked,^^ through natural selection; for the smaller males would be first matured, and thus would procreate a large number of offspring which would inherit the reduced size of then* male parents, whilst the larger males from being matured later would leave fewer offspring. There are, however, exceptions to the rule of male insects being smaller than the females : and some of these exceptions are intelligible. Size and strength would be an advantage to the males, which fight for the jDossession of the females ; and in those cases, as with the stag-beetle (Lucanus), the males are larger than the females. There are, however, other beetles " Robinet, 'Vers a Soie,' 1848, vol. y. p. 486. p. 207. '5 i Journal of Proc. Ent. Soc. ^^ 'Transact. Ent. Soc' 3rd series, Feb. 4th, 1867, p. Ixxi. Chap. X. TJiysanura. 279 which are not known to fight together, of which the males exceed the females in size ; and the meaning of this fact is not known ; but in some of these cases, as with the huge Dynastes and Megasoma, we can at least see that there would be no necessity for the males to be smaller than the females, in order to be matured before them, for these beetles are not short-lived, and there would be ample time for the pairing of the sexes. So again, male dragon-flies (Libellulidse) are sometimes sensibly larger, and never smaller, than the females;^*' and as Mr. MacLachlan believes, they do not generally pair with the females until a week or fortnight has elapsed, and until they have assumed their proper masculine colours. But the most curious case, shewing on what comj^lex and easily-overlooked relatioDS, so trifling a character as difference in size between the sexes may depend, is that of the aculeate Hymenoptera ; for Mr. F. Smith informs me that throughout nearly the whole of this large group, the males, in accordance with the general rule, are smaller than the females, and emerge about a week before them ; but amongst the Bees, the males oi Aipis melUfica, Anthidium manicatum, and Anthopliora ac&rvorum, and amongst the Fossores, the males of the Methoca ichneumonides, are larger than the females. The explanation of this anomaly is that a marriage flight is absolutely necessary with these species, and the male requires great strength and size in order to carry the female through the air. Increased size has here been acquired in op- position to the usual relation between size and the period of development, for the males, though larger, emerge before the smaller females. We will now review the several Orders, selecting such facts as more particularly concern us. The Lepidoptera (Butterflies and Moths) will be retained for a separate chapter. Order, Thysanura. — The members of this lowly organized order are wingless, dull-coloured, minute insects, with ugly, almost misshapen heads and bodies. Their sexes do not difi"er ; but they are interesting as shewing us that the males pay sedulous court to the females even low down in the animal scale. Sir J. Lubbock ^^ says : " it is very amusing to see these " little creatures (SmyntJmrus luteus) coquetting together. The " male, which is much smaller than the female, runs round her, " and they butt one another, standing face to face, and moving '® For this and other statements see p. 344, on the size of the sexes, see Kirby ^' ' Transact. Linnean Soc' vol. and Spence, ibid. vol. iii. p. 300 ; xxvi, 1868, p. 296. on the dui'ation of life in insects, 28o The Descent of Man. Part II. " backward and forward like tw'o playful lambs. Then the " female pretends to run away and the male runs after her with " a queer appearance of anger, gets in front and stands facing " her again ; then she turns coyly round, but he, quicker and " more active, scuttles round too, and seems to whip her " with his antennae ; then for a bit they stand face to face, " play with their antennae, and seem to be all in all to one " another." Order, Dlptera (Flies). — The sexes differ little in colour. The greatest difference, known to Mr. F. Walker, is in the genus Bibio, in which the males are blackish or quite black, and the females obscure brownish-orange. The genus Elaphomyia, dis- covered by Mr. Wallace ^^ in New Guinea, is highly remarkable, as the males are furnished with horns, of which the females are quite destitute. The horns spring from beneath the eyes, and curiously resemble those of a stag, being either branched or pal- mated. In one of the species, they equal the whole body in length. They might be thought to be adapted for fighting, but as in one species they are of a beautiful pink colour, edged with black, with a pale central stripe, and as these insects have altogether a very elegant appearance, it is perhaps more probable that they serve as ornaments. That the males of some Diptera fight together is certain ; for Prof. Westw^ood ^^ has several times seen this with the Tipulse. The males of other Diptera ap- parently try to win the females by their music : H. Miiller ^ watched for some time two males of an Eristalis courting a female; they hovered above her, and flew from side to side, making a high humming noise at the same time. Gnats and mosquitoes (Culicidse; also seem to attract each other by hum- ming ; and Prof. Mayer has recently ascertained that the hairs on the antennae of the male vibrate in unison with the notes of a tuning-fork, within the range of the sounds emitted by the female. The longer hairs vibrate sympathetically with the graver notes, and the shorter hairs with the higher ones. Landois also asserts that he has repeatedly drawn down a whole swarm of gnats by uttering a particular note. It may be added that the mental faculties of the Diptera are probably higher than in most other in- sects, in accordance with their highly developed nervous system.^^ ^* * The Malay Archipelago,' vol. ^i ggg ^ly^ -^ f. Lowne's interest- ii. 1869, p. 313. ing work, ' On the Anatomy of the '^ 'Modern Classification of In- Blow-fly, Musca vomitoria,' 1870, p. sects,' A'ol. ii. 1840, p. 526. 14. He remarks (p. 33) that, " the 2" Anwendung, &c., ' Verh. d. n. " captured flies utter a peculiar V. Jahrg.' xxix. p. 80. Mayer, in " plaintive note, and that this sound 'American Naturalist,' 1874, p. 236. " causes other flies to disappear." Chap. X. Hemiptera and Homoptera, 281 Order, Hemiptera (Field-Bugs).— Mr. J. W. Douglas, who has particularly attended to the British species, has kindly given me an account of their sexual differences. The males of some species are furnished with wings, whilst the females are wingless ; the sexes differ in the form of their bodies, elytra, antenn£e and tarsi ; but as the signification of these differences are unknown, they may be here passed over. The females are generally larger and more robust than the males. With British, and, as far as Mr. Douglas knows, with exotic species, the sexes do not commonly differ much in colour; but in about six British species the male is considerably darker than the female, and in about four other species the female is darker than the male. Both sexes of some species are beautifully coloured; and as these insects emit an extremely nauseous odour, their con- spicuous colours may serve as a signal that they are unpalat- able to insectivorous animals. In some few cases their colours appear to be directly protective : thus Prof. Hoffmann informs me that he could hardly distinguish a small pink and green species from the buds on the trunks of lime-trees, which this insect frequents. Some species of Eeduvidae make a stridulating noise; and, in the case of Pirates stridulus, this is said ^^ to be effected by the movement of the neck within the pro-thoracic cavity. Accord- ing to Westring, Beduvius jiersonatus also stridulates. But I have no reason to suppose that this is a sexual character, ex- cepting that with non-social insects there seems to be no use for sound-producing organs, unless it be as a sexual call. Order, Homoptera. — Every one who has wandered in a tropi- cal forest must have been astonished at the din made by the male Cicadae. The females are mute; as the Grecian poet Xenarchus says, " Happy the Cicadas live, since they all have *' voiceless waives." The noise thus made could be plainly heard on board the " Beagle," when anchored at a quarter of a mile from the shore of Brazil ;• and Captain Hancock says it can be heard at the distance of a mile. The Greeks formerly kept, and the Chinese now keep these insects in cages for the sake of their song, so that it must be pleasing to the ears of some men.^^ The Cicadidse usually sing during the day, whilst the FulgoridsB appear to be night-songsters. The sound, according to Landois,^* " Westwood, 'Modern Class, of also, on the Fulgorida?, Kirby and Insects,' vol. ii. p. 473. Spence, ' Introduct.' vol. ii. p. 401. "^ These particulars are taken ^4 < Zeitschrift fiir wissenschaft. from Westwood's ' Modern Class, of Zoolog.' B. xvii. 1867, s. 152-158. Insects,' vol. ii. 1840, p. 422. See, 282 The Descent of Man. Part II. is produced by the vibration ot the lips of the spiracles, which are set into motion by a current of air emitted from the trachese ; but tills view has lately been disputed. Dr. Powell appears to have proved 2^ that it is produced by the vibration of a mem- brane, set into action by a speci-al muscle. In the living insect, whilst stridulating, this membrane can be seen to vibrate ; and in the dead insect the proper sound is heard, if the muscle, when a little dried and hardened, is pulled with the point of a pin. In the fem.ale the whole complex musical apparatus is present, but is much less developed than in the male, and is never used for producing sound. With respect to the object of the music, Dr. Hartman, in speaking of the Cicada septemdecim of the United States, says, ^s " the drums are now (June 6th and 7th, 1851) heard in all " directions. This I believe to be the marital summons from " the males. Standing in thick chestnut sprouts about as high " as my head, where hundreds were around me, I observed the " females coming around the drumming males," Ho adds, " this " season (Aug. 1868) a dwarf pear-tree in my garden produced " about fifty larvsB of Cic. prm7iosa ; and I several times noticed " the females to alight near a male while he was uttering his " clanging notes." Fritz Miiller writes to me from S. Brazil that he has often listened to a musical contest between two or three males of a species with a particularly loud voice, seated at a considerable distance from each other : as soon as one had finished his song, another immediately began, and then another. As there is so much rivalry between the males, it is probable that the females not only find them by their sounds, but that, like female birds, they are excited or allured by the male with the most attractive voice. I have not heard of any well-marked cases of ornamental differences between the sexes of the Homoptera. Mr. Douglas informs me that there are three British species, in which the male is black or marked with black bands, whilst the females are pale-coloured or obscure. Order, Orthoptera (Crickets and Grasshoppers).— The males in the three saltatorial families in this Order are remarkable for their musical powers, namely the Achetidse or crickets, the Locustidse for which there is no equivalent English name, and the Acridiidae or grasshoppers. The stridulation produced by some " 'Transact. New Zealand In- from a 'Journal of the Doings of stitute,' vol. V. 1873, p. 286. Cicada septemdecim ' by Dr. Hart- 2^ I am indebted to Mr. Walsh man. for havmg sent me this extract Chap. X. Orthoptera. 283 of the Locustidse is so loud that it can be heard during tlie night at the distance of a mile ; -" and that made by certain species is not unmusical even to the human ear, so that the Indians on the Amazons keep them in wicker cages. All observers agree tliat the sounds serve either to call or excite the mute females. With respect to the migratory locusts of Russia, Korte has given ^^ an interesting case of selection by the female of a male. The males of this species {Pachytylus miyratorius) whilst coupled with the female stridulate from anger or jealousy, if approached by other males. The house-cricket when surprised at night uses its voice to warn its fellows.-^ In North America the Katy-did {Phity- 2>hyllum coneavum,onQoii\\Q Locustidse) is described^" as mount- ing on the upper branches of a tree, and in the evening beginning " his noisy babble, while rival notes issue from the neighbouring " trees, and the groves resound with the call of Kafydid-she-did " the hve-long night." Mr. Bates, in speaking of the Euro- pean field-cricket (one of the Achetidse), says, " the male has " been observed to jDlace him- " self in the evening at the " entrance of his burrow, and " stridulate until a female ap- " preaches, when the louder " notes are succeeded by a " more subdued tone, whilst " the successful musician ca- " resses with his antennae the " mate he has won."^^ Dr. Scudder was able to excite one of these insects to answer him, by rubbing on a file with a quill.^ In both sexes a re- markable auditory apparatus has been discovered by Von Siebold, situated in the front legs Fig. 11, Gryllus carapestris (from Landois). Right-hand figure, under side of part of a wing-nervure, much magnified, showing the teeth, st. Left-hand figure, upper surface of wing- cover, with the projecting, smooth nervure, r, across which the teeth {st) are scraped. 2^ L. Guilding, 'Transact Linn. See' vol. XV. p. 154. 28 I state this on the authority of Koppen, ' Ueber die Heuschrecken in Siidrussland,' 1866, p. 32, for I have in vain endeavoured to procure Korte's work. 29 Gilbert White, 'Nat. Hist, of Selborne,' vol. ii. 1825, p. 262. ^" Harris, ' Insects of New Eng- land/ 1842, p. 128. 31 'The Naturalist on the Ama- zons,' vol. i. 1863, p. 252. Mr. Bates gives a very interesting dis- cussion on the gfadations in the musical apparatus of the three families. See also Westwood, * Modern Class.' vol. ii. pp. 445 and 453. 32 'Proc. Boston Soc. of Nat. Hist.' vol. xi. April, 1868. 33 ' Nouveau Manuel d'Anat. Comp.' (French translat.), torn. i. 1850, p. 567. 284 The Descent of Man. Part II. In the three ramilies the sounds are differently produced. In the males of the Achetidse both wing-covers have the same apparatus ; and this in the field-cricket {Gryllus campestris, fig. 11) consists, as described by Landois,^* of from 131 to 138 sharp, transverse ridges or teeth (.s^) on the under side of one of the nervures of the wing-cover. This toothed nervure is rapidly scraped across a projecting, smooth, hard ner- vure (r) on the upper surface of the opposite wing. First one wing is rubbed over the other, and then the movement is reversed. Both wings are raised a little at the same time, so as to increase the resonance. In some species the wing-covers of the males are furnished at the base with a talc-like plate.^^ I here give a drawing (fig. Vl) of the teeth on the under side of the nervure of another Fig. 12. Teeth of Ner- spccics of Grvllus, viz., (J. domesticus. With SrcS^SoS)!' 'respect to the formation of these teeth. Dr. Gruber has shewn ^*^ that they have been de- veloped by the aid of selection, from the minute scales and hairs with which the wings and body are covered, and I came to the same conclusion with respect to those of the Coleoptera. But Dr. Gruber further shews that their development is in part directly due to the stimulus from the friction of one wing over the other. In the Locustidse the opposite wing-covers differ from each other in structure (fig. 13), and the action caonot, as in the last family, be reversed. The left wing, which acts as the bow, lies over the right wing which serves as the fiddle. One of the nervures (a) on the under surface of the former is finely serrated, and is scraped across the prominent nervures on tlie upper surface of the opposite or right wing. In our British fhasgonura viridissima it appeared to me that the serrated nervure is rubbed against the rounded hind-corner of the opposite wing, the edge of which is thickened, coloured brown, and very sharp. In the right wing, but not in the left, there is a little plate, as transparent as talc, surrounded by nervures, and called the speculum. In Epliiiiinger vitium, a member of this same family, we have a curious subordinate modification ; for the wing-covers are greatly reduced in size, but " the posterior part of the pro-thorax is elevated into a kind ^* ' Zeitschi-ift fiir wissenschaft. ^^ ' Ueber der Tonapparat der Zoolocf.' B. xvii. 1867, s. 117. Locustiden, ein Beitrag zum Dar- ^^ Westwood, ' Modern Class, of wiaismus,' ' Zeitsch. fiir wissensch. Insects,' vol. i. p. 440. Zoolog.' B. xxii. 1872, p. 100. Chap. X. Orthoptera, 285 "of dome over tlie wing-covers, and which hxis probably the " effect of increasing the sound." '^'^ Fig. 13. ChloroccElus Tanana (from Bates), a, b. Lobes ux" opposite wing-covers. We thus see that the musical apparatus is more differentiated or specialised in the Locustidse (which include, I believe, the most powerful performers in the Order), than in the Achetidre, in which both wing-covers have the same structure and the same function.'^ Landois, however, detected in one of the Locustidae, namely in Decticus, a short and narrow row of small teeth, mere rudiments, on the inferior surface of the right wing- cover, which underlies the other and is never used as tlje bow. I observed the same rudimentary structure on the under side of the right wing-cover in Phasyonura viridissima. Hence we may infer with confidence that the Ijocustidsa are descended from a form, in which, as in the existing Achetidse, both wing-covers had serrated nervures on the under surface, and could be indifferently used as the bow ; but tliat in the Locustidse the two wing-covers gradually became differentiated and perfected. 2' Westwood, 'Modern Class, of Insects,' vol. i. p. 453. ^^ Landois, 'Zeitsch. f. wiss. Zoolog.' B. xvii. 1867, s. 121, 122. 286 The Descent of Man, Part II. on the principle of the division of labour, the one to act ex- clusively as the bow, and the other as the fiddle. Dr. Gruber takes the same view, and has shewn that rudimentary teeth are commonly found on the inferior surface of the right wing. By what steps the more simple apparatus in the Achetidse originated, we do not know, but it is probable that the basal portions of the wing-covers originally overlapped each other as they do at present; and that the friction of the nervures produced a gTating sound, as is now the case with the wing-covers of tlie females.^^ A grating sound thus occasionally and accidentally made by the males, if it served them ever so little as a love-call to the females, might readily have been intensified through sexual selection, by variations in the roughness of the nervures having been continually preserved. In the last and third Family, namely the Acridiidse or grasshoppers, the stridulation is produced in a very different manner, and according to Dr. Scudder, is not so shrill as in the prec.eding Families. The inner surface of the femur (fig. 14, r) is furnished with a longitudinal row of minute, elegant, lancet- shaped, elastic teeth, from 85 to 93 in number ;^*' and these are scraped across the sharp, projecting nervures on the wing-covers, which are thus made to vibrate and resound. Karris'*^ says _ that when one of the males begins to play, he first " bends " the shank of the hind-leg " beneath the thigh, where it " is lodged in a furrow de- " signed to receive it, and ** then draws the leg briskly " up and down. He does not " play both fiddles together, " but alternately, first upon " one and then on the other." In many species, the base of the abdomen is hollowed out into a great cavity which is believed to act as a re- sounding board. In Pneu- mora (fig. 15), a S. African same family, we meet with a new Fig. 14. Hind-leg of Stenobothrus pratorum : r, the stridulating ridge ; lower figure, the teeth forming the ridge, much magnified (from Landois). genus belonging to the 39 Mr. Walsh also informs me that he has noticed that the female of the Platyphyllum concavum, *' when captured makes a feeble "grating noise by shuffling her " wing-covers together." *" Landois, ibid. s. 113. *i ' Insects of New England, 1842, p. 133. Chap. X. Orthoptera, 2^7 and remarkable modification; in the males a small notched ridge projects obliquely from each side of the abdomen, against which the hind femora are rubbed.^^ As the male is furnished with wings (the female being wingless), it is re- markable that the thighs are not rubbed in tlie usual manner against the "wing-covers ; but this may perhaps be accounted for by the unusually small size of the hind-legs. I have not been able to examine the inner surface of the thighs, which, judging Fig. 15. Pneumora (from specimens in the British Museum). Upper figure, male; lower figure, female. from analogy, would be finely serrated. The species of Pneumora have been more profoundly modified for the sake of stridulation than any other orthopterous insect ; for in the male the whole body has been converted into a musical instrument, being *• Westwood, ' Mode] u Classification,' vol. i. p. 462. 288 The Descent of Man. Part II. distended witli air, like a great pellucid bladder, so as to increase the resonance. Mr. Trimen informs me that at the Cape of Good Hope these insects make a wonderful noise during the night. In the three foregoing families, the females are almost always destitute of an efficient musical apparatus. But there are a few exceptions to this rule, for Dr. Gruber has shewn that both sexes of Eplujypiger vitium are thus provided; though the organs differ in the male and female to a certain extent. Hence we cannot suppose that they have been transferred from the male to the female, as appears to have been the case with the secondary sexual characters of many other animals. They must have been independently developed in the two sexes, which no doubt mutually call to each other during the season of love. In most other Locustidse (but not according to Landois in Decticus) the females have rudiments of the stridulatory organs proper to the male; from whom it is probable that these have been transferred. Landois also found such rudiments on the under surface of the wing-covers of the female Achetidse, and on the femora of the female Acridiidte. In the Homoptera, also, the females have the proper musical apparatus in a functionless state ; and we shall hereafter meet in other divisions of the animal kingdom with many instances of structures proper to the male being present in a rudimentary condition in the female. Landois has observed another important fact, namely, that in the females of the Acridiidte, the stridulating teeth on the femora remain throughout life in the same condition in which they first appear during the larval state in both sexes. In the males, on the other hand, they become further developed, and acquire their perfect structure at the last moult, when the insect is mature and ready to breed. From the facts now given, we see that the means by which the males of the Orthoptera produce their sounds are extremely diversified, and are altogether different from those employed by the Homoptera.^^ But throughout the animal kingdom we often find the same object gained by the most diversified means ; this seems due to the whole organisation having undergone mul- tifarious changes in the course of ages, and as part after part varied different variations were taken advantage of for the same general purpose. The diversity of means for producing sound in the three families of the Orthoj^tera and in the *^ Landois has recently found in moptera ; and this is a surprising certain Orthoptera rudimentary fact. See ' Zeitschr. fiir wissensch. structures closely similar to the Zoolog.' B. xxii. Heft 3, 1871, p. sound-producing organs in the Ho- 348. Chap. X.- Or t hop t era. 289 Bomoptera, impresses the mind with the high importance of these structures to the males, for the sake of calling or alluring the females. We need feel no surprise at the amount of modification which the Orthoptera have undergone in this respect, as we now know, from Dr. Scudder's remarkable discovery/* that there has been more than ample time. This naturalist has lately found a fossil insect in the Devonian formation of New Brunswick, which is furnished with " the well-known tympanum or stridu- " lating apparatus of the male Locustidse." The insect, though in most respects related to the Neuroptera, appears, as is so often the case with very ancient forms, to connect the two related Orders of the Neuroptera and Orthoptera. I have but little more to say on the Orthoptera. Some of the species are very pugnacious: when two male field-crickets (GryUus camjoestris) are confined together, they fight till one kills the other; and the species of Mantis are described as mancBuvriug with their sword-like front-limbs, like hussars with their sabres. The Chinese keep these insects in little bamboo cages, and match them like game-cocks.'*^ With respect to colour, some exotic locusts are beautifully ornamented ; the posterior wings being marked with red, blue, and black ; but as throughout the Order the sexes rarely differ much in colour, it is not probable that they owe their bright tints to sexual selection. Conspicuous colours may be of nse to these insects, by giving notice that they are unpalatable. Thus it has been observed ^° that a bright-coloured Indian locust was invariably rejected when offered to birds and lizards. Some cases, however, are known of sexual differences in colour in this Order. The male of an American cricket-*^ is described as being as white as ivory, whilst the female varies from almost white to greenish- yellow or dusky. Mr. Walsh informs me that the adult male of Spectrum femoratum (one of the Phasmidse) " is of a shining " brownish-yellow colour ; the adult female being of a dull, " opaque, cinereous brown ; the young of both sexes being green." Lastly, I may mention that the male of one curious kind of cricket*^ is furnished with "a long membranous appendage, " which falls over the face like a veil ;" but what its use may be, is not known. ** ' Transact. Ent. Soc' 3r J series, *^ The CEcantlms nivalis. Harris, vol. ii. ('Journal of Proceedings,' 'Insects of New England,' 1842, p.. p. 117.) " 124. The two sexes of (E. pcllucichts ' *^ Westwood, ' Modern Class, of of Europe differ, as I hear from Insects,' vol. i. p. 427 ; for crickets, Victor Carus, in nearly the same p. 445. manner. *^ Mr. Ch. Home, in ' Proc. Ent. ** Platyblemnus : Westwood, Soc ' May 3, 1869, p. xii. ' Modern Class.' vol. i. p. 447. 