: ..V. ..,.'.; . ..:■ '-fcT'Tfa, .It ,r.,.. f I I I I 6 5 QtCtdM^ CD UJ o CD CD cr LU hH JT • 00 !r- a jO * l * N H ^ THE DESCENT OE MAN, AND SELECTION IN RELATION TO SEX. BY CHARLES DARWIN, M. A., F. R. S., Etc. WITH ILLUSTRATIONS. IN TWO VOLUMES.— Vol. I. NEW YORK: D. APPLETON AND COMPANY, 549 & 551 BROADWAY. 1872. CONTENTS. Introduction, . Dage 1 PART I. THE DESCENT OR ORIGIN OF MAN. CHAPTER I. THE EVIDENCE OF THE DESCENT OF MAN FROM SOME LOWER FORM. Nature of the Evidence bearing on the Origin of Man. — Homologous struct- ures in Man and the Lower Animals. — Miscellaneous Points of Corre- spondence.— Development. — Rudimentary Structures, Muscles, Sense- organs, Hair, Bones, Reproductive Organs, etc. — The Bearing of these three great Classes of Facts on the Origin of Man, . . . p. 9 CHAPTER II. COMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANIMALS. The Diiference in Mental Power "between the Highest Ape and the Lowest Savage, immense. — Certain Instincts in common. — The Emotions. — Curiosity. — Imitation. — Attention. — Memory. — Imagination. — Reason. — Progressive Improvement. — Tools anct Weapons used by Animals. — Language. — Self-Consciousness.— Sense of Beauty. — Belief in God, Spiritual Agencies, Superstitions, . . . . . . p. 33 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 conquer other less Persistent Instincts. — The Social Virtues alone re- iv CONTENTS. garded by Savages. — The Self-regarding Virtues acquired at a Later Stage of Development. — The Importance of the Judgment of the Members of the same Community on Conduct. — Transmission of Moral Tendencies. — Summary, page 67 CHAPTER IV. ON THE MANNER OF DEVELOPMENT OF MAN FROM SOME LOWER FORM. Variability of Body and Mind in Man. — Inheritance. — Causes of Varia- bility.— 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. — Eeversion. — Cor- related Variation. — Eate of Increase. — Checks to Increase. — Natural Selection. — Man the most Dominant Animal in the World. — Impor- tance of his Corporeal Structure. — The Causes which have led to his becoming erect. — Consequent Changes of Structure. — Decrease in Size of the Canine Teeth. — Increased Size and Altered Shape of the Skull. — Nakedness. — Absence of a Tail. — Defenceless Condition of Man, p. 103 CHAPTEE V. ON THE DEVELOPMENT OF THE INTELLECTUAL AND MORAL FACULTIES DURING PRIMEVAL AND CIVILIZED TIMES. The Advancement of the Intellectual Powers through Natural Selection. — Importance of Imitation. — Social and Moral Faculties. — Their Develop- ment within the Limits of the same Tribe. — Natural Selection as af- fecting Civilized Nations. — Evidence that Civilized Nations were once barbarous, p. 152 CHAPTEE VI. ON THE AFFINITIES AND GENEALOGY OF MAN. Position of Man in the Animal Series. — The Natural System genealogical. — Adaptive Characters of Slight Value. — Various Small Points of Ee- semblance between Man and the Quadrumana. — Eank of Man in tho Natural System. — Birthplace and Antiquity of Man. — Absence of Fossil Connecting-links. — Lower Stages in the Genealogy of Man, as inferred, firstly from his Affinities and secondly from his Structure. — Early Androgynous Condition of the Vertebrata. — Conclusion, p. 178 CONTENTS. V CHAPTER VII. ON THE RACES OF MAN. The Nature and Value of Specific Characters.— Application to the Eaces of Man. — Arguments in favor of, and opposed to, ranking the So- called Eaces of Man as Distinct Species. — Sub-species. — Monogenists and Polygenists. — Convergence of Character. — Numerous Points of Eesemblance in Body and Mind between the most Distinct Eaces of Man. — The State of Man when he first spread over the Earth. — Each Eace not descended from a Single Pair.— The Extinction of Eaces. — The Formation of Eaces. — The Effects of Cx*ossing. — Slight Influence • of the Direct Action of the Conditions of Life. — Slight or no Influence of Natural Selection. — Sexual Selection, .... page 206 PART II. sexual selection: CHAPTEE VIII. PRINCIPLES OF SEXUAL SELECTION. % Secondary Sexual Characters. — Sexual Selection. — Manner of Action. — Excess of Males. — Polygamy. — The Male alone generally modified through Sexual Selection. — Eagerness of the Male. — Variability of the Male. — Choice exerted by the Female. — Sexual compared with Natural Selection. — Inheritance, at Corresponding Periods of Life, at Corresponding Seasons of the Year, and as limited by Sex. — Eelations 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 Limitation of the Numbers of the two Sexes through Natural Selection, ........ p. 245 CHAPTEE IX. SECONDARY SEXUAL CHARACTERS IN THE LOWER CLASSES OF THE ANIMAL KINGDOM. These Characters absent in the Lowest Classes. — Brilliant Colors. — Mol- lusca. — Annelids. — Crustacea, Secondary Sexual Characters strongly developed ; Dimorphism ; Color ; Characters not acquired before Maturity. — Spidei-s, Sexual Colors of; Stridulation by the Males. — Myiiapoda, p. 312 vi CONTENTS. 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 under- stood.— Difference in Size between the Sexes. — Thysanura. — Diptera. — Hemiptera. — Homoptera, Musical Powers possessed by the Males alone. — Orthoptcra, Musical Instruments of the Males, much diversi- fied in Structure ; Pugnacity ; Colors. — Neuroptera, Sexual Differences in Color. — Hymenoptera, Pugnacity and Colors. — Coleoptera, Colors ; furnished* with Great Horns, apparently as an Ornament ; Battles ; Stridulating Organs generally common to Both Sexes, . page 331 CHAPTER XI. insects, continued. — order lepidoftera. Courtship of Butterflies. — Battles. — Ticking Noise. — Colors common to Both Sexes, or more brilliant in the Males. — Examples. — Not due to the Direct Action of the Conditions of Life. — Colors adapted for Pro- tection.— Colors of Moths. — Display. — Perceptive Powers of the Lepi- doptera. — Variability. — Causes of the Difference in Color between the Males and Females. — Mimicry, Female Butterflies more brilliantly colored than the Males. — Bright Colors of Caterpillars. — Summary and Concluding Remarks on the Secondary ^exual Characters of In- sects.— Birds and Insects compared, . .... p. 374 INTRODUCTION The nature of the following work will be 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 Yogt ven- tures to say Jn his address as President of the National Institution of Geneva (1869), "personne, en Europe au moins, n'ose plus soutenir la creation independante et de toutes pieces, des especes," it is manifest that at 2 INTRODUCTION. least a large number of naturalists m;:st admit that species are the modified descendants of other species ; and this especially holds good with the younger and rising naturalists. The greater number accept the agency of natural selection ; though some urge, whether with justice the future must decide, that I have greatly overrated its importance. Of the older and honored 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 struct ure, 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 favor of the principle of gradual evolution. The strong sup- INTRODUCTION. 3 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 preexisting form ; secondly, the manner of his development ; and thirdly, the value of the differ- ences between the so-called races of man. As I shall confine myself to these points, it will not be 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 man has recently been demonstrated by the labors of a host of eminent men, beginning with M. Eoucher de 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 ha\ e occasion to do more than to allude to the amount of difference between man and the anthropomorphous apes ; for Prof. Huxley, in the opinion of most competent judges, has conclu- sively shown 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 me interesting, I thought that they might interest 4 INTRODUCTION. others. It has often and confidently been asserted, that man's origin can never be known : but ignorance more frequently begets confidence than does knowledge : it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science. The conclusion that man is the co-descendant with other species of some ancient, lower, and extinct form, is not in any degree new. La- marck long ago came to this conclusion, which has lately been maintained by several eminent naturalists and philosophers ; for instance, by Wallace, Huxley, Lyell, Vogt, Lubbock, Biichner, Rolle, etc.,1 and especially by Hackel. This last naturalist, besides his great work, 4 Generelle Morphologie' (1866), has recently (1868, with a second edit. 1870) published his ' JNTatiirliche Schopfungsgeschichte,' in which he fully discusses the genealogy of man. If this work had appeared before 1 As the works of the first-named authors are so well known, I need not give the titles ; but, as those of the latter are less well known in England, I will give them : ' Sechs Vorlesungen uber die Darwin'sche Theorie:' zwiete Auflage, 1868, von Dr. L. Biichner; translated into French under the title 'Conferences sur la Theorie Darwinienne,' 1869. 1 Der Mensch, im Lichte der Darwin'sche Lehre,' 1865, von Dr. F. Rolle. 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 (' An- nuario della Soc. d. Nat.,' Modena, 1867, p. 81) a very curious paper on rudimentary characters, as bearing on the origin of man. Another work has (1869) been published by Dr. Barrago Francesco, bearing in Italian the title of " Man, made in the image of God, was also made in the image of the ape." INTRODUCTION. 5 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. Ilackel'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 probable that sexual selection has played an important part in differentiating the races of man ; but in my ' Origin of Species ' (first edition, p. 199) I contented myself by merely alluding to this belief. When I came to apply this view to man, I found it indispensable to treat the whole subject in full detail.3 Consequently the second part of the present work, treating of sexual selection, 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 and the lower animals. My attention was called to this subject many years ago by Sir Charles Bell's admirable 2 Prof. Hiickel is the sole author who, since the publication of the ' Origin,' has discussed, in his various works, in a very able manner, the subject of sexual selection, and has seen its full importance. G INTRODUCTION. work. This illustrious anatomist maintains that man is endowed with certain muscles solely for the sake of expressing his emotions. As this view is obviously- opposed to the belief that man is descended from some other and lower form, it was necessary for me to con- sider it. I likewise wished to ascertain how far the emotions are expressed in the same -manner by the dif- ferent races of man. But, owing to the length of the present work, I have thought it better to reserve my essay, which is partially completed, for separate pub- lication. PART I. THE DESCENT OR ORIGIN OF MAN THE DESCENT OF MA]ST. CHAPTER I. THE EVIDENCE OF THE DESCENT OF MAN FROM SOME LOWER FORM. Nature of the Evidence bearing on the Origin of Man. — Homologous struct- ures in Man and the Lower Animals. — Miscellaneous Points of Corre- spondence.— Development. — Rudimentary Structures, Muscles, Sense- organs, Hair, Bones, Reproductive Organs, etc. — The Bearing of these three great Classes of Facts on the Origin of Man. He who wishes to decide whether man is the modified descendant of some preexisting form, would probably first inquire whether man varies, however slightly, in bodily structure and in mental faculties ; and if so, whether the variations are transmitted to his offspring in accordance with the laws which prevail with the lower animals ; such as that of the transmission of characters to the same age or sex. Again, are the variations the result, as far as our ignorance permits us to judge, of the same general causes, and are they governed by the same general laws, as in the ease of other organisms ; for instance, by correlation, the inherited effects of use and disuse; etc. ? Is man subject to similar malconformations, the result of arrested develop- ment, of reduplication of parts, etc., and does he display in any of his anomalies reversion to some former and an- cient type of structure? It might also naturally be in- 10 THE DESCENT OF MAN. [Part I. quired whether man, like so many other animals, has given rise to varieties and sub-races, differing hut slightly from each other, or to races differing so much that they must be classed as doubtful species ? How are such races distrib- uted 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. The inquirer 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 con- sequently 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 ap- plied, encroach on and replace each other, so that some finally become extinct ? We shall see that all these ques- tions, as indeed is obvious in respect to most of them, must be answered in the affirmative, in the same manner as with the lower animals. But the several considerations just referred to may be conveniently deferred for a time ; and we will first see how far the bodily structure of man shows traces, more or less plain, of his descent from some lower form. In the two succeeding chapters the mental powers of man, in comparison with those of the lower animals, will be considered. The Bodily Structure of 3Ian. — 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 important of all the organs, follows the same law, as shown by Huxley and other anatomists. Bischoff,1 who is a hostile witness, admits that every chief fissure and fold in the brain of ' Grosshirnwindungen des Menchen,' 1868, s. 96. Chap. I.] HOMOLOGICAL STRUCTURE. H man has its analogy in that of the orang ; but he adds that at no period of development do their brains perfectly agree; nor could this be expected, for otherwise their mental powers would have been the same. Vulpian2 re- marks: "Les differences reelles qui existent entre'Pence- phale de l'homme et celurdes singes superieurs, sont bien minimes. II ne faut pas se faire d'illusions a cet egard. L'homme est bien plus pres des singes anthropomorphes par les caracteres anatomiques de son cerveau que ceux-ci ne le sont non-seulement des autres mammiferes, mais memes de certains quadrumanes, des guenons et des ma- caques." But it would be superfluous here to give fur- ther details on the correspondence between man and the higher mammals 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 struct- ure, by which this correspondence or relationship is well shown. Man is liable to receive from the lower animals, and to communicate to them, certain diseases, as hydrophobic, variola, the glanders, etc. ; and this fact proves the close similarity of their tissues and blood, both in minute struct- ure and composition, far more plainly than does their com- parison under the best microscope, or by the aid of the best chemical analysis. Monkeys are liable to many of the same non-contagious diseases as we are ; thus Reng- ger,3.who carefully observed for a long time the Cebus Azarce in its native land, found it liable to catarrh, with the usual symptoms, and which when often recurrent led to consumption. These monkeys suffered also from apo plexy, inflammation of the bowels, and cataract in the eye. 2 'Le?. sur la Phys.' 1866, p. 890, as quoted by M. Dally, ' L'Ordre des Primates et le Transformisme,' 1868, p. 29. a ' Naturgeschichte der Siiugethiere von Paraguay,' 1 830, s. 50. 12 * THE DESCENT OF MAN. [Part I. The younger ones when shedding their milk-teeth often died from fever. Medicines produced the same effect on them as on us. Many kinds of monkeys have a strong taste for tea, coffee, and spirituous liquors : they will also, as I have myself seen, smoke tobacco with pleasure. Brehm asserts that the natives of northeastern 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 behavior and strange grimaces. On the following morning they were very cross and dismal ; they held their aching heads with both hands and wore a most pitiable expression ; when beer or wine was offered them, they turned away with disgust, but relished the juice of lemons.4 An Amer- ican monkey, an Ateles, after getting drunk on brandy, would never touch it again, and thus was wiser than many men. These trifling facts prove how similar the nerves of taste must be in monkeys and man, and how similarly their whole nervous system is affected. Man is infested with internal parasites, sometimes causing fatal effects, and is plagued by external parasites, 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 mysterious law, which causes certain normal processes, such as gestation, as well as the maturation and duration of various diseases, to follow lunar periods.6 His wounds are repaired by the same j)rocess of healing ; and the stumps left after the 4 Brehm, ' Thierleben,' B. i. 1864, s. 75, 86. On the Ateles, s. 105. For other analogous statements, see s. 25, 107. 5 With respect to insects see Dr. Laycock ' On a General Law of Vital Periodicity,' British Association, 1842. Dr. Macculloch, 'Silliman's North American Journal of Science,' vol. xvii. p. 305, has seen a dog suf fering from tertian ague. hap. I.] HOMOLOGICAL STRUCTURE. 13 amputation of his limbs occasionally possess, especially during an early embryonic period, some power of regen- eration, as in the lowest animals.8 The whole process of that most important function, the reproduction of the species, is strikingly the same in all mammals, from the first act of courtship by the male 7 to the birth and nurturing of the young. Monkeys are born in almost as helpless a condition as our own infants ; and in certain genera the young differ fully as much in appearance from the adults, as do our children from their full-grown parents.8 It has been urged by some writers as an important distinction, that with man the young arrive at maturity at a much later age than with any other animal : but if we look to the races of mankind which inhabit tropical countries the difference is not great, for the orang is believed not to be adult till the age of from ten to fifteen years.9 Man differs from woman in size, bodily strength, hairyness, etc., 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 cor- 6 1 have given the evidence on this head in my ' Variation of Animals and Plants under Domestication,' vol. ii. p. 15. 7 " Mares e diversis generibus Quadrumanorum sine dubio dignoscunt feminas humanas a maribus. Primum, credo, odoratu, postea aspectu. Mr. Youatt, qui diu in Hortis Zoologicis (Bestiariis) medicus animalium erat, vir in rebus observandis cautus et sagax, hoc mihi certissime pro- bavit, et curatores ejusdem loci et alii e ministris confirmaverunt. Sir Andrew Smith et Brehm notabant idem in Cynocephalo. Ulustrissimus Cuvier etiam narrat multa de hac re qua ut opinor nihil turpius potest indicari inter omnia hominibus et Quadrumanis communia. Narrat enira Cynocephalum quendam in furorem incidere aspectu feminarum aliquarum, sed nequaquam accendi tanto furore ab omnibus. Semper eligebat ju- niores, et dignoscebat in turba, et advocabat voce gestuque." 8 This remark is made with respect to Cynocephalus and the anthropo- morphous apes by Geonroy Saint-IIilaire and F. Cuvier, • Hist. Nat. des Mammiferes, torn. i. 1824. 8 Huxley, 'Man's Place in Nature,' 1863, p. 34. 14 THE DESCENT OF MAN. [Part I. respondence in general structure, in the minute structure of the tissues, in chemical composition, and in constitution, between man and the higher animals, especially the an- thropomorphous 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 branchiae 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 fundamental form." It is, says Prof. Huxley,10 " quite in the latter stages of de- velopment that the young human being presents marked differences from the young ape, while the latter departs as much from the dog in its developments, as the man does. Startling as this last assertion may appear to be, it is de- monstrably 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, carefully copied from two works of undoubted accuracy.11 10 ' Man's Place in Nature,' 1863, p. 67. 11 The human embryo (upper fig.) is from Ecker, 'Icones 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 Bi- Bchoff, ' Entwicklungsgcschichte des Hunde-Eies,' 1845, tab. xi. fig. 42 b. This drawing is five times magnified, the embryo being 25 days old. The Chap. I.] EMBRYONIC DEVELOPMENT. 15 Fig. 1.— Upper figure human embryo, from Ecker. Lower figure that of a dog, from Bischoff. a. Fore-brain, cerebral hemispheres, etc. b. Mid-brain, corpora quadrteemina. c. Hind-brain, cerebellum, medulla oblongata. d. Eye. c. Ear. f. First visceral arch. g. Second visceral arch. H. Vertebral columns and muscles in process of development. L. Tail or os coccyx. 16 THE DESCENT OF MAN. [Part I. After the foregoing statements made by such high authorities, it would be superfluous on my part to give a number of borrowed details, showing that the embryo of man closely resembles that of other mammals. It may, however, be added that the human embryo likewise resem- bles in various points of structure certain low forms when adult. For instance, the heart at first exists as a simple pulsating vessel ; the excreta are voided through a cloacal passage ; and the os coccyx projects like a true tail, " ex- tending considerably beyond the rudimentary legs." 12 In the embryos of all air-breathing vertebrates, certain glands called the corpora Wolffiana, correspond with and act like the kidneys of mature fishes.13 Even at a later embryo- nic period, some striking resemblances between man and the lower animals may be observed. Bischoff says that the convolutions of the brain in a human foetus at the end of the seventh month reach about the same stage of de- velopment as in a baboon when adult.14 The great toe, as Prof. Owen remarks,16 " which forms the fulcrum when standing or walking, is perhaps the most characteristic peculiarity in the human structure ; " but in an embryo, about an inch in length, Prof. Wyman 16 found that the great toe was shorter than the others, and, instead of be- ing parallel to them, projected at an angle from the side af the foot, thus corresponding with the permanent condi- internal viscera have been omitted, and the uterine appendages 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 waa taken. Hackel has also given analogous drawings in his 'Schopfungs- geschichte.' 12 Prof. Wyman in ' Proc. of American Acad, of Sciences,' vol. iv. 1860, p. 17. 13 Owen, 'Anatomy of Vetebrates,' vol. i. p. 533 14 ' Die Grosshirnwindungen des Menschen,' 1868, s. 95 15 ' Anatomy of Vertebrates,' vol. ii. p. 553. ls 'Proc. Soc. Nat. Hist.' Boston, 1863, voL ix. p. 186. Chap I.] RUDIMENTS. 17 tion of this part in the quadrumana." I will conclude with a quotation from Huxley,17 who,- after asking, does man originate in a different wray from a dog, bird, frog, or fish ? says, " the reply is .not doubtful for a moment ; without question, the mode of origin and the early stages of the development of man are identical with those of the ani- mals "immediately below him in the scale : without a cloubt in these respects, he is far nearer to apes, than the apes are to the dog." Rudiments, — This subject, though not intrinsically more important than the last two, will for several reasons be here treated with more fulness.18 Not one of the higher animals can be named which does not bear some part in a rudimentary condition ; and man forms no ex- ception to the rule. Rudimentary organs must be dis- tinguished from those that are nascent ; though in some cases the distinction is not easy. The former are either absolutely useless, such as the marnmoe of male quad- rupeds, or the incisor teeth of ruminants which never cut through the gums ; or they are of such slight service to their present possessors, that we cannot suppose that they were developed under the conditions which now exisf. Organs in this latter state are not strictly rudimentary, but they are tending in this direction. Nascent organs, on the other hand, though not fully developed, are of high service to their possessors, and are capable of further de- velopment. Rudimentary organs are eminently variable ; and this is partly intelligible, as they are useless or nearly 17 ' Man's Place in Nature,' p. 65. 