bibliotheek r ; * THE DESCENT OF MAN, AND SELECTION IN RELATION TO SEX. BY THE SAME AUTHOR. ON THE ORIGIN OF SPECIES BY MEANS OF NATURAL SELECTION ; or. The Preservation op Favoured Races in the Struggle for Life; Fifth Edition ( Tenth Thousand), with Additions and Corrections. 1869. Murray. THE VARIATION OF ANIMALS AND PLANTS UNDER DOMESTICATION. In two vola. With Illustrations. 1868. Murray. ON THE VARIOUS CONTRIVANCES by which BRITISH AND FOREIGN ORCHIDS ARK FERTILISED BY INSECTS; and on the Goon Effects of Chossing. With numerous Woodcuts. Murray. A NATURALIST’S VOYAGE ROUND THE WORLD ; or, A Journal op Researches into the Natural History and Geology of the Countries visited during the voyage of H.M.S, * Bougie.' under the command of Captain FitzRoy, R.N. Eleventh Thousand. Murray. ON THE STRUCTURE AND DISTRIBUTION OF CORAL REEFS. Smith, Elder, & Co. GEOLOGICAL OBSERVATIONS ON VOLCANIC ISLANDS. Smith, Elder, & Co. GEOLOGICAL OBSERVATIONS ON SOUTH AMERICA. Smith, Elder, & Co. A MONOGRAPH OF THE CIRRIPEDIA. With numerous Illustrations. 2 vols. 8vo. Hardwick e. ON THE MOVEMENTS AND HABITS OF CLIMBING PLANTS. With Woodcuts. Williams & Norgate, LONDON: PRINTED BY WILLTAM CLOWES AND SONS, STAMFORD STREET, AND CHARING CROSS. Introduction Page 1-5 CONTENTS. PAET I. ON THE DESCENT OF MAN. CHAPTER I. The Evidence op 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, hones, reproductive organs, &c. The hearing of these three great classes of facts on the origin of man 9-33 CHAPTER II. Comparison of the Mental Powers of Man and tiie Lower Animals. The difference in mental power between the highest ape and the lowest savage, immense — Certain instincts in common The emotions — Curiosity — Imitation — Attention — Memory Ima- gination Reason — Progressive improvement Tools and weapons used by animals — Language feelf-consciousness Sense of beauty— Belief in God, spiritual agencies, superstitions 34-69 CHAPTER HI. Comparison of the Mental Powers of Man and the Lower Animals — continued. The moral sense Fundamental proposition— The qualities of social animals — Origin of sociability— Struggle between opposed in- stincts—Man a social animal— The more enduring social instincts VI CONTENTS OP VOL. 1. 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 judgment of the members of the same community on conduct — Trans- mission of moral tendencies — Summary .. .. Tage 7C-1C6 CHAPTEE IV. Off the Manner op Development of Man prom 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 — Ke- version — Correlated variation — Late 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 hecoming 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 107-157 CHAPTER V. On the Development of the Intellectual and Moral Faculties during Primeval and Civilised Times. The 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 158-184 CHAPTEE 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 — Similar small points of resemblance between man and the Quadrumana — Bank of man in the natural system — Birthplace and antiquity CONTENTS OF VOL. I. Y11 of man — Absence of fossil connecting-links — Lower stages in the genealogy of man, as inferred, firstly from his affinities and secondly from liis structure — Early androgynous condition of the Vertebrata — Conclusion .. .. : .. •• Page 185-213 CHAPTER VII. On the Races of Man. I he 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— Mono- genists and polygenists — 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 raco not descended from a single pair The ex- tinction of races — The formation of races — The effects of cross- ing— Slight influence of the direct action of the conditions of lile — - Slight or no influence of natural selection — Sexual selection 214-250 PART II. SEXUAL SELECTION. CHAPTER 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 inheritance — Causes why one sex and the young are not modified through sexual selection — Supplement on the proportional numbers ol the two sexes throughout the animal kingdom — On the limita- tation of the numbers of the two sexes through natural selection 253-320 Vlll CONTENTS OF YOL. I. CHAPTER IX. Secondary Sexual Characters in the Lower Classes of the Animal Kingdom. These characters absent in the lowest classes — Brilliant colours — Mollnsca — Annelids — Crustacea, secondary sexual characters strongly developed ; dimorphism ; colour ; characters not acquired before maturity — Spiders, sexual colours of ; stridulation by the males — Myriapoda Page 321-340 CHAPTER X. Secondary Sexual Characters of Insecst. Diversified structures possessed by the males for seizing the females — Differences betvyeen the sexes, of which the meaning is not understood — Difference in size between the sexes — Thysanura — Diptera — Hemiptera' — Ilomoptera, musical powers possessed by tho males alone — Orthoptera, musical instruments of the males, much diversified in structure ; pugnacity ; colours — Neuroptera, sexual differences in colour — Hymcnoptera, pug- nacity and colours— Coleoptera, colours ; furnished with great horns, apparently as an ornament; battles; stridulating organ.', generally common to both sexes 341-385 CHAPTER XI. Insects, continued. — Order Letidoi’TEUA. Courtship of butterflies — Battles — Ticking noise — Colours com- mon to both sexes, 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 — Per- ceptive powers of the Lepidoptera — Variability — Causes of the difference in colour between the males and females — Mimickry, female butterflies more brilliantly coloured than tho males — Bright colours of caterpillars — Summary and concluding re- marks on the secondary sexual characters of insects — Birds and insects compared 3bC-423 THE DESCENT OF MAN; AND ON SELECTION IN RELATION TO SEX. INTRODUCTION. The nature of the following work will he best under- stood 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 suffi- cient 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 implies that man must be included with other organic beings in any general conclusion respecting his manner of appear- ance on this earth. Now the case wears a wholly dif- ferent aspect. When a naturalist like Carl \ ogt ven- tures to say in his address as President of the National Institution of Geneva (I860), “ personae, en Europe “ au moins, n’ose plus soutenir la creation independante “ et de toutes pieces, des especes,” it is manifest that at least a large number of naturalists must admit that species are the modified descendants of other species ; VOL. i. B 2 INTRODUCTION. 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 other men, 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 appli- cable 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 deprived of the weighty argu- ments derived from the nature of the affinities which connect together whole groups of organisms — their geo- graphical distribution in past and present times, and their geological succession. The homological structure, embryological development, and rudimentary organs of a species, whether it be man or any other animal, to which our attention may be directed, remain to be con- sidered; 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 sup- port 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 INTRODUCTION. 3 his development ; and thirdly, the value of the differ- ('nces between the so-called races of man. As I shall confine myself to these points, it will not he necessary to describe in detail the differences between the several races — an enormous subject which has been fully dis- cussed in many valuable works. The high antiquity of umn has recently been demonstrated by the labours °f a host of eminent men, beginning with M. Boucher (1° Perthes ; and this is the indispensable 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 lnore than to allude to the amount of difference between unxn and the anthropomorphous apes ; for Prof. Huxley, la the opinion of most competent judges, has conclu- sively shewn that in every single 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 rn° interesting, 1 thought that they might interest others. It has often and confidently been asserted, that mans 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, wh° so positively assert that this or that problem will never he sol ved by science. The conclusion that man is the co-descendant with other species of some ancient, "or, and extinct form, is not in any degree new. La- ir 2 4 INTRODUCTION. marck long ago came to this conclusion, which has lately been maintained by several eminent naturalists and philosophers ; for instance by Wallace, Huxley, Lyell, Yogt, Lubbock, Buchner, Hollo, &c.,' and especially by Haokel. This last naturalist, besides his great work, ‘ Generelle Morphologic ’ (1866), has recently (1868, with a second edit, in 1S70), published his ‘Naturliche Schopfungsgeschiehte,’ 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. Hackel’s writings, I give his authority in the text, other statements I leave as they originally stood in my manu- script, 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 pro- bable that sexual selection has played an important part in differentiating the races of man; but in my 1 As the works of the first-named authors are so well known, I need not pivo the titles ; but as those of the latter are less well known in England, I will give them ‘ Seehs Vorlesungen uber die Darwin’- sche Thcorie:’ zweite Auflage, 1868, von Dr. L. Buchner; translated into French under the titlo * Conferences sur la Thermo Darwinienue,’ 1861). *Der Meusch, im Licit tu der Darwin’sehe Lehre,’ 1865, von Dr, F. Roll,, I will not attempt to give references to all the authors who have taken the same side of the question. Thus G. Canestrini has published (‘Annuario della Soe. d. Nat.,’ Modena, 1867, p. 81) a very curious paper on rudimentary characters, as bearing on the origin of man. Another work lias (1869) been published by Dr. Barrage Francesco, bearing in Italian the title of “ Man, made in the image of God, was also made in tiie image of the ape.” INTRODUCTION. 5 Origin of Species’ (first edition, p. 199) I contented lnyself by merely alluding to this belief. When I came to aPI>ly this view to man, I found it indispensable to treat the whole subject iu full detail.2 Consequently tire second part of the present work, treating of sexual election, has extended to an inordinate length, com- pared 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 by man dl|d the lower animals. My attention was called to this object many years ago by Sir Charles Bell’s admirable work. This illustrious anatomist maintains that man ls endowed with certain muscles solely for the sake expressing his emotions. As this view is obviously °Pposed to the belief that man is descended from some °ther and lower form, it was necessary for me to consider !t- I likewise wished to ascertain how far the emotions dre expressed in the same manner by the different races °f man. But owing to the length of the present work, have thought it better to reserve my essay, which is Partially completed, for separate publication. < q ) r°e Hackel ia the sole author who, since the publication of the th ^as discussed, in his various works, in a very able manner e subject of sexual selection, and has seen its full importance. Part I. THE descent or origin of man. - “ - : V - Part I.— THE DESCENT OF MAN. CHAPTER I. : j 1 The Evidence of the Descent of Man from some Lower Torh. Mature of the evidence hearing 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 hearing of these three great classes of facts on the origin of naan. 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 J°dily structure and in mental faculties; and if so, whether the variations are transmitted to his offspring ln accordance with the laws which prevail with the lower animals; such as that of the transmission of characters to the same age or sex. Again, are the variations the re- sult, 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 in- stance by correlation, the inherited effects of use and disuse, &c. ? Is man subject to similar malconformations, le ^sult of arrested development, of reduplication of parts, &c., and does he display in any of his anomalies reversion to some former and ancient type of structure ? nnght also naturally be enquired whether man, like S(J many other animals, has given rise to varieties and SU traces, differing but slightly from each other, or to 10 THE DESCENT OF MAN. Part I. 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, both in the first and succeeding genera- tions ? And so with many other points. Ihe 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 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 each other, 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 conve- niently 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 the two succeeding chapters the mental powers of man, in comparison with those of the lower animals, will be con- sidered. The Bodily Structure of Man.— It is notorious that man is constructed on the same general type or model with other mammals. 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 im- portant 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 ‘ (frossbirnwiudungen des Menschen,’ 18CS, s. 9U. Chap. i. HOMOLOGICAL STRUCTURE. 11 |u d'e brain of man has its analogy in that of the orang ; ut he adds that at no period of development do their JI'ains perfectly agree ; nor could this be expected, for otherwise their mental powers would have been the same. ' ulpian 2 remarks : “ Les differences reelles qui existent entre l’encephale de Fhomme et celui des singes supe- rieurs, sont bien minimes. II ne faut pas se faire ^’illusions a cet egard. L’homme est bien plus pres ‘ des singes anthropomorplies par les caracteres anato- ‘ miques de son cerveau que ceux-ci ne le sont non- soulement des autres mammiferes, inais memes de certains quadrumanes, des guenons ct des macaques.” 11 1 it would be superfluous here to give further details the correspondence between man and the higher '“animals in the structure of the brain and all other parts of the body. It may, however, be worth while to specify a few points, not directly or obviously connected with struc- tlxie> by which this correspondence or relationship is "oil shewn. Man is liable to receive from the lower animals, and lo communicate to them, certain diseases as hydro- P mbia, variola, the glanders, &c. ; and this fact proves ae dose similarity of their tissues and blood, both in '“mute structure and composition, far more plainly than f oes their comparison under the best microscope, or by 16 a'd of the best chemical analysis. Monkeys are 'able to many of the same non-contagious diseases as we j*le’ thus Rengger,3 who carefully observed for a long ^ 11116 t,le Celus Azarse, in its native land, found it liable 0 cata'T'h, with the usual symptoms, and which when , sur 'a Phys.’ 1866, p. 890, as quoted by M. Dally, ‘L’Ordre a f£matea et h Transformisme,' 1868, p. 29. - aturgesehiclite der Saugethiere von Paraguay,’ 1830, s. 50. 12 THE DESCENT OF MAN. Part I. often recurrent led to consumption. These monkeys suffered also from apoplexy, inflammation of the bowels, and cataract in the eye. The younger ones when shed- ding their milk-teeth often died from fever. Medicines produced the same effect on them as on us. Many kinds oi 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 ot lemons.4 An American monkey, an Ateles, alter 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 simi- larly their whole nervous system is affected. Man is infested with internal parasites, sometimes causing fatal effects, and is plagued by external para- sites, all of which belong to the same genera or families with those infesting other mammals. Man is subject like other mammals, birds, and even insects, to that mys- terious law, which causes certain normal processes, such as gestation, as well as the maturation and duration of various diseases, to follow lunar periods.5 His wounds - Brehm, ‘ Thiorlebcn,’ B. i. 1864, s. 75, 86. On the Ateles, s. 105 For other analogous statements, see s. 25, 107. “ Wltl1 respect to insects see Dr. Laycoek ‘ On a General Law of Vital Periodicity,’ British Association, 1842. Dr. Macculloch, ‘ Silli- (’hap. I. HOMOLOGICAL STKUCTUBE. 13 a*e rePaii'ed by the same process of healing ; and the s nmps left after the amputation of his limbs occa- sionally possess, especially during an early embryonic Period, some power of regeneration, as in the lowest ailimals.6 The whole process of that most important function, . le reproduction of the species, is strikingly the same 111 all mammals, from the first act of courtship by the rrrale 7 to the birth and nurturing of the young. Mon- Keys are born in almost as helpless a condition as our infants; and in certain genera the young differ " , f as much in appearance from the adults, as do our ( ‘ii^ren from their full-grown parents.8 It has been 'n-ged by some writers as an important distinction, that 'Vlt 1 num tlm young arriye at maturity at a much later ttSe than with any other animal : but if we look to the manltind which inhabit tropical countries the 1 eience is not great, for the orang is believed not to >e a( u't till the age of from ten to fifteen years.9 Man a American Journal of Science,’ vol. xvii. p. 305, lias seen dog suffering from tertian ague. At • 'ave giveu the evidence on this head iu my ‘Variation of ; 8 au Man’s Place in Nature,’ I8G3, p. 34. 14 THE DESCENT OF MAN. Part I. differs from woman in size, bodily strength, hairyness, &c., as well as in mind, in the same manner as do the two sexes of many mammals. It is, in short, scarcely possible to exaggerate the close correspondence in gene- ral structure, in the minute structure of the tissues, in chemical composition and in constitution, between man and the higher animals, especially the anthropomor- phous apes. Embryonic Development. — Man is developed from an ovule, about the 125th of an inch in diameter, which differs 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 verte- brate kingdom. At this period the arteries run in arch- like branches, as if to carry the blood to branchim 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 Yon Baer remarks, “ the wings and feet of birds, no less than the “ hands and feet of man, all arise from the same funda- “ mental form.” It is, says Prof. Huxley,10 “ 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 Inst assertion may appear to be, it is demonstrably “ true.” As some of my readers may never have seen a draw- ing of an embryo, I have given one of man and another of a dog, at about the same early stage of development, 10 * Man’s Place in Nature,’ 1863, p. 67. ClIAP. I. embryonic development. 15 % i. -L ' Per Rgnre human embryo, from Kcleer. from Iiischoft. Lower figure that of a (log. , c- HlndS^^n-iad 'o'fitata. cerebeHum, d- Rye. e- Rar. f- Flr»t visceral arch. g. Second visceral arch. H. Vertebral columns and muscles in process of development. i. Anterior ) K. Posterior j extremities. L. Tail or os coccyx. 10 THE DESCENT OF MAN. Part 1. carefully copied from two works of undoubted accu- racy.11 After tlie foregoing statements made by such high authorities, 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 like- wise resembles in various points of structure cer- tain low forms when adult. For instance, the heart at first exists as a simple pulsating vessel ; the excreta are voided through a cloaeal passage; and the os coccyx projects like a true tail, “ extending considerably “ beyond the rudimentary legs.” 12 In the embryos of al l air-breathing vertebrates, certain glands called the cor- pora Wolffiana, correspond with and act like the kidneys of mature fishes.13 Even at a later embryonic period, some striking resemblances between man and the lower animals may be observed. Bischoff says that the con- volutions of the brain in a human foetus at the end of the seventh month reach about the same stage of deve- lopment as in a baboon when adult.14 The great toe, as Prof. Owen remarks,15 “ which forms the fulcrum when “ standing or walking, is perhaps the most characteristic 11 The human embryo (upper fig.) is from Ecker, ‘leones Phys.,’ 1851-1859, tab. xxx. fig. 2. This embryo was ten lines in length, so that the drawing is much magnified. The embryo of the dog is from Bischoff, ‘ Entwieklungsgeschiohte dcs Hundc-Eies,’ 1845, tab. xi. fig. 42 B. This drawing is five times magnified, the embryo being 25 days old. The internal viscera have been omitted, and the uterine appen- dages in both drawings removed. I was directed to these figures by Prof. Huxley, from whose work, ‘ Man's Place in Nature,’ the idea of giving them was taken, Hacked has also given analogous drawings in his ‘ Scliopfutigsgeschichte.’ 12 Prof. Wyman in ‘Proc. of American Acad, of Sciences,’ vol. iv. 1860, p. 17. 13 Owen, ‘ Anatomy of Vertebrates,’ vol. i. p. 533. 14 ‘Die Grosshirnwindungen des Menschen,’ 1868, s. 95. 15 ‘Anatomy of Vertebrates,’ vol. ii. p. 553. Chap. j_ RUDIMENTS. 17 ^ peculiarity in the human structure;” but in an em- «, 1°’ about an inch in length, Prof. Wyman 16 found <« . at tllc gi'eat toe was shorter than the others, and, (( instead of being parallel to them, projected at an „ ^ e h'mn the side of the foot, thus corresponding „ "ltb ii'c permanent condition of this part in the quadrumana.” I will conclude with a quotation from ( ';'xley,17 who after asking, does man originate in a '/ ei'eut way from a dog, bird, frog or fish? says, “ the t( 'I'Piy is not doubtful for a moment; without question, (( 16 mode of origin and the early stages of the develop- (i !Uent °f man are identical with those of the animals „ lllJVUediat(‘ly below him in the scale : without a doubt <( 111 ^'ese respects, he is far nearer to apes, than the apes are to the dog.” Rudiments. — This subject, though not intrinsically sr JlliPortant than the two last, will for several rea- ,e bere treated with more fullness.16 Not one of gQle gi'er animals can be named which does not bear ^Jue ptnt jn a rudimentary condition ; and man forms be ?X<*eP^i°n to the rule. Eudimentary organs must in C S^lnSuished from those that are nascent ; though areS°me cuse!S the distinction is not easy. The former n , eitber absolutely useless, such as the mammae of wk' a 21 aild not a few muscles, are regularly present in some of the lower ani- red ^ C^n occasiouaUy be detected in man in a greatly .)()JlCe cpndition. Every one must have noticed the of m1 • cb nrany animals, especially horses, possess jjV 0Vlng or twitching their skin ; and this is effected in an^ i'aunb'ubls carnosus. Remnants of this muscle bodin ! state are found in various parts of our ’ r or instance, on the forehead, by which the devel 'JU S| U'e ra'se belongs to this system. Prof, inform^ ° hdinljurgh, has occasionally detected, as he tion ■ S Uie’ UlUscular fasciculi in five different situa- whichname ^ 'n ^1C axdla‘) near the scapulae, &c., all of He h' IQ,jSt 'J0 reterred to the system of the panniculus. Kalis T a S° sbe" n 22 ^at the musculus sternalis or ster- dljcio ni/orum’ which is not an extension of the rectus minalis, but is closely allied to the panniculus, oc- 20 < ~tr . PP. 317 and 39 7 of and Plants under Domestication,’ vol. ii. 21 For install . m also ‘ 0rl&111 of Species,’ Stir edit. p. 535. Zoolog. 1S52 t 6 .tUohftrd (‘ Aunales des Sciences Nat.’ 3rd series, 116 calls the’“ l?' P' deseribcs alul figures rudiments of wliat " ‘“fiuiment neti,n 6 P*lieux tle ,a main •” which he says is sometimes generally quite / Another muscle, called “le tibial posterieur,” is ft0,re or less rudim, m the lland’ but aPPears from time to time in a Prof, w t ‘ary c0111111'""- uiiur, ‘Proe. Xtoyal Soc. Edinburgh,’ 1866-67, p. 65. 20 THE DESCENT OF MAN. Tart I. curred in the proportion of about 3 per cent, in upwards of 600 bodies : lie 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 superficial 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 a 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 all his three chil- dren 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 persistently an absolutely useless faculty may be transmitted. The extrinsic muscles which serve to move the whole external ear, and the intrinsic muscles which move the different parts, all of which belong to the system of the panniculus, are in a rudimentary condition in man ; they are also variable in development, or at least in function. I have seen one man who could draw his ears for- wards, and another wdio could draw them backwards;23 23 Canestrini quotes Hyrt. (‘ Annuario della Soc. dei Naturalisti,’ Modena, 1867, p. 97) to the same effect. Chap. i. RUDIMENTS. 21 b\i^r°m w^la^ orie these persons told me, it is pro- a J e that most ot us by often touching our ears and Us Erecting our attention towards them, could by repeated trials recover some power of movement. The acuity of erecting the ears and of directing them to I 'ncrent points of the compass, is no doubt of the ughest service to many animals, as they thus perceive le l)0*ut of danger; but I have never heard of a man '' l0 Possessed the least power of erecting his ears, — le one movement which might be of use to him. The W lc^e external shell of the ear may be considered a rudiment, together with the various folds and promi- nences (helix and anti-helix, tragus and anti-tragus, &c.) ' ich in the lower animals strengthen and support the ^ar "hen erect, without adding much to its weight. ^ orue authors, however, suppose that the cartilage of the serves to transmit vibrations to the acoustic k'erve > but Mr. Toynbee,'44 after collecting all the 'flown evidence on this head, concludes that the exter- 1 SlePl 48 °f uo distinct use. The ears of the chim- panzee and orang are curiously like those of man, and I th ,dS,Sured by the keepers in the Zoological Gardens tjjdt ^bese animals never move or erect them ; so that ^ ^ are m an equally rudimentary condition, as far as asUctl0Q 48 concerned, as in man. Why these animals, We 1 as the progenitors of man, should have lost the wei of erecting their ears we cannot say. Jt may be, 1 b am not quite satisfied with this view, that owing hut r'"U' ai'bQ1'(-al habits and great strength they were Per' V 6 e nictitating membrane, or third eyelid, with its nccessory muscles and other structures, is especially VVe developed in birds, and is ol much functional im- portance to them, as it can be rapidly drawn across the " o e eye-ball. It is found in some reptiles and arnphi- and in certain fishes, as in sharks. It is fairly e developed in the two lower divisions of the mam- noi ian series, namely, in the monotremata and marsu- 1 la s, and in some few of the higher mammals, as in the 'a rus‘ '’Of in man, the quadrumana, and most other lammals, it exists, as is admitted by all anatomists, as a rue re rudiment, called the semilunar fold.20 the 16 S6nSe SIII
with tlie terminal part consisting of a flat- solid expansion. In the orang this appendage in man it arises from the and is commonly from four being only about the third - . — — Not only is it useless, but sometimes the cause of death, of which fact I hard !atdy ^lear belonging to the Reindeer period ; whilst M. jeguay, in a sort of dolmen at Argenteuil, observed [( ^venty-five per cent, to be perforated ; and M. Pruner- <( . °y found twenty-six per cent, in the same condition (1 lri bones from Y aureal. N or should it be left unno- „ tleec^ that M. Pruncr-Bcy states that this condition is common in Guanche skeletons.” The fact that ancient aees> hr this and several other cases, more frequently present structures which resemble those of the lower ammals than do the modern races, is interesting. One j1Ca cause seems to be that ancient races stand some- j lftt nearer than modern races in the long lino of, * to fbeir remote animal-like progenitors. ■ • iC 08 coccyx ™ man, though functionless as a tail, mun y represents this part in other vertebrate animals. an early embryonic period it is free, and, as we have j^1'5 P10iects beyond the lower extremities. In certain aie and anomalous cases it has been known, according ^ snlore Geoftroy St.-Hilaire and others,40 to form a external rudiment of a tail. The os coccyx is r. ’ nsually including only four vertebrae : and these ° m a ru t u the Nature of Limbs,’ 1849, p. 114. 30 THE DESCENT OF MAN. Part I. described by Theile as a rudimentary repetition of the extensor of the tail, which is so largely developed in many mammals. The spinal cord in man extends only as far down- wards as the last dorsal or first lumbar vertebra; but a thread-like structure (the filum terminate) 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 j)ia mater, or vascular investing membrane. Even in this case the os coccyx may be said to possess a vestige of so im- portant a structure as the spinal cord, though no longer enclosed within a bony canal. The following fact, for which I am also indebted to Prof. Turner, shews how closely the os coccyx corresponds 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, though not at the extre- mity, a similarly convoluted body. The reproductive system oilers various rudimentary structures ; but these differ in one important respect from the foregoing cases. We are not here concerned with a vestige of a part which does not belong to the species in an efficient state ; but with a part which is always present and efficient in the one sex, beinn represented in the other by a mere rudiment. Never- theless, the occurrence of such rudiments is as diffi- cult 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 CilAP, I. THE DESCENT OE MAN. 31 ha ei^ance > namely, on parts acquired by one sex }Xen Partia% transmitted to the other. Here is '! 11.0nlJr give s°me instances of such rudiments. It clud"3 ^novvn that in the males of all mammals, in- S( . ln§ nmn, rudimentary mammas exist. These in vi'lDi lnstances have become well developed, and have tit • a cof,ious suPP]y milk. Their essential iden- y nr the two sexes is likewise shewn by their occa- atf sympathctic enlargement in both during an ha-sl °f the measles. The vesicula prostatica, which een observed in many male mammals, is now uni- ^eisally acknowledged to be the liomologuc of the jgftla e nterus, together with the connected passage. It J^-ble to read Leuckart’s able description of this 0f\an> ant* bis reasoning, without admitting the justness tho ^ concbision. This is especially clear in the case of cates DJam“als in which the true female uterus bifur- h>it'ivr 5 01 JU tb*3 males of these the vesicula likewise bel 1CatGS'42 ^°me additional rudimentary structures u. n>=lno to the reproductive system might here have een adduced.43 e. bearing of the three great classes of facts now full ^ 1S UnniIstakeable. But it would be superfluous here in I le*'aIatulrtte the line of argument given in detail of the °b Species.’ The homological construction inteir "i'l0^e frame in the members of the same class is pr S'ole, if we admit their descent from a common to togetbe.r with their subsequent adaptation larit 1Ve,rsb‘ec^ conditions. On any other view the simi- 3" o pattern between the hand of a man or monkey, hx la«rtt!Srt’rl“TT,?dd’s,‘ Cyclop. of Aliat:’ 1849'52> iv- [>. Min. "1 ttany other i ' ' this • - i r - — — • - 80 many other ru p 13 0n,y from tbree to six lines in length, but, like 88 'a other char (,!mentary parts, it is variable in development as well See ■ a" (176, 7QQtlds subject, Owen, ‘Anatomy of Vertebrates,’ vol. iii. pp. 32 THE DESCENT OF MAN. Fart I- 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, on the principle of varia- tions 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 embryo of a man, dog, seal, bat, reptile, &c., can at first hardly be distinguished from each other. In order to understand the existeirce 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 they became greatly reduced, either from simple disuse, or through the natural selection of those indivi- duals which were least encumbered with a superfluous part, aided by the other means previously indicated. 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 struc- ture 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 de- rived from their affinities or classification, their geo- graphical distribution and geological 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 Cijip j THE DESCENT OF MAN. 33 ls conclusion. But the time will before long come ^ len it will be thought wonderful, that naturalists, who "ere Well acquainted with the comparative structure j n< development of man and other mammals, should d'e believed that each was the work of a separate act of creation. D VOT,. x. 34 THE DESCENT OF MAN. Part t. CHAPTER II. Comparison of the Mental Powers of Man and the Lower Animals. The difference in mental power between the highest ape and the lowest savage, immense — Certain instincts in common — The emotions — Curiosity — Imitation — Attention — Memory — Ima- gination — Reason — Progressive improvement — Tools and weapons used by animals — Language — Self-consciousness — Sense of beauty — Belief in God, spiritual agencies, superstitions. We have seen in the last chapter that man bears in his bodily structure clear traces of his descent from some lower form ; but it may be urged that, as man differs so greatly in his mental power from all other animals, there must be some error in this conclusion. No doubt the difference in this respect is enormous, even if we com- pare the mind of one of the lowest savages, who has no words to express any number higher than four, and who uses no abstract terms for the commonest objects or affections,1 with that of the most highly organised ape. The difference would, no doubt, still remain immense, even if one of the higher apes had been improved or civilised as much as a dog has been in comparison with its 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 hoard 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 1 See the evidence on those points, as given by Lubbock, 1 Prehistoric Times,’ p. 354, &c. 'Ciup. jjr MENTAL POWEES. 35 01 game being excepting man liacl possessed any mental power, or if his powers had been of a wholly different Mature from those of the lower animals, then we should jUfVer have been able to convince ourselves that our "&b faculties had been gradually developed. But it on be clearly shewn that there is no fundamental f ifference of this kind. We must also admit that lore is a much wider interval in mental power be- eeu one of the lowest fishes, as a lamprey or lancelct, °no of the higher apes, than between an ape and fan; yet this immense interval is filled up by ntimber- Iess gradations. Nor is , - — the difference slight in moral disposition etween a barbarian, such as the man described by the ? navigator Byron, who dashed his child on the rocks p1 dropping a basket of sea-urchins, and a Howard or arkson ; and in intellect, between a savage who does Trf U8e an^ akstraet terms, and a Newton or Shakspeare. ^ 1 ferences of this kind between the highest men of the J1ghest races and the lowest savages, are connected by 10 ®uest gradations. Therefore it is possible that they nnght pass and be developed into each other. . Ny object in this chapter is solely to shew that there jS. 110 fundamental difference between man and the b- ier mammals in their mental faculties. Each divi- ■ *°n ot the subject might have been extended into a ^ate essay, but must here be treated briefly. As ^ classification of the mental powers has been univer- “ y accepted, I shall arrange my remarks in the order p convenient for my purpose ; and will select those tlm S fi&ve most struck me, with the hope that Produce some effect on the reader, hav + 1 r?sfiect to animals very low in the scale, I shall lion6 1° ^-'*e some additional facts under Sexual Selec- ’ s 10wing that their mental powers are higher than d 2 3G THE DESCENT OF MAN. Part P. might have been expected. The variability of the facul- ties in the individuals of the same species is an im- portant point for ns, 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 differ greatly in every mental characteristic. In what manner the mental powers were first developed in the lowest organisms, is as hopeless an enquiry as how life first originated. These are problems for the distant future, if they are ever to be solved by man. As man possesses the same senses with 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 power possessed by the latter of sucking, and so forth. But man, perhaps, has somewhat fewer instincts than those possessed by the animals which come next to him in the scries. The orang in the Eastern islands, and the chimpanzee in Africa, build platforms on which they sleep ; and, as both species follow the same habit, it might he argued that this w as 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 wc 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 turned out in the spring, often eat poisonous herbs, which they afterwards avoid, wo 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 MENTAL POWERS. ■7 C"AP. II. au instinctive clread of serpents, and probably of other dangerous animals. . i he fewness and the comparative simplicity of the '"stincts in the higher animals are remarkable in eon- trast with those of the lower animals. Cuvier main- tained that instinct and intelligence stand in an inverse oitio to each other; and some have thought that the intellectual faculties of the higher animals have been fdadually developed from their instincts. .But Pouch et, 111 an interesting essay,3 has shewn that no such inverse latio really exists. Those insects which possess the most n'onderful instincts are certainly the most intelligent. ' u the vertebrate series, the least intelligent members, finely fishes and amphibians, do not possess complex instincts ; and amongst mammals the animal most re- f-nirkable for its instincts, namely the beaver, is highly mtelligent, as will be admitted by every one who has lea Mr from wishing to deny that instinctive actions illuy lose their fixed and untaught character, and he ■j -'placed by others performed by the aid of the free will, j ,n ^he other hand, some intelligent actions — as when ,|Jds on oceanic islands first learn to avoid man — after 3, 97,-. ^llstiuot eliez les Insectes.’ ‘Revue des Deux Mondes,’ Feb. P- 690. 4 ‘ T)16 American Beaver and Ms Works,’ 1868. le Principles of Psychology/ '2nd edit. 1870, pp. 416-443 38 THE DESCENT OF MAN. Pari I. being performed during many generations, become con- verted into instincts and are inherited. They may then bo said to be degraded in character, for they are no longer performed through reason or from experience. But the greater number of the more complex instincts appear to have been gained in a wholly different man- ner, through the natural selection of variations of simpler instinctive actions. Such variations appear to arise from the same unknown causes acting on the cerebral organ- isation, which induce slight variations or individual dif- ferences in other parts of the body ; and these variations, owing to our ignorance, are often said to arise sponta- neously. 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 offspring to inherit the effects of experience and of modified habits. Although a high degree of intelligence is certainly compatible with the existence of complex instincts, as we see in the insects just named and in the beaver, it is not improbable that they may to a certain extent inter- fere with each other’s development. Little is known about the functions ol the brain, but we can perceive that as the intellectual powers become highly developed, the various parts of the brain must be connected by the most intricate channels of intercommunication ; and as a consequence each separate part would perhaps tend to become less well fitted to answer in a definite and uni- form, that is instinctive, manner to particular sensations or associations. 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 com- pare their actions founded on the memory of past events, on foresight, reason, and imagination, with MENTAL POWEES. 3!) ttij «*. II. ■'xactly similar actions instinctively performed by the °'Ver animals ; in this latter case the capacity of Informing such actions having been gained, step by s^ePi through the variability of the mental organs and Natural selection, without any conscious intelligence on 16 part of the animal during each successive genera- 10u- No doubt, as Mr. Wallace has argued,6 much of kl° intelligent work done by man is due to imitation and to reason ; but there is this great difference between Us_ actions and many of those performed by the lower aDimals, namely, that man cannot, on his first trial, !nake, for instance, a stone hatchet or a canoe, through ns power of imitation. He has to learn his work by Practice ; a beaver, on the other hand, can make its dam I*1 canal, and a bird its nest, as well, or nearly as well, e first time it tries, as when old and experienced. -i° return to our immediate subject: the lower animals, like man, manifestly feel pleasure and pain, happiness and misery. Happiness is never better exhi- bit'd than by young animals, such as puppies, kittens, Ev 's> &c., when playing together, like our own children. ,Veu insects play together, as has been described by dt excellent observer, P. Huber,0 who saw ants chasing aild pretending to bite each othei-, like so many puppies. Ihe fact that the lower animals are excited by the same emotions as ourselves is so well established, that J 'nil not he necessary to weary the reader by many c et?dls. Terror acts in the same manner on them as on causing the muscles to tremble, the heart to pal- pitate, the sphincters to be relaxed, and the hair to and on end. Suspicion, the offspring of fear, is emi- Jaently characteristic of most wild animals. Courage 0 .^Mmtions to the Theory of Natural Selection,’ 1870, p. 212. •Keoherches snr les Mceurs des Fourmis,’ 1810, p. 173. 40 THE DESCENT OF MAN. Part I. 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-tempered ; and these qualities are certainly inherited. Every oue knows liow liable animals arc to furious rage, and how plainly they show it. Many anecdotes, probably true, have been published on the long-delayed and artful revenge of various animals. The accurate Eengger and Erehm7 state that the American and African monkeys which they kept tame, certainly revenged themselves, llie love of a dog tor his master is notorious; in the agony ol death ho has been known to caress bis master, and every one has heard of the dog suffering under vivisection, who licked the hand of the operator; this man, unless ho had a heart ol stone, must have felt remorse to the last hour of his life. As Whewell8 has remarked, “ 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 maternal affection exhibited 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 llylobates washing the faces of her young ones iu a stream. So intense is the grief of female monkeys for the loss of their young, that it invariably caused the death of cer- tain kinds kept under confinement by Brehm in N. ' All tlie following statements, given on the authority of those two naturalists, arc taken from Rengger’s ‘ Naturges. tier Saugetkiere vou Paraguay,’ 1830, s. 41-57, and from Brehm’s ‘ Thierleben ’ B i s. 10-87. 8 ‘ Bridgewater Treatise,’ p. 203. '■'•Ur. u. MENTAL POWERS. 41 ■ hica. Orphan- monkeys were always adopted and °ai'efully guarded by the other monkeys, both males a,1d females. One female baboon had so capacious a "'art that she not only adopted young monkeys of Ie|' species, but stole young dogs and cats, which she “’"tinually carried about. Her kindness, however, did "'f go so far as to share her food with her adopted ""spring, at which Brehm was surprised, as his monkeys 1 wa.vs divided everything quite fairly with their own •UUng ones. An adopted kitten scratched the above- mentioned affectionate baboon, who certainly had a intellect, for she was much astonished at being hatched, and immediately examined the kitten’s feet, y" without more ado bit off the claws. In the /0o ogical Gardens, 1 heard from the keeper that 111 old baboon (G. cliacma ) had adopted a Rhesus °nkey . )Jut wpen a young drill and mandrill were d, ed in ppe ca„e sj10 seeined to perceive that these monke P C:S’ tor she at once rejected the Rhesus and adopted dp, 1 tfienr. The young Rhesus, as I saw, was greatly ' ""tented at being thus rejected, and it would, like tiy Ve^8> tllough distinct species, were her nearer rela- C di; flighty child, annoy and attack the young drill and ^aiidrill whenever it could do so with safety; this ^r1'1 Uct exciting great indignation in the old baboon. 011 will also, according to Brehm, detcud their vaster when attacked by any" one, as well as dogs to I 0111 they are attached, from the attacks ot other tob5,‘, . Iiut we here trench on the subject of sympathy, fool-11 ^ s*iah- recur. Some of Brelnu’s monkeys lv Inuch delight in teasing, in various ingenious \YQjVo O ■ ’ a certain old doo- whom they disliked, as well as "ther animals. tin* ]JS- ^le 111 ore complex emotions are common to ugher animals and ourselves. Every one has seen 42 THE DESCENT OF MAN. Part I- 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. This shews that animals not only love, but have the desire to be loved. Animals manifestly feel emulation. They love approbation 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 little 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 when 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. 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 Rcngger, with monkeys. All animals feel Wonder, and many exhibit Curiosity. They sometimes suffer from tin's latter quality, as when the hunter plays antics and thus attracts them; I have witnessed this with deer, 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 towards snakes ; but their curiosity was so great that they could not desist from occasionally satiating 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 MENTAL POWERS. 43 Cha: r. H. ^0l ed-up snake into the monkey -house at the Zoo- gieal Gardens, and the excitement thus caused was 2?e °f the most curious spectacles which I ever beheld. -fhree species of Oercopithecus were the most alarmed ; . y dashed about their cages and uttered sharp signal- Cries of danger, which were understood by the other lll0nkeys. A few young monkeys and one old Anubis babi '°°u alone took no notice of the snake. I then | aced the stuffed specimen on the ground in one of oe larger compartments. After a time all the monkeys ‘-'Elected round it in a large circle, and staring in- ently, presented a most ludicrous appearance. They became extremely nervous ; so that when a wooden ball, 1 1 1 which they were familiar as a plaything, was acci- Moved in the straw, under which it was partly i 1(. c en> they all instantly started away. These monkeys e laved very differently when a dead fish, a mouse, and mmo other new objects were placed in their cages ; for °ugh at first frightened, they soon approached, handled Uf examined them. I then placed a live snake in a ^ aPer bag, w ith the mouth loosely closed, in one of the 1 ger compartments. One of the monkeys immediately . I’fuoached, cautiously opened the bag a little, peeped p’ tlnc^ instantly dashed away. Then I witnessed what jj1'1'111 has described, for monkey after monkey, with raised high and turned on one side, could not at hddng momentary peeps into the upright bag, \v ^r°a ‘ Memoire sur les Microcepliales,' 1S67, p. 168. 1 he A ariation of Animals and Plants under Domestication,’ vol- l. p. 2o MENTAL POWERS. 45 Cu. «\ II. ' Particular monkey would turn out a good actor, lie i- s"eiecl that it all depended on their power of atten- cn- If when he was talking and explaining anything- a ni°nkey, its attention was easily distracted, as by to In ' i°n or other trifling object, the case was peless. If ]ie tried by punishment to make an in- ] ontive monkey act, it turned sulky. On the other ' lir> a monkey which carefully attended to him could be trained. 18 almost superfluous to state that animals have at ti en^ Memories for persons and places. A baboon g. . e Cape of Good Hope, as I have been informed by ^^rew Smith, recognised him with joy after an aLd tlCe "*uo montbs. I had a dog who was savage men aVeiSC t0 !|P strangers, and I purposely tried his Went°1^ a^ei an absence of five years and two days. I him Ueur stable where he lived, and shouted to b followed me out walking and obeyed me, stantl'1 monnor > bo showed no joy, but in- hefcn 'V aS ^ ^ bac^ parted with him only lmlf-an-hour year.^'i ^ train of old associations, dormant during five mf i ’ 1 , ^bus been instantaneously awakened in his I'ccoV . bbren ants, as 1’. Huber la has clearly shewn, m, °niSed their fellow-ants belonging to the same eom- Can 1 y after a separation of four months. Animals tir ?rtainly by some means judge of the intervals of of rpi 1UL4U1 tJJ-I li tJVtJLLlto. 10 Imagination is one of the highest prerogatives- tlie^m' tly this faculty he unites, independently of bant' 1 ' |'Jliner images and ideas, and thus creates bril- ai lvs,' ■ « who must reflect whether he shall make a novel results. A poet, as Jean Paul Hick ter 13 (ktr™ des F°unnis,’ 1610, p. 150. i pp pg 22^r' Maudsley’s ‘ Physiology and Pathology of Mil 18G8, 46 THE DESCENT OF MAN. Part I- character say yes or no — to the devil with him ; he is “ onhr a stupid corpse.” Dreaming gives ns the best notion of this power; as Jean Paul again says, “The “ dream is an involuntary art of poetry.” The value of the products of our imagination depends of course o» the number, accuracy, and clearness of our impressions ; on our judgment and taste in selecting or rejecting the involuntary combinations, and to a certain extent o» our power of voluntarily combining them. As dogs, cats, horses, and probably all the higher animals, even birds, as is stated on good authority,14 have vivid dreams, and this is shewn by their movements and voice, we must admit that they possess some power of imagination. Of all the faculties of the human mind, it will, 1 presume, be admitted that Reason stands at the summit* Few persons any longer dispute that animals possess some power of reasoning. Animals may constantly be seen to pause, deliberate, and resolve. It is a significant fact, that the more the habits of any particular animal are studied by a naturalist, the more he attributes to reason and the less to unlearnt instincts.13 In future chapters we shall see that some animals extremely low in the scale apparently display a certain amount of reason- iSo doubt it is often difficult to distinguish between the power of reason and that of instinct. Thus Dr. Haves, in his work on ‘The Open Polar Sea,’ repeatedly "re- marks that his dogs, instead of continuing to draw the sledges in a compact body, diverged and separated when they came to thin ice, so that their weight might be more evenly distributed. This was often the first’ warn- 14 ®r- Jordon, ‘ Birds of India,’ vol. i. 1S02, p. xxi. H. Morgan’s work on ‘ The American Beaver,’ 18GS offers a good illustration of this remark. I cannot, however, avoid thinking that he goes too far in underrating tho power of Instinct. MENTAL POWERS. 47 ■Cji. AP. II. "S and notice which the travellers received that the ice "as ^econiing thin and dangerous. Now, did the dogs ?.( * ^llls from the experience of each individual, or from the example of the older and wiser dogs, or from an ^ i'-rited habit, that is from an instinct? This instinct 'ght possibly have arisen since the time, long ago, . °n dogs were first employed by the natives in draw- oi^ ^1G'r sk‘dges ; or the Arctic wolves, the parent-stock ■ ^le Esquimaux dog, may have acquired this instinct, ^Tolling them not to attack their prey in a close pack qen on thin ice. Questions of this kind are most *®cufr to answer. si, many facts have been recorded in various works ^owrng that animals possess some degree of reason, '■d I wip here give only two or three instances, authen- utcd Py iJengge^ and relating to American monkeys, j s ^ 1 ®tand low in their order. He states that when . . lsf gave eggs to his monkeys, they smashed them rr U lost much of their contents ; afterwards they q/v. p one end against some hard body, and picked ^ f ie bits of shell with their fingers. After cutting lire llSe ves °nfy once with any sharp tool, they would touch it again, or would handle it with the greatest Lumps of sugar were often given them wrapped llP in Paper; and Iiengger sometimes put a live wasp stu Pal>efr so that in hastily unfolding it they got lieh8 ’ after 1:11 is liale’ domesticates other animals, possesses property, or l3l°JTs language; that no other animal is self-con- Cl°Us’ c°mprehends itself, has the power of abstraction, of |)0SSesses general ideas ; that man alone has a sense bid eUUt“'’ *s liable to caprice, has the feeling of grati- mystery, &c. ; believes in God, or is endowed with Conscience. I will hazard a few remarks on the more ^Portant a and interesting of these points. ^ ebbishop Sumner formerly maintained18 that man lle ls capable of progressive improvement. With n. • pvv Vi Y U JUXjJiV/ » CpUJULUi »» A l/AA 11 ms, looking first to the individual, everv one who Uls had any experience in setting traps knows that -J VAAp WA iV'J VO JAA OV VAX VA X4X1V M U va»wv old aai,nals can be caught much more easily than iJy an ones ; and they can he much more easily approached enemy. Even with respect to old animals, it is ^possible to catch many in the same place and in the 0|""' kind of trap, or to destroy them by the same kind ■ i,01s°n j yet it is improbable that all should have j,. °f the poison, and impossible that all should I e ,een caught in the trap. They must learn caution Am^lng brethren caught or poisoned. In North UlCa> where the fur-hearing animals have long been Quoted by g;r (j. Lyell, • Antiquity of Mali,’ p. -107. ' I- E 50 THE DESCENT OE MAN. Pakt I- pursued, they exhibit, according to the unanimous tes- timony of all observers, an almost incredible amount of sagacity, caution, and cunning ; hut trapping has been there so long carried on that inheritance may have come into play. If we look to successive generations, or to the race, there is no doubt that birds and other animals gradually both acquire and lose caution in relation to man or other enemies ; 19 and this caution is certainly in chief part an inherited habit or instinct, but in part the result of individual experience. A good observer, Leroy,20' states that in districts where foxes are much hunted, the young when they first leave their burrows are in- contestably much more wary than the old ones in dis- tricts where they are not much disturbed. Our domestic dogs are descended from wolves and jackals,21 and though they may not have gained in cunning, and may have lost in waryness and suspicion, yet they have progressed in certain moral qualities, such as in affection, trust-worthiness, temper, and pro- bably in general intelligence. The common rat has conquered and beaten several other species through- out Europe, in parts of North America, New Zealand, and recently in Formosa, as well as on the mainland of China. Mr. Swinhoe,22 who describes these latter cases, attributes the victory of the common rat over the large Jlks coninga to its superior cunning; and this latter quality may be attributed to the habitual exercise of all its faculties in avoiding extirpation by man, as well 10 1 .Journal of Researches daring the Voyage of the “ Beagle,” ’ 18-15, p. 398. ‘ Origin of Species,’ 5th edit. p. 200. 20 ‘Lcttres Phil, sur l’lntelligenee des Aninmux,’ nouvello edit- 1802, p. 86. 21 See the evidence on this head in chap. i. vol. i. ‘ On the Variation of Animals and Plants under Domestication,’ 22 ‘ Proc. Zoolog. Soc.’ 1801, p. ISO. MENTAL POWERS. 51 j.8 dearly all the less cunning or weak-minded rats ^6en successiTely destroyed by him. To main- a . ’ 111 dependent! v of any direct evidence, that no infill sIiP his hand to the other end, and use it in tionPi°Per rnanner as a h;ver. In the cases just men- hut tl Stones and sticks were employed as implements ; °Q tl 1Gp aro likewise used as weapons. Erehm 25 states, that ^ a,dhority of the well-known traveller Schimper, specii>n ^yssinia when the baboons belonging to one fain.1' 8 ^a^a) descend in troops from the moun- ts 0 Plunder the fields, they sometimes encounter fjrr] hS °f another species (C. hamadryas), and then a the tt1181168- phe Geladas roll down great stones, which amadryas try to avoid, and then both species, 1 813.44^° Wyman in ‘Boston Journal of Nat. Hist.’ vol. iv. a i g.’. p' ' “?■ 2s irn.nSetliiere yon Pamo-„o„ > iaon = 51-56. i83°’ s- uebcn, B. i. s> 79 j g2- E 2 52 TliE DESCENT OP MAN. Taut I. making a great uproar, rush furiously against each other. Brehm, when accompanying the Duke of Cohura- Gotha, aided in an attack with fire-arms on a troop of baboons in the pass of Mensa iu Abyssinia. The baboons in return rolled so many stones down the mountain, some as large as a man’s head, that the attackers had to beat a hasty retreat ; and the pass was actually for a time closed against the caravan. It deserves notice that these baboons thus acted in concert. Mr. Wal- lace25 on three occasions saw female orangs, accom- panied 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.” In the Zoological Gardens a monkey which had weak teeth used to break open nuts with a stone ; and I was assured by the keepers that this animal, after using the stone, 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 21 remarks, that the fashioning of an implement tor a special purpose is absolutely peculiar to man ; and ho considers that this forms an immeasur- able gulf between him and the brutes. It is no doubt a very important distinction, but there appears to me much truth in Sir J. Lubbock’s suggestion,28 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 intentionally break the :s ‘ The Malay Archipelago,’ vol. i. 1S69, p. 87. 27 1 Primeval Man,’ 1869, pp. 14a, 147. 26 • Prehistoric Times,’ 1865, p. 473, flic. Chap. II. MENTAL POWERS. Oi> flints, and not a very wide step to rudely fashion them, flflis latter advance, however, may have taken long ages, if we may judge by tire immense interval of time which elapsed before the men of the neolithic period took to grinding and polishing their stone tools. In breaking the Hints, as Sir J. Lubbock likewise remarks, sparks would have been emitted, and in grinding them beat would have been evolved: “thus the two usual “ Methods of obtaining fire may have originated.” The Mature of fire would have been known in the many Volcanic regions where lava occasionally flows through Crests. The anthropomorphous apes, guided probably by instinct, build for themselves temporary platforms ; but as many instincts are largely controlled by reason, *be simpler ones, such as this of building a platform, rnjght readily pass into a voluntary and conscious act. bbe orang is known to cover itself at night with the foaves of the Pandanus ; and Brehm states that one of bis baboons used to protect itself from the heat of the sun by throwing a straw-mat over its head. In these iatter habits, we probably see the first steps towards s°nre of the simpler arts ; namely rude architecture aud dress, as they arose amongst the early progenitors °f man. Language. — -This faculty has justly been considered as °ne of the chief distinctions between man and the lower animals. But man, as a highly competent judge, Arch- bishop Whately remarks, “ is not the only animal that ' can make use of language to express what is passing in ‘ bis mind, and can understand, more or less, what is so “ expressed by another.” -9 In Paraguay the Cebus azaree when excited utters at least six distinct sounds, which Quoted in ‘Anthropological Review,’ 1804, p. 158. 54 THE DESCENT OP 1WAN, Part I. excite in other monkeys similar emotions.30 The move- ments of the features and gestures of monkeys are un- derstood by us, and they partly understand ours, as Rengger and others declare. It is a more remark- able fact that the dog, since being domesticated, has learnt to bark31 in at least four or five distinct tones. Although barking is a new art, no doubt the wild spe- cies, the parents 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 ; the yelping or howling bark of despair, as when shut up ; that of joy, as when starting on a walk with his master; and the very distinct one of demand or supplication, as when wishing for a door or window to be opened. Articulate language is, however, peculiar 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.33 This especially holds good with the more simple and vivid feelings, which are but little connected with our higher intelligence. Our cries of paiu, fear, surprise, anger, to- gether with their appropriate actions, and the murmur of a mother to her beloved child, are more expressive than any words. It is not the mere power of articula- tion that distinguishes man from other animals, for as every one knows, parrots can talk; but it is his large power of connecting definite sounds with definite ideas ; and this obviously depends on the development of the mental faculties. 30 Kenggor, ibid. g. 43. 31 Sec my ‘ Variation of Animals and Plants under Domestication ’ vol. i. p. 27. 32 See a discussion on this subject in Mr. E. B. Tylor’s veiy interest- ing work, ‘Researches into the Early History of Mankind,’ IStio, chaps, ii. to iv. ■ClUp. II. MENTAL POWERS. 55 As Horne Tooke, 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 winch, more appropriate simile. It certainly is not a h'Ue instinct, as every language has to be "learnt. It differs, however, widely from, all ordinary arts, for man *las an instinctive tendency to speak, as we see in the babble of our young children ; whilst no child has an lustinctivc tendency to brew, bake, or write. Moreover, j10 philologist now supposes that any language has 1;,een deliberately invented ; each has been slowly and ^consciously 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 that have the power °f singing exert this power instinctively ; but the actual Song> and even the call-notes, are learnt from their Parents or foster-parents. These sounds, as Dailies Barrington 33 has proved, “ are no more innate than language is in man.” The first attempts to sing lu;iy be compared to the imperfect endeavour in a “.child to babble.” The young males continue prac- tising, or, as the bird-catchers say, recording, for ten r other object to the early progenitors or founders of a tribe, aro sup- posed after a long interval to represent the real progenitor of the tribe ; and such animat or object is then naturally believed still to exist a spirit, is held eacred, and worshipped as a god. Nevertheless I cannot but suspect that there is a still earlier and ruder stage, when anything which manifests power or movement is thought to bo endowed with some form of life, and with mental faculties analogous to our own. CiUr. II. MENTAL POWERS. 67 ilie tendency in savages to imagine that natural objects and agencies are animated by spiritual or living essences, is perhaps illustrated by a little fact which 1 °uce noticed : my dog, a full-grown and very sensible mnmal, was lying on the lawn during a hot and still Uay ; but at a little distance a slight breeze occasionally moved an open parasol, which would have been wholly disregarded by the dog, had any one stood near it. As "'as, every time that the parasol slightly moved, the growled fiercely and barked. He must, I think, have reasoned to himself in a rapid and unconscious fanner, that movement without any apparent cause “‘bicated the presence of some strange living agent, and 110 stranger had a right to be on his territory. bhe belief in spiritual agencies would easily pass into le belief in the existence of one or more gods. For Sa,Vages would naturally attribute to spirits the same passions, the same love of vengeance or simplest form justice, and the same affections which they themselves experienced. The Fuegians appear to be in this respect jn au intermediate condition, for when the surgeon on °ard the “ Beagle ” shot some young ducklings as sPeciniens, York Minster declared in the most solemn manner, “ Oh ! Mr. Bynoe, much rain, much snow, blow' much and this wras evidently a retributive punish- ment for wasting human food. So again lie related l0w> when liis brother killed a “ wild man,” storms long ]'aged, much rain and snow' fell. Yet we eoidd never c iscover that the Fuegians believed in w'hat we should a God, or practised any religious rites ; and Jemmy utton, with justifiable pride, stoutly maintained that mre was no devil in his land. This latter assertion is 10 more remarkable, as with savages the belief in . spirits is far more common than the belief in good spirits. 68 THE DESCENT OE MAN. Part 1. The feeling of religious devotion is a highly com- plex one, consisting of love, complete submission to an exalted and mysterious superior, a strong sense of dependence, 54 fear, reverence, gratitude, hope for the future, and perhaps other elements. No being could experience so complex au emotion until advanced in his intellectual and moral faculties to at least a mode- rately 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 ab- sence, and, as I may add, ot a monkey to his beloved keeper, is widely different 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 Braubach55 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 unseen spiritual agencies, then in fetish- ism, polytheism, and ultimately in monotheism, would infallibly lead him, as long as his reasoning pow'ers remained poorly developed, to various strange super- stitions 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 our 54 See an able article on the rKj'ekioal Elements of Religion, by Mr. L. Owen Pike, in • Anthropolog. Review,’ April, 1870, p. Ixiii. 55 1 Religion, Moral, &e., der Daiwin’schcn Art-T.ehre,’ 1869, s. 53. ClIAP. IIg MENTAL POWERS. 69 Uf-cumulatccl knowledge.56 As Sir J. Lubbock lias well observed, “ it is not too muck 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 Acuities may be compared with the incidental and occasional mistakes of the instincts of the lower animals. 50 ‘Prehistoric Times,’ 2 ad edit. p. 571. In this work (at p. 553) oiere will bo found an excellent account of the many strange and capricious customs of savages. 70 THE DESCENT OF MAN. Part L CHAPTER III. Comparison of tiie Mental Powers of Man and the Lower Animals — continued. The moral sense — Fundamental proposition — The qualities of social animals Origin of sociability — Struggle between opposed in- stincts Man a social animal — The more enduring social instincts conquer other less persistent instincts — The social virtues alone regarded by savages — - T he self-regarding virtues acquired at a later stage of development — The importance of the judgment of the members of the same community on conduct Trans- mission 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 Mack- intoshJ remarks, “has a rightful supremacy over every other principle ot human action; ’ it is summed up in that short but imperious word ought, so full of high significance. It is the most noble of all the attributes of man, leading him without a moment’s hesitation 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. Immanuel Kant exclaims, “ Duty ! Wondrous thought, “ that workest neither by fond insinuation, flattery, nor “ bY any threat, but merely by holding up thy naked “ blw in the soul, and so extorting for thyself always 1 See, for instance, on this subject, Quatrefages, ‘ Unite' de l’Espece Humaine,’ 1S(J1, p. 21, &c. 2 ‘ Dissertation on Ethical Philosophy,’ 1837, p. 231, Ac. 'Chap. ni. MO UAL SENSE. 71 “ reverence, if not always obedience ; before whom all “ appetites are dumb, however secretly they rebel ; ‘ whence thy original ?”3 This great question has been discussed by many Writers4 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 ap- proached it exclusively from the side of natural history. The investigation possesses, also, some independent in- terest, as an attempt to see how far the study of the lower animals can throw light on one ol the highest Psychical faculties of man. The following proposition seems to me in a high degree probable— namely, that any animal whatever, endowed with well-marked social instincts,5 * * * * * 11 would inevi- tably acquire a moral sense or conscience, as soon as 3 1 Metaphysics of Ethics,* translated by J. \V. Semple. Edinburgh, l836, p. 136. _ 4 Mr. Bain gives a list (‘Mental and Moral Science,’ 18G8, p. o43- ' -“•!) of twenty-six British authors who have written on this subject, and whoso names arc familiar to every reader ; to these, Mr. Bain’s own llame, and those of Mr. Becky, Mr. Sbadworth Hodgson, and Sir J. Lubbock, as well as of others, may be added. t * Sir B. Brodie, after observing that man is a social animal (‘ x’sy- ehological Enquiries,’ 1854, p. 102), asks tiro pregnant question, ‘‘ ought not this to settle the disputed question as to the existence ot a 11 moral sense ?” Similar ideas have probably occurred to many persons, as they did long ago to Marcus Aurelius. Mr. J. 8. Mill speaks, in Lis celebrated work, ‘ Utilitarianism,’ (1864, p. 40), of the social feelings a “powerful natural sentiment,’’ and as tho natural basis of “sentiment for utilitarian morality;” but on the previous page he says, “if, as is my own belief, the moral -feelings are not innate, but . acquired, they are not for that reason less natural. It is w ith hesita- tion that I venture to differ from so pro! mold a thinker, hut it can hardly ho disputed that the social feelings are instinctive or innate in the lower animals ; and why should they not bo so ill man ? Mr. Bain (see, for instance, * The Emotions and the Will,’ 18G5, p. 481) and others believe that the moral sense is acquired by each individual during his lifetime. On the general theory of evolution .this is at least extremely improbable. 72 THE DESCENT OF MAN. J’aet I- its intellectual powers Lad become as well developed, 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 evi- dently 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 he incessantly passing- through the brain of each individual ; and that feeling of dissatisfaction 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 behind it a very vivid impres- sion. It is clear that many instinctive desires, such as that of hunger, are in their nature of short duration r and after being satisfied are not readily or vividly re- called. Thirdly, after the power of language had been acquired aud the wishes of the members of the same community could be distinctly expressed, the common opinion how each member ought to act for the public good, would naturally become to a large extent the guide to action. But the social instincts would still give the impulse to act for the good of the community, this im- pulse being strengthened, directed, and sometimes even deflected by public opinion, the power of which rests, as we shall presently see, on instinctive sympathy. Lastly,. habit in the individual would ultimately play a very Chap, m. MORAL SENSE. 