2QO The Descent of Man. Part II. Order, Neuroj)tera. — Little need here be said, except as to colour. In the Ephemeridse the sexes often differ slightly in their obscure tints ; *^ but it is not probable that the males are thus rendered attractive to the females. The Ijibellulidae, or dragon-flies, are ornamented with sjDlendid green, blue, yellow, and vermilion metallic tints ; and the sexes often differ. Thus. as Prof. Westwood remarks,^" the males of some of the Agrionidae, " are of a rich blue with black wings, whilst the '* females are fine green with colourless wings." But in Agrion Bamhurii these colours are exactly reversed in the two sexes.^^ In the extensive N. American genus of Hetserina, the males alone have a beautiful carmine spot at the base of each wing. In Anax Junius the basal part of the abdomen in the male is a vivid ultramarine blue, and in the female grass-green. In the allied genus Gomphus, on the other hand, and in some other genera, the sexes differ but little in colour. In closely-allied forms throughout the animal kingdom, similar cases of the sexes differing greatly, or very little, or not at all, are of frequent occurrence. Although there is so wide a difference in colour between the sexes of many Libellulidse, it is often difficult to say which is the more brilliant ; and the ordinary coloration of the two sexes is reversed, as we have just seen, in one species of Agrion. It is not probable that their colours in any case have been gained as a protection. Mr. MacLachlan, who has closely attended to this family, writes to me that dragon-flies— the •tyi-ants of the insect-world — are the least liable of any insect to be attacked by birds or other enemies, and he believes that their bright colours serve as a sexual attraction. Certain dragon-flies apparently are attracted by particular colours : Mr. Patterson observed ^^ that the Agrionidrs, of which the males are blue, settled in numbers on the blue float of a fishing line ; whilst two other species were attracted by shining white colours. It is an interesting fact, first noticed by Schelver, that, in several genem belonging to two sub-families, the males on first emergence from the pupal state, are coloured exactly like the females; but that their bodies in a short time assume a con- spicuous milky-blue tint, owing to the exudation of a kind of oil, soluble in ether and alcohol. Mr. MacLachlan believes that in the male of Lihelkda depressa this change of colour does not occur until nearly a fortnight after the metamorphosis, when the sexes are ready to pair. *^ B. D. Walsh, the ' Pseudo-neu- indebted to this naturalist for the roptera of Illinois,' in ' Proc. Ent. following facts on Hetarina, Anax, Soc. of Philadelphia,' 1862, p, 361. and Gomphus. 5* 'Modern Class.' vol. ii. p. 37. ^- 'Transact. Ent. Soc' vol. i. " Walsh, ibid. p. 381. I am 1836, p. Ixxxi. CiiAP. X. HynieiiGptera. 291 Certain si3ecies of Neurotliemis present, according to Brauer, °^ a curious case of dimorphism, some of the females having ordinary wings, whilst others have them " very richly netted, as in the " males of the same species." Brauer " exjilains the phenomenon " on Darwinian principles by the suj^position that the close " netting of the veins is a secondary sexual character in the " males, which has been abruptly transferred to some of the " females, instead of, as generally occurs, to all of them." Mr. MacLachlan informs me of another instance of dimorphism in several species of Agrion, in which some individuals are of an orange colour, and these are invariably females. This is probably a case of reversion ; for in the true Libellulse, when the sexes differ in colour, the females are orange or yellow; so that supposing Agrion to be descended from some primordial form which resembled the typical Libellulse in its sexual cha- racters, it would not be surprising that a tendency to vary in this manner should occur in the females alone. Although many dragon-flies are large, powerful, and fierce insects, the males have not been observed by Mr. MacLachlan to fight together, excepting, as he believes, in some of the smaller sj^ecies of Agrion. In another group in this Order, namely, the Termites or white ants, both sexes at the time of swarming may be seen running about, " the male after the female, sometimes " two chasing one female, and contending with great eagerness " who shall win the prize."^^ The Atropos pulsatorius is said to make a noise with its jaws, which is answered by other individuals.^^ Order, Hymenoptera. — That inimitable observer, M. Fabre,^" in describing the habits of Cerceris, a wasp-like insect, remarks that " fights frequently ensue between the males for the possession of " some particular female, who sits an apparently unconcerned " beholder of the struggle for supremacy, and when the victory " is decided, quietly flies away in company with the conqueror." Westwood ^' says that the males of one of the saw-flies (Tenthre- dinse) " have been found fighting together, with their mandibles " locked." As M. Fabre speaks of the males of Cerceris striving to obtain a particular female, it may be well to bear in mind that insects belonging to this Order have the power of recognising ^' See abstract in the ' Zoological ^^ See an interesting article. Record' for 1867, p. 450. 'The Writings of Fabre,' in 'Nat. ^■* Kirby and Spence, 'Introduct. Hist. Review,' April 1862, p. 122. to Entomology,' vol. ii. 1818, p. 35. ^' 'Journal of Proc. of Entoraolog. " Houzeau, ' Les Facultes Men- Soc' Sept, 7th, 1863, p. 169. tales,' &c. Tom. 1. p. 104. 292 The Descent of Man. Fart II. each other after long intervals of time, and are deeply attached. For instance, Pierre Hnber, whose accuracy no one doubts, separated some ants, and when, after an interval of four months, they met others which had formerly belonged to the same- community, they recognised and caressed one another with their antennae. Had they been strangers they would have fought together. Again, when two communities engage in a battle, the ants on the same side sometimes attack each other in tlie general confusion, but they soon perceive their mistake, and the one ant soothes tbe other.^^ In this Order slight differences in colour, according to sex, are common, but conspicuous differences are rare except in the family of Bees ; yet both sexes of certain groups are so brilliantly coloured— for instance in Chrysis, in which vermilion and metallic greens prevail — that we are tempted to attribute the result to sexual selection. In the Ichneumonids^, according to Mr. Walsli,^^ the males are almost universally lighter-coloured than the females. On the other hand, in the Tenthredinidse the males are generally darker than the females. In the Siricidse the sexes frequently differ ; thus the male of Sirex juvencus is banded with orange, whilst the female is dark purple ; but it is difficult to say which sex is the more ornamented. In Tremex cohnnhop. the female is much brighter-coloured than the male. I am informed by Mr. F. Smith, that the male ants of several species are black, the females being testaceous. In the family of Bees, especially in the solitary species, as I hear from the same entomologist, the sexes often differ in colour. The males are generally the brighter, and in Bombus as well as in Apathus, much more variable in colour than the females. In Anthophora return the male is of a rich fulvous-brown, whilst the female is quite black : so are the females of several species of Xylocopa, the males being bright yellow. On the other hand the females of some species, as of Andrcena fiilva, are much brighter-coloured than the males. Such differences in colour' can hardly be accounted for by the males being defenceless and thus requiring protection, whilst the females are well defended by their stings. H. Miiller, *^° who has particularly attended to the habits of bees, attributes these differences in colour in chief part to sexual selection. That bees have a keen perception of colour is certain. He says that the males search eagerly and fight for the possession of the females ; and he accounts thi'ough 58 p. Huber, ' Recherches sur les Philadelphia,' 1866, pp. 238-239. Moeurs des Fourmis,' 1810, pp. 150, ^^ ' Anwendung der Darwinschen 165. Lehi-e auf Bienen.' Verh. d. li. ^^ ' Proc. Entomolog. Soc. of Jahrg. xxix. Chap. X. Hyniienoptera. 293 such contests for the mandibles of the males being in certain species larger than tliose of the females. In some cases tlie males are far more numerous than the females, either early in the season, or at all times and places, or locally ; whereas the females in other cases are apparently in excess. In some species the more beautiful males appear to have been selected by the females ; and in others the more beautiful females by the males. Consequently in certain genera (Miiller, p. 42), the males of the several species differ much in appearance, vs^hilst the females are almost indistinguishable; in other genera the reverse occurs. H. Miiller believes (p. 82) that the colours gained by one sex through sexual selection have often. been transferred in a variable degree to the other sex, just as the pollen-collecting apparatus of the female has often been transferred to the male, to whom it is absolutely useless.''^ Mutilla Earopxa makes a stridulating noise ; and according to Goureau ^'^ both sexes have this power. He attributes the sound to the friction of the third and preceding abdominal segments, and I find that these surfaces are marked with very fine con- centric ridges ; but so is the projecting thoracic collar, into which the head articulates, and this collar, when scratched with the point of a needle, emits the proper sound. It is rather surprising that both sexes should have the power of stridulating, as the male is winged and the female wingless. It is notorious that Bees express certain emotions, as of anger, by the tone of their humming; and according to H. Miiller (p. 80), the males of some species make a peculiar singing noise whilst pursuing the females. ®^ M. Perrier in his article 'la Se- male grandfathers? To take a case lection sexuelled'aprfes Darwin '('Re- with ordinary animals as nearly vue Scientitiqiae,' Feb. 1873, p. 868), parallel as possible: if a female of without apparently having reflected any white quadruped or bird were much on the subject, objects that as crossed by a male of a black breed, the males of social bees are known and the male and female offspring to be produced from unfertilised were paired together, will it be ova, they could not transmit new pretended that the grandchildren characters to their male offspring. would not inherit a tendency to This is an extraordinary objection, blackness from their male grand- A female bee fertilised by a male, father? The acquirement of new which presented some character fa- characters by the sterile worker-bees cilitating the union of the sexes, or is a much more difficult case, but I rendering him more attractive to have endeavoured to show in my the female, would lay eggs which ' Origin of Species,' how these sterile would produce only females ; but beings are subjected to the power of these young females would next natural selection, year produce males ; and will it be ^^ Quoted by Westwood, ' Modern pretended that such males would- Class, of Insects,' vol. ii. p. 214-. not inherit the characters of their 294 The Descent of Man. Part II. Order, Coleoj)tera (Beetles). — Many beetles are coloured so as to resemble the surfaces which they habitually frequent, and they thus escape detection by their enemies. Other species, for instance diamond-beetles, are ornamented with siDlendid colours, which are often arranged in stripes, spots, crosses, and other elegant patterns. Such colours can hardly serve directly as a protection, except in the case of certain flower-feeding species ; but they may serve as a warning or means of recognition, on the same principle as the phosphorescence of the glow-worm. As with beetles the colours of the two sexes are generally alike, we have no evidence that they have been gained through sexual selection; but this is at least possible, for they may have been developed in one sex and then transferred to the other ; and this view is even in some degree probable in those groups which possess other well-marked secondary sexual characters. Blind beetles, which cannot of course behold each other's beauty, never, as I hear from Mr. Waterhouse, jun., exhibit bright colours, though they often have polished coats ; but the expla- nation of their obscurity may be that they generally inhabit caves and other obscure stations. Some Longicorns, especially certain Prionidse, offer an excep- tion to the rule that the sexes of beetles do not differ in colour. Most of these insects are large and splendidly coloured. The males in the genus Pyrodes,*^^ which I saw in Mr. Bates's col- lection, are generally redder but rather duller than the females, the latter being coloured of a more or less splendid golden-green. On the other hand, in one species the male is golden-green, the female being richly tinted with red and purple. In the genus Esmeralda the sexes differ so greatly in colour that they have been ranked as distinct species ; in one species both are of a beautiful shining green, but the male has a red thorax. On the whole, as far as I could judge, the females of those Prionidse, in "^ Pyrodes pulcherrimus, in the family of Longicorns. Messrs. which the sexes differ conspicuously, R. Trimen and Waterhouse, jun., has been described by Mr. Bates in inform me of two Lamellicorns, 'Transact. Ent. Soc' 1869, p. 50. viz., a Peritrichia and Trichius, the I will specify the few other cases in male of the latter being more which 1 have heard of a difference obscurely coloured than the female. m colour between the sexes of In Tillus elongatus the male is black, beetles. Kirby and Spence (' In- and the female always, as it is troduct. to Entomology,' vol. iii. p. believed, of a dark blue colour, with 301) mention a Cantharis, Meloc, a red thorax. The male, also, of Rhagium, and the Leptura testacca ; Orsodacna atra, as I hear from Mr. the male of the latter being tes- Walsh, is black, the female (the taceous, with a black thorax, and so-called 0. ruficollis) having .a the female of a dull red all over, rufous thorax. The.se two latter beetles belong to Chap. X. Coleoptera. 295 which the sexes differ, are coloured more richly than the males, and 'this does not accord with the common rule in regard to colour, when acquired through sexual selection. A most remarkable distinction between the sexes of many beetles is presented by the great horns which rise from the head, thorax, and clypeus of the males ; and in some few cases from the under surface of the body. These horns, in the great family of the Lamellicorns, resemble those of various quadrupeds, such as stags, rhinoceroses, &c., an-d are wonderful both from their size and diversified shapes. Instead of describing them, I have given figures of the males and females of some of the more re- markable forms. (Figs. 16 to 20.) The females generally ex- liibit rudiments of the horns in the form of small knobs or ridges ; but some are destitute of even the slightest rudiment. On the other hand, the horns are nearly as well developed in the female as in the male of Phanceus lancifer ; and only a little less well developed in the females of some other species of this genus and of Copris. I am informed by Mr. Bates that the horns do not differ in any manner corresponding with the more important characteristic differences between the several subdivisions of the family : thus within the same section of the genus Onthophagus, there are species which have a single horn, and others which have two. Fig. 16. Chalcosoma atlas. Upper figure, male (roduced) ; lower figure, female (nat. size). 296 'The Descent of Man. Part II. Copris isidis. (Left-hand figures, males.) Plianaeus faunus. Fisr. 19 ripelicus cantoii. Fig. 20. Onthophagiis rangifer, enlarged Chap. X. ' Coleoptera. ' 297 In almost all cases, the horns are remarkable from their ex- cessive variability; so that a graduated series can be formed, from the most highly developed males to others so degenerate that they can barely bo distinguished from the females. Mr. Walsh ^^ found that in Phcuueus caniifex the horns were thrice as long in some males as in others. Mr. Bates, after examining above a hundred males of Ontliophagus runcjifer (fig. 20), thought that he had at last discovered a species in which the horns did not vary ; but further research proved the contrary. The extraordinary size of the horns, and their widely different structure in closely-allied forms, indicate that they have been formed for some purpose ; but their excessive variability in the males of the same species leads to the inference that this purpose cannot be of a definite nature. The horns do not show marks of friction, as if used for any ordinary work. Some authors sup- pose "^^ that as the males wander about much more than the females, they require horns as a defence against tJieir enemies ; but as the horns are often blunt, they do not seem well adapted for defence. The most obvious conjecture is that they are used by the males for fighting together ; but the males have never been observed to fight; nor could Mr. Bates, after a careful examination of numerous species, find any sufficient evidence, in their mutilated or broken condition, of their having been thus used. If the males had been habitual fighters, the size of their bodies would probably have been increased through sexual selection, so as to have exceeded that of the females; but Mr. Bates, after comparing the two sexes in above a hundred species of the Copridse, did not find any marked difference in this respect amongst well-developed individuals. In Lethrus, moreover, a beetle belonging to the same great division of the Lamellicorns, the males are known to fi^'ht, but are not provided with horns, though their mandibles are much larger than those of the female. The conclusion that the horns have been acquired as ornaments is that which best agrees with the fact of their having been so immensely, yet not fixedly, developed, — as shewn by their extreme variability in the same species, and by their extreme diversity in closely- allied species. This view will at first appear extremely improbable; but we shall hereafter find with many animals standing much higher in the scale, namely fishes, amphibians, reptiles and birds, that various kinds of crests, knobs, horns and combs have been developed apparently for this sole purpose. The males of Onitls furciftr (fig. 21), and of some other ^■* ' Pi-oc. Entomolog. Soc. of ^^ Kirby and Spence, ' latroduct. rhiladelphia,' 1864, p. 228. Entomolog.' vol. iii. p. 300. 14 298 ^he Descent of Man. Part II. species of tlie genus, are furnished with singular projections on their anterior femora, and with a great fork or pair of horns on the lower surface of the thorax. Judging from other insects, these may aid the male in clinging to the female. Although the males have not even a trace of a horn on the upper surface of the body, yet the fe- males plainly exhibit a rudiment of a single horn on the head (fig. 22, a), and of a crest (&) on the thorax. That the slight thoracic crest in the female is a rudiment of a pro- jection proper to the male, though entirely absent in the male of this jDarticular species, is clear : for the female of Buhas bison (a genus which comes next to Onitis) has a similar slight crest on the thorax, and the male bears a great projection in the same situation. So, again, there can hardly be a doubt that the little point (a) on the head of the female Onitis Fig 21. Onitis furcifer, male viewed from be- neath. Fig. 22. Left-hand fignre, male of Onitis furcifer, viewed laterally. Right-hand figure, female, a. Rudiment of cephalic horn. b. Truce of thoracic horn or crest. furcifer, as well as on the head of the females of two or three allied species, is a rudimentary representative of the cephalic horn, which is common to the males of so many Lameilicorn beetles, as in Phanseus (fig. 18). The old belief that rudiments have been created to complete the scheme of nature is here so far from holding good, that we have a complete inversion of the ordinary state of things in the family. We may reasonably suspect that the males originally bore horns and transferred them to the females in a rudimentary condition, as in so many othej* Lamellicorns. Why the males subsequently lost their horns, we know not ; but this may have been caused through the principle of compensation, owing to the development of the large horns and projections on the lower surface ; and as these are confined to the males, the rudiments of the upper horns on the females would not have been thus obliterated. Chap. X. Coleoptera, 299 The cases hitherto given refer to the Lamellicorns, but the males of some few other beetles, belonging to two widely distinct groups, namely, the Cui'culionidre and Staphylinidce, are fur- nished with homs — in the former on the lower surface of the body,*"^ in the latter on the upi^er surface of the head and thorax. In the Staphylinid?e, the horns of the males are extraordinarily variable in the same species, just as we have seen with the Lamellicorns. In Siagonium we have a case of dimorphism, for the males can be divided into two sets, differing greatly in tiie size of their bodies and in the development of their horns, without intermediate gradations. In a species of Bledius (fig. 23), also belonging to the Staphylinidse, Professor Westwood Fig. 23. Bledius taurus, magnified. Left-hand figure, male ; right-hand figure female. states that, "male specimens can be found in the same locality " in which the central horn of the thorax is very large, but the " horns of the head quite rudimental ; and others, in which the "thoracic horn is much shorter, whilst the protuberances on " the head are long." *^^ Here we apparently have a case of compensation, which throws light on that just given of the supposed loss of the upper horns by the males of Onitis. Law of Battle. — Some male beetles, which seem ill-fitted .for fighting, nevertheless engage in conflicts for the possession of the females. Mr. Wallace *^^ saw two males of Leptorhynchus angustatus, a linear beetle with a much elongated rostrum, " fighting for a female, who stood close by busy at her boring. " They pushed at each other with their rostra, and clawed and " thumped, apparently in the greatest rage." The smaller male, however, " soon ran away, acknowledging himself vanquished." In some few cases male beetles are well adapted for fighting, by possessing great toothed mandibles, much larger than those of the females. This is the case with the common stag-beetle {Lucanus cervus), the males of which emerge from the pupal state about a week before the other sex, so that several may often be seen pursuing the same female. At this season they ®® Kirby and Spence, ' Introduct. gonium in an intermediate condi- Entomolog.' vol. iii. p. 329. tion, .so that the dimorphism is not ®^ ' Modern Classification of In- strict, sects,' vol. i. p. 172: Siagonium, ^^ 'The Malay Archijjelago,' vol. p. 172. In the British Museum I ii. 1869, p. 276. Riley, Sixth "* Report noticed one male specimen of Sia- on insects of Missouri/ 1874, p. 115. 300 The Descent of Mmi. Part II. engage in fierce conflicts. When Mr. A. H. Davis *^^ enclosed two males with one female in a box, the larger male severely I.)inched the smaller one, until he resigned his pretensions. A friend informs me that when a boy he often iDut the males together to see them fight, and he noticed that they were much bolder and fiercer than the females, as with the higher animals. The males would seize hold of his finger, if held in front of them, but not so the females, although they have stronger jaws. The males of many of the Lucanidse, as well as of the above-mentioned Leptorhynchus, are larger and more powerful insects than the females. The two sexes of Lethnis cepJialotes (one of the Lamellicorns) inhabit the same burrow; and the male has larger mandibles than the female. If, during the breeding-season, a strange male attempts to enter the burrow, he is attacked ; the female does not remain passive, but closes the mouth of the burrow, and encourages her mate by con- tinually pushing him on from behind ; and the battle lasts until the aggressor is killed or runs away. '** The two sexes of another Lamellicorn beetle, the Ateuchus cicafricosus, live in pairs, and seem much attached to each other ; the male excites the female to roll the balls of dung in which the ova are deposited ; and if she is removed, he becomes much agitated. If the male is removed the female ceases all work, and as M. Brulerie '^^ believes, would remain on the same spot until she died. The great mandibles of the male Lucanidse are extremely variable both in size and structure, and in this respect resemble the horns on the head and thorax of many male Lamellicorns and Staphylinidse. A perfect series can be formed from the best-provided to the worst-provided or degenerate males. Al- though the mandibles of the common stag-beetle, and probably of many other species, are used as efficient weapons for fighting, it is doubtful whether their great size can thus be accounted for. We have seen that they are used by the Lucanus elaphus of N. America for seizing the female. As they are so con- spicuous and so elegantly branched, and as owing to their great length they are not well adapted for pinching, the suspicion has crossed my mind that they may in addition serve as an ornament, like the horns on the head and thorax of the various species above described. The male Chiaf^ognathus Grant ii of S. Chile — a splendid beetle belonging to the same family — has ^^ 'Entomological Magazine,' vol. ""^ Quoted from Fischer, in '•Diet, i. 1833, p. 82. See also on the Class. d'Hist. Nat.' torn. x. p. 324. conflicts of this species, Kirby and ^> ' Ann. Soc. Entomolog. France,' Spence, ibid. vol. iii. p. 314 ; and 1866, as quoted in ' Journal of Westwood, ibid. vol. i. p. 187. Travel,' by A. Murray, 1868, p. 135. Chap. :^. Coleoptera. 301 enormously developed mandibles (fig. '24) ; he is bold and pug- nacious ; when threatened he faces round, opens his great jaws, and at the same time stridulates loudly. But the mandibles were not strong enough to pinch my finger so as to cause actual pain. Sexual selection, which implies the possession of considerable perceptive powers and of strong passions, seems to have been more effective with the Lamellicorns than with any other family of beetles. With some species the males are provided with weapons for fighting; some live in pairs and show mutual affection ; many have the power of stridulating when excited ; many are furnished with the most ex- traordinary horns, apparently for the sake of ornament; and some, which are diurnal in their habits, are gor- geously coloured. Lastly, several of the largest beetles in the world belong to this family, which was placed by Linnseus and Fabricius at the head of the Order.