18 I had written a rough copy of this chapter before reading a valu- able paper, " Caratteri rudimentali in ordine all' origine del uorno" ('An- nuario della Soc. d. Nat.,' Modena, 1807, p. 81), by G. Canestrini, to which paper I am considerably indebted. Hiickel has given admirable- discussions on this whole subject, under the title of Dystcleology, in hia * Generelle Morphologie ' and ' Schopfungsgeschichte.' . 2 18 THE DESCENT OF MAN. [Part L useless, arid consequently are no longer subjected to nat- ural selection. They often become wholly suppressed. When this occurs, they are nevertheless liable to occa- sional reappearance through reversion ; and this is a cir- cumstance well worthy of attention. Disuse at that period of life, when an organ is chiefly used, and this is generally during maturity, together wTitb inheritance at a corresponding period of life, seem to have been the chief agents in causing organs to become rudi- mentary. The term " disuse " does not relate merely to the lessened action of muscles, but includes a diminished flow of blood to a part or organ, from being subjected to fewer alternations of pressure, or from becoming in any way less habitually active. Rudiments, however, may occur in one sex of parts normally present in the other sex ; and such rudiments, as we shall hereafter see, have often originated in a distinct manner. In some cases or- gans have been reduced by means of natural selection, from having become injurious to the species under changed habits of life. The process of reduction is probably often aided through the two principles of compensation and economy of growth; but the later stages of reduction, alter disuse has done all that can fairly be attributed to it, and when the saving to be effected by the economy of growth would be ve^y small,19 are difficult to understand. The final and complete sivppression of a part, already use- less and much reduced in size, in which case neither com- pensation nor economy can come into play, is perhaps in- telligible by the aid of the hypothesis of pangenesis, and apparently in no other way. But as the whole subject of rudimentary organs has been fully discussed and illustrated in my former works,20 1 need here say no more on this head. 19 Some good criticisms on this subject have been given by Messrs. Murie and Mivart, in 'Transact. Zoolog. Soc' 1869, vol. vii. p. 92. »o < Variation of Animals and Plants under Domestication,' vol. ii. pp. 817 and 397. See also c Origin of Species,' 5th edit. p. 535. Chip. I.] RUDIMENTS. 19 Rudiments of various muscles have b^en observed in many parts of the human body ; 21 and not a few muscles, which are regularly present in some of the lower animals can occasionally be detected in man in a greatly reduced condition. Every one must have noticed the power which many animals, especially horses, possess of moving or twitching their skin ; and this is effected by the pannicu- lus carnosus. Remnants of this muscle in an efficient state are found in various parts of our bodies ; for in- stance, on the forehead, by which the eyebrows are raised. The platysma myoides, which is well developed on the neck, belongs .to this system, but cannot.be voluntarily brought into action. Pro£ Turner, of Edinburgh, has occasionally detected, as he informs me, muscular fasciculi in five different situations, namely, in the axillae, near the scapulae, etc., all of which must be referred to the system of the panniculus. He has also shown 22 that the musculus sternalls or sternalis brutorum, which is not an extension of the rectus abdominalis, but is closely allied to the panniculus, occurred in the proportion of about three per cent, in upward of six hundred bodies : he adds, that this muscle affords " an excellent illustration of the statement that occasional and rudimentary structures are especially liable to variation in arrangement." Some few persons have the power of contracting the 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 21 For instance, M. Richard (' Annales-des Sciences Nat.' 3d series, Zoolog. 1852, torn, xviii. p. 13) describes and figures rudiments of what he calls the "muscle pedicux de la main," which he says is sometimes "infiniment petit." Another muscle, called "le tibial posterieur," is gen- erally quite absent in the hand, but appears from time to time in a more or less rudimentary condition. 59 Prof. W. Turner, 'Proc. Royal Soc. Edinburgh,' 1866-67, p. 65. 20 THE DESCENT OF MAN. [Part I. 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 children, possess the same power to the same unusual degree. This family became divided eight generations ago into two branches; so that the head of the above-mentioned branch is cousin in the seventh degree to the head of the other branch. This distant cousin resides in another part of France, and, or being asked whether he possessed the same faculty, im mediately exhibited his power. This case offers a good il lustration 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 forward, and another who could draw them backward ; 23 and, from what one of these persons told me, it is probable that most of us, by often touching our ears and thus directing our attention toward them, could by repeated trials recover some power of movement. The faculty of erecting the ears and of directing them to different points of the com- pass, is no doubt of the highest service to many animals, as they thus perceive the point of danger ; but I have never heard of a man who possessed the least power of erecting his ears — the one movement which might be of use to him. The whole, external shell of the ear may be considered a rudiment, together with the various folds and prominences 23 Canestrini quotes Hyrt. (' Annuario della Soc. dei Naturalisti,' Modern, 1867, p. 97) to the same effect. Chap. I.] RUDIMENTS. 21 (helix and anti-helix, tragus and anti-tragus, *,tc.) which in the lower animals strengthen and support the ear when erect, without adding much to its weight. Some authors, however, suppose that the cartilage of the shell serves to transmit vibrations to the acoustic nerve ; but Mr. Toyn- bee,24 after collecting all the known evidence on this head, concludes that the external shell is of no distinct use. The ears of the chimpanzee and orang are curiously like those of man, and I am assured by the keepers in the Zoo- logical Gardens that these animals never move or erect them ; so that they are in an equally rudimentary condi- tion, as far as function is concerned, as in man. "Why these animals, as well as the progenitors of man, should have lost the power of erecting their ears we cannot say. It may be, though I am not quite satisfied with this view, that owing to their arboreal habits and great strength they were but little exposed to danger, and so during a length- ened period moved their ears but little, and thus gradually lost the power of moving them. This would be a parallel case with that of those large and heavy birds, which from inhabiting oceanic islands have not been exposed to the attacks of beasts of prey, and have consequently lost the power of using their wings for flight. The celebrated sculptor, Mr. Woolner, informs me of one little peculiarity in the external ear, which he has often observed both in men and women, and of which he perceived the full signification: His attention was first called to the subject while at work on his figure of Puck, to which he had given pointed ears. He was thus led to examine the ears of various monkeys, and subsequently more carefully those of man. The peculiarity consists in a little blunt point, projecting from the inwardly-folded margin, or helix. Mr. Woolner made an exact model of one such case, and has sent me the accompanying draw- 24 ' The Diseases of the Ear,' by J. Toynbee, F. R. S., 1860, p. 12. 22 THE DESCENT OF MAN. [Tart I. ing. (Fig. 2.) These points not only project inward, but often a little outward, so that they are visible when the head is viewed from directly in front or behind. They are variable in size and somewhat in po- sition, standing either a little high- er or lower; and they sometimes occur in one ear and not on the other. Now the meaning of these Br m 111 1m ProJccti°ns is notj I think, doubt- ful; but it may be thought that they offer too trifling a character to be worth notice. This thought, however, is as false as it is natural. Every character, however slight, Fig. 2.— Human Ear, modelled must be the result of some definite and drawn by Mr. Woolner. , . „ . a. The projecting point. cause ; and if it occurs m many individuals deserves consideration. The helix obviously consists of the extreme margin of the ear folded inward ; and this folding appears to be in some manner connected with the whole external ear, being per- manently pressed backward. In many monkeys, which do not stand high in the order, as baboons and some species of macacus,25 the upper portion of the ear is slightly pointed, and the margin is not at all folded in- ward ; but if the margin were to be thus folded, a slight point would necessarily project inward and probably a little outward. This could actually be observed in a specimen of the Ateles beehebuth in the Zoological Gar- dens ; and we may safely conclude that it is a similar structure — a vestige of formerly-pointed ears — which oc-' casionally reappears in man. The nictitating membrane, or third eyelid, with its 85 See also some remarks, and the drawings of the ears of the Lemu, roidea, in Messrs. Murie and Mivart's excellent paper in ' Transact. Zoo- .og. Soc' vol. vii. 1869, pp. 6 and 90. Chap. I.] RUDIMENTS. 23 accessory muscles and other structures, is especially well developed in birds, and is of much functional importance to them, as it can be rapidly drawn across the whole eye- ball. It is found in some reptiles and amphibians, and in certain fishes, as in sharks. It is fairly well developed in the two lower divisions of the mammalian series, namely, in the monotremata and marsupials, and in some few of the higher mammals, as in the walrus. But in man, the quadrumana, and most other mammals, it exists, as is ad- mitted by all anatomists, as a mere rudiment, called the semilunar fold.20 The sense of smell is of the highest importance to the greater number of mammals — to some, as the ruminants, in warning them of danger ; to others, as the carnivora, in finding their prey ; to others, as the wild-boar, for both purposes combined. But the sense of smell is of ex- tremely slight service, if any, even to savages, in whom it is generally more highly developed than in the civilized races. It does not warn them of danger, nor guide them • to their food; nor does it prevent the Esquimaux from sleeping in the most fetid atmosphere, nor many savages from eating half-putrid meat. Those who believe in the- principle of gradual evolution, will not readily admit that this sense in its present state was originally acquired by man, as he now exists. No doubt he inherits the power in an enfeebled and so far rudimentary condition, from some early progenitor, to whom it was highly serviceable and by whom it was continually used. We can thus perhaps understand how it is, as Dr. Maudsley has truly 28 Miiller's 'Elements of Physiology,' Eng. translat., 1842, vol. ii. p. 1117. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 260; ibid, on the Walrus, ' Proc. Zoolog. Soc.' November 8, 1854. See also R. Knox, Great Artists and Anatomists,' p. 106. This rudiment apparently is Bomewhat larger in Negroes and Australians than in Europeans, see Carl Vogt, • Lectures on Man,' Eng. translat. p. 129. 24 THE DESCENT OF MAN". [Part I. remarked,27 that the sense of smell in man " is singularly effective in recalling vividly the ideas and images of for- gotten scenes and places ; " for we see in those animals, which have this sense highly developed, such as dogs and horses, that old recollections of persons and places are strongly associated with their odor. Man differs conspicuously from all the other Primates in being almost naked. But a few short, straggling hairs are found over the greater part of the body in the male sex, and fine down on that of the female sex. In individ- uals belonging to the same race these hairs are highly variable, not only in abundance, but likewise in position : thus the shoulders in some Europeans are quite naked, while in others they bear thick tufts of hair.28 There can be little doubt that the hairs thus scattered over the body are the rudiments of the uniform hairy coat of the lower animals. This view is rendered all the more probable, as it is known that line, short, and pale-colored hairs on the limbs and other parts of the body occasionally become developed into " thickset, long, and rather coarse dark hairs," when abnormally nourished near old-standing in- flamed surfaces.29 I am informed by Mr. Paget that persons belonging to the same family often have a few hairs in their eye- brows much longer than the others ; so that this slight peculiarity seems to be inherited. These hairs apparently represent the vibrissa?, which are used as organs of toucli by many of the lower animals. In a young chimpanzee I observed that a few upright, rather long, hairs projected 27 'The Physiology and Pathology of Mind,' 2d edit. 1868, p. 134. 28 Eschricht, Ueber die Eichtungder Haare am menschlichen Korp er, ' M tiller's Archiv fur Anat. und Phys.' 1837, s. 47. I shall often have to refer to this very curious paper. 85 Paget, 'Lectures on Surgical Pathology,' 1S53, vol. i. p. 71. Chap. I.] RUDIMENTS. 25 above the eyes, where the true eyebrows, if present, would have stood. The fine wool-like hair, or so-called lanugo, with which the human foetus during the sixth month is thickly cov- ered, offers a more curious case. It is first developed during the fifth month, on the eyebrows and face, and es- pecially round the mouth, where it is much longer than that on the head. A mustache of this kind was observed by Eschricht 30 on a female foetus ; but this is not so sur- prising a circumstance as it may at first appear, for the two sexes generally resemble each other in all external characters during an early period of growth. The direc- tion and arrangement of the hairs on all parts of the foetal body are the same as in the adult, but are subject to much variability. The whole surface, including even the fore- head and ears, is thus thickly clothed ; but it is a signifi- cant fact that the palms of the hands and the soles of the feet are quite naked, like the inferior surfaces of all four extremities in most of the lower animals. As this can hardly be an accidental coincidence, we must consider the woolly covering of the foetus to be the rudiment al repre- sentative of the first permanent coat of hair in those mammals which are born hairy. This representation is much more complete, in accordance with the usual law of embryological development, than that afforded by the straggling hairs on the body of the adult. It appears as if the posterior molar or wisdom-teeth were tending to become rudimentary in the more civilized races of man. These teeth are rather smaller than the other molars, as is likewise the case with the correspond- ing teeth in the chimpanzee and orang ; and they have only two separate fangs. They do not cut through the gums till about the seventeenth year, and I am assured by dentists that they are much more liable to decay, and 30 Eschricht, ibid. s. 40, 47. 26 THE DESCENT OF MAN. [PARr L are earlier lost, than the other teeth. It is also remark- able that they are much more liable to vary both in struct- ure and in the. period of their development than the other teeth.31 In the Melanian races, on the other hand, the wisdom-teeth are usually furnished with three separate fangs, and are generally sound : they also differ from the other molars in size less than in the Caucasian races.32 Prof. Schaaffhausen accounts for this difference between the races by " the posterior dental portion of the jaw being always shortened " in those that are civilized,33 and this shortening may, I presume, be safely attributed to civil- ized men habitually feeding on soft, cooked food, and thus using their jaws less. I am informed by Mr. Brace that it is becoming quite a common practice in the United States to remove some of the molar teeth of children, as the jaw does not grow large enough for the perfect devel- opment of the normal number. With respect to the alimentary canal, I have met with an account of only a single rudiment, namely, the vermi- form appendage of the caecum. The caecum is a branch or diverticulum of the intestine, ending in a cul-de-sac, and it is extremely long in many of the lower vegetable-feed- ing mammals. In the marsupial koala it is actually more than thrice as long as the whole body.34 It is sometimes produced into a long, gradually-tapering point, and is sometimes constricted in parts. It appears as if, in conse- quence of changed diet or habits, the caecum had become much shortened in various animals, the vermiform append- age being left as a rudiment of the shortened part. That 31 Dr. Webb, ' Teeth in Man and the Anthropoid Apes,' as quoted by Dr. C. Carter Blake in 'Anthropological Review,' July, 1867, p. 299. 32 Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 320, 321, 325. 33 « On the primitive Form of the Skull,' Eng. translat. in ' Anthro* pobgical Review,' Oct. 1868, p. 426. 34 Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 416, 434, 441. CiiAr. I.] RUDIMENTS. 27 this appendage is a rudiment, we may infer from its small size, and from the evidence which Prof. Canestrini s-6 has collected of its variability in man. It is occasionally quite absent,, or again is largely developed. The passage is sometimes completely closed for half or two-thirds of its length, with the terminal part consisting of a flattened solid expansion. In the orang this appendage is long and convoluted ; in man it arises from the end of the short caecum, and is commonly from four to five inches in length, being only about the third of an inch in diameter. Not only is it useless, but it is sometimes the cause of death, of which fact I have lately heard two instances ; this is due to small, hard bodies, such as seeds, entering the passage and causing inflammation.86 In the Quadrumana, and some other orders of mam- mals, especially in the Carnivora, there is a passage near the lower end of the humerus, called the supra-condyloid foramen, through which the great nerve of the fore-limb passes, and often the great artery. Now, in the humerus of man, as Dr. Struthers 37 and others have shown, there is generally a trace of this passage, and it is sometimes fairly well developed, being formed by a depending hook- like process of bone, completed by a band of ligament. When present the great nerve invariably passes through it, and this clearly indicates that it is the homologue and rudiment of the supra-condyloid foramen of the lower ani- mals. Prof. Turner estimates, as he informs me, that it 35 ' Annuario dellaSoc. d. Nat.' Modem, 1867, p. 94. 86 M. C. Martins (" De l'Unite Organique," in ' Revue des Deux Mondes,' June 15, 1862, p. 16), and Hackel ('Generelle Morphologie,' B. ii. s. 278), have both remarked on the singular fact of this rudiment sometimes causing death. 37 'The Lancet,' Jan. 24, 1863, p. 83. Dr. Knox, 'Great Artista and Anatomists,' p. 63. See also an important memoir on this process by Dr. Grube, m the 'Bulletin de l'Acad. Imp. de St. Pctersbourg, torn, xii 1867, p. 448. 28 THE DESCENT OF MAN. [Part I. occurs in about one per cent, of recent skeletons ; but, during ancient times, it appears to have been much more common. Mr. Bask 38 has collected the following evi- dence on this head : Prof. Broca " noticed the perforation in four and a half per cent, of the arm-bones collected in the ' Cimetiere du Sud ' at Paris ; and in the Grotto of Orrony, the contents of which are referred to the Bronze period, as many as eight humeri out of thirty-two were perforated ; but this extraordinary proportion, he thinks, might be due to the cavern having been a sort of ' family vault.' Again, M. Dupont found thirty per cent, of- per- forated bones in the caves of the Valley of the Lesse, be- longing to the Reindeer period; while M. Leguay, in a sort of dolmen at Argenteuil, observed twenty-five per cent, to be perforated ; and M. Pruner-Bey found twenty- six per cent, in the same condition in bones from Vaureal. Nor should it be left unnoticed that M. Pruner-Bey states that this condition is common in Guanche skeletons." The fact that ancient races, in this and several other cases, more frequently present structures which resemble those of the lower animals than do the modern races, is interesting:. One chief cause seems to be that ancient races stand somewhat nearer than modern races in the long line of descent to their remote animal-like progeni- tors. The os coccyx in man, though functionless as a tail, plainly represents this j)art in other vertebrate animals. At an early embryonic period it is free, and, as we have seen, projects beyond the lower extremities. In certain rare and anomalous cases it has been known, according to Isidore Geoffroy St.-Hilaire and others,39 to form a small 38 " On the Caves of Gibraltar," ' Transact. Internal. Congress of Prehist. Arch.' Third Session, 1869, p. 54. 39 Quatrefages has lately collected the evideace on this subject, Revue des Cours Scientifiques,' 1867-68, p. 625. Chap. I.] RUDIMENTS. 29 external rudiment of a tail. The os coccyx is short, usu- ally including only four vertebrae ; and these are in a rudi- mental condition, for they consist, with the exception of the basal one, of the centrum alone.40 They are furnished with some small muscles ; one of which, as I am informed by Prof. Turner, has been expressly 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 downward as the last dorsal or first lumbar vertebra ; but a thread- like structure (the filum terminale) 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 con- sists merely of the pia mater, or vascular investing mem- brane. Even in this case- the os coccyx may be said to possess a vestige of so important a structure as the spinal cord, though no longer enclosed within a bony canal. The following fact, for which I am also indebted to Prof. Turner, shows 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 ex- tremity, a similarly convoluted body. The reproductive system offers 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 on.e sex, being represented in the other *° Owen, 'On the Nature of Limbs,' 1849, p. 114 30 TIIE DESCENT OF MAN. [Part I. • by a mere rudiment. Nevertheless, the occurrence of such rudiments is as difficult to explain on the belief of the separate creation of -each species, as in the foregoing cases. Hereafter I shall have to recur to these rudiments, and shall show that their presence generally depends merely on inheritance ; namely, on parts acquired by one sex having been partially transmitted to the other. Here I will only give some instances of such rudiments. It is well known that in the males of all mammals, including man, rudi- mentary mammae exist. These, in several instances, have become well developed, and have yielded a copious supply of milk. Their essential identity in the two sexes is like- wise shown by their occasional sympathetic enlargement in both during an attack of the measles. The vesicula prostatica, which has been observed in many male mam- mals, i$ now universally acknowledged to be the homo- logue of the female uterus, together with the connected passage. It is impossible to read Leuckart's able descrip- tion of this organ, and his reasoning, without admitting the justness of his conclusion. This is especially clear in the case of those mammals in which the true female ute- rus bifurcates, for in the males of these the vesicula like- wise bifurcates.41 Some additional rudimentary structures belonging to the reproductive system might here have been adduced.42 The bearing of the three .great classes of facts now given is unmistakable. But it would be superfluous here fully to recapitulate the line of argument given in detail 41 Leuckart, in Todd's ' Cyclop, of Anat.' 1849-'52, vol. iv. p. 1415. In man this organ is only from three to six lines in length, but, like so many other rudimentary parts, it is variable in development as well as in other characters. 