78'. important part in guiding tlie conduct of each member ; the social instincts and impulses, like all other in- stincts, would be greatly strengthened by habit, as " Quid obedience to the wishes and judgment of the com- munity. These several subordinate propositions must n°w 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 intellec- tual faculties were to become as active and as highly 'leveloped as in man, would acquire exactly the same moral sense as ours. In the same manner as various uuirnals have some sense of beauty, though they admire "idely different objects, so they might have a sense of llght and wrong, though led by it to follow widely dif- ferent lines of conduct. If, for instance, to take an ex- ti'erne 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- Jee‘S, 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 other social animal, would in our sup- pled case gain, as it appears to me, some feeling of 1]ght and wrong, or a conscience. For each individual A' °Uld 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 which impulse should be followed; and satis- taction or dissatisfaction would be fedt, as past impres- S1°ns were compared during their incessant passage through the mind. In this case an inward monitor 'v°uld tell the animal that it would have been better to have followed the one impulse rather than the other. ^ he one course ought to have been followed : the one 74 TIIE DESCENT OP HAN. Part I. "would have been right and the other wrong; but to these terms I shall have to recur. Sociability. Animals of many kinds are social ; we fiud even distinct species living together, as with some American monkeys, and with the united flocks of rooks, jackdaws, and starlings. Man show's the same feeling in his strong love for the dog, which the dog returns v'ith interest. Every one must have noticed how mise- rable horses, dogs, sheep, &c. are when separated from their companions ; and what affection at least the tvvo foi mer kinds show on their reunion. Xt is curious to speculate on the feelings of a dog, who will rest peace- fully 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 dis- mally. We will confine our attention to the higher social animals, excluding insects, although these aid each other in many important ways. The most common sen ice which the higher animals perform for each other, is the warning each other of danger by means of the united senses ol all. Every sportsman knows, as Dr. Jaeger remarks,6 how difficult it is to approach animals m a herd or troop. Wild horses and cattle do not, I believe, make any danger-signal ; but the attitude of any one w'ho first discovers an enemy, warns the others. Rabbits stamp loudly on the ground with their hind-feet as a signal : sheep and chamois do the same, but with their fore-feet, uttering likewise a whistle. Many birds and some mammals post sentinels, which in the case of seals are said7 generally to be the females. The leader of a troop of monkeys acts as the sentinel, and utters •cries expressive both of danger and of safety.8 Social 6 ‘Die Darwiu’sohe Tlieorie,’ s. 101. Mr. It. Brown in ‘Proc. Zoolog. Soc.’ 18G8 p 409 ’ Brehm, ‘Thierleben,’ B. i. 1804, s. 52, 79. ‘ For tlic case of the ^up. hi. MORAL SENSE. 75 •animals perform many little services for each other: horses nibble, and cows lick each other, on any spot "hicli itches : monkeys search for each other s external Parasites ; and Brehm states that after a troop of the ^ercopithecus griseo-viridis has rushed through a thorny brake, each monkey stretches itself on a branch, and another monkey sitting by “conscientiously” examines its fur and extracts every thorn or burr. Animals also render more important services to each other: thus wolves and some other beasts of prey hunt in packs, and aid each other in attacking their victims. ■Pelicans iish in concert. The Hamadryas baboons turn over stones to find insects, &c. ; and when they come to a large one, as many as can stand round, turn it over together and share the booty. Social animals mutually defend each other. The males of some ruminants come to the front when there is danger and defend the herd with their horns. I shall also in a future chapter give eases of two young wild bulls attacking an old one in eoncert, and of two stallions together trying to drive away a third stallion from a troop of mares. Brehm encountered in Abyssinia a great troop of baboons which were crossing a valley : some had already ascended the opposite mountain, and some were still in the valley : tlje latter were attacked by the dogs, but the old males immediately hurried down from the rocks, and witn mouths widely opened roared so fearfully, that the dogs Precipitately retreated. They were again encouraged to the attack ; but by this time all the baboons had le- nscended the heights, excepting a young one, about six •wonkeys extracting thorns from each other, see s. 54. \\ ith respect to the Hamadryas turning over stones, the fact is given (s. 76) on the evidence of Alvarez, whose observations Brehm thinks quite trust- worthy. 1’or the cases of the old male baboons attacking the dogs, see s- 79 ; and with respect to the eagle, s. 56. 70 THE DESCENT OF MAH. Part I. months old, who, loudly calling for aid, climbed on a block of rock and was surrounded. Now one of the largest males, a true hero, came down again from the mountain, slowly went to the young one, coaxed him, and triumphantly led him away — the dogs being too much astonished to make an attack. I cannot resist giving another scene which was witnessed by this same naturalist; an eagle seized a young Cercopithecus.. which, by clinging to a branch, was not at once carried off; it cried loudly for assistance, upon which the other members of the troop with much uproar rushed to the rescue, surrounded the eagle, and pulled out so many feathers, that he no longer thought of his prey, but only how to escape. This eagle, as Urchin remarks, assuredly would never again attack a monkey in a troop. It is certain that associated animals have a feeling of love for each other which is not felt by adult and non- social animals. How far in most cases thev actually sympathise with each other’s pains and pleasures is more doubtful, especially with respect to the latter. Mr. Buxton, however, who had excellent means of observation, states that his macaws, which lived free in Norfolk, took “an extravagant interest” in a pair with a nest, and whenever the female left it, she was surrounded by a troop “screaming horrible accla- “ mations in her honour.” It is often difficult to judge whether animals have any feeling for each other's sufferings. Who can say what cows feel, when they surround and stare intently on a dying or dead companion? That animals sometimes are far from feeling any sympathy is too certain ; for they will expel a wounded animal from the herd, or gore or worry it to death. This is almost the blackest tact in natural 9 ‘ Annals and Mag. of Nat. Hist.’ November, 1808, p. 382. ■Chap. III. MORAL SENSE. 77 history, unless indeed the explanation which has been suggested is true, that their instinct or reason leads them to expel an injured companion, lest beasts of prey, including man, should be tempted to follow the troop. In this ease their conduct is not much worse than that of the North American Indians who leave their feeble comrades to perish on the plains, or the Feegeans, who, when their parents get old or fall ill, bury them alive.10 Many animals, however, certainly sympathise with each other’s distress or danger. This is the case even with birds ; Capt. Stansburyu found on a salt lake in Utah an old and completely blind pelican, which was Wery fats and must have been long and well fed by his companions. Mr. Blyth, as he informs me, saw Indian crows feeding two or three of their companions which Were blind ; and I have heard of an analogous case with the domestic cock. We may, if we choose, call these actions instinctive ; hut such cases are much too rare for the development of any special instinct.12 I have myself seen a dog, who never passed a great triend of his, a cat which lay sick in a basket, with- out giving her a few licks with his tongue, the surest S]gn of kind feeling in a dog. It must be called sympathy that leads a courageous •log to fly at any one who strikes his master, as he certainly will. I saw a person pretending to beat a lady who had a very timid little dog on her lap, and the trial hail never before been made, the little crea- 10 Sir J. Lubbock, ‘ Prehistoric Times,’ 2nd edit. p. 4L0. " As quoted by Mr. L. H. Morgan, * The American Beaver,’ 18G8, 1». 272. Capt. Stanabury also gives an interesting account of the man- ncr in which a very yonng pelican, carried away by a strong stream, m as guided and encouraged in its attempts to reach the shore by half a dozen old birds. 12 As Mr. Bain states, “ effective aid to a sufferer springs from sym- pathy proper:” ‘ Mental and Moral Science,’ 1808, p. 245. 78 THE DESCENT OF MAN. Part I- ture instantly jumped away, but after the pretended beating was over, it was really pathetic to see how per- severingly he tried to lick bis mistress’s face and com- fort her. Brehm53 states that when a baboon in con- finement was pursued to be punished, the others tried to protect him. It must have been sympathy in the cases above given which led the baboons and Cercopi- theci to defend their young comrades from the dogs and the eagle. I will give only one other instance of sympathetic and heroic conduct in a little American monkey. Several years ago a keeper at the Zoological Gardens, showed me some deep and scarcely healed wounds on the nape of his neck, inflicted on him whilst kneeling on the floor by a fierce baboon. The little American monkey, who was a warm friend of this keeper, lived in the same large compartment, and was dreadfully afraid of the great baboon. Nevertheless, as soon as he saw his friend the keeper in peril, he rushed to the rescue, and by screams and bites so distracted the baboon that the man was able to escape, after running' great risk, as the surgeon who attended him thought, of his life. Besides love and sympathy, animals exhibit other qualities which in us would be called moral ; and I agree with Agassiz14 that dogs possess something very like a conscience. They certainly possess some power of sell- command, and this does not appear to be wholly the result of fear. As Braubach15 remarks, a dog will refrain from stealing food in the absence of his master. Dogs have long been accepted as the very type of fidelity and obedience. All animals living in a body which defend each other or attack their enemies 13 ‘ Thierleben,’ B. i. s. 85. 14 ‘ Do l’Espece et de la Class.’ 18G9, p. 97. 15 ‘Dor Darwin’selien Avt-Lchre,’ 1809, s. 51. Uhap. III. MORAL SENSE. 79 in concert, must be in some degree faithful to each other; and those that follow a leader must be in some degree obedient. When the baboons in Abys- sinia16 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; but as soon as they are sure that there is no danger, all show their joy by much clamour. With respect to the impulse which leads certain nnimals to associate together, and to aid each other 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 performing other instinctive notions ; or by the same sense of dissatisfaction, as in other cases of prevented instinctive actions. We 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 ilock of sheep, hut not in worrying them ; a young foxhound delights in hunting a fox, whilst some other kinds of dogs as I have witnessed, utterly disregard foxes. What a strong feeling of inward satisfaction must impel a bird, s° full of activity, to brood day after day over her eggs. -Migratory birds are miserable if prevented from migiat- ing, and perhaps they enjoy starting on their long flight. Some few instincts are determined solely by Painful feelings, as by fear, which leads to self-preser- vation, or is specially directed against ceitain enemies. -No one, I presume, can analyse the sensations of pleasure or pain. In many eases, however, it is pro- bable that instincts are persistently followed from the 16 Brelim, 1 Thierleben,’ B. i. s. 76. ■so THE DESCENT OF MAN. Part I. mere force of inheritance, without the stimulus of either pleasure or pain. A young pointer, when it first scents game, apparently cannot help pointing. A squirrel in a cage who pats 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 hy experiencing some pleasure or pain may be erro- neous. Although a habit may be blindly and implicitly followed, independently of any pleasure or pain felt at the moment, yet if it be forcibly and abruptly checked, vague sense of dissatisfaction is generally expe- rienced ; and this is especially true in regard to persons of feeble intellect. It has often been assumed that, animals were in the first place rendered social, and that they feel as a con- sequence uncomfortable when separated from each other, and comfortable whilst together; but it is a more pro- bable view that these sensations were first developed, in order that those animals which would profit bv living in society, should be induced to live together. In the same manner as the sense of hunger ami the pleasure of eating were, no doubt, first acquired in order to induce animals to eat. rJ he feeling of pleasure from society is probably an extension of the parental or filial affec- tions ; and this extension may be in chief part attributed to natural selection, but perhaps in part to mere habit. For with those 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 com- rades and lived solitary would perish in greater numbers. "With respect to the origin of the parental and filial affections, which apparently lie at the basis of the social affections, it is hopeless to speculate ; but we Ciur. in. MORAL SENSE. 81 1T‘av infer that they have been to a large extent gained through natural selection. So it has almost certainly been with the unusual and opposite feeling of hatred between the nearest relations, as with the worker-bees whick kill their brother-drones, and with the queen-bees 'vhich kill their daughter-queens ; the desire to destroy, histead of loving, their nearest relations having been here of service to the community. The all-important emotion of sympathy is distinct h'otn that of love. A mother may passionately love her sleeping and passive infant, but she can then hardly be said to feel sympathy for it. The love ol a man for his dog is distinct from sympathy, and so is that of a hog for his master. Adam Smith formerly argued, as has j\fr. Bain recently, that the basis of sympathy lies 111 our strong retentiveness of former states of pain or Pleasure. Hence, “ the sight of another person enduring hunger, cold, fatigue, revives in us some recollection °1 these states, which are painful even in idea. ’ We aro thus impelled to relieve the sufferings of another, order that our own painful feelings may bo at the sanae time relieved. In like manner we are led to Participate in tbe pleasures of others.17 But I cannot fee bow this view explains tbe tact that sympathy :'s excited in an immeasurably stronger degree by a beloved than by an indifferent person. Tlie mere , ' Sec ihe first and striking chapter in Adam Smiths ‘ i heory of moral Sentiments.’ Also Mr. Bain’s ‘Mental and Moral Science,’ p. 244, and 275-282. Mr. Rain states, that “sympathy is, ' ittdirectly, a source of pleasure to the sympathiser;” and he accounts (lor this through reciprocity. He remarks that “ tin; person benefited, (l or °thers in his stead, may make up, by sympathy and good offices returned, for all tin; sacrifice.” But if, as appears to be ttie ease, if nPatl‘y 18 ^rictly an instinct, its exercise would give direct pleasure, llle same manner as the exercise, as before remarked, of almost every otller instinct. V0L. I. G 82 THE DESCENT OP MAN. Paet I. sight of suffering, independently of love, would suffice to call up in us vivid recollections and associations. Sympathy may at first have originated in the manner above suggested; but it seems now to have become an instinct, which is especially directed towards be- loved objects, in the same manner as fear with ani- mals is especially directed against certain enemies. As sympathy is thus directed, the mutual love of the members of the same community will extend its limits. No doubt a tiger or lion feels sympathy for the suffer- ings of its own young, but not for any other animal. With strictly social animals the feeling will be more or less extended to all the associated members, as wo know to be the case. With mankind selfishness, expe- rience, and imitation probably add, as Mr. Bain has shewn, 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 there can he no doubt that the feeling of sympathy is much strengthened by habit. In however complex a manner this feeling may have originated, as it is ono of high importance to all those animals which aid and defend each other, it will have been increased, through natural selection; for those communities, which included the greatest number of the most sympathetic members, would flourish best and rear the greatest number of offspring. In many cases it is impossible to decide whether certain social instincts have been acquired through natural selection, or are the indirect result of other instincts and faculties, such as sympathy, reason, expe- rience, 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 'Wap. III. MORAL SENSE. 83 tile indirect result of any otlier faculty ; it must there- fore have been directly acquired. On the other lianc , tile habit followed by the males of some social animals, of defending the community and of attacking their demies or their prey in concert, may perhaps have originated from mutual sympathy ; but courage, and in most cases strength, must have been previously Acquired, probably through natural selection. Of the various instincts and habits, some are muc stronger than others, that is, some either give more Pleasure in their performance and more distress m their Prevention than others ; or, which is probably quite as Important, they are more persistently followed throng 1 inheritance without exciting any special feeling of plea- sure or pain. We are ourselves conscious that some habits are much more difficult to cure or change than °thers. Hence a struggle may often be observed in animals between different instincts, or between an instinct and some habitual disposition ; as when a dog bushes after a hare, is rebuked, pauses, hesitates, pursues again or returns ashamed to his master ; or as between ihe love of a female dog for ber young puppies and for her master, for slie may be seen to slink away to them, as if half ashamed of not accompanying her master. But the most curious instance known to me of one instinct conquering another, is the migratory instinct conquering the maternal instinct. The former is won- derfully strong; a confined bird will at tlie proper season beat her breast against the wires of her cage, until if is hare and bloody. It causes young salmon to leap ()ut of the freshwater, where they could still continue to tive, 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- 84 THE DESCENT OF MAN. Part 1- preservatiou. Nevertheless the migratory instinct is so powerful that late in the autumn swallows and house- martins frequently desert their tender young, leaving them to perish miserably in their nests.18 We can perceive that an instinctive impulse, if it be in any way more beneficial to a species than some other or opposed 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 well 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 para- mount force. Man a social animal. — Most persons 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 confinement is one of the severest punishments which can be inflicted. Some authors sup- pose that man primevallv 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 are always, as far as I can discover, friendly with other families inhabiting the same district. Such families occasionally meet in council, and they unite tliiw fact, the Kcv. J '■ Jouyus states (sea his edition of 1 Whiter Nat. Hist, of Selbome,’ 1853, p. 204) was first recorded Ly the illus- trious Jenner, in 1 Phil. Transact.’ 1824, and has since been confirmed by several observers, especially by Mr. Blackball. This latter careful' observer examined, late in the autumn, during two years, thirty-six nests; he found that twelve contained young dead birds, five contained eggs ou the point of being hatched, and three eggs not nearly hatched- Many birds not yet old enough for a prolonged flight are likewise deserted and leit behind. See Blackwall, ‘ Kesearches in Zoology,' 1834, pp. 108, 118. For some additional evidence, ulthou have been producing corresponding modifications, " "hick, hy continued transmission and accumulation, hav'e become in us certain faculties of moral intuition — “ cei'fain emotions responding to right and wrong con- duct, which have no apparent basis in the individual experiences of utility. There is not the least inhe- rent improbability, as it seems to me, in virtuous ten- dencies being more or less strongly inherited ; for, not to mention the various dispositions and habits trans- mitted by many of our domestic animals, I have heard of 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 so rare a crime in the wealthy classes, we can hardly account by accidental coincidence for the tendency occurring in two or throe members of the same family. If bad tendencies are transmitted, it is probable that good ones are likewise transmitted. Ex- cepting through the principle of the transmission of moral tendencies, we cannot understand the differences believed to exist in this respect between the various races ot mankind. We have, however, as yet, hardly sufficient evidence on this head. Even the partial transmission of virtuous tendencies would be an immense assistance to the primary impulse derived directly from the social instincts, and indirectly from the approbation of our fellow-men. Admitting for the 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 organisation through habit, instruction, and example, continued during several generations in the same family, and in a quite subor- dinate degree, or not at all, by the individuals jvos- Chap. III. MORAL SENSE. 103 sessing 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, super- stitions, and tastes, such as the horror of a Hindoo tor unclean food, ought on the same principle to be trans- mitted. Although this in itself is perhaps not less pro- bable than that animals should acquire inherited tastes for certain kinds of food or fear of certain foes, I have not met with any evidence in support ot the trans- mission of superstitious customs or senseless habits. Finally, the social instincts which no doubt were acquired by man, as by the lower animals, for the goo of the community, will from the first have given to him some wish to aid his fellows, and some feeling ot sym- pathy. Such impulses will have served him at a very early period as a rude rule of right and wrong. Hut as man gradually advanced in intellectual power and was enabled to trace the more remote consequences ot ins actions; as he acquired sufficient knowledge to reject baneful customs and superstitions; as he regarded more and more not only the welfare but the happi- ness of his fellow-men ; as from habit, following on beneficial experience, instruction, and example, bis sympathies became more tender and " ic e y c 1 use , so as to extend to the men of all races, to the im- becile, the maimed, and other useless members ot society, and finally to the lower animals,— so would the standard of his morality rise higher and higher. An 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 37 A -writer in the ■ North British Review ’ (July, 1869, p. 531), well capable of forming a sound judgment, expresses himself strongly to ns 104 THE DESCENT OP MAN. Part I. 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 Ins lower, though at the moment, stronger impulses or desires. This, as Mr. Gal ton 36 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, analogous to that felt from other un- satisfied instincts, called in this case conscience ; for we cannot prevent past images and impressions continually passing through our minds, and these in their weakened state we compare with the ever-present social instincts, or with habits gained in early youth and strengthened during our whole lives, perhaps inherited, so that they are at last rendered almost as strong as instincts. 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 two last Chapters.— There 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 lorm an artful plan to plunder a garden— though lie could use stones for fighting or for breaking open nuts, effect Mr. Lecky (‘Hist, of Morals,’ vol. i extent to coincide ■ p. 143) seems to a certain Ire l)* lf A bi™4 011 Hereditary Genius,’ 1S69, p. 349. remarks on f A^yh ( Primeval Man,’ 1SS9, p. 188) has some good remarks on the contest in man’s nature between right and wrong The Chap. III. SUMMARY, 105 yet that the thought of fashioning a stone into a tool was quite beyond his scope. Still less, as he would admit, could he follow out a train ol metaphysical reasoning, or solve a mathematical problem, or reflect on God, ot 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 perceptions and simpler ■wants, the notion of expressing definite ideas by definite sounds had never crossed their minds. They might insist that they "'ere ready to aid their fellow-apes of the same troop in naany ways, to risk their lives for them, and to take charge of their orphans ; but they would be forced to acknowledge that disinterested love for all living crea- tures, the most noble attribute of man, was quite be- yond their comprehension. Nevertheless the difference in mind between man and the higher animals, great as it is, is certainly 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, mason, &c., of which man boasts, may bo found in an incipient, or even sometimes in a well-developed con- ation, in the lower animals. They are also capable of some inherited improvement, as we see in the domestic (l°g compared with the wolf or jackal. If it be main- fnined that certain powers, such as self-consciousness, "bs tract ion, &c., are peculiar to man, it may well be that these are the incidental results of other highly- ndvanced intellectual faculties; and these again are mainly the result of the continued use of a highly developed language. At what age does the new-born mfant possess the power of abstraction, or become self- 106 THE DESCENT OF MAN. Part I. conscious and reflect on its own existence ? We cannot answer ; nor can we answer in regard to the ascending organic scale. The half-art and half-instinct of lan- guage still bears the stamp of its gradual evolution. The ennobling belief in God is not universal with man ; and the belief in active spiritual agencies naturally fol- lows from his other mental powers. The moral sense perhaps affords the best and highest, distinction between man and the lower animals ; but I need not say any- thing on this head, as I have so lately endeavoured to shew that the social instincts, — the prime principle of man’s moral constitution 39 — 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. In a future 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 this at least is possible ought not to be denied, when we daily see their development in every infant; and when we may trace a perfect grada- tion from the mind of an utter idiot, lower than that of the lowest animal, to the mind of a New ton. " ‘ Tlie Thoughts of Marcus Aurelius,' &c., p. 139. C»A.P. IV. MANNER OP DEVELOPMENT. 107 CHAPTER IV. 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 ol life Effects of the increased use and disuse of parts— Arrested development — Re- version — Correlated variation — Rate of increase Checks to increase — Natural selection — Man the most dominant animal in the world — Importance ol his corporeal structure I he 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. We have seen in the first chapter that the homological structure of man, his embryological development and the rudiments which he still retains, all declare in the plainest manner that he is descended from some lower form. The possession of exalted mental powers is no insuperable objection to this conclusion. In order that an ape-like creature should have been transformed into ^an, it is necessary that this early form, as well as 111 any successive links, should all have varied in mind aud body. It is impossible to obtain direct evidence on this head ; but if it can be shewn that man now varies -that his variations are induced by the same general °hUses, and obey the same general laws, as in the case °f the lower animals — there can be little doubt that the preceding intermediate links varied in a like banner. The variations at each successive stage of descent must, also, have been in some manner accumu- lated and fixed. 108 THE DESCENT OP MAN. Part I. The facts and conclusions to be given in this chapter relate almost exclusively to the probable means by which the transformation of man has been effected, as far as his bodily structure is concerned. The fol- lowing chapter will be devoted to the development of his intellectual and moral faculties. But the present discussion likewise bears on the origin of the different races or species of mankind, whichever term may he preferred. It is manifest that man is now subject to much variability. 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.1 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.2 An emi- nent 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 1 ‘ Investigations in Military and Anthropolog. Statistics of American Soldiers,’ by B. A. Gould, 1869, p. 256. 2 With respect to the “ Cranial forms of the American aborigines, see Dr. Ail, ken Meigs in ‘ Pxoc. Aead. Nat. Sei.’ Philadelphia, Map 1866. On the Australians, see Huxley, in Lyell’s ‘ Antiquity of M»n> 1863, p. 87. On the Sandwich islanders, Prof. J. Wyman, ‘ Observa- tions on Crania,’ Boston, 1S08, p. 18. Chap. IV. MANNER OF DEVELOPMENT. 109 from 12,000 corpses how often each course prevails.3 The muscles are eminently variable : thus those of the foot were found by Prof. Turner4 not to be strictly alike in any two out of fifty bodies; and in some the deviations were considerable. Prof. Turner adds that the power of performing the appropriate movements must have been modified in accordance with the several deviations. Mr. J. Wood has recorded 5 the occurrence °f 295 muscular variations in thirty-six subjects, and in another set of the same number no less than 558 varia- tions, reckoning both sides of the body as one. In the last set, not one body out ol the thirty-six was found 11 totally wanting in departures from the standard de- “ seriptions of tire muscular system given in anatomical “ text-books.” A single body presented the extraordi- nary number of twenty-five distinct abnormalities. The sanre muscle sometimes varies in many ways : thus Trof. Macalister describes 0 no less than twenty distinct variations in the pedmaris accessorius. The famous old anatomist, Wolff,7 insists that the internal viscera are more variable than the external parts: Nulla particula cst quee non aliter et aliter in dliis se habeat hominibus. He has even written a treatise °n the choice of typical examples of the viscera for ^presentation. A discussion on the beau-ideal ot tlie liver, lungs, kidneys, &c., as of the human face divine, s°unds strange in our ears. The variability or diversity of the mental faculties *n men of the same race, not to mention the greater ‘ Anatomy of the Arteries,’ by B. Quain. 4 ‘ Transact. Royal Soc.’ Edinburgh, vol. xxiv. p. 175, 189. * 1 Proc. Royal Soc.’ 18G7, p. 51-1 ; also 1868, p. 483, 524. There is a Previous paper, 1866, p. 229. b ‘ Rroc. R. Irish Academy,’ vol. x. 1868, p. 141. 7 ‘Act. Acad.,’ St. Petersburg, 1778, part ii. p. 217. 110 THE DESCENT OF MAN. Part I. differences between tlie men of distinct races, is so notorious that not a word need here be said. So it is with the lower animals, as has been illustrated by a few examples in the last chapter. 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 under confinement in Africa had its own peculiar disposition and temper : he mentions 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 remark- able for intelligence. Rengger, also, insists on the di- versity 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.6 * 8 I have elsewhere 9 so fully discussed the subject of Inheritance that I need here add hardly anything. A greater number of 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 6 Brehm, 1 Thierleben,’ B. i. s. 58, 87. Kengger, ‘ Saugethiere von Paraguay,’ s. 57. u ' Variation of Animals and Plants under Domestication,’ vol. n* chap. xii. Chap. iv. MANNEB OF DEVELOPMENT. Ill How know through the admirable labours of Mr. G-alton 10 that genius, which implies a wonderfully complex com- bination of high faculties, tends to be inherited ; and, on the other hand, it is too certain that insanity and deteriorated mental powers likewise run in the same families. With respect to the causes of variability we are in ail cases very ignorant ; but we can see that in man as in the lower animals, they stand in some relation with the conditions to which each species has been exposed during several generations. Domesticated animals vary more than those in a state of nature ; aud this is appa- rently due to the diversified and changing nature of their conditions. The different races of man resemble in this respect 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 °f diversified conditions in the more civilised nations, the members of which belong to different grades of rank mid follow different occupations, presenting a greater range of character than the members of barbarous nations. But the uniformity of savages has often been exaggerated, and in some cases can hardly be said to exist.11 It is nevertheless an error to speak of man, even if we look only to the conditions to which he has been subjected, as “ far more domesticated ” u than 10 ‘Hereditary Genius : an Inquiry into its Laws and Consequences,’ 1869. 11 Mr. Bates remarks (• The Naturalist on the Amazons,’ 1863, vol. ii. J>- 159), with respect to the Indians of the same S. American tribe, jno two of them were at all similar in the shape of the head; one ( man had an oval visage with fine features, and another was quite ( Mongolian in breadth and prominence of cheek, spread of nostrils, aib(l obliquity of eyes.” 12 Blumenbach, 1 Treatises on Anthropolog.’ Eng. translate 1865, P- 205. 112 THE DESCENT OP MAN. Part l any other animal. Some savage races, such as the Australians, are not exposed to more diversified con- ditions than are many species which have very wide ranges. In another and much more important re- spect, man differs widely from any strictly domesti- cated animal ; for his breeding has not been controlled, either through methodical or unconscious selection. No race or body of men has been so completely subjugated by other men, that certain individuals have been pre- served and thus unconsciously selected, from being in some way more useful 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 grenadiers ; and in this case man obeyed, as might have been expected, the law of me- thodical selection ; for it is asserted that many tall men were reared in the villages inhabited by the grenadiers with their tall wives. 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 re- stricted 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 docs variability appear to be induced in man and the lower animals by the same general causes, but in both the same characters are affected in a closel) analogous manner. This has been proved in such fttH detail by Godron and Quatrefages, that I need here only refer to their works.13 Monstrosities, which gr®' 13 Godron, 1 De l’Espoce,’ 1859, tom. ii. livre 3. Quatrefages, 1 TTnite de l’Espece Humaine,’ 1861. Also Lectures on Anthropology, given in the ‘ Eevue des Cours Seientifiquos,’ 1866-18CS. Chap. IV. MANNER OF DEVELOPMENT. 113 duate into slight variations, are likewise so similar in man and the lower animals, that the same classifica- tion and the same terms can he used for both, as may be seen in Isidore Geoffrey St-IIilaire’s great work.14 This is a necessary consequence of the same laws of change prevailing throughout the animal kingdom. In my work on the variation of domestic animals, 1 have attempted to arrange in a rude fashion the laws of variation under the following heads -.—The direct and definite action of changed conditions, as shewn 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 uso or disuse of Parts. The cohesion of homologous parts. The vari- ability of multiple parts. Compensation of growth ; hut of this law I have found no good instances m the case of man. The effects of the mechanical pressure of °ne part on another ; as of the pelvis on the omnium 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 bo superfluous here to discuss all of them;15 but several are so im- portant for us, that they must be treated at consider- able length. The direct and definite action of changed conditions - This is a most perplexing subject. It cannot be denied 14 ‘Hist. Gen. et Part, des Anomalies de ^Organisation,4 in three volumes, tom. i. 1832. „ . L. ... , 15 I have fully discussed these laws in my ‘Variation of Animals an6. 156 THE DESCENT OF MAN. Part I. “ 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 little strength of man, his small speed in running, and his slight power of smell, by which to discover food or to avoid danger. To these deficiencies there might have been added the still more serious loss of the power of quickly climbing trees, so as to escape from enemies. Seeing that the unclothed Fuegians can exist under their wretched climate, the loss of hair would not have been a great injury to primeval man, if he inha- bited a warm country. When we compare defenceless man with the apes, many of which are provided with formidable canine teeth, we must remember that these in their fully-developed condition are possessed by the males alone, being chiefly used by them for fighting with their rivals; yet the females which are not thus provided, are able to survive. In regard to bodily size or strength, we do not know whether man is descended from some comparatively small species, like the chimpanzee, or from one as powerful as the gorilla ; and, therefore, we cannot say whether man ba3 become larger and stronger, or smaller and weaker, in comparison with his progenitors. We should, however, bear in mind that an animal possessing great size, strength, and ferocity, and which, like the gorilla, could defend itself from all enemies, would probably, though not necessarily, have tailed to become social ; and this would most effectually have checked the acquirement by man of his higher mental quali- ties, such as sympathy and the love of his fellow- creatures. Hence it might have been an immense Chap. IV. MANNER OE DEVELOPMENT. 157 advantage to man to have sprang from some com- paratively weak creature. The slight corporeal strength of man, his little speed, his want ot natural weapons, &c., are more than coun- terbalanced, firstly by his intellectual powers, through which ho has, whilst still remaining in a barbarous state, formed for himself weapons, tools, &c., and secondly by his social qualities which lead him to give aid to his fellow-men and to receive it in return. No country in the world abounds in a greater degree with dan- gerous beasts than Southern Africa; no country pre- sents more fearful physical hardships than the Arctic regions ; vet one of the puniest races, namely, the Bushmen, maintain themselves in Southern Airica, as do the dwarfed Esquimaux in the Arctic regions. Ihe early progenitors of man were, no doubt, inferior in intellect, and probably in social disposition, to the lowest existing savages ; but it is quite conceivable that they might have existed, or even flourished, if, whilst they gradually lost their brute-like powers, such as climbing trees, &c., they at the same time advanced in inteliect. But granting that the progenitors of man were far more helpless and defenceless than any existing savages, if they had inhabited some warm continent or large island, such as Australia or New Guinea, or Borneo (the latter island being now tenanted by t e orang), they would not have been exposed to any special danger. In an area as large as one of these islands, the competition between tribe and tribe would have been, sufficient, under favourable conditions, to have raised mail, through the survival ot the fittest, combined with the inherited effects of habit, to his present high position in the organic scale. 158 THE DESCENT OE MAN. Pakt I. CHAPTER Y. On the Development or the Intellectual and Moral Faculties during Primeval and Civilised Times. The 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. The subjects to be discussed in this chapter are of the liigliest interest, but are treated by me in a most imperfect and fragmentary manner. Mr. Wallace, in an admirable paper before referred to,1 argues that man after he had partially acquired those intellectual and moral faculties which distinguish him from the lower animals, would have been but little liable to have had his bodily structure modified through natural selection or any other means. For man is enabled through his mental faculties “to keep with an un- “ changed 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, by which he procures food and defends himself. When he migrates into a colder climate he uses clothes, builds sheds, and makes fires ; and, by the aid of fire, cooks food otherwise indigestible. He aids his fellow-men in many ways, and anticipates future events. Even at a remote period he practised some subdivision of labour. ‘ Anthropological Beview,’ May, 1S64, p. clviii. Chap. V. INTELLECTUAL FACULTIES. 159 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, in order to defend themselves from 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. The ease, however, is widely different, as Mr. Wal- lace has with justice insisted, in relation to the intel- lectual and moral faculties of man. These faculties are ' triable ; and we have every reason to believe that the ''ariations tend to bo inherited. Therefore, if they were formerly of high importance to primeval man and to l‘is ape-like progenitors, they would have been per- fected or advanced through natural selection. Of the high importance of the intellectual faculties there can he no doubt, for man mainly owes to them his pre- eminent position in the world. Wc can see that, in the rudest state of society, the individuals who were the most sagacious, who invented and used the best weapons 0r traps, and who were best able to defend themselves, "ronld rear the greatest number of offspring. The tribes "'hich included the largest number of men thus endowed "ould increase in number and supplant other tribes. ^Umbers depend primarily on the means of subsistence, aud this, partly on the physical nature of the country, Imt in a much higher degree ou the arts which are there practised. As a tribe increases and is victorious, it is °ften still further increased by the absorption of other tribes.2 The stature and strength of the men of a tribe After a time the members or tribes which are absorbed into another |Lbe assume, as Mr. Maine remarks (‘Ancient Law,’ 1861, p. 131), that ley we the co-descendants of the same ancestors. 160 THE DESCENT OF MAN. Pakt I- 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 more powerful and, judging from their sword- handles, larger-handed race;3 but their success was probably due in a much higher degree to their superiority in the arts. All that we know 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. Eelies 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 present 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 probable that with mankind the intellectual faculties have been gradually perfected through natural selection ; and this conclusion is sufficient for our purpose. Undoubtedly it would have been very interesting to have traced the development of each separate faculty from the state in which it exists in the lower animals to that in which d exists in man ; but neither my ability nor knowledge permit the attempt. It deserves notice that as soon as the progenitors of man became social (and this probably occurred at il very early period), the advancement of the intellectual faculties will have been aided and modified in an important manner, of which we see only traces 1 Morlot, 1 Soc. Vaud. Sc. Nat.’ I860, p. 294. Chap. V. INTELLECTUAL FACULTIES. 161 the lower animals, namely, through the principle of imitation, together with reason and experience. 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 hy experience, and imitate each others’ caution. Now, if some one man in a tribe, more sagacious than the others, invented a new snare or weapon, or other means °f 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 supplant other tribes. In a tribe thus rendered more numerous there Would always be a rather better 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 doeu ascertained by agriculturists4 that by preserving aod 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 progenitors °f man, should have become social, they must have 4 I have given instances in my ‘ Variation of Animals under Domes- “cation,’ vol. ii. p. 196. VOL. I. M 162 THE DESCENT OE MAN. Part I. acquired tlie same instinctive feelings which impel other animals to live in a body; and they no doubt exhi- bited 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 o the lower animals is disputed by no one, were no doubt 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 the one tribe included (other circumstances being' equal) a greater number of courageous, sympathetic, and faithful members, who were always ready to warn each other of danger, to aid and defend each other, this tribe would without doubt succeed best and conquer the other. Let it be borne in mind how all-important, i» the never-ceasing wars of savages, fidelity and courage must be. The advantage which disciplined soldiers have over undisciplined hordes follows chiefly from the confidence which each man feels in his comrades. Obedience, as Mr. Bagehot has well shewn,5 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 tribe possessing the above qualities in a high de- gree would spread and be victorious over other tribes ; hut in the course of time it would, judging from all past history, be in its turn overcome by some other 5 See a remarkable series of articles on Physics and Politics in the 1 Fortnightly Review,’ Nov. 1867; April 1, 1868; July 1, 1869. Chap. V. MORAL FACULTIES. 163 and still more highly endowed tribe. Thus the social and moral qualities would tend slowly to advance and he diffused throughout the world. But it may be asked, how within the limits oi the same tribe did a large number of members first become endowed with these social and moral qualities, and how was the standard of excellence raised ? It is extremely doubtful whether the offspring of the more sympathetic and benevolent parents, or ot those which "ere the most faithful to their comrades, would be reared in greater number than the children of selfish and treacherous parents of 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. Ihe bravest uien, 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 number than other men. I' herefore it seems scarcely possible (bearing in mind that we are not here speaking of one tribe being vic- torious over another) that the number of men gifted With such virtues, or that the standard of their excel- lence, could be increased through natural selection, that is, by the survival of the fittest. Although the circumstances which lead to an increase in the number of men 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 foresight of the members became improved, each man would soon learn from experience that if he aided his fellow-men, he would commonly receive aid in return. From this low motive he might acquire the habit ot aiding his fellows ; and the habit of performing benevolent actions certainly strengthens the feeling of sympathy, which gives the 164 THE DESCENT OF MAN. Part I. first impulse to benevolent actions. Habits, moreover, followed during many generations probably tend to be inherited. But there is another and much more powerful sti- mulus to the development of the social virtues, namely, the praise and the blame of our fellow-men. The love of approbation and the dread of infamy, as well as the bestowal of praise or blame, are primarily due, as we have seen in the third chapter, to the instinct of sym- pathy; and this instinct no doubt was originally acquired, like all the other social instincts, through natural selec- tion. At how early a period the progenitors of man, in the course of their development, became capable of feel- ing and being impelled by the praise or blame of their fellow-creatures, we cannot, of course, say. But it appears that even dogs appreciate 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 personal 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 ; but how far they experience remorse is doubtful. I was at first surprised that I could not re- collect any recorded instances of this feeling in savages ; and Sir J. Lubbock6 states that he knows of none. But if we banish from our minds all cases given in novels and plays and in death-bed confessions made to priests, I doubt whether many of us have actually witnessed remorse; though we may have often seen shame and contrition for smaller offences. Remorse is 6 • Origin of Civilisation,’ 1870, p. 265. Chap. V. MORAL FACULTIES. 165 a deeply hidden feeling. It is incredible 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,7 would not feel remorse in his inmost soul, though he might conceal it, if ho had failed in a duty which he held sacred. We may therefore conclude that primeval man, at a very remote period, would have been influenced by the praise and blame of his fellows. It is obvious, that the members of the same tribe would approve ol conduct which appeared to them to be for the general good, and "'ould reprobate that which appeared evil. To do good nnto 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 impor- tance during rude times of the love 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 °f others, yet was roused to such actions by a sense °f glory, would by his example excite the same wish for glory in other men, and would strengthen by exer- cise 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., "’hi ch 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 third chapter. Ultimately a highly complex sentiment, having its first origin in the 7 Mr. Wallace gives cases in liis £ Contributions to tlie Theory of ■Natural Selection/ 1870, p. 354. 166 THE DESCENT OF MAN. Part I. social instincts, largely guided by the approbation ot our fellow-men, ruled by reason, self-interest, and in later times by deep religious feelings, confirmed by instruction and habit, all combined, constitute our moral sense or conscience. It must not be forgotten that although a high stand- ard 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 advancement in the standard of morality and an increase in the number of well-endowed men will certainly give an immense advantage to one tribe over another. There can be no doubt that a tribe including many members who, from possessing in a high degree the spirit of patriotism, fidelity, obedience, courage, and sympathy, were always ready to give aid to each other and to sacrifice them- selves for the common good, would he victorious over most other tribes ; and this would be natural selection. At all times throughout tho world tribes have sup- planted other tribes ; and as morality is one element in their success, the standard of morality and the num- ber of well-endowed men' will thus everywhere 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 the normal rule 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, Air. Maine,8 “the greatest part of mankind has never 8 ‘Ancient Law,’ 1S61, p. 22. For Mr. Bugeliot’s remarks, ‘Fort- nightly Review,’ April 1, 1S68, p. 452. Chap. V. CIVILISED NATIONS. 167 “ shewn a particle of desire that its civil institutions “ should be improved.” Progress seems to depend ou many concurrent favourable conditions, far too complex to he followed out. But it has often been remarked, that a cool climate from leading to industry and the various arts has been highly favourable, or even indispensable for this end. 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 lierra 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 culti- vation of the ground ; and the first steps in cultivation Would probably result, as 1 have elsewhere shewn,9 from some such accident as the seeds ot 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 diffi- cult to be solved. Natural Selection as affecting Civilised Nations. In the last and present chapters I have considered the advancement of man from a former semi-human con- dition to his present state as a barbarian. But some remarks on the agency of natural selection on civilised nations mav be here worth adding. 1 his subject has been ably discussed by Mr. W. R. Greg,10 and previously 9 1 Tlie Variation of Animals and Plants under Domestication,’ vol. i. P. 309. 10 1 Fraser’s Magazine,’ Sept. 186S, p. 353. This article seems to have struck many persons, and has given rise to two remarkable essays 168 THE DESCENT OF MAN. Part I. by Mr. Wallace and Mr. Galton.11 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 men exert their utmost skill to save the life of every one to the last moment. There is reason to believe 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 ol 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 help- less is mainly an incidental result of the instinct of sympathy, which was originally acquired as part of the social instincts, but subsequently rendered, in the manner previously indicated, more tender and more widely diffused. Ivor could we check our sympathy, ii so urged by hard reason, without deterioration in the and a rejoinder in the * Spectator,1 Oct. 3rd and 17th 1868. It has also been discussed in the ‘ Q. Journal of Science,’ I860, p. 152, and by Mr. Lawson Tait in the ‘Dublin Q. Journal of Medical Science,’ Feb. 1869, and by Mr. K. Kay Lankester in his ‘ Comparative Longevity,’ 1S70, p. 128. Similar views appeared previously in the ‘Australasian,’ July Id, 1867. I have borrowed ideas from several of these writers. For Mr. Wallace, see ‘ Anthropolog. Keview,’ as before cited. Mr. Galton in ‘Macmillan’s Magazine,’ Aug. 1865, p. 318; also his great work, ‘ Hereditary Genius,’ 1870. Chap. v. CIVILISED NATIONS. 169 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 contingent benefit, with a certain and great present evil. Hence we must bear without complaining the undoubtedly bad effects of the weak surviving and propagating their kind ; but there appears to be at least one check in steady action, namely the weaker and inferior members of society not marrying so freely as the sound ; and this check might be inde- finitely increased, though this is more to be hoped foi than expected, by the weak in body or mind refraining from marriage. In all civilised countries man accumulates property and bequeaths it to his children. So that the children in the same country do not by any means start fair in the race for success. But this is far from an unmixed 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 are now everywhere extending, their range, so as to take the place °f the lower races. Nor does the moderate accumulation °f wealth interfere with the process of selection. When a poor man becomes rich, his children enter trades or Professions in which there is struggle enough, so that the able in body and mind succeed best. 1 he 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 progress of all kinds mainly depends, not to mention other and higher advantages. No doubt wealth when very great tends to convert men into useless drones, but their number is never large ; and some degree of elimi- 170 THE DESCENT OP MAN. Pakt X. nation here occurs, as we daily see rich men, who happen to be fools or profligate, squandering away all their wealth. Primogeniture with entailed estates is a more direct evil, though it may formerly have been a great advan- tage by the creation of a dominant class, and any government is better than anarchy. The eldest sons, though they may be weak in body or mind, generally marry, whilst the younger sons, however superior in these respects, do not so generally marry. Nor can worthless 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 generation after generation the more beautiful and charming women; and these must generally be healthy in body and active in mind. The evil con- sequences, such as they may be, of the continued pre- servation ol 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,12 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 supe- riority of any kind. Although civilisation thus checks in many ways the action of natural selection, it apparently favours, by means of improved food and the freedom from occa- sional hardships, the better development of the body. This may be inferred from civilised men having been 12 ‘Hereditary Genius,’ 1S70, p. 132-140. Chap. V. CIVILISED NATIONS. 171 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 expeditious. Even the great luxury of the rich can be tut little detrimental ; for the expectation of life of our aristocracy, at all ages and ol both sexes, is very little Inferior to that of healthy English lives in the lower classes.13 \\ o will now loot to the intellectual faculties alone. If in each grade of society the members weie divided into two equal bodies, the one including the intel- lectually 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 iu the standard of the intellectually able. But I do not Wish to assert that this tendency may not ho more than counterbalanced iu other ways, as by the multiplication of the reckless and improvident ; but even to such as these, ability must he some advantage. It has often been objected to views like the fore- going, that the most eminent men who have ever lived have left no offspring to inherit their great intellect. ■Mr. Galton says,14 “ I regret I am unable to solve the ‘ simple question whether, and how far, men and women 1 who are prodigies of genius are infertile. I have, how- 1 ever, shewn that men of eminence are by no means so. 13 See the fifth and sixth columns, compiled from good authorities, ia the table given in Mr. E. R. Lankester’s ‘ Comparative Longevity,’ ls~0, p. 115. 14 1 Hereditary Genius,’ 1870, p. 330. 172 THE DESCENT OF MAN. Part I. Great lawgivers, the founders of beneficent religions, 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.15 So it will be with the intellectual faculties, namely from the some- what more able men in each grade of society succeeding rather better than the less able, and consequently in- creasing in number, if not otherwise prevented. When in any nation the standard of intellect and the number of intellectual men have increased, we may expect from the law of the deviation from an average, as shewn by Mr. Galton, that prodigies of genius will appear some- what 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. Restless men who will not follow any steady occupation — and this relic of barbarism is a great check to civilisation16 — emigrate to newly-settled countries, where they prove useful pioneers. Intemperance is so highly destructive, that the expectation of life of the intemperate, at the age, for instance, of thirty, is only l.'l'S years ; whilst for the rural labourers of England at the same a°n it is 15 ‘ Origin of Species’ (fifth edition, 1SG3), p. 104. ls ‘Hereditary Genius,’ 1S70, p. 847. Chap. v. CIVILISED NATIONS. 173 4059 years.17 Profligate women bear few children, and profligate men rarely marry; both suffer 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 unim- portant 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, which occasionally without any assignable cause make their Appearance in families, may perhaps be reversions to a savage state, from which wre are not removed by very many generations. This view seems indeed recognised m the common expression that such men are the black sheep of the family. With civilised nations, as far as an advanced stand- ard of morality, and an increased number of fairly Well-endowed men are concerned, natural selection ap- parently effects but little; though the fundamental social instincts were 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 fellow-men — the strengthening of our sympathies by habit — example and imitation — reason — experience and even self-inte- rest— instruction during youth, and religious feelings. A most important obstacle in civilised countries to aw increase in the number of men of a superior class has been strongly urged by Mr. Greg and Mr. Galton,ls " E. Kay Lankester, ‘Comparative Longevity,’ 1870, p.115. The able of tli© intemperate is from Neison's ‘Vital Statistics.’ In regard to profligacy, sec Dr. Farr, “ Influence of Marriage on Mortality,” • Nat. Ass°c. for the Promotion of Social Science,’ 1S58. 18 ‘ Fraser’s Magazine,’ Sept. 1868, p. 353. ‘ Macmillan’s Magazine,’ Aug. 1865, p. 318. The Rev. F. W. Farrar (‘ Fraser’s Mag.,’ Aug. 1870, 0- 264) taUeB a different view. 174 THE DESCENT OF MAN. Paiu I. namely, the fact that the very poor and reckless, who are often degraded by vice, almost invariably 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,10 they produce 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 iucrease at a quicker rate than the provident and generally virtuous members. Or as Mr. Greg puts the case : “ The care- “ less, squalid, unaspiring Irishman multiplies like “ rabbits : the frugal, foreseeing, self-respecting, am- bitious Scot, stern in his morality, spiritual in his “faith, sagacious and disciplined 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 ot “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 less favoured race that had prevailed “ — 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 intemperate suffer 10 “On the Laws of the Fertility of Women,” in ‘Transact. Roj'h Soc.’ Edinburgh, vol. xxiv. p. 287. See, also, Mr. Galton, ‘ Hereditary Genius,’ p. 352-357, for observations to the above effect. Chap. V. CIVILISED NATIONS. 175 from a high rate of mortality, and tlie extremely pro- fligate 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,30 that at all ages the death-rate is higher in towns than in rural districts, “and during the first live years of life the town death- “ rate is almost exactly double that of the rural districts.” As these returns include both the rich and the poor, no doubt more than double the number of births would be requisite to keep up the number of the very poor inha- bitants in the towns, relatively to those in the country. M ith 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, ulso, of husbands under twenty is “ excessively high,” 21 hut 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 would be only slightly lessened. It was established from an enormous body of statistics, taken during 1853, that the unmarried men throughout Ifr'ance, between the ages of twenty and eighty, die in a ruuch larger proportion than the married : for instance, °ut of every 1000 unmarried men, between the ages of twenty and thirty, 11*3 annually died, whilst of the Carried only 6-5 died.22 A similar law was proved to 20 1 Tenth Annual Report of Births, Deaths, &c., in Scotland,’ 1S67, P' xxix. 21 These quotations are taken from our highest authority on such laestions, namely, Dr. Farr, in his paper “ On the Influence of Marriage ;’ri the Mortality of the French People,” read before the Nat. Assoc, ««* Promotion of Social Science, 1858. 22 Dr. Farr, ibid. The quotations given below are extracted from he same striking paper. 176 THE DESCENT OF MAN. Part I- hold good, during the years 1863 and 1861, 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 tho married only 7*21 died, that is less than half.23 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 tho 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 like- wise be admitted that men with a weak constitution, ill health, or any great infirmity in body or mind, will often not w ish to marry, or will be rejected. Dr. 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 advan- tage 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 therefore always with a lessened chance of life. There is another remarkable circum- stance 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 ; hut Dr. Farr attributes this to the poverty and 23 I have taken the mean of the quinquennial means, given in ‘ The Tenth Annual Roport of Births, Deaths, &c., in Scotland,’ 1867. The quotation from Dr. Stark is copied from an article in the ‘ Daily News, Oct. 17th, 1868, which Dr. Farr considers very carefully written. Chap. V. CIVILISED NATIONS. 177 evil habits consequent on the disruption of the family, and to grief. On the whole we may conclude with Dr. Farr that the lesser mortality of married than of unmar- ried 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, in- tellectual, 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 °f mortality. If the various checks specified in the two last para- graphs, and perhaps others as yet unknown, do not prevent the reckless, the vicious and otherwise inferior members of society from increasing at a quicker rate than the better class of men, the nation will retro- grade, as has occurred too often in the history of the "’or Id. We must remember that progress is no invari- aUe rule. It is most difficult to say why one civilised ration rises, becomes more powerful, and spreads more "’idely, than another; or why the same nation progresses more 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 'vith high intellectual and moral faculties, as well as 011 their standard of excellence. Corporeal structure, eXcept so far as vigour of body leads to vigour of mind, aPpears to have little influence. It has been urged by several writers that as high mtellectual powers are advantageous to a nation, the °hl Greeks, who stood some grades higher in intellect than any race that has ever existed,24 ought to have 14 See the ingenious and original argument on this subject by Mr. ahon, ‘ Hereditary Genius,’ p. 310-342. vOL. I. N 178 THE DESCENT OF MAN. Part I. risen, if the power of natural selection were real, 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 cir- cumstances. Natural selection acts only in a tentative manner. Individuals and races may have acquired certain 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” 26 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 this 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 perplexing problem. At this early period, as Mr. Galton26 has remarked, almost all the men of a gentle nature, those given to medi- tation or culture of the mind, had no refuge except m the bosom of the Church which demanded celibacy ; 25 Mr. Grog, ■ Fraser's Magazine,’ Sept. 1868, p. 357. 26 ‘Hereditary Genius,’ 1870, p. 357-359. The Eev. F. H. Farrar (‘ Fraser’s Mag.’, Aug. 1870, p. 257) advances arguments on the other side. Sir C. I, yell had already (‘Principles of Geology,’ vol. ii. 1^,K'‘ p. 489) called attention, in a striking passage, to the evil influence o the Holy Inquisition in having lowered, through selection, the genera standard of intelligence in Europe. Chap. y. CIVILISED NATIONS. 179 and this could hardly fail to have had a deteriorating mfluence 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 centuries at the rate of a thousand a year. The evil "Inch the Catholic Church has thus effected, though Ho doubt counterbalanced to a certain, perhaps large extent in other ways, is incalculable; nevertheless, Europe has progressed at an unparalleled rate. The remarkable success of the English as colonists °ver other European nations, which is well illustrated by comparing the progress of the Canadians of English and Erench extraction, has been ascribed to their “ daring “ and persistent energy ; ” but wbo can say how the English gained their energy. There is apparently much truth in the belief that the wonderful progress the United States, as well as the character of the People, are the results of natural selection ; the more energetic, restless, and courageous men from all parts °f Europe having emigrated during the last ten or twelve generations to that great country, and having there succeeded best.27 Looking to the distant future, I do Hot think that the Rev. Mr. Zincke takes an exaggerated view when he says :28 “ All other series of events— as ‘ that which resulted in the culture of mind in Greece, and that which resulted in the empire of Rome — only appear to have purpose and value when viewed in connection with, or rather as subsidiary to ... . the great stream of Anglo-Saxon emigration to the west.” 7 Mr. Galton, ‘ Macmillan’s Magazine,’ August, 18G5, p. 325. See a s°> ‘ Nature,’ “ On Darwinism and National Life,” Dee. 1869, p. 184. ‘ Last Winter in the United States,’ 1868, p. 29. N 2 180 THE DESCENT OF MAN. Part I- Obscure as is tbe 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 intel- lectual, energetic, brave, patriotic, and benevolent men, would generally prevail over less favoured nations. Natural selection follows from the struggle for exist- ence ; and this from a rapid rate of increase. It is impossible not bitterly to regret, but whether wisely is another question, the rate at which man tends to increase ; for this leads in barbarous tribes to infan- ticide and many other evils, and in civilised nations to abject poverty, celibacy, and to the late marriages of the prudent. But as man suffers from the same physical evils with the lower animals, he has no right to expect an immunity from the evils consequent on the struggle for existence. Had lie not been subjected to natural selection, assuredly he would never have attained to the rank of manhood. When we see in many parts of the world enormous areas of the most fertile land peopled by a few wandering savages, but which are capable of supporting numerous happy homes, it might be argued that the strugglo for existence had not been sufficiently severe to force man upwards to his highest standard. Judging from all that we know of man and the lower animals, there has always been sufficient variability in the intellectual and moral faculties, f°r their steady advancement through natural selection. No doubt such advancement 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 severe to an extreme degree. On the evidence that all civilised nations were once baf- barous. — As we have had to consider the steps by which Chap. V. CIVILISED NATIONS. 181 some semi-human creature has been gradually raised to the rank of man in his most perfect state, the present subject cannot be quite passed over. But it has been treated in so full and admirable a manner by Sir J. Lubbock,'29 Mr. Tylor, Mr. McLennan, and others, that I need here give oidy the briefest summary of their results. The arguments recently advanced by the Luke of Argyll 30 and formerly by Archbishop Whately, in favour of the belief that man came into the world us a civilised being and that all savages have since undergone degradation, seem to me weak in comparison "ith those advanced on the other side. Many nations, no doubt, have fallen away in civilisation, and some uiay have lapsed into utter barbarism, though on this latter head I have not met with any evidence. The Luegians were probably compelled by other conquering hordes to settle in their inhospitable country, and they ruay have become in consequence somewhat more degraded ; but it would be difficult to prove that they have fallen much below the Botocudos who inhabit the huest parts of Brazil. The evidence that all civilised nations are the de- fendants of barbarians, consists, on the one side, of °lear traces of their former low condition in still-existing °Ustoms, beliefs, language, &c. ; and on the other side, °f proofs that savages are independently 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, for instance, of the art of euumorat ion, which, as Mr. Tylor clearly shows by the "ords still used in some places, originated in counting 29 ‘ On the Origin of Civilisation,’ ‘ Proc. Ethnological Soc.’ Nov. ^6, 18G7. 39 ‘ Primeval Man,’ 1S69. 182 THE DESCENT OP MAN. Part l. 