^^ Stridulating organs. — Beetles belong- ing to many and widely distinct families possess these organs. The sound thus produced can sometimes be heard at the distance of several feet or even yards,'^^ but it is not comparable with that made by the Orthoptera. The rasp generally consists of a narrow, slightly-raised surface, crossed by very fine, parallel ribs, sometimes so fine as to cause iridescent colours, and having a very elegant appearance under the microscope. In some cases, as Avith Typhosus, minute, bristly or scale-like prominences, with which the whole surrounding surface is covered in approximately parallel lines, could be traced passing into the ribs of the rasp. The Fi°r. 24. Chiasognathus grantii, reduced. U ppcr figure, male ; lower figure, female. ^^ Westwood, vol. i. p. 184. Modern Class.' " Wollaston, ' On certain Musical Curculionidaj,' 'Annals and Mag. of Nat. Hist.' vol. vi. 18G0, p. 14. 302 The Descent of Man. Part II. transition takes place by their becoming confluent and straight, and at the same time more prominent and smooth. A hard ridge on an adjoining part of the body serves as the scraper for the rasp, but this scraper in some cases has been specially modified for the purpose. It is rapidly moved across the rasp, or conversely the rasp across the scraper. Fig. 25. Necrophorus (from Landois). r. The two rasps, the rasp highly magnified. Left-hand figure, part of These organs are situated in widely different positions. In the carrion-beetles (Necrophorus) two parallel rasps (r, fig. 25) stand on the dorsal surface of the fifth abdominal segment, each rasp^* consisting of 126 to 140 fine ribs. These ribs are scraped against the posterior margins of the elytra, a small portion of which projects beyond the general outline. In many Crioceridas, and in Clylhra ^-punctata (one of the Chrysomehdse), and in some Tenebrionidse, &c.,'^^ the rasp is seated on the dorsal apex of the abdomen, on the pygidium or pro-pygidium, and is scraped in the same manner by the elytra. In Heterocerus, which belongs to another family, the rasps are placed on the sides of the first abdominal segment, and are scraped by ridges on the femora.'^^ In certain Curculionidse and Carabidae,''^ the parts ^^ Landois, ' Zeitschrift fiir wiss. Zoolog.' B. xvii. 1867, s. 127. ^^ I am greatly indebted to Mr. G. R. Crotch for having sent me man}^ prepared specimens of various beetles belonging to these three families and to others, as well as for valuable information. He believes that the power of stridulation in the Clythra has not been previously- observed. I am also much indebted to Mr. E. W. Janson, for informa- tion and specimens. I may add that my son, Mr. F. Darwin, finds that Dermestes murinus stridulates, but he searched in vain for the apparatus. Scolytus has lately been described by Dr. Chapman as a stridulator, in the 'Entomolo- gist's Monthly Magazine,' vol. vi. p. 130. '^ Schiodte, translated in * Annals and Mag. of Nat. Hist.' vol. xx. 1867, p. 37. ^^ Westringhas described (Krover, ' Naturhist. Tidskrift,' B. ii. 1848- 49, p. 334) the stridulating organs in these two, as well as in other families. In the Carabidae I have examined Elaphrus uliginosus and Blethisa multipiinctata, sent to me by Mr. Crotch. In Blethisa the transverse ridges on the furrowed border of the abdominal segment do Chap. X. Coleoptera. 303 are completely reversed in position, for the rasps are seated on the inferior surface of the elytra, near their apices, or along their outer margins, and the edges of the abdominal segments serve as the scrapers. In Pelohius Ileriminni (one of Dytiscidje or water-beetles) a strong ridge runs parallel and near to the sutural margin of the elytra, and is crossed by ribs, coarse in the middle part, but becoming gradually finer at both ends, especially at the upper end; when this insect is held under water or in the air, a stridulating noise is produced by the extreme horny margin of the abdomen being scraped against the rasps. In a great number of long-horned beetles (Longi- cornia) the organs are situated quite otherwise, the rasp being on the meso-thorax, which is rubbed against the pro-thorax; Landois counted 238 very fine ribs on the rasp of Ceramhyx heros. Many Lamellicorns have the power of stridulating, and the organs differ greatly in position. Some species stridulate very loudly, so that when Mr. F. Smith caught a Trox sahidosus, a gamekeeper, who stood by, thought he had caught a mouse ; but I failed to discover the proper organs in ^ this beetle. In Geotrupes and Typhoeus a narrow ridge runs obliquely across (r, fig. 2G) the coxa of each hind-leg (having in G. ster- corarius 84 ribs), which is scraped by a specially projecting part of one of the ab- dominal segments. In the nearly allied Copris lunaris, an excessively narrow fine rasp runs along the sutural margin of the elytra, with another short rasp near the basal outer mar- gin; but in some other Coprini the rasp is seated, according to Leconte,'^^ on the dorsal surface of the abdomen. In Oryctes it is seated on the pro-pygidium ; and, according to the same entomologist, in some other Dynastini, on the under surface of the elytra. Lastly, Westring states that in Omaloplia hrunnea the rasp is placed on the pro-sternum, and the scraper on the meta-sternum, the parts thus occupying the under surface of the body, instead of the upper surface as in the Longicorns. We thus see that in the different coleopterous families the not, as far as I could judge, come of Illinois, for having sent me ex- into play in scraping the rasps on tracts from Leconte's ' Introduction the elytra. to Entomology,' pp. 101, 143. " 1 am indebted to Mr. Walsh, ip. 26. Hind-leg of Gp(jtrnpcs storcora- rius (from Landois). , Rasp. c. Coxa. /. Femur, t. Tibia tr. Tarsi. 304 The Descent of Man. Paet II. stridulating organs are wonderfully diversified in position, but not much in structure. Within the same family some species are provided with these organs, and others are destitute of them. This diversity is intelligible, if we suppose that originally various beetles made a shuffiing or hissing noise by the rubbing together of any hard and rough parts of their bodies, which happened to be in contact ; and that from the noise thus produced being in some way useful, the rough surfaces were gradually developed into regular stridulating organs. Some beetles as they move, now produce, either intentionally or unintentionally, a shuffling noise, without possessing any proper organs for the purpose. Mr. Wallace infoims me that the Euchirus longimanus (a Lamellicorn, with the anterior legs wonderfully elongated in the male) " makes, whilst moving, a low hissing sound by the pro- '* trusion and contraction of the abdomen ; and when seized it " produces a grating sound by rubbing its hind-legs against the " edges of the elytra." The hissing sound is clearly due to a narrow rasp running along the sutural margin of each elytron ; and I could likewise make the grating sound by rubbing the shagreened surface of the femur against the granulated margin of the corresponding elytron ; but I could not here detect any proper rasp ; nor is it hkely that I could have overlooked it in so large an insect. After examining Cychrus, and reading what Westring has written about this beetle, it seems very doubtful whether it possesses any true rasp, though it has the power of emitting a sound. From the analogy of the Orthoptera and Homoptera, I expected to find the stridulating organs in the Coleoptera differing according to sex; but Landois, who has carefully examined several sjDecies, observed no such difference ; nor did Westring; nor did Mr. G. E. Crotch in preparing the many specimens which he had the kindness to send me. Any difference in these organs, if slight, would, however, be difficult to detect, on account of their great variability. Thus, in the first pair of specimens of Necrophorus humafor and of Pelohius which I ex- amined, the rasp was considerably larger in the male than in the female; but not so with succeeding specimens. In Geo- triipes stercorarius the rasp appeared to me thicker, opaquer, and more prominent in three males than in the same number of females; in order, therefore, to discover whether the sexes differed in their power of stridulating, my soa, Mr. F. Darwin, collected fifty-seven living specimens, which he separated into two lots, according as they made a greater or lesser noise, when held in the same manner. He then examined all these specimens, and found that the males were very nearly in the same proportion Chap. X. Coleoptera. 305 to the females in both the lots. Mr. F. Smith has kept alive inimerous specimens of Monoijnclms pseudacoH (Cnrculiomda}), and is convinced that both sexes stridulate, and apparently in an equal degree. . , . ^ ^ Nevertheless, the power of stridulating is certainly a sexual character in some few Coleoptera. Mr. Crotch discovered that the males alone of two species of Heliopathes (TenebrionidsB) possess stridulating organs. I examined live males of 11. (jlhhiis, and in all these there was a well-developed rasp, partially divided into two, on the dorsal suriace of the terminal abdominal •sef'-ment ; whilst in the same number of females there was not even a rudiment of the rasp, the membrane of this segment being transparent, and much thinner than in the male. In H cribratostriatus the male has a similar rasp, excepting that it is not partially divided into two portions, and the female is completely destitute of this organ; the male in addition has on the apical margins of the elytra, on each side of the suture, three or four short longitudinal ridges, which are crossed by extremely fine ribs, parallel to and resembling those on the abdominal rasp; whether these ridges serve as an independent rasp, or as a scraper for the abdominal rasp, I could not decide: the female exhibits no trace of this latter structure. Ao-ain, in three species of the Lamellicorn genus Oryctes, we have a nearly parallel case. In the females of 0. gryphus and nasicornis the ribs on the rasp of the pro-pygidmm are less continuous and less distinct than in the males; but the chief difference is that the whole upper surface of this segment, when held in the proper light, is seen to be clothed with hairs, which are absent or are represented by excessively fine down m the males. It should be noticed that in all Coleoptera the effective part of the rasp is destitute of hairs. In 0. senegalensts the difference between the sexes is more strongly marked, and this is best seen when the proper abdominal segment is cleaned and viewed as a transparent object. In the female the whole surface is covered with little separate crests, bearing spines ; whilst m the male these crests in proceeding towards the apex, become more and more confluent, regular, and naked; so that three- fourths of the segment is covered with extremely fine parallel ribs which are quite absent in the female. In the females, however, of all three species of Oryctes, a slight grating or Gtridulating sound is produced, when the abdomen of a softened .specimen is pushed backwards and forwards. In the case of the Heliopathes and Oryctes there can hardly be a doubt that the males stridulate in order to call or to excite the females; but with most beetles the stridulation 306 The Desceftt of Man. Pakt II. apparently serves both sexes as a mntual call. Beetles striclu- late under various emotions, in the same manner as birds use their voices for many purposes besides singing to their mates. The great Chiasognathus stridulates in anger or defiance ; many species do the same from distress or fear, if held so that they cannot escape; by striking the hollow stems of trees in the Canary Islands, Messrs. Wollaston and Crotch were able to discover the presence of beetles belonging to the genus Acalles by their stridulation. Lastly, the male Ateuchus stridulates to encourage the female in her work, and from distress when she is removed.'^^ Some naturalists believe that beetles make this noise to frighten away their enemies ; but I cannot think that a quadruped or bird, able to devour a large beetle, would be frightened by so slight a sound. The belief that the stridu- lation serves as a sexual call is supported by the fact that death- ticks {Anohium tessellatuni) are well known to answer each other's ticking, and, as I have myself observed, a tapping noise artificially made. Mr. Doubleday also informs me that he has sometimes observed a female ticking,^" and in an hour or two afterwards has found her united with a male, and on one occasion surrounded by several males. Finally, it is probable that the two sexes of many kinds of beetles were at first enabled to find each other by the slight shuffling noise produced by the rubbing together of the adjoining hard parts of their bodies; and that as those males or females which made the greatest noise succeeded best in finding partners, rugosities on various parts of their bodies were gradually developed by means of sexual selection into true stridulating organs. ^® M. P. de la Brulerie, as quoted Landois, ' Zeitschrift fiir wissen. in 'Journal of Travel,' A. Murray, Zoolog.' B. xvii. s. 131. Oliver vol. i. 1868, p. 135. says (as quoted by Kirby and '" According to Mr. Doubleday, Spence, ' Introduct.' vol. ii. p. 395) " the noise is produced by ihe in- that the female of Pimelia striata " sect raising itself on its legs as produces a rather loud sound by " high as it can, and then striking striking her abdomen against any " its thorax five or six times, in hard substance, " and that the male, *' rapid succession, against the sub- " obedient to this call, soon attends " stance upon which it is sitting." " her, and they pair." For references on this subject see Chap. XI. Biitterjiies and Moths. 307 CHAPTER XI. Insects, continued. — Order Lepidoptera. (butterflies and moths.) Courtship of butterflies— Battles — Ticking noise— Colours conimon to both feexes, or more brilliant in the males — Examples — Not due to the direct action of the conditions of life — Colours adapted for protection — Colours of moths— Display — Perceptive powers of the Lepidoptera — Variability — Causes of the difference in colour between the males and females— Mimicry, female butterflies more brilliantly coloured than the males — Bright colours of caterpillars — Summary and concluding remarks on the secondary sexual characters of insects — Birds and insects compared. In this great Order the most interesting points for us are the differences in colour between the sexes of the same species, and between the distinct species of the same genus. Nearly the whole of the following chapter will be devoted to this subject ; but I will first make a few remarks on one or two other points. Several males may often be seen pursuing and crowding round the same female. Their courtship appears to be a prolonged affair, for I have frequently watched one or more males pirouet- ting round a female until I was tired, without seeing the end of the courtship. Mr. A. G. Butler also informs me that he has several times watched a male courting a female for a full quarter of an hour ; but she pertinaciously refused bim, and at last settled on the ground and closed her wings, so as to escape from his addresses. Although butterflies are weak and fragile creatures, they are pugnacious, and an Emperor butterfly ^ has been captured with the tips of its wings broken from a conflict with another male. Mr. Collingwood, in speaking of the frequent battles between the butterflies of Borneo, says, " They whirl round each other with " the greatest rapidity, and appear to be incited by the greatest " ferocity." The Ageronia feronia makes a noise like that produced by a toothed wheel passing under a spring catch, and which can be heard at the distance of several yards : I noticed this sound at Eio de Janeiro, only when two of these butterflies were chasing each other in an irregular course, so that it is probably made during the courtship of the sexes.^ 1 Apatura Iris: 'The Entomolo- Natura-list,' 18G8, p. IS.'), gist's Weekly Intelligence,' 1859, p. ^ gee my 'Journal of Researches,' 139. For the Bornean Butterflies, 1845, p. 33. Mr. Doubleday has 6e« C. Collingwood, ' Rambles of a detected (' Proc. Ent. See' March 3o8 The Descent of Man. Part II. Some moths also produce sounds ; for instance, the males of Thecophora fovea. On two occasions Mr. F. Buchanan White ^ heard a sharp quick noise made by the male of Hylophila jjrasinana, and which he believes to be produced, as in Cicada, by an elastic membrane, furnished with a muscle. He quotes, also, Guenee, that Setina produces a sound like the ticking of a watch, apparently by the aid of " two large tympaniform " vesicles, situated in the pectoral region ; " and these " are much " more developed in the male than in the female." Hence the sound-producing organs in the Lepidoptera appear to stand in some relation with the sexual functions. I have not alluded to the well-known noise made by the Death's Head Sphinx, for it is generally heard soon after the moth has emerged from its cocoon. Girard has always observed that the musky odour, which is emitted by two species of Sphinx moths, is peculiar to the males ;^ and in the higher classes we shall meet with many instances of the males alone being odoriferous. Every one must have admired the extreme beauty of many butterflies and of some moths ; and it may be asked, are their colours and diversified patterns the result of the direct action of the i)hysical conditions to which these insects have been exposed, without any benefit being thus derived ? Or have successive variations been accumulated and determined as a protection, or for some unknown purpose, or that one sex may be at- tractive to the other ? And, again, what is the meaning of the colours being widely different in the males and females of certain siDccies, and alike in the two sexes of other species of the same genus ? Before attempting to answer these questions a body of facts must be given. With our beautiful English butterflies, the admiral, peacock, and painted lady (Vanessse), as well as many others, the sexes are alike. This is also the case with the magniflcent Heliconidae, and most of the Danaidse in the tropics. But in certain other tropical groups, and in some of our English butterflies, as the purple emperor, orange-tip, &c. {Apatura Iris and Anthocharis cardamines), the sexes differ either greatly or slightly in colour. No language suffices to describe the splendour of the males of 3rd, 1845, p. 123) a peculiar mem- observations, * The Scottish Natural- branous sac at the base of the ist,* July 1872, p. 214. front wings, which is probably con- ^ ' The Scottish Naturalist,' July nected with the production of the 1872, p. 213. sound. For the case of Thecophora, * ' Zoological Record,' 1869, p. see 'Zoological Record,' 1869, p. 347. 401. For Mr. Buchanan White's Chap. XL Butterflies and Moths. 309 some tropical species. Even within the same genus Ave often find species presenting extraordinary differences between the sexes, whilst others have their sexes closely alike. Thns in the South American genus Epicalia, Mr. Bates, to whom I am indebted for most of the following facts, and for looking over this whole discussion, informs me that he knows twelve species, the two sexes of which haunt the same stations (and this is not always the case with butterflies), and which, therefore, cannot have been differently affected by external conditions.^ In nine of these twelve species the males rank amongst tlie most brilliant of all butterflies, and differ so greatly from the comparatively plain females that they were formerly placed in distinct genera. The females of these nine species resemble each other in their general type of coloration; and they likewise resemble both sexes of the species in several alhed genera, found in various parts of the world. Hence we may infer that these nine species, and probably all the others of the genus, are descended from an ancestral form which was coloured in nearly the same manner. In the tenth species the female still retains the same general colouring, but the male resembles her, so that he is coloured in a much less gaudy and contrasted manner than the males of the previous species. In the eleventh and twelfth species, the females depart from the usual type, for they are gaily decorated almost like the males, but in a somewhat less degree. Hence in these two latter species the bright colours of the males seem to have been transferred to the females ; whilst in the tenth species the male has either retained or recovered the plain colours of the female, as well as of the parent-form of the genus. The sexes in these three cases have thus been rendered nearly alike, though in an opposite manner. In the allied genus Eubagis, both sexes of some of the species are plain-coloured and nearly alike ; whilst with the greater number the males are decorated with beautiful metallic tints in a diversified manner, and differ much from their females. The females throughout the genus retain the same general style of colouring, so that they resemble one another much more closely than they resemble their own males. In the genus Papilio, all the species of the ^neas group are remarkable for their conspicuous and strongly contrasted colours, and they illustrate the frequent tendency to gradation in the amount of difference between the sexes. In a few species, for instance in P. ascauius, the males and females are alike ; in * See also Mr. Bates's paper in the same subject, in regard to ♦ Proc. Ent. Soc. of Philadelphia,' Diadema, in ' transact. Entomolog. 1865, p. 206. Also Mr. Wallace on Soc. of London,' 1869, p. 278. 3IO The Descent of Mail. Part II. others the males are either a little brighter, or very much more superb than the females. The genus Juuouia, allied to our Vaness?e, offers a nearly parallel case, for although the sexes of most of the species resemble each other, and are destitute of rich colours, yet in certain species, as in J. cenone, the male is rather more bright- coloured than the female, and in a few (for instance J. andremiaja) the male is so different from the female that he might be mistaken for an entirely distinct species. Another striking case was pointed out to me in the British Museum by Mr. A. Butler, namely, one of the tropical American Theclse, in which both sexes are nearly alike and wonderfully splendid ; in another species the male is coloured in a similarly gorgeous manner, whilst the whole upper surface of the female is of a dull uniform brown. Our common little English blue butterflies of the genus Lyc^na, illustrate the various dif- ferences in colour between the sexes, almost as well, though not in so striking a manner, as the above exotic genera. In Lycxna agestis both sexes have wings of a brown colour, bordered with small ocellated orange spots, and are thus alike. In L. csgon the wings of the male are of a fine blue, bordered with black ; whilst those of the female are brown, with a similar border, closely resembling the wings of X. agestis. Lastly, in L. arion both sexes are of a blue colour and are very like, though in the female the edges of the wings are rather duskier, with the black spots plainer ; and in a bright blue Indian sj^ecies both sexes are still more alike. I have given the foregoing details in order to show, in the first place, that when the sexes of butterflies differ, the male as a general rule is the more beautiful, and departs more from the usual type of colouring of the group to which the species belongs. Hence in most groups the females of the several species resemble each other much more closely than do the males. In some cases, however, to which I shall hereafter allude, the females are coloured more splendidly than the males. In the second place, these details have been given to bring clearly before the mind that within the same genus, the two sexes frequently present every gradation from no difference in colour, to so great a difference that it was long before the two were placed by entomologists in the same genus. In the third l^lace, we have seen that when the sexes nearly resemble each other, this appears due either to the male having transferred his colours to the female, or to the male having retained, or perhaps recovered, the jr-rimordial colours of the group. It also deserves notice that in those groups in which the sexes differ, the females usually somewhat resemble the males, so that when Chap. XI. Btittei'Jlies and Aloths. 311 the males cire beautiful to an extraordinary degree, the females almost invariably exhibit some degree of beauty. From the many cases of gradation in the amount of difference between the sexes, and from the prevalence of the same general type of coloration throughout the whole of the same group, we may con- clude that the causes have generally been the same which have determined the brilliant colouring of the males alone of some species, and of both sexes of other species. As so many gorgeous butterflies inhabit the tropics, it has often been supposed that they owe their colours to the great heat and moisture of these zones ; but Mr. Bates ° has shewn by the comparison of various closely-allied groups of insects from the temperate and tropical regions, that this view cannot be maintained ; and the evidence becomes conclusive wlien bril- liantly-coloured males and plain-coloured females of the same species inhabit the same district, feed on the same food, and follow exactly the same habits of life. Even when the sexes resemble each other, we can hardly believe that their brilliant and beautifully-arranged colours are the purposeless result of the nature of the tissues and of the action of the surrounding conditions. With animals of all kinds, whenever colour has been modified for some special purpose, this has been, as far as we can judge, either for direct or indirect protection, or as an attraction between the sexes. With many species of butterflies the upper surfaces of the wings are obscure; and this in all probability leads to their escaping observation and danger. But butterflies would be particularly liable to be attacked by their enemies when at rest ; and most kinds whilst resting raise their wings vertically over their backs, so that the lower surface alone is exposed to view. Hence it is this side which is often coloured so as to imitate the objects on which these insects commonly rest. Dr. Bossier, I believe, first noticed the similarity of the closed wings of certain Vanesste and other butterflies to the bark of trees. Many analogous and striking facts could be given. The most interesting one is that recorded by Mr. Wallace '' of a common Indian and Sumatran butterfly (Kallima), which disappears like magic when it settles on a bush ; for it hides its head and antennae between its closed wings, which, in form, colour and veining, cannot be distinguished from a withered leaf with its footstalk. In some other cases the lower « 'The Naturalist on the Ama- 18G7, p. 10. A woodcut of the zons,' vol. i. 1863, p. 19. Kallima is given by Mr. Wallace in ^ See the interesting article in ' Hardwicke's Science Gossip,' Sept. the ' Westminster Review,* July 18G7, p. 19G. 312 The Descent of Man. Part 11. surfaces of the wings are brilliantly coloured, and yet are protective ; thus in Theda ruhi the Avings when closed are of an emerald green, and resemble the young leaves of the bramble, on which in spring this butterfly may often be seen seated. It is also remarkable that in very many species in which the sexes differ greatly in colour on their upper surface, the lower surface is closely similar or identical in both sexes, and serves as a IDrotection.