42 See, on this subject. Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 675, 616, ?06. Chap. I.] RUDIMENTS. 31 in my ' Origin of Species.' The homo-logical construction of the whole frame in the members of the same class is intelligible, if we admit their descent from a common pro- genitor, together with their subsequent adaptation to di- versified conditions. On any other view the similarity of pattern between the liand of a man or monkey, the foot of a horse, the flipper of a seal, the wing of a bat, etc., is ut- terly 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 variations supervening at a rather late embryonic period, and being inherited at a corresponding period, how it is that the embryos of wonderfully different forms should still retain, more or less perfectly, the struct- ure 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, etc., can at first hardly be distinguished from each other. In order to understand the existence of rudimentary organs, we have only to sup- pose that a former progenitor possessed the parts in ques- tion in a perfect state, and that under changed habits of life they became greatly reduced, either from simple dis- use, or through the natural selection of those individuals 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 con- structed on the same general model, why they pass through the same early stages of development, and why they re- tain certain rudiments in common. Consequently we ought frankly to admit their community of descent ; to take any other view, is to admit that our own structure, and that of all the animals around us, is a mere snare laid to entrap our judgment. This conclusion is greatly strength- ened, if we look to the members of the whole animal so- 82 THE DESCENT OF MAN. [Part I. ries, and consider the evidence derived from their affinities or classification, their geographical distribution, and geo- logical succession. It is only our natural prejudice, and that arrogance which made our forefathers declare that they were descended from demi-gods, which lead us to demur to this conclusion. But the time will before long: come when it will be thought wonderful that naturalists, who were well acquainted with the comparative. structure and development of man and other mammals, should have believed that each was the work of a separate act of crea- tion, v Joap. II. 1 MENTAL TOWERS. £3 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. — Imagination. — Eeason. — 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 compare 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-organized ape. The difference would, no doubt, still remain immense, even if one of the higher apes had been improved or civilized as much as a dog has been in comparison with its parent-form, the wolf or jackal. The Fuegians rank among the lowest barbarians ; but I was continually struck with surprise how closely the three na- 1 See the evidence on these points, as given by Lubbock, ' Prehistoric Times,' p. 354, etc. 84 THE DESCENT OF MAN". [Part L tives on board H. M. S. " Beagle," who had lived some years in England, and could talk a little English, resem- bled us in disposition, and in most of our mental faculties. If no organic being excepting man had possessed any men- tal power, or if his powers had been of a wholly different nature from those of the lower animals, then we should never have been able to convince ourselves that our high faculties had been gradually developed. But it can be clearly shown that there is no fundamental difference of this kind. We must also admit that there is a much wider interval in mental power between one of the lowest fishes, as a lamprey or lancelet, and one of the higher apes, than between an ape and man ; yet this immense interval is filled up by numberless gradations. Nor is the difference slight in moral disposition between a barbarian, such as the man described by the old navi- gator Byron, who dashed his child on the rocks for drop- ping a basket of sea-urchins, and a Howard or Clarkson ; and in intellect, between a savage who does not use any abstract terms, and a Newton or Shakespeare. Differences of this kind .between the highest men of the highest races and the lowest savages, are connected by the finest grada- tions. Therefore it is possible that they might pass and be developed into each other. My object in this chapter is solely to show that there is no fundamental difference between man and the higher mammals in their mental faculties. Each division of the subject might have been extended into a separate essay, but must here be treated briefly. As no classification of the mental powers has been universally accepted, I shall arrange my remarks in the order most convenient for my purpose, and will select those facts which have most struck me, with the hope that they may produce some effect on the reader. With respect to animals very low in the scale, I shall Chap. II.] MENTAL POWERS. 35 have to give some additional facts under Sexual Selection, showing that their mental powers are higher than might have been expected. The variability of the faculties in the individuals of the same species is an important point for us, and some few illustrations will here be given. But it would be superfluous to enter into many details on this head, for I have found, on frequent inquiry, 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 low- est organisms, is as hopeless an inquiry 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 ani- mals, his fundamental intuitions must be the same. Man has also some few instincts in- common, as that of self-pres- ervation, sexual love, the love of the mother for her new- born offspring, the power possessed by the latter of suck- ing, and so forth. But man, perhaps, has somewhat fewer instincts than those possessed by the animals which come next to him in the series. The orano; in the Eastern isl- ands, and the chimpanzee in Africa, build platforms, on which they sleep ; and, as both species follow the same habit, it might be argued that this was due to instinct, but we cannot feel sure that it is not the result of both animals having similar wants, and possessing similar pow- ers of reasoning. These apes, as we may assume, avoid the many poisonous fruits of the tropics, and man has no such knowledge ; but as our domestic animals, when taken to foreign lands, and when first turned out in the spring, often eat poisonous herbs, which they afterward avoid, we cannot feel sure that the apes do not learn from their own experience, or from that of their parents, what fruits to select. It is, however, certain, as we shall presently see, 36 THE DESCENT OF MAN. [Part I. that apes have an instinctive dread of serpents, and prob- ably of other dangerous animals. The fewness and the comparative simplicity of the in- stincts in the higher animals are remarkable in contrast with those of the lower animals. Cuvier maintained that instinct and intelligence stand in an inverse ratio to each other ; and some have thought that the intellectual faculties of the* higher animals have been gradually developed from their instincts. But Pouchet, in an interesting essay,2 has shown that no such inverse ratio really exists. Those insects which possess the most wonderful instincts are cerfainly the most intelligent. In the vertebrate series, the least intelligent members, namely fishes and amphibians, do not possess complex instincts ; and among mammals the ani- mal most remarkable for its instincts, namely the beaver, ►is highly intelligent, as will be admitted by every one who has read Mr. Morgan's excellent account of this animal.3 Although the first dawnings of intelligence, according to Mr. Herbert Spencer,4 have been developed through the multiplication and coordination of reflex actions, and al- though many of the simpler instincts graduate into actions of this kind, and can hardly be distinguished from them, as in the case of young animals sucking, yet the more complex instincts seem to have originated independently of intelligence. I am, however, far from wishing to deny that instinctive actions may lose their fixed and untaught character, and be replaced by others performed by the aid of the free will. On the other hand, some intelligent ac- tions— as when birds on oceanic islands first learn to avoid man — after being performed during many generations, be- come converted into instincts, and are inherited. They 2 ' L'Instinct chez les Insectes.' ' Revue d'es Deux Mondes,' Feb. 1810, p. 690. 3 ' The American Beaver and his "Works,' 1868. * ' The Principles of Psychology,' 2d edit. 1870, pp. 418-443. Chap. II.] MENTAL POWERS. 37 may then be 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 ap- pear to have been gained in a wholly different manner, through the natural selection of variations of simpler in- stinctive actions. Such variations appear to arise from the same unknown causes acting on the cerebral organiza- tion, which induce slight variations or individual differ- ences 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 interfere with each other's development. Little is known about the functions of the brain, but we can perceive that, as the intellectual powers become highly developed, the va- rious parts of the brain must be connected by the most intricate channels of intercommunication ; and. as a conse- quence each separate part would, perhaps, tend to be- come less well fitted to answer in a definite and uniform, that is instinctive, manner to particular sensations or as- sociations. I have thought this digression worth giving, because we may easily underrate the mental powers of the higher animals, and especially of man, when we compare their actions, founded on the memory of past events, on fore- sight, reason, and imagination, with exactly similar actions instinctively performed by the lower animals ; in this lat- ter ease, the capacity of performing such actions having 88 THE DESCENT OF MAN. [Part I. been gained, step by step, through the variability of the mental organs and natural selection, without any conscious intelligence on the part of the animal during each succes- sive generation. No doubt, as Mr. Wallace has argued,5 much of the intelligent work done by man is due to imita- tion, and not to reason ; but there is this great difference between his actions and many of those performed by the lower animals, namely, that man cannot, on his first trial, make, for instance, a stone hatchet or a canoe, through his power of imitation. He has to learn his work by practice ; a beaver, on the other hand, can make its dam or canal, and a bird its nest, as well, or nearly as well, the first time it tries, as when old and experienced. To return to our immediate subject : the lower animals, like man, manifestly feel pleasure and pain, happiness and misery. Happiness is never better exhibited than by young animals, such as puppies, kittens, lambs, etc., when playing together, like our own children. Even insects play together, as has been describee! by that excellent ob- server, P. Huber,6 who saw ants chasing and pretending to bite each other, like so many puppies. The fact that the lower animals are excited by the same emotions as ourselves is so well established, that it will not be necessary to weary the reader by many details. Terror acts in the same manner on them as on us, causing the muscles to tremble, the heart to palpitate, the sphincters to be relaxed, and the hair to stand on end. Suspicion, the offspring of fear, is eminently characteristic of most wild animals. Courage and timidity are extremely va- riable 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, 5 'Contributions to the Theory of Natural Selection,' 1870, p. 212. * l Recherches sur les Hoeurs des Fourmis,' 1810, p. 173. Chap, n.] MENTAL POWERS. 39 Every one knows how liable animals are to furious rage, and bow plainly tbey show it. Many anecdotes, probably true, have been published on the long-delayed and artful revenge of various animals. The accurate Render and Brehm7 state that the American and African monkeys which they kept tame, certainly revenged themselves. The love of a dog for his master is notorious ; in the agony of death he has been known to caress his master, and every one has heard of the dog suffering under vivi- section, who licked the hand of the operator ; this man, unless he had a heart of stone, must have felt remorse to the last hour of his life. As Whewell 8 lias remarked, " who that reads the touching instances of maternal affec- tion, 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 Rengger observed an American monkey (a Cebus) carefully driving away the flies which plagued her infant ; and Duvaucel saw a Hylobates washing the faces of her young ones in a stream. So intense is the grief of female monkeys for the loss of their young, that it inva- riably caused the death of certain kinds kept under con- finement by Brehm in North Africa. Orphan-monkeys were always adopted and carefully guarded by the other mon- keys, both males and females. One female baboon had so capacious a heart, that she not only adopted young mon- keys of other species, but stole young dogs and cats, which she continually carried about. Her kindness, however, did not go so far as to share her food with her adopted off- spring, at which Brehm was surprised, as his monkeys al- 7 All the following statements, given on the authority of these two naturalists, are taken from Rengger's ' Naturges. der Siiugethiere von Paraguay,' 1830, s. 41-57, and from Brehm's ' Thierleben,' B. i. s. 10-87. 8 ' Biidgewater Treatise,' p. 263. 40 THE DESCENT OF MAN. [Part I ways divided every thing quite fairly with their own young ones. An adopted kitten scratched the above-men- tioned affectionate baboon, who certainly had a fine intel- lect, for she was much astonished at being scratched, and immediately examined the kitten's feet, and without more ado bit off the claws. In the Zoological Gardens, I heard from the keeper that an old baboon (C. chaona) had adopted a Rhesus monkey ; but when a young drill and mandrill were placed in the cage, she seemed to perceive that these monkeys, though distinct species, were her nearer relatives, for she at once rejected the Rhesus and adopted both of them. The young Rhesus, as I saw, was greatly discontented at being thus rejected, and it would, like a naughty child, annoy and attack the young drill and mandrill whenever it could do so with safety , this conduct exciting great indignation in the old baboon. Monkeys will also, according to Brehm, defend their mas- ter when attacked by any one, as well as dogs to whom they are attached, from the attacks of other dogs. But we here trench on the subject of sympathy, to which I shall recur. Some of Brehm's monkevs took much de- light in teasing, in various ingenious ways, a certain old dog whom they disliked, as well as other animals. Most of the more complex emotions are common to the higher animals and ourselves. Every one has seen how jealous a dog is of his master's affection, if lavished on any other creature ; and I have observed the same fact with monkeys. This shows 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 some- thing very like modesty when begging too often for food. A great dog scorns the snarling of a little dog, and this Chap. II.] MENTAL POWERS. 41 may be called magnanimity. Several observers have stated that monkeys certainly dislike being laughed at ; and they sometimes invent imaginary offences. In the Zoologieal 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. We 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 Reng- ger, with monkeys. All animals feel wonder, and many exhibit curiosity. They sometimes suffer from this 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 toward snakes ; but their curiosity was so great that they could not desist from oc- casionally 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 coiled-up snake into the monkey-house at the Zoological Gardens, and the excitement thus caused was one of the most curious spectacles which I ever beheld. Three species of Cercopithecus were the most alarmed ; they dashed about their cages and uttered sharp signal- cries of danger, which were understood by the other monkeys. A few young monkeys and one old Anubis baboon alone took no notice of the snake. I then placed the stuffed specimen on the ground in one of the larg< r compartments. After a time all the monkeys collected round it in a large circle, and, staring intently, presented 3 i2 THE DESCENT OF MAN. [Part I. a most ludicrous appearance. They became extremely nervous ; so that when a wooden ball, with which they were familiar as a plaything, was accidentally moved in the straw, under which it was partly hidden, they all in- stantly started away. These monkeys behaved very dif- ferently when a dead fish, a mouse, and some other new objects, were placed in their cages ; for, though at first frightened, they soon approached, handled and examined them. I then placed a live snake in a paper bag, with the mouth loosely closed, in one of the larger compart- ments. One of the monkeys immediately approached, cautiously opened the bag a little, peeped in, and in- stantly dashed away. Then I witnessed what Brehm has described, for monkey after monkey, with head raised high and turned on one side, could not resist taking mo- mentary peeps into the upright bag, at the dreadful object lying quiet at the bottom. It would almost appear as if monkeys had some notion of zoological affinities, for those kept by Brehm exhibited a strange, though mistaken, in- stinctive dread of innocent lizards and frogs. An orang, also, has been known to be much alarmed at the first sight of a turtle.9 The principle of Imitation is strong in man, and espe- cially in man in a barbarous state. Desor 10 has remarked that no animal voluntarily imitates an action performed by man, until in the ascending scale we come to monkeys, which are well known to be ridiculous mockers. Animals, however, sometimes imitate each others' actions : thus two species of wolves, which had been reared by dogs, learned to bark, as does sometimes the jackal,11 but whether this can be called voluntary imitation is another question. 9 W. C. L. Martin, ' Nat. Hist, of Mammalia,' 1841, p. 405. 10 Quoted by Yogt, 'Memoire surles Microccphales,' 1867, p. 168. 11 ' The Variation of Animals and Plants under Domestication,' vol. L p. 27. Chap. II.] MENTAL POWERS. 43 From one account which I have read, there is reason to believe that puppies nursed by cats sometimes learn to lick their feet and thus to clean their faces : it is at least certain, as I hear from a perfectly trustworthy friend, that some doo-s behave in this manner. Birds imitate the songs of their parents, and sometimes those of other birds ; and parrots are notorious imitators of any sound which they often hear. Hardly any faculty is more important for the intellec- tual progress of man than the power of Attention. Ani- mals clearly manifest this power, as when a cat watches by a hole and prepares to spring on its prey. Wild animals sometimes become so absorbed when thus en^ao-ed, that they may be easily approached. Mr. Bartlett has given me a curious proof how variable this faculty is in mon- keys. A man who trains monkeys to act used to purchase common kinds from the Zoological Society at the price of five pounds for each ; but he offered to give double the price, if he might keep three or four of them for a few days, in order to select one. When asked how he could possibly so soon learn whether a particular monkey would turn out a good actor, he answered that it all depended on their power of attention. If when he was talking and explaining any thing to a monkey, its attention was easily distracted, as by a fly on the wall or other trifling object, the case was hopeless. If he tried by punishment to make an inattentive monkey act, it turned sulky. On the other hand, a monkey which carefully attended to him could always be trained. It is almost superfluous to state that animals have ex- cellent Memories for persons and places. A baboon at the Cape of Good Hoj)e, as I have been informed by Sir An- drew Smith, recognized him with joy after an absence of nine months. I had a dog who was savage and averse to all strangers, and I purposely tried his memory after an 44 THE DESCENT OF MAN. [Part. I. absence of five years and two days. I went near the sta- ble where he lived, and shouted to him in my old manner; he showed no joy, but instantly followed me out walking and obeyed me, exactly as if I had parted with him only half an hour before. A train of old associations, dormant during five years, had thus been instantaneously awakened in his mind. Even ants, as P. Huber 12 has clearly shown, recognized their fellow-ants belonging to the same com- munity after a separation of four months. Animals can certainly by some means judge of the intervals of time between recurrent events. The Imagination is one of the highest prerogatives of man. By this faculty he unites, independently of the will, former images and ideas, and thus creates brilliant and novel results. A poet, as Jean Paul Richter remarks,13 "who must reflect whether he shall make a character say yes or no — to the devil with him ; he is only a stupid corpse." Dreaming gives us the best notion of this power ; as Jean Paul again says, " The dream is an invol- untary art of poetry." The value of the products of our imagination depends of course on the number, accuracy, and clearness of our impressions ; on our judgment and taste in selecting or rejecting the involuntary combina- tions, and to a certain extent on our power of voluntarily combining them. As dogs, cats, horses, and probably all the higher animals, even birds, as is stated on good au- thority,14 have vivid dreams, and this is shown by their movements and voice, we must admit that they possess some power of imagination. Of all the faculties of the human mincl, it will, I pre- sume, be admitted that Reason stands at the summit. 12 'Les Mccurs des Fourmis,' 1810, p. 150. 13 Quoted in Dr. Maudsley's 'Physiology and Pathology of Mind,' 1868, pp. 19, 220. 14 Dr. Jerdon,' Birds of India,' vol. i. 1862 p. xxi. Chap. II.] MENTAL POWERS. 