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 Roman numerals, which after reaching to the number V., change into VI., &c., when the other hand no doubt wTas used. So again, “ when we speak of three-score and ten, we are count- “ iug by the vigesimal system, each score thus ideally “ made, standing for 20 — for ‘ one man ’ as a Mexican “ or Carib would put it.” 31 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, as letters are rudiments of pictorial representations. It is hardly possible to read Mr. M‘Lennan’s work32 and not admit that almost all civilised nations still retain some 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 monogamous ? The primitive idea of justice, as shewn by the law of battle and other customs of which traces still remain, was likewise most rude. Many existing superstitions are the remnants of former false religious beliefs. Tho highest form of religion — the grand idea of God hating sin and loving righteousness — was unknown during primeval times. Turning to the other kind of evidence : Sir J. Lub- bock has shewn that some savages have recently ini' proved a little in some of their simpler arts. From the 31 ‘ Koval Institution of Great Britain,’ Marcli 15, 1867. Also, ‘ Researches into tho Early History of Mankind,’ 1865. 32 ‘ Primitive Marriage,’ 1S65. See, likewise, an excellent article, evidently ky the same author, in the ‘ North British Review,’ July, 1SG9. Also, Mr. L. H. Morgan, “ A Conjectural Solution of the Origin of the Class. System of Relationship,” in ‘ Proc. American Acad, of Sciences,’ vol. vii. Peb. 1868. Prof. Schaaffhausen (‘ Autliropolog- Review,’ Oct. 186!),- p. 373) remarks on “the vestiges of human sacri- “ fices found both in Homer aud the Old Testament.” Chap. V. CIVILISED NATIONS. 183 extremely curious account which he gives of the weapons, tools, and arts, used or practised by savages in various parts of the world, it cannot be doubted that these have nearly all been independent discoveries, excepting per- haps the art of making fire.33 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 any foreign source ; 34 many native plants were there cultivated, and a few Dative animals domesticated. We should bear in mind that a wandering crew from some semi-civilised land, if washed to the shores of America, would not, judging from the small influence of most missionaries, have pro- duced any marked effect 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 Dse 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. fa all parts of Europe, as far east as Greece, in Palestine, India, Japan, New Zealand, and Africa, including Egypt, flint tools have been discovered in abundance; and oi their use the existing inhabitants retain no tradition. There is also indirect evidence of their former use by the Chinese and ancient Jews. Hence there can hardly be a floubt that the inhabitants of these many countries, which include nearly the whole civilised world, were once in a barbarous condition. To believe that man was abori- 33 Sir J. Lubbock, * Prehistoric Times,’ 2nd edit. 1869, chap. xv. and Xvt et passim. 34 Dr. P, Muller has made some good remarks to this effect in the ‘ Reise del- Novara : Anthropolog. Theil,’ Abtheil. iii. 18G8, s. 127. 184 THE DESCENT OF MAN. Part I. 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 religion. AFFINITIES AND GENEALOGY. 185 Ohaj>. VI. j CHAPTEK YI. 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 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 iulerrcd, firstly irom his affinities and secondly from his structure — Early androgynous condition of the Yertebrata — Conclusion. Even if it be granted that the difference between man ^d bis nearest allies is as great in corporeal structure as some naturalists maintain, and although we must grant that the difference between them is immense in mental Power, yet the facts given in the previous chapters declare, as it appears to me, in the plainest manner, that man is descended from some lower form, notwith- standing that connecting-links have not hitherto been discovered. Man is liable to numerous, slight, and diversified variations, which are induced by the same general causes, are governed and transmitted in accordance "ith the same general laws, as in the lower animals. Man tends to multiply at so rapid a rate that his off- spring are necessarily exposed to a struggle tor existence, and consequently to natural selection. He 1ms given Hse to many races, some of which are so different that they have often been ranked by naturalists as distinct species. His body is constructed on the same homo- logical plan as that of other mammals, independently of the uses to which the several parts may he put. He 186 THE DESCENT OP MAN. Part L passes through the same phases of embryological de- velopment. He retains many rudimentary and useless structures, which no doubt were once serviceable. Cha- racters occasionally make their re-appearance in him, which we have every 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 appearances, on the other hand, are intelligible, at least to a large extent, if man is the co-descendant with other mammals of some unknown and lower form. Some naturalists, 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, and the Vegetable, thus giving to man a separate kingdom.1 Spiritual powers cannot be com- pared or classed by the naturalist ; but he may endea- vour 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 powers of two insects, namely, a coccus or scale-insect and an ant, which undoubt- edly belong to the same class. The difference is here greater, though of a somewhat different kind, than that between man and the highest mammal. The female coccus, whilst young, attaches itself by its pro- boscis 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 1 Isidore Geoffroy St.-Hilaire gives a detailed account of the position assigned to man by various naturalists in their classifications : ‘ Hist* Nat. Gen.’ tom. ii. 1859, p. 170-1S9. Chap. VI. AFFINITIES AND GENEALOGY. 187 powers of a female ant, would require, as Pierre Huber bas shewn, a large volume; I may, however, briefly specify a few points. Ants communicate information to each other, and several unite for the same work, or games of play. They recognise their fellow-ants after months of absence. They build great edifices, keep them clean, close the doors in tbe evening, and post sentries. They make roads, and even tunnels under rivers. 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.2 They go out to battle in regular bands, and freely sacrifice their lives for the common Weal. They emigrate in accordance with a precon- certed plan. They capture slaves. They keep Aphides as milch-cows. 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 them in distinct classes, much less in distinct kingdoms. No doubt this interval is bridged over by the intermediate mental powers of many other insects ; and this is not the case with man and the higher apes. But we have every reason to believe that breaks in the series are simply the result of many forms having be- come 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 be places both the marsupials and the monotremata ; so that he makes man as distinct from all other mam- 2 See the very interesting article, u L’Instinct chez les Insectes,” by George Pouohet, ‘ Kevue des Deux Mondes,’ Feb. 1870, p. 682. 188 THE DESCENT OP MAN. Part I. mals 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 judg- ment, and therefore need not here be further con- sidered. We can understand why a classification founded on any single character or organ — even an organ so won- derfully 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 arrangement proved thoroughly artificial.3 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 ol tire same form must be kept together in one group, separate from the co-descendants of any other form ; but if the parent-forms are related, so will be their descendants, and the two groups together will form a larger group. The amount of difference between the several groups — that is the amount of modification which each has undergone — will be expressed by such terms as genera, families, orders, and classes. As we have no record of the lines of descent, these lines can be discovered only by observing the degrees of re- semblance between the beings which are to be classed. For this object numerous points of resemblance 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 Westwood, * Modern Class, of Insects,’ vol. ii. 1810, p. 87. Chap. VI. AFFINITIES AND GENEALOGY. 189 words and points of construction, they would be uni- versally 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 con- sist of adaptations to similar habits of life : two animals may, for instance, have had their whole frames modified for living in the water, and yet they will not be brought any nearer to each other in the natural system. Hence We can see how it is that resemblances in unimportant structures, in useless and rudimentary organs, and in parts not as yet fully developed or functionally active, are by far the most serviceable for classification; 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 great amount of modifi- cation 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 lias 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 continually augmented. In many cases the continued development of a part, for instance, ot the beak of a bird, or of the teeth of a mammal, would not be advan- tageous to the species for gaining its food, or for any ether object ; hut with man we can see no definite limit, as far as advantage is concerned, to the continued de- velopment of the brain and mental faculties, therefore in determining the position of man in the natural or genealogical system, the extreme development of his brain ought not to outweigh a multitude of resem- 190 THE DESCENT OP MAN. Part I. blances in other less important or quite unimportant points. The greater number of naturalists who have taken into consideration 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 Biman a, 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 Linnreus, 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 if, in the first place, wo bear in mind the remarks just made on the comparatively small importance for classi- fication of the great development of the brain in man ; bearing, also, in mind that the strongly-marked differ- ences between the skulls ol man and the 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 differences between man and the Quadrumana are manifestly adaptive in their nature, and relate chiefly to the erect position of man ; such as the structure of his hand, foot, 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 than does man from the higher apes ; yet in every system, from that of Cuvier to the most recent one by Mr. Flower,4 seals are ranked as a mere family * ‘ Proo. Zoolog. Soo.’ 1869, p. 4. Chap. YI. AFFINITIES AND GENEALOGY. 191 111 the Order of the Carnivora. If man had not been his own classifier, lie 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 philosopher. Prof. Huxley, has fully discussed this subject.5 and lias come to the con- clusion that man in all parts of his organisation differs less from the higher apes, than these do from the lower uiembers of the same group. Consequently there “ is “ no justification for placing man in a distinct order.” In an early part of this volume I brought forward Various facts, shewing how closely man agrees in con- 8titution with the higher mammals ; and this agreement, Uo doubt, depends on our close similarity in minute structure and chemical composition. I gave, as ^stances, our liability to the same diseases, and to the uttaclcs of allied parasites ; our tastes in common for the 8atne stimulants, and the similar effects thus produced, as Well as by various drugs ; and other such facts. As small unimportant points of resemblance between 111 fui and the higher apes are not commonly noticed in 8ystematic works, and as, when numerous, they clearly I’cveal our relationship, I will specify a few such points. Ike relative position of the features is manifestly the sa®e in man and the Quadrumana; and the various eiUotions are displayed by nearly similar movements of *he muscles and skin, chiefly above the eyebrows and '"’•'id the mouth. Some few expressions are, indeed, aVost the same, as in the weeping of certain kinds of ’"°nkeys, and in the laughing noise made by others. ' Ul'ing which the corners of the mouth are drawn back- ‘ Evidence as to Man’s Place in Nature,’ 1863, p. 70, et passim. 192 THE DESCENT OF MAH. Part I- wards, and the lower eyelids wrinkled. The external ears are curiously alike. In man the nose is much more prominent than in most monkeys ; hut we may trace the commencement of an aquiline curvature in the nose of the Hoolock Gibbon ; and this in the Sem- nopithecus nasioa, 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 length in some species of Semno- pithecus ; 6 and in the Bonnet monkey ( Macacus radiatus) it radiates from a point on the crown, with a parting down the middle, as in man. It is commonly said that the forehead gives to man his noble and intel- lectual appearance ; but the thick hair on the head of the Bonnet monkey terminates abruptly downwards, and is succeeded by such short and fine hair, or down, that at a little distance the forehead, with the exception of the eyebrows, appears quite naked. It lias 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 states7 that in our children the lin'd between the hairy scalp and the naked forehead 18 9 sometimes not well defined ; so that here we seem to have a trifling case of reversion to a progenitor, in whom the forehead had not as yet become quite naked. It is well known that tho hair on our arms tends to converge from above and below to a point at the el bo" • This 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 Hylobates agilis the ha" 8 Isid. Geoffroy, ‘ Hist. Nat. Gen.’ tom. ii. 1850, p. 217. ’ “ Ueber die Kichtung der Haare,” &c., Muller’s ‘ Areliiv fiir Ana und Phys.’ 1837, s. 51. Chap. yi. AFFINITIES AND GENEALOGY. 193 °u the fore-arm is directed downwards or towards the "'list in the ordinary manner ; and in II. lar it is nearly G1’ect, 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 and its direction on the back is "dapted to throw off the rain ; even the transverse hairs °n the fore-legs of a dog may serve for this end when he is coiled up asleep. Mr, Wallace remarks that the con- vergence of the hair towards the elbow on the arms of the oraug (whose habits he has so carefully studied) serves to throw off the rain, when, as is the custom °I this animal, the arms are bent, with the hands "lasped round a branch or over its own head. We should, however, bear in mind that the attitude of an auiinal may perhaps be in part determined by the direction of the hair ; and not the direction of the hair h}’ the attitude. If the above explanation is correct in ihe case of the orang, the hair on our fore-arms offers a ""lions record of our former state ; for no one supposes that it is now of any use in throwing off the rain, nor in °1"' present 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 early progenitors ; for it is impossible to study the figures given by Eschrickt of the arrange- ment of the hair on the human foetus (this being the 8a®e 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 111 some relation to those points in the embryo which ai'e last closed in during development. There appears, als°, to exist some relation between the arrangement VOL. I. 0 191 THE DESCENT OF MAN. Part X. of the hair on the limbs, and the course of the medullary arteries.8 It must not be supposed that the resemblances be- tween 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 pro- genitor thus characterised, or of subsequent reversion. Many of these resemblances are more probably due to analogous variation, which follows, as I have else- where attempted to shew,8 from co-descended organisms having a similar constitution and having been acted on by similar causes inducing variability. With re- spect 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 inheritance; but not certainly so, as some very distinct American monkeys are thus characterised. The same remark is applicable to the tailless condition of man ; for the tail is absent in all the anthropomorphous apes. Nevertheless this character cannot with certainty be attributed to inheri- tance, as the tail, though not absent, is rudimentary in several other Old World and in some New World species, and is quite absent iu several species belonging to the allied group of Lemurs. Although, as we have now seen, man has no just right to form a separate Order for his own reception, he m»V 8 On the hair in Hylobates, see ‘ Nat. Hist, of Mammals,’ hy 0- h- Martin, 1841, p. 415. Also, Isul. Geoffroy on the American monkey® and other kinds, ‘Hist. Nat. Gen.’ vol. ii. 1859, p. 216, 243. Bsch richt, ibid, s. 46, 55, 61. Owen, ‘ Anat. of Vertebrates,’ vol. iii. P- Wallace, ‘ Contributions to the Theory of Natural Selection,’ 1870, !’■ 344. _ . * ‘ Origin of Species,’ 5th edit. 1869, p. 194. ‘ The Variation 0 Animals and Plants under Domestication,’ vol. ii. 1868, p. 348. Chap. VI. AFFINITIES AND GENEALOGY. 195 perhaps claim a distinct Sub-order or Family. Prof. Huxley, in his last work,10 divides the Primates into three Sub-orders ; namely, the Anthropidae with man ■'done, the Simiadge including monkeys of all kinds, and t^e Lemuridae 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 Iank of a Sub-order ; and this rank is too low, if we look ehiefly to his mental faculties. Nevertheless, under a genealogical point of view it appears that this rank is too high, and that man ought to form merely a Family, °v possibly even only a Sub-family. If we imagine three lines of descent proceeding from a common source, Jt is quite conceivable that two of them might after the lapse of ages be so slightly changed as still to I'ornain as species of the same genus; whilst the third hre might become so greatly modified as to deserve t° 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 witli the other t'vo lines. Here then would occur the difficulty, at present insoluble, how much weight we ought to assign our classifications to strongly-marked differences in ^°:ne few points, — that is to the amount of modification Undergone; and how much to close resemblance in Numerous unimportant points, as indicating the lines of descent or genealogy. The former alternative is the lllost obvious, and perhaps the safest, though the latter appears the most correct as giving a truly natural Hassification. -lo torm a judgment on this head, with reference 0 Qlan we must glance at the classification of the ‘ An Introduction to the Classification of Animals,’ 1863, p. 99. o 2 196' THE DESCENT OF MAN. Part I. Simiadse. This family is divided by almost all natura- lists into the Catarhine group, or Old World monkeys, all of which are characterised (as their name expresses) by the peculiar structure of their nostrils and by having four premolars in each jaw; and into the Platvrhine group or New World monkeys (including two very distinct sub-groups), all of which are characterised by differently-constructed nostrils and by having six pre- molars 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. Therefore it would be against all probability to suppose that some ancient New World species had varied, and had thus 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 offshoot from the Old World Simian stem : and that under a genealogical point of view, he must be classed with the Catarhine division.11 The anthropomoi-phous apes, namely the gorilla- chimpanzee, orang, and hylobates, are separated as a distinct sub-group from the other Old World monkeys by most naturalists. I am aware that Gratiolet, relying on the structure of the brain, does not admit the exist- 11 This is nearly the same classification as that provisionally adopted by Mr. St. George Mivart (‘ Transact. Philosoph. Soc.’ 1S67, p. 300), who, after separating the Lemuridre, divides the remainder of the Primates into the Hominidse, the Simiadse answering to the Catarhine-1 the Cebidse, and the Hapalidas, — these two latter groups answering to the Platyrhines. Chap. VI. AFFINITIES AND GENEALOGY. 197 ence of this sub-group, and no doubt it is a broken ; thus the orang, as Mr. St. G. Mivart' remarks,12 ‘ is one of the most peculiar and aberrant forms to be “ iound in the Order.” The remaining, non-anthropo- ^orphous, Old World monkeys, are again divided by some naturalists into two or three smaller sub-groups ; the genus Semnopithecus, with its peculiar sacculated stomach, being the type of one such sub-group. But appears from M. Gaudry’s wonderful discoveries in Attica, that during the Miocene period a form existed there, which connected Semnopithecus and Macacus; a,id this probably illustrates the manner in which the °ther and higher groups were once blended together. If the anthropomorphous apes be admitted to form a natural sub-group, then as man agrees with them, Hot only in all those characters which he possesses in common with the whole Catarhine group, but in other Peculiar characters, such as the absence of a tail and °f callosities and in general appearance, we may infer Ihat some ancient member of the anthropomorphous sub-group gave birth to man. It is not probable *hut a member of one of the other lower sub-groups should, through the law of analogous variation, have §lven rise to a man-like creature, resembling the higher Hothropomorphous apes in so many respects. No houbt man, in comparison with most of his allies, has Undergone an extraordinary amount of modification, chiefly in consequence of his greatly developed brain ail(t erect position ; nevertheless we should bear in 111 hid that be “ is but one of several exceptional forms “ of Primates.”13 livery naturalist, who believes iu the principle of 12 ‘ Transact. Zoolog. Soc.’ vol, vi. 1867, p. 214. 13 Mr. St. G. Mivart, ‘ Transact. Phil. Soc.’ 1867, p. 410. 198 THE DESCENT OF MAN. Part !• evolution, will grant that the two main divisions of the Siiuiadse, namely the Catarhine and Platyrhine mon- keys, 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 incipient genera would have already begun to indicate by their diverging characters the future distinctive marks of the Catarhine and Platyrhine divi- sions. Hence the members of this supposed ancient group would not have been so uniform in their dentition or in the structure of their nostrils, as are the existing Catarhine monkeys in one way and the Platyrhines m another way, but would have resembled in this respect the allied Lenin rid te which differ greatly from each other in the form of their muzzles,1,1 and to an extra- ordinary degree in their dentition. The Catarhine and Platyrhine monkeys agree m a multitude of characters, as is shewn by their unques- tionably 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 an ancient form which possesse many characters common to the Catarhine and Plat)' rhine monkeys, and others in an intermediate condition* and some few perhaps distinct from those now present in either group, would undoubtedly have been ranked, if seen by a naturalist, as an ape or monkey. And as man under a genealogical point of view belongs to tin Catarhine or Old World stock, we must conclude, ho"' 14 Messrs. Mine and Mivart on the Lemuroidea, ‘Transact. Zoolon Soc.’ vol. vii. 1869, p. 5. Chap. VI. AFFINITIES AND GENEALOGY. 199 ever much the conclusion may revolt our pride, that our early progenitors would have been properly thus designated.16 But we must not fall into the error of supposing that the early progenitor of the whole Simian stock, including man, was identical with, or even closely Resembled, any existing ape or monkey. On the Birthplace and Antiquity of Man. li e 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 lact 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 geogra- phical distribution. In each great region of the world the living mammals are closely related to the extinct species of the same region. It is therefore probable that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee ; 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 an ape Dearly as large as a man, namely the Dryopithecus ol Lartet, which was closely allied to the anthropo- morphous Hylobates, existed in Europe during the Upper Miocene period ; and since so remote a period the earth has certainly undergone many great revo- lutions, and there has been ample time for migration °u the largest scale. 13 ITackel lias come to tliis same conclusion. See 4 Ucber die Ent- stehung des Menschengeschleehts,’ in Virchow’s 4 Sammlimg. gemein. wissen. Vortrage.’ 1868, s. 01. Also his 4 Natiirliche Schopfungs- Seschichte,’ 1868^ in which he gives in detail his views on the genea- logy of man. 200 THE DESCENT OF MAN. Past I- At the period and place, whenever and wherever it may have been, when man first lost his hairy covering, he probably inhabited a hot country; and this would have been favourable for a frugiferous diet, on which, judging from analogy, he subsisted. We are far from knowing how long ago it was when man first diverged from the Catarhine stock ; but this may have occurred at an epoch as remote as the Eocene period; for the higher apes had diverged from the lower apes as early as the Upper Miocene period, as shewn by the existence of the Dryopithecus. We are also quite ignorant at how rapid a rate organisms, whether high or low in the scale, may under favourable circumstances be modified : wre 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 within the same period some of the co-descendants of the same species may be not at all changed, some a little, and some greatly changed. Thus it may have been with man, who has undergone a great amount ot 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 ad- vanced 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, convinced by general reasons, believe in the general principl® of evolution. Breaks incessantly 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 — between the Tarsius and the other Lemuridse — between the elephant and in a more striking manner between the Ornithorhynchus or Chap. VI. AFFINITIES AND GENEALOGY. 201 Echidna, and other mammals. But all 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 throughout the world the savage races. At the same time the anthropomorphous apes, as Professor Schaaffhausen has remarked,16 will no doubt be exter- minated. The break will then be rendered wider, for it will intervene between man in a more civilised state, as we may hope, than the Caucasian, and some ape as low as a baboon, instead of as at present between the negro or Australian and the gorilla. 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 will read Sir C. Lyell’s discussion,1' in which he shews that in all the vertebrate classes the discovery of fossil remains has been an extremely slow and fortuitous process. Nor should it be forgotten that those regions which are the most likely 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 JKan. We have seen that man appears to have diverged from the Oatarliine or Old World division of the SimiadcB, alter these had diverged from the New World division. We will now endeavour to follow the more remote traces of his genealogy, trusting in the first place to the mutual affinities between the various classes and orders, with sonre slight aid from the periods, as far as ascertained, 18 ‘Anthropological Keview,’ April, 1SG7, p. 23G. 17 ‘Elements of Geology,’ 1865, p. 583-585. ‘Antiquity of Man, 1863, p. H5. 202 THE DESCENT OF MAN. Part I- of their successive appearance on the earth. The Lemuridse stand below and close to the Siraiadse, con- stituting a very distinct family of the Primates, or, according to Haekel, a distinct Order. This group is diversified and broken to an extraordinary degree, and includes many aberrant forms. It has, therefore, pro- bably suffered much extinction. Most of the remnants survive on islands, namely in Madagascar and in the islands of the Malayan archipelago, where they have not been exposed to such severe competition as they would have been on well-stocked continents. This group likewise presents many gradations, leading, as Huxley remarks,18 “ insensibly from the croivn 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 Simiadm were originally developed from the progenitors of the existing Lemuridse ; 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 what it nowr is. Hence the Placentata are generally supposed to have been derived from the I m placentata or Marsupials ; not, however, fro® forms closely like the existing Marsupials, but fro® their early progenitors. The Monotrcmata are plainly allied to the Marsupials ; forming a third and still lower division in the great mammalian series. They are represented at the present day solely by the Or®' thorhynchus and Echidna ; and these two forms may 18 1 Man’s Place in Nature,’ p. 105. Chap. VI. AFFINITIES AND GENEALOGY. 203 be safely considered as relics of a much larger group ■which have been preserved in Australia through some favourable concurrence of circumstances. The Mono- tremata are eminently interesting, as in several important points of structure they lead towards the class of reptiles. In attempting to trace the genealogy of the Mam- malia, and therefore of man, lower down in the series, we become involved in greater and greater obscurity. He who wishes to see what ingenuity and knowledge can effect, may consult Prof. Hackel’s works.19 I will content myself with a few general remarks. Every evolutionist will admit that the live great vertebrate classes, namely, mammals, birds, reptiles, amphibians, and fishes, are all 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 king- dom are derived from some fish-like animal, less highly organised than any as yet found in the lowest known formations. The belief that animals so distinct as a monkey or elephant and a humming-bird, a snake, frog, and 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. 1 or fids belief implies the former existence of links closely binding together all these forms, now so utterly unlike. 19 Elaborate tables nni given in his ‘Generellc Morpliologie (B. ii. eliii. and s. 425) ; and with more especial reference to man in his Yu, lirliche Sohopfungsgescbiohte,’ 1S68. Prof. Huxley, in reviewing this latter work (‘The Academy,’ 1869, p. 42) says, that he considers the phylum or lines of descent of the Vertebrata to be admirably dis- eased by Hiiekel, although he differs on some points. He expresses, al»o. his high estimate of the value of the general tenor and spirit of the whole work. 204 THE DESCENT OP MAN. Pakt I. Nevertheless it is certain that groups of animals have existed, or do now exist, which serve to connect more or less closely the several great vertebrate classes. We have seen that the Ornithorhynchus graduates towards reptiles ; and Prof. Huxley has made the remarkable discovery, confirmed by Mr. Cope and others, that the old Dinosaurians are intermediate in many important respects between certain reptiles and certain birds — the latter consisting of the ostrich-tribe (itself evidently a widely-diffused remnant of a larger group) and of the Archeopteryx, that strange Secondary bird having a long tail like that of the lizard. Again, according to Prof. Owen,20 the Iehthyosaurians — great sea-lizards fur- nished with paddles — present many affinities with fishes, or rather, according to Huxley, with amphibians. This latter class (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 highly generalised type, that is they presented diversified "affi- nities with other groups of organisms. The amphibians and fishes are also so closely united by the Lepidosiren, that naturalists long disputed in which of these two classes it ought to be placed. The Lepidosiren arid some few Ganoid fishes have been preserved from utter extinction by inhabiting our rivers, which are harbours of refuge, bearing the same relation to the great waters of the ocean that islands bear to continents. Lastly, one single member of the immense and diver- sified class of fishes, namely the lancelet or amphioxus, is so different from all other fishes, that Hackel main- tains that it ought to form a distinct class in the vertebrate kingdom. This fish is remarkable for its 20 ‘ Palaeontology,’ 1860, p. 199. Chap. VI. AFFINITIES AND GENEALOGY. 205 Negative characters ; it can hardly be said to possess a brain, vertebral column, or heart, &c. ; so that it was classed bv the older naturalists amongst the worms. Many years ago Prof. Goodsir perceived that the lancelet presented some affinities with the Ascidians, "hi cl i are invertebrate, hermaphrodite, marine crea- tures 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 naturalists amongst the Kermes or worms. Their larvae somewhat resemble tadpoles in shape,21 and have the power of swimming freely about. Some observations lately made by M. Kovalevsky,22 since confirmed by Prof. Kuppfer, will f°nn a discovery of extraordinary interest, if still further extended, as I hear from M. Kowalevsky in Naples he bas now effected. The discovery is that the larvae of Kscidians arc related to the Yertebrata, in their manner °f development, in the relative position of the nervous system, and in possessing a structure closely like the chorda dorsalis of vertebrate animals. It thus appears, b we may rely on embryology, which has always proved fhe safest guide in classification, that we have at last gained a clue to the source whence the Yertebrata have 21 I had the satisfaction of seeing, at the Falkland Islauda, in April, ^33, and therefore some years before any other naturalist, the loco- Motive larvre of a compound Ascidian, closely allied to, but apparently genetically distinct from, Synoicum. The tail 'was about five times as r,tlg as the oblong head, and terminated in a very tine filament. It )Vas plainly divided, as sketched by me under a simple microscope, by fans verse opaque partitions, which I presume represent the groat cells gured by Kowalevsky. At on early stage of development the tail was el°sely coiled round the head of the larva. “ ‘Memoires de l’Acad. des Sciences de St. PeTershourg,’ tom. x. No- 15, 1866. 206 THE DESCENT OF MAN. Part I. been derived. We should thus 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 affinities. We will now look to man as he exists ; and we shall, I think, be able partially to restore during successive periods, but not in due order of time, the structure of our early progenitors. This can be effected by means of the rudiments which man still retains, by the characters which occasionally make their appear- ance in him through reversion, and by the aid of the 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 were no doubt once covered with hail-, both sexes having beards ; their ears were pointed and capable of movement ; and their bodies were provided with a tail having the proper muscles. Their limbs and bodies were also acted on by many muscles which no"' only occasionally reappear, but are normally present in the Quadrumana. The great artery and nerve of the humerus ran through a supra-condyloid foramen. At this or some earlier period, the intestine gave forth a much larger diverticulum or caecum than that now existing. The foot, judging from the condition of the great toe in the foetus, was then prehensile; and our progenitors, no doubt, were arboreal in their habits, frequenting some warm, forest-clad land. The males Chap. VI. AFFINITIES AND GENEALOGY. 207 Were provided with, great canine teeth, which served them as formidable weapons. At a much 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 morpho- logy 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 bran- chiae once existed. At about this period the true kid- neys 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 predecessors of man, thus seen in the dim recesses °t time, must have been as lowly organised as the lance- Ict or amphioxus, or even still more lowly organised. There is one other point deserving a fuller notice, bt has long been known that in the vertebrate king- i o o c*om one sex hears rudiments of various accessory Parts, appertaining to the reproductive system, which Properly belong to the opposite sex; and it lias now been ascertained that at a very early embryonic period both sexes possess true male and female glands. Hence S0)ne extremely remote progenitor of the whole verte- brate kingdom appears to have been hermaphrodite or androgynous.23 Hut here we encounter a singular difficulty. In the mammalian class the males possess 21 This is the conclusion of one of the Highest authorities in com- parative auatomy, namely, Prof. Gegenbaur : ‘Grnndziige dor vergleich. y1(lh 1871), g. 876. The result lias been arrived at chiefly from the s udy of the Amphibia ; but it appears from the researches of Waldeyer hls quoted in Humphry’s ‘ Journal of Auat. and Phys.’ 1869, p. 161), ,, t the sexual organs of even “ the higher vertebrata are, in tlieir early c°ndition, hermaphrodite.” Similar views have long been hold by s°tnc authors, though until recently not well based. 208 THE DESCENT OF MAN. Part I. in their vesiculte prostraticae rudiments of a uterus with the adjacent passage ; they bear also rudiments of mammae, and some male marsupials have rudiments of a marsupial sack.24 Other analogous facts could be added. Are we, then, to suppose that some extremely ancient mammal possessed organs proper to both sexes, that is, continued androgynous after it had acquired the chief distinctions of its proper class, and therefore after it had diverged from the lower classes of the vertebrate kingdom ? This seems improbable in the highest degree; for had this been the case, we might have expected that some few members of the two lower classes, namely fishes25 and amphibians, would still have remained androgynous. We must, on the contrary, believe that when the five vertebrate classes diverged from their common progenitor the sexes had already become separated. To account, however, for male mammals possessing rudiments of the acces- sory female organs, and for female mammals possessing rudiments of the masculine organs, we need not suppose that their early progenitors were still androgynous after they had assumed their chief mammalian characters. It is quite possible that as the one sex gradually acquired the accessory organs proper to it, some of the successive steps or modifications were transmitted to the opposite sex. 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, 2< The male Thylocinus offers the best instance. Owen, ‘ Anatomy of Vertebrates,’ vol. iii. p. 771. 25 Serranus is well known often to bo in an hermaphrodite condition with the organs proper to both sexes symmetrically developed. Several excellent naturalists are convinced that this is the normal condition , hut Dr. Gunther, as he informs me, does not believe that tiffs is the case. Descent from an ancient androgynous prototype would, however, naturally favour and explain, to u certain extent, the frequent recur- rence in these fishes of this condition, if it be abnormal. Chap. VI. AFFINITIES AND GENEALOGY. 209 and brilliant colours, acquired by male birds for battle or ornament, and transferred to the females in an im- perfect or rudimentary condition. The possession by male mammals of functionally ^perfect mammary organs is, in some respects, espe- cially curious. The Monotremata have the proper milk- secreting glands with orifices, but no nipples; and as ^ese animals stand at the very base of the mam- malian series, it is probable that the progenitors of the class possessed, in like manner, the milk-secreting glands, but no nipples. This conclusion is supported hy what is known of their manner of development; Idr Professor Turner informs me, on the authority of Rulliker and Langer, that in the embryo the mammary glands can be distinctly traced before the nipples are m the least visible ; and it should be borne in mind that the development of successive parts in the individual generally seems to represent and accord with the deve- lopment of successive beiugs in the same line of descent. .1 he Marsupials differ from the Monotremata by possess- lng nipples; so that these organs wore probably first Required by the Marsupials after they had diverged lr°m, and risen above, the Monotremata, and were ^cn transmitted to the placental mammals. No one "Hi suppose that after the Marsupials had approxi- mately acquired their present structure, and therefore at a rather late period in the development of the mammalian series, any of its members still remained Androgynous. We seem, therefore, compelled to recur to the foregoing view, and to conclude that the nipples ’"’ere first developed in the females of some very early marsupial form, and were then, in accordance with a Common law of inheritance, transferred in a functionally miperfect condition to the males. Nevertheless a suspicion has sometimes crossed my VOL. i. P 210 THE DESCENT OP MAN. Part I. mind that long after the progenitors of the whole mammalian class had ceased to be androgynous, both sexes might have yielded milk and thus nourished their young; and in the case of the Marsupials, that both sexes might have carried their young in mar- supial sacks. This will not appear utterly incredible, if we reflect that the males of svngnathous fishes receive the eggs of the females in their abdominal pouches, hatch them, and afterwards, as some believe, nourish the young;26 — that certain other male fishes hatch the 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, keep- ing them there until the tadpoles are born ; — that cer- tain 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 suspicion first occurred to me from the mammary glands in male mammals being developed so much more perfectly than the rudiments of those 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 simply not fully developed and not functionally active. They are sympathetically affected under the influence of certain diseases, like the same organs in the female. At birth they often secrete a few' drops of milk ; and they have 2,1 Mr. Lockwood believes (as quoted in ‘ Quart. Journal of Science.’ April, 1868, p. 269), from what he lias observed of the development of Hippocampus, that the walls of the abdominal pouch of the male in some way afford nourishment. On male Jishes hatching the ova W their mouths, see a very interesting paper by Prof. Wyman, in ■ Proc- Boston Soc. of Nat. Hist.’ Sept. 15, 1857 ; also Prof. Turner, in ‘ Journal of Anat. and Phys.’ Nov. 1, 1806, p. 78. Dr. Gunther has likewise described similar cases. Chap. VI. AFFINITIES AND GENEALOGY. 211 been known occasionally in man and other mammals to become well developed, and to yield a fair supply of JlJdk. Now if we suppose that during a former pro- longed period male mammals aided the females in nursing their offspring, and that afterwards from some Cause, as from a smaller number of young being pro- duced, the males ceased giving this aid, disuse of the organs during maturity would lead to their becoming tractive; and from two well-known principles of in- heritance this state of inactivity would probably be transmitted to the males at the corresponding age of Maturity. But at all earlier ages these organs would he left unaffected, so that they would be equally well developed in the young of both sexes. Conclusion. — The best definition of advancement or pr°gress in the organic scale ever given, is that by ' °u Baer; and this rests on the amount of differ- entiation and specialisation of the several parts of same being, when arrived, as I should bo inclined 0 add, at maturity. Now as organisms have become alowly adapted by means of natural selection for diversified lines of life, their parts will have become, from the advantage gained by the division of physio- iogical labour, more and more differentiated and spe- cialised for various functions. The same part appears °ften to have been modified first for one purpose, and t]len long afterwards for some other and quite distinct Purpose ; and thus all the parts are rendered more and ^ore complex. But each organism will still retain the general type of structure of the progenitor from which ll:' was aboriginally derived. In accordance with this 'lew it seems, if we turn to geological evidence, that Olganisation on the whole has advanced throughout the " 01ld by slow and interrupted steps. In the great 212 THE DESCENT OP MAN. Part I. kingdom of the Vertebrata it has culminated in man. It must not, however, he supposed that groups of organic beings are always supplanted and disappear as soon as they have given birth to other and more perfect groups. The latter, though victorious over their predecessors, 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 per- fect 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,21 resembling the larvae of existing Ascidians. These animals probably gave rise to a group of fishes, as lowly organised as the lancelet ; and from these the Ganoids, and other fishes like the Lepidosiren, must have been developed. From such fish a very small advance would 27 All vital functions tend to run tlieir course in fixed and recurrent periods, and with tidal animals the periods would probably be lunar ; for such animals must have been left dry or covered deep with water,— ■ supplied with copious food or stinted,— during endless generations, at regular lunar intervals. If then the Vertebrata arc descended from »» animal allied to the existing tidal Ascidians, the mysterious fact, that with tile higher and now terrestrial Vertebrata, not to mention other classes, many normal and abnormal vital prooeBseH run tlieir course according to lunar periods, is rendered intelligible. A recurrent period, if approximately of the right duration, when once gained, would not, os far as we can judge, be liable to he changed ; consequently it might be thus transmitted during almost any number of generations. This conclusion, if it could be proved sound, would be curious ; for we should then see that the period of gestation in each mammal, and the hatching of each bird’s eggs, and many other vital processes, still betrayed the primordial birthplace of these animals. Chap. vi. AFFINITIES AND GENEALOGY. 213 carry us on to the amphibians. We have seen that blrds and reptiles were once intimately connected togetlier ; and the Monotremata now, in a slight degree, c°nnect mammals with reptiles. But no one can at Present say by what line of descent the three higher and related classes, namely, mammals, birds, and rep- t'lcg, were derived from either of the two lower verte- orate classes, namely amphibians and fishes. In the c'lass of mammals the steps are not difficult to con- oeive which led from the ancient Monotremata to ^e ancient Marsupials; and from these to the early progenitors of the placental mammals. We may thus ^oend to the Lemuridee ; and the interval is not wide 10111 these to the Simiadae. The Simiadse then branched into two great stems, the New World and Old World ^°nkeys ; and from the latter, at a remote period, Man, 10 wonder and glory of the Universe, proceeded, j J-hus we have given to man a pedigree of prodigious eilgth, but not, it may be said, of noble quality. The |'°rld, it has often been remarked, appears as if it had °ng been preparing for the advent of man ; and this, in ?rie sense is strictly true, for he owes his birth to a long Jlle of progenitors. If any single link in this chain ad never existed, man would not have been exactly hat he now is. Unless we wilfully close our eyes, we ltlay, with our present knowledge, approximately re- °°guise our parentage ; nor need we feel ashamed of it. Je most humble organism is something much higher aa the inorganic dust under our feet ; and no one ^th an unbiassed mind can study any living creature, °Wever humble, without being struck with enthusiasm lts Marvellous structure and properties. 214 THE DESCENT OF MAN. Part I. CHAPTEE 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 — Mono- genista and polygenisfs — 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 ex- tinction of races — The formation of races — Tlio effects of cross- ing — Slight influence of the direct action of the conditions of life — Slight or no influence of natural selection — Sexual selection. It is not my intention here to describe the several so-called races of men; but to inquire wliat is the value of the differences between them under a classi- ficatory point of view, and how they have originated. In determining whether two or more allied forms ought to he ranked as species or varieties, natu- ralists are practically guided by the following con- siderations ; 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 ; hut 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 ot sterility between any two forms when first crossed, or in their offspring, is generally considered as a decisive Chap, VII. THE RACES OP MAN. 215 test of their specific distinctness ; and their continued Persistence without blending within the same area, is Usually accepted as sufficient evidence, either of some degree of mutual sterility, or in the case of animals of s°me repugnance to mutual pairing. Independently of blending 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 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 |s often unconsciously and sometimes consciously brought into play ; so that forms living in two widely separated areas, iu which most of the other inhabitants are speci- fically distinct, are themsel ves usually looked at as dis- f uict ; but in truth this affords no aid iu distinguishing geographical races from so-called good or true species. Now let us apply these generally-admitted principles the races of man, viewing him in the same spirit as a naturalist would, any other animal. Iu regard to the a> count of difference between the races, we must make 8°nie allowance for our nice powers of discrimination gained by the long habit of observing ourselves. In India, as Elphinstone remarks,1 although a newly-arrived N'lropean cannot at first distinguish the various native laces, yet they soon appear to him extremely dissimilar ; ail(i the Hindoo cannot at first perceive any difference ''tween the several European nations. Even the most distinct races of man, with the exception of certain llegro tribes, are much more like each other in form , 1 1 History of India,’ 1841, vol. i. p. 323. Father Ripa makes exactly 16 same remark with respect to the Chinese. 216 THE DESCENT OF MAN. Taut l than would at first be supposed. Tin’s is well shewn by the French photographs in the Collection Anthropolo- gique du Museum of the men belonging to various races, the greater number of which, as many persons to whom I have shown them have remarked, might pass for Europeans. Nevertheless, 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 differ- ences 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,2 the capa- city of the lungs, the form and capacity of the skull, and even in the convolutions of the brain.3 But it would be an endless task to specify the numerous points of structural difference. The races differ also in con- stitution, 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 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 Malays and the Papuans,4 who live 2 Avast number of measurements of Whites, Blacks, and Indians, are given in the ‘ Investigations in the Military and Antkiopolog. Statistics of American Soldiers,’ by B. A. Gould, I8G9, p. 298-358; on the capacity of the lungs, p. 471. Sec also the numerous ami valuable tables, by Dr. Weisbach, from the observations of Dr. Sclierzer and Dr. Schwarz, in the ' Reise der Novara : Autliropolog. Tlieil,’ 18G7. 3 Sec, for instance, Mr. Marshall’s account of the bruin of a Bush- woman, in ‘Phil, Transact.’ J8G4, p. 519. 1 Wallace, 1 The Malay Archipelago,’ vol. ii, 18G9, p. 17S. Chap. VII. THE RACES OF MAN. 217 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 those on the other side. If a naturalist, who had never before seen such beings, were to compare a Negro, Hottentot, Australian, or Mongolian, ho would at once perceive that they differed in a multi- tude of characters, some of slight and some of consider- able importance. On inquiry he would find that they Were adapted to live under widely different climates, and that they differed somewhat in bodily constitution and niental disposition. 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 Rood species as many to which he had been in the babit 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.5 He would also hear from an excellent observer, 5 With respect to the figures in the famous Egyptian caves of Ahou- Simbel, M. Pouehet says (* The Plurality of the Human Races,’ Eng. U'anslat. 1SG1, p. 50), that he was far from finding recognisable repre- sentations of the dozen or more nations which some authors believe that they can recognise. Even some of the most strongly-marked Woes cannot bo identified with that degree of unanimity which might have been expected from what lias been written on the subject. Thus Messrs. Nott and Gliddou (‘Types of Mankind,' p. 148) state that Raineses II., or the Great, has features superbly European; where- a* Knox, another firm believer in the specific distinction of the races of man (‘Races of Man,’ 1850, p. 201), speaking of young Mcmnon (the same person with Humeses 11., as 1 am iniurmed_by Mr. Birch) in- sists in tlio strongest manner that ho is identical in character with the ■frws of Antwerp? Again, whilst looking in the British Museum with two competent judges, officers of the establishment, at the statue of Kinunoph HI., we agreed that ho had a strongly negro cast of features ; 218 THE DESCENT OF MAN. Part I. Dr. Lund,6 that the human skulls found in the caves of Brazil, entombed with many extinct mammals, belonged to the same type as that now prevailing throughout the American Continent. Our naturalist would then perhaps turn to geogra- phical distribution, and he would probably declare that forms differing not only in appearance, but fitted for the hottest and dampest or driest countries, as well as for the arctic regions, must be distinct species. He might appeal to the fact that no one species in the group next to man, namely the Quadrumana, can resist a low temperature or any considerable change of climate ; and that those species which come nearest to man have never been reared to maturity, even under the temperate climate ot Europe. He would be deeply impressed with the fact, first noticed by Agassiz,7 that the different races of man are distributed over the world in the same zoological provinces, as those inhabited by undoubtedly distinct species and geneva of mammals. This is mani- festly the case with the Australian, Mongolian, and Aegio races ot man ; in a less well-marked manner with the Hottentots ; but plainly with the Papuans aud 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; anefthis 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 but Messrs. Nott and Gliddon (ibid. p. 146, fig. 53) describe him as u a hybrid, but not of negro intermixture” As quoted by Nott and Gliddon, ‘ T}rpes of Mankind/ 1854, p. 439. They give also corroborative evidence ; but C. Vogt thinks that the subject requires further investigation. 1 U Diversity of Origin of the Human Races,” in the ‘ Christian Examiner,’ July, 1850. Chap. vil. THE RACES OF MAN. 219 opossum, range from the one into the other, as did formerly some of the gigantic Edentata. The Esqui- maux, like other Arctic animals, extend round the whole polar regions. It should he observed that the mammalian forms which inhabit the several zoological provinces, do not differ from each other in the same degree; so that it can hardly be considered as an miomaly that the Negro differs more, and the American much less, from the other races oi man than do the mammals of the same continents from those 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 varieties ot the same hind of domestic animal should be ranked as specifically distinct, that is, whether any of them are descended from distinct wild species, every naturalist would lay much stress on the fact, if established, of their external parasites being specifically distinct. All the more stress would be iaid on this fact, as it would be an exceptional one, for i am informed by Mr. Denny that the most different hinds of dogs, fowls, and pigeons, in England, are infested hy the same species of Pediculi or lice. Now Mr. A. Murray has carefully examined the Pediculi collected in different countries from the different races oi man ; 8 ai,d he finds that they differ, not only in colour, but M the structure of their claws and limbs. In every case in which numerous specimens were obtained the differences were constant. The surgeon ol a whaling 8hip in the Pacific assured me that when the Pediculi, with which some Sandwich Islanders on board swarmed, strayed on to the bodies of the English sailors, they died in the course of three or four days. These Pediculi 8 ‘Transact. It. Soc. of Edinburgh,’ vol. xxii. 1861, p. 567. 220 the descent of man. Pakt 1. were darker coloured and appeared different from those proper to the natives of Chiloe in South America, of winch he gave me specimens. These, again, appeared larger and much softer than European lice. Mr. Murray- procured four kinds from Africa, namely from the egioes of the Eastern and Western coasts, from the Hottentots and Caffres; two kinds from the natives of Australia; two from North, and two from South America.^ In these latter cases it may be presumed tnat the Pediculi came from natives inhabiting different districts. With insects slight structural differences, if constant, are generally esteemed of specific value : and tlie 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 m his investigation, would next inquire whether the races of men, when crossed, were in any degree sterile. e might consult the work 9 of a cautious and philo- sophical observer. Professor Broca ; and in this he would ni 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. he 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.10 Again, it has often translat* 18H PhenomoDa of Hybridity in the Genus Homo,’ Eng. 10 See the interesting letter by Mr. T. A. Murray, in the ‘ Antliro- polog. Review, April, 1808, p. liii. Iu this letter Count Strzelecki’s UlIAP. VII. THE RACES OF MAN. 221 been said that when mulattoes intermarry they produce few children; on the other hand, Dr. Bachman of Charlestown 11 positively asserts that he has known Mulatto families which have intermarried for several generations, and have continued on an average as fertile as either pure whites or pure blacks. Inquiries formerly 'nade by Sir C. Lyell on this subject led him, as he informs me, to tire same conclusion. In the United States the census for the year 1 S54 included, according t° Dr. Bachman, 405,751 mulattoes ; and this number, e°Hsidering all the circumstances of the case, seems Stt>all ; but it may partly be accounted for by the de- graded and anomalous position of the class, and by the profligacy of the women. A certain amount of absorp- u°n of mulattoes into negroes must always be in pro- gress ; and this would lead to an apparent diminution °f the former. The inferior vitality of mulattoes is spoken of in a trustworthy work12 as a well-known Phenomenon ; but this is a different consideration from heir lessened fertility ; and can hardly be advanced as a proof of the specific distinctness of the parent races. doubt both animal and vegetable hybrids, when produced from extremely distinct species, are liable to Premature death ; but the parents of mulattoes cannot ( 3 put under the category of extremely distinct species. Die common Mule, so notorious for long life and vigour, and yet, r0 sterile, shews how little necessary connection ’* 0nient, that Australian women who have borne children to a white are afterwards sterile with their own race, is disproved. M. A. de J'tuatrefageg has also collected (‘ Revue des Cours Scientifiques,’ March, “■ P- 23!)) much evidence that Australians and Europeans are not eiile when crossed. of ' An Examination of Prof. Agassiz’s Sketch of the Nat. Provinces 12, Animai World,’ Charleston, 1855, p. 44. n . * Military and Anthropolog. Statistics of American Soldiers.’ bv A. Gould, 18G9, p. 3J9. 222 THE DESCENT OE MAN. Part I- there is in hybrids between lessened fertility and vitality: other analogous eases could be added. 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 reciprocal 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 quite fertile. The degrees of sterility do not coincide strictly with the degrees of difference 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 he advanced in favour of the Pallasian doctrine 13 that domestication tends to eliminate the 13 1 The Varintion of Animals and Plants under Domestication,’ vol. u- p. 109. I may here remind the reader that the sterility of species when crossed is not a specially-acquired quality; but, like the inca- pacity ot certain trees to he grafted together, is incidental on other acquired differences. The nature of these differences is unknown, but they relate more especially to the reproductive system, and much le?13 to external structure or to ordinary differences in constitution. One important element in the sterility of crossed species apparently lies iu one or both having been long habituated to fixed conditions; for w*' know that changed conditions have a special influence on the repro- ductive system, and wo have good reason to believe (us before re- marked) that the fluctuating conditions of domestication tend to elimi- nate that sterility which is so general with species in a natural stale when crossed. It lias elsewhere been shewn by mo (ibid. vol. ii. p- and ‘ Origin of Species,’ 5th edit. p. 317) that the sterility of crossed species has not been acquired through natural selection : we can see that when two forms have already been rendered very sterile, it is scarcely Chap. yij. THE RACES OP MAN. 223 sterility which is so general a result of the crossing of species in a state of nature. From these several con- siderations, it may be justly urged that the perfect ferti- lity of the intercrossed races of man, if established, Vv'°uld not absolutely preclude us from ranking them as distinct species. Independently of fertility, the character of the off- spring from a cross has sometimes been thought to anord evidence whether the parent-forms ought to be j'anked as species or varieties ; but after carefully study- the evidence, I have come to the conclusion that no Seneral rules of this kind can be trusted. Thus with mankind the offspring of distinct races resemble in all r®8pects the offsj wing of true species and of varieties, ^ds is shewn, for instance, by the manner in which characters of both parents are blended, and by one form absorbing another through repeated crosses. 11 this latter case the progeny both of crossed species and varieties retain for a long period a tendency to yevert to their ancestors, especially to that one which ls prepotent in transmission. When any character has Suddenly appeared in a race or species as the result of a t)°ssi'ble that their sterility should be augmented by the preservation or ?Urvival of the more and more slerile individuals; for as the sterility greases fewer and fewer offspring will be produced from which to . reed,and at last only single individuals will be produced, at tire rarest Q..ei vitls. But there is even a higher grade of sterility than this. Both ^ ar frier and Ivdlreuter have proved that in genera of plants including ^ Onerous species, a series can be formed from species which when s|°S3ed ybdd fewer and fewer seeds, to species which never produce a t ,n=le seed, but yot are affected by the pollen of the other species, for G german swells, It is here manifestly impossible to select the more ti^r*k individuals, which have already ceased to yield seeds; so that „ ? acme of sterility, when the ganiicn alone is affected, cannot be Mined through selection. This acme, and no doubt the other grades in are the incidental results of certain unknown differences c Jle constitution of the reproductive system of the species which are 224 THE DESCENT OF MAN. Pabt t single act of variation, as is general with monstrosities,14 and this race is crossed with another not thus charac- terised, the characters in question do not commonly appear in a blended condition in the young, but are transmitted to them either perfectly developed or not at all. As with the crossed races of man cases of this kind rarely or never occur, this may be used as an argument against the view suggested by some ethnologists, namely that certain characters, for instance the blackness of the negro, first appeared as a sudden variation or sport. Had this occurred, it is probable that mulattoes would often have been born, either completely black or com- pletely white. We have now seen that a naturalist might feel him- self 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, re- mained nearly constant for very long periods of time. He 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 with the distribution of the several so-called races, in accordance 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 kept distinct like ordinary species, when mingled to- 14 ‘ The Variation of Animals,’ &c., vol. ii. p. 92. Chap. VII. THE EACES OF MAN. 225 pettier in large numbers in the same country, be would ^mediately discover that this was by no means the Case, In Brazil he would behold an immense mongrel population of Negroes and Portuguese ; in Chiloe and other parts of South America, lie would behold the "'hole population consisting of Indians and Spaniards tended in various degrees.13 In many parts of the same continent he would meet with the most complex erosses between Negroes, Indians, and Europeans ; and such triple crosses afford the severest test, judging from the vegetable kingdom, of the mutual fertility of the Parent-forms. In one island of the Pacific he would hud a small population of mingled Polynesian and ■^uglish blood ; and in the Viti Archipelago a popula- tion of Polynesians and Negritos crossed in all degrees, ^lany analogous cases could he added, for instance, in ®°uth Africa. Hence the races of man are not sufifi- Oently distinct to co-exist without fusion ; and this it Js> which in all ordinary cases affords the usual test of specific distinctness. Phir naturalist would likewise be much disturbed as s°°n as he perceived that tbe distinctive characters of eVery race of man were highly variable. This strikes every one when be first beholds the negro-slaves in Brazil, who have been imported from all parts of Africa. Bhe same remark holds good with the Polynesians, and "ith many other races. It may he doubted whether auy character can be named which is distinctive of a 1,lCe and is constant. Savages, even within the limits of le same tribe, are not nearly so uniform in character, as has often been said. Hottentot women offer certain de Quutrefages lias given (‘ Anthropolog. Review,’ Jan. I860, P an interesting account of the success and energy of the Paulistas a 1 who are a much crossed race of Portuguese and Indians, with auxture of the blood of other races. VOL. I. Q 226 THE DESCENT OE MAN. Part I- peculiarities, more strongly marked than those occur- ring in any other race, but these are known not to he of constant occurrence. In the several American tribes, colour and hairyness 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 ; 16 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 characters. But the most weighty of all the arguments against treating the races of man as distinct species, 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 organic being, 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 (Yirey), as three (.Jacquinot), as four (Kant), five (Blumenbach), six (Buffon), seven (Hunter), eight (Agassiz), eleven (Pickering), fifteen (Bory St, Yiucent), sixteen (Des- moulins), twenty-two (Morton), sixty (Crawfurd), or as sixty-three, according to Burke.17 This diversity of judgment does not prove that the races ought not to be ranked as species, but it shews that they graduate into each other, and that it is hardly possible to discover clear distinctive characters between them. Every naturalist who has had the misfortune to under- 16 For instance with the aborigines of America and Australia. Prof- Huxley says (‘ Transact. Internat. Congress of Prehist. Arch.’ 1808, P- 105) that the skulls of many South Germans and Swiss are “as short “ and as broad as those of the Tartars,” &c. 17 Soe a good discussion on this subject in Waitz, 1 Introduct. to Anthropology,’ Eng. translat. 1863, p. "l98-208, 227. I have taken some of the above statements from Id. Tuttle’s ‘Origin and Antiquity of Physical Man,’ Boston, 1866, p. 35. chap. yil. THE RACES OF MAH. 227 take the description of a group of highly varying organisms, has encountered cases (I speak after ex- perience) precisely like that of man ; and if of a cautious disposition, ho will end by uniting all the forms which graduate into each other as 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 111 the Order which includes man, namely in certain genera of monkeys ; whilst in other genera, as in Cerco- Pithecus, 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 Specimens of Cebus were collected from all parts of fo°uth America, and those forms which at present ap- Pear to be specifically distinct, were found to graduate mto each other by close steps, they would be ranked by ^ost naturalists as mere varieties or races ; and thus the greater number of naturalists have acted with respect to the races of man. Nevertheless it must be confessed ^at there are forms, at least in the vegetable king- dom,18 which we cannot avoid naming as species, but which are connected together, independently of inter- crossing, by numberless gradations. Some naturalists have lately employed the term ‘sub-species” to designate forms which possess many of the characteristics of true species, but which hardly de- Serve so high a rank. Now if we reflect on the weighty arguinents, above given, for raising the races of man to t!'e dignity of species, and the insuperable difficulties 0,1 the other side in defining them, the term “ sub- i p Prof. Jiageli lias carefully described several striking cases in his utailisclic Mittheilungen,’ B. ii. 1SGG, s. 294-369. Prof. Asa Gray w made analogous remarks on some intermediate forms in the Com- P'mtaeofK. America. Q 2 228 THE DESCENT OF MAN. Paf.t I. species ” might here be used with much propriety. But from long habit the term “race” will perhaps always be employed. The choice of terms is only so far im- portant as it is highly desirable to use, as far as that may be possible, the same terms for the same degrees of difference. Unfortunately this is rarely possible; for within the same family the larger genera generally include closely-allied forms, which can be distinguished only with much difficulty, whilst the smaller genera include forms that are perfectly distinct ; yet all must equally be ranked as species. So again the species within the same large genus by no means resemble each other to the same degree : on the contrary, in most cases some of them can be arranged in little groups round other species, like satellites round planets.19 The question whether mankind consists of one or seveial species has of late years been much agitated by anthropologists, who are divided into two schools of monog'enists and polygenists. Those who do not admit the principle of evolution, must look at species either as separate creations or as in some manner distinct entitles ; and they must decide what forms to rank as species by the analogy of other organic beings which are commonly thus received. But it is a hopeless en- deavour to decide this point on sound grounds, until some definition of the term “ species ” is generally ac- cepted ; and the definition must not include an element which cannot possibly be ascertained, such as an act of creation. We might as well attempt without any defi- nition to decide whether a certain number of houses should be called a village, or town, or city. We have a practical illustration of the difficulty in the never- ‘ Origin of Species,’ 5th edit. p. G8. C'HAP. vil. THE RACES OP MAH. 229 ending doubts whether many closely-allied mammals, ^irds, insects, and plants, which represent each other in ■^orth America and Europe, should be ranked species °r geographical races ; and so it is with the productions °f 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 greater number of rising men, will feel no doubt that all the races of man are descended from a single primi- tive stock; whether or not they think fit to designate them as distinct species, for the sake of expressing their amoimt of difference.20 With our domestic animals the question whether the various races have arisen from °ne or more species is different. Although all such races, as well as all the natural species within the same genus, have undoubtedly sprung from the same primi- tive stock, yet it is a fit subject for discussion, whether, 0r instance, all the domestic races of the dog have Squired their present differences since some one species "’as first domesticated and bred by man ; or whether they °w° some of their characters to inheritance from distinct species, which had already been modified in a state of Mature. With mankind no such question can arise, for cannot be said to have been domesticated at any Particular period. When the races of man diverged at an extremely inuiote epoch from their common progenitor, they will have differed but little from each other, and been few ’u number; consequently they will then, as far as their distinguishing characters are concerned, have had' less claim to rank as distinct species, than the existing so- ° ®ee Prof. Huxley to this effect in the ‘ Fortnightly Eeview,’ 1865 P- 275. * 230 THE DESCENT OF MAN. Part I- called races. Nevertheless such early races would per- haps have been ranked by some naturalists as distinct species, so arbitrary is the term, if their differences, although extremely slight, had been more constant than at present, and had not graduated into each other. It is, however, possible, though far from probable, that the early progenitors of man might at first have diverged much in character, until they became more unlike each other than are any existing races ; but that subsequently, as suggested by Vogt,21 they converged in character. When man selects for the same object the offspring of two distinct species, he sometimes induces, as far as general appearance is concerned, a considerable amount of convergence. This is the case, as shewn by Von Nathusius," with the improved breeds of pigs, which are descended from two distinct species ; and in a less well-marked manner with the improved breeds of cattle. A great anatomist, Gratiolet, maintains that the anthropomorphous apes do not form a natural sub-group ; hut 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, we 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 resemblances. I* 51 ‘ Lectures on Mau,’ Eng, translat. 