^ Although the obscure tints both of the up])er and under sides of many butterflies no doubt serve to conceal them, yet we cannot extend this view to the brilliant and conspicuous colours on the upper surface of such species as our admiral and peacock Yanessge, our white cabbage-butterflies (Pieris), or the great swallow-tail Papilio which haunts the open fens — for these butterflies are thus rendered visible to every living creature. In these species both sexes are alike ; but in the common brim- stone butterfly (Gonepteryx rhamni), the male is of an intense yellow, whilst the female is much paler; and in the orange- tip (Anthocharis cardamines) the males alone have their wings tipped with bright orange. Both the males and females in these cases are conspicuous, and it is not credible that their difference in colour should stand in any relation to ordinary protection. Prof. Weismann remarks,^ that the female of one of the Lycsense expands her brown wings when she settles on the ground, and is then almost invisible ; the male, on the other hand, as if aware of the danger incurred from the bright blue of the upper surface of his wings, rests with them closed ; and this shews that the blue colour cannot be in any way protective. Nevertheless, it is probable that conspicuous colours are in- directly beneficial to many species, as a warning that they are unpalatable. For in certain other cases, beauty has been gained through the imitation of other beautiful species, which inhabit the same district and enjoy an immunity from attack by being in some way offensive to their enemies ; but then we have to account for the beauty of the imitated species. As Mr. Walsh has remarked to me, the females of our orange- tip butterfly, above referred to, and of an American species {Anth. genutia) probably shew us the primordial colours of the parent-species of the genus; for both sexes of four or five widely-distributed species are coloured in nearly the same manner. As in several previous cases, we may here infer that it is the males of Anth. cai'damines and genutia which have departed from the usual type of the genus. In the Anth. sara 8 Mr. G. Fraser, in ' Nature,' » ' Einfluss der Isolirung auf die April 1871, p. 489. Artbildung,' 1872, p. 58. Chap. XI. BiUterflies and Moths. 313 from California, the orange-tips to the wings have been partially developed in the female ; but they are paler than in the male, and slightly different in some other respects. In an allied Indian form, the Iphias glaucippe, the orange-tips are fully developed in both sexes. In this Iphias, as pointed out to me by Mr. A. Butler, the under surface of the wings marvellously resembles a pale- coloured leaf; and in our English orange-tip, the under surface resembles the flower-head of the wild parsley, on which the butterfly often rests at night.^*^ The same reason which compels us to believe that the lower surfaces have here been coloured for the sake of protection, leads us to deny that the wings have been tipped with bright orange for the same purpose, especially when this character is confined to the males. Most Moths rest motionless during the whole or gi-eater pai-t of the day with their wiDgs depressed ; and the whole upper surface is often shaded and coloured in an admirable manner, as Mr. Wallace has remarked, for escaping detection. The front- wings of the Bombycidae and Noctuidse,^^ when at rest, generally overlap and conceal the hind- wings ; so that the latter might be brightly coloured without much risk; and they are in fact often thus coloured. During flight, moths would often be able to escape from their enemies ; nevertheless, as the hind-wings are then fully exposed to view, their bright colours must generally have been acquired at some little risk. But the following fact shews how cautious we ought to be in drawing conclusions on this head. The common Yellow Under- wings (Triphsena) often fly about during the day or early evening, and are then conspicuous from the colour of their hind-wings. It would naturally be thought that this would be a source of danger ; but Mr. J. Jenner Weir believes that it actually serves them as a means of escape, for birds strike at these brightly coloured and fragile surfaces, instead of at the body. For in- stance, Mr. Weir turned into his aviary a vigorous specimen of Triphcena pronuba, which was instantly pursued by a robin; but the bird's attention being caught by the coloured wings, the moth was not captured until after about fifty attempts, and small portions of the wings were repeatedly broken off. He tried the same experiment, in the open air, with a swallow and T. fimbria', but the large size of this moth probably interfered with its capture.^^ We are thus reminded of a statement made '0 See the interesting observatious Science Gossip,' Sept. 18G7, p. 193. hy Mr. T. W. Wood, ' The Student,' i^ g^g j^jgo, on this subject, Mr. Sept. 1868, p. 81. Weir's paper in 'Transact. Eut. Soc' •1 Mr. Walhice in ' Hardwicke's 1869, p. 23. 314 The Descent of Man. Part II. by Mr. Wallace,^^ namely, that in the Brazihan forests and Malayan islands, many common and highly-decorated butterflies are weak flyers, though furnished with a broad expanse of wing ; and they " are often captured with pierced and broken wings, " as if they had been seized by birds, from which they had " escaped : if the wings had been much smaller in proportion " to the body, it seems probable that the insect would more " frequently have been struck or pierced in a vital part, and " thus the increased expanse of the wings may have been in- " directly beneficial." Display. — The bright colours of many butterflies and of some moths are specially arranged for display, so that they may be readily seen. During the night colours are not visible, and there can be no doubt that the nocturnal moths, taken as a body, are much less gaily decorated than butterflies, all of which are diurnal in their habits. But the moths of certain families, such as the Zygsenidas, several Sphingidse, Uraniidai some Arctiidse and Saturniidse, fly about during the day or early evening, and many of these are extremely beautiful, being far brighter coloured than the strictly nocturnal kinds. A few exceptional cases, however, of bright-coloured nocturnal species have been recorded.^* There is evidence of another kind in regard to display. Butterflies, as before remarked, elevate their wings when at rest, but whilst basking in the sunshine often alternately raise and depress them, thus exposing both surfaces to full view ; and although the lower surface is often coloured in an obscure manner as a protection, yet in many species it is as highly decorated as the upper surface, and sometimes in a very different manner. In some tropical species the lower surface is even more brilliantly coloured than the upper. ^^ In the Eng- lish fritillaries (Argynnis) the lower surface alone is orna- mented with shining silver. Nevertheless, as a general rule, the upjxir surface, which is probably more fully exposed, is coloured more brightly and diversely than the lower. Hence the lower surface generally affords to entomologists the more 13 < Westminster Review,' July Insects of New England,' 184-2, p. 315. 1867, p. 16. ^^ Such differences between the ^* For instance, Lithosia ; but upper and lower surfoces of the Prof. Westwood (' Modern Class, of wings of several species of Papilio, Insects,' vol. ii. p. 390) seems sur- may be seen in the beautiful plates prised at this case. On the relative to Mr. Wallace's ' Memoir on the colours of diurnal and nocturnal Papilionidae of the Malayan Region," Lepidoptera, see ibid. pp. 333 and in 'Transact. Linn. Soc' vol. xxv. 392; also Harris, 'Treatise on the part i. 1865. Chap. XL Butterflies and Moths. 3 1 5 useful character for detecting the affinities of the various species, Fritz Mliller informs me that three species of Castnia are found near his house in S. Brazil : of two of them the hind- wings are obscure, and are always covered by the front- wings when these butterflies are at rest ; but the. third species has black hind-wings, beautifully spotted with red and white, and these are fully expanded and displayed whenever the butterfly rests. Other such cases could be added. If we now turn to the enormous group of moths, which, as I hear from Mr. Stainton, do not habitually expose the under surface of their wings to full view, we find this side very rarely coloured with a brightness greater than, or even equal to, that of the upper side. Some exceptions to the rule, either real or apparent, must be noticed, as the case of Hypopyra.^^ Mr. Trimen informs me that in Guenee's great work, three moths are figured, in which the under surface is much the more brilliant. For instance, in the Australian Gastrophora the upper surface of the fore-wing is pale greyish-ochreous, while the lower surface is magnificently ornamented by an ocellus of cobalt-blue, placed in the midst of a black mark, surrounded by orange-yellow, and this by bluish-wliite. But the habits of these three moths are unknown ; so that no explanation can be given of their unusual style of colouring. Mr. Trimen also informs me that the lower surface of the wings in certain other Geometrse" and quadrifid Noctuse are either more variegated or more brightly-coloured than the upper surface ; but some of these species have the habit of " holding their wings quite erect " over their backs, retaining them in this position for a con- " siderable time," and thus exposing the under surface to view. Other species, when settled on the ground or herbage, now and then suddenly and slightly lift up their wings. Hence the lower surface of the wings being brighter than the upper surface in certain moths is not so anomalous as it at first appears. The Saturniidae include some of the most beautiful of all moths, their wings being decorated, as in our British Emperor moth, with fine ocelli ; and Mr. T. W. "VVood^* observes that they resemble butterflies in some of their movements; "for " instance, in the gentle waving up and down of the wings as if " for display, which is more characteristic of diurnal tlian of ** nocturnal Lepidoptera." " See Mr. Wormald on this the Geometra}) in 'Transact. Eut. moth : ' Proc. Ent. Soc' March 2nd, Soc' new series, vol. v. pi. xv. and 1868. xvi. 1' See also an account of the S. ^^ ' Proc. Ent. Soc. of London,' American genus Erateina (one of July 6, 18(38, p. xxvii. 3i6 T lie Descent of Man. Part II. It is a singular fact that no British moths which are bril- liantly coloured, and, as far as I can discover, hardly any foreign species, differ much in colour according to sex ; though this is the case with many brilliant butterflies. The male, however, of one American moth, the Saturnia lo, is described as having its fore-wings deep yellow, curiously marked with purplish-red spots ; whilst the wings of the female are purple-brown, marked with grey lines.^^ The British moths which differ sexually in colour are all brown, or of various dull yellow tints, or nearly white. In several species the males are much darker than the females,^*^ and these belong to grouj^s which generally fly about during the afternoon. On the other hand, in many genera, as Mr. Stainton informs me, the males have the hind- wings whiter than those of the female — of which fact Agrotis exdamationis offers a good instance. In the Ghost Moth {Hepialus humuli) the difference is more strongly marked ; the males being white, and the females yellow with darker markings.^^ It is probable that in these cases the males are thus rendered more conspicuous, and more easily seen by the females whilst flying about in the dusk. From the several foregoing facts it is impossible to admit that the brilliant colours of butterflies, and of some few moths, have commonly been acquired for the sake of protection. We have seen that their colours and elegant patterns are arranged and exhibited as if for display. Hence I am led to believe that the females prefer or are most excited by the more brilliant ^^ Harris, ' Treatise,' eing brightly-coloured and thus finding partners, succeeded in leaving more numerous oflfspring. In order to account for the frequent transmission of characters to one sex alone, Mr. Wallace expresses his belief that the more common form of equal inheritance by both sexes can be chan.2:ed through natural selection into inheritance by one sex alone, but in favour of this view I can discover no evidence. We know from what occurs under domestication that new characters often appear, which from the first are transmitted to one sex alone ; and by the selection of such variations there would not be the slightest difficulty in giving bright colours to the males alone, and at the same time or subsequently, dull colours to the females alone. In this manner the females of some butterflies and moths have, it is probable, been rendered inconspicuous for the sake of protection, and widely different from their males. I am, however, unwilling without distinct evidence to admit that two complex processes of selection, each requiring the transference of new characters to one sex alone, have been carried on with a multitude of species, — that the males have been rendered more brilliant by beating their rivals, and the females more dull-coloured by having escaped from their enemies. The male, for instance, of the common brimstone butterfly (Gonepteryx), is of a far more intense yellow than the female, though she is equally conspicuous ; and it does not seetn probable that she specially acquired her pale tints as a protec- tion, though it is probable that the male acquired his bright colours as a sexual attraction. The female of Anthocharis car- damines does not possess the beautiful orange wing-tips of the male; consequently she closely resembles the white butterflies (Pieris) so common in our gardens ; but we have no evidence that this resemblance is beneficial to her. As, on the other hand, she resembles both sexes of several other species of the genus inhabiting various quarters of the world, it is probable that she has simply retained to a large extent her primordial colours. Finally, as we have seen, various considerations lead to the conclusion that with the greater number of brilliantly-coloured Lepidoptera it is the male which has been chiefly modified through sexual selection; the amount of difference between Chap. XT. Btitterjiies and Moths. 323 the sexes mostly depending on tlie form of inheritance which has prevailed. Inheritance is governed by so many unknown laws or conditions, that it seems to us to act in a capricious manner ; ^* and we can thus, to a certain extent, understand how it is that with closely allied species the sexes either differ to an astonishing degree, or are identical in colour. As all the suc- cessive steps in the process of variation are necessarily trans- mitted through the female, a greater or less number of such steps might readily become developed in her; and thus we can understand the frequent gradations from an extreme difference to none at all between the sexes of allied species. These cases of gradation, it may be added, are much too common to favour the supposition that we here see females actually undergoing the ]3rocess of transition and losing their brightness for the sake of protection ; for w^e have every reason to conclude that at any one time the greater number of speci(;s are in a fixed condition. Mimicry. — This principle was first made clear in an admirable paper by Mr. Bates,-^ who thus threw a flood of light on many obscure problems. It had previously been observed that certain butterflies in S, America belonging to quite distinct families, resembled the Heliconidse so closely in every stripe and shade of colour, that they could not be distinguished save by an ex- perienced entomologist. As the Heliconidse are coloured in their usual manner, whilst the others depart from the usual colouring of the groups to which they belong, it is clear that the latter are the imitators, and the Heliconidee the imitated. Mr. Bates further observed that the imitating species are com- paratively rare, whilst the imitated abound, and that the two sets live mingled together. From the fact of the HeliconidsB being conspicuous and beautiful insects, yet so numerous in individuals and species, he concluded that they must be pro- tected from the attacks of enemies by some secretion or odour ; and this conclusion has now been amply confirmed,-*' especially by Mr. Belt. Hence Mr. Bates inferred that the butterflies which imitate the protected species have acquired their present marvellously deceptive appearance through variation and natural selection, in order to be mistaken for the protected kinds, and thus to escape being devoured No explanation is here attempted of the brilliant colours of the imitated, but only of the imitating butterflies. We must account for the colours of the former in the same general manner, as in the cases previously discussed "* ' The Variation of Animals and xxiii. 1802, p. 495. Plants under Domestication,' vol. ii. ^o < Pyoc. Ent. Soc' Dec. 3rd, chap. xii. p. 17. 1866, p. xlv. 29 ' Transact. Linn. Soc' vol. 324 The Descent of Man. Part II. in this chapter. Since the publication of Mr. Bates' paper, similar and equally striking facts have been observed by ]^[r. Wallace in the Malayan region, by Mr, Trimen in South Africa, and by Mr. Eiley in the United States.^^ As some writers have felt much difficulty in understanding how the first steps in the process of mimicry could have been effected through natural selection, it may be well to remark that the process probably commenced long ago between forms not widely dissimilar in colour. In this case even a slight variation would be beneficial, if it rendered the one species more Like the other ; and afterwards the imitated species might be modi- fied to an extreme degree through sexual selection or other means, and if the changes were gradual, the imitators might easily be led along the same track, until they differed to an equally extreme degree from their original condition ; and they would thus ultimately assume an appearance or colouring wholly unlike that of the other members of the group to which they belonged. It should also be remembered that many species of Lepidoptera are liable to considerable and abrupt variations in colour. A few instances have been given in this chapter ; and many more may be found in the papers of Mr. Bates and BIr. Wallace. With several species the sexes are alike, and imitate the two sexes of another species. But Mr. Trimen gives, in the paper already referred to, three cases in which the sexes of the imitated form differ from each other in colour, and the sexes of the imitating form differ in a like manner. Several cases have also been recorded where the females alone imitate brilliantly- coloured and protected species, the males retaining "the " normal aspect of their immediate congeners." It is here obvious that the successive variations by which the female has been modified have been transmitted to her alone. It is, however, probable that some of the many successive variations would have been transmitted to, and developed in, the males had not such males been eliminated by being thus rendered less attractive to the females; so that only those variations were preserved which were from the fii'st strictly limited in their transmission to the female sex. We have a partial illus- tration of these remarks in a statement by Mr. Belt;='- that '^ Wallace, 'Transact. Linn. Soc' 163-168. This latter essay is valu- vol. XXV. 1865, p. 1 ; also ' Transact, able, as Mr. Riley here discusses all Ent. Soc' vol. iv. (3rd series), 1867, the objections which have been p. 301. Trimen, ' Linn. Transact.' raised against Mr. Bates' theory, vol. xxvi. 1869, p. 497. Riley, , ^- ' The Naturalist in Nicaragua, 'Third Annual Report on the Noxi- 1874, p. 385. ous Insects of Missouri,' 1871, pp OiiAP. Xr. Butterjiies and Moths. 325 the males of some of the Leptalides, which imitate protected species, still retain in a concealed manner some of their original characters. Thus in the males ''the npper half of the lower " wing is of a pure white, whilst all the rest of the wings is " barred and sjDottcd with black, red and yellow, like the species " they mimic. The females have not this white patch, and the " males usually conceal it by covering it with the ^^pper wing, " so that I cannot imagine its being of any other use to them " than as an attraction in courtship, when they exhibit it to the " females, and thus gratify their deep-seated preference for the " normal colour of the Order to which the Leptalides belong." Briijlit Colours of Caterpillars. — Whilst reflecting on the beauty of many butterflies, it occurred to me that some cater- pillars were splendidly coloured ; and as sexual selection could not possibly have here acted, it appeared rash to attribute the beauty of the mature insect to this agency, unless the bright colours of their larvas could be somehow explained. In the first place, it may be observed that the colours of caterpillars do not stand in any close correlation with those of the mature insect. Secondly, their bright colours do not serve in any ordinary manner as a protection. Mr. Bates informs me, as an instance of this, that the most conspicuous caterpillar which he ever beheld (that of a Sphinx) lived on the large green leaves of a tree on the open llanos of South America ; ]t was about four inches in length, transversely banded with black and yellow, and with its head, legs, and tail of a bright red. Hence it caught the eye of any one who passed by, even at the distance of many yards, and no doubt that of every passing bird. I then applied to Mr. Wallace, who has an innate genius for solving difficulties. After some consideration he replied : " Most *' caterpillars require protection, as may be inferred from some *' kinds being furnished with spines or irritating hairs, and " from many being coloured green like the leaves on which they " feed, or being curiously like the twigs of the trees on which they " live." Another instance of protection, furnished me by Mr, J. Mansel Weale, may be added, namely, that there is a caterpillar of a moth which lives on the mimosas in South Africa, and fabricates for itself a case quite indistinguishable from the surrounding thorns. From such considerations Mr. Wallace thought it probable that conspicuously-coloured oateri^illars were protected by having a nauseous taste ; but as their skin is extremely tender, and as their intestines readily protrude from a wound, a slight peck from the beak of a bird would be as fatal to them as if they had been devoured. Hence, as 326 The Descent of Man. Paet II Mr. Wallace remarks, " distastefulness alone would be insufficient " to protect a caterpillar unless some outward sign indicated to " its would-be destroyer that its prey was a disgusting morsel." Under these circumstances it would be highly advantageous to a caterpillar to be instantaneously and certainly recognised as unpalatable by all birds and other animals. Thus the most gaudy colours would be serviceable, and might have been gained by variation and the sui'vival of the most easily-re- cognised individuals. This hypothesis appears at first sight very bold, but when it was brought before the Entomological Society ^^ it was supported by various statements ; and Mr. J. Jenner Weir, who keeps a large number of birds in an aviary, informs me that he has made many trials, and finds no exception to the rule, that all caterpillars of nocturnal and retiring habits with smooth skins, all of a green colour, and all which imitate twigs, are greedily devoured by his birds. The hairy and spinose kinds are in variably rejected, as were four conspicuously-coloured species. When the birds rejected a caterpillar, they plainly shewed, by shaking their heads, and cleansing their beaks, that they were disgusted by the taste.^ Three conspicuous kinds of cater- pillars and moths were also given to some lizards and frogs, by Mr. A. Butler, and were rejected, though other kinds were eagerly eaten. Thus the probability of Mr. Wallace's view is confirmed, namely, that certain caterpillars have been made conspicuous for their own good, so as to be easily recognised by their enemies, on nearly the same principle that poisons are sold in coloured bottles by druggists for the good of man. We cannot, however, at present thus explain the elegant diversity in the colours of many caterpillars ; but any species which had at some former period acquired a dull, mottled, or strijDed appear- ance, either in imitation of surrounding objects, or from the direct action of climate, &c., almost certainly would not become uniform in colour, when its tints were rendered intense and bright ; for in order to make a caterpillar merely conspicuous, there would be no selection in any definite direction. Summary and Concluding Bemarhs on Insects. — Looking back 23 * Proc. Entomolog. Soc* Dec. analogous facts in the ' Third An- 3rd, 1866, p. xlv., and March 4th, nual Report on the Noxious Insects 1867, p. Ixxx. of Missouri,' 1871, p. 148. Some ^'^ See Mr. J. Jenner Weir's opposed cases are, however, given hy paper on Insects and Insectivorous Dr. Wallace and M, H. d'Orville ; Birds, in ' Transact. Ent. Soc' 1869, see 'Zoological Record,' 1869, p. p. 21 ; also Mr. Butler's paper, 349. ibid. p. 27. Mr. Riley has given Chap. XI. Stivimary on Insects. 