45 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 unlearned instincts.15 In future chapters we shall see that some animals extremely low in the scale apparently display a certain amount of reason. No doubt it is often difficult to distinguish between the power of reason and that of instinct. Thus Dr. Hayes, in his work on 'The Open Polar Sea,' repeatedly remarks that his dogs, instead of continuing to draw the sledges in a com- pact body, diverged and separated when they came to thin ice, so that their weight might be more evenly dis- tributed. This was often the first warning and notice which the travellers received that the ice was becoming thin and dangerous. Now, did the dogs act thus from the experience of each individual, or from the example of the older and wiser dogs, or from an inherited habit, that is, from an instinct ? This instinct might possibly have arisen since the time, long ago, when dogs were first em- ployed by the natives in drawing their sledges ; or the Arctic wolves, the parent-stock of the Esquimaux dog, may have acquired this instinct, impelling them not to attack their prey in a close pack when on thin ice. Ques- tions of this kind are most difficult to answer. So many facts have been recorded in various works showing that animals possess some degree of reason, that I will here give only two or three instances, authenticated by Rengger, and relating to American monkeys, which stand low in their order. He states that when he first gave eggs to his monkeys, they smashed them and thus 15 Mr. L. H. Morgan's work on 'The American Beaver,' 1868, offers a good illustration of this remark. I cannot, however, avoid thinking that he goes too far in underrating the power of Instinct. IQ THE DESCENT OP MAN. [Part I. lost much of their contents ; afterward they gently hit one end against some hard body, and picked off the bits of shell with their fingers. After cutting themselves only once with any sharp tool, they would not touch it again, or would handle it with the greatest care. Lumps of sugar were often given them wrapped up in paper; and Rengger sometimes put a live wasp in the paper, so that in hastily unfolding it they got stung ; after this had once happened, they always first held the packet to their ears to detect any movement within. Any one who is not con- vinced by such facts as these, and by what he may observe with his own dogs, that animals can reason, would not be convinced by any thing that I could add. Nevertheless I will give one case with respect to dogs, as it rests on two distinct observers, and can hardly depend on the modification of any instinct. Mr. Colquhoun 16 winged two wild-ducks, which fell on the opposite side of a stream ; his retriever tried to bring over both at once, but could not succeed ; she then, though never before known to ruffle a feather, deliberately killed one, brought over the other, and returned for the dead bird. Colonel Hutchinson relates that two partridges were shot at once, one being killed, the other wounded ; the latter ran away, and was caught by the retriever, who on her return came across the dead bird ; " she stopped, evidently greatly puzzled, and after one or two trials, finding she could not take it up without permitting the escape of the winged bird, she considered a moment, then deliberately murdered it by giving it a severe crunch, and afterward brought away both together. This was the only known instance of her ever having wilfully injured any game." Here we have reason, though not quite per- fect, for the retriever might have brought the wounded 16 'The Moor and the Loch,' p. 45. Colonel Hutchinson on 'Dog Breaking,' 1850, p. 46. Chap. II.] MENTAL POWERS. 47 bird first and then returned for the dead one, as in the case of the two wild-ducks. The muleteers in South America say, " I will not give you the mule whose step is easiest, but la mas rational, — the one that reasons best ; " and Humboldt 17 adds, "this popular expression, dictated by long experience, combats the system of animated machines, better perhaps than all the arguments of speculative philosophy." It has, I think, now been shown that man and the higher animals, especially the Primates, have some few instincts in common. All have the same senses, intuitions, and sensations — similar passions, affections, and emotions, even the more complex ones ; they feel wonder and curi- osity ; they possess the same faculties of imitation, atten- tion, memory, imagination, and reason, though in very different degrees. Nevertheless many authors have in- sisted that man is separated through his mental faculties by an impassable barrier from all the lower animals. I formerly made a collection of above a score of such apho- risms, but they are not worth giving, as their wide differ- ence and number prove the difficulty, if not the impossi- bility, of the attempt. It has been asserted that man alone is capable of progressive improvement ; that he alone makes use of tools or fire, domesticates other ani- mals, possesses property, or employs language ; that no other animal is self-conscious, comprehends itself, has the power of abstraction, or possesses general ideas ; that man alone has a sense of beauty, is liable to caprice, has tlic feeling of gratitude, mystery, etc. ; believes in God, oi- ls endowed with a conscience. I will hazard a few remarks on the more important and interesting of these points Archbishop Sumner formerly maintained18 that man 17 'Personal Narrative,' Eng. translat., vol. iii. p. 106. 18 Quoted by Sir C. Lyell, ' Antiquity of Man,' p. 497. 48 THE DESCENT OF MAN. [Part I. alone is capable of progressive improvement. With ani- mals, looking first to the individual, every one who has had any experience in setting traps knows that young animals can be caught much more easily than old ones ; and they can be much more easily approached by an enemy. Even with respect to old animals, it is impossible to catch many in the same place and in the same kind of trap, or to destroy them by the same kind of poison ; yet it is improbable that all should have partaken of the poi- son, and impossible that all should have been caught in the trap. They must learn caution by seeing their breth- ren caught or poisoned. In North America, where the fur-bearing animals have long been pursued, they exhibit, according to the unanimous testimony of all observers, an almost incredible amount of sagacity, caution, and cun- ning; but 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 indi- vidual experience. A good observer, Leroy,20 states that in districts where foxes are much hunted, the young when they first leave their burrows are incontestable much more wary than the old ones in districts where they are not much disturbed. Our domestic doses are descended from wolves and jackals,21 and though they may not have gained in cun- 19 ' Journal of Researches during the Voyage of the " Beagle," ' 1845, o. 398. ' Origin of Species,' 5th edit. p. 260. 50 'Lettres Phil, sur Tlutelligence des Animaux,' nouvelle 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.' Chap. II.] MENTAL. TOWERS. 49 ning, and may have lost in wariness and suspicion, yet they have progressed in certain moral qualities, such as in affection, trustworthiness, temper, and probably in gen- eral intelligence. The common rat has conquered and beaten several other species throughout Europe, in parts of North America, New Zealand, and recently in For- mosa, as well as on the main-land of China. Mr. S win- hoe,28 who describes these latter cases, attributes the vic- tory of the common rat over the large Mus coninga to its superior cunning ; and this latter quality may be at- tributed to the habitual exercise of all its faculties in avoiding extirpation by man, as well as to nearly all the less cunning or weak-minded rats having been successively destroyed by him. To maintain, independently of any direct evidence, that no animal during the course of ages has progressed in intellect or other mental faculties, is to beg the question of the evolution of species. Hereafter we shall see that, according to Lartet, existing mammals belonging;; to several orders have larger brains than their ancient tertiary prototypes. It has often been said that no animal uses any tool ; but the chimpanzee in a state of nature cracks a native fruit, somewhat like a walnut, with a stone.23 Kengger 24 easily taught an American monkey thus to break open hard palm-nuts, and afterward of its own accord it used stones to open other kinds of nuts, as well as boxes. It thus also removed the soft rind of fruit that had a disa- greeable flavor. Another monkey was taught to open the lid of a large box with a stick, and afterward it used the stick as a lever to move heavy bodies ; and I have myself gcen a young orang put a stick^ into a crevice, slip his 22 'Proc. Zoolog. Soc' 1864, p. 186. 23 Savage and Wyman in 'Boston Journal of Nat. Hist.' vol. iv. 1843 -'44, p. 383. 84 ' Saugethiere von Paraguay,' 1830, s. 51-56. 50 THE DESCENT OF MAN. [Part I. hand to the other end, and use it in the proper manner as a lever. In the cases just mentioned stones and sticks were employed as implements ; but they are likewise used as wea]3ons. Brehm25 states, on the authority of the well- known traveller Schinij^er, that in Abyssinia when the baboons belonging to one species ( G. gelada) descend in troops from the mountains to plunder the fields, they sometimes encounter troops of another species (0. hama- dryas), and then a fight ensues. The Geladas roll down great stones, which the Hamadryas try to avoid, and then both species, making a great uproar, rush furiously against each other. Brehm, when accompanying the Duke of Coburg-Gotha, aided in an attack with fire-arms on a troop of baboons in the pass of Mensa in Abyssinia. The baboons in return rolled so many stones down the mountain, some as large as a man's head, that the at- tackers had to beat a hasty retreat ; and the pass was actually for a time closed against the caravan. It de- serves notice that these baboons thus acted in concert. Mr. Wallace26 on three occasions saw female orangs, ac- companied by their young, " breaking off branches and the great spiny fruit of the Durian-tree, with every ap- ]>earance 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 prop- erty; but this idea is common to every dog with a bone, and to most or all birds with their nests. The Duke of Argyll " remarks, that the fashioning of 25 ' Thierleben,' B. i. s. 79, 82. 26 'The Malay Archipelago,' vol. i. 1869, p. 87. 21 ' Primeval Man,' 1869, pp. 145, 147. Chap. II.] MENTAL POWERS. 51 an implement for a special purpose is absolutely peculiar to man ; and he 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 prime- val 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 flints, and not a very wide step to rudely fashion them. This latter advance, however, may have taken long ages, if we may judge by the immense interval of time which elapsed before the men of the neolithic period took to grinding and polishing their stone tools. In breaking the flints, as Sir J. Lub- bock likewise remarks, sparks would have been emitted, and in grinding them heat would have been evolved: "thus the two usual methods of obtaining fire may have originated." The nature of fire would have been known in the many volcanic regions where lava occasionally flows through forests. The anthropomorphous apes, guided probably by instinct, build for themselves tempo- rary platforms ; but as many instincts are largely con- trolled by reason, the simpler ones, such as this of build- ing a platform, might readily pass into a voluntary and conscious act. The orang is known to cover itself at night with the leaves of the Pandanus ; and Brehm states that one of his baboons used to protect itself from the heat of the sun by throwing a straw mat over its head. In these latter habits, we probably see the first steps toward some of the simpler arts ; namely, rude architec- ture and dress, as they arose among the early progeni- tors of man. : Language. — This faculty has justly been considered as one of the chief distinctions between man and the lower 29 'Prehistoric Times,' 1865, p. 473, etc. 52 THE DESCENT OF MAN. [Part I. 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 his mind, and can understand, more or less, what is so ex- pressed by another." 29 In Paraguay the Cebus azarce when excited utters at least six distinct sounds, which ex- cite in other monkeys similar emotions.30 The movements of the features and gestures of monkeys are understood by us, and they partly understand ours, as Rengger and others declare. It is a more remarkable fact that the dog, O 7 since being domesticated, has learned to bark 31 in at least four or five distinct tones. Although barking is a new art, no doubt the wild species, the parents of the dog, ex- pressed 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, ho w ever, peculiar to man ; but he uses in common with the lower animals inarticulate cries to express his meaning, aided by gestures and the movements of the muscles of the face.32 This especially holds good with the more simple and vivid feelings, which are but little connected with our higher intelli- gence. Our cries of pain, fear, surprise, anger, together with their appropriate actions, and the murmur of a 99 Quoted in 'Anthropological Review,' 1864, p. 15S. 30 Rengger, ibid. s. 45. 31 See my 'Variation of Animals and Plants under Domestication,' vol. i. p. 27. 3i See a discussion on this subject in Mr. E. P>. Trior's very interest- ing work, 'Researches into the Early History of Mankind,' 1665, chaps, ii. to iv. Chap. II.] MENTAL POWERS. 53 mother to her beloved child, are more expressive than any words. It is not the mere power of articulation that dis- tinguishes man from other animals, for, as every one knows, parrots can talk ; but it is his large power of con- necting definite sounds with definite ideas ; and this obvious- ly depends on the development of the mental faculties. As Home 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 much more appropriate simile. It certainly is not a true in- stinct, as every language has to be learned. It differs, however, widely from all ordinary arts, for man has an instinctive tendency to speak, as we see in the babble of our young children; while no child has an instinctive tendency to brew, bake, or write. Moreover, no philolo- gist now supposes that any language has been deliberately invented; each has been slowly and unconsciously de- veloped 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 in- stinctive cries expressive of their emotions ; and all the kinds that have the power of singing exert this power in- stinctively ; but the actual song, and even the call-notes, are learned from their parents or foster-parents. These sounds, as Daines Barrington 33 has proved, " are no more innate than language is in man." The first attempt to sing " may be compared to the imperfect endeavor in a child to babble." The young males continue practising, or, as the bird-catchers say, recording, for ten or eleven months. Their first essays show hardly a rudiment of the future song ; but as they grow older we can perceive what they are aiming at ; and at last they are said " to sing 33 Hon. Daines Barrington in 'Philosoph. Transactions,' 1773, p. 262. See also Dureau de la Malle, in ' Ann. des Sc. Nat.' 3d series, Zoolog. torn. x. p. 119. 54 THE DESCENT OF MAN. [Part I. their song round." Nestlings which have learned the song of a distinct species, as with the canary-birds educated in the Tyrol, teach and transmit their new song to their off- spring. The slight natural differences of song in the same species inhabiting different districts may be appositely compared, as Barrington remarks, "to provincial dia- lects ; " and the songs of allied though distinct species may be compared with the languages of distinct races of man. I have given the foregoing details to show that an instinctive tendency to acquire an art is not a peculiarity confined to man. With respect to the origin of articulate language, after having read on the one side the highly-interesting works of Mr. Hensleigh Wedgwood, the Kev. F. Farrar, and Prof. Schleicher,34 and the celebrated lectures of Prof. Max Miiller on the other side, I cannot doubt that lan- guage owes its origin to the imitation and modification, aided by signs and gestures, of various natural sounds, the voices of other animals, and man's own instinctive cries. When we treat of sexual selection we shall see that primeval man, or rather some early progenitor of man, probably used his voice largely, as does one of the gibbon-apes at the present day, in producing true musical cadences, that is in singing ; we may conclude from a widely-spread analogy that this power would have been especially exerted during the courtship of the sexes, serv- ing to express various emotions, as love, jealousy, triumph, and serving as a challenge to their rivals. The imitation by articulate sounds of musical cries might have given 34 ' On the Origin of Language,' by II. Wedgwood, 1866. 'Chapters on Language,' by the Kev. F. W. Farrar, 1865. These works are most interesting. See also ' De la Phys. et de Parole,' par Albert Lemoine, 1885, p. 190. The work on this subject, by the late Prof. Aug. Schlei- cher, has been translated by Dr. Bikkers into English, under the title of 'Darwinism tested by the Science of Language,' 1869. Chap. II.] MENTAL POWERS. 55 rise to words expressive of various complex emotions. As bearing on the subject of imitation, the strong tendency in our nearest allies, the monkeys, in microcephalous idiots,35 and in the barbarous races of mankind, to imi- tate whatever they hear deserves notice. As monkeys certainly understand much that is said to them by man, and as in a state of nature they utter signal-cries of dan- ger to their fellows,36 it does not appear altogether incred- ible, that some unusually wise ape-like animal should have thought of imitating the growl of a beast of prey, so as to indicate to his fellow-monkeys the nature of the ex- pected danger. And this would have been a first step in the formation of a language. As the voice was used more and more, the vocal or- gans would have been strengthened and perfected through the principle of the inherited effects of use; and this would have reacted on the power of speech. But the relation between the continued use of language and the development of the brain has no doubt been far more im- portant. The mental powers in some early progenitor of man must have been more highly developed than in any existing ape, before even the most imperfect form of speech could have come into use ; but we may confidently believe that the continued use and advancement of this power would have reacted on the mind by enabling and encouraging it to carry on long trains of thought. A long and complex train of thought can no more be carried on without the aid of words, whether spoken or silent, than a long calculation without the use of figures or alge- bra. It appears, also, that even ordinary trains of thought 35 Vogt, * Memoire sur les Microcephales,' 1867, p. 169. With re- spect to savages, I have given some facts in my ' Journal of Researches,' etc., 1845, p. 206. 36 See clear evidence on this head in the two works so often quoted, by Brehm amd Rengger. 56 THE DESCENT OF MAN. [Pakt L almost require some form of language, for the dumb, deaf, and blind girl, Laura Bridgman, was observed to use her fingers while dreaming.37 Nevertheless a long succession of vivid and connected ideas may pass through the mind without the aid of any form of language, as we may in- fer from the prolonged dreams of dogs. We have, also, seen that retriever-dogs are able to reason to a certain ex- tent ; and this they manifestly do without the aid of lan- guage. The intimate connection between the brain, as it is now developed in us, and the faculty of speech, is well shown by those curious cases of brain-disease, in which speech is specially affected, as when the power to remem- ber substantives is lost, while other words can be correctly used/8 There is no more improbability in the effects of the continued use of the vocal and mental organs being inherited, than in the case of handwriting, which depends partly on the structure of the hand and partly on the dis- position of the mind; and handwriting is certainly in- herited.39 Why the organs now used for speech should have been originally perfected for this purpose, rather than any other organs, it is not difficult to see. Ants have consid- erable powers of intercommunication by means of their antennae, as shown by Huber, who devotes a whole chap- ter to their language. We misrht have used our finders as efficient instruments, for a person with practice can re- port to a deaf man every word of a speech rapidly de- livered at a public meeting ; but the loss of our hands, 37 See remarks on this head by Dr. Maudsley, * The Physiology -and Pathology of Mind,' 2d edit. 1868, p. 199. 38 Many curious cases have been recorded. See, for instance, c In- quiries concerning the Intellectual Powers,' by Dr. Abercrombie, 1838, p. 150. 39 • The Variation of Animals and Plants under Domestication,' vol ii. p. 6. Chap. II.] MENTAL POWERS. 51 while thus employed, would have beeu a serious incon- venience. As all the higher mammals possess vocal or- gans constructed on the same general plan with ours, and which are used as a means of communication, it was ob- viously probable, if the power of communication had to be improved, that these same organs wTould have been still further developed ; and this has been effected by the aid of adjoining and well-adapted parts, namely, the tongue and lips.40 The fact of the higher apes, not using their vocal organs for speech, no doubt depends on their intelligence not having been sufficiently advanced. The possession by them of organs, which with long-continued practice might have been used for speech, although not thus used, is paralleled by the case of many birds which possess organs fitted for singing, though they never sing. Thus, the nightingale and crow have vocal organs simi- larly constructed, these being used by the former for di- versified song, and by the latter merely for croaking.41 The formation of different languages and of distinct species, and the proofs that both have been developed through a gradual process, are curiously the same.42 But we can trace the origin of many words further back than in the case of species, for we can perceive that they have arisen from the imitation of various sounds, as in allitera- tive poetry. We find in distinct languages striking ho- 40 See some good remarks to this effect by Dr. Maudsley, ' The Physiology and Pathology of Mind,' 1868, p. 199. 41 Macgillivray, ' Hist, of British Birds,' vol. ii. 1839, p. 29. An ex. eellent observer, Mr. Blackwall, remarks that the magpie learns to pro- nounce single words, and even short sentences, more readily than almosl any other British bird ; yet, as he adds, after long and closely investigat ing its habits, he has never known it, in a state of nature, display anj unusual capacity for imitation. 'Researches in Zoology,' 1834, p. 158. 42 See the very interesting parallelism between the development of species and languages, given by Sir C. Lyell, in ' The Geolog. Evidences of the Antiquity of Man,' 1803, chap, xxiii. 58 THE DESCENT OF MAN. [Part I. mologies clue to community of descent, and analogies due to a similar process of formation. The manner in which certain letters or sounds change when others change is very like correlated growth. We have in both cases the reduplication of parts, the effects of long-continued use, and so forth. The frequent presence of rudiments, both in languages and in species, is still more remarkable. The letter m in the word am, means J/ so that in the expres- sion Jam, a superfluous and useless rudiment has been re- tained. In the spelling also of words, letters often remain as the rudiments of ancient forms of pronunciation. Lan- guages, like organic beings, can be classed in groups under groups ; and they can be classed either naturally, accord- ing to descent, or artificially by other characters. Domi- nant languages and dialects spread widely and lead to the gradual extinction of other tongues. A language, like a species, when once extinct, never, as Sir C. Lyell remarks, reappears. The same language never has two birthplaces. Distinct languages may be crossed or blended together.43 "We see variability in every tongue, and new words are continually cropping up ; but as there is a limit to the powers of the memory, single words, like whole languages, gradually become' extinct. As Max Miiller 44 has well re- marked : " A struggle for life is constantly going on among the words and grammatical forms in each language. The better, the shorter, the easier forms are constantly gaining the upper hand, and they owe their success to their own inherent virtue." To these more important causes of the survival of certain words, mere novelty may, I think, be added : for there is in the mind of man a stromr love for slight changes in all things. The survival or preservation 43 See remarks to this effect by the Rev. F. W. Farrar, in an interest- rag article, entitled " Philology and Darwinism," in ' Nature,' March 24, 1870, p. 528. 44 'Nature,' Jan. 6, 1870, p. 257. Cuap. II.] MENTAL TOWERS. 