1864, p. 468. 2-’ ‘Die Itacon des Schweines,’ I860, s. 46. ‘Vorstudien fur Ge- schichte, &c„ Schweineschadcl,’ 1864, s. 104. With respect to cattle, see M. de Quatrefages, ‘ Unite' de l’Espcoe liumaine,’ 1861, p. 119. CiUp. VII. THE RACES OF MAN. 231 '?ould be extremely rash in most cases to attribute to convergence close similarity in many points of struc- lore in beings which had once been widely different. form of a crystal is determined solely by the Molecular forces, and it is not surprising that dissimilar ^stances should sometimes assume the same form ; c^t with organic beings we should bear in mind that ^le form of each depends on an infinitude of complex Nations, namely on the variations which have arisen, these being due to causes far too intricate to be followed °Ut, — on the nature of the variations which have been Preserved, and this depends on the surrounding physical c'°nditions, and in a still higher degree on the sur- r°unding organisms with which each has come into '''’’“petition, — and lastly, on inheritance (in itself a Uctuating element) from innumerable progenitors, all 0 which have had their forms determined through ^finally complex relations. It appears utterly incredible ,lat two organisms, if differing in a marked manner, hould ever afterwards converge so closely as to lead 0 a near approach to identity throughout their whole °j‘ganisation. In the case of the convergent races of pigs )°ve referred to, evidence of their descent from two pri- ?Aive stocks is still plainly retained, according to Yon utliusius, in certain bones of their skulls. If the races ’nan were descended, as supposed by some naturalists, °ta two or more distinct species, which had differed as ^tach, or nearly as much, from each other, as the orang ’Hers from the gorilla, it can hardly be doubted that Marked differences in the structure of certain bones would 8tlH have been discoverable in man as he now exists. Although the existing races of man differ in many ^spects, as in colour, hair, shape of skull, proportions the body, &c., yet if their whole organisation be taken 232 THE DESCENT OF MAN. Pakt i. into consideration they are found to resemble each other closely in a multitude of points. Many of these points are oi so unimportant or of so singular a nature, that it is extremely improbable that they should have been independently 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 ol man. The American aborigines, Negroes and Europeans differ as much from each other in mind as any three races that can be named ; yet I was incessantly struck, whilst living with the Fuegians on hoard 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 he intimate. He who will carefully read Mr. Tylor’s and Sir J. Lubbock’s interesting works 23 can hardly fail to be deeply impressed with the close similarity between tlm men ot 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 — and, as I shall be able to shew in a future essay, by the same expression in their features, and by the same inarticulate cries, when they are excited by various emotions. This similarity, or rather identity, is striking, when contrasted with the different expressions which may be observed in distinct species of monkeys. There is good evi- dence that the art of shooting with bows and arrows has not been handed down from any common progenitor of Tylor s ‘ Early History of Mankind,’ 1865 ; for the evidence rvith respect to gesture-language, see p. 54. Lubbock’s 1 Prehistoric Times,’ 2nd edit. 1869. Chap. VII. THE RACES OF MAX. 233 Mankind, yet the stone arrow-heads, brought from the niost distant parts of the world and manufactured at the most remote periods, are, as Nilsson has shewn,24 almost Mention] ; and this fact can only be accounted for by various races having similar inventive or mental powers. The same observation lias been made by archseologists 25 with respect to certain widoly-prevalent ornaments, such as zigzags, &c.; and with respect to "arious simple beliefs and customs, such as the burying of the dead under megalithic structures. I remember observing in South America,26 that there, as in so many other parts of the world, man has generally chosen the summits of lofty hills, on which to throw up piles of stones, either for the sake of recording some remarkable eVent, or tor burying his 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- mlied natural forms, they use this fact as an argument that all are descended from a common progenitor who "'as thus endowed ; and consequently (hat all should be Massed under the same species. The same argument umy be applied with much force to the races of man. As it is improbable that the numerous and unim- portant points of resemblance between the several races °f man in bodily structure and mental faculties (I do uot here refer to similar customs) should all have been independently acquired, they must have been inherited from, progenitors who were thus characterised. We thus gain some insight into the early state of man, 24 ‘ The Primitive Inhabitants of Scandinavia,’ Eng. translat. edited -~Ar J- Lubbock, 18(18, p. 101. Hodder M. Westropp, on Cromlechs, &c., ‘Journal of Ethno- °gical Soc.’ as given in ‘Scientific Opinion,’ June 2nd, I860, p. 3. *6 ‘Journal of Researches : Voyage of the “ Beigle,” ’ p. 46. 234 THE DESCENT OF MAN. Part I- before he had spread step by step over the face of the eaith. The spreading ot man to regions widely sepa- rated by the sea, no doubt, preceded any considerable amount of divergence of character in the several races; tor otherwise we should sometimes meet with the same lace 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, specifies those which man could not have known, when he first wan- dered from his original birth-place; for if once learnt they would never have been forgotten. K He thus 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 fire probably had already been dis- covered, for it is common to all the races now existing, and was known to the ancient cave-inhabitants of Lurope. Perhaps the art of making rude canoes or rafts was likewise known; but as man existed at a re- mote epoch, when the land in many places stood at a very different level, 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, consider- ing that so many races now' in existence cannot get “ beyond four.” Nevertheless, at this early period, the intellectual and social faculties of man could* hardly have been inferior in any extreme degree to those now pos- sessed 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. iiom the fundamental differences between certain 3r ‘ Prehistoric Times,’ 1809, p. 574. THE EACES OF MAN. 235 Ca. AP. VII. languages, some philologists have inferred that when ^an first became widely diffused he was not a speaking animal; but it may he suspected that languages, far less perfect than any now spoken, aided by gestures, 'night have been used, and yet have left no traces °n subsequent and more highly-developed tongues. W ithout the use of some language, however imperfect, If appears doubtful whether man s intellect could have r'sen to the standard implied by his dominant position at an early period. Whether primeval man, when he possessed very few arts 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 which we employ. In a series of forms graduating insensibly l'r°m some ape-like creature to man as he now exists, h would be impossible to fix on any definite point when term “ man ” ought to be used. But this is a matter very little importance. So again it is almost a Matter of indifference whether the so-called races of 'nan are thus designated, or are ranked as species 0t sub-species ; but the latter term appears the most appropriate. Finally, we may conclude that when Ike principles of evolution are generally accepted, as tlley surely will be before long, the dispute between the Cconogenists and the polygeuists will die a silent and Unobserved death. Bne other question ought not to be passed over "dthout notice, namely, whether, as is sometimes assumed, each sub-species or race of man has sprung l0m a single pair of progenitors. With our domestic anjmals a new race can readily be formed from a single pair possessing some new character, or even from a 8lngle individual thus characterised, by carefully match- 236 THE DESCENT OF MAN. Part !• ing the varying offspring ; bnt most of our races have been formed, not intentionally from a selected paib but unconsciously by the preservation of many indi- viduals 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 horses, were habitually preferred, we may feel sure that two distinct sub-breeds would, in the course of time, be produced, without any particular pairs or individuals having been separated and bred from in either country. Many races have been thus formed; and their manner of formation is closely analogous with that of natural species. We know, also, that the horses which have been brought to the Falkland Islands have become, during successive generations) 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 m none of these cases are 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 Races of Man. — The partial and complete extinction of many races and sub-races of man are historically known events. Humboldt saw in South America a parrot which was the sole living creature that could speak the language of a lost tribe. ^hap. vn. THE RACES OF MAN. 237 An ''ient monuments and stone implements found in aH parts of the world, of which no tradition is pre- Served by the present inhabitants, indicate much extinction. Some small and broken tribes, remnants °f former races, still survive in isolated and gene- ra% mountainous districts. In Europe the ancient races were all, according to Schaaffhausen,28 “ 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 •Broca29 from Les Eyzies, though they unfortunately appear to have belonged to a single family, indicate a ra°e with a most singular combination of low or simious and high characteristics, and is “entirely different 1 horn any other race, ancient or modern, that we have “ ever heard of.” It differed, therefore, from the qua- ternary race of the caverns of Belgium. Unfavourable physical conditions appear to have had little effect in the extinction of races.30 Man has ^°ug lived in the- extreme regions of the North, with 110 wood wherewith to make his canoes or other imple- ments, and with blubber alone for burning and giving din warmth, but more especially for melting the snow. 11 the Southern extremity of America the Euegians without the protection of clothes, or of any Building worthy to he called a hovel. In South Africa ^Be aborigines wander over the most arid plains, where dangerous beasts abound. Man can withstand the deadly influence of the Terai at the toot ot the Hima- aya, and the pestilential shores of tropical Africa. f Translation in ‘Anthropological Review, Oet. 1868, p. 431. _ J ‘Transact. Internat. Congress of Prehistoric Arch. 1868, p. 172- ,'5- See also Broca (translation) in ‘Anthropological Review,’ Oct. P. 410. * T»r. Gerland ‘ TJeher das Autsterben dor Naturvolker,1 1868, s. 82. 238 THE DESCENT OF MAN. Pakt I- Extinction follows chiefly from the competition of tribe with tribe, and race with race. Various checks are always in action, as specified in a former chapter, which serve to keep down the numbers of each savage tribe, — such as periodical famines, the wandering of the parents and the consequent deaths of infants, pro- longed suckling, the stealing of women, wars, accidents, sickness, licentiousness, especially infanticide, and, perhaps, lessened fertility from less nutritious food, and many hardships. If from any cause any one of these checks is lessened, even in a slight degree, the tribe thus favoured will tend to increase; and when one of two adjoining tribes becomes more numerous and 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 is extinct.31 When civilised nations come into contact with bar- barians the struggle is short, except where a deadly cli- mate gives its aid to the native race. Of the causes which lead to the victory of civilised nations, some are plain and some very 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. Xe'V diseases and vices are highly destructive ; and it appears that in every nation a new disease causes much death, until those who are most susceptible to its destructive influence are gradually weeded out;52 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 savages. It further appears, mysterious as is ” Gerland (ibid. s. 12) gives facts in support of this statement. See remarks to this effect in Sir H. Holland’s ‘ Medical Notes and Reflections, ’ 1839, p. 390. c«ap. vii. tiib races op man. 239 fact, that the first meeting of distinct and separated People generates disease.33 Mr. Sproat, who in Man- euver Island closely attended to the subject of extinc- tion, believes that changed habits of life, which always follow from the advent of Europeans, induces much ill- health. He lays, also, great stress on so trifling a cause as that the natives become “ bewildered and dull by the “ new life around them ; they lose the motives for exer- tion, and get no new ones in their place.” "i The grade of civilisation seems a most important dement in the success of nations which come in compe- tition. A few centuries ago Europe feared the inroads °f Eastern barbarians ; now, any such fear would be ridi- culous. It is a more curious fact, that savages did not formerly waste away, as Mr. Bagehot has remarked, hefore the classical nations, as they now do before Modern civilised nations; had they done so, the old 'n°i'alists would have mused over the event ; hut there ls Uo lament in any writer of that period over the perish- 111 § barbarians.36 Although the gradual decrease and final extinction °f the races of man is an obscure problem, we can see fhat it depends on many causes, differing in different Pieces and at different times. It is the same difficult Problem as that presented by the extinction of one of tl|e higher animals— of the fossil horse, for instance, 'vhich disappeared from South America, soon afterwards f° be replaced, within the same districts, by countless tr°ops of the Spanish horse. The New Zealander seems ^ I have Uce toil (‘Journal of Researches, Voyage of the “Beagle,”’ j Jo) a good many oases bearing on this subject : see also Gerland, s. 8. Poeppig speaks of tho “ breath of civilisation as poisonous w savages.” ^ kproat, ‘ Scenes and Studies of Savage Life,’ 1868, p. 284. 1 On ®agehot, <* Physics and Politics,” ‘ Fortnightly Review,’ April 1, lb6s> p. 455. 240 THE DESCENT OF MAN. Part I- conscious of this parallelism, for he compares his future fate with that of the native rat almost exterminated by the European rat. The difficulty, though great to our imagination, and really great if we wish to ascertain the precise causes, ought not to be so to our reason, as long as we keep steadily in mind that the increase of each species and each race is constantly hindered by various checks ; so that if any new check, or cause of destruction, even a slight one, be superadded, the race will surely decrease iu number ; and as it has ever}" where been observed that savages are much opposed to any change of habits, by which means injurious checks could he counterbalanced, decreasing numbers will sooner or later lead to extinction ; the- end, in most cases, being promptly determined by the inroads of increasing and conquering tribes. On the Formation of the Races of Man.— It may be premised that when we find the same race, though broken up into distinct tribes, ranging over a great area, as over America, we may attribute their general resemblance to descent from a common stock. In some cases the crossing of races already distinct has led to the formation of new races. The singular fact that Europeans and Hindoos, who belong to the same Aryan stock and speak a language fundamentally the same, differ widely in appearance, whilst Europeans differ but little from Jews, who belong to the Semitic stock and speak quite another language, has been accounted for by Broca® through the Aryan branches having been largely crossed during their wide diffusion by various indigenous tribes. When two races in close contact 3f. .. Or Anthropology,” translation, * Anthropolog. Review,’ Ja"' 186S, p, 38. CHAP; VII. the races of man. 241 Cr°ss, the first result is a heterogeneous mixture : thus Mr. Hunter, in describing the Santali or hill- tribes of India, says that hundreds of imperceptible gradations may be traced “ from the black, squat tribes “ of the mountains to the tall olive-coloured Brahman, “ 'Hth his intellectual brow, calm eyes, and high but “ Harrow head ; ” so that it is necessary in courts of justice to ask the witnesses whether they are Santalis °r Hindoos.37 Whether a heterogeneous people, such as the inhabitants of some of the Polynesian islands, formed by the crossing of two distinct races, with few 0r no pure members left, would ever become homo- 8eneous, is not known from direct evidence. But as "ith our domesticated animals, a crossed breed can Cei'tainly, in the course of a few generations, be fixed aud made uniform by careful selection,38 we may infer ^at the free and prolonged intercrossing during many generations of a heterogeneous mixture would supply the place of selection, and overcome any tendency to reversion, so that a crossed race would ultimately be- c°nie homogeneous, though it might not partake in an UfiUal degree of the characters of the two parent-races. Of all the differences between the races of man, the c°loiu- of the skin is the most conspicuous and one of the best marked. Differences of this kind, it was for- tVlerly thought, could be accounted for by long expo- 8ure under different climates ; but Pallas first shewed that this view is not tenable, and he has been followed h)' almost all anthropologists.39 The view has been '' ' The Armais of Rural Bengal,’ 1868, p. 134. 1 The Variation of Animals and Wants under Domestication,’ vol. “• P. 95. 39 Tallas, ‘Act. Acad. St. Fetersburgk,’ 1780, part ii. p. 69. He as followed by Rudolphi, in his ‘Beytriige zuv Authropologie,’ 1812. pa ex«ellent summary of the evidence is given by Godron, ‘He. Esptoe,’ 1859, vol. ii. p. 246, &c. VOL. I, R 242 THE DESCENT OF MAN. Part I- rejected chiefly because the distribution of the variously coloured races, most of whom must have long inhabited their present homes, does not coincide with correspond- ing differences of climate. Weight must also be given to such cases as that of the Dutch families, who, ilS we hear on excellent authority,40 have not undergone the least change of colour, after residing for three cen- turies in South Africa. The uniform appearance in various parts of the world of gypsies and Jews, though the uniformity of the latter has been somewhat exag'ge' rated,41 is likewise an argument on the same side. very damp or a very dry atmosphere has been supposed to be more influential in modifying the colour of the skin than mere heat ; but as D'Orbigny in South America, and Livingstone in Afiica, arrived at diame- trically opposite conclusions with respect to dampness and dryness, any conclusion on this head must be com sidered as very doubtful.44 Various facts, which I have elsewhere given, prove that the colour of the skin and hair is sometimes corre- lated in a surprising manner with a complete immunity from the action of certain vegetable poisons and iron1 the attacks of certain parasites. Hence it occurred to me, that negroes and other dark races might have acquired their dark tints by the darker individual5 escaping during a long series of generations iron1 the deadly influence of the miasmas of their native countries. I aiterwards found that the same idea had long aS° 4(1 Sir Andrew Smith, as quoted by Knox, ‘ Paces of Man,’ p.473. 41 See De Quatrefages on this bead, ‘ Revue des Cours Scicnti£ that the greater number of German families settled in Georgia, hav0 acquired in the course of two generations dark hair and eyes. Mr. D- Forbes informs me that the Quichuas in the Andes vary greatly colour, according to the position of the valleys inhabited by them. al Harlan, ‘Medical Researches,’ p. 532. Quatrefages (‘Unite de 1’Espece Humaine,’ 1861, p. 128) has collected much evidence on this head. Chap. vil. THE RACES OF MAN. 247 about the hot forests of the interior and live chiefly on Vegetable productions ; yet these tribes resemble each other so closely that the Fuegians on board the “ Beagle” Were mistaken by some Brazilians for Botocudos. The Lotocudos again, as well as the other inhabitants of tl'°pical America, are wholly different from the Negroes who inhabit the opposite shores of the Atlantic, are exposed to a nearly similar climate, and follow nearly the same habits of life. Nor can the differences between the races of man be ^counted for, excejjt to a quite insignificant degree, by the inherited effects of the increased or decreased use of Parts. Men who habitually live in canoes, may have their legs somewhat stunted ; those who inhabit lofty regionS have their chests enlarged ; and those who con- stantly use certain sense-organs have the cavities in which they are lodged somewhat increased in size, and their features consequently a little modified. With civilised nations, the reduced size of the jaws fiom lessened use, the habitual play of different muscles serving to express different emotions, and the increased size of the brain from greater intellectual activity, have together produced a considerable effect on their general aPpearauce in comparison with savages.52 It is also Possible that increased bodily stature, with no corre- 8poncling increase in the size of the brain, may have given to some races (judging from the previously ad- duced cases of the rabbits) au elongated skull of the dolichocephalic type. Lastly, the little-understood principle of correlation Will almost certainly have come into action, as in the case of great muscular development and strongly pro- 62 See Prof. Sckaaffkausen, translat. in ‘Anthropological Review,’ 0ch 1868. p. 429. '248 THE DESCENT OF MAN. Pakt L jecting supra-orbital ridges. It is not improbable that the texture of the hair, which differs much in the d if" feieut races, may stand in some kind of correlation with the structure of the skin ; for the colour of the hair and skin are certainly correlated, as is its colour and texture with the Mandans. 53 The colour of the skin and the odour emitted by it are likewise in some rnan- nei connected. With the breeds of sheep the number of hairs within a given space and the number of the excretory pores stand in some relation to each other.54 It we may judge from the analogy of our domesticated animals, many modifications of structure in man pro- bably come under this principle of correlated growth. We have now seen that the characteristic differences between the races of man cannot be accounted for in a satisfactory manner by the direct action of the condi- tions of life, nor by the effects of the continued use of parts, nor through the principle of correlation. We are therefore led to inquire whether slight individual differences, to which man is eminently liable, may not have been preserved and augmented during a long series of generations through natural selection. But here we are at once met by the objection that beneficial variations alone can bo thus preserved; and as far as we are enabled to judge (although always liable to error on this head) not one of the external differ- ences between the races of man is of any direct or Mr. Gatlin states (‘ N. American Indians,' 3rd edit. 1842, vof. i. P- 49) that in the whole tribe of the Mandans, about one in ten or twelve of the members of all ages and both sexes have bright silvery grey hair, which is hereditary. Now this hair is as coarse and harsh as that of a horse’s mane, whilst the hair of other colours is fine and soft. “ On the odour of the skin, Godron, ‘Sur PEspece,’ tom. ii. p. 217. ie pores in the skin, Dr. Wilokena, ‘Die Aufgaben der landwirth- Zootecliuik, 1869, s. 7. chap. VII. THE EACES OF MAN. 249 sPecial service to him. The intellectual and moral 01 s«cial faculties must of course be excepted from this re- mark ; hut differences in these faculties can have had little or no influence on external characters, lhe vari- ability of all the characteristic differences between the races, before referred to, likewise indicates that these hifterenccs cannot be of much importance , for, had they been important, they would long ago have been either fixed and preserved, or eliminated. In this Aspect man resembles those forms, called by naturalists Protean or polymorphic, which have remained extiemely variable, owing, as it seems, to their variations being of an indifferent nature, and consequently to their having leaped the action of natural selection. We have thus far been baffled in all our attempts account for the differences between the races of man , hut there remains one important agency, namely Sexual ^election, which appears to have acted as powerfully °U man, as on many other animals. I do not intend to assert that sexual selection will account lor all the differences between the races. An unexplained resi- duum is left, about which we can in our ignorance only say, that as individuals are continually born with, f°r instance, heads a littlo rounder or narrower, and With noses a little longer or shorter, such slight dif- ferences might become fixed and uniform, if the un- known agencies which induced them were to act in a more constant manner, aided by long-continued inter- crossing. Such modifications come under the provi- sional class, alluded to iu our fourth chapter, which for the want of a better term have been called spontaneous variations. Nor do I pretend that the effects ol sexual selection can be indicated with scientific precision ; but it can be shewn that it would be an inexplicable fact if man had not been modified by this agency, which has 250 THE DESCENT OF MAN. Part I. acted so powerfully on innumerable animals, both high and low in the scale. It can further be shewn that the differences between the races of man, as in colour, hairy- ness, form ol features, &c., are of the nature which it might, have been expected would have been acted on by sexual selection. But in order to treat this subject in a fitting manner, I have found it necessary to pass the whole animal kingdom in review ; I have therefore de- voted to it the Second Part of this work. At the close I shall return to man, and, after attempting to shew how far he has been modified through sexual selection, will give a brief summary of the chapters in this First Part. Part II. SEXUAL SELECTION. Part II.— SEXUAL SELECTION. CHAPTER 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 ot the male Variability of the male — Choice exerted by the female — Sexual compared w ith 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 — On the limita- tion of the numbers of the two sexes through natural selection. With animals which have their sexes separated, the ^ales necessarily diffeT from the females in their organs °f reproduction ; and these afford the primary sexual characters. But the sexes often differ in what Hunter has called secondary sexual characters, which are not Erectly connected with the act of reproduction; for ^stance, in the male possessing certain organs of sense 0r locomotion, of which the female is quite destitute, or hi having them more highly-developed, in older that he may readily find or reach her ; or again, in the male having special organs of prehension so as to hold her securely. These latter organs of infinitely diversified hinds graduate into, and in some cases can hardly be distinguished from, those which are commonly ranked as primary, such as the complex appendages at the aPex of the abdomen in male insects. Unless indeed 254 THE PRINCIPLES OF Part II. we confine the term “primary” to the reproductive glands, it is scarcely possible to decide, as far as the oigans of prehension are concerned, which ought to be called primary and which secondary. Ihe female often differs from the male in having organs for the nourishment or protection of her young, as the mammary glands of mammals, and the ab- dominal sacks of the marsupials. The male, also, in some few cases differs from the female in possessing analogous organs, as the receptacles for the ova pos- sessed by the males of certain fishes, and those tem- porarily developed in certain male frogs. Female bees ba\e a special apparatus for collecting and carrying pollen, and their ovipositor is modified into a sting for the defence of their larvae and the community. In the females of many insects the ovipositor is modified in the most complex manner for the safe placing of the eggs. Numerous similar cases could bo given, but they do not here concern us. There are, however, other sexual differences quite disconnected with the primary 01 gaiis with which 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 orna- ments, his power of song, and other such characters. besides the foregoing primary and secondary sexual differences, the male and female sometimes differ in structures connected with different habits of life, and not at all, or only indirectly, related to the reproductive functions. I bus the females of certain flies (Culicid® and Tabitu id;o) are blood-suckers, whilst the males live on flowers and have their mouths destitute of man- dibles.1 The males alone of certain moths and of some 1 Westwood, ‘Modern Class, of Insects,’ vol. ii. 1840, p. 541. 1 11 Ciui>. yin. SEXUAL SELECTION. 255 crustaceans (e.g. Tanais) have imperfect, closed mouths, and cannot feed. The Complemental males of certain ('h'i'ipedes live like epiphytic plants either on the female or hermaphrodite form, and are destitute of a mouth and prehensile limbs. In these cases it is the male ’"'hick has been modified and has lost certain import- ant organs, which the females and other members of the ®anie group possess. In other cases it is the female "’hick has lost such parts; for instance, the female glow- worm is destitute of wings, as are many female moths, some of which never leave their cocoons. Many female Parasitic crustaceans have lost their natatory legs. In s°me weevil-beetles (Cureulionidae) there is a great difference between the male and female in the length the rostrum or snout ; 2 but the meaning of this anti °f many analogous differences, is not at all understood, differences of structure between the two sexes in rela- tion to different habits of life are generally confined to the lower animals ; but with some few birds the beak °t the male differs from that of the female. No doubt ‘a most, but apparently not in all these cases, the dif- ferences are indirectly connected with the propagation °f the species : thus a female which has to nourish a Altitude of ova will require more food than the male, afel consequently will require special means for procur- ing it. A male animal which lived for a very short time might, without detriment lose through disuse its 0l‘gans for procuring food ; hut he would retain his locomotive organs in a perfect state, so that he might reach the female. The female, on the other hand, foight safely lose her organs for flying, swimming, "’Sard to the statement about Tanais, mentioned below, I am indebted t0 Tritz Muller. 2 Kirby and Spence, ‘Introduction to Entomology,’ vol. iii. 1S26, P. 309. 256 THE PRINCIPLES OF Part It or walking, if she gradually acquired habits which ren- dered such powers useless, ^ e are, however, here concerned only with that kind of selection, which I hare called sexual selection. This depends on the advantage which certain individuals have over other individuals of the same sex and species, in exclusive relation to reproduction. When the two sexes differ in structure in relation to different habits of life, as in the cases above mentioned, they have no doubt been modified through natural selection, accompanied, by inheritance limited to one and the same sex. So again the primary sexual organs, and those for nourish- ing or protecting the young, come under this same head ; for those individuals which generated or nourished their offspring best, would leave, extern 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 search for the female, he requires for this purpose oigans 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. VV hen the male has found the female he sometimes absolutely requires prehensile organs to hold her ; thus Dr. Wallace informs me that the males of cer- tain moths cannot unite with the females if their tarsi or feet are broken. Ihe males of many oceanic crusta- ceans have their legs and antennas modified in an extra- ordinary manner for the prehension of the female! Imnce we may suspect that owing to these animals being washed about by the waves of the open sea, they absolutely require these organs in order to propagate theii kind, and it so their development will have bee11 the result of ordinary or natural selection. When the two sexes follow exactly the same habits CHAI>. VIII. SEXUAL SELECT IOX. 257 °f life, and tlie male has more highly developed sense °r locomotive organs than the female, it may be that those in their perfected state are indispensable to the ’Hale for finding the female ; but in tl^e vast majority °f cases, they serve only to give one male an advan- tage over another, for the less well-endowed males, time were allowed them, would succeed in pair- ing with the females; and they would in all other Aspects, judging from the structure of the female, he dually well adapted for their ordinary habits of life. In such cases sexual selection must have come into notion, for the males have acquired their present struc- ture, not from being better fitted to survive in the struggle for existence, but from having gained an ad- jutage over other males, aud from having transmitted this advantage to their male offspring alone. It was the lruportance of this distinction which led me to designate this form of selection as sexual selection. So again, h the chief service rendered to the male by his pre- luensile organs is to prevent the escape of the female before the arrival of other males, or when assaulted by them, these organs will have been perfected through 8eXual selection, that is by the advantage acquired by Cei'tain males over their rivals. But in most cases it ls scarcely possible to distinguish between the effects °f natural and sexual selection. Whole chapters could easdy he filled with details on the differences between the sexes in their sensory, locomotive, and prehensile ?rgans. As, however, these structures are not more mteresting than others adapted for the ordinary pur- poses of life, I shall almost pass them over, giving only a low instances under each class. there are many other structures and instincts which just have been developed through sexual selection — Sllch as the weapons of offence and the means of defence vol. i. s 258 THE PKINCIPLES OP Part XI- possessed by the males for fighting with and driving away their rivals — their courage and pugnacity — their ornaments of many kinds — their organs for producing vocal or instrumental music — and their glands for emitting odours; most of these latter structures serv- ing only to allure or excite the female. That these characters are the result ol sexual and not of ordinary selection is clear, as unarmed, unornamented, or un- attractive males would succeed equally well in the battle for liie and in leaving a numerous progeny, if better endowed males were not present. We may infer that this would be the case, for the females, which are 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 they are in many respects in' teresting, but more especially as they depend on the will, choice, and rivalry of the individuals of either sex. W hen we behold twro males lighting for the possession of the female, or several male birds displaying their gorgeous plumage, and performing the strangest antics before an assembled body of females, we cannot doubt that, though led by instinct, they know what they are about, and consciously exert their mental and bodily powers. In the same manner 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. Through repeated deadly contests, a slight degree ol variability, if it led to some advantage, how- ever slight, would suffice for the work of sexual selec- tion ; and it is certain that secondary sexual characters 'Chap. VIII. SEXUAL SELECTION. 259 are eminently variable. In the same manner as man can give beauty, according to his standard of taste, to his male poultry— can give to the Sebright bantam a new and elegant plumage, an erect and peculiar carriage- s') it appears that in a state of nature female birds, by having long selected the more attractive males, have added°to their beauty. No doubt this implies powers of discrimination and taste on the part of the female Which will at first appear extremely improbable; but I hope hereafter to shew that this is not the case. From our ignorance on several points, the precise banner in which sexual selection acts is to a certain extent uncertain. Nevertheless if those naturalists i\ho already believe in the mutability of species, will read the following chapters, they will, I think, agree with "ie that sexual selection has played an important part hi the history of the organic world. It is certain that With almost all animals there is a struggle between the 'Dales for the possession of the female. This iact is so Notorious that it would he superfluous to give instances, hloneo the females, supposing that their mental capacity sufficed for the exertion of a choice, conld select, one out °f several males. But in numerous cases it appears as if it had been specially arranged that there should he ", struggle between many males. I bus with migratory birds, the males generally arrive before the females at their place of breeding, so that many males are ready 1° contend for each female. The bird-catchers assert that this is invariably the ease with the nightingale and blackcap, as I am informed by Mr. Jewner W eir, who confirms tbe statement with respect to the latter species. Mr. Swaysland of Brighton, who has been in the habit, during the last forty years, of catching our migratory Mrds on their first arrival, writes to me that he has nf‘,ver known the females of any species to arrive before 260 THE PRINCIPLES OP Part II- their males. During one spring he shot thirty-nine males of Hay’s wagtail (Budytes Baii ) before lie saw tv single female. Mr. Gould has ascertained l>y dissection* as he informs me, that male snipes arrive in this country before the females; but this hardly concerns ns, as snipes do not breed here. In the case of fish, at the period when the salmon ascend our rivers, the males in large numbers are ready to breed before the females- So it apparently is with frogs and toads. Throughout the great class of insects the males almost always emerge from the pupal state before the other sex, so that they generally swarm for a time before any females can be seen.” The cause of this 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 which in the spring were first, ready to breed, or were the most eager, would leave the largest number of offspring ; and these would tend to inherit similar instincts and constitutions. On the whole there can be no doubt that wnh 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 i» understanding how it is that the males which conquer otner males, or those which prove the most attractive to the females, leave a greater number of offspring to inherit their superiority than the beaten and less- 3 Even with those of plants in which the sexes are separate, tho flowers are generally mature before tho female. Many hermaphrodite Plants are, as first shewn by C. li. Sprengel, dichogamous ; that is* their male and female organs are not ready at the same time, so tied they cannot bo self-fertilised. Now with such plants the pollen i*“ generally mature in the same flower before the stigma, though there are some exceptional species in which the female organs are mature- before the male. SEXUAL SELECTION. 261 ^up. vm. 'Attractive males. Unless tills result should follow, the characters which give to certain males an advantage ■°Ver others, conhl not he perfected and augmented through sexual selection. When the sexes exist in exactly equal numbers, the worst-endowerl males will ultimately find females (except where polygamy pre- vails), and leave as many offspring, equally well fitted for their general habits of life, as the best-endowed males, f rom various facts and considerations, I fornieily in- terred that with most animals, in which secondary sexual characters are well developed, the males considerably exceeded the females in number; and this does hold Rood in some few cases. 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 propor- tions of the sexes, I do not believe 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 fitter-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 Mr. Jenner W eir, who has during many years carefully attended to the habits ot birds. There can also be no doubt that the most vigorous, healthy, and best-nourished females would on an average succeed in rearing the largest number of offspring. The males, as we have seen, are generally ■ready to breed before the females ; of the males the 262 THE PRINCIPLES OE Part lit strongest, and with, some species the best armed, drive away the weaker males ; and the former would then unite with the more vigorous and best-nourished fe- males, as these are the first to breed. Such vigorous pairs would surely rear a larger number of offspring than the retarded females, which would be compelled, supposing the sexes to be numerically equal, to unite- with the conquered and less powerful males ; 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 weapons. But in a multitude of cases the males which conquer other males, do not obtain possession of the females, independently of choice on the part 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, as has been actually observed in some cases, that they would at the same time prefer the more vigorous and lively males.4 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 attractive. Such early jiaiis would have the same advantage in reariug off- spring on the female side as above explained, and nearly the same advantage on the male side. And this ap- paiently has sufficed during a long course of generations to add not only to the strength and fighting-powers of * 1 k,ave received information, hereafter to bo givou, to tliis effect With respect to poultry. Even with birds, such as pigeons, which pan tor life the female, as I hear from Mr. Jenner Weir, will desert iior mate it lie is injured or grows weak. CUAP. VIII. SEXUAL SELECTION. 263 the males, but likewise 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 advantage 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 in providing for the young. The same principles would apply if both sexes mutually preferred 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 considerably exceeded in number the females. Hence I was led to investigate, as fai- ns I could, the proportions between the two sexes of ns 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 supplementary dis- cussion, so as not to interfere with the course of my nrgument. Domesticated animals alone afford the opportunity of ascertaining the proportional numbers nt birth ; but no records have been specially kept for this purpose. By indirect means, however, I. have collected a considerable body of statistical data, fiom which it appears that with most of our domestic animals the sexes are nearly equal at birth. .1 hus with race-horses, 25,560 births have been recorded during twenty-one years, and the male births have been to tbe female births as 90-7 to 100. With greyhounds the 264 THE PMNCIPLES OF Part II. inequality is greater than with any other animal, for during twelve years, out of 0878 births, the male births have been as 1 10-1 to 100 female births. It is, however, in some degree doubtful whether it is safe to infer that the same proportional numbers would hold good under natural conditions as under domestication; for slight and unknown differences in the conditions affect to a certain extent the proportion of the sexes. Thus with mankind, the male births in England are as 104-5, m Russia ns 10841, and with the Jews of Livonia as 120 to 100 females. The proportion is also mysteriously affected by the circumstance of the births beirm legiti- mate or illegitimate. Foi our present purpose we are concerned with the proportion of the sexes, not at birth, but at maturity and this adds another element of doubt ; for it is a well ascertained fact that with man a considerably larger proportion of males than of females die before or during birth, and during the first few years of infancy. So it almost certainly is with male lambs, and so it may be with the males of other animals. The males of some animals kill each other by fighting; or they drive each other about until they become greatly emaciated. Iliey must, also, whilst wandering about in eager search for the females, be often exposed to various dangers. With many kinds of fish the males are much smaller than the females, and they are believed often to be devoured by the latter or by other fishes. With some birds the females appear to die in larger proportion than the males: they are also liable to be destroyed on then- nests, or whilst in charge of their young. With insects the female larvm are often larger than those of the males, and would consequently be more likely to be devoured : in some eases the mature females are less active and less rapid in their movements than the males, ■Chap. VIII. SEXUAL SELECTION. 2G5 and would not be so well able to escape from danger. Hence, with animals in a state of nature, in order to judge of the proportions of the sexes at maturity, we must rely on mere estimation ; and this, except perhaps "hen the inequality is strongly marked, is but little trustworthy. Nevertheless, as far as a judgment can he 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, considerably exceed in number the females. bhe proportion between the sexes fluctuates slightly during successive years : thus with race-horses, foi e\ery 100 females born, the males 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 numbers been tabulated throughout a more extensive area than England, these fluctuations would probably have disappeared; and such us they are, they would hardly suffice to lead under u state of nature to the effective action of sexual selec- lion. Nevertheless with some few wild animals, the Proportions seem, as shewn in the supplement, to fluc- luate either during different seasons or in different localities in a sufficient degree to lead to such action. Hor it should be observed that any advantage gained during certain years or in certain localities by those males which were able to conquer other males, oi were the most attractive to the females, would probably be transmitted to the offspring and would not subsequently he eliminated. During the succeeding seasons, when d'orn the equality of the sexes every male was every- where able to procure a female, the stronger or more ^tractive males previously produced would still have least as good a chance of leaving offspring as the strong or less attractive. Polygamy.— The practice of polygamy leads to the 266 THE PRINCIPLES OF Pari U- 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 will not be able to pair; and the latter assuredly will be the weaker or less attractive individuals. Many mammals and sonic few birds are polygamous, but with animals belonging to the lower classes 1 have found no evidence of this habit. The intellectual powers of such animals are, perhaps, not sufficient to lead them to collect and guard a harem of females. That some relation exists between poly- gamy and the development of secondary sexual cha- racters, appears nearly certain; and this supports the view that a numerical preponderance of males would bo eminently favourable to the action of sexual selection- Nevertheless many animals, especially birds, which arc strictly monogamous, display strongly-marked secondary sexual characters ; whilst some few animals, which are polygamous, are not thus characterised. We will first briefly run through the class of mam- ma s, and then turn to birds. The gorilla seems to he a polygamist, and the male differs considerably from the female ; so it is with some baboons which Jive i*1 herds containing twice as many adult females as males, n k" outh America the Mycetes caraya presents well" marked sexual differences in colour, beard, and vocal oigans, and the male generally lives with two or three wiies. the male o t the Cebus capucinus differs some- what 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 i ", ^ °n a’ SilvaSe and Wyman, • Boston Journal of Nat. His*-’ n °n Cynocephalus, Brelun, ‘Illust. TMerleben,’ ‘ 0n Myeetes, Itengger, ‘ Naturgcscli. : Saugethier® von Paraguay,’ 1830, s. 14, 20. On Cebus, Brehm, ibid. s. 108. C«AP. VIII. SEXUAL SELECTION. 2G7 more frequently present sexual differences than almost ahy other group of mammals, especially in their weapons, tut likewise in other characters. Most deer, cattle, and sheep are polygamous ; as are most antelopes, though Some of the ' latter are monogamous. Sir Andrew Smith, in speaking of the antelopes of South Africa, SaJrs that in herds of about a dozen there was rarely more than one mature male, iho Asiatic Ant dope djri appears to he the most inordinate polygamist iu the world; for Pallas6 states that the male drives aWay all rivals, and collects a herd of about a hundred, insisting of females and kids : the female is hornless and has softer hair, but docs not otherwise differ much from the male. The horse is polygamous, but, except 'u his greater size and in the proportions ol his both , differs but little from the mare. The wild boar, in his great tusks and some other characters, presents well- marked sexual characters ; in Europe and in India he ^uds a solitary life, except during the breeding-season ; W at this season he consorts in India with several fmiales, as Sir W. Elliot, who has had large experience 111 observing this animal, believes : whether this holds &»od jn Europe is doubtful, but is supported by some statements. The adult male Indian elephant, like the ^°ar, passes much of his time in solitude ; but when associating with others, “it is rare to find,”, as Dr. Campbell states, “more than one male with a whole " herd of females.” The larger males expel or kill the suialler and weaker ones. The male differs from the tamale by his immense tusks and greater size, strength, and endurance ; so great is the difference in these latter ' f alias, ‘ Spicilcgia Zoolog.’ Fnsc. xii. 1777, p. 20. Sir Andrew maith, > Illustrations of the Zoology of S. Africa,’ 1849, pi. 29, on the _°htts. Owen, in his ‘Anatomy ol Vertebrates (vol. iii. 1818, p. 683) Sffes a table incidentally showing which species of Antelopes pair and lch are gregarious. , 2(38 THE PRINCIPLES OP Past II. respects, that the males when caught are valued at twenty per cent, above the females/ With other pachy- dermatous animals the sexes differ very little or not at all, and they are not, as far as known, polygamists. Hardly a single species amongst the Cheiroptera and Hdentata, or in the great Orders of the Rodents and 1 nsectivora, presents well-developed secondary sexual differences ; and .1 can find no account of any species being polygamous, excepting, perhaps, the common rat, the males of which, as some rat-catchers affirm, live with several females. The lion in South Africa, as I hear from Sir Andrew Smith, sometimes lives with a single female, but gene- ■Lilly with more than one, and, in one case, was found with as many us five females, so that he is polygamous. He is, as far us 1 can discover, the sole polygamist i» the whole group of the terrestrial Carnivora, and he alone presents well-marked sexual characters. If, hoW- em-, we turn to the marine Carnivora, the case is widely different ; for many species of seals offer, as we shall hereafter see, extraordinary sexual differences, and they are, eminently polygamous. Thus the male sea-ele- phant of the Southern Ocean, always possesses, accord- ing to 1’eron, several females, and the sea-lion of Forster is said to be surrounded by from twenty to thirty females- In tlie North, the mule sea-bear of Steller is accom- panied by even a greater number of females. With respect to birds, many species, the sexes 0 which differ greatly from each other, are certainly monogamous. In Great Britain we see well-marked sexual differences in, for instance, the wild-duck which pairs with a single female, with the common blackbird, ' Dr. Campbell, in • Proe. Zoolog. Soc.’ 18G9. p. 13S. See also a11 interesting paper, by Lieut. Johnstone, in ‘Proe. Asiatic Soo. of BengaV May, ibuo. Cbap. viii. SEXUAL SELECTION. 2G9 aUd with the bullfinch which is said to pair for life. So '1 is, as I am informed by Mr. Wallace, with the Chat- terers or Cotingid® of South America, and numerous other birds. In several groups I have not been able to discover whether the species are polygamous or mono- Satnous. Lesson says that birds ot paradise, so re- markable for their sexual differences, are polygamous, Wt Mr. Wallace doubts whether he had sufficient evi- dence. Mr. Salvin informs me that he has been led to believe that humming-birds are polygamous. The !flale widow-bird, remarkable for his caudal plumes, °«rtainly seems to be a polygamist* I have been assured by Mr. Jenner Weir and by others, that three starlingS not rarely frequent the same nest ; but whether this is° a case of polygamy or polyandry has not been Ascertained. The Gallinace® present almost as strongly marked dxual differences as birds of paradise or humming- birds, and many of the species are, as is well known, P°lygamous ; others being strictly monogamous. AY hat a contrast is presented between the sexes of the poly- gamous peacock or pheasant, and the monogamous guinea-fowl or partridge ! Many similar cases could 1)6 given, as in the grouse tribe, in which the males the polygamous capercailzie and black-cock differ greatly fronTthe females ; whilst the sexes of the mono- Samous red grouse and ptarmigan differ very little. 'Wongst the Cursores, no great number ot species °&er strongly - marked sexual differences, except the bustards, and the great bustard ( Otis tarda), is said to , S ‘ The II, is,’ vol. iii. 1861, v 1»3, on the Progno Widow-bird. See als° 0:1 the Vidua axillaris, ibid. vol. ii. I860, p. 211. On the. poly- ga»iy of the Capercailzie and Great Bustard, see L. Lloyd, ‘ Game Birds Sweden,’ 1807, p. 19, and 182. Montagu and Selby speak of the Ufack Grouse as polygamous and of the Red Grouse as monogamous. 270 THE PRINCIPLES OP Pam It be polygamous. With the Grallatores, extremely fe* species differ sexually, but the ruff ( Machetes pugnav) atiords a strong exception, and this species is believed hy Montagu to be a polygamist. Hence it appears that with birds there often exists a close relation between polygamy and the development of strongly- marked sexual differences. On asking Mr. Bartlett at the Zoological Gardens, who has had such large ex- perience with birds, whether the male tragopan (one of the Gallinaceie) was polygamous, 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. Tim wild-duck is strictly monogamous, the domestic-duck highly polygamous. The Rev. W. 1). Fox informs me that with some half-tamed wild-ducks, kept on a large pond m his neighbourhood, so many mallards were slm* by the gamekeeper that only one was left for overt 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.9 Canary-birds pair in a state of nature, but the breeders in England successfully put one male to four or five females ; never- theless the first female, as Mr. Fox has been assured, is alone treated as the wife, she and her young ones being fed by him ; the others are treated as concubines- I have noticed these cases, as it renders it in some degiee probable that monogamous species, in a state of nature, might readily become either temporarily or per- manently polygamous. tv, if • ™7o E‘ S' ,Dl,xon’ however, speaks positively (‘ Ornamental Poultiy, ISIS, p. iG) about the eggs of the guinea-fowl being infertile vhen more than one female is kept with the same male ^hap. vm. SEXUAL SELECTION. 271 With respect to reptiles and fishes, too little is known of their habits to enable us to speak of their marriage arrangements. The stickle-back Gasterosteus), however, is said to be a polygamist ; 10 and the male during the breeding-season differs conspicuously from the female. To sum up on the means through which, as far as ''re can judge, sexual selection has led to the develop- ment of secondary sexual characters. It has been shewn that the largest number of vigorous offspring will be feared from the pairing of the strongest and best-armed males, which have conquered other males, with the most vigorous and best-nourished females, which are the first to breed in the spring. Such females, if they select the more attractive, and at the same time vigorous, males, will rear a larger number of offspring than the retarded females, which must pair with the less vigorous and less attractive males. So it will be ff the more vigorous males select the more attractive mnl at the same time healthy and vigorous females ; a-Hd this will especially hold good if the male defends tho female, and aids in providing food for the young. 'I’he advantage thus gained by the more vigorous pairs l11 rearing a larger number of offspring has apparently sufficed to render sexual selection efficient. But a large Preponderance in number of the males over the females ^offid be still more efficient ; whether the preponder- Ui i co was only occasional and local, or permanent ; whether it occurred at birth, or subsequently from the greater destruction of the females ; or whether it in- directly followed from the practice of polygamy. r 27 ie Male generally more modified than the Female. — throughout the animal kingdom, when the sexes differ w Noel Humphicys, ‘ Kiver Gardens,’ 1857. 272 THE PRINCIPLES OF Paist IT- from each other in external appearance, it is the male which, with rare exceptions, lias been chiefly modified; for the female still remains more like the young of lie* oun species, and more like the other 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 fight together and sedulously display their charms before the females ; and those which are victorious transmit their superiority to their male offspring. Why the males do not transmit their characters to both sexes will hereafter be considered. That the males of all mammals eagerly pursue the females is notorious to every one. So it is with birds ; but many male birds do not so much pursue the female, as display their plumage, perform strange antics, and pour forth their song, in her presence. With the few fish which have been observed, the male seems much more eager than the female; and so it is with alligators, and apparently with Batrachians. Throughout the enormous class of insects, as Kirby remarks,11 “the law is, that the male- “ S^1'|H seek the female.” With spiders and crustaceans, as I hear from two great authorities, Mr. Blackwall and Mr. G. Spence Bate, the males are more active and more enatic in their habits than the females. With insects and crustaceans, when the organs of sense or locomotion are present in the one sex and absent in the other, or when, as is frequently the ease, they are more highly developed in the one than the other, it is almost invariably the male, as far as I can discover, 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.1' 11 Kirby and Spence, ‘ Introduction to Entomology,’ vol. iii. p. 342. ’ 12 0ne pwesifie Bymenopterons insect (Westwood, 1 Modern Cls»ss- ol Insects,’ vot. ii. p. ICO) forms an exception to the rule, as the nial« SEXUAL SELECTION. 273 ■'HAP. VIII. The female, on the other hand, with the rarest excep- tion, is less eager than the male. As the illustrious Hunter18 long ago observed, she generally “requires to ‘‘be courted;” she is coy, and may often be seen en- deavouring for a long time to escape from the male. Every one who has attended to the habits of animals "’ill be able to call to mind instances of this kind, •■fudging from various facts, hereafter to be given, and Horn the results which may fairly be attributed to sexual selection, the female, though comparatively Passive, generally exerts some choice and accepts one ^ale in preference to others. Or she may accept, as "Ppearances would sometimes lead us to believe, not Hie male which is the most attractive to her, but the °He which is the least distasteful. The exertion of s°tne choice on the part of the female seems almost as general a law as the eagerness of the male. We are naturally led to enquire why the male in so 5nany and such widely distinct classes has been ren- dered more eager than the female, so that lie searches ■°r her and plays the more active part in courtship. H would he no advantage and some loss of power if both sexes were mutually to search for each other ; hut "liy should the male almost always be the seeker ? With plants, the ovules after fertilisation have to be “nurislied for a time; lienee the pollen is necessarily brought to the female organs — being placed on the ®tigma, through the agency of insects or ol the wind, Jlns rudimentary wings, and never quits tlio cell in wkicli it is born, "hilst the female has well-developed wings. Andouin believes that lc-‘ females arc impregnated l>v the moles width arc born in the same with them; but it is much more probable that the females visit ’‘ther celj^ and thus avoid close interbreeding. We shall hereafter ^W'et with a few exceptional eases, in various classes, in which the eniale, instead of the male, is the seeker and wooer. 4 Essays and Observations/ edited by Owen, vol. i. 1801, p. 191. VOL. I. T 274 THE PRINCIPLES OF Part II1- or by tbe spontaneous movements of the stamens ; and1 with the Algae, &c., by the locomotive power of the antherozooids. With lowly-organised animals perma- nently affixed to the same spot and having their sexes separate, the male element is invariably brought to the female ; and we can see the reason why ; for the ova, even if detached before being fertilised and not requiring subsequent nourishment or protection, would be, from their larger relative size, less easily transported than the male element. Hence plants 14 and many of the lower animals are, in this respect, analogous. The males of affixed animals having been thus led to emit their fertilising element, it is natural that any of their descendants, which rose in the scale and became loco- motive, should retain the same habit, and should closely approach the female, so that the fertilising element might not run the risk of a long transit through the waters of the sea. With some few of the lower ani- mals, the females alone are fixed, and with these the males must be the seekers. With respect to forms, of which the progenitors were primordially free, it is difficult to understand why the males should inva- riably have acquired the habit of approaching the females, instead of being approached by them. But in all cases, in order that tire males should be efficient seekers, it would be necessary that they should be en- dowed with strong passions ; and the acquirement 04 such passions would naturally follow from the more eager males leaving a larger number of offspring than the less eager. The great eagerness of the male has thus indirectly 14 Prof. Sachs Lehrbucli tier Botanik,’ 1870, s. 633) in speaking the male and female reproductive cells, remarks, “ verlialt sick die eiB0 “ bei der Vereinigung activ, ... die andere erscheint bei dor VereiB" ignng passiv.” °HAP. VIII. SEXUAL SELECTION. 275 i®d to tlie mueli more frequent development of secon- dary sexual characters in the male than in the female, dint the development of such characters will have been much aided, if the conclusion at which I arrived after Undying domesticated animals, can be trusted, namely, that the male is more liable to vary than the female, d am aware how difficult it is to verify a conclusion of this kind. Some slight evidence, however, can be gained V comparing the two sexes in mankind, as man has deen more carefully observed than any other animal, during the Novara Expedition 15 a vast number of mea- s,U'ements of various parts of the body in different races "’ere made, and the men were found in almost every °ase to present a greater range of variation than the "’omen; but I shall have to recur to this subject in a future chapter. Mr. J. Wood,10 who has carefully ^tended to the variation of the muscles in man, puts 111 italics the conclusion that “ the greatest number of abnormalities in each subject is found in the males.” Jde had previously remarked that “altogether in 102 subjects the varieties of redundancy were found to ,£ de half as many again as in females, contrasting " widely with the greater frequency of deficiency in “ females before described.” Professor Macalister like- wise remarks17 that variations in the muscles “are Probably more common in males than females.” Certain muscles which are not normally present in man- viud are also more frequently developed in the male tdan in the female sex, although exceptions to this rule 1,1 ‘Reise der Novara: Antbropolog. Tkeil,’ 1807, s. 216-269. The j?sults were calculated by Dr. Weisbaoh from measurements made by .! R. Sckerzcr and Schwarz. On the greater variability of the males 1 domesticated animals, see my ‘ Variation of Animals and Plants Vr domestication,’ vol. ii. 1S68, p. 75. 1? ‘Proceedings Royal Soe.’ vol. xvi. July, 1868, p. 519 and 52-1. 1 Rroc. Royal Irish Academy,’ vol. x. 18G8, p. 123. T 2 276 THE PRINCIPLES OF Part II- are said to occur. Dr. Burt Wilder18 lias tabulated the cases of 152 individuals with supernumerary digits of which 8b were males, and 39, or less than half, females; the remaining 27 being of unknown sex. It should not, however, be overlooked that women would more frequently endeavour to conceal a deformity of this kind than men. Whether the large proportional number of deaths of the male offspring of man and apparently of sheep, compared with the female offspring) before, during, and shortly after birth (see supplement)) has any relation to a stronger tendency in the organs of the male to vary and thus to become abnormal iu structure or function, I will not pretend to conjecture. In various classes of animals a few exceptional cases occur, in which the female instead of the male has acquired well pronounced secondary sexual characters, such as brighter colours, greater size, strength, or pug' nacity. With birds, as Mre shall hereafter see, there has sometimes 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 select' iug, as we may infer from the results, the more attractive females. Certain female birds have thus been rendered more highly coloured or otherwise ornamented, as well as more powerful and pugnacious than the males, 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; the males having 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, 18 ‘Massachusetts Medical Soc.’ vol. ii. No. o, 1808, p. 9. CltAP. VIII. SEXUAL SELECTIOX. 277 "’°uld not make the one sex different from the other, Unless indeed their taste for the beautiful differed ; but this is a supposition too improbable in the case of any tUlhnal, excepting man, to be worth considering. There ate, however, many animals, in which the sexes resemble each other, both being furnished with the same orna- ments, which analogy would lead us to attribute to the agency of sexual selection. In such cases it may be suggested with more plausibility, that there has been a double or mutual process of sexual selection ; the more vigorous and precocious females having selected the more attractive anil vigorous males, the latter having mjected all except the more attractive females. But h‘°m what we know of the habits of animals, this view 18 hardly probable, the male being generally eager to Pair with any female. It is more probable that the °l’naments common to both sexes were acquired by one generally the male, and then transmitted to the off- ering of both sexes. If, indeed, during a lengthened Pei'iod the males of any species were greatly to exceed the females in number, and then during another engthened period under different conditions the reverse "ere to occur, a double, but not simultaneous, process sexual selection might easily be carried on, by which the two sexes might be rendered widely different. We stall hereafter see that many animals exist, of "hich neither sex is brilliantly coloured or provided " 'Hi special ornaments, and yet the members of both 8exes or of one alone have probably been modified dirough sexual selection. The absence of bright tints other ornaments may bo the result of variations of Hie right kind never having occurred, or of the animals themselves preferring simple colours, such as plain black Ul white. Obscure colours have often- been acquired u'ough natural selection for the sake of protection, and 278 THE PRINCIPLES OP Part li- the acquirement through sexual selection of conspicuous colours, may have been checked from the danger thus incurred. But in other cases the males have probably struggled together during long ages, through brute force, or by the display of their charms, or by both means combined, and yet no effect will have been pro* duced unless a larger number of offspring were left by the more successful males to inherit their superiority, than by the less successful males ; and this, as previously shown, depends on various 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 success- ful male merely fails to obtain a female, or obtains a retarded and less vigorous female later in the season, or, if polygamous, obtains fewer females ; so that they leave fewer, or less vigorous, or no offspring. In re- gaid to structures acquired through ordinary or natural selection, there is in most cases, as long as the condi- tions of life remain the same, a limit to the amount of advantageous modification in relation to certain special ends ; but in regard to structures adapted to make one male victorious over another, either in fighting or i» charming the female, there is no definite limit to the amount of advantageous modification ; so that as long & the proper variations arise the work of sexual selection will go on. This circumstance may partly account for the frequent and extraordinary amount of variability presented by secondary sexual characters. Nevertheless, natural selection will determine that characters of this kind shall not be acquired by the victorious malts, which would be injurious to them in any high degree, either by expending too much of their vital powers, or 'Ciur, VIII. SEXUAL SELECTION. 