327 to the several Orders, we see that the sexes often differ in various characters, the meaning of which is not in the least understood. The sexes, also, often differ in their organs of sense and means of locomotion, so that the males may quickly discover and reach the females. They differ still oftener in the males possessing diversified contrivances for retaining the females when found. We are, however, here concerned only in a secondary degree with sexual differences of these kinds. In almost all the Orders, the males of some species, even of weak and delicate kinds, are known to be highly pugnacious ; and some few are furnished with special weapons for fighting with their rivals. But the law of battle does not prevail nearly so widely with insects as with the higher animals. Hence it probably arises, that it is in only a few cases that the males have been rendered larger and stronger than the females. On the contrary, they are usually smaller, so that they may be developed within a shorter time, to be ready in large numbers for the emergence of the females. In two families of the Homoptera and in three of the Orthop- tera, the males alone possess sound-producing organs in an efficient state. These are used incessantly during the breeding- season, not only for calling the females, but apparently for charming or exciting them in rivalry with other males. No one who admits the agency of selection of any kind, will, after reading the above discussion, dispute that these musical instru- ments have been acquired through sexual selection. In four other Orders the members of one sex, or more commonly of both sexes, are provided with organs for producing various sounds, which apparently serve merely as call-notes. When both sexes are thus provided, the individuals which were able to make the loudest or most continuous noise would gain partners before those which were less noisy, so that their organs have probably been gained through sexual selection. It is instructive to reflect on the wonderful diversity of the means for producing sound, possessed by the males alone, or by both sexes, in no less than six Orders. We thus learn how effectual sexual selection has been in leading to modifications which sometimes, as with the Homoptera, relate to important parts of the organisation. From the reasons assigned in the last chapter, it is probable that the great horns possessed by the males of many Lamel- licorn, and some other beetles, have been acquired as ornaments. From the small size of insects, we are apt to undervalue their appearance. If we could imagine a male Chalcosoma (fig. 16), with its polished bronzed coat of mail, and its vast complex 328 The Descent of Man. Paet II. horns, magnified to the size of a horse, or even of a dog, it would be one of the most imposing animals in the world. The colouring of insects is a complex and obscure subject. When the male differs slightly from the female, and neither are briUiantly-coloured, it is probable that the sexes have varied in a slightly different manner, and that the variations have been transmitted by each sex to the same, without any benefit or evil thus accruing. When the male is brilliantly-coloured and difi"ers conspicuously from the female, as with some dragon-flies and many butterflies, it is probable that he owes his colours to sexual selection ; whilst the female has retained a primordial or very ancient type of colouring, slightly modified by the agencies before explained. But in some cases the female has a^Dparently been made obscure by variations transmitted to her alone, as a means of direct protection ; and it is almost certain that she has sometimes been made brilliant, so as to imitate other protected species inhabiting the same district. When the sexes resemble each other and both are obscurely coloured, there is no doubt that they have been in a multitude of cases so coloured for the sake of protection. So it is in some instances when both are brightly-coloured, for they thus imitate protected species, or resemble surrounding objects such as flowers; or they give notice to their enemies that they are unpalatable. In other cases in which the sexes resemble each other and are both brilliant, especially when the colours are arranged for display, we may conclude that they have been gained by the male sex as an attraction, and have been transferred to the female. We are more especially led to this conclusion whenever the same typo of coloration* prevails throughout a whole group, and we find that the males of some species difier widely in colour from the females, whilst others differ slightly or not at all, with intermediate gradations connecting these extreme states. In the same manner as bright colours have often been partially transferred from the males to the females, so it has been with the extraordinary horns of many Lamellicorn and some other beetles. So again, the sound-producing organs proper to the males of the Homoptera and Orthoptera have generally been transferred in a rudimentary, or even in a nearly perfect condition, to the females; yet not sufficiently perfect to be of any use. It is also an interesting fact, as bearing on sexual selection, that the stridulating organs of certain male Orthoptera are not fully developed until the last moult; and that the colours of certain male dragon-flies are not fully develoi^ed until some little time after their emergence from the pupal state, and when they are ready to breed. Chap. XI. Summary on Insects. 329 Sexual selection implies that the more attractive individuals are preferred by the opposite sex ; and as with insects, when the sexes differ, it is the male which, with some rare exceptions, is the more ornamented, and departs more from the type to which the species belongs ; — and as it is the male which searches eagerly for the female, we must suppose that the females habitually or occasionally prefer the more beautiful males, and that these have thus acquired their beauty. That the females in most or all the orders would have the power of rejecting any particular male, is probable from the many singular con- trivances possessed by the males, such as great jaws, adhesive cushions, spines, elongated legs, &c., for seizing the female ; for these contrivances shew that there is some difficulty in the act, so that her concurrence would seem necessary. Judging from what we know of the perceptive powers and affections of various insects, there is no antecedent improbability in sexual selection having come largely into play ; but we have as yet no direct evidence on this head, and some facts are opposed to the belief. Nevertheless, when we see many males pursuing the same female, we can hardly believe that the pairing is left to blind chance — that the female exerts no choice, and is not influenced by the gorgeous colours or other ornaments with which the male is decorated. If we admit that the females of the Homoptera and Orthoptera appreciate the musical tones of their male partners, and that the various instruments have been perfected through sexual se- lection, there is little improbability in the females of other insects appreciating beauty in form or colour, and consequently in such characters having been thus gained by the males. But from the circumstance of colour being so variable, and from its having been so often modified for the sake of protection, it is difficult to decide in how large a jn-oportion of cases sexual selection has played a part. This is more especially difficult in those Orders, such as Orthoptera, HymenoiDtera, and Coleop- tera, in which the two sexes rarely differ much in colour ; for we are then left to mere analogy. With the Coleoptera, however, as before remarked, it is in the great Lamellicorn group, placed by some authors at the head of the Order, and in which we sometimes see a mutual attachment between the sexes, that we find the males of some species possessing weapons for sexual strife, others furnished with wonderful horns, many with stridu- lating organs, and others ornamented with splendid metallic tints. Hence it seems probable that all these characters have been gained through the same means, namely sexual selection. With butterflies we have the best evidence, as the males 330 The Descent of Man. Paet II. sometimes take pains to display their beautiful colours; and we cannot believe that they would act thus, unless the display was of use to them in their courtship. When we treat of Birds, we shall see that they present in their secondary sexual characters the closest analogy with insects. Thus, many male birds are highly pugnacious, and some are furnished with special weapons for fighting with their rivals. They possess organs which are used dui'ing the breeding- season for producing vocal and instrumental music. They are frequently ornamented with combs, horns, wattles and plumes of the most diversified kinds, and are decorated with beautiful colours, all evidently for the sake of display. "We shall find that, as with insects, both sexes in certain groups are equally beautiful, and are equally provided with ornaments which are usually confined to the male sex. In other groups both sexes are equally plain-coloured and unornamented. Lastly, in some few anomalous cases, the females are more beautiful than the males. We shall often find, in the same group of birds, every gradation from no diff"erence between the sexes, to an extreme difference. We shall see that female birds, like female insects, often possess more or less plain traces or rudiments of characters which properly belong to the males and are of use only to them. The analogy, indeed, in all these respects between birds and insects is curiously close. W^hatever explanation applies to the one class probably applies to the other ; and this explanation, as we shall hereafter attempt to shew in fui'ther detail, is sexual selection. CHAPTEK XII. Secondary Sexual Characters of Fishes, Amphibians, AND Reptiles. Fishes: Courtship and battles of the males — Larger size of the females — Males, bright colours and ornamental appendages; other strange characters — Colours and appendages acquired by the males during the breeding-season alone — Fishes with both sexes brilliantly coloured — Protective colours — The less conspicuous colours of the female cannot be accounted for on the principle of protection — Male tishes building nests, and taking charge of the ova and young. Ajniphibians : Dif- ferences in structure and colour between the sexes — Vocal organs. Reptiles : Chelonians — Crocodiles — Snakes, colours in some cases pro- tective— Lizards, battles of — Ornamental appendages — Strange dif- ferences in structure between the sexes — Colours — Sexual differences almost as great as with birds. We have now arrived at the great sub-kingdom of the Vertebrata, and will commence with the lowest class, that of Fishes. The Chap. XII. Fishes. 33 1 males of Plagiostomous fishes (sharks, rays) and of Chimaeroid fislies are provided with claspers which serve to retain the female, like the various structures possessed by many of the lower animals. Besides the claspers, the males of many rays have clusters of strong sharp spines on their heads, and several rows along " the upper outer surface of their pectoral fins." These are present in the males of some species, which have other parts of their bodies smooth. They are only temporarily developed during the breeding-season ; and Dr. GUnther suspects that they are brought into action as prehensile organs by the doubling inwards and downwards of the two sides of the body. It is a remarkable fact that the females and not the males of some species, as of Ilaia davata, have their backs studded with large hook-formed spines.^ The males alone of the capehn {Mallotus villosus, one of Salmonidse), are provided with a ridge of closely-set, brush-like scales, by the aid of which two males, one on each side, hold the female, whilst she runs with great swiftness on the sandy beach, and there deposits her si3awn.^ The widely distinct Monaccmthus scopas presents a somewhat analogous structure. The male, as Dr. GiJnther informs me, has a cluster of stiff, straight spines, like those of a comb, on the sides of the tail ; and these in a specimen six inches long were nearly one and a half inches in length ; the female has in the same place a cluster of bristles, which may be compared with those of a tooth-brush. In another species, M. peronii, the male has a brush like that possessed by the female of the last species, whilst the sides of the tail in the female are smooth. In some other species of the same genus the tail can be perceived to be a little roughened in the male and perfectly smooth in the female; and lastly in others, both sexes have smooth sides. The males of many fish fight for the possession of the females. Thus the male stickleback (Gasterosfeus leiurus) has been de- scribed as " mad with delight," when the female comes out of her hiding-place and surveys the nest which he has made for her. *' He darts round her in every direction, then to his accumulated *' materials for the nest, then back again in an instant ; and as " she does not advance he endeavours to push her with his snout, " and then tries to pull her by the tail and side- spine to the nest."^ » Yarrell's 'Hist, of British 1871, p. 119. Fishes,' vol. ii. 1836, pp. 417, 425, 3 See Mr. R. Waringtoii's in- 436. Dr. Giinther informs me that terestiug articles in ' Annals and the spines in R. clacata are peculiar Mag. of Nat. Hist.' Oct. 1852 and to the female. Nov. 1855. - * The American Naturalist,' April 332 The Descent of Man. Part II. The males are said to be polygamists ;^ they are extraordinarily bold and pugnacious, whilst " the females are quite pacific." Their battles are at times desperate ; ''for these puny com- " batants fasten tight on each other for several seconds, tumbling " over and over again, until their strength appears completely " exhausted." With the rough-tailed stickleback (G^. trachurus) the males whilst fighting swim round and round each other, biting and endeavouring to pierce each other with their raised lateral spines. The same writer adds,^ " the bite of these little " furies is very severe. They also use their lateral spines with " such fatal efiect, that I have seen one during a battle absolutely " rip his opponent quite open, so that he sank to the bottom and " died." When a fish is conquered, " his gallant bearing forsakes " him ; his gay colours fade away ; and he hides his disgrace "among his peaceable companions, but is for some time the " constant object of his conqueror's persecution." The male salmon is as pugnacious as the little stickleback ; and so is the male trout, as I hear from Dr. Giinther. Mr. Shaw saw a violent contest between two male salmon which lasted the whole day ; and Mr. R. Buist, Sui3erintendent of Fisheries, informs me that he has often watched from the bridge at Perth the males driving away their rivals, whilst the females were spawning. The males " are constantly fighting and tearing each " other on the spawning-beds, and many so injure each other as " to cause the death of numbers, many being seen swimming near " the banks of the river in a state of exhaustion, and apparently " in a dying state."^ Mr. Buist informs me, that in June 1868, the keeper of the Stormontfield breeding-ponds visited the northern Tyne and found about 300 dead salmon, all of which with one exception wei-e males ; and he was convinced that they had lost their lives by fighting. The most curious point about the male salmon is that during the breeding-season, besides a slight change in colour, " the " lower jaw elongates, and a cartilaginous projection turns " upwards from the point, which, when the jaws are closed, " occupies a deep cavity between the intermaxillary bones of the upper jaw." '^ (Figs. 27 and 28.) In our salmon this change of structure lasts only during the breeding-season; but in the ■* Xoel Humphreys, 'River Gar- experienced observer (Scrope's * Days dens,' 1857. of Salmon Fishing/ p. 60) remarks ^ Loudon's ' Mag. of Nat. History,' that lilie the stag, the male would, vol. iii. 1830, p. 331. if he could, keep all other males « 'The Field,' June 29th, 18G7. away. For Mr. Shaw's statement, see ^ Yarrell, ' History of British 'Edinburgh Review,' 1843. Another Fishes,' vol. ii. 1836, p. 10. Ceap. XIL Fishes. 333 Salmo hjcabdon of N.-W. America the change, as Mr. J. K. Lord^ believes, is permanent, and best marked in the older males which have previously ascended the rivers. In these old males the jaw becomes developed into an immense hook-like projection, and Fig. 27. Head of male common salmon (Salmo salar) during the breeding-season. TThis drawing, as well as all the others in the present chaptnr, have been executed by the well-known artist, Mr. G. Ford, from specimens in the British Museum, under the kind superintendence of Dr. Gtinther.J the teeth grow into regular fangs, often more than half an inch in length. With the European salmon, according to Uv. Lloyd,^ the temporary hook-like structure serves to strengthen and * 'The Naturalist in Vancouver's ^ 'Scandinavian Adventures,' vol Island,' vol. i. 1866, p. 54. i. 1854, pp. 100, 104. 334 The Descent of Man, PartIL protect the jaws, when one male charges another with wonderful violence ; but the greatly developed teeth of the male American salmon may be compared with the tusks of many male mammals, and they indicate an oifensive rather than a jDrotectivc purpose. Fig 28 Head of female salmon. The salmon is not the only fish in which the teeth differ in the two sexes ; as this is the case with many rays. In the thornback (^Eam davatci) the adult male has sharp, pointed teeth, directed backwards, whilst those of the female are broad and flat, and form a pavement ; so that tbese teeth differ in the two sexes of the same species more than is usual in distinct genera of the same family. The teeth of the male become sharp only when he is adult : whilst young they are broad and fiat Cu AP. X 1 1. Fishes. 335 like those of the female. As so frequently occurs with secondary sexual characters, both sexes of some species of rays (for instance R. hatis), when adult, possess sharjD pointed teeth ; and here a character, proper to and primarily gained by the male, appears to have been transmitted to the offspring of both sexes. The teeth are likewise pointed in both sexes of 11. maculata, but only when quite adult ; the males acquiring them at an earlier age than the females. We shall hereafter meet with analogous cases in certain birds, in which the male acquires the plumage common to both sexes when adult, at a somewhat earlier age than does the female. With other species of rays the males even when old never possess sharp teeth, and consequently the adults of both sexes are provided with broad, flat teeth like those of the young, and like those of the mature females of the above-mentioned species.^^ As the rays are bold, strong and voracious fish, wo may suspect that the males require their sharp teeth for fighting with their rivals ; but as they possess many parts modified and adapted for the prehension of the female, it is possible that their teeth may be used for this purpose. In regard to size, M. Carbonnier " maintains that the female of almost all fishes is larger than the male ; and Dr. Giinther does not know of a single instance in which the male is actually larger than the female. With some Cyprinodonts the male is not even half as large. As in many kinds of fishes the males habitually fight together, it is surprising that they have not generally become larger and stronger than the females through the effects of sexual selection. The males suffer from their small size, for according to M. Carbonnier, they are liable to be devoured by the females of their own species when carnivorous, and no doubt by other species. Increased size must be in some manner of more importance to the females, than strength and size are to the males for fighting with other males; and this perhaps is to allow of the production of a vast number of ova. In many species the male alone is ornamented with bright colours; or these are much brighter in the male than the female. The male, also, is sometimes provided with appendages which appear to be of no more use to him for the ordinary purposes of life, than are the tail feathers to the peacock. I am indebted for most of the following facts to the kindness of Dr. Giinther. There is reason to suspect that many tropical fishes differ sexually in colour and structure ; and there are some striking cases with our British fishes. The male Calliojiymns lyra ^•^ See Yarrell's account of the cellent figure, and p. 422, 432. rays in his ' Hist, of British Fishes,' ^^ As quoted in 'The Fanner, vol. ii. 1836, p. 410, with an ex- 1868, p. 369. 336 The Descent of Man. Part II. has been called the gemmeoiis dragonet " from its brilliant gem- " like colours/' When fresh caught from the sea the body is yellow of various shades, striped and spotted with vivid blue on the head ; the dorsal fins are pale brown with dark longitudinal bands; the ventral, caudal, and anal fins being bluish-black. The female, or sordid dragonet, was considered by Linnseus, and by many subsequent naturalists, as a distinct species ; it is of a dingy reddish-brown, with the dorsal fin brown and the other Fig. 29. Callionymus lyra. Upper figure, male ; lower figure, female. N.B. The lower figure is more reduced than the upper. fins white. The sexes differ also in the proportional size of the head and mouth, and in the position of the eyes ;^^ but the most striking difference is the extraordinary elongation in the male (fig. 29) of the dorsal fin. I\Ir. W. SaviUe Kent remarks that this " singular appendage appears from my observations " of the species in confinement, to be subservient to the same " end as the wattles, crests, and other abnormal adjuncts of " the male in gallinaceous birds, for the jDurpose of fascinating '- I have drawn up this description from Yarrell's ' British Fishes,'voI. 1. 1836, pp. 261 and 2(36. Chap. XII. Fishes. 337 ** their mates." ^^ The young males resemble the adult females in structure and colour. Throughout the genus Callionymus/* the male is generally much more brightly spotted than the female, and in several species, not only the dorsal, but the anal fin is much elongated in the males. The male of the Coitm scorpius, or sea-scorpion, is slenderer and smaller than the female. There is also a great difference in colour between them. It is difficult, as Mr. Lloyd ^^ remarks, " for any one, who has not seen this fish during the spawning- " season, when its hues are brightest, to conceive the admixture " of brilliaut colours with which it, in other respects so ill- *' favoured, is at that time adorned." Both sexes of the Lahrus mixtiis, although very diiferent in colour, are beautiful; the male being oraoge with bright blue stripes, and the female bright red with some black spots on the back. Fig. 30. Xiphophorus Hellerii. Upper figure, male ; lower figure, female. In the very distinci; family of the Cyprinodoutidse— inhabitants of the fresh waters of foreign lands— the sexes sometimes differ much in various characters. In the male of the MolUeuesia petenensis,'^^ the dorsal fin is greatly developed and is marked '6 With respect to this and the following; species I am indebted to Dr. Giinther for information: see '3 'Nature,' July 1873, p. 264. ** ' Catalogue of Acanth. Fishes in the British Museum,' by Dr. Giinther, 1861, pp. 138-151. ^^ * Game Birds of Sweden,' &c.. 1867, p. 466. also his paper on the 'Fishes of Central America,' in 'Transact. Zoolog. Soc' vol. y\. 1868, p. 485. 338 The Descent of Man. - Part IT. with a row of large, round, ocellated, bright-coloured spots; whilst the same fin in the female is smaller, of a different shape, and marked only with irregularly curved brown spots. In the male the basal margin of the anal fin is also a little produced and dark coloured. In the male of an allied form, the Xipho- phorns Helhrli (fig. 30), the inferior margin of the caudal fin is developed into a long filament, which, as I hear from Dr. Giinther, is striped with bright colours. This filament does not contain any muscles, and apparently cannot be of any direct use to the fish. As in the case of the Callionymus, the males whilst young resemble the adult females in colour and structure. Sexual differences such as these may be strictly compared with those which are so frequent with gallinaceous birds.^''' In a siluroid fish, inhabiting the fresh waters of South America, the Plecostomus harbatus^^ (fig. 31), the male has its mouth and inter-operculum fringed with a beard of stiff hairs, of which the female shows hardly a trace. These hairs are of the nature of scales. In another species of the same genus, soft flexible ten- tacles project from the front part of the head of the male, which are absent in the female. These tentacles are prolongations of the true skin, and therefore are not homologous with the stiff hairs of the former species ; but it can hardly be doubted that both serve the same purpose. What this purpose may be, it is difficult to conjecture ; ornament does not here seem probable, but we can hardly suppose that stiff hairs and flexible filaments can be useful in any ordinary way to the males alone. In that strange monster, the Chimcera monsfrom, the male has a hook- shaped bone on the top of the head, directed forwards, with its end rounded and covered with sharp spines ; in the female " this " crown is altogether absent," but what its use may be to the male is utterly unknown.^'' The structures as yet referred to are permanent in the male after he has arrived at maturity ; but with some Blennies, and in another aUied genus,^° a crest is developed on the head of the male only during the breeding-season, and the body at the same time becomes more brightly-coloured. There can be little doubt that this crest serves as a temporary sexunl ornament, for the female does not exhibit a trace of it. In other species of the same genus both sexes possess a crest, and in at least one s^Decies '^ Dr. Giinther makes this re- Water,' July 1368, p. 377, with a mark; * Catalogue of Fishes in the figure. Many other cases could be British Museum,' vol. iii. 1861, p. added of structures peculiar to the 141. male, of which the uses are not ^* See Dr. Giinther on this genus, known, m 'Proc. Zoolog. Soc' 1868, p. 232. =» Dr. Giinther, ' Catalogue of l^ F. Buckland, in * Land and Fishes,' vol. iii. pp. 221 and 240. Chap. XII. Fishes. 339 Fig. 31. Plecostomus barbatus. L i-p-n i.b"' ..3 ; lower figure, female. 340 The Descent of Man. Part II. neither sex is thus provided. In many of the Chromidse, for instance in Geophagus and especially in Cichla, the males, as I hear from Professor Agassiz/^ have a conspicuous protuberance on the forehead, which is wholly wanting in the females and in the young males. Professor Agassiz adds, " I have often " observed these fishes at the time of spawning when the ;pro- " tuberance is largest, and at other seasons when it is totally *' wanting, and the two sexes shew no difference whatever in the " outline of the profile of the head.