59 of certain favored words in the struggle for existence is natural selection. The perfectly regular and wonderfully complex con- struction of the languages of many barbarous nations has often been advanced as a proof, either of the divine origin of these languages, or of the high art and former civiliza- tion of their founders. Thus F. von Schlegel writes : " In those languages which appear to be at the lowest grade of intellectual culture, we frequently observe a very high and elaborate degree of art in their grammatical structure. This is especially the case with the Basque and the Lap- ponian, and many of the American languages." 45 But it is assuredly an error to speak of any language as an art in the sense of its having been elaborately and methodi- cally formed. Philologists now admit that conjugations, declensions, etc., originally existed as distinct words, since joined together ; and as such words express the most ob- vious relations between objects and persons, it is not sur- prising that they should have been used by the men of most races during the earliest ages. With respect to per- fection, the following illustration will best show how easily we may err : a Crinoid sometimes consists of no less than 150,000 pieces of shell,48 all arranged with perfect symme- try in radiating lines ; but a naturalist does not consider an animal of this kind as more perfect than a bilateral one with comparatively few parts, and with none of these alike, excepting on the opposite sides of the body. He justly considers the differentiation and specialization of organs as the test of perfection. So with languages, the most symmetrical and complex ought not to be ranked above irregular, abbreviated, and "bastardized languages, which have borrowed expressive words and useful forms of construction from various conquering, or conquered, or immigrant races. 45 Quoted by C. S. Wake, ' Chapters on Man,' 1868, p. 101. 46 Buckland, 'Bridgewater Treatise,' p. 411. 60 THE DESCENT OF MAN. [Part I From these few and imperfect remarks, I conclude that the extremely complex and regular construction of many barbarous languages is no proof that they owe their origin to a special act of creation.47 Nor, as we have seen, does the faculty of articulate speech in itself offer any insuper- able objection to the belief that man has been developed from some lower form. Self -consciousness, Individuality, Abstraction, General Ideas, etc. — It would be useless to attempt discussing these high faculties, which, according to several recent writers, make the sole and complete distinction between man and the brutes, for hardly two authors agree in their defini- tions. Such faculties could not have been fully developed in man until his mental powers had advanced to a high standard, and this implies the use of a perfect language. No one supposes that one of the lower animals reflects whence he comes or whither he goes — what is death, or what is life, and so forth. But can we feel sure that an old dog with an excellent memory, and some power of imagination, as shown by his dreams, never reflects on his past pleasures in the chase ? and this would be a form of self-consciousness. On the other hand, as Biichner 48 has remarked, how little can the hard-worked wife of a de- graded Australian savage, who uses hardly any abstract words, and cannot count above four, exert her self-con- sciousness, or reflect on the nature of her own existence ! That animals retain their mental individuality is un- questionable. When my voice awakened a train of old associations in the mind of the above-mentioned dog, ho must have retained his mental individuality, although 47 See some good remarks on the simplification of languages, by Sir J. Lubbock, 'Origin of Civilization,' 1870, p. 278. 48 ' Conferences sur la Theorie Darwinienne,' French translat., 186?, p. 132. Chap. II.] MENTAL POWERS. 61 every atom of his brain had probably undergone change more than once daring the interval of five years. This dog might have brought forward the argument lately ad- vanced to crush all evolutionists, and said, " I abide amid all mental moods and all material changes. . . . The teaching that atoms leave their impressions as legacies to other atoms falling into the places they have vacated is contradictory of the utterance of consciousness, and is therefore false ; but it is the teaching necessitated by evo- lutionism, consequently the hypothesis is a false one." 49 Sense of Beauty. — This sense has been declared to be peculiar to man. But when we behold male birds elabo- rately displaying their plumes and splendid colors before the females, while other birds not thus decorated make no such display, it is impossible to doubt that the females admire the beauty of their male partners. As women everywhere deck themselves with these plumes, the beauty of such ornaments cannot be disputed. The Bower-birds by tastefully ornamenting their playing-passages with gayly-colored objects, as do certain humming-birds their nests, offer additional evidence that they possess a sense of beauty. So with the song of birds, the sweet strains poured forth by the males during the season of love are certainly admired by the females, of which fact evidence will hereafter be given. If female birds had been in- capable of appreciating the beautiful colors, the orna- ments, and voices of their male partners, all the labor and anxiety exhibited by them in displaying their charms be- fore the females would have been thrown away ; and this it is impossible to admit. Why certain bright colors and sextain sounds should excite pleasure, when in harmony, cannot, I presume, be explained any more than why cer- tain flavors and scents are agreeable; but assuredly the 49 The Rev. Dr. J. M'Cann, ' Anti-Darwinism,' 18G9, p. 13. 62 THE DESCENT OF MAN. [Part I. same colors and the same sounds are admired by us and by many of the lower animals. The taste for the beautiful, at least as far as female beauty is concerned, is not of a special nature in the hu- man mind ; for it differs widely in the different races of man, as wull hereafter be shown, and is not quite the same even in the different nations of the same race. Judging from the hideous ornaments and the equally hideous music admired by most savages, it might be urged that their aesthetic faculty was not so highly developed as in certain animals, for instance, in birds. Obviously no animal would be capable of admiring such scenes as the heavens at night, a beautiful landscape, or refined music ; but such high tastes, depending as they do on culture and complex associations, are not enjoyed by barbarians or by unedu cated persons. Many of the faculties, which have been of inestimable service to man for his progressive advancement, such as the powers of the imagination, wonder, curiosity, an un- defined sense of beauty, a tendency to imitation, and the love of excitement or novelty, could not fail to have led to the most capricious changes of customs and fashions. I have alluded to this point, because a recent writer B0 has oddly fixed on Caprice " as one of the most remarkable and typical differences between savages and brutes." But not only can we perceive how it is that man is capricious, but the lower animals are, as we shall hereafter see, capri- cious in their affections, aversions, and sense of beauty. There is also good reason to suspect that they love nov- elty, for its own sake. Belief in God — Religion. — There is no evidence that man was aboriginally endowed with the ennobling belief in the existence of an Omnipotent God. On the contrary, 60 ' The Spectator,' Dec. 4, 1860, p. 1430. Chap. II.] MENTAL TOWERS. 6 there is amp±e evidence, derived not fro*n hasty travellers, but from men who have long resided with savages, that numerous races have existed and still exist, who have no idea of one or more gods, and who have no words in their languages to express such an idea.51 The question is of course wholly distinct from that higher one, whether there exists a Creator and Ruler of the universe ; and this has been answered in the affirmative by the highest intellects that have ever lived. If, however, we include under the term " religion " the belief in unseen or spiritual agencies, the case is wholly different ; for this belief seems to be almost universal with the less civilized races. Nor is it difficult to comprehend how it arose. As soon as the important faculties of the imagination, wonder, and curiosity, together with some power of reasoning, had become partially developed, man would naturally have craved to understand what was passing around him, and have vaguely speculated on his own existence. As Mr. M'Lennan 52 has remarked, " Some explanation of the phenomena of life, a man must feign for himself; and to judge from the universality of it, the simplest hypothesis, and the first to occur to men, seems to have been that natural phenomena are ascribable to the presence in animals, plants, and things, and in the forces of Nature, of such spirits prompting to action as men are conscious they themselves possess." It is prob- able, as Mr. Tylor has clearly shown, that dreams may have first given rise to the notion of spirits ; for savages do not readily distinguish between subjective and objec- 61 See an excellent article on this subject by the Rev. E. W. Farrar, in the 'Anthropological Review,' Aug. 1864, p. cexvii. For further facts eee Sir J. Lubbock, 'Prehistoric Times,' 2d edit. 1869, p. 564 ; and es- pecially the chapters on Religion in his 'Origin of Civilization,' 18*70. 62 The Worship of Animals and Plants, in the ' Fortnightly Review,' Oct. I, 1869, p. 422 64 THE DESCENT OF MAN. [Part I. tive impressions. When a savage dreams, the figures which appear before him are believed to have come from a distance and to stand over him ; or " the soul of the dreamer goes out on its travels, and comes home with a remembrance of what it has seen." B3 But until the above- named faculties of imagination, curiosity, reason, etc., had been fairly well developed in the mind of man, his dreams would not have led him to believe in spirits, any more than in the case of a dog. The tendency in savages to imagine that natural ob- jects and agencies are animated by spiritual or living es- sences, is perhaps illustrated by a little fact which I once noticed : My dog, a full-grown and very sensible animal, was lying on the lawn during a hot and still day ; 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 it was, every time that the parasol slightly moved, the dog growled fiercely and barked. He must, I think, have reasoned to himself in a rapid and unconscious manner, that move- 53 Tylor, 'Early History of Mankind,' 1865, p. 6. See also the three striking chapters on the Development of Religion, in Lubbock's ' Origin of Civilization,' 1870. In a like manner Mr. Herbert Spencer, in his in- genious essay in the 'Fortnightly Review' (May 1, 1870, p. 535), ac- counts for the earliest forms of religious belief throughout the world, by man being led through dreams, shadows, and other causes, to look at himself as a double essence, corporeal and spiritual. As the spiritual being is supposed to exist after death and to be powerful, it is propi- tiated by various gifts and ceremonies, and its aid invoEed. He then further shows that names or nicknames given from some animal or other object to the early progenitors or founders of a tribe, are supposed after a long interval to represent the real progenitor of the tribe ; and such animal or object is then naturally believed still to exist as a spirit, is held sacred, and worshipped as a god. Nevertheless I cannot but suspect that there is a still earlier and ruder stage, when any thing which manifests power or movement is thought to be endowed with some form of life, and with mental faculties analogous to our own. Ciiap. II.] MENTAL TOWERS 05 ment without any apparent cause indicated the presence of some strange living agent, and no stranger had a right to be on his territory. The belief in spiritual agencies would easily pass into the belief in the existence of one or more gods. For savages would naturally attribute to spirits the same pas- sions, the same love of vengeance or simplest form of jus- tice, and the same affections which they themselves expe- rienced. The Fuegians appear to be in this respect in an intermediate condition, for when the surgeon on board the " Beagle " shot some young ducklings as specimens, York Minster declared in the most solemn manner, " Oh ! Mr. Bynoe, much rain, much snow, blow much ; " and this was evidently a retributive punishment for wasting human food. So again he related how, when his brother killed a " wild man," storms long raged, much rain and snow fell. Yet we could never discover that the Fuegians believed in what we should call a God, or practised any religious rites; and Jemmy Button, with justifiable pride, stoutly maintained that there was no devil in his land. This lat- ter assertion is the more remarkable, as with savages the belief in bad spirits is far more common than the belief in good spirits. The feeling of religious devotion is a highly complex 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 an emotion until advanced in his intellectual and moral fac- ulties to at least a moderately high level. Nevertheless we see some distant approach to this state of mind, in the deep love of a dog for his master, associated with com- plete submission, some fear, and perhaps other feelings. 54 See an able article on the Psychical Elements of Religion, by Mr. L. Owen Pike, in ' Anthropolog. Review,' April, 1870, p. briii 4 06 THE DESCENT OF MAN. [Part I. The behavior of a dog when returning to his master after an absence, and, as I may add, of a monkey to his beloved keeper, is widely different from that toward their fellows. In the latter case the transports of joy appear to be some- what less, and the sense of equality is shown in every ac- tion. Prof. Braubach 65 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 fetishism, polytheism, and ultimately in monotheism, would infalli- bly lead him, as long as his reasoning powers remained poorly developed, to various strange superstitions and cus- toms. 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 ; witch- craft, etc. — yet it is well occasionally to reflect on these superstitions, for they show us what an infinite debt of gratitude we owe to the improvement of our reason, to science, and our accumulated knowledge.66 As Sir J. Lubbock has well observed, " it is not too much to say that the horrible dread of unknown evil hangs like a thick cloud over savage life, and embitters every pleasure." These miserable and indirect consequences of our highest faculties may be compared with the incidental and occa- sional mistakes of the instincts of the lower animals. 55 'Religion, Moral, etc., der Darwin'schen Art-Lehre,' 1869, s. 53. 56 ' Prehistoric Times,' 2d edit. p. 571. In this work (at p. 553) there will be found an excellent account of the many strange and capri. cious customs of savages. Chap III., MORAL SENSE CI CHAPTER III. COMPAKISON OF THE MENTAL TOWERS 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 re- garded by Savages. — Tho Self-regarding Virtues acquired at a Later Stage of Development. — The Importance of the Judgment of the Members of the same Community on Conduct. — Transmission of Moral Tendencies. — Summary. I fully subscribe to the judgment of those writers * who maintain that, of all the differences between man and the lower animals, the moral sense or conscience is by far the most important. This sense, as Mackintosh 2 remarks, " has a rightful supremacy over every other principle of human action ; " it is summed up in that short but impe- rious word ought, so full of high significance. It is the most noble of all the attributes of man, leading him with- out a moment's hesitation to risk his life for that of a fel- low-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 ! Won- drous thought, that workest neither by fond insinuation, 1 See, for instance, on this subject, Quatrefages, 'Unite de l'Espece Himaine,' 1861, p. 21, etc. * 'Dissertation on Ethical Philosophy,' 183Y, p. 231, etc. 08 TIIE DESCENT OF MAK [Part I flattery, nor by any threat, but merely by holding up thy naked law in the soul, and so extorting for thyself always reverence, if not always obedience ; before whom all ap- petites are dumb, however secretly they rebel; whence thy original ? " 3 This great question has been discussed by many writ- ers 4 of consummate ability ; and my sole excuse for touch- ing on it is the impossibility of here passing it over, and because, as far as I know, no one has approached it exclu- sively from the side of natural history. The investigation possesses, also, some independent interest, as an attempt to see how far the study of the lower animals can throw light on one of 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 would inevitably ac- quire a moral sense or conscience, as soon as its intellect- 8 'Metaphysics of Ethics,' translated by J. "VV. Semple, Edinburgh, 1836, p. 136. 4 Mr. Bain gives a list (' Mental and Moral Science,' 1868, pp. 543-Y25) of twenty-six British authors who have written on this subject, and whose names are familiar to every reader ; to these, Mr. Bain's own name, and those of Mr. -Lecky, Mr. Shadworth Hodgson, and Sir J. Lubbock, as well as of others, may be added. 5 Sir B. Brodie, after observing that man is a social animal (' Psycho- logical Inquiries,' 1854, p. 192), asks the pregnant question, "Ought not this to settle the disputed question as to the existence of a moral sense ? " Similar ideas have probably occurred to many persons, as they did long ago to Marcus Aurelius. Mr. J. S. Mill speaks, in his celebrated work, ' Utilitarianism' (1864, p. 46), of the social feelings as a "powerful natu- ral sentiment," and as " the natural basis of sentiment for utilitarian mo- rality;" 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 with hesitation that I venture to differ from so pro- found a thinker, but it can hardly be disputed that the social feelings are instinctive or innate in the lower animals ; and why should they not be so in man? Mr. Bain (see, for instance, ' The Emotions and the Will," 1805, Chap. III. MORAL SENSE. 69 ual powers had become as well developed, or nearly as well developed, as in man. For, firstly, the social in- stincts 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 ser- vices may be of a definite and evidently instinctive nature; or there may be only a wish and readiness, as with most of the higher social animals, to aid their fellows in certain general ways. But these feelings and services are by no means extended to all the individuals of the same species, only to those of the same association. Secondly, as soon as the mental faculties had become highly developed, images of all past actions and motives would be inces- santly 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 impression. It is clear that many instinctive desires, such as that of hun- ger, are in their nature of short duration ; and after being satisfied are not readily or vividly recalled. Thirdly, after the power of language had been acquired and the wishes of the members of the same community could be distinctly expressed, the common opinion how each mem- ber ought to act for the public good, would naturally be- come to a large extent the guide to action. But the so- cial instincts would still give the impulse to act for the good of the community, this impulse being strengthened, directed, and sometimes even deflected, by public opinion, the power of which rests, as we shall presently see, on in- p. 481) and others believe that the moral sense is acquired by each indi- vidual during his lifetime. On the general theory of evolution this is at least extremely improbable. 70 THE DESCENT OF MAN. [Part I. stinctive sympathy. Lastly, habit in the individual would ultimately play a very important part in guiding the con- duct of each member; for the social instincts and im- pulses, like all other instincts, would be greatly strength- ened by habit, as would obedience to the wishes and judg- ment of the community. These several subordinate prop- ositions must now be discussed ; and some of them at con- siderable length. It may be well first to premise that I do not wish to maintain that any strictly social animal, if its intellectual faculties were to become as active and as highly devel- oped as in man, would acquire exactly the same moral sense as ours. In the same manner as various animals have some sense of beauty, though they admire widely different objects, so they might have a sense of right and wrong, though led by it to follow widely different lines of conduct. If, for instance, to take an extreme case, men were reared under precisely the same conditions as hive- bees, there can hardly be a doubt that our unmarried fe males would, like the worker-bees, think it a sacred duty to kill their brothers, and mothers would strive to kill their fertile daughters ; and no one would think of interfering. Nevertheless the bee, or any other social animal, would in our supposed case gain, as it appears to me, some feeling of right and wrong, or a conscience. For each individual would have an inward sense of possessing certain stronger or more enduring instincts, and others less strong or en- during ; so that there would often be a struggle which im- pulse should be followed ; and satisfaction or dissatisfac- tion would be felt, as past impressions were compared daring their incessant passage through the mind. In this case an inward monitor would tell the animal that it would have been better to have followed the one im- pulse rather than the other. The one course ought to have been followed : the one would have been right Ciiap. III.] MORAL SENSE 71 and the other wrong ; but to these terms I shall have to recur. Sociability. — Animals of many kinds are social ; we find even distinct species living together, as with some American monkeys, and with the united nocks of rooks, jackdaws, and starlings. Man shows the same feeling in his strong love for the dog, which the dog returns with interest. Every one must have noticed how miserable horses, dogs, sheep, etc., are when separated from their companions ; and what affection at least the two former kinds show on their reunion. It is curious to speculate on the feelings of a dog, who will rest peacefully for hours in a room with his master or any of the family, without the least notice being taken of him ; but, if left for a short time by himself, barks or howls dismally. We will con- fine our attention to the higher social animals, excluding insects, although these aid each other in many important ways. The most common service which the higher ani- mals perform for each other, is the warning each other of danger by means of the united senses of all. Every sportsman knows, as Dr. Jaeger remarks,6 how difficult it is to approach animals in a herd or troop. Wild horses and cattle do not, I believe, make any danger-signal ; but the attitude of any one who 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 said 7 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 So- 6 ' Die Darwin'sche Theorie,' s. 101. ' Mr. R. Browne in 'Proc. Zoolog. Soc.' 18G8, p. 409. 