279 by exposing them to any great danger. The develop- ment, however, of certain structures — of the horns, for instance, in certain stags — has been carried to a "underfill extreme; and in some instances 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 have derived from conquering other males in battle or courtship, and thus leaving a Numerous progeny, have been in the long run greater than those derived from rather more perfect adaptation to the external conditions of life. We shall further see, and this could never have been anticipated, that the power to charm the female has been in some few in- stances more important than the power to conquer other- males in battle. LAWS OF INHERITANCE. In order to understand how sexual selection has uoted, and in the course of ages has produced conspicuous faults with, many animals of many classes, it is neces- sary to bear in mind the laws of inheritance, as far as they are known. Two distinct elements are included Under the term “ inheritance,” namely the transmission -and the development of characters; but as these generally go together, the distinction is often over- looked. * We see this distinction in those characters "'hick are transmitted through the early years ot life, hut 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 iu one alone. That they are present in both sexes, is manifest when two species, having strongly-marked sexual characters, ■are crossed, for each transmits the characters proper to 280 THE PRINCIPLES OP Part II- its own male and female sex to the hybrid offspring of either sex. The same fact is likewise manifest, when characters proper to the male are occasionally deve- loped in the female when she grows old or becomes diseased; and so conversely with the male. Again, clnu actors occasionally appear, as if 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 in the structure of the spur is transmitted through the female to her male offspring. In all cases of reversion, characters aie transmitted through two, three, or many generations- and are then under certain unknown favourable con- ditions developed. This important distinction between transmission and development will be easiest kept in mind by the aid of the hypothesis of pangenesis, whether or not it be accepted as true. According to this hypo- thesis, every unit or cell of the body throws off gemmules 01 undeveloped atoms, which are transmitted to the offing of both sexes, and are multiplied by self- division. I hey may remain undeveloped during the early years of life or during successive generations," their development into units or cells, like those from which they were derived, depending on their affinity for, and uuion with, other units or cells previously developed in the due order of growth. Inheritance at Corresponding Periods of Life.— This- tendency is well established. I f a new character appears in an animal whilst young, whether it endures through- out life or lasts only for a time, it will reappear, as » general rule, at the same age and in the same manner m the offspring. If, on the other hand, a new character appears at maturity, or even during old age, it tends- C«AP. VIII. SEXUAL SELECTION. 281 to reappear in tire offspring at the same advanced age. When deviations from this rule occur, the transmitted characters much oftener appear before than after the corresponding a ire. As I have discussed this subject at sufficient length in another work,11’ I will here merely give two or three instances, for the sake ot recalling the subject to the reader’s mind. In several breeds of the Fowl, the chickens whilst covered with down, the young birds in their first true plumage and in their adult plum- age, differ greatly from each other, as well as from their common parent-form, the Gallus lanldm ; and these characters are faithfully transmitted by each breed to their offspring at the corresponding period of life. For instance, the chickens of spangled Hamburghs, whilst covered with down, have a few dark spots oil the head and rump, but are not longitudinally striped, as in niany other breeds ; in their first true plumage, “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 0r tipped with a dark round spot.20 Hence in this breed variations have occurred and have been trans- mitted at three distinct periods of life. The Pigeon offers a more remarkable case, because the aboriginal parent- species does not undergo with advancing age any change °f plumage, excepting that at maturity the breast becomes more iridescent; yet there are breeds which do not acquire their characteristic colouis until thej 19 ‘The Variation of Animals and Plants under Domestication’ voL li- 1868, p. 75. In the la>t chapter but one, the provisional hypothesis pangenesis, above alluded to, is fully explained. „ :u These facts are given on the high authority of a great breeder, ®r- Teebay, in Tegetmeier’s ‘Poultry Boole,’ 1868, p. 158. On the characters of chickens of different breeds, and on the breeds of the h'geon, alluded to in the above paragraph, see ‘ Variation of Animals," &c., vol. i. p. ICO, 249 ; vol. ii. p. 77. 282 THE PEIHCIP1ES OF Part II- lia-'e moulted two, three, or four times ; and these modifications of plumage are regularly transmitted. Inheritance at Corresponding Seasons of the Year- ~ ^ animals in a state of nature innumerable instances occur of characters periodically appearing at different seasons. We see this with the horns of the stiig, and with the fur of arctic animals which becomes , thick and white during the winter. Numerous birds acquire bright colours and other decorations during the breeding-season alone. I can throw but little light on this form of inheritance from facts observed under domestication. Pallas states,21 that in Siberia domestic cattle and horses periodically become lighter-coloured during the winter; and I have observed a similar marked change of colour in certain ponies in England. Although I do not know that this tendency to assume a differently coloured coat during different seasons of the year is transmitted, yet it probably is so, as all shades of colour are strongly inherited by the horse. Nor is this orm of inheritance, as limited by season, more remark- able than inheritance as limited by age or sex. Inheritance as limited by Sex. — The equal trans- mission of characters to both sexes is the commonest form of inheritance, at least with those animals which do not present strongly-marked sexual differences, and indeed with many of these. But characters are not rarely transferred exclusively to that sex, in which they fiist appeared. Ample evidence on this head has been advanced in my work on Variation under Domestics -1 ‘Novas species Qnadrupedmn e Glirium ordine,’ 1778 p 7 On the trausm^ion of colour by the home, sec ‘ Variation of Animals, &«• umlci Domestication, vol. i. p. 51. Also vol. ii. p. 71, for a general -discussion on Inheritance us limited by Sox. Chap. VIII. SEXUAL SELECTION. 283 tion ; but a few instances may here be given. There are breeds of the sheep and goat, in which the horns °f the male differ greatly in shape from those of the female; and these "differences, acquired under domes- tication, are regularly transmitted to the same sex. With tortoise-shell cats the females alone, as a general rule, are thus coloured, the males being rusty-red. With most breeds of the fowl, the characters proper to each sex are transmitted to the same sex alone, feo general is this form of transmission that it is an ano- maly when we see in certain breeds variations trans- mitted equally to both sexes. There are also certain sub-breeds of” the fowl in which the males can hardly ho distinguished from each other, whilst the females differ considerably in colour. With the pigeon the sexes of the parent-species do not differ in any external character; nevertheless in certain domesticated breeds We male is differently coloured from the female.22 The wattle in the English Carrier pigeon and the crop in the Pouter are more highly developed in the male Wan in the female; and although these characters have been gained through long-continued selection by man, We difference between the two sexes is wholly due to die form of inheritance which lias prevailed; for it has arisen, not from, hut rather in opposition to, the wishes of the breeder. , Most of our domestic races have been formed by the accumulation of many slight variations ; and as some of the successive steps have been transmitted to one alone, and some to both sexes, we find m the diffe- I'ent breeds of the same species all gradations between gloat sexual dissimilarity and complete similarity. In- 22 Dr. Cliapuis, ‘Le Pigeon Voyagcnr Beige,’ 1865, p. 87. Boitard Corbie, ‘Les Pigeons de Voliere/ &c., 1824, p. 1/3. 284 THE PEINCIPLES OF Part II- stances have already been given with the breeds of the o'v and pigeon , and under nature analogous cases are ot frequent occurrence. With animals under domesti- cation, but whether under nature I will not venture to say, one sex may lose characters proper to it, and may t ms come to resemble to a certain extent the opposite sox; for instance, the males of some breeds of the fowl have lost their masculine plumes and hackles. On the other hand the differences between the sexes may he increased under domestication, as with merino sheep, in which the ewes have lost their horns. Again, characters piopci to one sex may suddenly appear in the other sex; as with those sub-breeds of the fowl in which the hens whilst young acquire spurs ; or, as in certain lohsh sub-breeds, in which the females, as there is reason to believe, originally acquired a crest, and sub- sequently transferred it to the males. All these cases are intelligible on the hypothesis of pangenesis; for they depend on the gemmules of certain units of the body, although present in both sexes, becoming through the influence of domestication dormant in the one sex ; 01 it naturally dormant, becoming developed. There is one difficult question which it will be con- venient to defer to a future chapter ; namely, whether a character at first developed in loth sexes, can be ren- dered through selection limited in its development to one sex alone. . If, lor instance, a breeder observed that some of his pigeons (in which species characters arc usually transferred in an equal degree to both sexes) varied mto pale blue; could he by long-continued selection make a breed, in which the males alone should e o( this tint, whilst the females remained unchanged ? . * here only say, that this, though perhaps not impossible, would he extremely difficult ; for the natural result of breeding from the pale-blue males would be C«AI>. VIII. SEXUAL SELECTION. 285 to change his whole stock, including both sexes, into this tint. If, however, variations of the desired tint appeared, which were from the first limited in their development to the male sex, there would not he the least difficulty in making a breed characterised by the two sexes being of a different colour, as indeed has been effected with a Belgian breed, in which the males alone are streaked with black. In a similar manner, if any Variation appeared in a female pigeon, which was lrom the first sexually limited in its development, it would be easy to make a breed with the females alone thus characterised ; but if the variation was not thus originally limited, the process would be extremely difficult, per- haps impossible. On the Relation between the period of Development of a Character and its transmission to one sex or to both sexes. ' — Why certain characters should be inherited by both sexes, and other characters by one sex alone, namely by that sex in which the character first appeared, is in most cases quite unknown. We cannot even conjecture why "ith certain sub-breeds of the pigeon, black stria), though transmitted through the female, should ho developed in the male alone, whilst every other character is equally transferred to both sexes. Why, again, with cats, the tortoise-shell colour should, with rare exceptions, be developed in the female alone. The very same cha- racters, such as deficient or supernumerary digits, colour- blindness, &e., may with mankind be inherited by the dales alone of one family, and in another family by the females alone, though in both cases transmitted through the opposite as well as the same sex.”1 Although w'e ore thus ignorant, two rules often hold good, namely References arc given in my ‘ Variation of A-nimnls under Domes- “cation,’ vol. ii. p. 72. 280 THE PRINCIPLES OF Pari II- tliat variations which, first appear in either sex at a late period of life, tend to be developed in the same sex alone ; whilst variations which first appear early in life in either sex tend to be developed in both sexes. I aur? however, far from supposing that this is the sole de- termining cause. As I have not elsewhere discussed this subject, and as it has an important bearing on sexual selection, I must here enter into lengthy and somewhat intricate details. It is in itself probable that any character appearing at an early age would tend to be inherited equally by both sexes, for the sexes do not differ much in constitu- tion, before the power of reproduction is gained. On the other hand, after this power has been gained and the sexes have come to differ in constitution, the gemmules (if I may again use the language of pangenesis) which are cast off from each varying part in the one sex would be much more likely to possess the proper affinities for uniting with the tissues of the same sex, and thus becoming developed, than with those of the opposite sex. I was first led to infer that a relation of this kind exists, from the fact that whenever and in whatever manner the adult male has come to differ from the adult female, he differs in the same manner from the young of both sexes. The generality of this fact is quite remarkable: it holds good with almost all mammals# birds, amphibians, and fishes; also with many crus- taceans, spiders and some few insects, namely certain orthoptera and libellulm. In all these cases the varia- tions, through the accumulation of which the male ac- quired his proper masculine characters, must have oc- curred at a somewhat late period of life ; otherwise the young males would have been similarly characterised ; and conformably with our rule, they are transmitted to CnAr. yni. SEXUAL SELECTION. 287 and developed in the adult males alone. When, on the other hand, the adult male closely resembles the young of both sexes (these, with rare exceptions, being alike), he generally resembles the adult female ; and in most of these cases the variations through which the young and old acquired their present characters, probably occurred hi conformity with our rule during youth. Lilt there is here room for doubt, as characters are sometimes trans- ferred to the offspring at an earlier age than that at 'vhich they first appeared in the parents, so that the parents may have varied when adult, and have trans- ferred their characters to their offspring whilst young. There are, moreover, many animals, in which the two •S(-*Xes closely resemble each other, and yet both differ from their young ; and here the characters of the adults "mst have been acquired late in life ; nevertheless, these characters in apparent contradiction to our rule, aje transferred to both sexes. We must not, however, °verlook the possibility or even probability of succes- sive variations of the same nature sometimes occurring, '"ider exposure to similar conditions, simultaneously in hoth sexes at a rather late period of life ; and in this case the variations would be transferred to the offspring of hoth sexes at a corresponding late age ; and there would he no real contradiction to our rule ot the variations "’hich occur late in life being transferred exelusiv ely to fhe sox in which they first appeared, 'this latter rule 8eems to hold true more generally than the second rule, finely, that variations which occur in either sex early hi life tend to be transferred to both sexes. As it was obviously impossible even to estimate in how large a "Umber of cases throughout the animal kingdom these l)Vo propositions hold good, it occurred to me to inves- %ate some striking or crucial instances, and to rely 011 the result. 288 THE PRINCIPLES OF Part II- An excellent case for investigation is afforded by the Deer Family. In all the species, excepting one, the horns are developed in the male alone, though certainly transmitted through the female, and capable of occasional abnormal development in her. In the reindeer, on the other hand, the female is provided with horns; so that in this species, the horns ought, according to our rule* to appear early in life, long before the two sexes bad arrived at maturity and had come to differ much in constitution. In all the other species of deer the horns ought to appear later in life, leading to their develop- merit in that sex alone, in which they first appeared in the progenitor of the whole Family. Now in seven species, belonging to distinct sections of the family and inhabiting different regions, in which the stags alone bear horns, I hud that the horns first appear at periods varying from nine months after birth in the roebuck t0 ten or twelve or even more months in the stags of the six other larger species.24 But with the reindeer the case is widely different, for as I hear from Prof. Nilsson, who kindly made special enquiries for me in Lapland, the horns appear in the young animals within four or five weeks after birth, and at the same time in both sexes. So that here we have a structure, developed nt a most unusually early age in one species of the family* and common to both sexes in this one species. In several kinds of antelopes the males alone ai'O " 1 I much obliged to Mr. Cupples for having made enquiries 1' 1 me iu regard to the Roebuck and Red Deer of Scotland from h1' Robertson, the experienced head-forester to the Marquis of Breadalbane- In regard to Fallow-deer, I am obliged to Mr. Eyton and others f°r information. For the Cervus alces of N. America, son ‘ Land and Water- 1868, p. 221 and 201 ; and for the C. Virginianns and strongijloceros the same continent, see J. D. Caton, in ‘ Ottawa Acad, of Nat. Sc- 186$, p. 13. For Census Eldl of Pegu, sec Lieut. Beavan, 1 Proc- Zoolog. Soc.’ 1867, p. 762. CiIAP. VIII. SEXUAL SELECTION. 289 Provided with horns, whilst in the greater number both 8exes have horns. With respect to the period of de- velopment, Mr. Blyth informs me that there lived at one time in the Zoological Gardens a young koodoo (- Ant . strepsiceros), in which species the males alone ctl'e horned, and the young of a closely-allied species, viz. the eland (Ant. oreas), in which both sexes are Wned. Now in strict conformity with our rule, in the y°ung male koodoo, although arrived at the age of ten Months, the horns were remarkably small considering the size ultimately attained by them: whilst in the y°ung male eland, although only three months old, the Wns were already very much larger than in the koodoo, ft is also worth notice that in the prong-horned antelope,23 111 which species the horns, though present in both SeXes, are almost rudimentary in the female, they do not aPpear until about five or six months after birth. With shoep, goats, and cattle, in which the horns are well 'Weloped in both sexes, though not quite equal in size, tlley can be felt, or even seen, at birth or soon after- wards.20 Our rule, however, fails in regard to some ^eeds of sheep, for instance merinos, in which the rams al°ne are horned ; for I cannot find on enquiry,27 that ... 5 Antilocapra Americana. Owen, ‘Anatomy of Vertebrates, vol. Ul- P- G27. * I have been assured tbat the horns of the sheep in North Wales lu'.1 ah'avs felt, and are sometimes even an inch in length, at birth. J ltl\ cattle Youatt says (‘ Cattle,’ 1834, p. 277) that the prominence of j2 lrontal hone penetrates the cutis at hirtb, and that the horny l27er h soon formed over it. j i am greatly indebted to Prof. Victor Carus for having made ^dairies for me, from the highest authorities, with respect to the ri'10 sheep of Saxony. On the Guinea coast ot Africa there is a ^ Of sheep in which, as with merinos, the rams alone bear horns; Vo VVinwuod Itcade informs me that in the one case observed, a tji1Jng ram born on Feb. 10th first showed boras on March 6th, so ut in this instance the development of the horns occurred at a later V°L. I. U 290 THE PEINCIPLES OP Part li- the horns are developed later in life in this breed than in ordinary sheep in which both sexes are horned. But with domesticated sheep the presence or absence of horns is not a firmly fixed character ; a certain proportion of the merino ewes bearing small horns, and some of the rams beiug hornless ; whilst with ordinary sheep hornless ewes are occasionally produced. In most of the species of the splendid family of the Pheasants, the males differ conspicuously from the females, and they acquire their ornaments at a rather late period of life. The eared pheasant (Crossopi&M* auritum), however, offers a remarkable exception, for both sexes possess the fine caudal plumes, the large e»r' tufts and the crimson velvet about the head ; and I find on enquiry in the Zoological Gardens that all these characters, in accordance with our rule, appear very' early in life. The adult male can, however, be distin- guished from the adult female by one character, namely by the presence of spurs ; and conformably with our rule, these do not begin to be developed, as I am assured by Mr. Bartlett, before the age of six mouths, and eveu at this age, can hardly be distinguished in the two sexes.28 The male and female Peacock differ con- period of life, conformably with our. rule, than in the Welch sheep, lP which botli sexes are horned. 28 In the common peacock ( Pavo cristatus ) the male alone spurs, whilst botli sexes of the Java peacock (P. mutiem) unusual case of being furnished with spurs. Henco I fully that in the latter species they would havo been developed earl than in the common peacock ; but M. llcgt of Amsterdam informs that with young birds of the previous year, belonging to both spficje~' compared on April 23rd, 1869, there was no difference in the doveW’ mont of the spurs. The spurs, however, were as yet represented merf I by slight knobs or elevations. I presume that I should have been u* formed if any difference in the rate of development had subsequen • been obseryed. posse offer expect c* icr in 11 C cbap. VIII. SEXUAL SELECTION. 291 spicuously from each other in almost every part of their plumage, except in the elegant head-crest, which is common to both sexes ; and this is developed very early m life, long before the other ornaments which are con- fined to the male. The wild-duck offers an analogous case, for the beautiful green speculum on the wings is common to both sexes, though duller and somewhat smaller in the female, and it is developed early in life, whilst the curled tail-feathers and other ornaments peculiar to the male are developed later.31 Between 8Uch extreme cases of close sexual resemblance and wide dissimilarity, as those of the Crossoptilou and Peacock, many intermediate ones could be given, in which the characters follow in their order of develop- ment our two rules. As most insects emerge from their pupal state in a mature condition, it is doubtful whether the period of development determines the transference of their cha- mbers to one or both sexes. But we do not know that tfie coloured scales, for instance, in two species of but- lerflies, in one of which the sexes differ in colour, whilst m the other they are alike, are developed at the same mlative age in the cocoon. Nor do we know whether fdl the scales are simultaneously developed on the wings 22 la some other species of the Duck Family the speculum in the sexes differs in a greater degree ; but I have not been able to dis- c°ver whether its full development occurs later in life in the males of Slleh species, than in the male of the common duck, as ought to be the J*8* according to our rule. With the allied Mergus cueuUatiis we have, °Wever, a case of this kind : the two sexes differ conspicuously in j^Uerai plumage, and to a considerable degree in the speculum, which ^ Pure white in the male and greyish- white in the female. Now the 5°Uiig males at first resemble, in all respects, the female, and have a ^reyish-white speculum, hut this becomes pure white at an earlier age aii that at which the adult male acquires his other more strongly- lurked sexual differences in plumage : see Audubon, * Ornithological l0graphy,’ vol. iii. 1835, p, 243-250. u 2 292 THE PKINCIPLES OF Past It of the same species of butterfly, in which certain coloured marks are confined to one sex, whilst other marks are common to both sexes. A difference of this kind in the period of development is not so improbable as it may at first appear ; for with the Orthoptera, which assume their adult state, not by a single metamorphosis, but by a succession of moults, the young males of some species at first resemble the females, and acquire their distinc- tive masculine characters only during a later moult. Strictly analogous cases occur during the successive moults of certain male crustaceans. We have as yet only considered the transference of characters, relatively to their period of development, with species in a natural state; we will now turn to domes* ticated animals ; first touching on monstrosities and diseases. The presence of supernumerary digits, and the absence of certain phalanges, must be determined at an early embryonic period — the tendency to profuse bleeding is at least congenital, as is probably colour* blindness — yet these peculiarities, and other simil»r ones, are often limited in their transmission to one seS > so that the rule that characters which are developed at an early period tend to be transmitted to both sexes* here wholly fails. But this rule, as before remarked) does not appear to be nearly so generally true as the converse proposition, namely, that characters which appear late in life in one sex are transmitted exclu* sively to the same sex. From the fact of the above abnormal peculiarities becoming attached to one seS> long before the sexual functions are active, we may infer that there must be a difference of some kiud between the sexes at an extremely early age. With respect to sexually-limited diseases, we know too little of the period at which they originate, to draw an) fair conclusion. Gout, however, seems to fall under C«A1>. VIII. SEXUAL SELECTION. 293 °Ur rule; for it is generally caused by intemperance after early youth, and is transmitted from the father t° his sons in a much more marked manner than to his daughters. Iu the various domestic breeds of sheep, goats, and battle, the males differ from their respective females m the shape or development of their horns, forehead, . mane, dewlap, tail, and hump on the shoulders; and fliese peculiarities, in accordance with our rule, are not fully developed until rather late in life. With dogs, Hie sexes do not differ, except that in certain breeds, especially in the Scotch deer-hound, the male is much Wger and heavier than the female ; and as we shall see m a future chapter, the male goes on increasing in size f° an unusually late period of life, which will account, ^cording to our rule, for his increased size being trans- mitted to his male offspring alone. On the other hand, file tortoise-shell colour of the hair, which is confined f° female cats, is quite distinct at birth, and this case ^elates our rule. There is a breed of pigeons in which flic males alone are streaked with black, and the streaks Can be detected even in the nestlings ; but they become more conspicuous at each successive moult, so that this case parti v opposes and partly supports the rule. \\ itli file English Carrier and Pouter pigeon the full develop- ment of the wattle and the crop occurs rather late in fife, and these characters, conformably with our rule, m® transmitted in full perfection to the males alone, •file following cases perhaps come within the class pre- viously alluded to, iu which the two sexes have varied m the same manner at a rather late period of life, and hiive consequently transferred their new characters to f^-th sexes at a corresponding late period ; and if so, SU('h cases are not opposed to onr rule. Thus there ai'e sub-breeds of the pigeon, described by Neumeis- 294 THE PBINCIPLES OP Part II- ter,“° both sexes of which change colour after moulting twice or thrice, as does likewise the Almond Tumbler ; nevertheless these changes, though occurring rather late in life, are common to both sexes. One variety of the Canary-bird, namely the London Prize, offers a nearly analogous case. With the breeds of the Fowl the inheritance of various characters by one sex or by both sexes, seems generally determined by the period at which such characters are developed. Thus in all the many breeds in which the adult male differs greatly in colour from the female and from the adult male parent-species, he differs from the young male, so that the newly acquired characters must have appeared at a rather late period of life. On the other hand with most of the breeds in which the two sexes resemble each other, the young are coloured in nearly the same manner as their parents, and this renders it probable that their colours first appeared earlv in life. We have instances of this fact in all black and white breeds, in which the young and old of both sexes are alike ; nor can it be maintained that there is something peculiar in a black or white plumage, leading to its transference to both sexes ; for the males alone of many natural species are either black or white, the females being very differently coloured. With the so-called Cuckoo sub-breeds of the fowl, in which the feathers are transversely pencilled with dark stripes, both sexes and the chickens are coloured in nearly the same manner- The laced plumage of the Sebright bantam is the same in both sexes, and in the chickens the feathers are tipped with black, which makes a near approach to lacing- Spangled Hamburghs, however, offer a partial exception) 30 ‘Das Ganze der Tanbenzucht,’ 1837, s. 21, 24. For the case <4 the streaked pigeons, see Dr. Cliapuis, ‘Le Pigeon Vo3rageur Bel gc, X8G5, p. 87. Chap. VIII. SEXUAL SELECTION. 205 for the two sexes, though not quite alike, resemble each other more closely than do the sexes of the aboriginal Parent-species, yet they acquire their characteristic Plumage late in life, for the chickens are distinctly pencilled. Turning to other characters besides colour : the males alone of the wild parent-species and of most domestic breeds possess a fairly well developed comb, but in the young of the Spanish fowl it is largely developed at a very early age, and apparently in consequence ot this it is of unusual size in the adult lemales. In the Game breeds pugnacity is developed at a wonderfully early age, of which curious proofs could be given ; and this character is transmitted to both sexes, so that the hens, from their extreme pugnacity, are now generally exhibited in separate pens. With the Polish breeds the bony protuberance of the skull which supports the crest is partially developed even before the chickens are hatched, and the crest itself soon begins to grow, though at first feebly ; 31 and in this breed a great bony protu- berance and an immense crest characterise the adults of both sexes. Finally, from what we have now seen of the relation which exists in many natural species and domesticated l’aces, between the period of the development of their characters and the manner of their transmission for Example the striking fact of the early growth of the horns in the reindeer, in which both sexes have horns, >u comparison with their much later growth in the other species in which the male alone beais horns 31 For full particulars and references on all these points respecting he several breeds of the Fowl, see ‘Variation of Animals and Plants Under Domestication,’ vol. i. p. 2-50, 250. In jegaid to the higher Wiirnala, the sexual differences which have arisen under domestication ate described in the same work under the head of each species. 296 THE PBINCIPLES OF Pari If we may conclude that one cause, though not the sole cause, of characters being exclusively inherited bv one sex, is their development at a late age. And secondly, that one, though apparently a less efficient, cause of characters being inherited by both sexes is their deve- lopment at an early age, whilst the sexes differ but little in constitution. It appears, however, that sour© difference must exist between the sexes even during an early embryonic period, for characters developed at°this age not rarely become attached to one sex. Summary and concluding remarks. — From the fore- going discussion on the various laws of inheritance, we learn that characters often or even generally tend to become developed in the same sex, at the same age, and periodically at the same season of the year, in which they first appeared in the parents. But these laws, from unknown causes, are very liable to change. Hence the successive steps in the modification of a species might readily be transmitted in different ways; some of the steps being transmitted to one sex, and some to both ; some to the offspring at one age, and some at all ages. Not only are the laws of inherit- ance extremely complex, but so are the causes which induce and govern variability. The variations thus caused are preserved and accumulated by sexual selec- tion, which is in itself an extremely complex affair, depending, as it does, on ardour in love, courage, and the rivalry of the males, and on the powers of percep- tion, taste, and will of the female. Sexual selection will also be dominated by natural selection for the general welfare of the species. Hence the manner in which the individuals of either sex or of both sexes are affected through sexual selection cannot fail to be complex in the highest degree. ciUp. VIII. SEXUAL SELECTION. 297 When variations occur late in life in one sex, and are transmitted to the same sex at the same age, the other sex and the young are necessarily left unmodified. When they occur late in life, but are transmitted to koth sexes at the same age, the young alone are left un- modified. Variations, however, may occur at any period of life in one sex or in both, and be transmitted to both spXes at all ages, and then all the individuals of the species will be similarly modified. In the following chapters it will be seen that all these cases frequently °ccur under nature. Sexual selection can never act on any animal be- fore the age for reproduction has arrived. From the great eagerness of the male it has generally acted on this sex and not on the females. The males We thus become provided with weapons for fight- Ojg with their rivals, or with organs for discovering aud securely holding the female, or for exciting and charming her. When the sexes differ in these respects, ]t is also, as we have seen, an extremely general law tl»at the adult male differs more or less from the young male; and we may conclude from this fact that the Recessive variations, by which the adult male became modified, have not generally occurred much before the for reproduction. Whenever some or many of the Variations have occurred early in liie, the young males "nil partake in a less or greater degree of the dia- meters of the adult males. Differences of this kind between the old and young males may be observed "ith many animals, for instance with birds. It is probable that young male animals have often tended to vaiy in a manner which would not only have Wn of no use to them at an early age, but would have men actually injurious,— as in the acquisition of bright e°lours, which would have rendered them conspicuous 298 THE PRINCIPLES OF Part #• to their enemies, or of structures, such as great horns, which would have expended much vital force in their development. Variations of this kind occurring in the young males will almost certainly have been eliminated through natural selection. With the adult and experienced males, on the other hand, the advan- tage derived from the acquisition of such characters, in their rivalry with other males, will often have more than counterbalanced exposure to some degree of danger. As variations analogous to those which give to the male a superiority over other males in fighting, or in finding, securing, or charming the opposite sex, would, if they happened to arise in the female, be of no service to her, they will not have been preserved through sexual selection in this sex. We have good evidence that with domesticated animals variations of all kinds are soon lost through intercrossing and accidental deaths, it not carefully selected. Consequently, varia- tions of the above kind, if they chanced to arise h1 the female, would be extremely liable to be lost; and the females would he left unmodified, as far as these characters are concerned, excepting in so f»r as they were received through transference from the males. No doubt, if the females varied and trans- mitted their newly acquired characters to their off- spring of both sexes, the characters which were ad- vantageous to the males would be preserved through sexual selection, although they were of no use to the females themselves. In this case, both sexes would be modified in the same manner. But I shall here- after have to recur to these more intricate contin- gencies. Variations occurring late in life, and transmitted to one sex alone, have incessantly been taken advantage Chap. VIII. SEXUAL SELECTION. 299 °f and accumulated through sexual selection in rela- tion to the reproduction of the species ; therefore it appears, at first sight, an unaccountable fact that simi- lar variations have not frequently been accumulated through natural selection, in relation to ordinary habits °f life. If this had occurred, the two sexes would fre- quently have been differently modified, for the sake, h>r instance, of capturing prey or of escaping from danger. "We have already seen and shall hereatter Uieet with other instances of differences of this kind between the two sexes, especially with the lower ani- mals; hut they are rare in the higher classes. We should, however, bear in mind that the sexes in the higher classes generally follow the same habits of life; and supposing that the males alone varied in a manner favouring their power of gaining subsistence, &c., and transmitted such variations to their male offspring alone, these would acquire an organization superior to that of the females ; but it is probable that the females, h'oru having the same general constitution and iroin being exposed to the same conditions, would sooner or later vary in the same manner ; and as soon as this °ccurred, the variations would he equally preserved through natural selection in the two sexes, which would thus ultimately become like each other, lhe case is widely different with variations accumulated through ^xual selection; for the habits of the two sexes in tclation to the reproductive functions are not the same, Hlld sexually-transmitted modifications serviceable to the one sex would in it be preserved, whilst similar ^edifications would often be quite useless to the other 8ex, and consequently would in this latter soon be lost. In the following chapters, I shall treat of the secondary sexual characters in animals of all classes, 300 THE PRINCIPLES OF Part II- and shall endeavour in each case to apply the prim ciples explained in the present chapter. The lowest classes will detain us for a very short time, hut the higher animals, especially birds, must be treated at considerable length. It should be borne in mind that for reasons already assigned, I intend to give only a few illustrative instances of the innumerable structures by the aid of which the male finds the female, or, when iound, holds her. On the other hand, all structures and instincts by which the male conquers other males, and by which he allures or excites the female, will he billy discussed, as these are in many ways the most interesting. Supplement on the proportional numbers of the two sexes in animals belonging to various classes. As no one, as far as I can discover, has paid atten* tion to the relative numbers of the two sexes through' out the animal kingdom, I will here give such materials as I have been able to collect, although they are ex- tremely imperfect. They consist in only a few instances of actual enumeration, and the numbers are not very large. As the proportions are known with certainty o» a large scale in the case of man alone, I will first give them, as a standard of comparison. Man. — Iu England during ten years (from 1857 to 1860) 707,120 children on an annual average have been born alive, in the proportion of 104-5 males to 100 females. But in 1857 the male births through- out England were as 105-2, and in 1865 as 104-0 to 100. Looking to separate districts, in Buckinghamshire (where on an average 5000 children are annually born) C0AP. VIII. SEXUAL SELECTION. 301 the mean proportion of male to female births, during the whole period of the above ten years, was as 102'8 to 100; whilst in N. Wales (where the average annual hirths ’are 12,873) it was as high as 106-2 to 100. 'halving a still smaller district, viz., Rutlandshire (where the annual births average only 739), in 1864 the male hirths were as 114-6, and in 1862 as 97'Q to 100; but oven in this small district the average of the 7385 hirths during the whole ten years was as 104-5 to 100; that is in the same ratio as throughout England.32 The proportions are sometimes slightly disturbed by Unknown causes; thus Prof. Faye states “that m “ some districts of Norway there has been during a “decennial period a steady deficiency of boys, whilst “in others the opposite condition has existed.” In Trance during forty-four years the male to the female hhths have been as 106-2 to 100; but during this Period it has occurred five times in one department, “Hif times in another, that the female biiths have e*ceeded the males. In Russia the average proportion is as hi'di as 108-9 to 100.33 It is a singular fact that "’ith Jews the proportion of male births is decidedly Wger than with Christians : thus in Prussia the propor- tion is as 113, in Breslau as 114, aud in Li vonia as 120 to 100 • the Christian births in these countries being hhe same as usual, for instance, in Livonia as 104 to hJO.'s It is a still more singular fact that m different Nations, under different conditions and climates, in Naples, Prussia, Westphalia, France and England, the T 32 ‘Twenty-ninth Annual Report of the Registrar-General for 186C. ln this report, (p. xii) a special decennial table w given. . * Tor Norway and Russia, see abstract of Rrof. Faye s researches, I? ‘British aud Foreign Medico- CUimrg. Review. April, 1807, p. 3-13, ^ For France, the ‘ Annuaire porn- l’Au 1807, p. -13. 34 In regard to the Jews, see M. Tliury, La Loi de Pr ‘ La Loi de Production des 302 THE PRINCIPLES OF Part I1' excess of male over female births is less when they »re illegitimate than when legitimate.35 In various parts of Europe, according to Prof. F;iVe and other authors, “a still greater preponderance “ males would be met with, if death struck both sex<-s “ in equal proportion in the womb and during birth- “ But the fact is, that for every 100 still-born females* “ we have in several countries from 134-6 to 144'9 “ still-born males.” Moreover during the first four or five years of life more male children die than females; “ for example in England, during the first year, 12$ “ boys die for every 100 girls, — a proportion which i» “ France is still more unfavourable.”36 As a consequent of this excess in the death-rate of male children, and ot the exposure of men when adult to various dangers, and of their tendency to emigrate, the females in all old-settle^ countries, where statistical records have been kept,37 ai‘® found to preponderate considerably over the males. It has often been supposed that the relative age® of the parents determine the sex of the offspring; and Prof. Leuckart38 has advanced what he considers 35 Babbage, 1 Edinburgh Journal of Science,’ 1S29, voL i. p. 88; als® p. 90, ou still-lmrn children. On illegitimate children in England see ‘ Report of Registrar-General for 1866,’ p. xv. 36 ‘British and Foreign Medico-Chi rurg. Review,’ April, 1867, P' 343. Dr. Stark also remarks (‘ Tenth Annual Report of Births, Death3- &c., iu Scotland,’ 1867, p. xxviii) that “ These examples may suffie8 “ to shew that, at almost every stage of life, the males iu Scotia"1* “ have a greater liability to death and a higher death-rate than tla- “ females. The fact, however, of this peculiarity being most strong') “ developed at that infantile period of life when the dress, food, »D‘* “ general treatment of both sexes are alike, seems to prove that t'1*’ “ higher male death-rate is an impressed, natural, and constitution!11 “ peculiarity due to sex alone.” 37 With the savage Guaranys of Paraguay, according to the accui**® Azara (‘Voyages dans l’Ame'rique merid.’ tom. ii. 1809, p. 60, 179)' the women in proportion to the men are as 14 to 13. 3S Leuckart (in Wagner, ‘ Handwdrterhuch der Phys.’ B. iv. s. 774. C»AP. VIII. SEXUAL SELECTION. 303 sufficient evidence, with respect to man and certain domesticated animals, to shew that this is one impor- tant factor in the result. So again the period of impregnation has been thought to be the efficient cause ; but recent observations discountenance this belief. Again, with mankind polygamy has been supposed to lead to the birth of a greater proportion of female infants; but Dr. J. Campbell39 carefully attended to ibis subject in the harems of Siam, and lie concludes that the proportion of male to female births is the Sjtine as from monogamous unions. Hardly any animal has been rendered so highly polygamous as oui imglish hice-horses, and we shall immediately see that their male and female offspring are almost exactly equal in dumber. Horses. — Mr. Tegetmcicr has been so kind as to tabulate for me fr°m the ‘ Racing Calendar’ the births of race-horses during a period of twenty-one years, viz. from 1846 to 1867 ; 1849 being omitted, as no returns were that year published. The total births have been 25, 660,' *“ consisting of 12,763 males and 12,797 females, or in the proportion of 99‘7 males to 100 females. As these numbers are telerably large, and as they are drawn from all parts of England, during several years, we may with much confidence conclude that Mtli 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 are closely like those which °ccur with mankind, when a small and thinly-populated area is con- Adored : thus in 1850 the male horses were as 107T, and m 1807 only 92'6 to 100 females. Jn the tabulated returns the propor- tions vary in cycles, for the males exceeded the females during six Successive years ; and the females exceeded the males during two ^ Anthropological Review, April, 18i0, p- cuii. 40 During the last eleven years a record has been kept of the number of *»es which have proved barren or prematurely slipped their foals; and it deserves notice, as shewing how infertile these highly-nurtured and rather 'hsely-interbred animals have become, that not far from one-third of the “‘Wes failed to produce living foals. Thus during 1866, 809 male colts 816 female colts were born, and 743 mares Exiled to produce offspring. C^i'iug 1867, 836 males and 902 females were born, and 794 mares failed. 304 THE PRINCIPLES OF Part H- periods each of four years : this, however, may he accidental ; least I can detect nothing of the kind with man in the decenniad table in the Registrar's Report for 1866. I may add that certain mares, and this holds good with certain cows and with women, tend to produce more of one sex than of the other ; Mr. Wright of Yeldersley House, informs mo that one of his Arab mares, though put seven times to different horses, produced seven fillies. Dogs. — During a period of twelve years, from 1857 to 1868, tb® births of a large number of greyhounds, throughout England, have been sent to the ‘ Field ’ newspaper ; and T am again indebted to Mr. Tegetmeier for carefully tabulating the results. The recorded births have been 0878, consisting of 3605 males and 3273 female that is, in tlio proportion of HOT males to 100 females. Th® greatest fluctuations occurred in 1864, when the proportion was as 95-3 males, and in 1867, as 11 6-3 males to 100 females. The above average proportion of 110T to 100 is probably nearly correct in th® case of the greyhound, but whether it would hold with other domes- ticated breeds is in some degree doubtful. Mr. Cupples has enquired from several great breeders of dogs, and finds that all without exception believe that females are produced in excess ; he suggests that this belief may have arisen from females being less valued and the consequent disappointment producing a stronger impressiou on the mind. >S keep, i he sexes of sheep arc not ascertained by agriculturist® until several months after birth, at the period when the males ar® castrated; so that the following returns do not give the proportion® 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 on® or two years ; therefore the proportion of males would be somewh®*' greater at birth than at the age of castration. This is a remarkabl® coincidence with what occurs, as we have seen, with mankind, and both cases probably depend on some common cause. 1 have re- ceived returns from four gentlemen in England who have bred lot®' land sheep, chiefly Lcicesters, during the last ten or sixteen year® i they amount altogether to 8965 births, consisting of 4407 mad®3 and 4558 females ; that is in the proportion of 90-7 males to 1(’,) females. With respect to Cheviot and black-faced sheep bred >n Scotland, I have received returns from six breeders, two of them a large scale, chiefly for the years 1867-1869, but some of th® returns extending hack 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 tb® English and Scotch returns together, the total number amount® CHAP. VIII. SEXUAL SELECTION. 305 59,650, consisting of 29,478 males and 30,172 females, or as J7'7 to 100. So that with sheep at the age of castration the females are certainly in excess of the males ; but whether tliis would hold S«od at birth is doubtful, owing to the greater liability in the males to early death.41 Of Cattle 1 have received returns from nine gentlemen of 982 births, too few to bo trusted ; these consisted of 477 bull-calves and ®05 cow-calves ; i.e. in the proportion of 94'4 males to 100 females. Tie Rev. W. 1). Fox informs me that in 1867 out of 34 calves born 011 a farm in Derbyshire only one was a bull. Mr. Harrison Weir ’" rites to me that he has enquired from several breeders of Figs, and taost of them estimate the male to the female births as about 7 to 6. This same gentleman has bred Babbits for many years, ahd has noticed that a far greater number of bucks are produced ^an does. Of mammalia in a state of nature I have been able to learn very mtle. In regard to the common rat, 1 have received conflicting statenients. Mr. II. Elliot of Laighwood, informs rnc that a rat- etcher assured him that he had always found the males in Sreat excess, even with the young in the nest. In consequence this, Mr. Elliot himself subsequently examined some hundred ,1(1 ones, and found the statement true. Mr. F. Buckland has r4 the flocks at this period often consist of hens alone. Mr. Salvin fluid particular attention to the sexes of the humming-birds in bentral America, and he is convinced that with most of the species Jbe males are in excess ; thus one year he procured 204 specimens belonging to ten species, and these consisted of 100 males and of ^ females. With two other species the females were in excess : but the proportions apparently vary either dining different seasons IJr in different localities; for on one occasion the males of Cam- tyloptcrus hemileucurus were to the females as five to two, and "b another occasion48 in exactly the reversed ratio. As bearing on ^bis latter point, 1 may add, that Mr. Powys found in Corfu and hpirus the sexes of the chaffinch keeping apart, and “the females by far the most numerous;” whilst in Palestine Mr. Tristram ((°Und “ the male flocks appearing greatly to exceed the female in dumber.”43 So again with the Quwcalus major, Mr. (1. Taylor™ that in Florida there were “ very few females in proportion to the males,” whilst in Honduras the proportion was the other way, lbe species there having the character of a polygamist. FISH. itli Fish the proportional numbers of the sexes can he ascertained ri,lJy by catching them in the adult or nearly adult state; and there . [ Mr, Jenner Weir dar received similar information, on making enquiries l'mg the following year. To shew the number of chaffinches caught, I "ay mention that in 1869 there was a match between two experts ; and man caught in a day 62, and another 40, male chaffinches. The greatest JJber ever caught by one man in a single day was 70. 'ibis,’ vol. ii. p. 260, as quoted in Gould's ‘ Trochilidse,’ 1861, p. 52. .■ r the foregoing proportions, I am indebted to Mr. Salvin for a table of , results. 49 / T, . lo , „ !s>. *860, p. 137 ; and 1867, p. 369. 308 THE PRINCIPLES OF Part II- are many difficulties in arriving at any just conclusion.61 Infertile females might readily be mistaken for males, as Dr. Gunther has remarked to me in regard to trout. With some species the males are believed to die soon after fertilising the ova. Wilh many species the males 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. Carboimier,62 who has especially attended to the natural history of the pike ( Esox luciu.fi) states that many males, owing to their small size, are devoured by the larger females ; and he believes that the males of almost all fish are exposed from the same, cause to greater danger than the females. Nevertheless in the few cases in which the proportional numbers have been actually observed, the males appear to be largely in excess. Thus Mr. R. Buist, the superintendent of the Stonnontfield experi- ments, says that in 1865, out of 70 salmon first landed for the purpose of obtaining 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 sufficient females 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.”63 This disproportion, no doubt, can be accounted for in part, but whether wholly is very doubtful, by the males ascending the rivers before the females. Mr. F. Bnekland remarks in regard to trout, that “ it is a curious fact that the males prepon- “ derate very largely in number over the females. Tt invariably “ happens that, when the first rush of fish is made to the net, there “ will* be at least seven or eight males to one female found captive- “ L cannot quite account for this ; either the males are more numcr- “ ous than the females, or the latter seek safety by concealment “ rather than flight.” ne then adds, that by carefully searching the banks, sufficient females for obtaining ova can be found.54 Mr. H- Lee informs me that out of 212 trout, taken for this purpose in Lord Portsmouth’s park, 1 50 were males and 62 females. With the Cyprinidai the males likewise seem to be in excess ; but several members of this Family, viz., the carp, tench, bream and minnow, appear regularly to follow the practice, rare in the 51 Leuckart quotes Bloch (Wagner, ‘ Handworterbnch der Phys.’ B- l' ' 1853, s. 775), that with fish there are twice as many males as females. 52 Quoted in the ‘Farmer,’ March 18, 1869, p. 369. 53 ‘The Stormontfieid Piscicultural Experiments,’ 1866, p. 23. The ‘ Field ’ newspaper, June 29th, 1867. 54 ‘ Land and Water,’ 1868, p. 41. Uiup. VIII. SEXUAL SELECTION. 309 '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 males, “ she is immediately pressed closely “ by a male on each side ; and when, they have been, in that situa- tion for a time, are superseded by other two males. 05 INSECTS. In this class, the Lepidoptera alone afford the means of judging °f the proportional numbers of the sexes; for they have been col- lected with special care by many good observers, and have been Wgely 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 find that ibis has ever been done. The general opinion appears to he that the sexes are nearly equal, but in Italy as 1 hear from Professor Canestrini, many breeders are convinced that the females are produced in. excess. The same naturalist, however, informs me, that in the two yearly broods of the Ailanthtis silk- moth {Hornby.i) c.ynthia), 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 observers have been much struck by the apparently enormous preponderance of the males.00 Thus Mr. Bates,67 in speaking of the species, no loss than about a hundred in number, which inhabit the Upper Amazons, says that the males are much more numerous than the females, even in the proportion of a hundred to one. In North America, Edwards, who had great experience, estimates m the Senus Papilio the males to the females as four to one; and Mr. " Tan-ell, ‘Hist. British Fishes,’ vol. i. 1836, p. 307 ; on the Cyprinus lan»o, p. 331 ; on the Tinea vulgaris, p. 331 ; on the Abramis brama, p. w*6. See, for the minnow ( Leuciscus phoxims), ‘ Loudon s Mag. of Nat. fbrt.’ vol. v. 1832, p. 082. 33 Leuckart quotes Meinecke (Wagner, ‘ Handworterbuch der L- >v. 1853, s. 775) that with Butterflies the males are three or four as numerous as the females. i7 ‘The Naturalist on the Amazons,’ vol. ii. 1863, p. 228, 347. Phys.’ times 310 THE PRINCIPLES OF Part II- ^ alsh, who informed me of this statement, says that with P- turnus this is certainly the case, in South Africa, Mr. R. Trimen found the males in excess in 19 species ;58 and in one of these, which swarms in open places, he estimated the number of males as fifty to one female. With another species, in which the males are numerous in certain localities, he collected during seven years only fivo lemales. In the island of Bourbon, M. Maillard states that the males of one species of Papdlio are twenty times as numerous as the females,59 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 in number the males; but this is perhaps the case with three South African species. Mr. Wallace*0 states that the females of Omithoptera crams, in the Malay archipelago, are more common and more easily caught than the males ; but this is a rare butterfly. 1 rnay here add, that in Hyperythra, a genus of moths, Guene'e says, that from four to five females are sent in collections from India for one male. When this subject of the proportional numbers of the sexes of insects was brought before the Entomological Society,61 it was generally admitted that the males of most Lepidoptera, in the adult or imago state, are caught in greater numbers than the females ; hut this lact was attributed by various observers to the more retiring habits of the females, and to the males emerging earlier irom the cocoon, This latter circumstance is well known to occur with most Lepidoptera, as well as with other insects. So that, as M. Bersonnat remarks, the males of the domesticate*- Bmbyx Yamamai, are lost at the beginning of the season, an*1 the females at the end, from the want of mates.® I cannot how- ever persuade myself that these causes suffice to explain the great excess of males in the oases, above given, of butterflies which are extremely common in their native countries. Mr. Stainton, who has paid such close attention during many years to the smaU°r moths, informs me that when lie collected them in the imago state, he thought that the males were ten times as numerous as the females, but that since he has reared them on a large scale from the caterpillar state, he is convinced that the females are the m°st 58 Four of these cases are given by Mr. Trimen in his ‘Ehopalocer8 Africa! Australis.’ a" Quoted by Trimen, * Transact. Ent. Soc.’ vol. v. part iv. 1866, p. 330' 60 ‘ Transact. Liun. Soc.’ vol. xxv. p. 37. 6a ‘Proc. Entomolog. Soc.’ Feb. 17th, 1868. fi" Quoted by Dr. Wallace in ’Proc. Ent. Soc.’ 3rd series, vol. v. 18^’’ p. 487. ’ Chap. VIII. SEXUAL SELECTION. 311 Numerous. Several entomologists concur in tliis view. Mr. Double- day, however, and some others, take an opposite view, and are con- Dnced that they have reared from the egg and caterpillar states a larger proportion of males than ol females. besides the more active habits of the males, their earlier emerg- ence from the cocoon, and their frequenting in some cases more open stations, other causes may be assigned for an apparent or real difference in the proportional numbers oi the sexes ot Lepidop- iera, when captured in the imago state, and when reared from the egg or caterpillar state. It is believed by many breeders in Italy, as I hear from Professor C’anestrini, that the female caterpillar ot 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 caterpillar is larger than the male, and a collector would naturally choose the finest specimens, and thus unintentionally eollsct 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 arc worth the trouble of rearing. Birds when surrounded by caterpillars would probably devour the largest ; and Professor Canestrini informs me that in Italy some brooders believe, though on insufficient evidence, that in the first brood ol the Ailanthus silk-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 anil mois- ture; and thus they would ho exposed during a longer time to danger from ichneumons, birds, &o., and in times of scarcity would perish in greater numbers. Hence it appears quite possible that, in a state of nature, fewer female Lepidoptera may reach maturity than males ; and for our special object we are concerned with the numbers at maturity, when the sexes arc ready to propagate their kind. The manner in which the males of certain moths congregate in extraordinary numbers round a single female, apparently indicates a great excess of males, though this lac-t may perhaps he accounted for by the earlier emergence of the males from their cocoons. Mr. Stainton informs me that from twelve to twenty males may often be seen congregated round a female FAachistw rufocinei ea. it is well known that if a virgin Lasiocampcc qttcrcus or S aturnia cctrpini be exposed in a cage, vast numbers ot males collect round her, and if confined in a room will even come down the chimney to her. 312 THE PRINCIPLES OF Part B- Mr. Doubleday believes that he has seen from fifty to a hundred males of both these species attracted in the course of a single day by a female under confinement. Mr. Trimen exposed in the Isle of Wight a, box in which a female of the Lasiocampa had been confined on the previous day, and five males soon endeavoured to gain admittance. M. Verreaux, in Australia, having placed the female of a small Bombyx in a box in his pocket, was fol- lowed by a crowd of males, so that about 200 entered the house with him.® Mr. Doubleday has called my attention to Dr. Staudinger’s84 list of Lepidoptera, which gives the prices of the males and females of 300 species or well-marked varieties of (Rkopaloeera) butterflies. Ihe prices lor both sexes of the very common species are of course the same ; hut with 114 of the rarer species they differ ; th8 males being in all cases, excepting one, the cheapest. On an ave- rage of the prices of the 113 species, the price of the male to that of the female is as 100 to 140; and this apparently indicates chat inversely the males exceed the females in number in the same proportion. About 2000 species or varieties of moths (Heterocera) are catalogued, those with wingless females being here excluded on account of the difference in habits of the two sexes : of these 2000 species, 141 differ in price according to sex, the males of 130 being cheaper, and the males ot only 11 being dearer than the females. The average price ot the males of the 130 species, to that of the females, is as 100 to 143. With respect to the butterflies in this priced list, Mr. Doubleday thinks (and no man in England has had more experience), that there is nothing in the habits of the species which can account for the difference in the prices of the two sexes, and that it can be accounted for only by an excess in the numbers of the males. But, I am bound to add that Dr. Staudingcr himself, as he informs me, is of a different opinion. He thinks that the less active habits of the lemales and the earlier emergence of the males will account for his collectors securing a larger number of males than ot females, and consequently for the lower prices of the former. With respect to specimens reared from the caterpillar- state, Dr- Staudingcr believes, as previously stated, that a greater number of females than of males die under confinement in the cocoons. He adds that with certain species one sex seems to preponderate over the other during certain years. Oi direct observations on tko sexes of Lepidoptera, roared either Blanchard, ‘ Metamorphoses, Moeurs des Insectes,’ 1868, p. 225-226. ‘ Lcpidopteren-Doubblettren Liste,’ Berlin, No. x. I860. CiUp. VIII. SEXUAL SELECTION. 313 from eggs or caterpillars, I have received only the few following cases : — Rev. J. Hollins 63 of Exeter reared, during 1868, . imagos of 73 species, which consisted ot *'h\ Albert Jones of Eltham reared, during 1868, im- ages of 9 species, which consisted of during 1869 he reared imagos from 4 species, consist- , ing of . . . . *'*r. Buckler of Emsworth, Hants, during 1869, reared . imagos from 74 species, consisting of . . . . Dl'. Wallace of Colchester reared from one brood of . Bombvx Cynthia IJr- Wallace raised, from cocoons ofBombyx Pernyi sent n from China, during 1869 Ur. Wallace raised, during 1868 and 1869, from two lots of cocoons of Bombyx yama-mai . . . , . . Total Males. Females. 153 137 159 126 114 112 180 169 52 48 224 123 52 46 934 761 So that in these eight lots of cocoons and eggs, males were pro- ceed in excess. Taken together the proportion of males is as ■^2'7 to 100 females. But the numbers are hardly large enough 4(1 be trustworthy. On the whole, from the above various sources of evidence, all feinting to the same direction, I infer that with most species of bepidopttra, the males in the imago state generally exceed the ett)ales in number, whatever the proportions may be at their first emergence from the egg. With reference to the other Orders of insects, 1 have been able ,0 collect very little reliable information. With the stag-beetle facanus cervus) “ the males appear to he much more numerous ‘than the females” but when, as Cornelius remarked during 1867, Unusual number of these beetles appeared in one part of Ger- ?auy, the females appeared to exceed the nudes as six so one. With one of the Elatoricto, the males are said to he much more Numerous than the females, and “ two or three are often found Suited with one female f* so that here polyandry seems to prevail. This naturalist lias been so kind as to send ine some results from 'finer years, in which the females seemed to preponderate ; but so many the figures were estimates, that 1 found it impossible to tabulate them. e GUnther’s ‘Record of Zoological Literature,’ 1867, p. 260. On the pwess of female Lucanus, ibid. p. 250. On the males of Lucanus in Eng- j! Westwood, ‘ Modern Class, of Insects,’ vol. i.lp. 187. On the Siagoninm, 01cl- p. 172. 314 THE PRINCIPLES OF Part H With Siagonium (Staphylinidaj), in which the males are furnished with horns, “ the females are far more numerous than the opposite “ sex.” Mr. Janson stated at the Entomological Society that the females of the hark-feeding Tomicus villosus are so common as t*3 he a plague, whilst the males are so rare as to be hardly know3- In other Orders, from unknown causes, but apparently in some inf stances owing to parthenogenesis, the males of certain species have never been discovered or are excessively rare, as with several of tbc Cynipid®.67 In all the gall-making Cynipidaj known to Mr. Wahhi the females are four or five times as numerous as the males ; and it is, as he informs me, with the gall-making Cecidomyikn (Dipterft)- With some common species of Saw-flies (Tenthredina) Mr. Smith has reared hundreds of specimens from larva of all siM6' l)ut has never reared a single male : on the other hand Curtis say& that with certain species (Athalia), bred by him, the males to tl'e females were as six to one ; whilst exactly the reverse occurred wi^ the mature insects of the same species caught in the fields. Wi^ the Neuroptera, Mr. Walsh states that iu many, but by no mean9 in all, the species of the Olonatous groups (Ephemerina), there is* great overplus of males : in the genus Hctierina, also, the males ar® generally at least four times as numerous as the females. In certain species in the germs Complies the males are equally numerous whilst in two other species, the females are twice or thrice numerous as the males. In some European species of Psocus tbo®” sands of females may bo collected without a single male, whilst with other species of the same genus both sexes are common.69 I* England, Mr. Mac Lachlan has captured hundreds of the feioak Apatania muliebris, but has never seen the male; and of J3ore“s hyemalis only four or five males have been here seen.70 With mo®1 of these species (excepting, as I have heard, with the Tenthredin:1') there is no reason to suppose that the females are subject to parthr nogenesis ; and thus we sec how ignorant wc are on the causes of ^ apparent discrepancy in the proportional numbers of the two scs1*; in the other Classes of the Articulata 1 have been able to coll1** still less information. With Spiders, Mr. Blackwall, who has cab' fully attended to this class during many years, writes to me tfc®1 the males from their more erratic habits are more commonly seeIJ’ 67 Walsh, in ‘ The American Entomologist,’ vol. i. 1869, p. 103. F. ‘ Record of Zoological Literature,’ 1867, p. 328. 88 ‘ Farm Insects,’ p. 45-46. 69 ‘ Observations on N. American Neuroptera,’ by H. Hao-en and B. Walsh, ‘ Proc. Ent. Soc. Philadelphia,’ Oct. 1863, p. 168, 223, 239. 70 ‘ Proc. Ent. Soc. London,’ Feb. 17, 1868. C«AP. VIII. SEXUAL SELECTION. 