- I never could ascertain that " it subserves any special function, and the Indians on the " Amazon know nothing about its use." These protuberances resemble, in their periodical appearance, the fleshy caruncles on the heads of certain birds ; but whether they serve as ornaments must remain at present doubtful. I hear from Professor Agassiz and Dr. Giinther, that the males of those fishes, which differ permanently in colour from the females, often become more brilliant during the breeding-season. This is likewise the case with a multitude of fishes, the sexes of which are identical in colour at all other seasons of the year, The tench, roach, and perch may be given as instances. The male salmon at this season is "marked on the cheeks with *'■ orange-coloured stripes, which give it the ajDpearance of a ** Labrus, and the body partakes of a golden orange tinge. The " females are dark in colour, and are commonly called black- '*'fish."2^ An analogous and even greater change takes place with the Salmo eriox or bull trout ; the males of the char (iS. umhla) are likewise at this season rather brighter in colour than the females.^^ The colours of the pike (Esox reticulatus) of the United States, especially of the male, become, during the breeding-season, exceedingly intense, brilliant, and iridescent.'^* Another striking instance out of many is afforded by the male stickleback (Gasferosteus leiurus), which is described by Mr. Warington,^^ as being then "beautiful beyond description." The back and eyes of the female are simply brown, and the belly white. The eyes of the male, on the other hand, are " of the " most splendid green, having a metallic lustre like the green " feathers of some humming-birds. The throat and belly are " of a bright crimson, the back of an ashy-green, and the whole " fish appears as though it were somewhat translucent and 2' See also * A Journey in Brazil,' Mag. of Nat. History,' vol. vi. 1841, by Prof, and Mrs. Agassiz, 1868, p. p. 440. 220. 24 'The American Agriculturalist,' " Yarrell, * British Fishes,' vol. 1868, p. 100. ii. 1836, pp. 10, 12, 35. 25 . Annals and Mag. of Nat. Hist.' 2^ W. Thompson, in 'Annals and Oct. 1852. Chap. XII. Fishes. 341 " glowed with an internal incandescence." After the breeding- season these colours all change, the throat and belly become of a paler red, the back more green, and the glowing tints subside. With respect to the courtship of fishes, other cases have been observed since the first edition of this book appeared, besides that already given of the stickleback. Mr. W. S. Kent says that the male of the Lalwus mixtns, which, as we have seen, differs in colour from the female, makes " a deep hollow in the sand of the " tank, and then endeavours in the most persuasive manner to in- " duce a female of the same species to share it with him, swim- " ming backwards and forwards between her and the completed '' nest, and x^lainly exhibiting the greatest anxiety for her to follow." The males of Cantharus lineatus become, during the breeding- season, of deep leaden-black ; they then retire from the shoal, and excavate a hollow as a nest. "Each male now mounts vigilant " guard over his respective hollow, and vigorously attacks and *• drives away any other fish of the same sex. Towards his com- " panions of the opposite sex his conduct is far different ; many of " the latter are now distended with spawn, and these he endeavours " by all the meaus in his power to lure singly to his prepared " hollow, and there to deposit the myriad ova with which they are " laden, which he then protects and guards with the greatest care.^" A more striking case of courtship, as well as of display, by the males of a Chinese Macropus has been given by M. Carbonnier, who carefully observed these fishes under confinement.-^ The males are most beautifully coloured, more so than the females. During the breeding-season they contend for the possession of the females; and, in the act of courtship, expand their fins, which are spotted and ornamented with brightly coloured rays, in the same manner, according to M. Carbonnier, as the peacock. They then also bound about the females with much vivacity, and appear by " I'etalage de leurs vives couleurs chercher a attirer " I'attention des femelles, lesquelles ne paraissaient indifferentes " a ce manege, elles nageaient avec une molle lenteur vers les " males et semblaient se comjDlaire dans leur voisinage." After the male has won his bride, he makes a little disc of froth by blowing air and mucus out of his mouth. He then collects the fertilised ova, drojDped by the female, in his mouth ; and this caused M. Carbonnier much alarm, as he thought that they were going to be devoured. But the male soon deposits them in the disc of froth, afterwards guarding them, repairing the froth, and taking care of the young when hatched. I mention these par- ticulars because, as we shall presently see, there are fishes, the 26 < Nature,' May, 1873, p. 25. 27 .Bull, de la Soc. d'Acclimat.' Paris, July 1869, and Jan. 1870. 342 The Descent of Man. Part II. males of whicli hatch their eggs in their mouths ; and those who do not believe in the principle of gradual evolution might ask how could such a habit have originated ; but the diflficulty is much diminished when we know that there are fishes which thus collect and carry the eggs; for if delayed by any cause in depositing them, the habit of hatching them in their mouths might have been acquired. To return to our more immediate subject. The case stands thus : female fishes, as far as I can learn, never willingly spawn except in the presence of the males ; and the males never fertilise the ova except in the presence of the females. The males fight for the possession of the females. In many species, the males whilst young resemble the females in colour ; but when adult become much more brilliant, and retain their colours throughout life. In other species the males become brighter than the females and otherwise more highly ornamented, only during the season of love. The males sedulously court the females, and in one case, as we have seen, take pains in displaying their beauty before them. Can it be believed that thej would thus act to no purpose during their courtship ? And this would be the case, unless the females exert some choice and select those males which please or excite them most. If the female exerts such choice, all the above facts on the ornamentation of the males become at once intelligible by the aid of sexual selection. We have next to enquire whether this view of the bright colours of certain male fishes having been acquired through sexual selection can, through the law of the equal transmission of characters to both sexes, be extended to those groups in which the males and females are brilliant in the same, or nearly the same degree and manner. In such a genus as Labrus, which includes some of the most splendid fishes in the world — for instance, the Peacock Labrus {L. -pavo), described,-^ with pardonable exaggera- tion, as formed of polished scales of gold, encrusting lajDis-lazuli, rubies, sapphires, emeralds, and amethysts — we may, with much probability, accept this belief; for we have seen that the sexes in at least one species of the genus differ greatly in colour. With some fishes, as with many of the lowest animals, splendid colours may be the direct result of the nature of their tissues and of the surrounding conditions, without the aid of selection of any kind. The gold-fish {Cyprinus auratus), judging from the analogy of the golden variety of the common carp, is perhaps a case in point, as it may owe its splendid colours to a single abrupt variation, due to the conditions to which this fish has been subjected under 28 Bory de Saint Vincent, in 'Diet. Class. d'Hist. Nat.' torn. ix. 1826 p. 151. Chap. XII. Fishes. 343 confinement. It is, however, more probable that these colours have been intensified through artificial selection, as this species has been carefully bred in China from a remote period.^^ Under natural conditions it does not seem probable that beings so highly organised as fishes, and which live under such complex relations, should become brilliantly coloured without suffering some evil or receiving some benefit from so great a change, and consequently without the intervention of natural selection. What, then, are we to conclude in regard to the many fishes, both sexes of which are splendidly coloured? Mr. Wallace ^'^ believes that the species which frequent reefs, where corals and other brightly-coloured organisms abound, are brightly coloured in order to escape detection by their enemies ; but according to my recollection they were thus rendered highly conspicuous. In the fresh-waters of the tropics there are no brilliantly- coloured corals or other organisms for the fishes to resemble ; yet many species in the Amazons are beautifully coloured, and many of the carnivorous Cyprinidse in India are ornamented with "bright longitudinal lines of various tints." ^^ Mr. M'Clel- land, in describing these fishes, goes so far as to suppose that " the peculiar brilliancy of their colours " serves as " a better " mark for king-fishers, terns, and other birds which are " destined to keep the number of these fishes in check ; " but at the present day few naturalists will admit that any animal has been made conspicuous as an aid to its own destruction. It is possible that certain fishes may have been rendered conspicuous in order to warn birds and beasts of prey that they were unpalatable, as explained when treating of caterpillars; but it is not, I believe, known that any fish, at least any fresh-water fish, is rejected from being distasteful to fish-devouring animals. On the whole, the most probable view in regard to the fishes, of which both sexes are brilliantly coloured, is that their colours were acquired by the males as a sexual ornament, and were transferred equally, or nearly so, to the other sex. "^ Owing to some remai*ks on this has been " produced at Hangchow a subject, made in my work ' On the " variety called the fire-fish, from its Variation of Animals under Domesti- "intensely red colour. It is uni- cation,' Mr. W. F. Mayers (' Chinese " versally admired, and there is not Notes and Queries,' Aug. 1868, p. " a household where it is not cul- 123) has searched the ancient " tivated, w rivalry as to its colour, (.•hinese encyclopedias. He finds " and as a source of profit." that gold-fish were first reared iu ^^ * Westminster Review,' July confinement during the Sung Dy- 1867, p. 7. nasty, which commenced A.D. 960. ^i < Judian Cyprinidaj,' by Mr. J, In the year 1129 these fishes M'Clelland, 'Asiatic Researches, abounded. In another place it is vol. xix. part ii. 1839, p. 230. said that since the year 1548 there 344 The Descent of Ma7L Part II. We have now to consider wliether, when the male differs in a marked manner from the female in colour or in other orna- ments, he alone has been modified, the variations being inherited by his male offspring alone; or whether the female has been specially modified and rendered inconspicuous for the sake of jn-otection, such modifications being inherited only by the females. It is impossible to doubt that colour has been gained by many fishes as a protection : no one can examine the speckled upper surface of a flounder, and overlook its resemblance to the sandy bed of the sea on which it lives. Certain fishes, moreover, can through the action of the nervous system, change their colours in adaptation to surrounding objects, and that within a short time.^^ One of the most striking instances ever recorded of an animal being protected by its colour (as far as it can be judged of in preserved specimens), as well as by its form, is that given by Dr. Giinther^^ of a pipe-fish, which, with its reddish streaming filaments, is hardly distinguishable from the sea-weed to which it clings with its prehensile tail. But the question now imder consideration is whether the females alone have been modified for this object. We can see that one sex will not be modified through natural selection for the sake of protection more than the other, supposing both to vary, unless one sex is exposed for a longer period to danger, or has less power of escaping from such danger than the other; and it does not appear that with fishes the sexes differ in these respects. As far as there is any difference, the males, from being generally smaller and from wandering more about, are exposed to greater danger than the females; and yet, when the sexes differ, the males are almost always the more conspicuously coloured. The ova are fertilised immediately after being deposited ; and when this process lasts for several days, as in the case of the salmon,^* the female, during the whole time, is attended by the male. After the ova are fertilised they are, in most cases, left unprotected by both parents, so that the males and females, as far as oviposition is concerned, are equally exposed to danger, and both are equally important for the production of fertile ova ; consequently the more or less brightly-coloured individuals of either sex would be equally liable to be destroyed or preserved, and both would have an equal influence on the colours of their offspring. Certain fishes, belonging to several families, make nests, and some of them take care of their young when hatched. Both 32 G. Pouchet, L'Institut. Nov. 1, 327, pi. xiv. anci xv. 1871, p. 134. ='•' Yarrell, ' British Fishes,' rcl. 33 'Proc. Zoolog. Soc' 1865, p. ii. p. 11. Chap. XII. Fishes. 345 sexes of the bright coloured Crenilabrus massa and mdopa work together in building their nests with sea-weed, shells, &c.^^ But the males of certain fishes do all the work, and afterwards take exclusive charge of the young. This is the case with the dull- coloured gobies,^'' in which the sexes are not known to differ in colour, and likewise with the sticklebacks (Gasterosteus), in which the males become brilliantly coloured during the spawning season. The male of the smooth- tailed stickleback ((?. leinrus) j^erforms the duties of a nurse with exemplary care and vigilance during a long time, and is continually employed in gently leading back the young to the nest, when they stray too far. He courageously drives away all enemies, including the females of his own species. It would indeed be no small relief to the male, if the female, after depositing her eggs, were immediately devoured by some enemy, for he is forced incessantly to drive her from the nest.^^ The males of certain other fishes inhabiting South America and Ceylon, belonging to two distinct Orders, have the extra- ordinary habit of hatching within their mouths or branchial cavities, the eggs laid by the females.^® I am informed by Professor Agassiz that the males of the Amazoniaa species which follow this habit, " not only are generally brighter than " the females, but the difference is greater at the spawning-season " than at any other time." The species of Geophagus act in the same manner ; and in this genus, a conspicuous protuberance becomes developed on the forehead of the males during the breeding-season. With the various species of Chromids, as Professor Agassiz likewise informs me, sexual differences in colour may be observed, " whether they lay their eggs in the " water among aquatic plants, or deposit them in holes, leaving " them to come out witiiout further care, or build shallow nests " in the river mud, over which they sit, as our Promotis does. " It ought also to be observed that these sitters are among the " brightest species in their respective families ; for instance, " Hygrogonus is bright green, with large black ocelli, encircled " with the most brilliant red." Whether with all the species of Chromids it is the male alone which sits on the eggs is not known. It is, however, manifest that the fact of the eggs being ^^ According to the observatioas nals and Mag. of Nat. Hist.' Novem- of M. Gerbe ; see Giinther's ' Record ber 1855. of Zoolog. Literature,' 1^65, p. '* Prof. Wyman, in ' Proc*. Boston 194-. Soc. of Nat. Hist.' Sept. 15, 1857. 2^ Cuvier, ' Rfegne Animal,' vol. Also Prof. Turner, in ' Journal of ii. 1829, p. 242. Anatomy and Phys.' Nov. 1, 186(3, " See Mr. Waringtou's most p. 78. Dr. Giinther has likewise interesting description of the habits described other cases, of the Gasterosteus Iciurus, in 'An- 16 34^ The Descent of Man. Part II. protected or unprotected by the parents, has had little or no influence on the differences in colour between the sexes. It is further manifest, in all the cases in which the males take exclusive charge of the nests and young, that the destruction of the blighter-coloured males would be far more influential on the character of the race, than the destruction of the brighter- coloured females ; for the death of the male during the period of incubation or nursing would entail the death of the young, so that they could not inherit his peculiarities ; yet, in many of these very cases the males are more conspicuously coloured than the females. In most of the Lophobranchii (Pipe-fish, Hippocampi, &c.) the males have either marsupial sacks or hemispherical de- pressions on the abdomen, in which the ova laid by the female are hatched. The males also shew great attachment to their young.^^ The sexes do not commonly differ much in colour; but Dr. Gunther believes that the male Hippocampi are rather brighter than the females. The genus Solenostoma, however, offers a curious exceptional case,'*'' for the female is much more vividly-coloured and spotted than the male, and she alone has a marsupial sack and hatches the eggs; so that the female of Solenostoma differs from all the other Lophobranchii in this latter respect, and from almost all other fishes, in being more brightly-coloured than the male. It is improbable that this remarkable double inversion of character in the female should be an accidental coincidence. As the males of several fishes, which take exclusive charge of the eggs and young, are more brightly coloured than the females, and as here the female Sole- nostoma takes the same charge and is brighter than the male, it might be argued that the conspicuous colours of that sex which is the more important of the two for the welfare of the offspring, must be in some manner protective. But from the large number of fishes, of which the males are^ either permanently or period- ically brighter than the females, but whose life is not at all more important for the welfare of the species than that of the female, this view can hardly be maintained. When we treat of birds we shall meet with analogous cases, where there has been a complete inversion of the usual attributes of the two sexes, and we shall then give what appears to be the probable explanation, namely, that the males have selected the more attractive females, instead of the latter having selected, in 39 Yarrell, ' Hist, of British Fishes of Zanzibar,' by Col. Playfair, Fishes,' vol. ii. 183G, pp. 329, 338. 1866, p. 137, has re-examined the *" Dr. Gunther, since publishing specimens, and has given me the an account of this species in ' The above information. Chap. XII. Fishes. 347 accordance with the usual rule throughout the animal kingdom, the more attractive males. On the whole we may conclude, that with most fishes, in which the sexes differ in colour or in other ornamental charac- ters, the males originally varied, with their variations trans- mitted to the same sex, and accumulated through sexual selection by attracting or exciting the females. In many cases, however, such characters have been transferred, either partially or completely, to the females. In other cases, again, both sexes have been coloured alike for the sake of protection; but in no instance does it appear that the female alone has had her colours or other characters specially modified for this latter purpose. The last point which need be noticed is that fishes are known to make various noises, some of which are described as being musical. Dr. Dnfosse, who has especially attended to this subject, says that the sounds are voluntarily produced in several ways by different fishes : by the friction of the pharyngeal bones — by the vibration of certain muscles attached to the swim- bladder, which serves as a resounding board — and by the vibra- tion of the intrinsic muscles of the swim-bladder. By this latter means the Trigla produces pure and long-drawn sounds which range over nearly an octave. But the most interesting case for us is that of two species of Ophidium, in which the males alone are provided with a sound-producing apparatus, consisting of small movable bones, with proper muscles, in connection with the swim-bladder,*^ The drumming of the Umbrinas in the European seas is said to be audible from a depth of twenty fathoms ; and the fishermen of Rochelle assert " that the males " alone make the noise during the spawning-time ; and that it " is possible by imitating it, to take them without bait."*^ From this statement, and more especially from the case of Ophidium, it is almost certain that in this, the lowest class of the Verte- brata, as with so many insects and spiders, sound-producing instruments have, at least in some cases, been developed through sexual selection, as a means for bringing the sexes together. *' ' Comptes Rendus.' Tom. xlvi. the Dutch translation of this w ork 1858, p. 353. Tom. xlvii. 1858, p. (vol. ii., p. 36), gives some further 916. Tom. liv. 1862, p. 393. The particulars on the sounds made by noise made by the Umbrinas {Sciccna lishes. ciqvMa), is said by some authors to *^ The Rev. C. Kingslcy, in be more like that of a flute or organ, < Nature,' May 1870, p. 40. than drumming : Dr. Zouteveen, in 343 The Descent of Man. Part II. Amphibians. Urodela. — I will begin with the tailed amphibians. The sexes of salamanders or newts often diifer much both in colour and structure. In some species prehensile claws are develoiDed on the fore-legs of the males during the breeding-season : and at this season in the male Triton palmipes the hind-feet are pro- vided with a swimming-web, which is almost completely absorbed during the winter; so that their feet then resemble Fig. 32. Triton cristatus (half natural size, from Bell's ' British Reptiles '). Upper figure, male during the breeding-season ; lower figure, female. those of the female.^^ This structure no doubt aids the male in his eager search and pursuit of the female. Whilst courting her he rapidly vibrates the end of his tail. With our common newts (Trito7i pur/ctntus and cristntus) a deep, much indented crest is developed along the back and tail of the male during the breeding-season, which disappears during the winter. Mr. St. George Mivart informs me that it is not furnished with muscles, and therefore cannot be used for locomotion. As during the season of courtship it becomes edged with bright colours, there can hardly be a doubt that it is a masculine ornament. In many species the body presents strongly contrasted, though lurid tints, and these become more vivid during the breeding- season. The male, for instance, of our common little newt {Triton punctatus) is "brownish-grey above, passing into yellow " Bell, 'History of British Reptiles,' 2nd edit. 1849, pp. 156-159. Chap. XII. Amphibians. 349 " beneath, wliicli in the spring becomes a rich bright orange, " marked everywhere with round dark si3ots." The edge of the crest also is then tipped with bright red or violet. The female is usually of a yellowish-brown colour with scattered brown dots, and the lower surface is often quite plain.*^ The young are obscurely tinted. The ova are fertilised during the act of deposition, and are not subsequently tended by either parent. We may therefore conclude that the males have acquired their strongly-marked colours and ornamental apjiendages through sexual selection ; these being transmitted either to the male offspring alone, or to both sexes. Anura or But rack la. — With many frogs and toads the colours evidently serve as a protection, such as the bright green tints of tree-frogs and the obscure mottled shades of many terrestrial species. The most conspicuously-coloured toad which I ever saw, the rhri/niscus nigricans,*^ had the whole ui^per surface of the body as black as ink, with the soles of the feet and j^arts of . the abdomen spotted with the brightest vermilion. It crawled about the bare sandy or open grassy plains of La Plata under a scorching sun, and could not fail to catch the eye of every pass- ing creature. These colours are probably beneficial by making this animal known to all birds of prey as a nauseous mouthful. In Nicaragua there is a little frog " dressed in a bright livery " of red and blue " which does not conceal itself like most other species, but hops about during the daytime, and Mr. Belt says""* that as soon as he saw its happy sense of security, he felt sure that it was uneatable. " After several trials he succeeded in tempting a young duck to snatch up a young one, but it was instantly rejected ; and the duck " went about jerking its head, " as if trying to throw off some unpleasant taste." With respect to sexual differences of colour. Dr. Giinther does not know of any striking instance either with frogs or toads ; yet he can often distinguish the male from the female, by the tints of the former being a little more intense. Nor does he know of any striking difference in external structure between the sexes, excepting the prominences which become developed during the breeding-season on the front-legs of the male, by which he is enabled to hold the female.'*^ It is surprising that *^ Bell, * History of British Rep- sikrmmensis (Dr. Anderson, * Proc. tiles,' 2nd edit. 1849, pp. 146, 151. Zoolog. Soc.,' 1871, p. 204) has two *^ 'Zoology of the Voyage of the plate-like callosities on the thorax " Beagle," ' 1843. Bell, ibid. p. 49. and certain rugosities on the fingers, *** ' The Naturalist in Nicaragua,' which perhaps subserve the same end 1874, p. 321. as the above-mentioned prominences. *'' The male alone of the Bufo 350 The Descent of Man. Part II. these animals have not acquired more strongly-marked sexual characters ; for though cold-blooded their passions are strong. Dr. GUnther informs me that he has several times found an unfortunate female toad dead and smothered from having been so closely embraced by three or four males. Frogs have been observed by Professor Hoffman in Giessen fighting all day long during the breeding-season, and with so much violence, that one had its body ripped open. Frogs and toads offer one interesting sexual difference, namely, in the musical powers possessed by the males; but to speak of music, when applied to the discordant and overwhelming sounds emitted by male bull-frogs and some other species, seems, according to our taste, a singularly inappropriate expression. Nevertheless, certain frogs sing in a decidedly pleasing manner. Near Eio Janeiro I used often to sit in the evening to listen to a number of little Hylse, perched on blades of grass close to the water, which sent forth sweet chirping notes in harmony. The various sounds are emitted chiefly by the males during the breeding-season, as in the case of the croaking of our common frog.