8 Brehm, ■ Thierleben,' B. i. 1864, s. 52, 19. For the case of the mon- keys extracting thorns from each other, see s. 54. With respect to the 12 THE DESCENT OF MAN. [Part I. cial animals perform many little services for each other : horses nibble, and cows lick each other, on any spot which itches : monkeys search for each other's external para- sites ; and Brehm states that, after a troop of the Cerco- pithecus 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 fish in concert. The Hamadryas baboons turn over stones to find insects, etc. ; and when they come to a large one, as many as can stand round, turn it over to- gether and share the booty. Social animals mutually de- fend each other. The males of some ruminants come to the front when there is danger and defend the herd witli their horns. I shall also in a future chapter give cases of two young wild-bulls attacking an old one in concert, 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 moun- tain, and some were still in the valley : the latter were at- tacked by the dogs, but the old males immediately hurried down from the rocks, and with 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 reascended the heights, except- ing a young one, about six months old, who, loudly calling tor aid, climbed on a block of rock and was surrounded. Hamadryas turning over stones, the fact is given (s. 76) on the evidence of Alvarez, whose observations Brehm thinks quite trustworthy. For the cases of the old male baboons attacking the dogs, see s. 79 ; and, with re- spect to the eagle, s. 56. Chap. III.] MORAL SENSE. 73 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 Brehm 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 they actually sympathize with each other's pains and pleasures is more doubtful, especially with respect to the latter. Mr. Bux- ton, however, who had excellent means of observation,9 states that his macaws, which lived free in Norfolk, took " an extravagant interest" in a pair with a nest, and, when- ever the female left it, she was surrounded by a troop " screaming horrible acclamations in her honor." 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 wound- ed animal from the herd, or gore or worry it to death. This is almost the blackest fact in natural history, unless indeed the explanation which has been suggested is true, that their instinct or reason leads them to expel an in- jured companion, lest beasts of prey, including man, should be tempted to follow the troop. In this case their 9 'Annals and Mag. of Nat. Hist.' November, 1868, p. 382. U THE DESCENT OF MAN. [Part I. conduct is not much worse than that of the North Amer- ican 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 sympathize with each other's distress or danger. This is the case even with birds ; Captain Stansbury " found, on a salt lake in Utah, an old and completely blind pelican, which was very fat, and must have been long and well fed by his compan- ions. Mr. Blytb, 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 ; but such cases are much too rare for the de- velopment of any special instinct.12 I have myself seen a dog, who never passed a great friend of his, a cat which lay sick in a basket, without giving her a few licks with his tongue, the surest sign of kind feeling in a dog. It must be called sympathy that leads a courageous dog to fly at any one who strikes his master, as he cer- tainly will. I saw a person pretending to beat a lady who had a very timid little dog on her lap, and the trial had never before been made. The little creature instantly jumped away, but, after the pretended beating was over, it was really pathetic to see how perseveringly he tried to lick his mistress's face and comfort her. Brehm 13 states that when a baboon in confinement was pursued to be 10 Sir J. Lubbock, 'Prehistoric Times,' 2d edit. p. 446. 11 As quoted by Mr. L. H. Morgan, ' The American Beaver,' 18G8, p. 272. Captain Stansbury also gives an interesting account of the manner in which a very young pelican, carried away by a strong stream, was 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,' 1868, p. 245. 13 ' Thierleben,' B. i. s. 85. Chap. III.] MORAL SENSE. 75 punished, the others tried to protect him. It must have been sympathy in the cases above given which led the baboons and Cercopitheci 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 while 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 qual- ities which in us would be called moral ; and I agree with Agassiz14 that dogs possess something very like a con- science. They certainly possess some power of self-com- mand, and this does not appear to be wholly the result of fear. As Braubach16 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 obedi- ence. All animals living m a body which defend each other or attack their enemies 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 ba- boons in Abyssinia 16 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 14 'De l'Espece et de la Class.' 18G9, p. 97. 15 'Der Darwin'schen Art-Lehre,' 1869, s. 54. 16 Brehm, ' Thierlcbeu,' B. i. s. 76. jq THE DESCENT OF MAN". [Part I. that there is no danger, all show their joy by much clamor. With respect to the impulse which leads certain ani- mals to associate together, and to aid each other iu 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 actions ; or by the same sense of dissatisfaction, as in other cases of pre- vented 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 flock of sheep, but not in worrying them ; a young fox- hound delights in hunting a fox, while some other kinds of dogs, as I have witnessed, utterly disregard foxes. What a strong feeling of inward satisfaction must impel a bird, so full of activity, to brood day after day over her eggs ! Migratory birds are miserable if prevented from migrating, and perhaps they enjoy starting on their long flight. Some few instincts are determined solely by pain- ful feelings, as by fear, which leads to self-preservation, or is specially directed against certain enemies. No one, I pre- sume, can analyze the sensations of pleasure or pain. In many cases, however, it is probable that instincts are persist- ently followed from the 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 by experiencing some pleasure or pain may be erroneous. Although a habit may be blindly and implicitly followed, independently of any pleasure or pain felt at the mo- ment, yet if it be forcibly and abruptly checked, a vague Chap. III.] MORAL SENSE. 77 sense of dissatisfaction is generally experienced ; 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 conse- quence uncomfortable when separated from each other, and comfortable while together ; but it is a more probable view that these sensations were first developed, in order that those animals which would profit by living in so- ciety, should be induced to live together, in the same manner as the sense of hunger and the pleasure of eating were, no doubt, first acquired in order to induce animals to eat. The feeling of pleasure from society is probably an extension of the parental or filial affections ; and this extension may be in chief part attributed to natural selec- tion, but perhaps in part to mere habit. For with those animals which were benefited by living in close associa- tion, the individuals which took the greatest pleasure in society would best escape various dangers ; while those that cared least for their comrades and lived solitary would perish in greater numbers. With respect to the origin of the parental and filial affections, which appar- ently lie at the basis of the social affections, it is hopeless to speculate ; but we may infer that they have been to a large extent gained through natural selection. So it has almost certainly been with the unusual and opposite feel- ing of hatred between the nearest relations, as with the worker-bees which kill their brother-drones, and with the queen-bees which kill their daughter-queens ; the desire to destroy, instead of loving, their nearest relations hav- ing been here of service to the community. The all-important emotion of sympathy is distinct, from that of love. A mother may passionately love her sleeping and passive infant, but she can then hardly be said to feel sympathy for it. The love of a man for his \Tog is distinct from sympathy, and so is that of a dog 78 THE DESCENT OF MAN. [Part I. for his master. Adam Smith formerly argued, as has Mr. Bain recently, that the basis of sympathy lies in 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 of these states, which are painful even in idea." We are thus im- pelled to relieve the sufferings of another, in order that our own painful feelings may be at the same time relieved. In like manner we are led to participate in the pleasures of others.17 But I cannot see how this view explains the fact that sympathy is excited in an immeasurably stronger degree by a beloved than by an indifferent person. The mere sight of suffering, independently of love, would suffice to call up in us vivid recollections and associations. Sympathy may at first have originated in the manner above suggested ; but it seems now to have become an instinct, which is especially directed toward beloved ob- jects, in the same manner as fear with animals is especial- ly 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 sufferings of its own young, but not for any other animal. With strictly social ani- mals the feeling will be more or less extended to all the associated members, as we know to be the case. With mankind selfishness, experience, and imitation, probably add, as Mr. Bain has shown, to the power of sympathy ; 17 See the first and striking chapter in Adam Smith's ' Theory of Moral Sentiments.' Also Mr. Bain's 'Mental and Moral Science,' 1868, p. 244, and 275-282. Mr. Bain states that " sympathy is, indirectly, a source of pleasure to the sympathizer ; " and he accounts for this through reciprocity. He remarks that " the person benefited, or others in his stead, may make up, by sympathy and good offices returned, for all the sacrifice." But if, as appears to be the case, sympathy is strictly an in- stinct, its exercise would give direct pleasure, in the same manner as the exercise, as before remarked, of almost every other instiuct. Chap. III.] MORAL SENSE. 79 for we are led by the hope of receiving good in return to perform acts of sympathetic kindness to others ; and there can be 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 one of high im- portance to all those animals which aid and defend each other, it will have been increased, through natural selec- tion ; for those communities which included the greatest number of the most sympathetic members, would nourish best and rear the greatest number of offspring. In many cases it is impossible to decide whether cer- tain social instincts have been acquired through natural selection, or are the indirect result of other instincts and faculties, such as sympathy, reason, experience, and a ten- dency to imitation ; or again, whether they are simply the result of lonor-continued habit. So remarkable an instinct as the placing sentinels to warn the community of dan- ger, can hardly have been the indirect result of any other faculty ; it must therefore have been directly acquired. On the other hand, the habit followed by the males of some social animals, of defending the community and of attacking their enemies or their prey in concert, may per- haps have originated from mutual sympathy ; but courage, and in most cases strength, must have been previously ac- quired, probably through natural selection*. Of the various instincts and habits, some are much stronger than others, that is, some either give more pleas- ure in their performance and more distress in their preven- tion than others ; or, which is probably quite as important, they are more persistently followed through inheritance without exciting any special feeling of pleasure or pain. We are ourselves conscious that some habits are much more difficult to cure or change than others. Hence a strug- gle may often be observed in animals between different in- stincts, or between an instinct and some habitual disposi- SO THE DESCENT OF MAN. [Part I. tion; as when a dog rushes after a hare, is rebuked, pauses, hesitates, pursues again or returns ashamed to his master ; or as between the love of a female dog for her young puppies and for her master, for she may be seen to slink away to them, as if half ashamed of not accompany- ing: 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 wonderfully strong; a confined bird will at the proper season beat her breast against the wires of her cage, until it is bare and bloody. It causes young salmon to leap out of the fresh wTater, where they could still continue to live, 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 hesita- tion and in opposition to the instinct of self-preservation. 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 miser- ably 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 nlost strongly developed would survive in 18 This fact, the Rev. L. Jenyns states (see his edition of ' White's Nat. Hist, of Selborne,' 1853, p. 204) was first recorded by the illus- trious Jenner, in ' Phil. Transact.' 1824, and has since been confirmed by several observers, especially by Mr. Blackball. This latter careful ob- server examined, late in the autumn, during two years, thirty-six nests ; he found that twelve contained young dead birds, five contained eggs on 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 left behind. See Blackwall, 'Researches in Zoology,' lS34,pp. 108, 118. For some additional evidence, although this is not wanted, see Leroy, ' T*ttres Phil.' 1802, p. 217. Chap. III.] MORAL SENSE. 81 larger numbers. Whether this is the case with the miora- tory 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 paramount 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 suppose that man primevally lived in single families; but at the present day, though single families, or only two or three together, roam the solitudes of some savage lands, they are always, as far as I can discover, friendly with other families in- habiting the same district. Such families occasionally meet in council, and they unite for their common defence. It is no argument against savage man being a social ani- mal, that the tribes inhabiting adjacent districts are al- most always at war with each other; for the social in- stincts never extend to all the individuals of the same species. Judging from the analogy of the greater num- ber of the Quadrumana, it is probable that the early ape- like progenitors of man were likewise social ; but this is not of much importance for us. Although man, as he now exists, has few special instincts, having lost any which his early progenitors may have possessed, this is no reason why he should not have retained from an extreme- ly remote period some degree of instinctive love and sym- pathy for his fellows. We are indeed all conscious that we do possess such sympathetic feelings ; 19 but our con- 19 Ilurne remarks (' An Enquiry Concerning the Principles of Morals,' edit, of 3 751, p. 132), "there seems a necessity for confessing that the happiness and misery of others are not spectacles altogether indifferent to us, but that the view of the former . . . communicates a secret joy ; 32 THE DESCENT OF MAN. [Part I sciousness does not tell us whether they are instinctive, having originated long ago in the same manner as with the lower animals, or whether they have been acquired by each of us during our early years. As man is a social animal, it is also probable that he would inherit a ten- dency to be faithful to his comrades, for this quality is common to most social animals. He would in like man- ner possess some capacity for self-command, and perhaps of obedience to the leader of the community. He would from an inherited tendency still be willing to defend, in concert with others, his fellow-men, and would be ready to aid them in any way which did not too greatly inter- fere with his own welfare or his own strong desires. . The social animals which stand at the bottom of the scale are guided almost exclusively, and those which stand higher in the scale are largely guided, in the aid which they give to the members of the same community, by special instincts ; but they are likewise in part impelled by mutual love and sympathy, assisted apparently by some amount of reason. Although man, as just remarked, has no special instincts to tell him how to aid his fellow- men, he still has the impulse, and with his improved in- tellectual faculties would naturally be much guided in this respect by reason and experience. Instinctive sympathy would, also, cause him to value highly the approbation of his fellow-men ; for, as Mr. Bain has clearly shown,20 the love of praise and the strong feeling of glory, and the &till stronger horror of scorn and infamy, " are due to the workings of sympathy." Consequently man would be greatly influenced by the wishes, approbation, and blame of his fellow-men, as expressed by their gestures and lan- guage. Thus the social instincts, which must have been the appearance of the latter . . . throws a melancholy damp over the imagination." 80 'Mental and Moral Science,' 1868, p. 254. Chap. III.] MORAL SENSE. 83 acquired by man in a very rude state, and probably even by his early ape-like progenitors, still give the impulse to many of his best actions ; but his actions are largely de- termined by the expressed wishes and judgment of his fellow-men, and unfortunately still oftener by his own strong, selfish desires. But as the feelings of love and sympathy and the power of self-command become strength- ened by habit, and as the power of reasoning becomes clearer so that man can appreciate the justice of the judg- ments of his fellow-men, he will feel himself impelled, in- dependently of any pleasure or pain felt at the moment, to certain lines of conduct. He may then say, I am the supreme judge of my own conduct, and, in the words of Kant, I will not in my own person violate the dignity of humanity. The more enduring Social Instincts conquer the less Persistent Instincts. — We have, however, not as yet con- sidered the main point, on which the whole question of the moral sense hinges. Why should a man feel that he ought to obey one instinctive desire rather than another ? Why does he bitterly regret if he has yielded to the strong sense of self-preservation, and has not risked his life to save that of a fellow-creature ; or why does he regret having stolen food from severe hunger ? It is evident in the first place, that with mankind the instinctive impulses have different degrees of strength ; a young and timid mother urged by the maternal instinct will, without a moment's hesitation, run the greatest dan- ger for her infant, but not for a mere fellow-creature. Many a man, or even boy, who never before risked his life for another, but in whom courage and sympathy were well developed, has, disregarding the instinct of self-preserva- tion, instantaneously plunged into a torrent to save a drowning fellow-creature. In this case man is impelled 54 THE DESCENT OF MAN [Part I. by the same instinctive motive, which caused the heroic little American monkey, formerly described, to attack the great and dreaded baboon, to save his keeper. Such ac- tions as the above appear to be the simple result of the greater strength of the social or maternal instincts than of any other instinct or motive ; for they are performed too instantaneously for reflection, or for the sensation of pleasure or pain ; though if prevented distress would be caused. I am aware that some persons maintain that actions performed impulsively, as in the above cases, do not come under the dominion of the moral sense, and cannot be called moral. They confine this term to actions done de- liberately, after a victory over opposing desires, or to actions prompted by some lofty motive. But it appears scarcely possible to draw any clear line of distinction of this kind ; though the distinction may be real. As far as exalted motives are concerned, many instances have been recorded of barbarians, destitute of any feeling of general benevolence toward mankind, and not guided by any re- ligious motive, who have deliberately as prisoners sacri- ficed their lives,21 rather than betray their comrades ; and surely their conduct ought to be considered as moral. As far as deliberation and the victory over opposing motives are concerned, animals may be seen doubting bet ween op- posed instincts, as in rescuing their offspring or comrades from danger ; yet their actions, though done for the good of others, are not called moral. Moreover, an action re- peatedly performed by us, will at last be done without deliberation or hesitation, and can then hardly be distin- guished from an instinct ; yet surely no one will pretend that an action thus done ceases to be moral. On the con- 21 I have given one such case, namely, of three Patagonian Indiana who preferred being shot, one after the other, to betraying the plans of their companions in war (' Journal of Researches,' 1845, p. 103). Chap. III.] MORAL SENSE. 85 trary, we all feel that an act cannot be considered as per- fect, or as performed in the most noble manner, unless it be done impulsively, without deliberation or effort, in the same manner as by a man in whom the requisite qualities are innate. He who is forced to overcome his fear or want of sympathy before he acts, deserves, however, in one way higher credit than the man whose innate disposition leads him to a good act without effort. As we cannot distin- guish between motives, we rank all actions of a certain class as moral, when they are performed by a moral being. A moral being is one who is capable of comparing his past and future actions or motives, and of approving or disap- proving of them. We have no reason to suppose that any of the lower animals have this capacity ; therefore when a monkey faces danger to rescue its comrade, or takes charge of an orphan-monkey, we do not call its conduct moral. But in the case of man, who alone can with cer- tainty be ranked as a moral being, actions of a certain class are called moral, whether performed deliberately after a struggle with opposing motives, or from the effects of slowly-gained habit, or impulsively through instinct. But to return to our more immediate subject ; although some instincts are more powerful than others, thus leading to corresponding actions, yet it cannot be maintained that the social instincts are ordinarily stronger in man, or have become stronger through long-continued habit, than the instincts, for instance, of self-preservation, hunger, lust, vengeance, etc. Why, then, does man regret, even though he may endeavor to banish any such regret, that he has followed the one natural impulse, rather than the other ; and why does he further feel that he ought to re- gret his conduct ? Man in this respect differs profoundly from the lower animals. Nevertheless we can, I think, see with some degree of clearness the reason of this dif- ference. 86 THE DESCENT OF MAN. [Paut I. Man, from the activity of his mental faculties, cannot avoid reflection ; past impressions and images are inces- santly passing through his mind with distinctness. Now with those animals which live permanently in a body, the social instincts are ever present and persistent. Such ani- mals are always ready to utter the danger-signal, to de- fend the community, and to give aid to their fellows in accordance with their habits ; they feel at all times, with- out the stimulus of any special passion or desire, some de- gree of love and sympathy for them ; they are unhappy if long separated from them, and always happy to be in their company. So it is with ourselves. A man who pos- sessed no trace of such feelings would be an unnatural monster. On the other hand, the desire to satisfy hunger, or any passion, such as vengeance, is in its nature tempo- rary, and can for a time be fully satisfied. Nor is it easy, perhaps hardly possible, to call up with complete vivid- ness the feeling, for instance, of hunger ; nor, indeed, as has often been remarked, of any suffering. The instinct of self-preservation is not felt except in the presence of danger ; and many a coward has thought himself brave until he has met his enemy face to face. The wish for another man's property is, perhaps, as persistent a desire as any that can be named ; but even in this case the satis- faction of actual possession is generally a weaker feeling than the desire ; many a thief, if not an habitual one, after success has wondered why he stole some article. Thus, as man cannot prevent old impressions contin- ually repassing through his mind, he will be compelled to compare the weaker impressions of, for instance, past hun- ger, or of vengeance satisfied or danger avoided at the cost of other men, with the instinct of sympathy and good- will to his fellows, which is still present, and ever in some degree active in his mind. He will then feel in his imagi- nation that a stronger instinct has yielded to one which Chap. III.] MORAL SENSE. 