315 and therefore appear to be the more numerous. This is actually the case with a few species ; but he mentions several species in six Sonera, in which the females appear to bo much more numerous than the males.71 The small size of the males in comparison with die females, which is sometimes carried to an extreme degree, and 'heir widely different appearance, may account in some instances f°r their rarity in collections.72 Some of the lower Crustaceans are able to propagate their kind Sexually, and this will account for the extreme rarity of the males. With some other forms (as with Tanais and Cypris) there is reason *0 believe, as Fritz Muller informs me, that the male is much shortcr- Wd than the female, which, supposing the two sexes to be at first equal in number, would explain the scarcity of the males. On the other hand this same naturalist has invariably taken, oil the shores of Brazil, far more males than females of the Diastylidie and of °ypridina; thus with a species in the latter genus, (53 specimens Ca'tght the same day, iucluded 57 males ; but he suggests that this Preponderance may be due to some unknown difference in the habits r,f the two sexes. With one of the higher Brazilian oralis, namely a Gelasimus, Fritz Miillcr found the males to be more numerous d*aa the females. The reverse seems to be the case, according to large experience of Mr. C. Spence Bate, with six common British Ctobs, the names of which he has given me. On the Power of Natural Selection to regulate the pro- motional Numbers of the Sexes, and General Fertility. — Iff some peculiar cases, an excess in the number of one Sex over the other might be a great advantage to a species, as with the sterile females of social insects, or "ith those auimals in which more than one male is ’e<]uisite to fertilise the female, as with certain cirri- Pedes and perhaps certain fishes. An inequality be- tween the sexes in these cases might have been acquired through natural selection, but from their rarity they **eed not here be further considered. In all ordinary j, ,l Another great authority in this class, Prof. Tliorell ofUpsala (‘On European Spiders,’ 1809-70, part i. p- 205) speaks as if female spiders were generally commoner than the males. > See, on this subject, Mr. Pickard-Cainbridge, as quoted in 1 Quarterly °Urnal of Science,’ 1868, p. 429. 316 THE PRINCIPLES OP Part cases an inequality would be no advantage or disa«' vantage to certain individuals more than to others; and therefore it could hardly have resulted from natural selection. We must attribute the inequality to tke direct action of those unknown conditions, which wit*1 mankind lead to the males being born in a somewhat larger excess in certain countries than in others, °r which cause the proportion between the sexes to di&eI slightly in legitimate and illegitimate births. Let us now take the case of a species producing fro#1 the unknown causes just alluded to, an excess of on1' sex — we will say of males — these being superfluous useless, or nearly useless. Could the sexes be equalised through natural selection ? We may feel sure, from characters being variable, that certain pairs would pi0, duce a somewhat less excess of males over females tha» other pairs. The former, supposing the actual numher of the offspring to remain constant, would necessarily produce more females, and would therefore be more pi®" ductive. On the doctrine of chances a greater numW of the offspring ot the more productive pairs would su1' vivo ; and these would inherit a tendency to procrea*® fewer males and more females. Thus a tendency t0" wards the equalisation of the sexes would he brougO about. But our supposed species would by this proces* be rendered, as just remarked, more productive; an1* this would in many cases be far from an advantage* for whenever the limit to the numbers which exist, <1®' peuds, not on destruction by enemies, but on the atnoU1^ of tood, increased fertility will lead to severer comp®*1" tion and to most of the survivors being badly fed. I11 this case, if the sexes were equalised by an increase & the number of the females, a simultaneous decrease i11 the total number of the offspring would be beneficial > and this, I believe, could be effected through natura C«4P. VJII. SEXUAL SELECTION. 317 Section in the manner hereafter to be described. The SatQe train of reasoning is applicable in the above, as well as in the following case, if we assume that females instead of males are produced in excess, for 8ring from the less fertile parents would have no Effect advantage over the offspring from the more fer- tile parents, when all were mingled together in the district. All the individuals would mutually tend P' starve each other. The offspring indeed of the less |®rtile parents would lie under one great disadvantage, f°1' from the simple fact of being produced in smaller ’(Umbers, they would be the most liable to extermina- tion. Indirectly, however, they would partake of one §reat advantage ; for under the supposed condition of Severe competition, when all ivere pressed for food, it is ^treinely probable that those individuals which from ^'Uie variation in their constitution produced fewer eggs 320 THE PRINCIPLES OF SEXUAL SELECTION. PAET H or young, would produce them of greater size or vigour; and the adults reared from such eggs or young would manifestly have the best chance of surviving, and would inherit a tendency towards lessened fertility- The parents, moreover, which had to nourish or provide for fewer offspring would themselves be exposed to » less severe strain in the struggle for existence, and would have a better chance of surviving. By tliesu steps, and by no others as far as I can see, natural selection under the above conditions of severe coni' petition for food, would lead to the formation of a lie" race less fertile, but better adapted for survival, than the parent-race. C>UP. IX. SEXUAL SELECTION. 321 CHAPTER IX. Secondary Sexual Characters in the Lower Classes of the Animal Kingdom. Hose characters absent in the lowest classes i'rillifiut colours Mollusca — Annelids — Crustacea, secondary sexual characters strongly developed ; dimorphism ; colour; chaiacters not acquired before maturity — Spiders, sexual colours of; stridulation by the males — Myriapoda. ^ the lowest classes the two sexes are not rarely united in the same individual, and therefore secondary sexual characters cannot he developed. In many cases in which die two 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 hiuch too low mental powers to feel mutual rivalry, °r to appreciate each other’s beauty or other attrac- tions. Hence in these classes or sub-bin gdoms, such as the •Protozoa, Ocelenterata, Echinodermata, Scolecida, true secondary sexual characters do not occur ; and this fact agrees with the belief that such characters in the higher classes have been acquired through sexual selec- tion, which depends on the will, desires, and choice ot either sex. Nevertheless some few apparent exceptions °ccur; thus, as I bear from Dr. Baird, the males of certain Eutozoa, or internal parasitic worms, differ slightly in colour from the females ; hut we have no reason to suppose that such differences have been augmented through sexual selection. VOL. i. Y 322 SEXUAL SELECTION. Part II. Many of the lower animals, whether hermaphrodites or with the sexes separate, are ornamented with the most brilliant tints, or are shaded and striped in an elegant manner. This is the case with many coral-' and sea-anemonies ( Actiniae), with some jelly-fish (Me- dusae, Porpita, &c.), with some Planarke, Ascidians, numerous Star-fishes, Echini, &c. ; but we may conclude from the reasons already indicated, namely the union of the two sexes in some of these animals, the per- manently 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. With the higher animals the case is very different ; for with them when one sex is much more brilliantly or conspicuously coloured than the other, and there is no difference in the habits of the two sexes which will account for this difference, we have reason to believe in the influence of sexual selection ; and this belief is strongly con- firmed when the more ornamented individuals, which are almost always the males, display their attractions before the other sex. We may also extend this con- clusion 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 °r even gorgeous colours of many animals in the lowest classes ? It appears very doubtful whether such colours usually serve as a protection ; but we are extremely liable to err in regard to characters of all kinds i,J relation to protection, as will be admitted by every one who has read Mr. Wallace’s excellent essay on tbis subject. It would not, for instance, at first occur t° any ons that the perfect transparency of the Medus®> or jelly-fishes, was of the highest service to them as *a Ohap. IX. SEXUAL SELECTION. 323 protection ; but when we are reminded by Hackel that not only the medusae but many floating mollusca, crus- taceans, and even small oceanic fishes partake of this same glass-like structure, we can hardly doubt that they thus escape the notice of pelagic birds and other enemies. Notwithstanding our ignorance how far colour in many cases serves as a protection, the most probable view in regard to the splendid tints ot many of the lowest animals seems to be that their colours aie the direct result either of the chemical nature oi 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 pur- pose. So again with many animals, especially the lower ones, the bile is richly coloured ; thus the extreme beauty of the Eolidm (naked sea-slugs) is chiefly due, as I am informed by Mr. Hancock, to the biliary glands 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 sup- poses 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 being thus gained, in the complex laboratory of living organisms. 324 SEXUAL SELECTION. Part II. The sub-lcingdom of the Moll'usca. — Throughout this great division (taken in its largest acceptation) of the animal kingdom, secondary sexual characters, such as we are here considering, never, as far as I can discover, occur. Nor could they be expected in the three lowest classes, namely in the Aseidians, Polyzon, and Brachio- pods (constituting the Molluscoida of Huxley), 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, hermaphro ditism is not rare. In the next higher class of the Gasteropoda, or univalve shells, the sexes are either united or separate. But in this latter case the males never possess special organs for finding, securing, or charming the females, or for fighting with other males. The sole external difference between the sexes consists, as I am informed by Mr. Gwyn Jeffrevs, in the shell sometimes differing a little" in form ; ' for instance, the shell of the male periwinkle ( Littorin ® littore'a ) 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 eu- dowed with sufficient mental powers for the members of the same sex to struggle together in rivalry, and thus to acquire secondary sexual characters. Never- theless 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,1 “Qui- “ conque a eu 1 occasion d’observer les amours des lima- 1 * De l’Esptce et de la Class.’ &c., 1869, p. 106. C«AP. IX. MOLLUSCS. 325 “ Qons, ne saurait mettre en doute la seduction deployee “dans les mouvements et les allures qui preparent et “ accomplissent le double einbrasseinent de ces ber- “ maphrodites.” These animals appear also susceptible °f some degree of permanent attachment: an accurate observer, Mr. Lonsdale, informs me that lie placed a Pair of land-shells ( Helix pomatia), one of which was "'Giddy, into a small and ill-provided garden. After a sbort, 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 same track and disap- peared over the wall. Even in the highest class of the Mollusca, namely the Cephalopoda or cuttle-fishes, in which the sexes are Separate, secondary sexual characters of the kind which Vve are here considering, do not, as far as I can discover, 0ccur. This is a surprising circumstance, as these afomals possess highly-developed sense-organs and have e°nsiderable mental powers, as will be admitted by "Very one who has watched their artful endeavours to escape from an enemy.2 Certain Cephalopoda, however, ai'6 characterised by one extraordinary sexual character, hatnely, that the male element collects within one of foe arms or tentacles, which is then cast off, and, Ringing by its sucking-discs to the female, lives for a ^me 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 T>^e6, ^OT distance, the account wliich I have given in my 1 Journal Researches,’ 1845, p. 7. 326 SEXUAL SELECTION. Pakt II- of Hectocotyle. But this marvellous structure may he classed as a primary rather than as a secondary sexual character. Although with the Mollusea sexual selection does not seem to have come into play ; yet many univalve and bivalve shells, such as volutes, cones, scallops, &c., ate beautifully 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 o» growth. The amount of light seems to a certain extent to be influential; 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 and the parts covered by the mantle less highly coloured than the upper and exposed surfaces.3 In some cases, as with shells living amongst corals or brightly-tinted sea-weeds, the bright colon1'3 may serve as a protection. But many of the nudibrand1 mollusea, or sea-slugs, are as beautifully coloured llS any shells, as may be seen in Messrs. Aider and Ha"' cock’s magnificent work ; and from information kindly given me by Mr. Hancock, it is extremely doubt!'1 whether these colours usually serve as a protection With some species this may be the case, as with °D® which lives on the green leaves of algae, and is itse' bright-green. But many brightly-coloured, white t,r otherwise conspicuous species, do not seek concealment whilst again some equally conspicuous species, as we'd as other dull-coloured kinds, live under stones and 1,1 3 I have given (‘Geolog. Observations on Volcanic Islands,’ 18 p. 53) a curious instance of the influence of light on the colours ^ a frondescent incrustation, deposited by the surf on the const-rocls Ascension, and formed by the solution of triturated sea-she-lls. Chap. IX. MOLLUSCS AND ANNELIDS. 327 dark recesses. So that with these nudibranch molluscs, colour apparently does not stand in any close relation to the nature of the places which they inhabit. These naked sea-slug3 are hermaphrodites, yet they pair together, as do laud-snails, many of which have extremely pretty shells. It is conceivable that two hermaphrodites, attracted by each others greater beauty, might unite and leave offspring which would inherit their parents’ greater beauty. l>ut 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, so as to increase in numbers, over the offspring of the° less beautiful, unless indeed vigour and beauty generally coincided. We have not here a number ot males becoming mature before the females, and the more beautiful ones selected by the more vigorous females. If, indeed, brilliant colours ivere beneficial to an 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- loorms). — In this class, although the sexes (when separate) sometimes differ from each other in characters ol 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 attributed to sexual selection. These animals, like those in the pre- ceding classes, apparently stand too low in the scale, f,m the individuals of either sex to exert any choice in selecting a partner, or for the individuals of the same Slx to struggle together in rivalry. 32S SEXUAL SELECTION. Part It Sub-kingdom of the Arthropoda : Class, Crustacea. — In this great class we first meet with undoubted se- condary sexual characters, often developed in a remark' able manner. Unfortunately the habits of crustaceans are very imperfectly known, and we cannot explain the uses of many structures peculiar to one sex. With the lower parasitic species the males are of small size, nd they alone are furnished with perfect swimming- legs, antennoe and sense-organs ; the females being destitute of these organs, with their bodies often consist- ing 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 consequently do not concern us. In various crustaceans, belonging to distinct families, the anterior antennae are furnished with peculiar thread-like bodies, which are believed to act as smelling-organs, and these are much more nume- rous 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 smell- ing-threads has probably been acquired through sexual selection, by the better provided males having been the most successful in finding partners and in leaving off- spring. Fritz Muller has described a remarkable dimor- phic species of Tanais, in which the male is represented by two distinct forms, never graduating 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 cheke or pincers which serve to hold the female. Fritz Muller sumresF that these differences between the two male forms of the same species must have originated in certain individuals having varied in the number of the smelling-threads, whilst other individuals varied in the shape and size of C»AI>, IX. CRUSTACEANS. 329 their diel® ; so that of the former, those which were best able to find the female, and of the latter, those which were test able to hold her when found, have left the greater number of progeny to inherit their respec- tive advantages.4 In some of the lower crusta- ceans, the right-hand anterior a*>tenna of the male differs greatly in structure from the left-hand one, the latter re- sembling in its simple tapering joints the antennae of the fe- male. In the male the modi- fied antenna is either swollen in the middle or angularly bent, °r converted (tig. 3) into an degant, and sometimes wonder- fully complex, prehensile organ.5 If serves, as I hear from Sir J. Lubbock, to hold the female, aud for this same purpose one °f the two posterior legs (b) ou the same side of the body is converted into a forceps. In aUother family the inferior or posterior antennae are “ curiously zigzagged in the ^ules alone. 4 ‘ Facts and Arguments for Darwin,’ English Iranslat. 1869, p. 20. the previous discussion on the olfactory threads. Sara has de- bribed a somewhat analogous case (as quoted in ‘Nature, 18/0, It 455) in a Norwegian crustacean, the Pontoporcia affinis. 5 See Sir J. Lubbock in ‘Annals, and Mag. of Nat. Hist.’ vol. xi. J853, pi. i. aild x. ; and vol. xii. (1853) pi. vii. _ See also Lubbock in transact. Ent. Soc.’ vol. iv. new series, 18oG-1858, p. 8. "W itli respect ^ tlie zigzagged antennse mentioned below, see Fritz Muller, ‘Facts and Arguments for Darwin ’ 1869, p. 40, foot-note. a Fig. 3. Labidocera Darwini! (from Lubbock). a. Part of rigbt-band anterior an- tenna of male, forming a pre- hensile organ. b. Posterior pair of thoracic legs of male. c. Ditto of female. SEXUAL SELECTION. Pari' II In the higher crustaceans the anterior legs form a pair of chelae or pincers, and these are generally larger in the male than in the female. In many species the chelae on the opposite sides of the body are of unequal size, tie right-hand one being, as I am iu" UR— The artist by mistake hus reversed the drawing, and made the left-hand chr|11 thp largest. Hg. 5. Second leg of male Orchestiu Tucuratinga (from Fritz Muller). Fig. 6. Ditto of female. formed by Mr. 0. Spence Bate, generally, though invariably, the largest. This inequality is often much greater in the male than in the female. The two chehe also often differ in structure (figs. 4 and 5, b'), the small®1' one resembling that of the female. What advantage Chap. IX. CRUSTACEANS. 331 is gained by their inequality in size on the opposite sides of the body, and by the inequality being much greater in the male than in the female ; and why, when they are of equal size, both are often much larger in the male than in the female, is not known. The ckelte are sometimes of such length and size that they cannot possibly be used, as I hear from Mr. Spence Bate, for carrying food to the mouth. In the males of certain fresh- water prawns (Pakemon) the right leg is actually longer than the whole bo: ly.6 It is probable that the great size of one leg with its chela: may aid the male in fighting with his rivals; but this use will not account for their inequality in the female on the opposite sides of the body. In Gelasimus, according to a statement quoted by Milne- Edwards,7 the male and female live in the same burrow, which is worth notice, as shewing that they pair, and the male closes the mouth of the burrow with one of its oh el to, which is enormously developed ; so that here it indirectly serves as a means of defence. Their main Use, however, probably is to seize and to secure the female, and this in some instances, as with Gammarus, is known to be the ease. The sexes, however, of the common shore-crab ( Garcinus mamas), as Mr. Spence Bate informs me, unite directly after the female has Moulted her hard shell, and 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 previously to the act of moulting, she could then be seized with impunity. _ Fritz Muller states that certain species of Melita are 8 See a paper by Mr. 0. Spence Bate, with figures, in ‘Proe. Zoolog. Soc.’ 1S68 o 363' and on the nomenclature of tlie genus, ibid. p. 080. I am greatly indebted to Mr. Spence Bate for nearly all the above statements with respect to the clielee of the higher crustaceans. 7 ‘ Hist. Nat. des Crust.’ tom. ii. 1837, p. 50. 332 SEXUAL SELECTIOX. Part II- distinguished from all other amphipods by the females having “the coxal lamellae of the penultimate pair of “ produced into hook-like processes, of which the “ males lay hold with the hands of the first pair.” The development of these hook-like processes probably resulted from those females which were the most securely held during tire act of reproduction, having left the largest number of offspring. Another Bra- zilian ampldpod ( Orchestia DarwinU, fig. 7) is de- scribed by Fritz Muller, as presenting a case of dimor- phism, like that of Tanais; for there are two male forms, which differ in the structure of their cliche.8 As chelte of either shape would certainly have sufficed to hold tlio female, for both arc 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 advan- tages, from their differently shaped organs. It, is not known that male crustaceans fight together for the possession of the females, but this is probable ; lot with most animals when the male is larger than the female, ho seems to have acquired his greater size by having conquered during many generations other males. Now Mr. Spence Bate informs me that in most of the crustacean 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 ol the Entomostraca must be excepted. The chelas of many crustaceans are weapons well adapted for fighting. Thus a Devil-crab (Portunus puber) was seen by a sou of Mr. Bate fighting wdh a Carcinus mamas, and the latter was soon thrown on its back, and had every limb torn from its body- 8 Fritz II filler, ‘Facts and Arguments for Darwin,’ 1869, p. 25-28. C>Up. IX. CRUSTACEANS. 333 ^hen several males of a Brazilian Gelasimus, a species j^rnished with immense pincers, were placed together |Jy Fritz Muller in a glass vessel, they mutilated and billed each other. Mr. Bate put a large male Carcinus P\ e* 7- Orchestia Darwinll (from Fritz Mttller), showing the differently-constructed cliche of the two mule forms. n,bna& into a pan of water, inhabited by a female paired jVhh a smaller male ; the latter was soon dispossessed, Ut> as Mr. Bate adds, “ if they fought, the victory 334 SEXUAL SELECTION. Paet II- “ was a bloodless one, for I saw no wounds.” This same naturalist separated a male sand-skipper (so coin' mon on our sea-shores), Gammarus marinus, from its female, both of which were imprisoned in the satD® vessel with many individuals of the same species. Th® female being thus divorced joined her comrades. Aft®r an interval the male was again put into the sam® vessel and he then, after swimming about for a time* dashed into the crowd, and without any fighting at one® took away his wife. This fact shews that in the AmphJ' poda, an order low in the scale, the males and femaleS recognise each other, and are mutually attached. The mental powers of the Crustacea are probably higher than might have been expected. Any one w h° has tried to catch one of the shore-crabs, so numero«s on many tropical coasts, will have perceived how war?' and alert they are. There is a large crab (Bir03 latro), found on coral islands, which makes at th® bottom of a deep burrow a thick bed of the pick®® fibres of the cocoa-nut. It feeds on the fallen fruit ot" this tree by tearing off the husk, fibre by fibre; it always begins at that end where the three cy®' like depressions are situated. It then breaks through one of these eyes by hammering with its heavy fro®1 pincers, and turning round, extracts the albumin®’15 core with its narrow posterior pincers. But these actio®6 are probably instinctive, so that they would be p®1 formed as well by a young as by an old anin®1 * The following case, however, can hardly be so c®11 sidered : a trustworthy naturalist, Mr. Gardner,9 whus watching a shore-crab (Gelasimus) making its burro*’ • ‘Travels in the Interior of Brazil,’ 1846, p. 111. I have g-iven,^^ my ‘ Journal of Besearches,’ p. 463, an account of the habits of Birgos. CRUSTACEANS. 335 CiUt>. IX. threw some shells towards the hole. One rolled in, a“d three other shells remained within a few inches of the mouth. In about live minutes the crab brought the shell which had fallen in, and carried it away t° the distance of a foot; it then saw the three other shel]g lying near, and evidently thinking that they '^ight likewise roll in, carried them to the spot where 't had laid the first. It would, I think, be difficult to distinguish this act from one performed by man by the ai(l of reason. With respect to colour which so often differs in the Wo sexes of animals belonging to the higher classes, Spence Bate does not know of any well-marked '“stances with our British crustaceans. In some cases, lowever, the male and female differ slightly in tint, (“t Mr. Bate thinks not more than may be accounted by their different habits of life, such as by the '“ale wandering more about and being thus more ex- ited to the light. In a curious Bornean crab, which '“habits sponges, Mr. Bate could always distinguish the s“Xcs by the male uot having the epidermis so much bibbed off. Dr. Power tried to distinguish by colour sexes of the species which inhabit the Mauritius, but “Ways failed, except with one species of Squilla, pro- Jably the S. stylifera, the male of which is described as >oing «0f a beautiful blueish-green,” with some of the appendages cherry-red, whilst the female is clouded Wli brown and grey, “with the red about her much less vivid than in the male.”10 In this case, we may s“spect the agency of sexual selection. With Sa- P“ifina (an oceanic genus of Eutomostraca, and tliere- °re low in the scale) the males are furnished with k Mr. Mr. Ch. Eraser, in ‘Proc. Zoolog. Soc.’ 1869, p. I • Bate for the statement from Dr. Power. I am indebted 336 SEXUAL SELECTION. Part H- minute shields or cell-like bodies, which exhibit beaU' tiful changing colours ; these being absent in the females, and in the case of one species in both sexes. It would, however, be extremely rash to conclude that these curious organs serve merely to attract the females- In the female of a Brazilian species of Gela-simus, the whole body, as I am informed by Fritz Muller, is of fl 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 t° change in the course of a few minutes— the whit0 becoming dirty grey or even black, the green “losing much of its brilliancy.” The males apparently a*0 much more numerous than the females. It deserve* especial notice that they do not acquire their bright colours until they become mature. They differ a'*0 from the females in the larger size of their cheh0- In some species of the genus, probably in all, th0 sexes pair and inhabit the same burrow. They ar0 also, as we have seen, highly intelligent animate' From these various considerations it seems higb^ probable that the male in this species has becon,e gaily ornamented in order to attract or excite tl'e female. It has just been stated that the male Gelasimus doe* not acquire his conspicuous colours until mature olH nearly ready to breed. This seems the general rule 10 the whole class with the many remarkable difference’" in structure between the two sexes. We shall he>’^ after find the same law prevailing throughout the g1^ sub-kingdom of the Vertebrata, and in all cases it 9 eminently distinctive of characters which have bet'11 11 Claus, 1 Die freilebenden Copepoden,’ 1S63, s. 35. C«AP. IX. SPIDEKS. 337 acquired through sexual selection. Fritz Muller12 gives Some striking instances of this law; thus the male sand-hopper (Orchestia) does not acquire his large claspers, which are very differently constructed from those of the female, until nearly full-grown; whilst young his claspers resemble those of the female. Thus, again, the male Brachyscelus possesses, like all other ainphipods, a pair of posterior antennas ; the female, and this is a most extraordinary circumstance, is desti- tute of them, and so is the male as long as he remains ^nmature. Class, Arachnida (Spiders).— The males are often darker, hut sometimes lighter than the females, as may he seen in Mr. Blackwall’s magnificent work.13 In some species the sexes differ conspicuously from each °ther in colour ; thus the female of Sparassus sma- Ta!/dulus is dullish-green ; whilst the adult male has the abdomen of a fine yellow, with three longitudinal Bi'ipes of rich red. In some species of Tliomisus the hvo sexes closely resemble each other ; in others they differ much; thus in T. citreus the legs and body of the female are pale-yellow or green, whilst the front legs of the male are reddish-brown: in T. floricolens, the legs of the female are pale-green, those of the ^ale being riuged in a conspicuous manner with various tints. Numerous analogous cases could be given in the genera Epeira, Nephila, Pbilodromus, Theridion, Liny- pliia, &c. 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. Elackwall 12 ‘ Facts and Arguments,’ &c., p. 79. 13 ‘ A History of the Spiders of Great Britain,’ 1861-G4. For the blowing facts, see p. 102, 77, 88. VOL. I. 2 338 SEXUAL SELECTION. Pabt II- thinks that, as a general rule, it is the male. Both sexes whilst young, as I am informed by the same author, usually resemble each other ; and both often undergo great 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-mentioned brightly-coloured Spn* rassus at first resembles the female and acquires biS peculiar tints only when nearly adult. Spiders ate possessed of acute senses, and exhibit much intelb' gence. The females often shew, as is well known, the strongest affection for their eggs, which they carry about enveloped in a silken web. On the whole ’t appears probable that well-marked differences in colon1' between the sexes have generally resulted from sexual selection, either on the male or female side. But doubts may be entertained on this head from the extreffl0 variability in colour of some species, for instance of Theridion lineatum, the sexes of which differ when adult ; this great variability indicates that their colours have not been subjected to any form of selection. Mr. Blackwall does not remember to have seen th0 males of any species fighting together for the posses' sion of the female. Nor, judging from analogy, is tin- probable ; for the males are generally much smaHel than the females, sometimes to an extraordinary do' gree.14 Had the males been in the habit of fightiu- together, they would, it is probable, have graduallj 14 Aug. Vinson (‘Arane'ides des Ilea de la Reunion,’ pi. vi. fig3-, and 2) gives a good instance of the small size of the male in 2 Vpei nigra. In this species, as I may add, the male is testaceous and 4 female black with legs banded with red. Other even more strik>De cases of inequality in size between the sexes have been recon (‘ Quarterly Journal of Science,’ 1868, July, p. 429); but I have not see the original accounts. Char -lx. SPIDERS AND MYRIAPODA. 339 acquired greater size and strength. Mr. Blackwall has sometimes seen two or more males on the same web With a single female ; hut their courtship is too tedious and prolonged an affair to be easily observed. The male 's extremely cautious in making his advances, as the female carries her coyness to a dangerous pitch. De Geer saw a male that ,ciii 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.” 15 Westring has made the interesting discovery that the males of several species of Theridion1® have the power of making a stridulating sound (like that made by many beetles and other insects, but feebler), whilst the females are quite mute. The apparatus consists of a serrated ridge at the base of the abdomen, against which the hard hinder part of the thorax is rubbed ; and of this structure not a trace could be detected in the females. From the analogy of the Orthoptera and Homoptera, to be described in the next chapter, we may feel almost sure that the stridulation serves, as Westring remarks, either to call or to excite the female ; °and this is the first case in the ascending scale of the animal kingdom, known to me, of sounds emitted for this purpose. Class, Myriapoda— In neither of the two orders in this class, including the millipedes and centipedes, 15 Kirby and Spence, ‘ Introduction to Entomology,’ vol. i. 1818, P. 280. 16 Tlieridion (Asageaa, Sund.) serratipes, 4-punctatum et guttatum; See Westring, in Kroyer, ‘ Naturhist. Tidskrift,’ vol. iv. 1842-1843, P- 349 ; and vol. ii. 1846-1849, p. 342. See, also, for other species, Aranese Svecic®,’ p. 184. z 2 340 SEXUAL SELECTION. Part II- can I find any well-marked instances of sexual dif- ferences such as more particularly concern us. In Glomeris Imibata, however, and perhaps in some fen 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 be- longing to one of the anterior segments of the body, or to the posterior segment, are modified into prehensile 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. It is a much more unusual circumstance, as we shall see when we treat of Insects, that it is the female in Lithobius which is furnished with prehensile appen- dages at the extremity of the body for holding the male. 17 11 Walckenaer et P. Gervais, ‘Hist. Nat. des Insectes : Apt'eres, torn. iv. 1S47, p. 17, 19, GS. Chap. X. SEXUAL SELECTION. 341 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 lliysanura — Diptera Hemiptera — Homoptera, musical Dowers possessed by the males alone — Orthoptora, musical instruments of the males, much diversified in structure; pugnacity; colours — Neuroptera, sexual differences in colour — Hymenoptera, pugnacity and colours — Coleoptera, colours ; furnished with great horns, apparently as an ornament ; battles ; stridulating organs generally common to both sexes. Iff the immense class of insects the sexes sometimes differ in their organs for locomotion, and often in tlieir sense-organs, as in the pectinated and beauti- fully plumose antennae of the males of many species, hi one of the Ephemerae, namely Chloeon, the male has great pillared eyes, of which the female is entirely destitute.1 The ocelli are absent in the females of certain other insects, as in the Mutillidce, which are likewise destitute of wings. But we are chiefly con- cerned with structures by which one male is enabled to Ampler another, either in battle or courtship, through |us strength, pugnacity, ornaments, or music. The innumerable contrivances, therefore, by which the male ':s able to seize the female, may be briefly passed over, besides the complex structures at the apex ol the abdo- men, which ought perhaps to be ranked as primary ’ Sir J. Lubbock, ‘ Transact. Linnean Soc.’ vol. xxv. 1866, p. 484 respect to tlie Mutillidae see Westwood, ‘ Modem Class, of Insects,’ Vo1- ii. p. 213. 342 SEXUAL SELECTION. Part II. organs,2 “it is astonishing,” as Mr. B. I). Walsli3 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 sometimes used for this purpose ; thus the male Corydalis eornuius (a ueuropterous insect in some degree allied to the Dragon flies, &c.) has im- mense curved jaws, many times longer than those of the female ; and they are smooth instead of being toothed, by which means he is enabled to seize her without injury.'’ One of the stag-beetles of North America (Lucanus elaphus ) 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 (Arnrnoph'ila) the jaws in the two sexes are closely alike, but are used for widely different purposes; the males, as Professor Westwood observes, “are exceed- “ ingly ardent, seizing their partners round the neck “ with their sickle-shaped jaws ; ” 5 whilst the females use 5 These organs in the male often differ in closely-allied species, #i'd afford excellent specific characters. Hut their importance, under !l functional point of viow, as Mr. R. MacLaehlan lias remarked to tin • lias probahl.v been overrated. It has been suggested, that slight ‘111- ferencea in these organs would suffice to prevent the intercrossing nt well-marked varieties or incipient species, and would thus aid in tlicir development. 1'hat this can hardly be the case, we may infer from tb* many recorded eases (see for instance, Bronn, ‘Geschichte der Natur- B. ii. 1813, s. Kit; and Westwood, ‘Transact. Eat. 8oc.' vol. iii. lSi% p. I Do) of distinct species having been observed in union. SB- MacLaehlan informs me vide ‘Skit. Ent. Ztitung,’ 1867. s. 155) that when several species of Phryganidre. which present stiongly-prououn<’el1 differences of litis kind, were confined together by Dr. Aug. Mcyt‘r’ thei/ wm'pled, and one. pair produced fertile ova. s ‘Tho Practical Entomologist,’ Philadelphia, vol. ii. May, 186T» p. 88. 4 Mr. Walsh, ibid. p. 107. 5 ‘Modern Classification of Insects,’ vol. ii. 1840, p. 206,205. ^T‘ Walsh, who called my attention to this double use of the jaws, s"ys that he has repeatedly observed this fact. INSECTS. 343 C‘UP. X. these organs for burrowing in sand-banks and making their nests. . The tarsi of the front-legs are dilated m 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 much more Unusual circumstance that the females of some water- beetles (Dytiseus) have their olytra deeply grooved, and in Acilius sulcatus thickly set with hairs, as an aid to the male. The females of some other water-beetles (Hydro- porus) have their elytra Punctured for the same ob- ject.8 In the male of Cnibro crtbrarius (fig. 8.), it is the tibia which is dilated into a broad horny plate, with mi- Unte membraneous dots, giv- iiig to it a singular appear- ance like that of a riddle.' In the male of Penthe (a genus ot beetles) a lew 0I ' maUs. ^figure, female, fbe middle joints of the an- teimar are dilated and furnished on the inferior surface 8 We have here a euiiona ana Inexplicable ease of dimorphism, for s«me of the females of four European species of Dytiseus, and of certain species of Hydroporus, have their elytra smooth; and no intermediate gradations between sulcated or punctured and quite smooth elytra We been observed. See Dr. H. Schaiun, as quoted in the Zoologist, Vol. y.-vi. 1847-18, p. 1896. Also Kirby o.uIAP. X. INSECTS. S47 these exceptions are intelligible. Size and strength Would be an advantage to the males, which fight for the possession of the female ; and in these cases the males, as with the stag-beetle (Lucanus), are larger than the females. There are, however, other beetles which are Wot known to fight together, of which the males exceed the females in size; and the meaning of this iact is not known ; but in some of these cases, as with the huge klynastes and Megasoma, we can at least see that there Would be uo necessity tor the males to he smaller than tlie females, in order to he matured before them, for these beetles are not short-lived, and there woulu he •1 tuple time for the pairing of the sexes. So, again, male dragon-flies (Libellulidte) are sometimes sensibly larger, and never smaller, than the females; 18 and they do not, as Mr. MacLachlon believes, generally pair with the females, until a week or fortnight has elapsed, and until they have assumed their proper Wiascnline colours. But the most curious case, shewing °n what complex and easily-overlooked relations, so trifling a character as a difference in size between the sexes may depend, is that of the aculeate Hymenoptera ; for Mr. F. Smith informs me that throughout nearly Ike whole of this large group the males, in accor- dance with the general rule, are smaller than the females and emerge about a week before them , but amongst the Bees, the males of Apis viellifica, Anthidium ^anicatum and Anihophora acervorum, and amongst the k'ossores, the males of the Methoca ichneumonides, are larger than the females. The explanation of this ano- maly is that a marriage-flight is absolutely necessary 16 Eor this and other statements on the size of the sexes, see Kirby aad Spence, ibid. vol. iii. p. 300 ; on the duration of life in insects, See p. 314. 348 SEXUAL SELECTION. Part II- with these species, and the males require great strength and size in order to carry the females through the ah'- Increased size has here been acquired in opposition to the usual relation between size and the period of de- velopment, 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, Tliijsanura.—Uhe members of this Order are lowly organised for their class. They are wingless, dull-coloured* minute insects, with ugly, almost" mis- shapen heads and bodies. The sexes do not differ ; but they offer one interesting fact, by shewing that the males pay sedulous court to their females even low down in the animal scale. SirJ. Bubbock11 in describing th g Snu/ft' thurus luteus, says : “ it is very amusing to see these little creatures coquetting together. The male, which “ is much smaller than the female, runs round her, and “ they butt one another, standing lace to face, and £' moving backward and forward like two 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 hit they stand face to face, play with their “ antennae, and seem to be all in all to one another.” Order, Biftera (Flies).— The sexes differ little h1 colour. The greatest difference, known to Mr. F. Walker, 17 ‘Transact. Liunean Soc.’ vol. xxvi. 1868, p. 296. Wap. x. DIPTEEA AND HEMTPTEKA. 349 18 in the genus Bibio, in which the males are blackish 0r quite black, and the females obscure brownish-orange. The genus Elaphomyia, discovered by Mr. Wallace ls 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 stags, being either branched or palmated. They equal in length the whole of the body in one of the species. They might be thought to serve 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 pro- bable that the horns serve as ornaments. That the dales of some Diptera fight, together is certain ; for Prof. Westwood 19 has several times seen this with some sPecies of Tipula or Harry-long-legs. Many observers believe that when gnats (Oulicidas) dance in the air in a body, alternately rising and falling, the males are courting the females. The mental faculties of the >, o 1 hptera are probably fairly well developed, for their Nervous system is more highly developed than in most °ther Orders of insects.20 Order, Eemiptera (Field-Bugs).— Mr. J. W. Douglas, " ho has particularly attended to the British species, has biudlv given me an account of their sexual differences. The males of some species are furnished with wings, "didst the females are wingless ; the sexes differ in the f°rm of the body and elytra; in the second joints of their antennae and in their tarsi ; hut as the signification Is ‘ The Malay Archipelago,’ vol. ii. 1869, p. 313. 19 ‘ Modern Classification of Insects,’ vol. ii. 1840, p. 526. 50 See Mr. B. T. Lowne’s very interesting work, ‘ On tlie Anatomy of Blow-Fly, Mu sea vomitoria,’ 1870, p. 14. 350 SEXUAL SELECTION. Part II- of these differences is quite unknown, they may he 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 marked with vermilion and black. It is doubtful whether these colours serve as a protection- If in any species the males had differed from the females in an analogous manner, wre might have been justified in attributing such conspicuous colours to sexual selec- tion with transference to both sexes. Some species ofRednvidse make a strid dating noise! and, in the case of Pirates stridulus , this is said21 to be effected by the movement of the neck within the pro-thoracic cavity. According to Westring, Reduvii i$ personatus also stridulates. But I have not been able to learn any particulars about these insects; nor have I any reason to suppose that they differ sexually in this respect. Order, Eomoptera. — Every one who has wandered i'1 a tropical forest must have been astonished at the din made by the male Cicada?. The females are mute • as the Grecian poet Xenarchus says, “ Happy the “ Cicadas live, since they all have voiceless wives. The noise thus made could be plainly heard on board the “Beagle,” when anchored at a quarter of a niiD from the shore of Brazil ; and Captain Hancock sa)'s it can be heard at the distance of a mile. The Greek* formerly kept, and the Chinese now keep, these insect* 21 Westwood, ‘Modern Class, of Insects,’ vol. ii. p. 473. ClIAP. X. HOMOPTEKA. 351 in cages for tlie sake of their song, so that it must be pleasing to the ears of some men.22 The Cicadidse Usually sing during the day; whilst the Fulgoridse appear to be night-songsters. The sound, according to Landois,-' who has recently studied the subject, is produced by the vibration of the lips of the spiracles, which are set into motion by a current of air emitted from the trachea?. It is increased by a wonderfully complex resounding apparatus, consisting of two cavi- ties covered by scales. Hence the sound may truly be called a voice. In the female the musical apparatus is present, but very much less developed than in the ttiale, 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,24 “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.” He adds, “ this “ season (Aug. 1868) a dwarf pear-tree in my garden “ produced about fifty larvae of Cic. pruinosa ; and I “ several times noticed the females to alight near a “ male while he was uttering his clanging notes.” Fritz ^fuller writes to me Irom S. Brazil that he has often listened to a musical contest between two or three 'Wales of a Cicada, having a particularly loud voice, and seated at a considerable distance from each other. As 22 These particulars are taken from Westwood’s ‘Modem Class, of Insects’ vol, ii. 1840, p. 422. See, also, on the Fulgondas, Kirby and Spence, Introduct.’ vol. ii. p. 401. 23 ‘ Zeitschrift, fur wissenschatt. Zoolog.’ B. xvii. 18G7, s. 152-158. 21 1 am indebted to Mr. Walsh for having sent me this extiact from a ‘ Journal of the Doings of Cicada septemdecim,’ by Dr. Hartman. 352 SEXUAL SELECTION. ''Pabt II- soon as tlie first had finished his song, a second im- mediately began ; and after he had concluded, another began, and so on. As there is so much rivalry between the males, it is probable that the females not only dis- cover them by the sounds emitted, but that, like female birds, they are excited or allured by the male with the most attractive voice. I have not found any well-marked cases of orna- mental differences between the sexes of the Hoinoptera. 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, Orthopiera. — The males in the three salta- torial families belonging to this Order are remark- able for their musical powers, namely the Achetidie or crickets, the Locustidte for which there is no exact equivalent name in English, and the Acridiidm or grass- hoppers. The stridnlation produced by some of the Locus ti dm is so loud that it can be heard during the night at the distance of a mile;25 and that made bv 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 that the sounds serve either to call or excite the mute females. But h has been noticed20 that the male migratory locust of Russia (one of the Acridiidse) whilst coupled with the female, stridulates from anger or jealousy when ap" proached by another male. The house-cricket when surprised at night uses its voice to warn its fellows.27 1° North America the Katy-did ( PlatijphyUum concavuw, 25 L. Guilding, 1 Transact. Linn. Soc.’ vol. xv. p. 154. 56 Koppen, as quoted in the 1 Zoological Eecord,’ for 1867, p. 460. 27 Gilbert White, ‘ Nat. Hist, of Selborne,’ vol. ii. 1825, p. 262. ClUp. X. ORTHOPTERA. 353 °Re of the Locustidse) is described28 as mounting on the Upper branches of a tree, and in the evening beginning “ his noisy babble, while rival notes issue from the neigh- “ bouring trees, and the groves resound with the call of “ Katij-did-she-did, the live-long night.” Mr. Bates, in Epeaking of the European field-cricket (one of the Ache- bdee). says, “ the male has been observed to place itself “ in the evening at the entrance of its burrow, and “ stridulate until a female approaches, when the louder “ notes are succeeded by a more subdued tone, whilst “ the successful musician caresses with his antennas “the mate he has won.”2'J Or. Scudder was able to °Xeito one of these insects 1° answer him, by rubbing °n a file with a quill.80 In both sexes a remark- able auditory apparatus been discovered by Ion Siebold, situated in Hie front legs.31 In the three Families Wle sounds are differently I'fe. 10- Gryllus campestris (from Lnndois), Produced. In the males of Ino Achetidas both wing- c°vers have the same sh'Ucture ; and this in the field-cricket ( Gryllus campestris, fig. 10) consists, as de llight-lmnd figure, under side of part of the wing-nervure, much magnified, showing the teeth, st. Left-hand figure, upper surface of wing-cover, with the projecting, smooth nervure, r.t across which the teeth (st) are scraped. Harris, ‘ Insects of New England,’ 1S12, p. 128. *9 ‘ The Naturalist on the Amazons,’ vol. i. 1863, p. 252. Mr. Bates a very interesting discussion on the gradations in the musical apparatus of the three families. See also Westwood, ‘Modern Class.’ 7 *>■ p. 415 and 453. ° ‘ Proc. Boston Soc. of Nat. Hist.’ vol. xi. April, 1868. * 1 ‘Nouveau Manuel d’Anat. Comp.’ (French translat.), tom. i. 1850 P- 567. yOL. I. 2 A 354 SEXUAL SELECTION. Part H* Fig. 11. Teeth of Nervure of Gryllus domesticus (from Lundois). scribed by Landois,32 of from 131 to 138 sharp, trans- verse ridges or teeth (si) on the under side of one of the nervures of the wing-cover. This toothed nervure is rapidly scraped across a projecting, smooth, hard nervure (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 re- sonance. In some species the wing' covers of the males are furnished the base with a talc-like plate.® I have here given a drawing (fig. U) of the teeth on the under side of the nervure of another species of Gryllus, viz. G. domesticus. In the Locustidie the opposite wing-covers differ h1 structure (fig. 12), and cannot, as in the last family be indifferently used in a reversed manner. The led1 wing, which acts as the bow of the fiddle, lies over the right wing which serves as the fiddle itself. One o*' the nervures (a) on the under surface of the former k finely serrated, and is scraped across the prominent nervures on the upper surface of the opposite or rigid wing. In our British Fhasgonura viridissima it aP' peared to me that the serrated nervure is rubbo against the rounded hind corner of the opposite win-' the edge of which is thickened, coloured brown, very sharp. In the right wing, but not in the 1°^’ there is a little plate, as transparent as talc, surround® by nervures, and called the speculum. In Ephippi'J11' vitium, a member of this same family, we have a curio11- 32 1 Zeitschrift fur wissenschaft. Zoolog.’ B. xvii. 1867, s. 117. 33 AVeatwood, ‘ Modern Class, of Insects,’ vol. i. p. 440. Chap. X. ORTHOPTERA. 355 subordinate modification ; for the wing-covers are greatly reduced in size, but “ the posterior part of the pro-thorax “ is elevated into a kind of dome over the wing-covers, “ and which has probably the effect of increasing the “ sound.”34 We thus see that the musical apparatus is more differentiated or specialised in the Locustid®, which include I believe the most powerful performers in t'le Order, than in the Achctidse, in which both wing- covers have the same structure and the same function.35 dj&ndois, however, detected in one ot the Locustidse, Namely in Oecticus, a short and narrow row ot small si Westwood, ‘ Modern Class, of Insects,’ vol. i. p. 453. 35 Landois, ibid. s. 121, 122. 350 SEXUAL SELECTION. Part II- teeth, mere rudiments, on the inferior surface of the right wing-cover, which underlies the other and is never used as the bow. I observed the same rudi- mentary structure on the under side of the right wing- cover in Phasgonura viridissima. Hence we may with confidence infer that the Locustidse are descended from a form, in which, as in the existing Achetidfe, both wing-covers had serrated nervures on the under surface, and could be indifferently used as the bow ; but that in the Locustidse the two wing-covers gradually became differentiated and perfected, on the principle of the divi- sion of labour, the one to act exclusively as the bow and the other as the fiddle. By what steps the more simple apparatus in the Aehetidm originated, we do not know, hut it is probable that the basal portions of tlie wing- covers overlapped each other formerly as at present, and that the friction of the nervures produced a grating sound, as I find is now the case with the wing-covers of the females.36 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 fitting variations in the roughness of the nervures bavins: been continually preserved. In the last and third Family, namely the Acridiid# or grasshoppers, the stridulation is produced in a very different manner, and is not so shrill, according to Pr' Scudder, as in the preceding Families. The inner sur- face of the femur (fig. 13, r ) is furnished with a longi- tudinal row of minute, elegant, lancet-shaped, elastic teeth, from 85 to 93 in number ;37 and these are scraps 315 Mr. Walsh also informs me that he lias noticed that the female of the Platyphyllum concavum, “ when captured makes a feeble grating “ noise by shuffling her wing-covers together.” 37 Landois, ibid. s. 11:1. Chap. x. ORTHOPTERA. 357 Fig. 13. Hind-leg of Stenobothrus pratorura r, the Btridulattng ridge ; lower figure, the teeth, forming the ridge, much magnified (from Ijandois). across the sharp, projecting nervures on the wing-covers, 'vhich are thus made to vibrate and resound. Harris3 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 “ Addles together, but al- “ ternately first upon one “ and then on the other.” la many species, the base °f the abdomen is hollowed out into a great cavity "'hich is believed to act as a resounding board. In hneumora (fig. 14), a S. African genus belonging to mis same family, we meet with a new and remarkable Modification : in the males a small notched ridge pro- jects obliquely from each side of the abdomen, against "hich the hind femora are rubbed.39 As the male is burnished with wings, the female being wingless, it is Mruarkable that the thighs are not rubbed in the usual Manner against the wing-covers ; but this may perhaps accounted for by the unusually small size of the hind- W- I have not been able to examine the inner 8Mface of the thighs, which, judging from analogy, "‘ould be finely serrated. The species of Pneumora We been more profoundly modified lor the sake of 'Hidulatiou than any other orthopterous insect ; for 33 1 Insects of New England,’ 1812, p. 133. 39 Westwood, ‘Modern Classification,’ vol. i. p. 462. 358 SEXUAL SELECTION. Part Il- ia the male the whole body has been converted into a musical instrument, being distended with 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. Fig. 14. Pneumora (from specimens in the British Museum). Upper figure, m^e’ lower figure, female. There is one exception to the rule that the femal^ in these three Families are destitute of an efficie11 musical apparatus ; for both sexes of Ephippiger (f0 custidie) are said40 to be thus provided. This case virf 40 Westwood, ibid. vol. i. p. 453. CiUr. X. ORTHOPTERA. 359 be compared with that of the reindeer, in which species alone both sexes possess horns. Although the female orthoptera are thus almost invariably mute, yet Landois41 found rudiments of the stridulating organs on the fe- mora of the female Acridiidse, and sirni lar rudiments on the Under surface of the wing-covers ot the female Achetidse ; but he failed to find any rudiments in the females of Decticus, one of the Locustid®. In the Homoptera the mute females of Cicada have the proper musical apparatus in an undeveloped state; and we shall here- after meet in other divisions ot the animal kingdom with innumerable instances of structures proper to the male being present in a rudimentary condition in the female. Such cases appear at first sight to indicate that both sexes were pri mordially constructed in the same manner, but that certain organs were subsequently lost by the females. It is, however, a more probable view, as pre- viously explained, that the organs in question were acquired by the males and partially transferred to the females. Landois has observed another interesting fact, namely that in the females of the Acridiid®, the stridulating teetli on the femora remain throughout life in the same condition in which they first appear in both sexes during the larval state. In the males, on the other- band "they become fully developed and acquire their perfect structure at the last moult, when the insect is feature and ready to breed. From the facts now given, we see that the means by which the males produce their sounds are extremely diversified in the Orthoptera, and arc altogether dif- ferent from those employed by the Homoptera. But throughout the animal kingdom we incessantly find the O 41 Landois, ibid. s. 115, 116, 120, 122. 360 SEXUAL SELECTION. Part II- same object gained by the most diversified means; this being due to the whole organisation undergoing in the course ot ages multifarious changes; and as part alter part varies, different variations are taken advantage of for the same general purpose. The diversification of the means for producing sound in the three families of the Oi thoptera and in the Homoptera, impresses the mmd with the high importance of these structures to the males, for the sake ot calling or alluring the females. ^ ® 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,1' 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 “ tlj<; well-known tympanum or stridulating apparatus “ of the male Locust him.” This insect, though in most respects related to the Neuroptera, appears to connect, as is so often the case with very ancient forms, the two Orders of the Neuroptera and Orthoptera which are now generally ranked as quite distinct. ^ I have but little more to say on the Orthoptera- Some of the species are very pugnacious: when two male field-crickets ( Gryllus campestris ) are confined together, they fight till one kills the other; aud the species ol Mantis are described as manoeuvring 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.43 With respect to colour, some exotic locusts are beautifully orna- mented ; the posterior wings being marked with red, p * ransact- Ent. Soc.’ 3rd series, vol. ii. p Journal of Proceedings, 3 ^Westwood, ‘Modern Class, of Insects,’ vol. i. p. 427; for crickets, Chap. X. NE U IiOPTIfi LiA. 361 blue, and black; but as throughout the Order the two sexes rarely differ much in colour, it is doubtful whether they owe these bright tints to sexual selection. Conspicuous colours may be of use to these insects as a protection, on the principle to be explained in the next chapter, by giving notice to their enemies that they are unpalatable. Thus it has been observed44 that an Indian brightly-coloured locust was invariably rejected when offered to birds and lizards. Some cases, however, of sexual differences in colour in this Order are known. The male of an American cricket41 is de- scribed 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 (ono 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 40 is furnished with “ a long membranous appendage, which falls over the “ face like a veil ; ” but whether this serves as an orna- ment is not known. Order, Neuroptera. — Little need here be said, except in regard to colour. Iu the Ephemeral® the sexes often differ slightly in their obscure tints;47 but it is Hot probable that the males are thus rendered attrac- tive to the females. The Libel lulidse or dragon-flies me ornamented with splendid green, blue, yellow, and 14 Mr. Cli. Horne, in ‘ Proc. Ent. Soc.’ May 3, 1809, p. xii. 4o Tlie Oecauthus nivalis. Harris, 1 Insects of New England,’ 1 S42, P. 124. H Platyblenmus : Westwood, ‘ Modern. Class.’ vol. i. p. 447. 47 B. D. Walsh, the Pseudo-neuroptera of Illinois, in ‘Proc. Ent. Soc. of Philadelphia,’ 18G2, p. 3G1. 3B2 SEXUAL SELECTION. Part II. vermilion metallic tints; and the sexes often differ. Thus, the males of some of the Agrionidae, as Prof. Westwood remarks/8 “are of a rich blue with black “ wings, whilst the females are line green with colourless “wings.” Put in Agrion Ramburii these colours are exactly reversed in the two sexes.49 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 ultra-marine 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. Throughout the animal kingdom, similar cases of the sexes of closely-allied forms either differing greatly, or very little, or not at all, are of frequent occurrence. Although with many Libellulidse there is so wide a difference in colour between the sexes, it is often difficult to say which is the most brilliant; and the ordinary coloration of the two sexes is exactly 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. As Mr. MacLachlan, who has closely attended to this family, writes to me, dragon- flies— the tyrants of the insect-world — are the least liable of any insect to be attacked by birds or other enemies. He believes that their bright colours serve as a sexual attraction. It deserves notice, as bearing on this subject, that certain dragon-flies appear to be attracted by particular colours : Mr. Patterson observed30 that the species of Agrionidm, of which the males are blue, settled in numbers on the blue float of a fishing 48 ‘ Modern Class.’ vol. ii. p. 37. 49 Walsh, ibid. p. 881. I am indebted to this naturalist for tbo folio-wing- facts on Hetserina, Anas, and Gomphus. 60 1 Transact. Ent. Soc.’ vol. i. 1836, p. lxxxi. Chap. X. NEUROPTEEA. line ; whilst two other species were attracted by shining white colours. It is an interesting fact, first observed by Sclielver, that the males, in several genera belonging to two sub- families, when they first emerge from the pupal state are coloured exactly like the females ; but that their bodies in a short time assume a conspicuous milky-blue tint, owing to the exudation of a kind of oil, soluble in ether and alcohol. Mr. MacLaehlau believes that in the male of Libellula depressa this change of colour does not occur until nearly a fortnight after the metamorphosis, when the sexes are ready to pair. Certain species of Neurothemis present, according to Brauer51 a curious case of dimorphism, some of the females having their wings netted in the usual manner ; whilst other females have them “ very richly netted as in “ the males of the same species.” Brauer “ explains “ the phenomenon on Darwinian principles by the “ supposition that the close netting of the veins is a “ secondary sexual character in the males.” This latter character is generally developed in the males alone, but being, like every other masculine character, latent in the female, is occasionally developed in them. We have here an illustration of the manner in which the two sexes of many animals have probably come to resemble each other, namely by variations first appear- ing in the males, being preserved in them, and then transmitted to and developed in the females ; but in this particular genus a complete transference is occa- sionally and abruptly effected. Mr. MacLachlan in- forms me of another case of dimorphism occurring in several species of Agrion in which a certain number ot individuals are found ot an orange coloui, and these are 51 See abstract in the ‘Zoological Becord ’ for 18G7, p. 450. 364 SEXUAL SELECTION. Part II. invariably females. This is probably a case of reversion, lor in the true Libellulse, when the sexes differ in colour, the females are always orange or yellow, so that supposing Agrion to be descended from some pri- mordial form having the characteristic sexual colours of the typical Libelluke, it would not be surprising that a tendency to vary in this manner should occur in the females alone. Although many dragon-flies are such large, powerful, and fierce insects, the males have not been observed by Mr. MacLachlan to fight together, except, as he believes, in the case of some of the smaller species of Agrion. In another very distinct group in this Order, namely in 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.” 52 Order, Hymenojotera.— That inimitable observer, M. Fabre,’J in describing the habits of Cerceris, a wasp- like insect, remarks that “ fights frequently ensue between the males for the possession of some parti- ‘ cl*lar 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 54 says that the males of one of the saw-flies (Tenth rcdiiuc) “ have beeu “ found fighting together, with their mandibles locked.” As M. I’abi'e speaks of the males of Cerceris striving to obtain a particular female, it may be well to bear in Kirby and Spence, ‘ Introduct. to F.utomology,’ vol. ii. 1818, p. 35. ,J See an interesting article, “ Tire Writings of Fubre,” in 1 Nat. Hist. Keview,’ April, 1882, p. 122. ‘Journal of Proc. of Entomolog. Soc.’ Sept. 7th, 18(13, p. 109. Chap. X. HYMENOPTERA. 365 mind that insects belonging to this Order have the power of recognising each other after long intervals of time, and are deeply attached, if or instance, Pierre Huber, 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 mutually recognised and caressed each other 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 in the general confusion sometimes attack each other, but they soon perceive their mistake, and the one ant soothes the other.55 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 m Chrysis, in which vermilion and metallic greens Prevail — that we are tempted to attribute the result to sexual selection. In the Ichneumonidse, according to Hr. Walsh,58 the males are almost universally lighter coloured than the females. On the other hand, in the Tenthredinidue the males are generally darker than the females. In the Siricidm the sexes frequently differ; thus the male of Sirex juvencus is banded with orange, "hi 1st the female is dark purple ; but it is difficult to say which sex is the most ornamented. In Tremex columbm the female is much brighter coloured than the "nile. With ants, as I am informed by Mr. F. Smith, the males of several species are black, the females being testaceous. In the family of Bees, especially in 55 P. Huber, ‘Kecherches sur les Moeurs des Fourmis,’ 1810, p. 150, 165. 56 ‘ Pvoc. Entomolog. Soc. of Philadelphia,’ 18GG, p. 238-239. 366 SEXUAL SELECTION. Part II. the solitary species, as I hear from the same distin- guished entomologist, the sexes often differ in colour. The males are generally the brightest, and in Bombus as well as in Apathus, much more variable in colour than the females. In Anthophora retusa 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. In an Australian bee ( Lest/is bombylans), the female is of an extremely brilliant steel-blue, sometimes tinted with vivid green ; the male being of a bright brassy colour clothed with rich fulvous pubescence. As in this group the females are provided with excellent defensive weapons in their stings, it is not probable that they have come to differ in colour from the males for the sake of protection. Mutilla Europtm emits a stridulating noise ; and ac- cording to Goureau 57 both sexes have this power. Be attributes the sound to the friction of the third and preceding abdominal segments; and I find that these surfaces are marked with very fine concentric ridges, but so is the projecting thoracic collar, on 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, as do some dipterous insects ; but I have not referred to these sounds, as they are not known to be in any way connected with the act of courtship. Order, Coleoptera (Beetles). — Many beetles are coloured so as to resemble the surfaces which they 57 Quoted by Westwood, ‘Modern Class, of Insects,’ vol. ii. p. 211. Chap. X. COLEOPTEEA. 367 habitually frequent. Other species are ornamented with gorgeous metallic tints, — for instance, many Cara- bidte, which lire on the ground and have the power of defending themselves by an intensely acrid secretion, —the splendid diamond-beetles which are protected by an extremely hard covering, — many species of Chry- somela, such as 0. cerealis, a large species beautifully striped with various colours, and in Britain confined to the bare summit of Snowdon, — and a host of other species. These splendid colours, which are often arranged in stripes, spots, crosses and other elegant patterns, can hardly he beneficial, as a protection, except in the case of some flower-feeding species; and we cannot believe that they are purposeless. Hence the suspicion arises, that they serve as a sexual attraction ; but we have no evidence on this head, for the sexes rarely differ in colour. Blind beetles, which cannot of course behold each other’s beauty, never exhibit, as I hear from Mr. Waterhouse, jun., bright colours, though they often have polished coats : but the explanation of their obscurity may he that blind insects inhabit caves and other obscure stations. Some ' Longicorns, however, especially certain Pri- onidrn, offer an exception to the common rule that the sexes of beetles do not differ in colour. Most of these insects are large and splendidly coloured. 1 he males in the genus Pyrodes,58 as I saw in Mr. Bates collection, are 58 Pyrodes pulcherrimus, in which tlie sexes differ conspicuously, has been described by Mr. Bates in ‘ Transact. Eut. Soc.’ 1809, p. 50. I WiU specify tiro few other cases in which T have heard oi a difference >n colour between the sexes of beetles. Kirby and , Spence (‘ Introduct. to Entomology,’ vol. iii. p. 301) mention a Cantharis, Mcloe, Rhagium, and the Leptura testacea ; the male of tiro latter being testaceous, with a black thorax, and the female ot a dull red all over. These two tatter beetles belong to the Order of Longicorns. Messrs. It. Trimen and Waterhouse, junr., inform mo of two Lamellicorns, viz., a Peri- 36‘S SEXUAL SELECTION. Part II. 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 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. Fig. 15. trichia and Trichius, the male of the latter being more obscurely coloured than the female. In Tillux i.hmgatiis the male is black, and the female always, as it is believed, of a. dark blue colour with a red thorax. The male, also, of Onnflacna atra , ns I hear from Mr. Walsh, is black, the female (the so-called 0. ruficullis ) having a rufous thorns. Chalcosoma atlas, Upper figure, male (reduced) ; lower figure, female (nat. size). chap. X. COLEOPTERA. f i Copris isidis. (Left-hand figures, males.) I'ig. 11. lMianauis faun us. K'g 18. Dipelicus canton. pig. 19. VOL. T. Onthophagus ranglfer. enlarged. 370 SEXUAL SELECTION. Part U- A most remarkable distinction between the sexes of many beetles is presented by the great horns which rise from the head, thorax, or clypeus of the males; and in some few cases from the under surface of the body. These horns, in the great family of the Lamelli- corns, resemble those of various quadrupeds, such as stags, rhinoceroses, &e., and 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 remarkable forms. (Figs. 15 to 19.) Tiie females generally exhibit rudiments of the horns in the form of small knobs or ridges; but some are destitute of even a rudiment. On the other hand, the horns are nearly as well developed in the female as in the male of Phanmm lancifer ; and only a little less well developed in the females of some other species of the same genus and of Copris. In the several sub- divisions of the family, the differences in structure of the horns do not run parallel, as I am informed by Mr. Bates, with their more important and characteristic differences ; thus within the same natural section of the genus Onthophagus, there are species which have either a single cephalic horn, or two distinct horns. In almost all cases, the horns are remarkable from their excessive variability; so that a graduated series can be formed, from the most highly developed males to others so degenerate that they can barely be distin- guished from the females. Mr Walsh59 found that m PhcmxMS carnifex the horns were thrice as long in sonio males as in others. Mr. Bates, after examining above a hundred males of Onthophagus rangifer (fig. 19)> thought that he had at last discovered a species i" S9 ‘ Proc. Entomolog. Soe. of Philadelphia,’ 1864, p. 228. Chap. X. COLEOPTERA. 