*^ In accordance with this fact the vocal organs of the males are more highly-develojDed than those of the females. In some genera the males alone are provided with sacs which open into the larynx.^^ For instance, in the edible frog {liana escultnta) " the sacs are peculiar to the males, and become, when filled " with air in the act of croaking, large globular bladders, stand- " ing out one on each side of the head, near the corners of the " mouth." The croak of the male is thus rendered exceedingly powerful ; whilst that of the female is only a slight groaning noise.^" In the several genera of the family the vocal organs differ considerably in structure, and their development in all cases may be attributed to sexual selection. Eeptiles. Chelonia. — Tortoises and turtles do not offer well-marked sexual differences. In some species, the tail of the male is longer than that of the female. In some, the plastron or lower surface of the shell of the male is slightly concave in relation to the back of - the female. The male of the mud-turtle of the United States (Chrysemys picta) has claws on its front-feet twice as long as those of the female ; and these are used when *8 Bell, 'History of British " J. Bishop, in 'Todd's Cyclop. Reptiles,' 1849, p. 93. of Anat. and Phvs.' vol. iv. p.'l503 *o Bell, ibid. p. 112-114. Chap. XII. Reptiles. 351 the sexes unite.^^ With the huge tortoise of the Galapagos Islands {Tedudo nigra) the males are said to grow to a larger size than the females: during the pairing-season, and at no other time, the male utters a hoarse bellowing noise, which can be heard at the distance of more than a hundred yards ; the female, on the other hand, never uses her voice.^^ With the Testudo degans of India, it is said " that the combats " of the males may be heard at some distance, from the noise " they produce in butting against each other." ^^ Crocodilia. — The sexes apparently do not differ in colour ; nor do I know that the males fight together, though this is pro- bable, for some kinds make a prodigious display before the females. Bartram^* describes the male alligator as striving to win the female by splashing and roaring in the midst of a lagoon, *' swollen to an extent ready to burst, with its " head and tail lifted up, he spins or twirls round on the " surface of the water, like an Indian chief rehearsing his feats of war." During the season of love, a musky odour is emitted by the submaxillary glands of the crocodile, and pervades their haunts.^^ Ophidia.—'Dr. Giinther informs me that the males are always smaller than the females, and generally have longer and slenderer tails ; but he knows of no other difference in external structure. In regard to colour, he can almost always distinguish the male from the female by his more strongly-pronounced tints ; thus the black zigzag band on the back of the male English viper is more distinctly defined than in the female. The difference is much plainer in the rattle-snakes of N. America, the male of which, as the keeper in the Zoological Gardens shewed me, can at once be distinguished from the female by having more lurid yellow about its whole body. In S. Africa the Bucephalus mpensis presents an analogous difference, for the female "is " never so fully variegated with yellow on the sides as the " male." ^^ The male of the Indian Dipsas ajnodon, on the other hand, is blackish-brown, with the belly partly black, whilst the female is reddish or yellowish-olive, with the belly either uniform yellowish or marbled with black. In the Tragops dispar of the same country, the male is bright green, and the 51 Mr. C. J. Maynard, 'The British India,' 1864, p. 7. American Naturalist,' Dec. 1869, p. ^* ' Travels through Carolina, 555. &c., 1791, p. 128. *2 See my < Journal of Researches ^^ Owen, * Anatomy of Verte- during the Voyage of the " Beagle," ' bratcs,' vol. i. 1866, p. 615. 1845, p. 384. 5« Sir Andrew Smith, ' Zoolo?. of 53 Dr. Giinther, 'Reptiles of S. Africa: Reptilia,' 1849, pi. xt 352 The Descent of Man. Part II. female bronze-coloured.^'' No doubt the colours of some snakes are protective, as shewn by the green tints of tree-snakes, and the various mottled shades of the species which live in sandy places ; but it is doubtful w^iether the colours of many kinds, for instance of the common English snake and viper, serve to conceal them; and this is still more doubtful with the many foreign species which are coloured with extreme elegance. The colours of certain species are very different in the adult and young states.^^ During the breeding-season the anal scent-glands of snakes are in active function f^ and so it is with the same glands in lizards, and as we have seen with the submaxillary glands of crocodiles. As the males of most animals search for the females, these odoriferous glands probably serve to excite or charm the female, rather than to guide her to the spot where the male may be found. Male snakes, though appearing so sluggish, are amorous ; for many have been observed crowding round the same female, and even round her dead body. They are not known to fight together from rivalry. Their intellectual powers are higher than might have been anticipated. In the Zoological Gardens they soon learn not to strike at the iron bar with which their cages are cleaned ; and Dr. Keen of Philadelphia informs me that some snakes which he kept, learned after four or five times to avoid a noose, with which they were at first easily caught. An excellent observer in Ceylon, Mr. E. Layard, saw '^^ a cobra thrust its head through a narrow hole and sw^allow a toad. " With this encumbrance he could not withdraw him- " self; finding this, he reluctantly disgorged the precious mor- " sel, which began to move off; this was too much for snake " philosophy to bear, and the toad was again seized, and again " was the snake, after violent efforts to escape, compelled to part " with its prey. This time, however, a lesson had been learnt, " and the toad w^as seized by one leg, withdrawn, and then " swallowed in triumph." The keeper in the Zoological Gardens is positive that certain snakes, for instance Crotalus and Python, distinguish him from all other persons. Cobras kej)t together in the same cage apparently feel some attachment towards each other.*^^ " Dr. A. Giinther, 'Reptiles of brates,' vol. i. 1866, p. 615. British India/ Ray Soc. 1864, pp. «<> ' Rambles in Cevlon.' in 'Anuals 304, 308. and Mag. of Nat. Hist.' 2nd series, 58 Dr. Stoliczka, ' Journal of vol. ix. 1852, p. 333. Asiatic Soc. of Bengal,' vol. xxxix. **! Dr. Giinther, * Reptiles of 1870, pp. 205, 211. British India,' 1864, p. 340. ^^ Owen, ' Anatomy of Verte- Chap. XII. Reptiles. 353 It does not, however, follow because snakes have some reasoning: power, strong passions and mutual affection, that they should likewise be endowed with sulhcient taste to admire brilliant colours in their partners, so as to lead to the adorn- ment of the species through sexual selection. Nevertheless, it is difficult to account in any other manner for the extreme beauty of certain species ; for instance, of the coral-snakes of S. America, which are of a rich red with black and yellow transverse bands. I well remember how much surprise I felt at the beauty of the first coral-snake which I saw gliding across a path in Brazil. Snakes coloured in this peculiar manner, as Mr. Wallace states on the authority of Dr. Giinther,"^ are found nowhere else in the world except in S. America, and here no less than four genera occur. One of these, Elaps, is venomous ; a second and widely-distinct genus is doubtfully venomous, and the two others are quite harmless. The species belonging to these distinct genera inhabit the same districts, and are so like each other, that no one "but a naturalist would distinguish the " harmless from the poisonous kinds." Hence, as Mr. Wallace l>elieves, the innocuous kinds have probably acquired their colours as a protection, on the principle of imitation ; for they would naturally be thought dangerous by their enemies. The cause, however, of the bright colours of the venomous Elaps remains to be explained, and this may j^erhaps be sexual selection. Snakes produce other sounds besides hissing. The deadly Ediis carinata has on its sides some oblique rows of scales of a peculiar structure with serrated edges ; and when this snake is excited, these scales are rubbed against each other, which pro- duces " a curious prolonged, almost hissing sound." ^^ With respect to the rattling of the rattle-snake, we have at last some definite information : for Professor Aughey states,^^ that on two occasions, being himself unseen, he watched from a little distance, a rattle-snake coiled up with head erect, which continued to rattle at short intervals for half an hour : and at last he saw another snake approach, and when they met they paired. Hence he is satisfied that one of the uses of the rattle is to bring the sexes together. Unfortunately he did not ascertain whether it was the male or the female which remained stationary and called for the other. But it by no means follows from the above foct that the rattle may not be of use to these snakes in other ways, as a warning to animals which would otherwise «2 ' Westminster Review,' July 1st, Soc' 1871, p. 196. 1867, p. 32. " i 'i'jjg American Naturalist,' '^^ Dr. Anderson, ' Proc. Zoolog. 1873, p. 85. 354 The Descent of Man. Part II. attack them. Nor can I quite disbelieve the several accounts which have appeared of their thus paralysing their prey with fear. Some other snakes also make a distinct noise by rapidly vibrating their tails against the surrounding stalks of plants ; and I have my- self heard this in the case of a Trigonocephalus in S. America. Zacertilia.— The males of some, probably of many kinds of lizards fight together from rivalry. Thus the arboreal Anolis cristatellus of S. America is extremely pugnacious : " During the " spring and early part of the summer, two adult males rarely " meet without a contest. On first seeing one another, they nod " their heads up and down three or four times, and at the same " time expanding the frill or pouch beneath the throat ; their " eyes glisten with rage, and after waving their tails from " side to side for a few seconds, as if to gather energy, they dart " at each other furiously, rolling over and over, and holding " firmly with their teeth. The conflict generally ends in one of " the combatants losing his tail, which is often devoured by the " victor." The male of this species is considerably larger than the female f^ and this, as far as Dr. Giinther has been able to ascertain, is the general rule with lizards of all kinds. The males alone of the Cyrtodactylus rahidus of the Andaman Islands possesses pre-anal pores ; and these pores judging from analogy probably serve to emit an odour.*'^ The sexes often differ greatly in various external characters. The male of the above-mentioned Anolis is furnished with a crest which runs along the back and tail, and can be erected at pleasure ; but of this crest the female does not exhibit a trace. In the Indian Cophotis ceylanica, the female has a dorsal crest, though much less developed than in the male ; and so it is, as Dr. Giinther informs me, with the females of many Iguanas, Chameleons, and other lizards. In some species, however, the crest is equally developed in both sexes, as in the Iguana tubercu- lata. In the genus Sitana, the males alone are furnished with a large throat-pouch (fig. 33), which can be folded up like a fan, and is coloured blue, black, and red ; but these splendid colours are exhibited only during the pairing-season. The female does not possess even a rudiment of this appendage. In the Anolis cristatellus, according to Mr. Austen, the throat pouch, which is bright red marbled with yellow, is present in the female, though in a rudimental condition. Again, in certain other lizards, both sexes are equally well provided with throat pouches. Here we " Mr. N. L. Austen kept these ^^ Stoliczka, ' Journal of Asiatic animals alive for a considerable Soc. of Bengal,' vol. xxxiv. 1870, p. time ; see ' Land and Water,' July 166. 1867, p. 9. Chap. XIT. Reptiles. 355 Fig. S"?. Sitana minor.* Male with tlie gular pouch expanded (from Giiuther's ' Reptiles of India '). see with species belonging to the same group, as in so many previous cases, the same character either confined to the males, or more largely developed in them than in the females, or again equally developed in both sexes. The little lizards of the genus Draco, which glide through the air on their rib- supported parachutes, and which in the beauty of their colours baffle description, are furnished with skinny appen- dages to the throat " like the wattles of gallinaceous birds." These become erected when the animal is excited. They occur in both sexes, but are best developed when the male arrives at maturity, at which age the middle appendage is sometimes twice as long as the head. Most of the species like- wise have a low crest running along the neck ; and this is much more developed in the full-grown males, than in the females or young males. *^^ A Chinese species is said to live in pairs during the spring ; " and if " one is caught, the other falls from *' the tree to the ground, and allows " itself to be captured with impu- ** nity," — I presume from despair.®^ There are other and much more remarkable differences between the sexes of certain lizards. The male of Ceratopliora aspera bears on the extremity of his snout an appendage half as long as the head. It is cylindrical, covered with scales, flexible, and apparently capable of erection: in the female it is quite rudimental. In a second species of the same genus a terminal scale forms a minute horn on the summit of the flexible appendage ; All the foregoing statements nificent work on the ' Reptiles of Fig. 34. Ceratophora Stoddartii Upper figure, male ; lower figure, female. and quotations, in regard to Cophotis, Sitana and Draco, as well as the following facts in regard to Cerato- phora and Chama)leon, are from Dr. Giinther himself, or from his mag- British India, 122, 130, 135. *^* Mr. Swinhoe Soc' 1870, p. 240. Ray Soc. 1864, pp. Proc. Zoo log. ,56 The Descent of Man. Part li. and in a tliird species (C. Stoddartii, fig. 34) the whole appen- dage is converted into a horn, which is usually of a white colour, but assumes a purplish tint when the animal is excited. In the adult male of this latter species the horn is half an inch in length, but it is of quite minute size in the female and in the yoang. These appendages, as Dr. Giinther has remarked to me, may be compared with the combs of gallinaceous birds, and apparently serve as ornaments. Fig. 35. Chama.'lcon bifurcus. Upper figure, male ; lower figure, female. In the genus Cliamaileon we come to the acme of difference between the sexes. The upper part of the skull of the male C. hifarcus (fig. 35), an inhabitant of Madagascar, is produced into two great, solid, bony projections, covered with scales like the rest of the head; and of this wonderful modification of structure the female exhibits only a rudiment. Again, in Chap. XII. Reptiles, 357 Charnodeon Owenii (fig. 3G), from the West Coast of Africa, the male bears on his snout and forehead three curious horns, of which the female has not a trace. These horns consist of an excrescence of bone covered with a smooth sheath, forming part of the general integu- ments of the body, so that they are identical in struc- ture with those of a bull, goat, or other sheath - horned ru- minant. Although the three horns differ so much in appearance from the two great pro- longations of the skull in C. h if lire us, we can hardly doubt that they serve the same general pur- pose in the economy of these two ani- mals. The first con- jecture, which will occur to every one, is that they are u^ed by the males for fighting together; and as these animals are very quarrelsome,*^* this is probably a correct view. Mr. T. W. Wood also informs me that he once watched two individuals of 0. pumilus, fighting violently on the branch of a tree ; they flung their heads about and tried to bite each other ; they then rested for a time, and afterwards continued their battle. With many lizards, the sexes dififer slightly in colour, the tints and stripes of the males being brighter and more distinctly defined, than in the females. This, for instance, is the case with the above Cophotis and with the Acnntlwdactylus caper, sis of S. Africa. Iif a Cordylus of the latter country, the male is either much redder or greener than the female. In the Indian Calotes nigrilahris there is a still greater diiFerence ; the lips also of the male are black, whilst those of the female are green. In our common little viviparous lizard (Zoofoca vivipara) "the " under side of the body and base of the tail in the male are " bright orange, spotted with black ; in the female these parts " are pale-greyish-green without spots." '° We have seen that «" Dr. Bucholz, ' Monatsberkht '» Bell, 'History of British K. Preuss. Akad.' Jtm. 1874, p. 78. Reptik-s,' 2nd edit. 1849, p. 40. Fig 36. Cl)ama?leon Owenii. Upper figure, male lower figure, female. 358 The Descent of Man. Part II. the males alone of Sitana possess a throat-pouch ; and this is splendidly tinted with blue, black, and red. In the Proctotretus tenuis of Chile the male alone is marked with spots of blue^ green, and coppery-red.'^^ In many cases the males retain the same colours throughout the year, but in others they become much brighter during the breeding-season ; I may give as an additional instance the Calotes maria, which at this season has a bright red head, the rest of the body being green.''^ Both sexes of many species are beautifully coloured exactly alike ; and there is no reason to suppose that such colours are protective. No doubt with the bright green kinds which live in the midst of vegetation, this colour serves to conceal them ; and in N, Patagonia I saw a lizard (Proctotretus multimaculatus) which, when frightened, flattened its body, closed its eyes, and then from its mottled tints was hardly distinguishable from the surrounding sand. But the bright colours with which so many lizards are ornamented, as well as their various curious appen- dages, were probably acquired by the males as an attraction, and then transmitted either to their male offspring alone, or to both sexes. Sexual selection, indeed, seems to have played almost as important a part with reptiles as with birds ; and the less conspicuous colours of the females in comparison with the males cannot be accounted for, as Mr. Wallace believes to be the case with birds, by the greater exposure of the females to danger during incubation. CHAPTER XIII. Secondary Sexual Chaeacters of Birds. Sexual differences — Law of battle — Special weapons — Vocal organs — Instrunneutal music — Love-antics and dances — Decorations, permanent and seasonal — Double and single annual moults — Display of ornaments by the males. Secondary sexual characters are more diversified and con- spicuous in birds, though not perhaps entailing riiore important changes of structure, than in any other class of animals. I shall, therefore, treat the subject at considerable length. Male birds sometimes, though rarely, possess special weapons for fighting ^^ For Proctotretus see * Zoology the Indian Calotes, see ' Reptiles of of the Voyage of the " Beagle :" British India,' by Dr. Giinther, p. Keptiles,' by Mr. Bell, p. 8. For 143. the Lizards of S. Africa, see ' Zoology ^^ Giinther in * Proc. Zoolog. Soc' of S. Africa: Reptiles,' by Sir 1870, p. 778, with a coloured Andrew Smith, pi. 25 and 39. For figure. Ch.u'. Xlir. Birds. 359 with each other. They charm the female by vocal or instru- mental music of the most varied kinds. They are ornamented by all sorts of combs, wattles, protuberances, horns, air-distended sacks, top-knots, naked shafts, plumes and lengthened feathers gi'acefully springing from all parts of the body. The beak and naked skin about the head, and the feathers are often gorgeously coloured. The males sometimes pay their court by dancing, or by fantastic antics performed either on the ground or in the air. In one instance, at least, the male emits a musky odour, which we may suppose serves to charm or excite the female ; for that excellent observer, Mr. Eamsay,^ says of the Australian musk- duck (^Biziura Jobata) that " the smell which the male emits " during the summer months is confined to that sex, and in " some individuals is retained throughout the year ; I have " never, even in the breeding-season, shot a female which had " any femell of musk." So powerful is this odour during the pairing-season, that it can be detected long before the bird can be seen.2 On the whole, birds appear to be the most aesthetic of all animals, excepting of course man, and they have nearly the same taste for the beautiful as we have. This is shewn by our enjoyment of the singing of birds, and by our women, both civilised and savage, decking their heads with borrowed plumes, and using gems which are hardly more brilliantly coloured than the naked skin and wattles of certain birds. In man, however, when cultivated, the sense of beauty is manifestly a far more complex feeling, and is associated with various intellectual ideas. Before treating of the sexual characters with which we are here more particularly concerned, I may just allude to certain differences between the sexes which apparently depend on differences in their habits of life; for such cases, though common in the lower, are rare in the higher classes. Two humming-birds belonging to the genus Eustephanus, which inhabit the island of Juan Fernandez, were long thought to be specifically distinct, but are now known, as Mr. Gould informs me, to be the male and female of the same species, and they diifer slightly in the form of the beak. In another genus of humming-birds (Grypus), the beak of the male is serrated along the margin and hooked at the extremity, thus differing much from that of the female. In the Neomorpha of New Zealand, there is, as we have seen, a still wider difference in the form of the beak in relation to the manner of feeding of the two sexes. Something of the same kind has been observed with the gold- • ' Ibis,' vol. iii. (new series) 1867, ^ Gould, ' Handbook to the Birds p. 414. of Australia,' 1805, vol. ii. p. 383. 360 The Descent of Ma?t. Yawt 11 finch {Cardudis eUgans), for I am assured by Mr. J. Jenrier Weir tliat the birdcatchers can distingnish the males by their slightly longer beaks. The flocks of males are often found feeding on the seeds of the teazle (Dipsacus), which they can reach with their elongated beaks, whilst the females more commonly feed on the seeds of the betony or Scrophularia. With a sKght difference of this kind as a foundation, we can see how the beaks of the two sexes might be made to differ greatly through natural selection. In some of the above cases, however, it is possible that the beaks of the males may have been first modified in relation to their contests with other males; and that this afterwards led to slightly changed habits of life. Laiv of Battle. — Almost all male birds are extremely pug- nacious, using their beaks, wings, and legs for fighting together. We see this every spring with our robins and sparrows. The smallest of all birds, namely the humming-bird, is one ♦of the most quarrelsome. Mr. Gosse^ describes a battle in which a pair seized hold of each other's beaks, and whirled round and round, till they almost fell to the gi-ound ; and M. Montes de Oca, in speaking of another genus of humming-bird, says that two males rarely meet without a fierce aerial encounter : when kept in cages " their fighting has mostly ended in the splitting of " the tongue of one of the two, which then surely dies from " being unable to feed."^ With W^aders, the males of the common water-hen {GalUnula cMoropus) "when jDairing, fight " violently for the females : they stand nearly upright in the " water and strike with their feet." Two were seen to be thus engaged for half an hour, until one got hold of the head of the other, which would have been killed, had not the observer interfered; the female all the time looking on as a quiet spec- tator.^ Mr. Blyth informs me that the males of an allied bird (Gallicrex cristatus) are a third larger than the females, and are so pugnacious during the breeding- season, that they are kept by the natives of Eastern Bengal for the sake of fighting. Various other birds are kept in India for the same purpose, for instance, the bulbuls (Pycnonotus haemorrhous) which " fight with great " spirit."*^ The polygamous ruff (Machttes puynax, fig. 37) is notorious for his extreme pugnacity ; and in the spring, the males, which are considerably larger than the females, congregate day after 3 Quoted by Mr. Gould, 'Intro- Ireland : Birds,' a'oI. ii. 1850, p. duction to the Trochilida?,' 1861, 327. p. 29. « Jerdon, 'Birds of India,' 1863, * Gould, ibid. p. 52. vol. ii. p. 96. 5 W. Thompson, 'Nat. Hist, of Chap. XIII. Law of Battle. 361 .day at a particular spot, wlierc tlie females propose to lay their eggs. The fowlers discover these spots by the turf being trampled somewhat bare. Here they fight very much like game- cocks, seizing each other with their beaks and striking with their wings. The great ruff of feathers round the neck is then erected, and according to Col. Montagu " sweeps the ground as " a shield to defend the more tender parts;" and this is the only 362 The Descent of Man, Pakt II. instance known to me in the case of birds, of any structure serving as a shield. The ruff of feathers, however, from its varied and rich colours probably serves in chief part as an orna- ment. Like most pugnacious birds, they seem always ready to fight, and when closely confined often kill each other ; but Montagu observed that their pugnacity becomes greater during the spring, when the long feathers on their necks are fully developed ; and at this period the least movement by any one bird provokes a genei-al battle.^ Of the pugnacity of web-footed birds, two instances will suffice : in Guiana " bloody fights occur " during the breeding-season between the males of the wild " musk-duck (CaiVi'na moschata') ; and where these fights have **^ occurred the river is covered for some distance with feathers." * Birds which seem ill-adapted for fighting engage in fierce con- flicts ; thus the stronger males of the pelican drive away the weaker ones, snapping with their huge beaks and giving heavy blows with their wings. Male snipe fight together, " tugging " and i^ushing each other with their bills in the most curious " manner imaginable." Some few birds are believed never to fight ; this is the case, according to Audubon, with one of the woodpeckers of the United States (Picks awra^ws), although "the " hens are followed by even half a dozen of their gay suitors." ^ The males of many birds are larger than the females, and this no doubt is the result of the advantage gained by the larger and stronger males over their rivals during many generations. The difference in size between the two sexes is carried to an extreme point in several Australian species ; thus the male musk-duck (Biziura) and the male Ciudoramphus cruralis (allied to our pipits) are by measurement actually twice as large as their respective females.