87 now seems comparatively weak ; and then that sense of dissatisfaction will inevitably be felt with which man is endowed, like every other animal, in order that his in- stincts may be obeyed. The case before given, of the Fwaliow, affords an illustration, though of a reversed na- ture, of a temporary, though for the time strongly persist- ent, instinct conquering another instinct which is usually dominant over all others. At the proper season these birds seem all day long to be impressed with the desire to migrate ; their habits change ; they become restless, are noisy, and congregate in flocks. While the mother-bird is feeding or brooding over her nestlings, the maternal in- stinct is probably stronger than the migratory ; but the instinct which is more persistent gains the victory, and at last, at a moment when her young ones are not in sight, she takes flight and deserts them. When arrived at the end of her long journey, and the migratory instinct ceases to act, what an agony of remorse each bird would feel, if, from being endowed with great mental activity, she could not prevent the image continually passing before her mind of her young ones perishing in the bleak north from cold and hunger ! At the moment of action, man will no doubt be apt to follow the stronger impulse ; and, though this may occa- sionally prompt him to the noblest deeds, it will far more commonly lead him to gratify his own desires at the ex- pense of other men. But after their gratification, when past and weaker impressions are contrasted with the ever- enduring social instincts, retribution will surely come. Man will then feel dissatisfied with^ himself, and will re- solve, with more or less force, to act differently for the fu- ture. This is conscience ; for conscience looks backward and judges past actions, inducing that kind of dissatisfac tion, which, if weak, we call regret, and if severe, remorse These sensations are, no doubt, different from those 88 THE DESCENT OF MAN [Part I. experienced when other instincts or desires are left unsat- isfied ; but every unsatisfied instinct lias its own proper prompting sensation, as we recognize with hunger, thirst, etc. Man thus prompted, will through long habit acquire such perfect self-command, that his desires and passions will at last instantly yield to his social sympathies, and there will no longer be a struggle between them. The still hungry, or the still revengeful man will not think of stealing food, or of wreaking his vengeance. It is possi- ble, or, as we shall hereafter see, even probable, that the habit of self-command may, like other habits, be inherited. Thus at last man comes to feel, through acquired, and, perhaps, inherited habit, that it is best for him to obey his more persistent instincts. The imperious word ought seems merely to employ the consciousness of the existence of a persistent instinct, either innate or partly acquired, serving him as a guide, though liable to be disobeyed. We hardly use the word ought in a metaphorical sense when we say hounds ought to hunt, pointers to point, and re- trievers to retrieve their game. If they fail thus to act, they fail in their duty and act wrongly. If any desire or instinct, leading to an action opposed to the good of others, still appears to a man, when recalled to mind, as strong as, or stronger than, his social instinct, he will feel no keen regret at having followed it ; but he will be conscious that if his conduct were known to his fellows, it would meet with their disapprobation ; and few are so destitute of sympathy as not to feel discomfort when this is realized. If he has no such sympathy, and if his desires leading to bad actions are at the time strong, and when recalled are not overmastered by the persistent so- cial instincts, then he is essentially a bad man ; 22 and the 22 Dr. Prosper Despine, in his ' Psychologic Naturelle,' 1868 (torn. i. p. 243 ; torn. ii. p. 169), gives many curious cases of the worst criminals, who apparently have been entirely destitute of conscience. Chap. III.] MORAL SENSE. 89 sole restraining motive left is the fear of punishment, and the conviction that in the long-run it would be best for his own selfish interests to regard the good of others rather than his own. It is obvious that every one may with an easy con- science gratify his own desires, if they do not interfere with his social instincts, that is, with the good of others ; but in order to be quite free from self-reproach, or at least of anxiety, it is almost necessary for him to avoid the dis- approbation, whether reasonable or not, of his fellow-men. Nor must he break through the fixed habits of his life, es- pecially if these are supported by reason ; for if he does, he will assuredly feel dissatisfaction. He must likewise avoid the reprobation of the one God or gods, in whom, according to his knowledge or superstition, he may be- lieve ; but in this case the additional fear of divine punish- ment often supervenes. The strictly Social Virtues at first alone regarded. — The above view of the first origin and nature of the moral sense, which tells us what we ought to do, and of the con- science which reproves us if we disobey it, accords well with what we see of the early and undeveloped condition of this faculty in mankind. The virtues which must be practised, at least generally, by rude men, so that they may associate in a body, are those which are still recog- nized as the most important. But they are practised al- most exclusively in relation to the men of the same tribe ; and their opposites are not regarded as crimes in relation to the men of other tribes. No tribe could hold together if murder, robbery, treachery, etc., were common ; conse- quently such crimes within the limits of the same tribe ' are branded with everlasting infamy ; " 83 but excite no 23 See an able article in the 'North British Review,' 1867, p. 395. See also Mr. W. Bagehot's articles on the Importance of Obedience and Coho- 5 90 THE DESCENT OF MAN. [Part I. such sentiment beyond these limits. A North -American Indian is well pleased with himself, and is honored by others, when he scalps a man of another tribe ; and a Dyak cuts off the head of an unoffending person and dries it as a trophy. The murder of infants has prevailed on the largest scale throughout the world,24 and has met with no reproach ; but infanticide, especially of females, has been thought to be good for the tribe, or at least not injurious. Suicide during former times was not generally considered as a crime,25 but rather, from the courage displayed, as an honorable act ; and it is still largely practised by some semi-civilized nations without reproach, for the loss to a nation of a single individual is not felt ; whatever the ex- planation may be, suicide, as I hear from Sir J. Lubbock, is rarely practised by the lowest barbarians. It has been recorded that an Indian Thug conscientiously regretted that he had not strangled and robbed- as many travellers as did his father before him. In a rude state of civilization the robbery of strangers is, indeed, generally considered as honorable. The great sin of Slavery has been almost universal, and slaves have often been treated in an infamous manner. As barbarians do not regard the opinion of their women, wives are commonly treated like slaves. Most savages are ut- terly indifferent to the sufferings of strangers, or even de- light in witnessing them. It is well known that the women and children of the North- American Indians aided in tor- turing their enemies. Some savages take a horrid pleasure rence to Primitive Man, in the 'Fortnightly Review,' 1867, p. 529, and 1.868, p. 457, etc. 24 The fullest account which I have met with is by Dr. Gerland, in hia ' Ueber das Aussterben der Naturvolker,' 1868 ; but I shall have to recur to the subject of infanticide in a future chapter. 55 See the very interesting discussion on Suicide in Lecky's ' History of European Morals,' vol. i. 1869, p. 223. Chap. III.] MORAL SENSE. 91 in cruelty to animals,26 and humanity with them is an un- known virtue. Nevertheless, feelings of sympathy and kindness are common, especially during sickness, between the members of the same tribe, and are sometimes extended beyond the limits of the tribe. Mungo Park's touching account of the kindness of the negro women of the inte- rior to him is well known. Many instances could be given of the noble fidelity of savages toward each other, but not to strangers; common experience justifies the maxim of the Spaniard, " Never, never trust an Indian." There cannot be fidelity without truth ; and this funda- mental virtue is not rare between the members of the same tribe; thus Mungo Park heard the negro women teaching their young children to love the truth. This, again, is one of the virtues which becomes so deeply root- ed in the mind that it is sometimes practised by savages, even at a high cost, toward strangers ; but to lie to your enemy has rarely been thought a sin, as the history of modern diplomacy too plainly shows. As soon as a tribe has a recognized leader, disobedience becomes a crime, and even abject submission is looked at as a sacred virtue. As during rude times no man can be useful or faithful to his tribe without courage, this quality has universally been placed in the highest rank; and although in civilized countries a good, yet timid man may be far more useful to the community than a brave one, we cannot help in- stinctively honoring the latter above a coward, however benevolent. Prudence, on the other hand, which does not concern the welfare of others, though a very useful virtue, has never been highly esteemed. As no man can practise the virtues necessary for the welfare of his tribe without self-sacrifice, self-command, and the power of endurance, these qualities have been at all times highly and most 96 See, for instance, Mr. Hamilton's account of the Kaffirs, ' Anthropo logical Review,' 1870, p. xv. 92 THE DESCENT OF MAN. [Part I. justly valued. The American savage voluntarily submits without a groan to the most horrid tortures to prove and strengthen his fortitude and courage ; and we cannot help admiring him, or even an Indian Fakir, who, from a fool- ish religious motive, swings suspended by a hook buried in his flesh. The other self-regarding virtues, which do not obvious- ly, though they may really, affect the welfare of the tribe, have never been esteemed by savages, though now highly appreciated by civilized nations. The greatest intemper- ance with savages is no reproach. Their utter licentious- ness, not to mention unnatural crimes, is something as- tounding.27 As soon, however, as marriage, whether po- lygamous or monogamous, becomes common, jealousy will lead to the inculcation of female virtue ; and this being honored, Avill tend to spread to the unmarried females. How slowly it spreads to the male sex we see at the pres- ent day. Chastity eminently requires self-command, there- fore it has been honored from a very early period in the moral history of civilized man. As a consequence of this, the senseless practice of celibacy has been ranked from a remote period as a virtue.28 The hatred of indecency, which appears to us so natural as to be thought innate, and which is so valuable an aid to chastity, is a modern virtue, appertaining exclusively, as Sir G. Staunton re- marks,29 to civilized life. This is shown by the ancient religious rites of various nations, by the drawings on the walls of Pompeii, and by the practices of many savages. We have now seen that actions are regarded by sav- ages, and were probably so regarded by primeval man, as good or bad, solely as they affect in an obvious manner 2: Mr. M'Lennan has given (' Primitive Marriage,' 1865, p. 1*76) a good collection of facts on this head. 28 Lecky, 'History of European Morals,' vol. i. 1809, p. 109. 89 ' Embassy to China,' vol. ii. p. 348. Chap. III.] MORAL SENSE. 93 the welfare of the tribe — not that of the species, nor that of man as an individual member of the tribe. This con- clusion agrees well with the belief that the so-called moral sense is aboriginally derived from the social instincts, for both relate at first exclusively to the community. The chief causes of the low morality of savages, as judged by our standard, are, firstly, the confinement of sympathy to the same tribe. Secondly, insufficient powers of reasoning, so that the bearing of many virtues, especially of the self- regarding virtues, on the general welfare of the tribe is not recognized. Savages, for instance, fail to trace the multiplied evils consequent on a want of temperance, chastity, etc. And, thirdly, weak power of self-command ; for this power has not been strengthened through long-con- tinued, perhaps inherited, habit, instruction, and religion. I have entered into the above details on the immo- rality of savages,30 because some authors have recently taken a high view of their moral nature, or have attrib- uted most of their crimes to mistaken benevolence.31 These authors appear to rest their conclusion on savages possessing, as they undoubtedly do possess, and often in a high degree, those virtues which are serviceable, or even necessary, for the existence of a tribal community. Concluding Remarks. — Philosophers of the derivative school of morals formerly assumed that the foundation of morality lay in a form of Selfishness ; but more recently in the " Greatest Happiness principle." According to the view given above, the moral sense is fundamentally iden- 20 See on this subject copious evidence in Chap. vii. of Sir J. Lub- bock, 'Origin of Civilization,' 18*70. 31 For instance Lecky, 'Hist. European Morals,' vol. i. p. 124. 82 This term is used in an able article in the » Westminster Review,' Oct. 1869, p. 493. For the Greatest Happiness principle, see J. S. Mill, Utilitarianism,' p. 17. 91 THE DESCENT OF MAN. [Part I. tical with the social instincts; and in the case of the lower animals it would be absurd to speak of these in- stincts as having been developed from selfishness, or for the happiness of the community. They have, however, certainly been develoj>ed for the general good of the com- munity. The term, general good, may be defined as the means by which the greatest possible number of individuals can be reared in full vigor and health, with all their facul- ties perfect, under the conditions to which they are exposed. As the social instincts both of man and the lower animals have no doubt been developed by the same steps, it would be advisable, if found practicable, to use the same defini- tion in both cases, and to take, as the test of morality, the general good or welfare of the community, rather than the general happiness ; but this definition would perhaps re- quire some limitation on account of political ethics. When a man risks his life to save that of a fellow- creature, it seems more appropriate to say that he acts for the general good or welfare, rather than for the general happiness of mankind. No doubt the welfare and the happiness of the individual usually coincide ; and a con- tented, happy tribe will flourish better than one that is discontented and unhappy. We have seen that, at an early period in the history of man, the expressed wishes of the community will have naturally influenced to a large extent the conduct of each member ; and as all wish for happiness, the " greatest happiness principle " will have become a most important secondary guide and object ; the social instincts, including sympathy, always serving as the primary impulse and guide. Thus the reproach of lay- ing the foundation of the most noble part of our nature in the base principle of selfishness is removed; unless indeed the satisfaction which every annual feels when it follows its proper instincts, and the dissatisfaction felt when pre- vented, be called selfish. Chap. Ill] MORAL SENSE. 95 The expression of the wishes and judgment of the members of the same community, at first by oral and afterward by written language, serves, as just remarked, as a most important secondary guide of conduct, in aid of the social instincts, but sometimes in opposition to them. This latter fact is well exemplified by the Law of Honor \ that is the law of the opinion of our equals, and not of all our countrymen. The breach of this law, even when the breach is known to be strictly accordant with true moral- ity, has caused many a man more agony than a real crime. We recognize the same influence in the burning sense of shame which most of us have felt even after the interval of years, when calling to mind some accidental breach of a trifling though fixed rule of etiquette. The judgment of the community will generally be guided by some rude experience of what is best in the long-run for all the members ; but this judgment will not rarely err from ignorance and from weak powers of reasoning. Hence the strangest customs and superstitions, in complete opposi- tion to the true welfare and happiness of mankind, have become all-powerful throughout the world. We see this in the horror felt by a Hindoo who breaks his caste, in the shame of a Mahometan woman who exposes her face, and in innumerable other instances. It would be difficult to distinguish between the remorse felt by a Hindoo who has eaten unclean food, from that felt after committing a theft ; but the former would probably be the more severe. How so many absurd rules of conduct, as well as so many absurd religions beliefs, have originated we do not know ; nor how it is that they have become, in all quar- ters of the world, so deeply impressed on the mind of men; but it is worthy of remark that a belief constantly inculcated during the early years of life, while the brain is impressible, appears to acquire almost the nature of an instinct ; and the very essence of an instinct is that it is 96 THE DESCENT OF MAN. [Parti. followed independently of reason. Neither can we say why certain admirable virtues, such as the love of truth, are much more highly appreciated by some savage tribes than by others ; 33 nor, again, why similar differences pre- vail even among civilized nations. Knowing how firmly fixed many strange customs and superstitions have be- come, we need feel no surprise that the self-regarding virtues should now appear to us so natural, supported as they are by reason, as to be thought innate, although they were not valued by man in his early condition. Notwithstanding many sources of doubt, man can generally and readily distinguish between the higher and lower moral rules. The higher are founded on the social instincts, and relate to the welfare of others. They are supported by the approbation of our fellow-men and by reason. The lower rules, though some of them when im- plying self-sacrifice hardly deserve to be called lower, relate chiefly to self, and owe their origin to public opinion, when matured by experience and cultivated ; for they are not practised by rude tribes. As man advances in civilization, and small tribes are united into larger communities, the simplest reason would tell each individual that he ought to extend his social in- stincts and sympathies to all the members of the same nation, though personally unknown to him. This point being once reached, there is only an artificial barrier to prevent his sympathies extending to the men of all nations and races. If, indeed, such men are separated from him by great differences in appearance or habits, experience unfortunately shows us how long it is before we look at them as our fellow-creatures. Sympathy beyond the con- fines of man, that is, humanity to the lower animals, seems 33 Good instances are given by Mi. Wallace in 'Scientific Opinion,1 Sept. 15, 1869; and mnro, fully in his 'Contributions to the Theory of Natural Selection,' 1870, p. 353. Chap. III.] MORAL SENSE. 97 to be one of the latest moral acquisitions. It is apparently unfelt by savages, except toward their pets. How little the old Romans knew of it is shown by their abhorrent gladiatorial exhibitions. The very idea of humanity, as far as I could observe, was new to most of the Gauchos of the Pampas. This virtue, one of the noblest with which man is endowed, seems to arise incidentally from our sym- pathies becoming more tender and more widely diffused, until they are extended to all sentient beings. As soon as this virtue is honored and practised by some few men, it spreads through instruction and example to the young, and eventually through public opinion. The highest stage in moral culture at which we can arrive, is when we recognize that we ought to control our thoughts, and "not even in inmost thought to think again the sins that made the past so pleasant to us." 34 What- ever makes any bad action familiar to the mind, renders its performance by so much the easier. As Marcus Aure- lius long ago said, " Such as are thy habitual thoughts, such also will be the character of thy mind; for the soul is dyed by the thoughts." 35 Our great philosopher, Herbert Spencer, has recently explained his views on the moral sense. He says : 36 " I believe that the experiences of utility organized and con- solidated through all past generations of the human race, have been producing corresponding modifications, which, by continued transmission and accumulation, have become in us certain faculties of moral intuition — certain emotions responding to right and wrong conduct, which have no apparent basis in the individual experiences of utility." 34 Tennyson, ' Idylls of the King,' p. 244. 35 ' The Thoughts of the Emperor M. Aurelius Antoninus,' Eng. trans, atioc, 2d edit., 1889, p. 112. Marcus Aurelius was born a. d. 121. 36 Letter to Mr. Mill in Bain's ' Mental and Moral Science,' 1868, p 722. 98 THE DESCENT OF MAN. [Part I. There is not the least inherent improbability, as it seems to me, in virtuous tendencies being more or less strongly inherited ; for, not to mention the various dispositions and habits transmitted by many of our domestic animals, I have heard of cases in which a desire to steal and a ten- dency 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 three 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 of man- kind. We have, however, as yet, hardly sufficient evi- dence 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 ap- pears probable, at least in such cases as chastity, temper- ance, humanity to animals, etc., that they become first im- pressed on the mental organization through habit, instruc- tion, and example, continued during several generations in the same family, and in a quite subordinate degree, or not at all, by the individuals possessing such virtues, having succeeded best in the struggle for life. My chief source of doubt with respect to any such inheritance, is that senseless customs, superstitions, and tastes, such as the horror of a Hindoo for unclean food, ought on the same principle to be transmitted. Although this in itself is perhaps not less probable 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 Chap. III.] MORAL SENSE. 