371 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 important purpose; hut their excessive variability in the males of the same species leads to the inference that this purpose cannot he of a definite nature. The horns do not show marks of friction, as if used for any ordinary work. Some authors suppose'10 that as the males wander much more than the females, they require horns as a defence against their enemies; but in many eases the horns do not seem well adapted for defence, as they are not sharp. The most obvious conjecture is that they are Used by the males for fighting together; hut they have never been observed to fight; nor could Mr. Hates, 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, their size would probably have been increased through sexual selection, so as to have exceeded that of the female ; but Mr. Bates, after Comparing the two sexes in above a hundred species of the Copridse, does not find in well-developed individuals any marked difference in this respect. There is, more- over, one beetle, belonging to the same great division of the LameUicorns, namely Lethrus, the males of which are known to fight, but they are not provided with horns, though their mandibles are much larger than those of the female. The conclusion, which best agrees with the lact oi the horns having been so immensely yet not fixedly developed, — as shewn by their extreme variability in Kirby and Sponce, ‘ Introduct. Entomolog.’ vol. iii. p. 300. 2 B 2 co 372 SEXUAL SELECTION. Part li- the same species and by their extreme diversity in closely-allied species — is that they have been acquired as ornaments. 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 Onitis furcifer (fig. 20) are furnished with singular projections on their anterior femora, and body, yet in the females a rudiment of a single horn on the head (fig. 21, a), and of a crest (b) on the thorax, are plainly visible. That the slight thoracic crest in the Fig. 21. Left-band figure, male of Onitis furcifer, viewed laterally. Right-hand figure female. a. Rudiment of cephalic horn. &. Trace of thoracic horn or crest. female is a rudiment of a projection proper to the male* though entirely absent in the male of this particular species, is clear : for the female of Bubas bison (a form horns on the upper surface of the Chap. X. COLEOPTERA. 373 which comes next to Onitis) lias a similar sliglit crest' on the thorax, and the male has in the same situation a great projection. So again there can be no doubt that the little point (a) on the head of the female Onitis furcifer, as well 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 lamel- licorn beetles, as in Phameus, fig. 17. The males indeed of some unnamed beetles in the Rritish Museum, which are believed actually to belong to the genus Onitis, are furnished with a similar horn. The remarkable nature of this case will be best perceived by an illustration : the Ruminant quadrupeds run parallel with the larnel- licorn beetles, in some females possessing horns as large us those of the male, in others having them much smaller, or existing as mere rudiments (though this is Us rare with ruminants as it is common with Lamelli- Corns), or in having none at all. Now if a new species of deer or sheep were discovered with the female bearing distinct rudiments of horns, whilst the head of the male was absolutely smooth, we should have a case like that of Onitis furcifer. In this case the old belief of rudiments having been created to complete the scheme of nature is so far from bolding good, that all ordinary rules are completely broken through. The view which seems the most pro- bable is that some early progenitor of Onitis acquired, like other Lamellicorns, horns on the head and thorax, and then transferred them, in a rudimentary condition, as with so many existing species, to the female, by whom they have ever since been retained. The subsequent loss of the horns by the male may have resulted through fbe principle of compensation from the development of the projections on the lower surface, whilst the female bag not been thus affected, as she is not furnished with 374 SEXUAL SELECTIONS Pakt IL these projections, and consequently has retained the rudiments of tho horns on the upper surface. Although this view is supported by the case of Bledius imme- diately to he given, yet the projections on the lower surface differ greatly in structure and development in the males of the several species of Onitis, and are even rudimentary in some ; nevertheless the upper surface in all these species is quite destitute of horns. As secondary sexual characters are so eminently variable, it is possible that the projections on the lower surface may have been first acquired by some progenitor of Onitis and produced their effect through compensation, and then have been in certain cases almost completely lost. All the cases hitherto given refer to the Lamelli' corns, but the males of some few other beetles, be- longing to two widely distinct groups, namely, the Curculionidm and Staph y] in idee, are furnished with horns— in the former on tiie lower surface of the body,61 in the latter on the upper surface of the head and thoiax. In the Staphylinidse the horns of the males in the same species are extraordinarily variable, just as we have seen with the Lamellicorns. In Siagoniu® 22. Bledius tauvus, magnified. Beft-liand figure, male ; riglit-band figure, female- we have a case of dimorphism, for the males can be divided into two sets, differing greatly in the size ot their bodies, and in the development of their horny without any intermediate gradations. In a species of Bledius (fig. 22), also belonging to the Staphvlinid®, male specimens can be found in the same locality, aS 61 Kirby and Spence, ibid. vol. iii. p. 329. Chap. X. COLEOPTEEA. 375 Professor Westwood states, “ 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.”62 Here, then, we apparently have an instance of compensation of growth, which throws light on the curious case just gi ven of the loss of the upper horns by the males oi Onitis furcffer. Law of Battle.— Some male beetles, which seem ill fitted for fighting, nevertheless engage in conflicts ■ for the possession of the females. Mr. Wallace 05 saw two males of Leptorhynchus angustatm , a linear beetle with a much elongated rostrum, “fighting lor a female, who “ stood close by busy at her boring. They pushed at “ each other w ith their rostra, and clawed and thumped, “ apparently in the greatest rage.” The smaller male, however, “soon ran away, acknowledging himselt van- quished.” In some few cases the males are well adapted for fighting, by possessing great toothed man- dibles, 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 period they engage in fierce conflicts. When Mr. A. I . Davis64 enclosed two males with one female in a box, the larger male severely pinched the smaller one, until he resigned his pretensions. A friend informs me 62 ‘Modern Classification of Insects,' vol i. p. 172 On the same page there is an account of Siagonium. In the Brit sli Museum I noticed one male specimen of Siagonium m an intermediate condition, so that the dimorphism is not strict. 03 ‘ The Malay Archipelago,’ vol. ii. 1839, p- 270. M < T*1 r, t nm nlnodnal Magazine,’ vol. i. 1833, p. hee also on the conflicts of this species, Kirby and Spence, ibid. vol. iii. p. 314; and tVestwood, ibid. vol. i. p. 1S7. 376 SEXUAL SELECTION. Part II> that when a boy he often put the males together to see them fight, and lie noticed that they were much bolder and fiercer than the females, as is well known to be the case with the higher animals. The males would seize hold of his finger, if held in front, but not so the females. With many of the Lucanidae, as well as with the above- mentioned Leptorhynchns, the males are larger and more powerful insects than the females. The two sexes of Lethrus cephalotes (one of the Lamellicoms) inhabit the same burrow ; and the male has larger mandibles than the female. If, during the breeding-season, a strung® male attempts to enter the burrow, he is attacked; the female does not remain passive, but closes the mouth ot the burrow, and encourages her mate by continually pushing him on from behind. The action does not cease until the aggressor is killed or runs awav.65 The two sexes of another lamellicorn beetle, the Ateuch ** cicatrieosus 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 d she is removed, he becomes much agitated. If the male is removed, the female ceases all work, and a® M. Brulerie06 believes, would remain on the spot until she died. The great mandibles of the male Lucanidae are ex- tremely variable both in size and structure, and in tliig respect resemble the horns or the head and thorax of many male Lamellicorns and Stapliylinidre. A per- fect series can be formed from the best-provided to the worst-provided or degenerate males. Although the mandibles of the common stag-beetle, and probably of 03 Quoted from Fiselier, in ‘ Diet. Class. d’Hist. Nat.’ tom. x. p. 324- 60 ‘Ann. Soc. Eutomolog. France,’ 1866, as quoted in ‘Journal Travel,’ by A. Murray, 1868, p. 135. Chap. X. COLEOPTEKA. 377 many other species, are used as efficient weapons for fighting, it is doubtful whether their great size can thus be accounted for. \\ e have seen that with the Lucanus da- phus of N. America they are used for seizing the female. As they are so conspicuous and so ele- gantly branched, the suspicion has sometimes crossed my mind that they may be serviceable to the males as an ornament, in the same manner as the horns on the head and thorax of the various above described species. The male Chiasognatlms grantii of S. Chile — a splendid beetle belong- ing to the same family — has enor- mously-developed mandibles (fig. 23) ; lie is bold and pugnacious ; When threatened on any side lie faces round, opening his great jaws, and at the same time stridu- lating loudly ; hut the mandibles were not strong enough to pinch my finger so as to cause actual pain. Sexual selection, which implies the possession of considerable per- ceptive powers and of strong pas- sions, seems to have been more effective with the Lamellicorns than with any other family of the Coleoptera or beetles. With some species tlie males are provided with weapons for fight- ing ; some live in pairs and show mutual affection ; Fig. 23. ChmsogTMtlius grantii, reduced. U pper figure, male ; lower figure, female. 378 SEXUAL SELECTION. Pakt li- man y have the power of stridnlating when excited ; many are furnished with the most extraordinary horns, appa* rently for the sake of ornament ; some which are diurnal in their habits are gorgeously coloured ; and, 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 of the Coleoptera.07 Siridulating organs. — Beetles belonging to many and widely distinct families possess these organs. The sound can sometimes be heard at the distance of several feet or even yards,08 but is not comparable with that produced by the Orthoptera. The part which may be called the rasp generally consists of a narrow slightly- raised surface, crossed by very fine, parallel ribs, some- times so fine as to cause iridescent colours, and having a very elegant appearance under the microscope. I11 some cases, for instance, with Typhceus, it could be plainly seen that extremely minute, bristly, scale-like prominences, which cover the whole surrounding sur- face in approximately parallel lines, give rise to the ribs of the rasp by becoming confluent and straight, and at the same time more prominent and smooth. A hal'd ridge on any adjoining part of the body, which in son>e cases is specially modified for the purpose, serves as the scraper for the rasp. The scraper is rapidly moved across the rasp, or conversely the rasp across the scraper. These organs are situated in widely different posi- tions. In the carrion-beetles (Necrophorus) two parallel rasps (r, fig. 24) stand on the dorsal surface of the fiffb abdominal segment, each rasp being crossed, as described by Landois,69 by from 12(3 to 140 fine ribs. These 6? Westwood, * Modern Class.’ vol. i. p. 184. j. r>s Wollaston, On certain musical Curculionidse, ‘Annals and Mag- 0 Nat. Hist.’ vol. vi. 1860, p. 14. sn ‘ Zeitsohrift fur wiss. Zoolog.’ B. xvii. 1807, s. 127. (lHAP. X. coleoptera. 379 ribs are scraped by tlie posterior margins of the elytra, a small portion of which projects beyond the general out- line. In many Crioceridte, and in Clyihra k-punctata Fig. 24. Necropliorus (from Landois). r. The two rasps. Left-hand figure, part of the rasp highly magnified. (one of the Chrysomeliilse), and in some Tenebrionidae, &c\,70 the rasp is seated on the dorsal apex of the abdo- men, on the pygidium or pro-pygidium, and is scraped as above 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.71 In certain Curculionidae and Cara- bidte,72 the parts are completely reversed in position, 70 I urn greatly indebted to Mr. G. K. Crotch for haying sent me hunierous prepared specimens of various beetles bdongimr to these three families and others, ns well as for valuable information of nil kinds. He believes that the power of stimulation in the Clyihra has not been pre- viously observed. lam also much indebted to Mr. E. IV. Jnnson, for information and specimens. I may add that my son, Mr. F. Darwin, buds that Dermestes murinns stridulatcs, hut he searched in vain for the apparatus. Scoiytus has lately been described by Dr. Chapman as a stridulator, in the * Entomologist’s Monthly Magazine,’ vul. vi. p. 130. 71 Scliiodte, translated in ’Annals and Mag. ot Nat. Hist. vol. xx. f&67, p. 37. 72 Westring has described (Kroyer, ‘Naturbist. lidskrilt, B. ii. 1848- 10, p, syl) the stridulating organs in these two, as well as in other families. In the Carabidar I have examined Elaphrui uliginoews and J'b-thisa multipunctata, sent to me by Mr. Crotch. In l.lethisa the transverse ridges on the furrowed border of tlie abdominal segment do n«t come interplay, as far as I could judge, in scraping tlie rasps on tho elytra. 380 SEXUAL SELECTION. Part II- for tlie 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 Pelobius he.rma.nni (one of Dytiscidse 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 scraping the extreme horny margin of the abdomen against the rasp. In a great number of long-homed beetles (Longicornia) the organs are alto- gether differently situated, the rasp being on the meso- thorax, which is rubbed against the pro-thorax ; Landois counted 238 very line ribs on the rasp of Ceraniby isis the difference between the sexes is more strongly parked, and this is best seen when the proper segment ls cleaned and viewed as a transparent object. In the female the whole surface is covered with little separate Cl'ests, bearing spines ; whilst in the male these crests 884 SEXUAL SELECTION. Part II- become, in proceeding towards the apex, 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, when the abdomen of a softened specimen is pushed back- wards and forwards, a slight grating or stridulating sound can be produced. 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 apparently serves both sexes as a mutual call. This view is not rendered improbable from beetles stridulating under various emotions ; we know that birds use their voices for many purposes besides singing to their mates. The great Chiasognathus stridulates h1 anger or defiance ; many species do the same from dis- tress or fear, when held so that they cannot escape ! Messrs. Wollaston and Crotch were able, by striking the hollow stems of trees in the Canary Islands, to dis- cover the presence of beetles belonging -to the genus Acalles by their stridulation. Lastly the male AteU- chus stridulates to encourage the female in her work and from distress when she is removed/1 Some natu- ralists believe that beetles make this noise to frighten away their enemies ; but I cannot think that the quadru- peds and birds which are able to devour the larg®r beetles with their extremely hard coats, would be fright' ened by so slight a grating sound. The belief that the stridulation serves as a sexual call is supported by the fact that death-ticks (Anolium tessdlatuni ) are well known to auswer eacli other’s ticking, or, as I have 74 M. P. de la Brulerie, as quoted in 1 Journal of Travel,’ A. Murr®)’ vol. i. 1808, p. 13o. Chap. X. COLEOPTERA. 385 myself observed, a tapping noise artificially made ; and Mr. Doubleday informs me that he has twice or thrice observed a female ticking,75 and in the course of an hour or two has found her united with a male, and on one Occasion surrounded by several males. Finally, it seems probable that the two sexes of many kinds of beetles "ere at first enabled to find each other by the slight shuffling noise produced by the rubbing together of the adjoining parts of their hard bodies ; and that as the males or females which made the greatest noise suc- ceeded best in finding partners, the rugosities on various parts of their bodies were gradually developed by means of sexual selection into true stridulatiug organs. 75 Mr. Doubleday informs mo that “the noise is produced by the “ insect raising itself on its legs as high as it can, and then striking its ' thorax five or six times, in rapid succession, against the substance upon which it is sitting.” For references on this subject see Landois, Zeitsohrift fur wisson. Zoolog.’ B. xvii. s. 131. Olivier says (as quoted “V Kirby and Spence, ‘Inlroduct.’ vol. ii. p. 395) that the female of 1'imeliu striata produces a rather loud sound by striking her abdomen flgaiust any hard substance, “ and that the male, obedient to this call, 11 soon attends her and they pair.” SEXUAL SELECTION. Part #• 386 CHAPTER XI. Insects, continued. — Order Lepidopteea. Courtship of butterflies — Battles — Ticking noise — Colours coni' mon to both, sexes, 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 — Per- ceptive powers of the Lepidoptera — Variability — Causes of the difference in colour between the males and females — Mimickry, female butterflies more brilliantly coloured than the males-' Bright colours of caterpillars — Summary and concluding re- marks on the secondary sexual characters of insects — Birds and iusects compared. In this great Order the most interesting point for us is the difference in colour between the sexes of the sai»e species, and between the distinct species of the sai»e genus. Nearly the whole of the following chapter will he devoted to this subject ; but I will first make a fe'v remarks on one or two other points. Several males run/ often be seen pursuing and crowding round the san>e female. Their courtship appears to be a prolonged affair for I hare frequently watched one or more males pirouet- ting round a female until I became tired, without seeing the end of the courtship. Although butterflies are such weak and fragile creatures, they are pugnacious, and a» Emperor butterfly 1 * * has been captured with the tips of its wings broken from a conflict with another male- Mr. Collingwood in speaking of the frequent battle5 1 Apatura Iris : •' The Entomologist’s Weekly Intelligencer,' IS59’ p. 1SU. For the Bornean Butterflies see C. Collingwood, ‘Gambles0* a Naturalist,’ 1868, p. 183. Chap. XI. BUTTERFLIES AND MOTHS. 387 between the butterflies of Borneo says, They whirl “ round each other with the greatest rapidity, and appear “ to he incited by the greatest ferocity.” One case is known of a butterfly, namely the Ageronia feronia, which makes a noise like that produced by a toothed "heel passing under a spring catch, and which could be heard at the distance of several yards. At Bio de Janeiro this sound was noticed by me, only when two were chasing each other in an irregular course, so that it is probably made during the courtship of the sexes ; but I neglected to attend to this point.2 Every one has admired the extreme beauty of many butterflies and of some moths ; and we are led to ask, how has this beauty been acquired ? Have their colours and diversified patterns simply resulted from the direct action of the physical conditions to which these insects have been exposed, without any benefit being thus de- rived? Or have successive variations been accumulated and determined either as a protection or for some un- known purpose, or that one sex might be rendered attractive to the other ? And, again, what is the mean- ing of the colours being widely different in the males and females of certain species, and alike in the two sexes of other species? Before attempting to answer these questions a body of facts must be given. With most of our English butterflies, both those which are beautiful, such as the admiral, peacock, and painted lady (Vanessas), and those which are plain-coloured, 8Uch as the meadow-browns (Hipparchiae), the sexes are alike. This is also the case with the magnificent lieliconidas and Dana idle of the tropics. But in certain 2 See my ‘Journal of Researches,’ 1815, p. 33. Mr. Doubleday lias 'ktected (‘ Proc. Eut. Soc.’ March 3rd, 1845, p. 123) a peculiar mem- llranou3 sac at the base of the front wings, which is probably cou- nted with the production of the sound. 2 c 2 388 SEXUAL SELECTION. Part II. other tropical groups, and with some of our English butterflies, as the purple emperor, orange-tip, &c. (Apa- turn Iris and Anfhocharis cardamines), the sexes differ either greatly or slightly iu colour. No language suffices to describe the splendour of the males of some tropical species. Even within the same genus we often find spe- cies presenting an extraordinary difference between the sexes, whilst others have their sexes closely alike. Thus in the South American genus Epicalia, Mr. Bates, to whom I am much 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 therefore cannot have been dif- ferently affected by external conditions.15 In nine ot these species the males rank amongst the most brilliant of all butterflies, and differ so greatly from the compa- ratively 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 likewise resemble both sexes in several allied genera* found in various parts of the world. Hence in accord- ance with the descent-theory we may infer that the»t! nine species, and probably all the others of the genu4* are descended from an ancestral form which was coloured iu nearly the same manner. In the tenth species th0 female still retains the same general colouring, hut the male resembles her, so that he is coloured in a mud1 less gaudy and contrasted manner than the males of the previous species. In the eleventh and twelfth species* the females depart from the type of colouring wbid1 s See also Mr. Bates’ paper in 1 Proc. Ent. Soc. of Philadelpl*1^ 1S05, p. 206. Also Mr. Wallace on the same subject, in regal'1! Diadema, in 1 Transact. Entomolog. Soc. of London,’ 1&69, p. 27S. Chap. XI. BUTTERFLIES AND MOTHS. 389 is usual with their sex in this genus, for they are gaily decorated in nearly the same manner as the males, but in a somewhat less degree. Hence in these two species the bright colours of the males seem to have been trans- ferred to the females; whilst the male of the tenth species has either retained or recovered the plain colours of the female as well as of the parent-form of the genus ; the two sexes being thus rendered in both cases, though in an opposite manner, nearly alike. 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 through- out the genus retain the same general style of colouring, so that they commonly resemble each other much more closely than they resemble their own proper males. In the genus Papilio, all the species of the iEneas group are remarkable for their conspicuous and strongly contrasted colours, and they illustrate the frequent ten- dency to gradation in the amount of difference between the sexes. In a few species, for instance in P. ascanius, the males and females are alike ; in others the males are a little or very much more superbly coloured than the females. The genus Junonia allied to our Yanessse offers a nearly parallel case, for although the sexes of most of the species resemble each other and are desti- tute of rich colours, yet in certain species, as in J. oenone, the male is rather more brightly 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 Theche, in which both sexes 390 SEXUAL SELECTION. Part II* are nearly alike and wonderfully splendid ; in another, 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 butter- flies of the genus Lycmna, illustrate the various differ- ences in colour between the sexes, almost as well, though not in so striking a manner, as the above exotic genera. In Lycmna agestis both sexes have wings of a brown colour, bordered with small ocellated orange spots, and are consequently alike. In L. cegon the wings of the male are of a fine blue, bordered with black; whilst the wings of the female are brown, with a similar border, and closely resemble those of L. agestis- Lastly, in L. anon both sexes are of a bine colour and nearly alike, though in the female the edges of the wings are rather duskier, with the black spots plainer; and in a bright blue Indian species both sexes are still more closely alike. I have given the foregoing cases in some detail in order to shew, in the first place, that w hen the sexes ot butterflies differ, the male as a general rule is the most beautiful, and departs most from the usual type of colour' ing 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 exceptional cases, however, to which I shall here- after allude, the females are coloured more splendidly than the males. In the second place these cases 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 dif- ference that it was long before the two were placed by entomologists in the same genus. In the third place, we have seen that w'hen the sexes nearly resemble each other, this apparently may be due either to the Chap. XI. BUTTERFLIES AND MOTHS. 391 male having transferred, his colours to the female, or to the male having retained, or perhaps reco- vered, the primordial colours of the genus to which the species belongs. It also deserves notice that in those groups in which the sexes present any difference of colour, the females usually resemble the males to a cer- tain extent, so that when the males are beautiful to an extraordinary degree, the females almost invariably ex- hibit some degree of beauty. From the numerous 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 conclude that the causes, whatever they may be, which have determined the brilliant colouring of the males alone of some species, and ol both sexes in a moie or less equal degree of other species, have generally been the same. 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 4 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 when brilliantly-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 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 4 ‘ The Naturalist on the Amazons,’ vol. i. 1863, p. 19. 392 SEXUAL SELECTION. Pakt II. as we can judge, either for protection or as an attraction between the sexes. With many species of butterflies the upper surfaces of the wings are obscurely coloured, and this in all probability leads to their escaping ob- servation and danger. But butterflies when at rest would bo particularly liable to be attacked by their enemies; and almost all the kinds when resting raise their wings vertically over their backs, so that the lower sides alone are exposed to view. Hence it is this side which in many cases is obviously coloured so as to imitate the surfaces on which these insects commonly rest. Dr. Rossler, I believe, first noticed the similarity of the closed wings of certain Van ess* and other butter- flies to the bark of trees. Many analogous and striking facts could be given. The most interesting one is that recorded by Mr. Wallace5 of a common Indian and Sumatran butterfly (Kallima), which disappears like magic when it settles in a bush ; for it hides its head and antennae between its closed wings, and these in form, colour, and veining cannot be distinguished from a withered leaf together with the footstalk. In some other cases the lower surfaces of the wings are brilliantly coloured, and yet are protective ; thus in Thecla rubi the wings when closed are of an emerald green and re- semble the young leaves of the bramble, on which this butterfly in the spring may often be seen seated. Although the obscure tints of the upper or under surface of many butterflies no doubt serve to conceal them, yet we cannot possibly extend this view to the brilliant and conspicuous colours of many kinds, such as our admiral and peacock Vanessas, our white Sec the interesting article in the < Westminster Review,’ Julv, 1867, p. 10. A woodcut of the Kallima is given by Mr. Wallace in Hard- wieke’s ‘ Science Gossip,’ Sept. 1867, p. 196. Cjiap. XI. BUTTERFLIES AND MOTHS. 393 cabbage-butterflies (Pieris), or the great swallow-tail Papilio which haunts the open fens — for these butter- flies are thus rendered risible to every living creature. With these species both sexes are alike ; but iu the common brimstone butterfly (Goneptcryx rhamni ), the male is of an intense yellow, whilst the female is much paler; and in the orange-tip ( Anthocharis ccirdamines) the males alone have the bright orange tips to their wines. In these cases the males and females are equally conspicuous, and it is not credible that their difference in colour stands in any relation to ordinary protection. Nevertheless it is possible that the con- spicuous colours of many species may be in an indirect manner beneficial, as will hereafter be explained, by leading their enemies at once to recognise them as unpalatable. Even in this case it does not certainly follow that their bright colours and beautiful patterns were acquired for this special purpose. In some other remarkable cases, beauty has been gained for the sake of protection, 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. The female of our orange-tip buttterfly, above re- ferred to, and of an American species ( Anth . genutia) probably shew us, as Mr. Walsh has remarked to me, 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. We may infer here, as in several previous cases, that it is the males of Anth. cardamines and genutia which have departed from the usual type of colouring of their genus. In the Anth. sara from California, the orange-tips have become partially developed in the female ; for her wings are tipped with reddish-orange, but paler than in the 394 SEXUAL SELECTIONS Part II. male, and slightly different in some other respects. In an allied Indian form, the Iphias glaueippe, the orange- tips are fully developed in both sexes. In this Iphias the under surface of the wings marvellously resembles, as pointed out to me by Mr. A. Butler, a pale-coloured leaf ; and in our English orange-tip, the under surface resembles the flower-head of the wild parsley, on which it may be seen going to rest at night.6 The same reasoning power 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, especially when this character is confined to the maies, with bright orange for the same purpose. Turning now to Moths : most of these rest motion- less with their wings depressed during the whole or greater part of the day ; and the upper surfaces of their wings are often shaded and coloured in an admirable manner, as Mr. Wallace has remarked, for escaping detection. TV itli most of the Bombycidce and Noc- tuidse,1 when at rest, the front-wings overlap and conceal the hind-wings; so that the latter might be brightly coloured without much risk ; and they are thus coloured in many species of both families. During the act of flight, moths would often be able to escape from their enemies ; nevertheless, as the liind-wings are then fully exposed to view, their bright colours must generally have been acquired at the cost of some little risk. But the following fact shews us how cautious we ought to be in drawing conclu- sions on this head. The common yellow under-wing8 0 See the interesting observations by Mr. T. W. Wood, ‘ The Stu- dent,’ Sept. 1 868, p. 81. 7 Mr- Wallace in ‘Hardwicke’s Science Gossip,’ Sept. 1867, p. 193- Chap. XI. BUTTERFLIES AND MOTHS. 395 (Triphaena) 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 tlie body. For instance, Mr. Weir turned into his aviary a vigorous specimen of Triphaena 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 experi- ment, in the open air, with a T. fimbria and swallow ; but the large size of this moth probably interfered with its capture.8 9 We are thus reminded of a state- ment made by Mr. Wallace,8 namely, that in the Bra- zilian forests and Malayan islands, many common and highly-decorated butterflies are weak flyers, though fur- nished with a broad expanse of wings ; 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 pro- “ portion 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 indirectly beneficial. Display. — The bright colours of buttci flies and of some moths are specially arranged for display, whether or not they serve in addition as a protection. Bright 8 See also, on this subject, Mr. Weir’s paper in ‘ Transact. Ent. Soc.’ 1869. p. 23. 9 ‘ Westminster Review,’ July, 18(37, p. 16. 396 SEXUAL SELECTION. Part II. colours would not be visible during the nigbt; and there can be no doubt that moths, taken as a body, are much less gaily decorated than butterflies, all of which are diurnal in their habits. But the moths in certain families, such as the Zygtenidae, various Sphingidas, Uraniidae, some Arctiidas and Saturnikke, fly about during the day or early evening, and many of these are extremely beautiful, being far more brightly coloured than the strictly nocturnal kinds. A few exceptional cases, however, of brightly-coloured noc- turnal species have been recorded.10 There is evidence of another kind in regard to display. Butterflies, as before remarked, elevate their wings when at rest, and whilst basking in the sunshine often alternately raise anti depress them, thus exposing to full view both surfaces; and although the lower surface is often coloured in an obscure manner as a protection, yet in many species it is as highly coloured as the upper surface, and sometimes in a very different man- ner. In some tropical species the lower surface is even more brilliantly coloured than the upper.11 In one English fritillary, the Argynnis agluia, the lower sur- face alone is ornamented with shining silver discs. Nevertheless, as a general rule, the upper surface, which is probably the most fully exposed, is coloured more brightly and in a more diversified manner than the lower. Hence the lower surface generally affords 10 For instance, Lithosia ; but Prof. Westwood (‘ Modern Class, of Insects,’ vol. ii. p. 390) seems surprised at this case. On the relative colour’s of diurnal and nocturnal Lepidoptera, see ibid. p. 333 and 392 ; also Harris, ‘Treatise on the Insects of New England,’ J842, p. 315. 11 Such differences between the upper and lower surfaces of the wings of several species of Papilio, may be seen in the beautiful plates to Mr. Wallace’s Memoir on the Papilionidse of the Malayan Region, in ‘ transact. Linn. Soc.’ vol. xxv. part i. 1865. Chap. XI. BUTTERFLIES AND MOTHS. 397 to entomologists the most useful character for detecting the affinities of the various species. Now if we turn to the enormous group of moths, which do not habitually expose to full view the under surface of their wings, this side is very rarely, as I hear from Mr. Stainton, coloured more brightly than the upper side, or even with equal brightness. Some ex- ceptions to the rule, either real or apparent, must be noticed, as that of Hypopyra, speci lied by Mr. W orrnabl.12 Mr. E. Trimen informs me that in Guenee’s great work, three moths are figured, in which the under surface is much the most 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-white. 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 wino-s in certain other Geometrae 13 and quadrifid Nocture 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 considerable “time,” and thus exposing to view the under surface. Other species when settled on the ground or herbage have the habit of now and then suddenly and slightly lifting up their wings. Hence the lower suiface of the wings being more brightly-coloured than the upper sur- » ‘Proc. Ent. Soc.’ Mai ch 2nd, 1808. 13 See also an account of the S. American genus Erateina (one of the Geometrae) in fc Transact. Ent. Soc. new series, vol. v. pi. xv. and xvi. 398 SEXUAL SELECTION. Pari II. face in certain moths is not so anomalous a circum- stance as it at first appears. The Saturniidse 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. Wood14 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 than of nocturnal Lepidoptera.” It is a singular fact that no British moths, nor as far as I can discover hardly any foreign species, which are brilliantly coloured, differ much in colour according to sex; though this is the case with many brilliant but- terflies. The male, however, of one American moth, the Saturnia Io, is described as having its fore-wings deep yellow, curiously marked with purplish-red spots ; whilst the wings of the female arc purple-brown, marked with grey lines,15 The British moths which differ sexually in colour are all brown, or various tints of dull yellow, or nearly white. In several species the males are much darker than the females,16 and these belong to groups which generally fly about during the afternoon. On the other hand, in many genera, as Mr. Stainton informs me, 11 ‘Proc. Ent. Soc. of London,’ July 6, 1868, p. xxvii. 16 Harris, 1 Treatise,’ &e., edited by Flint, 1802, p. 395. “ Tor instance, I observe in my son’s cabinet that the males are darker than the females in the Lasiocampa querc-us, (Jdonestis potatorum Bypogymna ditpar, Dusyehim pttdibuuda, and Cycnia mendica. In this latter species the difference in colour between the two sexes is strong)' marked ; and Mr. Wallace informs mo that we here have, as he believes. an instance of protective mimiekry confined to one sex, as will hereafter be more fully explained. The white female of the Cycnia resembles the very common Spihsoma meniUrasti, both sexes of which are white : and Mr. Stainton observed lhat this latter moth was rejected with utter disgust by a whole brood of young turkeys, which were fond of eating other moths ; so that if the Cycnia was commonly mistaken by British birds for the Spilosoma, it would escape being devoured, aud its white deceptive colour would thus be highly beneficial. Chap. XI. BUTTERFLIES AND MOTHS. 399 the males have the hind-wings whiter than those of the female — of which fact Agrotis exclamationis offers a good instance. The males are thus rendered more conspicuous than the females, whilst hying about in the dusk. In the Ghost Moth ( Eepialus humuli ) the difference is more strongly marked; the males being white and the females yellow with darker markings. It is difficult to conjecture what tlie meaning can be of these differences between the sexes in the shades of darkness or lightness; but wo can hardly suppose that they are the result of mere variability with sexually- limited inheritance, independently of any benefit thus derived. From the foregoing statements 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 suppose that the females generally prefer, or are most excited by the more brilliant males ; for on any other supposition the males would be ornamented, as for as we can see, for no purpose. We know that ants and certain lamellicorn beetles are capable of feeling an attachment for each other, and that ants recognise their fellows after an interval of several months. Hence there is no abstract improbability in the Lepidoptera, which pro- bably stand nearly or quite as high in the scale as these insects, having sufficient mental capacity to admire bright colours. They certainly discover flowers by colour, and, as I have elsewhere shewn, the plants which are fertilised exclusively by the wind never have a conspicuously-coloured corolla, l'he Humming-bird Sphinx may often be seen to swoop down from a distance on a bunch of flowers in the midst of green foliage ; 400 SEXUAL SELECTION. Part II. and I have been assured by a friend, that these moths repeatedly visited flowers painted on the walls of a room in tire South of France, The common white butterfly, as 1 hear from Mr. Doubleday, often flies down to a bit of paper on the ground, no doubt mistaking it for one of its own species. Mr. Collingwood17 in speaking of the difficulty of collecting certain butterflies in the Malay Archipelago, states that “a dead specimen pinned upon “a conspicuous twig will often arrest an insect of the “ same species in its headlong flight, and bring it down “ within easy reach of the net, especially if it be of the “opposite sex.” The courtship of butterflies is a prolonged affair. The males sometimes fight together in rivalry ; and many may bo seen pursuing or crowding round the same female. If, then, the females do not prefer one male to another, the pairing must be left to mere chance, and this does not appear to me a probable event. If, on the other hand, the females habitually, or even occasionally, prefer the more beautiful males, the colours of the latter will have been rendered brighter by degrees, and will have been transmitted to both sexes or to one sex, according to which law of inheritance prevailed. The process of sexual selection will have been much facili' tated, if the conclusions arrived at from various kinds of evidence in the supplement to the ninth chapter can be trusted ; namely that the males of many Lepidoptera, at least in the imago state, greatly exceed in number the females. Some facts, however, are opposed to the belief that female butterflies prefer the more beautiful males ; thus, as I have been assured by several observers, fresh females may frequently be seen paired with battered, faded or " ‘ Rambles of a Naturalist in the Chinese Seas,’ 1S68, p. 182, Chap. XI. BUTTERFLIES AND MOTHS. 401 dingy males ; but this is a circumstance which could hardly fail often to follow from the males emerging from their cocoons earlier than the females. With moths of the family of the Bombycidae, the sexes pair imme- diately after assuming the imago state ; for they cannot feed, owing to the rudimentary condition of their mouths. The females, as several entomologists have remarked to me, lie in an almost torpid state, and appear not to evince the least choice in regard to their partners. This is the case with the common silk-moth (B. mori), as I have been told by some continental and English breeders. Dr. Wallace, who has had such immense experience in breeding Bombyx cynthia, is convinced that the females evince no choice or preference. He has kept above bOO of these moths living together, and has often found the most vigorous females mated with stunted males. The reverse apparently seldom occurs ; for, as he believes, the more vigorous males pass over the weakly females, being attracted by those endowed with most vitality. Although we have been indirectly in- duced to believe that the females of many species prefer the more beautiful males, I have no reason to suspect, either with moths or butterflies, that the males are attracted by the beauty of the females. If the more beautiful females had been continually preferred, it is almost certain, from the colours of butterflies being so frequently transmitted to one sex alone, that the females would often have been rendered more beautiful than their male partners. But this does not occur except in a few instances ; and these can be explained, as we shall presently see, on the principle of mimickry and protection. As sexual selection primarily depends on variability, a few words must be added on this subject. In respect VOL. i. 2d 402 SEXUAL SELECTION. Pact II. to colour there is no difficulty, as any number of highly variable Lepidoptera could be named. One good in- stance will suffice. Mi-. Bates shewed me a whole series of specimens of Papilio sesostris and childrens; in the latter the males varied much iu the extent of the beau- tifully enamelled green patch on the fore-wings, and in the size of the white mark, as well as of the splendid crimson stripe on the hind-wings; so that there was a great contrast between the most and least gaudy males. The male of Papilio sesostris, though a beautiful insect, is much less so than P. children re. It likewise varies a little in the size of the green patch on the fore- wings, and in the occasional appearance of a small crimson stripe on the hind-wings, borrowed, as it would seem, from its own female ; for the females of this and of many other species in the -Tineas group possess this crimson stripe. Hence between the brightest specimens of P. sesostris and the least bright of P. children se, there was hut a small interval ; and it was evident that as far as mere variability is concerned, there would be no difficulty in permanently increasing by means of selec- tion the beauty of either species. The variability hero almost confined to the male sex; but Mr. "Wallace and Mr. Bates have shewn that the females of some other species are extremely variable, the males being nearly constant. As I have before mentioned the Ghost Moth ( Hepialus humuli ) as one of the best instances i11 Britain of a difference in colour between the sexes of moths, it may he worth adding19 that in the Shetland 18 Wallace on the Papiliouid® of tlie Malayan Region, in ‘ Transact. Linn. Soc.’ vol. xxv. 1805, p. 8, 3G. A striking case of a rare variety, strictly intermediate between two other well-marked female varieties, is given by Mr. Wallace. See also Mr. Bates, in ‘Ibne. Entomolog' Soc.’ Nov. 19th, 1SG6, p. xl. 19 Mr. E. MacLacldan, ‘ Transact. Ent. Soc.’ vol. ii. part Gtk, or series, 18GG, p, 459. Chap. XI. BUTTERFLIES AND MOTHS. 403 Islands, males are frequently found which closely resemble the females. In a future chapter I shall have occasion to shew that the beautiful eye-like spots or ocelli, so common on the wings of many Lepidoptera, are eminently variable. On the whole, although many serious objections may be urged, it seems probable that most of the species of Lepidoptera which are brilliantly coloured, owe their colours to sexual selection, excepting in certain cases, presently to be mentioned, in which conspicuous colours are beneficial as a protection. From the ardour of the male throughout the animal kingdom, he is generally willing to accept any female ; and it is the female which usually exerts a choice. Hence if sexual selection has here acted, the male, when the sexes differ, ought to be the most brilliantly coloured ; and this undoubtedly is the ordinary rule. When the sexes are brilliantly co- loured and resemble each other, the characters acquired by the males appear to have been transmitted to both sexes. But will this explanation of the similarity and dissimilarity in colour between the sexes suffice? The males and females of the same species of butterfly are known20 in several cases to inhabit different stations, the former commonly basking in the sunshine, the latter haunting gloomy forests. It is therefore possible that different conditions of life may have acted directly on the two sexes ; but this is not probable,21 as in the adult state they are exposed during a very short period to different conditions ; and the larval of both are ex- posed to the same conditions. Mr. Wallace believes so H. W. Bates, ‘The Naturalist on tlie Amazons,’ vol. ii. 18G3, p. 228. A. R. Wallace, in ‘ Transact. Linn. .Soc.’ vol. xxv. 18G5, p. 10. 21 On this whole subject see ‘The Variation of Animals and Plants under Domestication,’ vol. ii. 1868, chap, xxiii. 2 d 2 404 SEXUAL SELECTIOX. Fart II- that the less brilliant colours of the female have been specially gained in all or almost all cases for the sake of protection. On the contrary it seems to me more probable that the males alone, in the large majority of cases, have acquired their bright colours through sexual selection, the females having been but little modified. Consequently the females of distinct but allied species ought to resemble each other much more closely than do the males of the same species ; and this is the general rule. The females thus approximately show us the pri- mordial colouring of the parent-species of the group to which they belong. They have, however, almost always been modified to a certain extent by some of the succes- sive steps of variation, through the accumulation of which the males were rendered beautiful, having been transferred to them. The nudes and females of allied though distinct species will also generally have been exposed during their prolonged larval state to different conditions, and may have been thus indirectly affected ; though with the males any slight change of colour thus caused will often have been completely masked by the brilliant tints gaiued through sexual selection. When we treat of Birds, I shall have to discuss the whole question whether the differences in colour between the males and females have been in part specially gained by the latter as a protection ; so that I will here only give unavoidable details. In all eases when the more common form of equal inheritance by both sexes has prevailed, the selection of bright-coloured males would tend to make the females bright-coloured ; and the selection of dull-coloured fe- males would tend to make the males dull. If both pro- cesses were carried on simultaneously, they would tend to neutralise each other. As far as I can see, it would he extremely difficult to change through selection the Chap. XI. BUTTERFLIES AXD MOTHS. 405 one form of inheritance into the other. But hv the selection of successive variations, which were from the first sexually limited in their transmission, 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 latter manner female butterflies and moths may, as I fully admit, have been rendered inconspicuous for the sake of protection, and widely different from their males. Mr. Wallace 33 has argued with much force in favour of his view that when the sexes differ, the female has been specially modified for the sake of protection ; and that this has been effected by one form of inheritance, namely, the transmission of characters to both sexes, having been changed through the agency of natural selection into the other form, namely, transmission to one sex. I was at first, strongly inclined to accept this view ; but the more I have studied the various classes throughout the animal kingdom, the less probable it has appeared. Mr. Wallace urges that both sexes of the Keliconidm, Danaidm, Acra idm are equally brilliant because both are protected from the attacks of birds and other enemies, by their offensive odour ; but that iu other groups, which do not possess this immunity, the females have been rendered inconspicuous, from having more need of protection than the males, ffhis supposed difference in the “ need of protection by the “ two sexes ” is rather deceptive, and requires some discussion. It is obvious that brightly-coloured indi- viduals, whether males or females, would equally attract, and obscurely-coloured individuals equally escape, the 22 A. E. Wallace, in ‘ The Journal of Travel,’ vol. i, 1868, p. 88. 1 Westminster Review,’ July, 1867, p. 37. See also Messrs. Wallace and Bates iu ‘ Proc. Ent. Soc.’ Nov. 19th, 1866, p. xxxix. 406 SEXUAL SELECTION. Part II. attention of their enemies. But we are concerned with the effects of the destruction or preservation of certain individuals of either sex, on the character of the race. With insects, after the male has fertilised the female, and after the latter has laid her eggs, the greater or less immunity from danger of either sex could not possibly have any effect on the offspring. Before the sexes have performed their proper functions, if they existed in equal numbers and if they strictly paired (all other circumstances being the same), the preservation of the males and females would be equally important for the existence of the species and for the character of the offspring. But with most animals, as is known to he the case with the domestic silk-moth, the male can fertilise two or three females ; so that the destruction of the males would not he so injurious to the species as that of the females. On the other hand, Dr. Wallace believes that with moths the progeny from a second or third fertilisation is apt to be weakly, and therefore would not have so good chance of surviving. When the males exist in much greater numbers than the females, no doubt many males might be destroyed with impunity to the species ; but I cannot see that the results of ordinary selection for the sake of protection would he inlluenced by the sexes existing in unequal numbers ; for the same proportion of the more con- spicuous individuals, whether males or females, would probably be destroyed. If indeed the males presented a greater range of variation in colour, the result would he different ; but we need not here follow out such com- plex details. On the whole I cannot perceive that an inequality in the numbers of the two sexes would in- fluence in any marked manner the effects of ordinary selection on the character of the offspring. Bemale Lepidoptera require, as Mr. Wallace insists Chap. XI. BUTTERFLIES AND MOTHS. 407 some days to deposit their fertilised ova and to search for a proper place; during this period (whilst the life of the male was of no importance) the brighter-coloured females would be exposed to danger and would be liable to be destroyed. The duller-coloured females on the other hand would survive, aud thus would in- fluence, it might be thought, in a marked manner the character of the species, — either of both sexes or of one sex, according to which form of inheritance pre- vailed. But it must not be forgotten that the males emerge from the cocoon-state some days before the females, and during this period, whilst the unborn females were safe, the brighter-coloured males would be exposed to danger ; so that ultimately both sexes would probably be exposed during a nearly equal length oi time to danger, and the elimination of conspicuous colours would not be much more effective in the one than the other sex. It is a more important consideration that female Lepidoptera, as Mr. Wallace remarks, and as is known to every collector, are generally slower flyers than the males. Consequently the latter, if exposed to greater danger from being conspicuously coloured, might be able to escape from their enemies, whilst the similarlv-coloured loin ales would he destroyed , and thus the females would have the most influence in modi- fying the colour of their progeny. There is one other consideration: bright colours, as far as sexual selection is concerned, are commonly of no service to the iemales ; so that if the latter varied in brightness, and the variations were sexually limited in their transmission, it would depend on meio chance whether the females had their bright colours increased ; and this would tend throughout the Order to diminish the number of species with brightly-coloured females 408 SEXUAL SELECTION. Part II. in comparison with the species having brightly-coloured males. On the other hand, as bright colours are sup- posed to be highly serviceable to the males in their love-struggles, the brighter males (as we shall see in the chapter on Birds) although exposed to rather greater danger, would on an average procreate a greater number of offspring than the duller males. In this case, il the variations were limited in their transmission to the male sex, the males alone would be rendered more brilliantly coloured; but if the variations were not thus limited, the preservation and augmentation of such variations would depend on whether more evil was caused to the species by the females being rendered conspicuous, than good to the males by certain indivi- duals being successful over their rivals. As there can hardly be a doubt that both sexes of many butterflies and moths have been rendered dull- coloured for the sake ot protection, so it may have been with the females alone of some species in which successive variations towards dullness first appeared in the female sex and were from the first limited in their transmission to the same sex. If not thus limited, both sexes would become dull-coloured. We shall immediately see, w'hen we treat of mimickry, that the females alone of certain butterflies have been ren- dered extremely beautiful for the sake of protection, without any of the successive protective variations having been transferred to the male, to whom they could not possibly have been in the least degree injuri- ous, and therefore could not have been eliminated through natural selection. Whether in each particular species, in which the sexes differ in colour, it is the female which has been specially modified for the sake of protection ; or whether it is the male which has been specially modified for the sake of sexual attraction, the Chap. XI. BUTTERFLIES AND MOTHS. 409 female having retained her primordial colouring only slightly changed through the agencies before alluded to; or whether again both sexes have been modified, the female for protection and the male for sexual attrac- tion, can only bo definitely decided when we know the life-history of each species. Without distinct evidence, I am unwilling to admit that a double process of selection has long been going on with a multitude of species, — the males having been rendered more brilliant by beating their rivals ; and the females more dull-coloured by having escaped from their enemies. We may take as an instance the common brim- stone butterfly (G-onepteryx), which appears early in the spring before any other kind. The male of this species is of a far more intense yellow than the female, though she is almost equally conspicuous ; and in this case it does not seem probable that she specially acquired her pale tints as a protection, though it is probable that the male acquired his bright colours as a sexual attraction. The female of Anthocharis cardamines does not possess the beautiful orange tips to her wings with which the male is ornamented ; consequently she closely resembles the white butterflies (Pieris) so common in our wardens ; but we have no evidence that this resem- blance is beneficial. On the contrary, as she resembles both sexes of several species of the same genus inhabit- ing various quarters of the world, it is more probable that she has simply retained to a large extent her primordial colours. _ Various facts support the conclusion that with the greater number of brilliantly-coloured Lepidoptera, it is the male which has been modified ; the two sexes having come to differ from each other, or to resemble each other, according to which form of inheritance has prevailed. Inheritance is governed by so many un- 410 SEXUAL SELECTION. Part It known laws or conditions, that they seem to ns to he most capricious in their action ; 23 and we can so far understand how it is that with closely-allied species the sexes of some differ to an astonishing degree, whilst the sexes ot others are identical in colour. As the successive steps in the process of variation are neces- sarily all transmitted 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 no difference at all between the sexes of the species within the same group. These cases of gradation are much too common to favour the supposition that we here see females actually undergoing the process of transition and losing their brightness for the sake of protection ; for we have every reason to conclude that at any one time the greater number of species are in a fixed condition. With respect to the differences between the females of the species in the same genus or family, we can perceive that they depend, at least in part, on the females partaking ot the colours of their respective males. rlhis is well illustrated in those groups in which the males are ornamented to an extraordinary degree j lor the females in these groups generally partake to a certain extent ot the splendour of their male partners. Lastly, we continually find, as already remarked, that the females of almost all the species in the same genus, or even family, resemble each other much more closely in colour than do the males ; and this indicates that the males have undergone a greater amount of modifi' cation than the females. 23 The Variation of Animals and Plants under Domestication, vol. ii. chap. xii. p. 17. Chap. XI. BUTTERFLIES AND MOTHS. 411 Mimichry.— This principle was first made clear in an admirable paper by Mr. Bates,24 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 Heli- coni dm so closely in every stripe and shade ot colour that they could not be distinguished except by an experienced entomologist. As the Heliconklm 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 Heliconidse the imitated. Mr. Bates further observed- that the imitating species are comparatively rare, whilst the imitated swarm in large numbers ; the two sets living mingled together. From the fact of the Heli- couidie being conspicuous aud beautiful insects, vet so numerous in individuals and species, he concluded that they must be protected from the attacks ot birds by some secretion or odour; and this hypothesis has now been confirmed by a considerable body of curious evidence.25 From these considerations Mr. Bates in- ferred that the butterflies which imitate the protected species had acquired their present marvellously decep- tive 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 ol the imi- tated, but only of tho imitating butterflies. We must account for the colours of the former m the same general manner, as in the cases previously discussed m this chapter. Since the publication of Mr. Bates’ paper, similar and equally striking facts have been observed =1 1 Transact. Linn. Soc.’ vol. xxiii. 18G2, p. 495. 25 < Proc. Ent. Soc.’ Dec. 3rd, 1866, p. xlv. 412 SEXUAL SELECTION. Part II. by Mi. Wallace26 in the Malayan region, and by Mr. Trimen in South Africa. As some writers 27 have felt much difficulty in under- standing how the first steps in the process of mimickrv could have been effected through natural selection, it may be well to remark that the process probably has never commenced with forms widely dissimilar in colour. l>ut with two species moderately like each other, the closest resemblance if beneficial to either form could readily be thus gained ; and if the imitated form was subsequently and gradually modified through sexual selection or any other means, the imitating form would be led along the same track, and thus be modified to almost any extent, so that it might ultimately assume an appearance or colouring wholly unlike that of the other members of the group to which it belonged. As extremely slight variations in colour would notin many cases suffice to render a species so like another pro- tected species as to lead to its preservation, it should 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; but under this point of view Mr. Bates’ original paper on mimickry, as well as Mr. Wallace’s papers, should be consulted. In the foregoing cases both sexes of the imitating species resemble the imitated; but occasionally the 26 ‘Transact. Linn. Soo.’ vol. xxv. 1SG5, p. 1; also ‘ Transact. Ent. Soc. vol. iv. (3rd series), 1807, p. 301. See an ingenious article entitled, “Difficulties oftlie Theory of Natural Selection,” in the * Month/ 18G9. The writer strangely sup- poses that 1 attribute the variations in colour of the Lepidoptera, by which certain species belonging to distinct families have come to resemble others, to reversion to a common progenitor ; but there is no more reason to attribute these variations to reversion than in the oase of any ordinary variation. Chap. XI. BUTTERFLIES AND MOTHS. 413 female alone mocks a brilliantly-coloured and protected species inhabiting the same district. Consequently the female differs in colour from her own male, and, which is a rare and anomalous circumstance, is the more brightly-coloured of the two. In all the few species of Pieridae, in which the female is more conspicuously coloured than the male, she imitates, as I am informed by Mr. Wallace, some protected species inhabiting the same region. The female of Diadema anomala is rich purple-brown with almost the whole surface glossed with satiny blue, and she closely imitates the Euplcea rnida- mus, “one of the commonest butterflies of the East;” whilst the male is bronzy or olive-brown, with only a slight blue gloss on the outer parts of the wings.28 Both sexes of this Diadema and of I). Mina follow the same habits of life, so that the differences in colour between the sexes cannot be accounted for by exposure to different conditions;29 even if this explanation were admissible in other instances."0 The above cases of female butterflies which are more brightly-coloured than the males, shew us, firstly, that variations have arisen in a state of nature in the female sex, and have been transmitted exclusively, or almost ex- clusively, to the same sex ; and, secondly, that this form of inheritance has not been determined through natural selection. For if we assume that the females, before they became brightly coloured in imitation of some pro- tected kind, were exposed during each season for a longer period to danger than the males ; or if we assume that 28 Wallace, 14 Notes on Eastern Butterflies, Transact. Ent. feoc. 1869, p. 287. 23 Wallace, in ‘Westminster Beview,’ July, 1867, p. 37; and in ‘ Journal of Travel and Nat. Hist. vol. i. 1868, p. SS. 30 See remarks by Messrs. Bates and Wallace, in ‘ Proc. Ent. Soc.’ Nov. 19, 1866, p. xxxix. 414 SEXUAL SELECTIOX. Part II. they could not escape so swiftly from their enemies, we can understand how they alone might originally have acquired through natural selection and sexually- limited inheritance their present protective colours. But except on the principle of these variations having been transmitted exclusively to the female offspring, we cannot understand why the males should have re- mained dull-coloured ; for it would surely not have been in any way injurious to each individual male to have partaken by inheritance of the protective colours of the female, and thus to have had a better chance of escaping destruction. In a group in which brilliant colours are so common as with butterflies, it cannot be supposed that the males have been kept dull-coloured through sexual selection by the females rejecting the individuals which were rendered as beautiful as them- selves. We may, therefore, conclude that in these cases inheritance by one sex is not due to the modification through natural selection of a tendency to equal inherit- ance by both, sexes. It may be well here to give an analogous case in another Order, of characters acquired only by the female, though not in the least injurious, as far as we can judge, to the male. Amongst the Phasmidse, or spectre-insects, Mr. Wallace states that “it is often the females alone “ that so strikingly resemble leaves, while the males show “only a rude approximation.” Now, whatever may be the habits of these insects, it is highly improbable that it could be disadvantageous to the males to escape de- tection by resembling leaves.'51 Hence we may conclude 31 See Mr. Wallace in ‘Westminster lie view,' July, 1867, p. 11 an>l 37. The male of no butterfly, as Mr. Wallace informs me, is known to differ in colour, as a protection, from the female ; and he asks me how I can explain this fact on the principle that one sex alone has varied and has transmitted its variations exclusively to the same sex, without Chap. XI. BUTTEKFLIES AND MOTHS. 415 that the females alone in this latter as in the previous cases originally varied in certain characters ; these cha- racters having been preserved and augmented through ordinary selection lor the sake of protection and from the first transmitted to the female offspring alone. Bright Colours of Caterpillars. — Whilst reflecting on the beauty of many butterflies, it occurred to me that some caterpillars 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 larvae could be in some manner 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 the aid of select ion io clieok the variations being inherited by the other sex. No doubt if it could be shewn that the females ol' very many species had been rendered beautiful through protective niimickry, hut that this has never occurred with tlie males, it would be a serious difficulty. But the number of eases os yet known hardly suffices for a fair judgment. We can see that the males, from having the power of flying more swiftly, and thus escaping danger, would not be so likely as the females to have had fheir colours modified for the sake of protec- tion; but this would not in the least have interfered with their receiving protective colours through inheritance from the females. In the second place, it is probable tbat sexual selection would actually tend to picveut abeautiful male from becoming obscure, for the less brilliant. individuals would he less attractive to the females. Supposing that the beauty of the male of any species had been mainly acquired through sexual selection, yet if this beauty likewise served as a protection, the acquisi- tion would have been aided by' natural selection. But it would be quite beyond our power to distinguish between the two processes ot sexual and ordinary selection. Hence it is not likely that we should he able to adduce eases of the males having been rendered brilliant exclusively through protective niimickry, though this is comparatively easy with the females, which have rarely or never been rendered beau- tiful, as far as we can judge, fur the sake ol sexual attraction, although they have often received beauty through inheritance from their male parents. 416 SEXUAL SELECTIOX. Part II. serve in any ordinary manner as a protection. As an instance of this, Mr. Bates informs me tiiat 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 ; it 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 man who passed by at the distance of many yards, and no doubt 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 curiously like the twigs of the trees on which they “ live.” 1 may add as another instance of protection, that there is a caterpillar of a moth, as I am informed by Mr. J. Mansel Weale, which lives on the mimosas in South Africa, and fabricates for itself a case, quite un- distinguishable from the surrounding thorns. From such considerations Mr. Wallace thought it probable that conspicuously-coloured caterpillars were protected by having a nauseous taste ; but as their skin is ex- tremely 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 Mr. W allace 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 bo highly advantageous to a caterpillar to be instantaneously and certainly recog- nised as unpalatable by all birds and other animals- Chap. XI. SUMMARY ON INSECTS. 417 Thus the most gaudy colours would be serviceable, and might have been gained by variation and the survival of the most easily-recognised individuals. This hypothesis appears at first sight very bold ; but when it was brought before the Entomological Society32 it was supported by various statements ; and Mr. J. Jenner Weir, who keeps a large number of birds in an aviary, has made, as he informs me, numerous trials, and finds no exception to the rule, that all caterpillars of nocturnal anil 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 invariably rejected, as were four conspicuously- coloured species. When the birds rejected a caterpillar, they plainly shewed, by shaking their heads and cleans- ing their beaks, that they wore disgusted by the taste.33 Three conspicuous kinds of caterpillars and moths were also given by Mr. A. Butler to some lizards and frogs, and were rejected ; though other kinds were eagerly eaten. Thus the probable truth of Mr. Wallace’s view is confirmed, namely, that certain caterpillars have been made conspicuous lor their own good, so as to lie easily recognised by their enemies, on nearly the same prin- ciple that certain poisons are coloured by druggists for the good of man. This view will, it is probable, be hereafter extended to many animals, which are coloured in a conspicuous manner. Summary and Concluding Hemarlts on Insects. — Looking back to the several Orders, we have seen that the sexes often differ in various characters, the meaning 32 * Proc. Entomolog. Soc.’ Dec. 3rd, 1866, p. xlv., and March 4th, 1S67, p. Ixxx. 33 See Mr. J. Jenner AVeir’s paper on insects and insectivorous birds, in 1 Transact. Ent. Soc.' 1869, p. 21 ; also Mr. Butler’s paper, ibid p. 27. VOL. I. ^ E 418 SEXUAL SELECTION. Part II. of which is not understood. The sexes, also, often differ in their organs of sense or locomotion, so that the males may quickly discover or reach the females, and still oftener in the males possessing diversified contrivances for retaining the females when found. But we are not here much concerned 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 hisrhly 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 probably it is that the males have not often been rendered larger and stronger than the females. On the contrary they are usually smaller, in order that they may be developed within a shorter time, so as to be ready in large numbers for the emergence of the females. In two families of the Homoptera the males alone possess, in an efficient state, organs which may be called vocal ; and in three families of the Orthoptera the males alone possess stridulating organs. In botli cases these organs are incessantly used during the breeding-season, not only for calling the females, but for charming or exciting them in rivalry with other males. No one who admits the agency of natural selection, will dispute that these musical instruments have been acquired through sexual selection. In four other Orders the members of one sex, or more commonly of both sexes, are provided until organs for producing various sounds, which apparently serve merely as call-notes. Even 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 Chap. XI. SUMMARY ON INSECTS. 419 through, sexual selection. It is instrutive to reflect on the wonderful diversity of the means for producing sound, possessed by the males alone or by Loth sexes in no less than six Orders, and which were possessed by at least one insect at an extremely remote geolo- gical epoch. We thus learn how effectual sexual selec- tion has been in leading to modifications of structure, which sometimes, as with the Homoptera, are of an im- portant nature. From the reasons assigned in the last chapter, it is probable that the great horns of the males of many lamellicorn, and some other beetles, have been ac- quired as ornaments. So perhaps it may bo with cer- tain other peculiarities confined to the male sex. From the small size of insects, we are apt to undervalue their appearance. If we could imagine a male Chalcosoma (fig. 15) with its polished, bronzed coat of mail, and vast complex 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 brilliantly coloured, it is probable that the two sexes have varied in a slightly different manner, with the variations transmitted to the same sex, without any benefit having been thus derived or evil suffered. When the male is brilliantly coloured and differs con- spicuously from the female, as with some dragon-flies and many butterflies, it is probable that he alone has been modified, and that be owes bis colours to sexual selection ; whilst the female has retained a primordial or very ancient type of colouring, slightly modified by the agencies before explained, and has therefore not been rendered obscure, at least in most cases, for the sake of protection. But the female alone has some- 2 E 2 420 SEXUAL SELECTION. Pakt II. times been coloured brilliantly 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 coloured for the sake of protection. So it is in some instances when both are brightly coloured, causing them to resemble surrounding objects such as flowers, or other protected species, or indirectly by giving notice to their enemies that they are of an unpalatable nature. In many other cases in which the sexes resemble each other and are brilliantly coloured, 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 both sexes. We arc more especially led to this conclusion whenever the same type of coloration prevails through- out a group, and we find that the males of some species differ widely in colour from the females, whilst both sexes of other species are quite alike, with intermediate gradations connecting these extreme states. In the same manner as bright colours have often been partially transferred Jfom the males to the females, so it has been with the extraordinary horns of many lamellicorn and some other beetles. So, asain, the vocal or instrumental 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 used for producing sound. It is also an interesting fact, as bearing on sexual selection, that the stridulating organs of certain male Orthoptera are not fully deve- loped until the last moult ; and that the colours of cer- tain male dragon-flies are not fully developed until some little time after their emergence from the pupal state, and when they are ready to breed. Chap. XI. SUMMARY ON INSECTS. 421 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 rare exceptions, is the most ornamented and departs most 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 habit- ually 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 contrivances 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. In the case of unions between distinct species, of which many instances have been recorded, the female must have been a consenting party. Judging from what we know of the perceptive powers and affections of various insects, there is no antecedent im- probability in sexual selection having come largely into action ; but we have as yet no direct evidence on this head, and some facts are opposed to the belief. Never- theless, 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 alone is decorated. If we admit that the females of the Homoptera and Orthoptera appreciate the musical tones emitted by their male partners, and that the various instruments for this purpose have been perfected through sexual selection, there is little improbability in the iemales ot other insects appreciating beauty in form or colour, and con- sequently in such characters having been thus gained 422 SEXUAL SELECTION. Part II. 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 extremely difficult to decide in how large a proportion of cases sexual selection has come into play. This is more especially difficult in those Orders, such as the Orthop- tera, Hymenoptera, and Coleoptera, in which the two sexes rarely ditfer much in colour ; for wre are thus cut off from our best evidence of some relation between the reproduction of the species and colour. 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 stridulatiug organs, and others ornamented with splendid metallic tints. Hence it seems probable that all these characters have been trained through O O the same means, namely sexual selection. When we treat of Birds, we shall see that they pre- sent 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 during 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 dis- play. 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 CriAP. XI. SUMMAKY ON INSECTS. 423 anomalous cases, the females are more beautiful than the males. We shall often find, in the same group of birds, every gradation from no difference between the sexes, to an extreme difference. In the latter case we shall see that the females, like female insects, often possess more or less plain traces of the characters which properly belong to the males. The analogy, indeed, in all these respects between birds and insects, is curiously close. "Whatever explanation applies to the one class probably applies to the other ; and this explanation, as wye shall hereafter attempt to shew, is almost certainly sexual selection. END OF VOL. I. PRINTED LONDON : WILLIAM CLOWES AND SONS, DUKE STREET, STAMFORD STREET, AND CHARING CROSS. TELEGRAPHIC AOORESS — BOOKMEN, LONDON, codes-UNICODE aH'1 / Telephone, CENTRAL, 1515. BOOKSELLERS BY AP pOlNf 9^0-77 l /p\ A 'M Oo Bridge ) rL'^.r c/c VB.C. CHEQUES CROSSED UOYDS'BANK, 222 STRAND, MONEY ORDERS PAYABLE AT S OUTH AM PTON SYSTRAN D,W.C. NETT. Ment to h.m.the king. bibliotheek ****** ?}> / ' \* ' * 0 % * — — — THE DESCENT OF MAN, AND SELECTION IN RELATION TO SEX. THE descent op man, AND SELECTION IN RELATION TO SEX. By CHARLES DARWIN, M.A., P.R.S., &c. IN TWO VOLUMES.— Vol. II. WITH ILLUSTRATIONS. SEVENTH THOUSAND. LONDON: J OHN MURRAY, ALBEMARLE STREET. 1871. [ The right of Translation is reserved .] BY THE SAME AUTHOR. ON THE ORIGIN OF SPECIES BY MEANS OF NATURAL SELECTION ; or, The Preservation of Favoured Races in the Struggle for Life. Filth Edition {Tenth Thousand), with Additions and Corrections. 1869, Murray. THE VARIATION OF ANIMALS AND PLANTS UNDER DOMESTICATION. In two vols. With Illustrations. 1868. Murray. ON THE VARIOUS CONTRIVANCES by which BRITISH AND FOREIGN ORCHIDS ARE FERTILISED BY INSECTS; and on the Good Effects of Crossing. With numerous Woodcuts. Murray, A NATURALIST’S VOYAGE ROUND THE WORLD; or, A Journal of Researches into tiif. Natural History and Geology of the Countries visited during the voyage of H.M.S. * Beagle,’ under the command of Captain Frrzllor, R.N. Eleventh Thousand. Murray. ON THE STRUCTURE AND DISTRIBUTION OF CORAL REEFS. Smith, Elder, & Co. GEOLOGICAL OBSERVATIONS ON VOLCANIC ISLANDS . Smith, Elder, & Co. GEOLOGICAL OBSERVATIONS ON SOUTH AMERICA. Smith, Elder, & Co. A MONOGRAPH OF THE CIREIPEDIA. With numerous Illustrations. 2 vols. 8vo, Hardwicke. ON THE MOVEMENTS AND HABITS OF CLIMBING PLANTS, With Woodcuts. Williams & Nougate. London: printed by william clowes and sons, stameord street, and charing cross. CONTENTS PART II. SEXUAL SELECTION — continued. CHAPTER XII. Secondary Sexual Characteks of Fishes, Amphibians, and Reptiles. Wishes : Courtship and battles of the males — Larger size of the females — Males, blight colours aud 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 con- spicuous colours of the female canuot he 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 — Yocal organs. Rep- tiles : Chelonians — Crocodiles — Snakes, colours in some cases protective — Lizards, battles of — Ornamental appendages — Strange differences in structure between the sexes — Colours — Sexual differences almost as great as with birds .. Page 1-37 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 38-98 VI CONTENTS OF VOL. II. CHAPTER XIV. Birds — continued. Choice exerted by the female — Length of courtship — Unpaired birds- — Mental qualities and taste for the beautiful — Preference or antipathy shewn by the 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 pheasant, and Urosticte .. .. Page 99-153 CHAPTER XV. Birds — continued. Discussion why the males alone of some species, and both sexes of other species, are brightly 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 154-182 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 differ- ences between the males of closely-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 World — Protccti ve colouring — Conspicuously-coloured birds — Novelty appreciated — Summary of the four chapters on birds 183-238 CONTENTS OF VOL. II. Vll CHAPTEE XYIT. Secondaky Sexual Characters of Mammals. The law of battle — Special weapons, confined to the males — Cause of absence of weapons in the female — Weapons common to both sexes, yet primarily acquired by the male' — Other uses ot such weapons — Their high importance — Greater size of the male Means of defence — On the preference shewn by either sex in the pairing of quadrupeds Page 239-273 CHAPTEE XVIII. Secondary Sexual Characters of Mammals — continued. Voice — Remarkable sexual peculiarities in seals — Odour — Deve- lopment of the hair — -Colour of the hair and skin — Anomalous 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 ornaments of the Quadrumana — Summary .. .. 274-315 CHAPTEE XIX. Secondary Sexual Characters of 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 316-354 Vlll CONTENTS OF VOL II. 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 ot sexual selection with man- kind— On the women in savage tribes having some power to choose their husbands — Absence of hair on the body, and deve- lopment of the beard — Colour of the skin — Summary 355-384 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 385-405 Index .. 406 SEXUAL SELECTION. CHAPTER XII. Secondary Sexual Characters of Fishes, Amphibians, and Reptiles. Pishes : 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 con- spicuous colours of the female cannot he 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 in some cases Protective — Lizards, battles of — Ornamental appendages — Strange differences in structure between the sexes — Colours - Sexual differences almost as great as with birds. ^ E have now arrived at the great sub-kingdom of the ei’tebrata, and will commence witli the lowest class, barnely Fishes. The males of Plagiostomous fishes (.s larks, rays) and of Chinneroid fishes are provided "ith claspers which serve to retain the female, like the 'ations structures possessed by so many of the lower ■Vu nials. Besides the claspers, the males of many rays a^e clusters of strong sharp spines on their heads, au< several rows along “ the upper outer surface of their pectoral fins.” These are present in the males of some species, which have the other parts of their bodies V°L. ix. j. 2 SEXUAL SELECTION. Part II. 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 liaia clavata, have their backs studded with large hook-formed spines.1 Owing to the element which fishes inhabit, little is known about their courtship, and not much about their battles. The male stickleback ( Gasferosteus Jei- urus) has been described 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 ma- “ terials for the nest, then back again in an instant; “ and as she does not advance lie endeavours to push “ her with his snout, and then tries to pull her by the “ tail and side-spine to the nest.”2 The males are said to be polygamists ;3 they are extraordinarily bold and pugnacious, whilst “ the females are quite pacific.” Their battles are at times desperate; “for these puny “ combatants 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. irachurus) 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,4 “ the bite of these little 1 Yarrell’s ‘ Hist, of British Fishes,’ vol. ii. 1836, p. 417, 425, 436. Dr. Gunther informs me that the spines in II. clavata are peculiar to the female. 2 See Mr. R. Waringtou’s interesting articles in 1 Annals and Mag. of Nat. Hist.’ Oct. 1852 and Nov. 1855. 8 Noel Humphreys, ‘River Gardens,’ 1857. 4 Loudon's ‘ Mag. of Natural History,’ vol. iii. 1830, p. 331. '-’HAP. XII. FISHES. 3 11 furies is very severe. They also use their lateral spiues “ with such fatal effect, that I have seen one during a “ battle absolutely rip his opponent quite open, so that “ he sank to the bottom aud died.” When a fish is conquered, “ his gallant bearing forsakes him ; his gay “ colours fade away; and he hides his disgrace among “ bis peaceable companions, but is for some time the “ constant object of his conqueror’s persecution.” The male salmon is as pugnacious as the little stickle- back; and so is the male trout, as I hear from Dr. Gunther. Mr. Shaw saw a violent contest between two I,!ale salmons which lasted the whole day ; and Mr. R. buist, Superintendent of Fisheries, informs me that he bas often watched from the bridge at Perth the males driving away their rivals whilst the females were spawn- big. 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.”5 The keeper of the Stormontfield breeding- pomls visited, as Mr. iiuist informs me, in June, 1868, the northern Tyne, and found about 300 dead salmon, all of which with one exception were 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 'c 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 5 ‘The Field,’ June 29th, 1867. For Mr. Shaw’s statement, see Edinburgh Review,’ 18-13. Another experienced observer (Scrope’s Days of Salmon Fishing,’ p. 60) remarks that the male would, if he could, keep, like the stag, all other males away. B 2 4 SEXUAL SELECTION. Paet II. “ the intermaxillary bones of tlie upper jaw.”6 (Figs. 26 and 27.) In our salmon this change of structure lasts only during the breeding-season ; but in the Salmo h/caodon of N.W. America the change, as Mr. J. K. Fig. 26. Head of male of common salmon (Salmo solar) during the breeding-season. [This drawing, as well as all the others in the present chapter, have been executed bv the well-known artist, Mr. (J. Ford, under the kind superintendence of Dr. Gunther from specimens in the British Museum.] 6 Yarrell, 1 History of British Fishes, ’ vol. ii. 1836. p. 10, Chap. XII. FISHES. 5 01 c believes, is permanent and best marked in the o c er males which have previously ascended the rivers, n t ese old males the jaws become developed into im- mense look-like projections, and the teeth grow into Withal ^ °^eU more ttan half an inch in length. 6 luoPean- salmon, according to Mr. Lloyd,8 a 1 ScaTiaintU'-a'iSt m ^ ancouver’s Island,’ vc , lavian Adventures,’ vol. i. 1854, p. 100, 104. vol. i. 1866, p. 6 SEXUAL SELECTION. Part II. the temporary hook-like structure serves to strengthen and protect the jaws, when one male charges another with wonderful violence ; but the greatly developed teeth ot‘ the male American salmon may be compared with the tusks of many male mammals, and they indicate an offensive rather than a protective purpose. The salmon is not the only fish in which the teeth differ in the two sexes. This is the case with many rays. In the thorn back (Ram clavata ) the adult male has sharp, pointed teeth, directed backwards, whilst those of the female are broad and flat, forming a pave- ment ; so that these 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 flat like those of the female. As so frequently occurs with secondary sexual characters, both sexes of some species of rays, for instance B. bath, possess, when adult, sharp, 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 B. maculata, but only when completely adult ; the males acquiring them at an earlier age than the females. We shall hereafter meet with analogous cases with certain birds, in which the male acquires the plumage common to both adult sexes, at a somewhat earlier age than the female. With other species of rays the males even when old never possess sharp teeth, and consequently botli sexes when adult are provided with broad, flat teeth like those of the young, and of the mature females of the above-mentioned species.9 As the rays are bold. 9 See Yarrell’s account of the Bays in his ‘ Hist, of British Fishes,’ vol. ii. 1836, p. 416, with an excellent figure, and p. 422, 432. Chap. XII. FISHES. 7 strong and voracious fishes, we 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. Carbonuier10 maintains that with almost all fishes the female is larger than the male ; and Dr. Gunther does not know of a single instance in which the male is actually larger than the female. itli some Cyprinodonts the male is not even half as large as the female. As with many kinds of fishes the males habitually fight together ; it is surprising that they have not generally become through the etiects of sexual selection larger and stronger than the females. The males suffer from their small size, for according to I'd • Carbonuier 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 pro- duction 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 great kindness of Dr. Gunther. I here 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 Qallionymus lyra has been called the gemrneous dragonet 10 As quoted in ‘ The Farmer,’ X86S, p. 3G9. 8 SEXUAL SELECTION. Pact II. “ from its brilliant gem-like colours.” When freshly taken 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 Lin- naeus and by many subsequent naturalists as a distinct Fig. 28. Calllonymus lyra. Upper figure, male; lower figure, female. N.B. I he lower figure is more reduced than the upper. species ; it is ot a dingy reddish-brown, with the dorsal fin brown and the other fins white. The sexes differ also in the proportional size of the head aud mouth, and in the position of the eyes ; 11 but the most striking differ- rence is the extraordinary elongation in the male (fig. 28) 11 I have drawn up this description from Yarrell’s ‘ British Fishes ’ vol. i. 1836, p. 261 and 266. Chap. XII. FISHES. 9 °f the dorsal fin. The young males resemble in struc- ture and colour the adult females. Throughout the genus Callionymus,13 the male is generally much more brightly spotted than the female, and iu several species, not only the dorsal, but the anal fin of the male is much elongated. rThe male of the Cottus scorpius , or sea-scorpion, is more lender and smaller than the female. There is also a gi'eat difference in colour between them. It is difficult, us Mr. Lloyd13 remarks, “for any oue, who has not seen ‘ this fish during the spawning-season, when its hues are ' brightest, to conceive the admixture of brilliant colours ! "’ith which it, in other respects so ill-favoured, is at ' that time adorned.” Loth sexes of the Labrus inixtus, although very different in colour, arc beautiful; the male being orange with bright-blue stripes, and the female bright-red with some black spots on the back. In the very distinct family of the Cyprinodontidse — '■"habitants of the fresh waters of foreign lands — the Sexes sometimes differ much in various characters. In the male of the Mollienesia petenensis the dorsal fin is greatly developed and is marked with a row of large, round, ocellated, bright-coloured spots ; whilst the same tin in the female is smaller, of a different shape, and "narked 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 torni, the Xiphophorus Hellerii (fig. 29), the inferior Margin of the anal fin is developed into a long filament, Catalogue of Acanth. Fishes in the British Museum,’ by Dr. ,3nt:her, 1861, p. 188-151. u wr-ame °f Sweden,’ &c., 18G7, p. 460. Br vf ttk respect to this and the following species I am indebted to (j1- Ciinther for information: see also his paper on the Fishes of en la,t America, in ‘ Transact. Zooiog. Soe.’ yol. vi. 1868, p. 485. 10 SEXUAL SELECTION. Part II. which is striped, as I hear from Dr. Gunther, 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 in colour and structure the adult females. Sexual differences such as these may be strictly compared with those which are so frequent with gallinaceous birds.15 Fig. 2'J. Xiphophoras Ilollerii. Upper figure, male ; lower figure, female. In a siluroid fish, inhabiting the fresh waters of South America, namely the Plecostomus barbatus 16 (fig. SO), the male has its mouth and interoperculum fringed with a beard of stiff hairs, of which the female shews 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 is Dr. Giintlier makes this remark; ‘Catalogue of Fishes in the British Museum,’ vol. iii. 1861, p. 141. 16 See Dr. Gunther ou tins genus, in ‘Proc. Zoolog. Soc.’ 1868, p. 232. CiiAr, XII. FISHES. 11 * ig' 30' I’lecostoinus barbatus. Upper figure, head of male ; lower figure, female. 12 SEXUAL SELECTION. Part II. 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 fila- ments can be useful in any ordinary way to the males alone. The Monacantlius scopag, which was shewn to me in the British Museum by Dr. Gunther, presents a nearly analogous case. The male 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 an inch and a half in length ; the female has on the same place a cluster of bristles, which may be compared with those of a tooth-brush. In another species, the M. peronii, the male has a brush like that possessed by the female of the last species, w'hilst the sides of the tail in the female are smooth. In some other species the same part of 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. In that strange monster, the Chimasra monstrosa, the male has a hook- shaped bone on the top of the head, directed forwards, with its rounded end covered with sharp spines ; in the female “ this crown is altogether absent,” but what its use may be is utterly unknown.17 The structures as yet referred to are permanent in the male after he has arrived at maturity ; but with some Blennies and in another allied genus 18 a crest is deve- loped on the head of the male only during the breed- U F. Buckland, in 1 Land and Water,’ July, 1868, p. 377, with a figure. 18 Dr. Giintlier, £ Catalogue of Fishes,’ vol. iii. p. 221 and 240. chap. XII. FISHES. 13 lng-season, and their bodies at the same time become ’ftore brightly-coloured. There can be little doubt that this crest serves as a temporary sexual ornament, for the female does not exhibit a trace of it. In other species °f the same genus both sexes possess a crest, and in at least one species neither sex is thus provided. In this °ase and in that of the Monacantlius, we have good in- stances to how great an extent the sexual characters of closely-allied forms may differ. In many of the Chro- rQ1'(lEe, for instance in Geophagus and especially in Cichla, the males, as I hear from Professor Agassiz, 1S have a con- spicuous protuberance on the forehead, which is wholly Wanting in the females and in the young males. Pro- fessor Agassiz adds, “ I have often observed these fishes at the time of spawning when the protuberance 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 in their periodical appear- ailce resemble the fleshy caruncles on the heads of cer- tain birds ; but whether they serve as ornaments must remain at present doubtful. f'he males of those fishes, which differ permanently in colour from the females, often become more brilliant, as hear from Professor Agassiz and Dr. Gunther, during 1(1 breeding-season. This is likewise the case with a Multitude of fishes, the sexes of which at all other seasons of the year are identical in colour. The tench, l0ach, and perch may he given as instances. The male salmon at this season is “ marked on the cheeks with 29ft66 a^S0 ‘ ^ Jolmiey in Brazil,’ by Prof, and Mrs. Agassiz, 1868. 14 SEXUAL SELECTION. Part II. “ orange-coloured stripes, which give it the appearance “ of a Labrus, and the body partakes of a golden-orange “ tinge. The females are dark in colour, and are com- “ monly called black-fish.*’ 20 An analogous and even greater change takes place with the Salmo eriox or bull- trout ; the males of the char (S. umbla ) are likewise at this season rather brighter in colour than the females.21 The colours of the pike (Esox reticulatus) of the United States, especially of the male, become, during the breeding-season, exceedingly intense, brilliant, and iri- descent.22 Another striking instance out of many is afforded by the male stickleback (Gasterosteus leiurus), which is described by Mr. Warington,23 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 glowed with an in- “ ternal 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. That with fishes there exists some close relation between their colours and their sexual functions we can clearly see : — firstly, from the adult males of certain species being differently coloured from the females, and often much more brilliantly ; — secondly, from these same a> Yarrell, ‘British Fishes,’ vol. ii. lS3ti, p. 10, 12, K5. W. Thompson, in ‘ Annals and Mag. of Nat. History,’ vol. vi. 1841, p. 440. 32 ‘ The American Agriculturist,’ 1S68, p. 100. 23 ‘ Annals and Mag. of Nat. Hist.’ Oct. 1852. Chap, xil. FISHES. 15 ^ales, whilst immature, resembling the mature females ; uud, lastly, from the males, even of those species "liieh at ali other times of the year are identical in colour with the females, often acquiring brilliant tints during the spawning-season. We know that the males are ardent in their courtship and sometimes fight despe- rately together. If we may assume that the females aave the power of exerting a choice and of selecting the |lloro highly-ornamented males, all the above facts occorne intelligible through the principle of sexual election. On the other hand, if the females luxbi- f Hally deposited and left their ova to be fertilised by first male which chanced to approach, this fact "°uld be fatal to the efficiency of sexual selection; for there could be no choice of a partner. But, as far known, the female never willingly spawns except the close presence of a male, and the male never e,'tilises the ova except in the close presence of a female. It is obviously difficult to obtain direct avidence with respect to female fishes selecting ‘eir partners. An excellent observer,24 who carefully Htched the spawning of minnows ( Cyprinus phoxinus), Remarks that owing to the males, which were ten times numerous as the females, crowding closely round 1( Ie|u> he could “ speak only doubtfully on their opera- t( tions. When a female came among a number of uiales they immediately pursued her; if she was not „ lfca<1y for shedding her spawn, she made a precipitate t letreat ; but if she was ready, she came boldly in <( araong them, and was immediately pressed closely by „ a. llJale on each side ; and when they had been in that t, ‘slfuatiou a short time, were superseded by other two, " 10 wedged themselves in between them and the 24 Loudon’s ‘Mag. of Nat. Hist.’ vol. v. 1832, p. 681.. 16 SEXUAL SELECTION. Paet II. “ female, who appeared to treat all her lovers with “the same kindness.” Notwithstanding this last state- ment, I cannot, from the several previous considera- tions, give up the belief that the males which are the most attractive to the females, from their brighter colours or other ornaments, are commonly preferred by them ; and that the males have thus been rendered more beautiful in the course of ages. We have next to inquire whether this view can be extended, through the law of the equal transmission of characters to both sexes, 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. joavo), described,25 with pardonable exaggeration, as formed of polished scales of gold encrusting lapis- 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 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 surround- ing conditions, without any aid from selection. The gold-fish (Cyprinus auratus ), judging from the analogy of the golden variety of the common carp, is, perhaps, a ease 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 confinement. It is, however, more probable that these colours have been intensified through artificial selection, as this spe- cies has been carefully bred in China from a remote 25 Bory de Saint Vincent, in ‘Diet. Class. d’Hist, Nat.’ torn.ix. ISiU. p. 151. Cha,p, yjj FISHES. 17 period.26 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 re- viving some benefit from so great a change, and conse- •prently without the intervention of natural selection. ^ hat, then, must we conclude in regard to the many ^hes, both sexes of which are splendidly coloured? br. Wallace27 believes that the species which frequent reefs, where corals and other brightly-coloured organisms abound, are briglitly coloured in order to escape detec- tion 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 arc beau- tr fully coloured, and many of the carnivorous Cypri- I'ldse in India are ornamented with “ bright longitu- dinal lines of various tints.” 28 Mr. M‘Clelland, 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 "inch are destined to keep the number of these fishes Ul check ; ” but at the present day few naturalists will Y ' .Owing to some remarks on this sutyect, made in my work ‘ On the Cation 0f Animals under Domestication,’ Mr. \V. F. Mayers an . ese kotes and Queries,’ Aug. 1868, p. 123) has searched the ^ cient Chinese encyclopedias. He limls that gold-fish were first Ann’'11 ocm^hement during the Sung Dynasty, which commenced it 1 ’ . ' tu the year 1129 these fishes abounded. In another place “cT Sa^ s‘ni'° the year 1548 there has been “ produced at llang- u Ww.a variety called the fire fish, from its intensely red colour. It “ o il!?’versiaUy admired, and there is not a household where it is not V i^a^e unless one sex is exposed for a longer period to danger, or has less power of escaping from such danger than the other sex ; and it does not appear that "ith fishes the sexes differ in these respects. As far as there is any difference, the males, from being generally smaller size, and from wandering more about, are exposed to greater danger than the females ; and yet, 'vken the sexes differ, the males are almost always the ^ost conspicuously coloured. The ova are fertilised Bnmediately after being deposited, and when this pro- Cess lasts for several days, as in the case of the salmon,30 the female, during the whole time, is attended by the n'ale- 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 11,1 P°i' taut 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 pre- Sei'ved, and both would have an equal infiuenco on the c°l°urs of their offspring or the race. Certain fishes, belonging to several families, make llests ; and some of these fishes take care of their •°Ung when hatched. Both sexes of the brightly- coloured Crenilabrus massa and melons work together in nilding their nests with sea-weed, shells, &c.31 But the tt'ales 0f certajn fis]ieg (|0 ail the work, and afterwards d ve exclusive charge of the young. This is the case m Yarrell> ‘ British Fishes,’ vol. ii. p. 11. e . '“-CC01'ding to the observations of M. Gerbe; see Gunther’s ‘Ke- °f Zoolog. Literature,’ 1865, p. 194. 20 SEXUAL SELECTION. Pap.t II. with the dull-coloured gobies,32 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 (G. leiurus ) per- forms during a long time the duties of a nurse with exemplary care and vigilance, and is continually employed in gently leading hack 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 dx-ive her from the nest.33 The males of certain other fishes inhabiting South America and Ceylon, and belonging to two distinct orders, have the extraordinary habit of hatching the eggs laid by the females within their mouths or branchial cavities.84 With the Amazonian species which follow this habit, the males, as I am informed by the kindness of Professor Agassiz, “not only are generally brighter “ than the females, hut 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 deve- loped ou the forehead of the males during the breeding- season. W ith the various species of Chrom ids, as Pro- lessor Agassiz likewise informs me, sexual differences Cuvier, ‘ Eegne Atiimal,’ vol. ii. 1829, p. 212. :!;i See Mr. Warington’s most interesting description of the habits of the Gasterosteus leiurus, in ‘Annals anil Mag. of Nat. Hist.’ November, 1855. 84 Prof. Wyman, in ‘Proc. Boston Soe. of Nat. Hist.’ Sept. 15, 1857. Also W. Turner, in ‘Journal of Anatomy and Pliys.’ Nov. 1, 1866, p. 78. Dr. Gunther has likewise described other cases. Chap. xii. FISHES. 21 111 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 without “ 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 ; tor ‘ instance, Ilygrogonus is bright green, with large black ocelli, encircled with the most brilliant red. ^ hether with all the species of Chromids it is the male aione which sits on the eggs is not known. It is, however, manifest that the fact of the eggs being pro- moted or unprotected, has bad little or no influence on hho differences in colour between the sexes. It is fur- ther manifest, in all the cases in which the males take delusive charge of the nests and young, that the destruction of the brighter-coloured males would be far m°re 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 ihese could not inherit bis peculiarities; yet, in many °f these very cases the males are more conspicuously c‘°loured than the females. In most of the Lophobranchii (Pipe-fish, Hippo- eaurpi, &c.) the males have either marsupial sacks or hemispherical depressions on the abdomen, in which f le ova laid by the female are batched. The males a 80 shew great attachment to their young.® The r?Xes do not commonly differ much in colour ; hut Dr. -* iinfher believes that the male Hippocampi are rather ' rigliter than the females. The genus Solenostoma, Yarrell, ‘ Hist, of British Fishes,’ vol, ii. 1836, p. 329, 338. 35 22 SEXUAL SELECTION. Part II. however, offers a very curious exceptional case,36 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 Lophobranekii 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 Solenostoma takes the same charge and is brighter than the male, it might be argued that the conspicuous colours of the sex which is the most important of the turn for the welfare of the offspring must serve, in some manner, as a protection. But from the multitude of fishes, the males of which are either permanently or periodically brighter than the females, but whose life is not at all more important than that of the female for the welfare of the species, this view can hardly be maintained. When we treat of birds we shall meet with analogous cases in which there has been a complete inversion of the usual attri- butes 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 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 orna- 36 Dr. G iinther, since publishing an account of this species in ‘The Fishes of Zanzibar,’ by Col. Playfair, 1866, p. 137, lias re-examined the specimens, and has given me the above information. Chap. XII. FISHES. 23 Cental characters, the males originally varied, with their '’aviations transmitted to the same sex, and accumulated through sexual selection by attracting or exciting the females. In many cases, however, such characters have beeu 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 lor this purpose. -t he last point which need be noticed is that in many Parts of the world fishes are known to make peculiar Noises, which are described in some cases as being Musical. Very little has been ascertained with respect to the means by which such sounds are produced, and evei1 less about their purpose. The drumming of the Urubrinas in the European seas is said to be audible h°in a depth of twenty fathoms. The fishermen ol 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.” 37 If this statement is trustworthy, we have an instance in this, the lowest class of the Vertebrata, of what we shall find prevailing throughout the other vertebrate classes, au'l which prevails, as we have already seen, with insects and spiders ; namely, that vocal and instru- mental sounds so commonly serve as a love-call or as a love-charm, that the power of producing them was probably first developed in connection with the propa- gation of the species. 37 Thu Rev. C. Kingsley, in ‘Nature,’ May, 1870, p. i0. 24 SEXUAL SELECTION. I’art ii- Amphibians. Urodela. — First for the tailed amphibians. The sexes of salamanders or newts often differ much both in colour and structure. In some species prehensile claws are developed on the fore-legs of the males during the breeding-season; and at this season in the male Triton palmipes the hind-feet are provided with a swimming web, which is almost completely absorbed during the winter; so that their feet then jig. .11. I riton cristatus (half natural size, from Bell’s ‘British Reptiles’), ppei figure, male during the breeding-season; lower figure, female. resemble those of the female.38 This structure no doubt aids the male in his eager search and pursuit of the female. With our common newts ( Triton punctatus and cristatus ) a deep, much-indented (west is developed along the back and tail of the male during the breed- ing-season, being absorbed during the winter. It is not furnished, as Mr. St. George Mivart informs me, 3S Bell, ‘ History of British Beptiles,’ 2nd edit. 1849, p. 156-159. C"AI>. XII. AMPHIBIANS. 25 "’ith muscles, and therefore cannot be used for loco- motion. As during the season of courtship it becomes 0<%ed with bright colours, it serves, there can hardly 30 a doubt, as a masculine ornament. In many species the body presents strongly contrasted, though lurid tints ; and these become more vivid during the J1'eedi ng-season. The male, for instance, of our com- mon little newt ( Triton pundatus ) is “ brownish-grey c ahove, passing into yellow beneath, which in the K sI»ing becomes a rich bright orange, marked every- 1 "’here with round dark spots.” The edge of the crest a 80 is then tipped with bright red or violet. The eiaale is usually of a yellowish-brown colour with scattered brown dots; and the lower surface is often cbute plain.39 The young are obscurely tinted. The 0Va are fertilised during the act of deposition and are n°t subsequently tended by either parent. We “my therefore conclude that the males acquired their i°ngly-markcd colours and ornamental appendages l0Ugh sexual selection ; these being transmitted either Ue male offspring alone or to both sexes. ^Q^nuTa 01 Batrachia. — With many frogs and toads ^ 6 colours evidently serve as a protection, such as 6 bright green tints of tree-frogs and the obscure 1 fled shades of many terrestrial species. The most tp k’Cuously coloured toad which I ever saw, namely 0j.e ^ lrynisGus nigricans ,10 had the whole upper surface an l *e k°cly as black as ink, with the soles of the feet v . ?ai'^s the abdomen spotted with the brightest gra U 10n’ ^ crawled about the bare sandy or open ‘ sy plains of La Plata under a scorching sun, and « ibid. p. 146, 151. Mr ,°olo§y of the Voyage of the “ Beagle,” ’ 1843. “ Reptiles, ” by ' ■Deu> p. 49. 26 SEXUAL SELECTION. Part II. could not fail to catcli the eye of every passing creature. These colours may be beneficial by making this toad known to all birds of prey as a nauseous mouthful ; for it is familiar to every one that these animals emit a poisonous secretion, which causes the mouth of a dog to froth, as if attacked by hydrophobia. 1 was the more struck with the conspicuous colours of this toad, as close by I found a lizard ( Prodotreius multimaculatus) which, when frightened, flattened its body, closed its eyes, and then from its mottled tints could hardly be distinguishable from the surrounding sand. With respect to sexual differences of colour, Ur. Gun- ther knows of no striking instance 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 Ur. Gunther know of any striking difference in external structure between the sexes, excepting the prominences which become developed during the breed- ing-season on the front-legs of the male, by which lie is enabled to hold the female. The Megalojphrys mon- tana'" (fig. 82) offers the best case of a certain amount of structural difference between the sexes; for in the male the tip of the nose and the eyelids are produced into triangular flaps of skin, and there is a little black tubercle on the back — characters which are absent, or only feebly developed, in the females. It is surprising that frogs and toads should not have acquired more strongly-marked sexual differences ; for though cold- blooded, their passions are strong. Ur. 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. 41 ‘ The Beptiles of India,’ by Dr. A. Gunther, Bay Soe. 1864, p. 413. C«AP. XII. AMriilBIANS. 27 f hese animals, however, offer one interesting sexual merenee, namely in the musical powers possessed by males ; hut to speak of music, when applied to the ' Mordant and overwhelming sounds emitted by male JU H-frogs and some other species, seems, according to °Ur taste, a singularly inappropriate expression. Never- theless certain frogs sing in a decidedly pleasing man- aer- Near llio de Janeiro I used often to sit in the ev’ening to listen to a number of little Hylrn, which, 32. Megalophrys montana. The two left-hand figures, the male ; the two right-hand figures, the female. j?Pl(,hed on blades of grass close to the water, sent U1th sweet chirping notes in harmony. The various l°UQ(is are emitted chiefly by the males during the /’^'ding-season, as in the case of the croaking of our c‘°ttmion frog.42 In accordance with this fact the vocal lagans of the males are more highly developed than °Se of the females. In some genera the males alone 42 Belt, 1 History of British. Beptiles,’ 184!), p. 93. 28 SEXUAL SELECTION. Part II. are provided with sacs which open into the larynx.43 For instance, in the edible frog (liana eseulenfa ) “the “ sacs are peculiar to the males, and become, when filled “ with air in the act of croaking, large globular blad- “ ders, standing 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.44 The vocal organs differ considerably in structure in the several genera of the family ; 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 ( Ohrysemys picta) has claws on its front-feet twice as long as those of the female ; and these are used when the sexes unite.43 With the huge tortoise of the Gala- pagos Islands ( Testudo 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 he heard at the dis- tance of more than a hundred yards ; the female, on the other hand, never uses her voice.46 Crocodilia. — The sexes apparently do not differ in 43 J- Bishop, in ‘ Todd’s Cyclop, of Anat. and Phys.’ vol. iv. p. 1503. 44 Bell, ibid. p. 112-114. 45 Mr. C. J. Maynard, 1 The American Naturalist,’ Dec. 1869, p. 555. 46 See mv ‘Journal of Researches during the Voyage of the Beagle,” ’ 18.45, p. 384. XII. REPTILES. 29 colour ; nor do I know tkat the males fight together, though this is probable, for some kinds make a prodi- 8’ous display before the females. Bartram 47 describes male alligator as striving to win the female by splashing and roaring in the midst of a lagoon, “ swollen (( t° an extent ready to burst, with his head and tail {£ fitted up, 116 spins or twirls round on the surface of tlle water, like an Indian chief rehearsing his feats . °f War.” During the season of love, a musky odour Js emitted by the submaxillary glands ot the crocodile, llt|d pervades their haunts.48 ^phidia. — I have little to say about Snakes. Dr. ■fintlier informs me that the males are always smaller man the females, and generally have longer and slen- °eies ; f01. instance, of the coral-snakes of S. America, llch are of a rich red with black and yellow transverse ^mds, j Well remember how much surprise I felt at le beauty of the first coral-snake which I saw gliding 'lCross a path in Brazil. Snakes coloured in this peculiar manner, as Mr. Wallace states on the authority of Dr. unther m are found nowhere else in the world except k. America, and here no less than four genera occur. (j. e. these, Elaps, is venomous ; a second and widely- lstmct genus is doubtfully venomous, and the two others 110 quite harmless. The species belonging to these dis- *7 genera inhabit the same districts, and are so like and which in the beauty of their colours baffle escription; are furnished with skiuny appendages to the •roat, “lifie the wattles of gallinaceous birds.” These ecome erected when the animal is excited. They occur 111 both sexes, but are best developed in the male when ari'ived at maturity, at which age the middle appendage 8 sometimes twice as long as the head. Most of the sPecie8 likewise have a low crest running along the ! and this is much more developed in the full- hr°wn males, than in the females or young males."’6 Fig. 33. Sitana minor. Male, with the gular pouch expanded (from Gunther’s ‘Rep- tiles of India’). atln these statements and quotations, in regard to Cophotis, Sitana raco, as well as the following facts in regard to Ceratophora, are VOL. xi. D 34 SEXUAL SELECTION. Part II. There are other and much more remarkable dif- ferences between the sexes of certain lizards. The male of Ccratophora aspera bears on the extremity of his snout an appendage half as long as the head. It is cylindrical, covered with scales, flexible, and appa- rently 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 ; and in a third species (C- Stocldartii, fig. 34 ) the whole appendage is converted into a horn, which is usually of a white colour, but as- sumes 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 is of quite minute size in the female and in the young. These appen- dages, as Dr. Gunther has remarked to me, may be compared with the combs of «g. 34. ceratophora stoddartii. upper gallinaceous birds, and appa- figure, mule; luwer figure, female 6 fl ently serve as ornaments. In the genus Chamaeleon we come to the climax of difference between the sexes. The upper part of the slcull of the male C. Ufurcus (fig. 35), an inhabitant of Madagascar, is produced into two great, solid, bony pro- jections, covered with scales like the rest of the head ; and of this wonderful modification of structure the female exhibits only a rudiment. Again, in Cliamieleon OivenU (%. 36), from the West Coast of Africa, the male bears taken from Dr. Gunther’s magnificent work on the ‘ Eeptiles of British India,’ Kay Soc. 18G4, p. 122, 130, 135. ClJAl. XII. REPTILES. 35 011 his snout and forehead three curious horns, of which *he female has not a trace. These horns consist of an excrescence of bone covered with a smooth sheath, Arming part of the general integuments of the body, so that they are identical in structure with those of a 35. Chameleon bifurcus. Upper figure, male; lower figure, female,. foill, goat, or other sheath-horned ruminant. Although le three horns differ so much in appearance from *e two great prolongations of the skull in C. bifurcus, ''e can hardly doubt that they serve the same general 1 arpose in the economy of these two animals. The 36 SEXUAL SELECTION. Pabt II- first conjecture which will occur to every one is that they are used by the males for fighting together ; but Dr. Gunther, to whom I am indebted for the foregoing details, does not believe that such peacable crea- tures would ever become pugnacious. Hence we are with the previously-mentioned Cophotis and with the Acantliodactijlus capensis of S. Africa. In a Cordylus of the latter country, the male is either much redder or greener than the female. In the Indian Calotes nigri- labris there is a greater difference in colour between the sexes ; the lips also of the male are black, whilst those of the female are green. In our common little viviparous lizard ( Zootoca vivipara ) “ the under “ side of the body and base of the tail in the male arc “ bright orange, spotted with black; in the female “ these parts are pale greyish-green without spots.”4' We have seen that the males alone of Sitana possess a driven to infer that these almost mon- strous deviations of structure serve as masculine orna- ments. Fig. 36. Chameleon Owenii. Upper figure, male ; lower figure, female. With many kinds of lizards, the sexes differ slightly in co- lour, the tints and stripes of the males being brighter and more distinctly de- fined than in the females. This, for instance, is the case 57 Bell, ‘ History of British Bepliles,’ 2nd edit. 1S49, p. 40. C|up. xn. REPTILES. 37 throat-pouch ; and this is splendidly tinted with blue, J ar'b, and red. In the Proctotretus tenuis of Chile the Illide alone is marked with spots of blue, green, and CoPpery-red.68 I collected in S. America fourteen species of this genus, and though I neglected to record sexes, I observed that certain individuals alone were ‘"orbed with emcrald-like green spots, whilst others ‘acl orange-coloured gorges ; and these in both cases n° doubt were the males. 11 tlie foregoing species, the males are more brightly coloured than the females, but with many lizards both ^Xes are coloured in the same elegant or even magni- Cei‘t manner ; and there is no reason to suppose that ^ch conspicuous colours are protective. With some 1Zards, however, the green tints no doubt serve for C0lmealnient ; and an instance has already been inci- 'entjy gjven 0£ one Specieg 0f Proctotretus which resembles the sand on which it lives. On the closely I ^°lo 've may conclude with tolerable safety that the dutiful colours of many lizards, as well as various appendages and other strange modifications of structure, j.dV° been gained by the males through sexual selection °r the sake of ornament, and have been transmitted P er to their male offspring alone or to both sexes. .^-Xual selection, indeed, seems to have played almost as Important a part, with reptiles as with birds. Put the ?s conspicuous colours of the females in comparison yj those of the males cannot be accounted for, as * ' " allace believes to be the case with birds, by the Posure of the females to danger during incubation. aS pi ^ Re))ti|'.)r,Proc,°trenis see -Zoology of the Voyage of the “Beagle:” of ^ ,c 8’. by Mr. Bell, p. 8. For tl.e Lizards of S, Africa, see ‘ Zoology lojh ‘,lca : Reptiles,’ by Sir Andrew Smith, pi. 25 and 39. For the '-“lotos, see ‘ Reptiles of British India,’ by Dr. Gunther, p. 143. 38 SEXUAL SELECTION. Part It CHAPTER XIII. Secondary Sexual Characters of Birds. Sexual differences — Law of Battle — Special weapons — Vocal organs — Instrumental 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 conspicuous in birds, though not perhaps entailing more important changes of structure, than iu any other class of animals. I shall, therefore, treat the subject at con- siderable length. Male birds sometimes, though rarely, possess special weapons for fighting with each other. They charm the females by vocal or instrumental music of the most varied kinds. They are ornamented by all sorts of combs, wattles, protuberances, horns, air- distended sacs, topknots, naked shafts, plumes and lengthened feathers gracefully 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 fan- tastic antics performed either on the ground or in the air. Iu one instance, at least, the male emits a musky odour which wTe may suppose serves to charm or excite the female ; for that excellent observer, Mr. Ramsay,1 says of the Australian musk-duck (Biziura lobata ) that “ the “ smell which the male emits during the summer “ months is confined to that sex, and iu some indi- “ viduals is retained throughout the year ; I have never 1 ‘Ibis,’ vol. iff, (new series) 1867, p. 414. Chap. XIII. BIRDS. 39 even in the breeding-season, shot a female which had “ any smell of musk.” So powerful is this odour during the pairing-season, that it can be detected long bcfoie the bird can be seen.2 On the whole, birds appear to he the most msthetic of all animals, excepting ot course lna,i, and they have nearly the same taste for the beau- tiful as we have. This is shewn by our enjoyment of the singing of birds, and by our women, both civilised aud 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. Before treating of the 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 Senus Eustephanus, which inhabit the island ot .luan Fernandez, were long thought to be specifically distinct, but are now known, as Mr. Gould informs me, to be the ®eXes of the same species, and they differ 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 m,>ch from that of the female. In the curious Neomor- Pha of Hew Zealand, there is a still wider difference in lbe form of the beak ; and Mr. Gould has been informed fbat the male with his “ straight and stout beak tears the bark of trees, in order that the female may on the uncovered larvce with licr weaker and moie curved beak. Something of the same kind may be observed with our goldfinch (Cardueli s elerjans), tor I 2 Gould, < Handbook to the Birds of Australia,’ 1865, vol. ii. p. 383. 40 SEXUAL SELECTION : BIRDS. Part II.' am assured by Mr. J. Jenner Weir that the bird- catchers can distinguish the males by their slightly longer beaks. The flocks of males, as an old and trust- worthy bird-catcher asserted, are commonly found feed- ing 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 slight difference of this nature as a foundation, we can see how the beaks of the two sexes might be made to differ greatly through natural selection. In all these eases, however, especially in that of the quarrelsome humming-birds, it is possible that the differences in the beaks may have been first acquired by the males in relation to their battles, and afterwards led to slightly changed habits of life. Law of Battle. — Almost all male birds are extremely pugnacious, 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 hum- ming-bird, is one of the most quarrelsome. Mr. Gosse 3 describes a battle, in which a pair of humming-birds seized hold of each other’s beaks, and whirled round and round, till they almost fell to the ground ; and M. Montes de Oca, in speaking of another genus, 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.”4 With Waders, the males of the common water-hen ( Gallinula chlorojpus) “ when pairing, fight violently for the females : “ they stand nearly upright in the water and strike “ with their feet.” Two were seen to be thus efieaeed O O 3 Quoted by Mr. Gould, 1 Introduction to the Trochilidaj,’ 1861 p. 29 4 Gould, ibid. p. 52. CiUp. XIII. ■ LAW OF BATTLE. 41 half an hour, until one got hold of the head of the °ther which would have been killed, had not the ob- s« ver interfered ; the female all the time looking on as a duiet spectator.5 The males of an allied bird ( Galli - wistutux), as Mr. Blyth informs me, are one third '^'ger than the females, and are so pugnacious during breeding-season, that they are kept by the natives ot Eastern Bengal for the sake of lighting. Various ler birds are kept in India for the same purpose, for ^stance the Bulbuls ( Pycnonotus hsemorrhous) which %ht with great spirit.” 6 1 be polygamous Ruff ( Machetes puynax, fig. 37) is glorious for his extreme pugnacity; and in the spring, ,, e 'nates, which are considerably larger than the morales, congregate day alter day at a particular spot, fhere the females propose to lay their eggs. The s°'vlers discover these spots by the turf being trampled 0>UQWhat bare. Here they fight very much like game- 0chs, seizing each other with their beaks and striking ll j their wings. The great ruff of feathers round the t(eck is then erected, and according to Ool. Montagu c ®Weeps the ground as a shield to defend the more euc*er parts;” and this is the only instance known to shield n*e iu the case of birds, of any structure serving as a The ruff of feathers, however, from its varied 1 rich colours probably serves in chief part as an ^u«nent. Like most pugnacious birds, they seem kil'.ays ready to fight, and when closely confined often p ea)'h other; but Montagu observed that their luif!laCity becomes greater during the spring, when the at ^ , b-athers on their necks are fully developed; and ds period the least movement by any one bird J • ^kompson, ‘Nat. Hist, of Ireland : Birds,’ 'aon. ‘ Birds of India,’ 1803, vol. ii. p. 90. vol. ii. 1850, p. 327 42 SEXUAL SELECTION : BIEDS. Part It provokes a general battle.7 Of the pugnacity of web- footed birds, two instances will suffice : in Guiana “ bloody “fights occur during the breeding-season between the 7 Macgillivray, 1 Hist. Brit. Birds,’ vo). iv. 1852, p. 177-181. LAW OF BATTLE. 43 t'n XIII. (( males of the wild musk-duck ( Cairina moscliata) ; aud where these fights have occurred the river ‘‘ is covered for some distance with feathers.”8 Birds "hich seem ill-adapted for fighting engage in fierce conflicts ; thus with the pelican the stronger males j 1 'v° away the weaker ones, snapping with their '’'Re beaks and giving heavy blows with their wings. 5a]e snipes fight together, “tugging and pushing each ( other with their bills in the most curious manner lrnaginable.” Some few species are believed never to 1 pB t ; this is tlie case, according to Audubon, with one °| ,ll« woodpeckers of the United States {Ticus ciuratus), a though “ the hens are followed by even halt a dozen their gay suitors.” 9 Tl*e males of many birds are larger than the females, this no doubt is an advantage to them in their titles with their rivals, and has been gained through aexual selection. The difference in size between the "o sexes is carried to an extreme point in several Australian species ; thus the male musk-duck (Biziura) a!^ fl'e male Cincloramphus cruralis (allied to our j'd’jts) are by measurement actually twice as large as weir respective females.10 With many other birds the 6luales are larger tbau the males; aud as formerly Remarked, the explanation often given, namely that the crjutles have most of the work in feeding their young, 1 1 uot suffice. In some few cases, as we shall here- a^er see, the females apparently have acquired their Sweater size and strength for the sake of conquering er females and obtaining possession of the males. Sehoinburgk, in ‘Journal of B. Geograph. Soc.’ vol. xiii. sel * ^“hUological Biography,’ vol. i. p. 191. Bor pelicans and snipes, 1. !!}• lii- P- 381, 177. Gould, ‘Handbook of Birds of Australia,’ vol. i. p. 395; vol. n. p. 383. 44 SEXUAL SELECTION : BIRDS. Part II- The males of many gallinaceous birds, especially of the polygamous kinds, are furnished with special weapons for fighting with their rivals, namely spurs, which can be used with fearful effect. It has been recorded by a trustworthy writer11 that in Derbyshire a kite struck at a game-hen accompanied by her chickens, w'hen 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 liis 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 following brutal scene, told me that a bird had both its legs broken by some accident in the cock-pit, 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 closely-allied aud wild species, the Gallus Stanleyi, is known to fight desperately “ in “ defence of his seraglio,” so that one of the combatants is frequently found dead.12 An Indian partridge ( OritJ ■ gornis gularis), the male of which is furnished with strong and sharp spurs, is so quarrelsome, “that the “ scars of former fights disfigure the breast of almost “ every bird you kill.” 13 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 11 Mr. Hewitt in the ‘ Poultry Book by Tegetmeier,’ 1866, p. 137. 12 Layard, ‘ Annals and Mag. of Nat. Ilist.’ vol. xiv. 1854, p. 63. 13 Jerdon, ‘ Birds of India,’ vol. iii. p. 574. LAW OF BATTLE. 45 C'Up. XIII. Black-, Wll rluriri %ht cock ( Tetrao urog alius and T. tetrix), which are polygamists, have regular appointed places, where g many weeks they congregate in numbers to - together and to display their charms before the ^‘Oales. ]\I. \V. Kowalevsky informs me that in Russia le bas seen the snow all bloody on the arenas where „ e Capercailzie have fought ; and the Black-cocks ^ ^ake the feathers fly in every direction,” when ovexal “engage in a battle royal.” The elder Brehm "es a curious account of the Balz, as the love-dance ry.1 ^ve-song of the Black-cock is called in Germany. ’.e bird utters almost continuously the most strange ls°'Ses : “ he holds his tail up and spreads it out like a « u"’ be lifts up his head and neck with all the feathers (! ?lect> and stretches his wings from the body. Then takes a few jumps in different directions, some- in a circle, and presses the under part of his “be “times “ b V <( a c so hard against the ground that the chin-feathers « rnbhed off. During these movements he beats « 8 w'ngs and turns round and round. The more (( c c ent he grows the more lively he becomes, until at 8 s ' the bird appears like a frantic creature.” At beCU timeS tlle black-cocks are so absorbed that they CaCortle almost blind and deaf, but less so than the tl I lcailzie; hence bird after bird may be shot on After the Perf^1^6 Sl,0t’ or even caught by the hand, the °lrning these antics the males begin to fight : and Same black-cock, in order to pi-ove his strength over feveral antagonists, will visit in the course of one morn- Sevei'al Balz-places, which remain the same during "««*»! years.1* rois 1 Ulust. TMerletjen,’ 1807, D. iv. s. 851. Some of the foie- > 6meilts are taken from L. Lloyd, ‘ The Game Birds of U’ &c.. 1867, p. 79. SEXUAL SELECTION : BIRDS. Part It 46 The peacock with his long train appears more like 9 dandy than a warrior, but he sometimes engages i° fierce contests: the Rev. W. Darwin Fox informs ®c that two peacocks became so excited whilst fighting a* some little distance from Chester that they flew over the whole city, still fighting, until they alighted on tk® top of St. John's tower. The spur, in those gallinaceous birds which are thus provided, is generally single; but Polyplectron (se® fig. 51 , p. 90) has two or more on each leg ; and one of the Blood-pheasants ( Ithaginis emeritus ) has been seel1 with five spurs. The spurs are generally confined to tk® male, being represented by mere knobs or rudiments 111 the female; but the females of the Java peacock (PaV° muticus ) and, as 1 am informed by Mr. Blvth, of the small fire-backed pheasant ( Euplocamus erythropthalmus) p«s' sess spurs. In G-alloperdix it is usual for the males t® have two spurs, and for the females to have only on® on each leg.18 Hence spurs may safely be considered as a masculine character, though occasionally transferred in a greater or less degree to the females. Like most other secondary sexual characters, the spurs are highly variable both in number and development in the sa®® species. Various birds have spurs on their wings. But tk® Egyptian goose ( Chenalopex ssgyptiacus ) has only “ bai’6’ “ obtuse knobs,” and these probably shew us the firs steps by which true spurs have been developed in other allied birds. In the spur-winged goose, Pledropter $ gambensis, the males have much larger spurs than tk® females ; and they use them, as I am informed by Jl1’1 Bartlett, in fighting together, so that, in this case, tlF 15 Jerdon, * Birds of India on Ithaginis, vol. iii. p. 523 ; on Gall0' perdix, p. 541. ClUf. XIII. LAW OF BATTLE, 47 j'/'g-spurs serve as sexual weapons ; but according to Vlngstone, they are chiefly used in the defence of the • °Utlg- The Palamedea (fig. 88) is armed with a pair of Palamedea cornuta (Irom Brehra), shewing the double- wing-spurs, and the filament on the head. 48 SEXUAL SELECTION : BIRDS. Part j spurs on eacli wing ; and these are such formidable we»' pons that a single blow has driven a dog howling away- But it does not appear that the spurs in this case, or i" that of some of the spur-winged rails, are larger in the male than in the female.10 In certain plovers, howeveL the wing-spurs must be considered as a sexual character- Thus in the male of our common peewit ( Vanellus crt? tatus ) the tubercle on the shoulder of the wing become® more prominent during the breeding-season, and the males arc known to fight together. In some speck5 of Lobivanellus a similar tubercle becomes develop®^ during the breeding-season “into a short horny spur. In the Australian L. lobatus both sexes have spurs, bid these are much larger in the males than in the female5. In an allied bird, the JToplopterus armatus. the spur5 do not increase in size during the breeding-season ; bid 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, some' times with a fatal result. Thus also they drive away’ other enemies.17 The season of love is that of battle ; but the male5 of some birds, as of the game-fowl and ruff, and eve11 the young males of the wild turkey and grouse,18 aff ready to fight whenever they meet. The presence the female is the teterrima belli causa. The Bengal1 16 for the Egyptian goose, see Mncgillivray, ‘British Birds,’ vol. ,v' p. 039. For Pleetropterus, ‘ Livingstone's Travels,’ p. 254. For l’idr raedea. B robin s ‘ Thierleben,’ B. iv. s. 740. See also on this bird Aw rll‘ - Voyages dans I’Amdrique merid.' tom. iv. 1809, p. 179, 253. 17 See, on our peewit, Mr. It. Carr in ‘ Land and Water,’ Aug. SyJ 1868, p. 46. In regard to Lobivanellus, see Jerdou’s ‘Birds of Indto vol. iii. p. 647, and Gould’s ‘Handbook of Birds of Australia,’ VolA1, p. 220. For the Ilolopterus, see Mr. Allen in the ‘ Ibis,’ vol. v. IS®3’ p. 156. 18 Audubon, ‘ Ornitli. Biography,’ vol. ii. p. 492 ; vol. i. p. 4-13. LAW OF BATTLE. 49 C«AP. '• XIII. ^abi , 'Oos make the pretty little males of the amadavat Wstretda amandava ) fight together by placing three small cages in a row, with a female in the middle ; a ter a little time the two males are turned loose, and ‘^mediately a desperate battle ensues.19 When many lnales congregate at the same appointed spot and fight |°gether, as in the case of grouse and various other they are generally attended by the females,20 p afterwards pair with the victorious combatants. mt in some cases the pairing precedes instead of suc- ceeding the combat: thus, according to Audubon,21 8everal males of the Virginian goat-sucker ( Capri - '^gus Virginianus) “ court, in a highly entertaining „ ^aQner, the female, and no sooner has she made her (l e than her approved gives chase to all intruders, •md drives them beyond his dominions.” Generally 16 males try with all their power to drive away or kill u 61r rivals before they pair. It does not, however, appear that the females invariably prefer the victorious lcl es. I jlavc indeed been assured by M. W. Kowa- revsk • - - a^'sky that the female capercailzie sometimes steals th a young male who has not dared to enter Q e ai’eQa with the older cocks ; in the same manner as ^Ccasionaiiy happens with the does of the red-deer in sii 1 (I* ^ hen two males contend in presence of a ^ e female, the victor, no doubt, commonly gains his Mu Blyth, < Land mid Water,’ 1SG7, p. 212. n ■ , ■ j leuiu huh vvaier, 10 p, 34010 lardson, on Tetmo umbelluB, ‘ Fauna Bor. Amcr. : Birds,’ 1831, Canp. ' .,L- Ll°yd, 1 Game Birds of Sweden,’ 1S07, p. 22, 79, on the - rcauzie and black-. B :-cock. _ _ Breluri, however, asserts ‘Thierleben,’ &c., the p,S,' 352i that in Germany the 'grey-hens do not generally attend a °f the 'black-cocks, but this is an exception to the common is WP0SsibIy the hens may lie hidden in the surrounding bushes, _ as oth,„. J'Vn to bo the case with the grey-hens in Scandinavia, and with er sPecier -- ” • 13 in N. America. -i . , , . ■ America. ’mthological Biography,’ vol. ii. p. 275. V°V II. E 50 SEXUAL SELECTION : BIKDS. Part H- desire ; but some of these battles are caused by wander- ing males trying to distract the peace of an already mated pair.22 Even with the most pugnacious species it is probable that the pairing does not depend exclusively on th® 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 tl>(; females. The males also endeavour to charm or ex- cite 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 ar® invariably compelled to yield to the victorious malt'8. It is more probable that the females are excited, either before or after the conflict, by certain males, and thus unconsciously prefer them. In the case of Tdrao uW lettus, a good observer23 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 J “have never been able to find a maimed hero, aDu “ seldom more than a broken feather.” I shall hav® to recur to this subject, but I may here add that with the Tetrao cupido of the United States, about a score males assemble at a particular spot, and strutting abo®* make the whole air resound with their extraordinary noises. At the first answer from a female the mal®5 begin to fight furiously, and the weaker give way ; but then, according to Audubon, both the victors and van- quished search for the female, so that the females must 2i Brehm, ‘ Thierleben,’ &c., B. iv. 1867, p. 990. Audubon, ‘ Ornitt’* Biography,’ vol. ii. p. 492. 25 ‘ Land and Water,’ July 25tli, 1868, p. 14. VOCAL MUSIC. 51 Cn«“. XIII, Bitber then exert a choice, or the battle must be re- Jwed. So, again, with one of the Field-starlings of he United States ( Sturnella ludoviciana ) the males ftngage in fierce conflicts, “ but at the sight of a female 1 ley all fly after her, as if mad.” 24 ^ 0e«Z and instrumental Music. — With birds the voice eiv°s to express various emotions, such as distress, fear, "U8eb triumph, or mere happiness, it is apparently Retimes used to excite terror, as with the hissing '°lse made by some nestling-birds. Audubon25 relates ^ at a night-heron ( Ardea nycticorax, Linn.) which he ' l’1 tame, used to hide itself when a cat approached, then “ suddenly start up uttering one of the most <( r%htful cries, apparently enjoying the cats alarm and flight.” The common domestic cock clucks to 6 hen, and the hen to her chickens, when a dainty