^'' With many other birds the females are larger than the males ; and as formerly remarked, the explana- tion often given, namely, that the females have most of the work in feeding their young, will not suffice. In some few cases, as we shall hereafter see, the females apparently have acquired their greater size and strength for the sake of conquering other females and obtaining possession of the males. The males of many gallinaceous birds, especially of the poly- gamous kinds, are furnished with special weapons for fighting with their rivals, namely spurs, which can be used with fearful ^ Macgillivrar, * Hist. Brit. i. p. 191. For pelicans and snipes, Birds,' vol. iv. 1852, pp. 177-181. see vol. iii. pp. 138, 477. • Sir R. Schomburgk, in ' Journal '<> Gould, * Handbook of Birds of of R. Geograph. Soc' vol. xiii, 1843, Australia,' vol. i. p. 395; vol, ii. p. p. 31. 383 • 'Ornithological Biography,' vol. Chap. XII r. Law of Battle. 363 effect. It has been recorded by a trustworthy writer " that in Derbyshire a kite struck at a game-hen accompanied by her chickens, when the cock rushed to the rescue, and drove his spur right through the eye and skull of the aggressor. The spur was with difficulty drawn from the skull, and as the kite though dead retained his grasp, the two birds were firmly locked together; but the cock when disentangled was very little injured. The invincible courage of the game-cock is notorious : a gentleman who long ago witnessed the brutal scene, told me that a bird had both its legs broken by some accident in the cockpit, and the owner laid a wager that if the legs could be spliced so that the bird could stand upright, he would continue fighting. This was effected on the spot, and the bird fought with undaunted courage until he received his death- stroke. In Ceylon a clo'sely allied, wild species, the Gallus Stanley i, is known to fight desperately "in defence of his " seraglio," so that one of the combatants is frequently found dead.^^ An Indian partridge ( Ortygornis gularis), the male of which is furnished with strong and sharp spurs, is so quarrel- some, " that the scars of former fights disfigure the breast of " almost every bird you kill." ^^ The males of almost all gallinaceous birds, even those which are not furnished with spurs, engage during the breeding-season in fierce conflicts. The Capercailzie and Black-cock (Tetrao urogallus and T. tetrix), which are both polygamists, have regular appointed places, where during many weeks they congregate in numbers to fight together and to display their charms before the females. Dr. W. Kovalevsky informs me that in Eussia he has seen the snow all bloody on the arenas where the capercailzie have fought ; and the black-cocks " make the feathers fly in every " direction," when several " engage in a battle royal." The elder Brehm gives a curious account of the Balz, as the love- dances and love-songs of the Black-cock are called in Germaoy. The bird utters almost continuously the strangest noises : *' he " holds his tail up and spreads it out like a fan, he lifts up. his " head and neck with all the feathers erect, and stretches his " wings from the body. Then he takes a few jumps in different " directions, sometimes in a circle, and presses the under part of " his beak so hard against the ground that the chin feathers are " rubbed off. During these movements he beats his wings and " turns round and round. The more ardent he grows the more " lively he becomes, until at last the bird appears like a frantic '> Mr. Hewitt in the 'Poultry Nat. Hist.' vol. xiv. 1854, p. 63. Book by Tegetmeier,' 1866, p. 137. i^ Jerdon, 'Birds of India,' vol. -2 Layard, 'Annals and Mag. of iii. p. 574. 364 The Descent of Man. Part II. " creature." At snch times the black-cocks are so absorbed that they become almost blind and dea ', but less so than the caper- cailzie : hence bird after bird may be shot on the same spot, or even caught by the hand. After performing these antics the males begin to fight : and the same black-cock, in order to prove his strength over several antagonists, will visit in the course of one morning several Balz-jDlaces, which remain the same during successive years.^^ The peacock with his long train appears more Mke a dandy than a warrior, but he sometimes engages in fierce contests : the Kev. W. Darwin Fox informs me that at some little distance from Chester two peacocks became so excited whilst fighting, that they flew over the wiiole city, still engaged, until they alighted on the top of St. John's tower. The spur, in those gallinaceous bird's which are thus provided, is generally single ; but Polyplectron (see fig. 51, p. 397) has two or more on each leg; and one of the Blood- pheasants {Ithaginis cruentus) has been seen with five spurs. The spurs are generally confined to the male, being represented by mere knobs or rudi- ments in the female ; but the females of the Java peacock {Pavo muticus) and, as I am informed by IVIr. Blyth, of the small fire- backed pheasant (EujjJocamus erythroptliahnus) jDossess s^Durs. In Galloperdix it is usual for the males to have two spurs, and for the females to have only one on each leg.^^ Hence spurs may be considered as a masculine structure, which has been occasion- ally more or less transferred to the females. Like most other secondary sexual characters, the spurs are highly variable, both in number and development, in the same species. Various birds have spurs on their wings. But the Egyptian goose {ChenaJoj)ex cegyptiacus) has only " bare obtuse knobs," and these probably shew us the first steps by which true spurs have been developed in other species. In the spur-winged goose, Pledropterus gamhensis, the males have much larger spurs than the females; and they use them, as I am informed by Mr. Bartlett, in fighting together, so that, in this case, the wing-spui-s serve as sexual weapons ; but according to Livingstone, they are chiefly used in the defence of the young. The Palamedea (fig. 88) is armed with a pair of spurs on each wing ; and these are such formidable weapons, that a single blow has been known to drive a dog howling away. But it does not appear that the spurs in this case, or in that of some of the spur-winged rails, 1* Brehm, ' Illust. Thierleben,' Sweden,' &c., 1867, p. 79. 1867, B. iv. s. 351. Some of the ^* Jerdon, 'Birds of India: ou foregoing statements are taken from Ithaginis, vol. iii. p. 523 ; on Gallo- L. Lloyd, 'The Game Birds of perdix, p. 541. Chap. XIII. Law of Battle. 3^5 are larger in the male than in the female.^'^ In certain plovers, however, the wing-spurs must be considered as a sexual cha- Fig. 38. Palamedea cornuta (from Brehm), shewing the double wing-spurs, and the filament on the head. i« For the Egyptian goose, see p. 639. For Plectropterus, < Living- Macgillivray, ' British Birds,' vol. iv. stone's Travels,' p. 254. For Pala- ^66 The Descent of Man. Part II. racter. Thus in the male of our common peewit ( Vanellus cris- tatus) the tubercle on the shoulder of the wing becomes more prominent during the breeding-season, and the males fight together. In some species of Lobivanellus a similar tubercle becomes developed during the breeding-season " into a short "■ horny spur." In the Australian L. lobatus both sexes have spurs, but these are much larger in the males than in the females. In an allied bird, the Hoplopterusarmatus, the spurs do not increase in size during the breeding-season ; but these birds have been seen in Egypt to fight together, in the same manner as our peewits, by turning suddenly in the air and striking sideways at each other, sometimes with fatal results. Thus also they drive away other enemies.^^ The season of love is that of battle ; but the males of some birds, as of the game-fowl and ruff, and even the young males of the wild turkey and grouse,^* are ready to fight whenever they meet. The presence of the female is the teterrima belli causa. The Bengali baboos make the pretty little males of the amadavat ( tLstrtlda amandava) fight together by placing three small cages in a row, with a female in the middle ; after a little time the two males are turned loose, and immediately a desperate battle en- sues.^^ When many males congregate at the same appointed spot and fight together, as in the case of grouse and various other birds, they are generally attended by the females,^" which after- wards pair with the victorious combatants. But in some cases the pairing precedes instead of succeeding the combat : thus accord- ing to Audubon,^^ several males of the Virginian goat-sucker {Caprimulgus virginiamis) "court, in a highly entertaining " manner the female, and no sooner has she made her choice, " than her approved gives chase to all intruders, and drives medea, Brehm's ' Thievleben,' B. iv. 2<* Richardson on Tetrao umhellus s. 740. See also on this bird Azara, 'Fauna Bor, Amer. : Birds,' 1831, 'Voyages dans TAme'rique me'rid.' p. 343. L. Lloyd, 'Game Birds of torn. iv. 1809, pp. 179, 253. Sweden,' 1867, pp. 22, 79, on the ^'^ See, on our peewit, Mr. R. Carr capercailzie and black-cock. Brehm, in ' Land and Water,' Aug. 8th, however, asserts (' Thierleben,' &c., 1868, p. 46. In regard to Lobi- B. iv. s. 352) that in Germany the vanellus, see Jerdon's ' Birds of grey-hens do not generally attend India,' vol. iii. p. 647, and Gould's the Balzen of the black-cocks, but * Handbook of Birds of Australia,' this is an exception to the common vol. ii. p. 220. For the Holopterus, rule; possibly the hens may lie see Mr. Allen in the ' Ibis,' vol. v. hidden in the surrounding bushes, 1863, p. 156. as is known to be the case with the ** Audubon, ' Ornith. Biography,' grey-hens in Scandinavia, and with vol. ii. p. 492 ; vol. i. pp. 4-13. other species in N. America. 1* Mr. Blyth, ' Land and Water, "^^ ' Ornithological Biography, 1867, p. 212. vol. ii. p. 275. Chap. XIII. Law of Battle. 367 *' them beyond his dominions." Generally the males try to drive away oi* kill their rivals before they pair. It does not, however, appear that the females invariably prefer the victorious males. I have indeed been assured by Dr. W. Kovalevsky that the female capercailzie sometimes steals away with a young male who has not dared to enter the arena with the older cocks, in the same manner as occasionally happens with the does of the red-deer in Scotland. When two males contend in presence of a single female, the victor, no doubt, commonly gains his desire ; but some of these battles are caused by wandering males trying to distract the peace of an already mated pair.^ Even with the most pugnacious species it is probable that the pairing does not depend exclusively on the mere strength and courage of the male ; for such males are generally decorated with various ornaments, which often become more brilliant during the breeding-season, and which are sedulously displayed before the females. The males also endeavour to charm or excite their mates by love-notes^ songs, and antics ; and the courtship is, in many instances, a prolonged affair. Hence it is not probable that the females are indifferent to the charms of the opposite sex, or that they are invariably compelled to yield to the victorious males. It is more probable that the females are excited, either before or after the conflict, by certain males, and thus un- consciously prefer them. In the case of Tetrao umhellus, a good observer ^^ goes so far as to believe that the battles of the males " are all a sham, performed to show themselves to the greatest *' advantage before the admiring females who assemble around ; for *' I have never been able to find a maimed hero, and seldom more " than a broken feather." I shall have to recur to this subject, but I may here add that with the Tetrao cupido of the United States, about a score of males assemble at a particular spot, and strutting about, make the whole air resound with their extra- ordinary noises. At the first answer from a female the males begin to fight furiously, and the weaker give way; but then, according to Audubon, both the victors and vanquished search for the female, so that the females must either then exert a choice, or the battle must be renewed. So, again, with one of the field-starlings of the United States (Stumella ludoviciana) the males engage in fierce conflicts, " but at the sight of a female " they all fly after her, as if mad." ^^ " Brehm, 'Thierleben,' &e., B. 24 Audubon's ' Ornitholog. Bio- iv. 1867, p. 990. Audubon, ' Ornith. graphy ;' on Tetrao cupido, vol. ii. Biography,' vol. ii. p. 492. p. 492 ; on the Sturnus, vol. ii. p. 23 'Land and Water,' July 25th, 219. 1868, p. 14. 368 The Descent of Man. Part II. Vocal and instrumental music. — With birds the voice serves to express various emotions, such as distress, fear, anger, triumph, or mere happiness. It is apparently sometimes used to excite terror, as in the case of the hissing noise made by some nestling- birds. Audubon ^° relates that a mght-heron (Ardea nycticorax, Linn.) which he kept tame, used to hide itself when a cat approached, and then " suddenly start up uttering one of the " most frightful cries, apparently enjoying the cat's alarm and " flight." The common domestic cock clucks to the hen, and the hen to her chickens, when a dainty morsel is found. The hen, when she has laid an egg, " repeats the same note very often, " and concludes with the sixth above, which she holds for a longer time ; " ^^ and thus she expresses her joy. Some social birds apparently call to each other for aid ; and as they flit from tree to tree, the flock is kept together by chirp answering chirp. During the nocturnal migrations of geese and other water-fowl, sonorous clangs from the van may be heard in the darkness overhead, answered by clangs in the rear. Certain cries serve as danger signals, which, as the sportsman knows to his cost, are understood by the same S];)ecies and by others. The domestic cock crows, and the humming-bird chii'ps, in triumph over a defeated rival. The true song, however, of most birds and various strange cries are chiefly uttered during the breed- ing-season, and serve as a charm, or merely as a call-note, to the other sex. Naturalists are much divided with respect to the object of the singing of birds. Tew more careful observers ever lived than Montagu, and he maintained that the " males of song-birds and " of many others do not in general search for the female, but, " on the contrary, their business in the spring is to perch on some '• conspicuous spot, breathing out their full and amorous notes, " which, by instinct, the female knows, and repairs to the spot to ** choose her mate." ^^ Mr. Jenner Weir informs me that this is certainly the case with the nightingale. Bechstein, who kept birds during his whole life, asserts, "that the female canary " always chooses the best singer, and that in a state of nature " the female finch selects that male out of a hundred whose " notes please her most." ^^ There can be no doubt that birds closely attend to each other's song. Mr. Weir has told me ot 25 ' Ornithological Biograph.' vol. vogel,' 1840, s. 4. Mr. Harrisou V. p. 601. Weir likewise writes to me: — "I 2® The Hon. Daines Barrington, " am informed that the best singing ' Philosoph, Transact.' 1773, p. 252. " males generally get a mate first, 2^ ' Ornithological Dictionary,' " when they are bred in the same 1833, p. 475. "room." 2* ' Naturgeschichte der Stuben- Chap. XIII. Vocal Music. 369 the case of a bullfinch which had been iaught to pipe a German waltz, and who was so good a performer that he cost ten guineas ; when this bird was first introduced into a room where other birds were kept and he began to sing, all the others, con- sisting of about twenty linnets and canaries, ranged themselves on the nearest side of their cages, and listened with the greatest interest to the new performer. Many naturalists believe that the singing of birds is almost exclusively "the effect of rivalry " and emulation," and not for the sake of charming their mates. This was the opinion of Daines Barrington and White of Selborne, who both especially attended to this subjcct.^^ Bar- rington, however, admits that " superiority in song gives to " birds an amazing ascendancy over others, as is well known to " bird-catchers." It is certain that there is an intense degree of rivalry between the males in their singing. Bird-fanciers match their birds to see which will sing longest ; and I was told by Mr. Yarrel that a first-rate bird will sometimes sing till he drops down almost dead, or according to Bechstein,^" quite dead from rupturing a vessel in the lungs. Whatever the cause maybe, male birds, as I hear from Mr. Weir, often die suddenly during the season of song. That the habit of singing is sometimes quite ind-'pendent of love is clear, for a sterile, hybrid canary-bird has been de- scribed ^^ as singing whilst viewing itself in a mirror, and then dashing at its own image; it likewise attacked with fury a female canary, when put into the same cage. The jealousy excited by the act of singing is constantly taken advantage of by bird-catchers; a male, in good song, is hidden and protected, whilst a stuffed bird, surrounded by limed twigs, is exposed to view. In this manner, as Mr. Weir informs me, a man has in the course of a single day caught fifty, and in one instance seventy, male chaffinches. The power and inclination to sing differ so gTeatly with birds that although the price of an ordinary male chaffinch is only sixpence, Mr. Weir saw one bird for which the bird-catcher asked three pounds; the test of a really good singer being that it will continue to sing whilst the cage is swung round the owner's head. That male birds should sing from emulation as well as for charming the female, is not at all incompatible; and it might have been expected that these two habits would have concurred, like those of display and pugnacity. Some authors, however, " 'Philosophical Transactions,' ^^ ' Naturgesch. der Stubenvogel,' 1773, p. 263. White's 'Natural 1840, s. 252. History of Selborne,' 1825, vol. i. p. »' Mr. Bold, ' Zoologist,' 1843-44, 246. p. 659. 17 370 The Descent of Man. Part II. argue that the song of the -male cannot serve to charm the female, because the females of some few species, such as of the canary, robin, lark, and bnllfinch, especially when in a state of widow- hood, as Bechstein remarks, pour forth fairly melodious strains. In some of these cases the habit of singing may be in part attributed to the females having been highly fed and confined,^'* for this disturbs all the usual functions connected with tlie repro- duction of the siDecies. Many instances have already been given of the partial transference of secondary masculine characters to the female, so that it is not at all surprising that the females of some species should possess the power of song. It has also been argued, that the song of the male cannot serve as a charm, be- cause the males of certain species, for instance of the robin, sing during the autumn.^^ But nothing is more common than for animals to take pleasure in practising whatever instinct they follow at other times for some real good. How often do we see birds which fly easily, gliding and sailing through the air ob- viously for pleasure ? The cat plays with the captured mouse, and the cormorant with the captured fish. The weaver-bird (Ploceus), when confined in a cage, amuses itself by neatly weaving blades of grass between the wires of its cage. Birds which habitually fight during the breeding-season are generally ready to fight at all times; and the males of the capercailzie sometimes hold their Bahen or eks at the usual place of as- semblage during the autumn.^^ Hence it is not at all surprising that male birds should continue singing for their own amuse- ment after the season for courtship is over. As shewn in a previous chapter, singing is to a certain extent an art, and is much imj^roved by practice. Birds can, be taught various tunes, and even the unmelodious sparrow has learnt to sing like a linnet. They acquire the song of their foster parents,^^ and sometimes that of their neighbours.^'^ All the common songsters belong to the Order of Insessores, and their vocal organs are much more complex than those of most other birds ; j et it is a singular fact that some of the Insessores, such as ravens, cj ows, and magpies, possess the proper apparatus,^'' 32 D. Barrington, 'Phil. Transact.' Beohstein, ibid, s, 5. 1773, p. 262. Bechstein, 'Stuben- 3« Dureau de la Malle gives a vogel,' 1840, s. 4. curious instance ('Annales des Sc. 33 This is likewise the case with Nat.' 3rd series, Zoolog. torn. x. p. the water-ouzel, see Mr. Hepburn 118) of some wild blackbirds in his in the 'Zoologist,* 1845-1846, p. garden in Paris, which naturally 1068. learnt a rej-^ublican air from a caged 3^ L. Lloyd, 'Game Birds of bird. Sweden,' 1867, p. 25. :" Bishop, in ' Todd's Cyclop, of 3^ Barrington, ibid. p. 294, Aa^2 The Descent of Man. Part II. " Seo remarks to this efTect the 'Feelin? of Beauty on Animals/ by Mr. J. Shaw, in the among ' Athena>um,' Nov. 24th, 1866, p.681. Chap. XIII. Decoration. 383 at the commencement of this chapter, arc wonderfully diver- sified. The plumes on the front or back of the head consist of variously-shaped feathers, sometimes capable of erection or expansion, by which their beautiful colours are fully displayed. Elegant ear-tufts (see fig. 89, ante) are occasionally present. The head is sometimes covered with velvety down, as with the pheasant; or is naked and vividly coloured. The throat, also, is sometimes ornamented with a beard, wattles, or caruncles. Such appendages are generally brightly-coloured, and no doubt serve as ornaments, though not always ornamental in our eyes; for whilst the male is in the act of courting the female, they often swell and assume vivid tints, as in the male turkey. At such times the fleshy appendages about the head of the male Tragopan pheasant {Ceriorrcis Temminckii) swell into a large lappet on the throat and into two horns, one on each side of the splendid top-knot ; and these are then coloured of the most intense blue which I have ever beheld.^^ The African hornbill (Bucorax abyssinirus) inflates the scarlet bladder-like wattle on its neck, and with its wings drooping and tail expanded " makes quite a " grand appearance." ^^ ii^ven the iris of the eye is sometimes more brightly-coloured in the male than in the female; and this is frequently the case with the beak, for instance, in our common blackbird. In Buceros corrugatus, the whole beak and immense casque are coloured more conspicuously in the male than in the female ; and " the oblique grooves upon the sides of the lower " mandible are peculiar to the male sex.'"'^ The head, again, often supports fleshy appendages, filaments, and solid protuberances. These, if not common to both sexes, are always confined to the males. The solid protuberances have been described in detail by Dr. W. Marshall,*^^ who shews that they are formed either of cancellated bone coated with skin, or of dermal and other tissues. With mammals true horns are always supported on the frontal bones, but with birds various bones have been modified for this purpose ; and in species of the same group the protuberances may have cores of bone, or be quite destitute of them, with intermediate gradations connecting these two extremes. Hence, as Dr. Marshall justly remarks, variations of the most different kinds have served for the development through sexual selection of these ornamental appendages. Elongated feathers or plumes spring from almost ^2 See Dr. Murie's account with ^^ 'Land and Water,' 1868, p. coloured figures in ' Proc. Zoolog. 217, Soc' 1872, p. 730. ^^ 'Ueberdie Schiidelhocker,' &c., 63 Mr. Monteiro, 'Ibis,' vol. iv. ' Niederlandischeil Archiv fiir Zoo- 1862, p. 339. logic,' B. I. Heft. 2, 1872. 384 TJie Descent of Man. Part II. every part of the body. The feathers on the throat and breast are sometimes developed into beautiful ruffs and collars. The tail-feathers are frequently increased in length ; as we see in the tail-coverts of the peacock, and in the tail itself of the Argus pheasant. With the peacock even the bones of the tail have been modified to support the heavy tail-coverts.*'^ The body of the Argus is not larger than that of a fowl ; yet the length from the end of the beak to the extremity of the tail is no less than five feet three inches/^ and that of the beautifully ocellated secondary wing-feathers nearly three feet. In a small African night-jar (^Cosmetornis vexillarius) one of the primary wing- feathers, during the breeding -season, attains a length of twenty- six inches, whilst the bird itself is only ten inches in length. In another closely-allied genus of night-jars, the shafts of the elon- gated wing-feathers are naked, except at the extremity, where there is a disc.''^ Again, in another genus of night-jars, the tail-feathers are even still more prodigiously developed. In general the feathers of the tail are more often elongated than those of the wings, as any great elongation of the latter impedes flight. AYe thus see that in closely-allied birds ornaments of the same kind have been gained by the males through the development of widely different feathers. It is a curious fact that the feathers of species belonging to very distinct groups have been modified in almost exactly the same peculiar manner. Thus the wing-feathers in one of the above-mentioned night-jars are bare along the shaft, and ter- minate in a disc ; or are, as they are sometimes called, spoon or racket-shaped. Feathers of this kind occur in the tail of a motmot (Eiwiomota sujyerciliarifi), of a king-fisher, finch, hum- ming-bird, i^arrot, several Indian drongos (Dicrurus and Edolius, in one of which the disc stands vertically), and in the tail of certain birds of paradise. In these latter birds, similar feathers, beautifully ocellated, ornament the head, as is likewise the case with some gallinaceous birds. In an Indian bustard {Sypheotides auritus) the feathers forming the ear-tufts, which are about four inches in length, also terminate in discs.*'^ It is a most singular fact that the motmots, as Mr. Salvin has clearly shewn,''^" give to their tail feathers the racket-shape by biting off the barbs, and, further, that this continued mutilation has produced a certain amount of inherited effect. 66 Dr. W. Marshall,