99 of the transmission of superstitious customs or senseless habits. Finally, the social instincts which no doubt were ac- quired by man, as by the lower animals, for the good of the community, will from the first have given to him some wish to aid his fellows, and some feeling of sym- pathy. Such impulses will have served him at a very early period as a rude rule of right and wrong. But as man gradually advanced in intellectual power and was enabled to trace the more remote consequences of his ac- tions ; as he acquired sufficient knowledge to reject bane- ful customs and superstitions ; as he regarded more and more not only the welfare but the happiness of his fellow- men; as from habit, following on beneficial experience, instruction, and example, his sympathies became more tender and widely diffused, so as to extend to the men .of all races, to the imbecile, the maimed, and other use- less members of society, and finally to the lower ani- mals— so would the standard of his morality rise higher and higher. And it is admitted by moralists of the de- rivative school and by some intuitionists, that the stand- ard of morality has risen since an early period in the his- tory of man.37 As a struggle may sometimes be seen going on between the various instincts of the lower animals, it is not sur- prising that there should be a struggle in man between his social instincts, with their derived virtues, and his lower, though, at the moment, stronger impulses or desires. This, as Mr. Galton38 has remarked, is all the less sur- 37 A writer in the 'North British Review ' (July, 18G9, p. 531), well capable of forming a sound judgment, expresses himself strongly to this effect. Mr. Lecky (' Hist, of Morals,' vol. i. p. 143) seems to a certain extent to coincide. 86 See his remarkable work on 'Hereditary Genius,' 1869, p. 349. 100 THE DESCENT OF MAN. [Part L prising, 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 dissatisfac- tion, analogous to that felt from other unsatisfied 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, per- haps 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 last two 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 an- thropomorphous ape, if he could take a dispassionate view of his own case, would admit that though he could form an artful plan to plunder a garden — -though he could use stones for fighting or for breaking open nuts, yet that the thought of fashioning a stone into a tool was quite beyond his scope. Still less, as he would admit, could he follow out a train of metaphysical reasoning, or solve a mathe- matical problem, or reflect on God, or admire a grand natural scene. Some apes, however, would probably de- clare that they could and did admire the beauty of the col- ored 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 The Duke of Argyll ('Primeval Man,' 1869, p. 188) has some good re- marks on the contest in man's nature between right and wrong. Chap. III.] MORAL SENSE. 101 wants, the notion of expressing definite ideas by definite sounds had never crossed their minds. They might insist that they were ready to aid their fellow-apes of the same troop in many ways, to risk their lives for them, and to take charge of their orphans ; but they would be forced to acknowledge that disinterested love for all living creatures, the most noble attribute of man, was quite beyond their comprehension. Nevertheless the difference in mind between man and the higher animals, great as it is, is certainly one of degree and not of kind. We have seen that the senses and intui- tions, the various emotions and faculties, such as love, memory, attention, curiosity, imitation, reason, etc., of which man boasts, may be found in an incipient, or even sometimes in a well-developed condition, in the lower ani- mals. They are also capable of some inherited improve- ment, as we see in the domestic dog compared with the wolf or jackal. If it be maintained that certain powers, such as self-consciousness, abstraction, etc., are peculiar to man, it may well be that these are the incidental results of other highly-advanced 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 infant possess the power of abstraction, or become self-conscious and reflect on its own existence ? We can- not answer ; nor can we answer in regard to the ascending organic scale. The half-art and half-instinct of language still bears the stamp of its gradual evolution. The en- nobling belief in God is not universal with man ; and the belief in active spiritual agencies naturally follows 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 endeavored to show that the social instincts — the prime principle of man's moral consti- 102 THE DESCENT OF MAN. [Part! tution " — 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 like- wise ; " 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 gradation from the mind of an utter idiot, lower than that of the lowest animal, to the mind of a Newton. 89 'The Thoughts of Marcus Aurelius,' etc., p. 139. ','nAP. IV. 1 MANNER OF DEVELOPMENT. 103 CHAPTER IV. ON THE MANNER OF DEVELOPMENT OF MAN FROM SOME LOWER FORM. Variability of Body and Mind in Man. — Inheritance.— Causes of Varia- bility.— 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. — Eeversion. — Cor- related Variation. — Eate of Increase. — Checks to Increase. — Natural Selection. — Man the most Dominant Animal in the "World. — Impor- tance of his Corporeal Structure. — The Causes which have led to his becoming erect. — Consequent Changes of Structure. — Decrease in Size of the Canine Teeth. — Increased Size and Altered Shape of the Skull. — Nakedness. — Absence of a Tail. — Defenceless Condition of Man. 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 ob- jection to this conclusion. In order that an ape-like crea- ture should have been transformed into man, it is neces- sary that this early form, as well as many successive links, should all have varied in mind. and body. It is impossible to obtain direct evidence on this" head ; but if it can be shown that man now varies — that his variations are in- duced by the same general causes, and obey the same general laws, as in the case of the lower animals — there can be little doubt that the preceding intermediate links J 04 THE DESCENT OF MAN. [Part I. varied in a like manner. The variations at each succes- sive stage of descent must, also, have been in some man- ner accumulated and fixed. 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 following 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 be preferred. It is manifest that man is now subject to much varia- bility. ~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 pre- vails, 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 con- fined an area as the Sandwich Islands.2 An eminent den- tist assures me that there is nearly as much diversity in the teeth as in the features. The chief arteries so fre- quently run in abnormal courses, that it has been found useful for surgical purposes to calculate from 12,000 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. Aitken Meigs in 'Proc. Acad. Nat. Sci.' Philadelphia, May, 1866. On the Australians, see Huxley, in Ly ell's 'Antiquity of Man,' 1863, p. 87. On the Sandwich Islanders, Prof. J. Wyman, ' Observations on Crania,' Boston. 1868, p. 18. Chap. IV.] MANNER OF DEVELOPMENT. 105 corpses how often each course prevails.3 The muscles are eminently variable ; thus those of the foot were found by- Prof. Turner 4 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 ap- propriate movements must have been modified in accord- ance with the several deviations. Mr. J. Wood has re- corded6 the occurrence of 295 muscular variations in thirty-six subjects, and in another set of the same number no less than 558 variations, reckoning both sides of the body as one. In the last set, not one body out of the thirty-six was " found totally wanting in departures from the standard descriptions of the muscular system given in anatomical text-books." A single body presented the extraordinary number of twenty-five distinct abnormali- ties. The same muscle sometimes varies in many ways : thus Prof. Macalister describes 8 no less than twenty dis- tinct variations in the palmar is access orius. The famous old anatomist, Wolff,7 insists that the in- ternal viscera are more variable than the external parts : Nulla particula est qum non allter et aliter in aliis se habeat hominibus. He has even written a treatise on the choice of typical examples of the viscera for representation. A discussion on the beau-ideal of the liver, lungs, kidneys, etc., as of the human face divine, sounds strange in our ears. The variability or diversity of the mental faculties in men of the same race, not to mention the greater differ- ences between the men of distinct races, is so notorious 3 ' Anatomy of the Arteries,' by R. Quaim 4 'Transact. Royal Soc.' Edinburgh, vol. xxiv. pp. 175, 1S9. 5 'Proc. Royal Soc.' 1867, p. 544 ; also 1868, pp. 483, 524. There in a previous paper, 1866, p. 229. 6 'Proc. R. Irish Academy,' vol. x. 1868, p. 141. 7 'Act. Acad.,' St. Petersburg, 1778, part ii. p. 217 106 THE DESCENT OF MAN. [Part 1 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 in- dividual monkey of those which he kept under confine- ment in Africa had its own peculiar disposition and tem- per : he mentions one baboon remarkable for its high in- telligence; and the keepers in the Zoological Gardens pointed out to me a monkey, belonging to the New World division, equally remarkable for intelligence. Rengger, also, insists on the diversity in the various mental charac- ters 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.8 I have elsewhere9 so fully discussed the subject of In- heritance that I need here add hardly any thing. 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 trans- mission is manifest in our dogs, horses, and other domes- tic animals. Besides special tastes and habits, general in- telligence, courage, bad and good temper, etc., are cer- tainly transmitted. With man we see similar facts in al- most every family ; and we now know through the admi- rable labors of Mr. Galton 10 that genius, which implies a 8 Brekm, ' Thierleben/ B. i. s. 58, 87. Rengger, 'Saugethiere you Paraguay,' s. 57. 9 ' Variation of Animals and Plants under Domestication,' vol. ii. chap xii. 10 ' Hereditary Genius : an Inquiry into its Laws and Consequences,* 1869. Chap. IV.] MANNER OF DEVELOPMENT. 10 7 wonderfully complex combination 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 all cases very ignorant ; but we can see that in man as in the lower animals, they stand in some relation with the con- ditions to which each species has been exposed during several generations. Domesticated animals vary more than those in a state of nature ; and this is apparently due to the diversified and changing nature of their conditions. The different races of man resemble in this respect domes- ticated animals, and so do the individuals of the same race when inhabiting a very wide area, like that of America. We see the influence of diversified conditions in the more civilized nations, the members of which be- long to different grades of rank and follow different occu- pations, 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 domesti- cated " 12 than any other animal. Some savage races, such as the Australians, are not exposed to more diversified conditions than are many species which have very wide ranges. In another and much more important respect, man differs widely from any strictly-domesticated animal; 11 Mr. Bates remarks (' The Naturalist on the Amazons,' 18G3, vol. ii. p. 159), with respect to '♦.he Indians of the same South- American tribe, u No 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 cheels, spread of nostrils, and obliquity of tyes." 12 Bluiuenbach, 'Treatises on Anthropolog.' Eng. translate 1865, p. 205.' X08 THE DESCENT OF MAN. [Part I. • for his breeding has not been controlled, either through methodical or unconscious selection. No race or body of men has oeen so completely subjugated by other men, that certain individuals have been preserved and thus un- consciously selected, from being in some way more useful to their masters. Nor have certain male and female in- dividuals been intentionally picked out and matched, ex- cept in the well-known case of the Prussian grenadiers ; and in this case man obeyed, as might have been expect- ed, the law of methodical 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 restricted ranges ; and the variability of man may with more truth be com- pared with that of widely-ranging species, than with that of domesticated animals. * Not only does variability appear to be induced in man and the lower animals by the same general causes, but in both the same characters are affected in a closely analo- gous manner. This has been proved in such full detail by Godron and Quatrefages, that I need here only refer to their works.13 Monstrosities, which graduate into slight variations, are likewise so similar in man and the lower animals, that the same classification and the same terms can be used for both, as may be seen in Isidore Geoffroy St.-Hilaire's great work.14 This is a necessary 13 Godron, ' De l'Espece,' 1859, torn. ii. livre 3. Quatrefages, • Unite de l'Espece Humaine,' 1861. Also Lectures on Anthropology, given in the 'Revue des Cours Scientifiques,' 1866-1868. 14 • Hist. Gen. et Part, des Anomalies de l'Organisation,' in three vol umes, torn. i. 1832. Chap. IV.] MANNER OF. DEVELOPMENT. 109 - consequence of the same laws of change prevailing throughout the animal kingdom. In my work on the variation of domestic animals, I have attempted to ar- range in a rude fashion the laws of variation under ■the following heads: The direct and definite action of changed conditions, as shown by all or nearly all the in- dividuals of the same species varying in the same manner under the same circumstances. The effects of the long- continued use or disuse of parts. The cohesion of homol- ogous parts. The variability of multiple parts. Com- pensation of growth; but of this law I have found no good instances in the case of man. The effects of the me- chanical pressure of one part on another ; as of the pelvis on the cranium of the infant in the womb. Arrests of de- velopment, 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 ani- mals; and most of them even to plants. It would be superfluous here to. discuss all of them ; 15 but several are so important 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 that changed conditions produce some effect, and occa- sionally a considerable effect, on organisms of all kinds : and it seems at first probable that, if sufficient time were allowed, this would be the invariable result. But I have failed to obtain clear evidence in favor of this conclusion ; and valid reasons may be urged on the other side, at least 15 1 have fully discussed these laws in my ' Variation of Animals and Plants under Domestication,' vol. ii. chaps, xxii. and xxiii. M. J. P. Durand has lately (18G8) published a valuable essay, 'D© l'lnfluence dea Milieux,' etc. He lays much stress on the nature of the soil. UO THE DESCENT OF MAN. [Pari I. as far as the innumerable structures are concerned, which are adapted for special ends. There can, however, be no doubt that changed conditions induce an almost indefinite amount of fluctuating variability, by which the whole or- ganization is rendered in some degree plastic. In the United States, above 1,000,000 soldiers, who served in the late war, were measured, and the States in which they were born and reared recorded.16 From this astonishing number of observations it is proved that local influences of some kind act directly on stature ; and we further learn that " the State where the physical growth has in great measure taken place, and the State of birth, which indicates the ancestry, seem to exert a marked in- fluence on the stature." For instance, it is established, " that residence in the Western States, during the years of growth, tends to produce increase of stature." On the other hand, it is certain that with sailors, their manner of life delays growth, as shown " by the great difference be- tween the statures of soldiers and sailors at the ages of seventeen and eighteen years." Mr. B. A. Gould en- deavored to ascertain the nature of the influences which thus act on stature; but he arrived only at negative results, namely, that they did not relate to climate, the elevation of the land, soil, or even "in any controlling degree " to the abundance or need of the comforts of life. This latter conclusion is directly opposed to that arrived at by Villerme from the statistics of the height of the con- scripts in different parts of France. "When we compare the differences in stature between the Polynesian chiefs and the lower orders within the same islands, or between the inhabitants of the fertile volcanic and low barren coral islands of the same ocean,17 or again between the 16 'Investigations in Military and Anthrop. Statistics,' etc., 1869, by B. A. Gould, pp. 93, 107, 126, 131, 134. 17 For the Polynesians, see Prichard's ' Physical Hist, of Mankind,' Chap. IV.l MANNER OF DEVELOPMENT. m Fuesrians on the eastern and western shares of their country, where the means of subsistence are very dif- ferent, it is scarcely possible to avoid the conclusion that better food and greater comfort do influence stature. But the preceding statements show how difficult it is to arrive at any precise result. Dr. Beddoe has lately proved that, with the inhabitants of Britain, residence in town and certain occupations have a deteriorating in- fluence on height ; and he infers that the result is to a certain extent inherited, as is likewise the case in the United States. Dr. Beddoe further believes that wherever a " race attains its maximum of physical development, it rises highest in energy and moral vigor." 18 Whether external conditions produce any other direct effect on man is not known. It might have been expected that differences of climate would have had a marked in- fluence, as the lungs and kidneys are brought into fuller activity under a low temperature, and the liver and skin under a high one.19 It was formerly thought that the color of the skin and the character of the hair were de- termined by light or heat ; and although it can hardly be denied that some effect is thus produced, almost all ob- servers now agree that the effect has been very small, even after exposure during many ages. But this subject will be more properly discussed when we treat of the dif- ferent races of mankind. With our domestic animals there are grounds for believing that cold and damp direct- ly affect the growth of the hair ; but I have not met with any evidence on this head in the case of man. vol. v. 1847, pp. 145, 283. Also Godron, 'Do l'Espece,' torn. ii. p. 289. There is also a remarkable difference in appearance between the closely- allied Hindoos inhabiting the Upper Ganges and Bengal ; see Elphin- Btone's 'History of India,' vol. i. p. 324. 13 Memoirs, ' Anthropolog. Soc' vol. iii. 1867-'69, pp. 5G1, 565, 567. 19 Dr. Brakenridge, ' Theory of Diathesis,' 'Medical Times,' June 19 and July 17, 1869. 112 THE DESCENT OF MAN. [Pakt I. Effects of the increased Use and Disuse of Parts. — It is well known that use strengthens the muscles in the individual, and complete disuse, or the destruction of the proper nerve, weakens them. When the eye is destroyed the optic nerve often becomes atrophied. When an artery is tied, the lateral channels increase not only in diameter, but in the thickness and strength of their coats. When one kidney ceases acting from disease, the other increases in size and does double work. Bones increase not only in thickness, but in length, from carrying a greater weight.20 Different occupations habitually followed lead to changed proportions in various parts of the body. Thus it was clearly ascertained by the United States Commission21 that the legs of the sailors employed in the late war were longer by 0.217 of an inch than those of the soldiers, though the sailors were on an average shorter men ; while their arms were shorter by 1.09 of an inch, and therefore out of proportion shorter in relation to their lesser height. This shortness of the arms is apparently due to their greater use, and is an unexpected result ; but sailors chiefly use their arms in pulling and not in sup- porting weights. The girth of the neck and the depth of the instep are greater, while the circumference of the chest, waist, and hips, is less in sailors than in soldiers. Whether the several foregoing modifications would be- come hereditary, if the same habits of life were followed during many generations, is not known, but is probable. Rengger 22 attributes the thin legs and thick arms of the Payaguas Indians to successive generations having passed 20 1 have given authorities for these several statements in my ' Varia- tion of Animals under Domestication,' vol. ii. pp. 297-300. Dr. Jaeger, " Ueber das Langenwachsthum dor Knochen," ' Jenaischen Zeitschrift,' B. v. Heft i. 21 'Investigations,' etc. By B. A. Gould, 1869, p. 288. 2£ ' Siiugethiere von Paraguay,' 1830, s. 4. Chap. IV.] MANNER AND DEVELOPMENT. 113 nearly their whole lives in canoes, with their lower extremities motionless. Other writers have come to a similar conclusion in other analogous cases. According to Cranz,23 who lived for a long time with the Esquimaux, " the natives believe that ingenuity and dexterity in seal- catching (their highest art and virtue) is hereditary; there is really something in it, for the son of a celebrated seal- catcher will distinguish himself though he lost his father in childhood." But in this case it is mental aptitude, quite as much as bodily structure, which appears to be inherited; It is asserted that the hands of English labor- ers are at birth larger than those of the gentry.24 From the correlation which exists, at least in some cases,25 be- tween the development of the extremities and of the jaws, it is possible that in those classes which do not labor much with their hands and feet, the jaws would be reduced in size from this cause. That they are generally smaller in refined and civilized men than in hard-working men or savages, is certain. But with savages, as Mr. Herbert SjDencer26 has remarked, the greater use of the jaws in chewing coarse, uncooked food, would act in a direct man- ner on the masticatory muscles and on the bones to which they are attached. In infants long before birth, the skin on the soles of the feet is thicker than on any other part of the body ; 27 and it can hardly be doubted that this is due to the inherited effects of pressure during a long series of generations. It is familiar to every one that watchmakers and en- gravers are liable to become short-sighted, while sailors and especially savages are generally long-sighted. Short- 23 'History of Greenland,' Eng. translat. 1*767, vol. i. p. 230. 24 « Intermarriage.' By Alex. Walker, ] 838, p. 377. 25 'The Variation of Animals under Domestication,' vol. i. p. 173 26 ' Principles of Biology,' vol. i. p. 455. ,7 Paget, 'Lectures on Surgical Pathology,' vol. i. 1853, p. 209. 6 114 THE DESCENT OF MAN. [Fart L Bight and long-sight certainly tend to be inherited.28 The inferiority of Europeans, in comparison with savages, in eye-sight and in the other senses, is no doubt the accumu- lated and transmitted effect of lessened use during many generations ; for Kengger 29 states that he has repeatedly observed Europeans, who had been brought up and spent their whole lives with the wild Indians, who nevertheless did not equal them in the sharpness of their senses. The same naturalist observes that the cavities in the skull for the reception of the several sense-organs are larger in the American aborigines than in Europeans ; and this no doubt indicates a corresponding difference in the dimen- sions of the organs themselves. Blumenbach has also re- marked on the large size of the nasal cavities in the skulls of the American aborigines, and connects this fact with their remarkably acute power of smell. The Mongolians of the plains of Northern Asia, according to Pallas, have wonderfully perfect senses ; and Prichard believes that the great breadth of their skulls across the zygomas follows from their highly-developed sense-organs.30 The Quechua Indians inhabit the lofty plateaux of Peru, and Alcide d'Orbigny states 31 that from continually breathing a highly rarefied atmosphere they have acquired chests and lungs of extraordinary dimensions. The cells, 28 ' The Variation of Animals under Domestication,' vol. ii. p. 8. 29 ' Siiugefhiere von Paraguay,' s. 8, 10. I have had good opportuni- ties for observing the extraordinary power of eyesight in the Fuegians. See also Lawrence ('Lectures on Physiology,' etc., 1822, p. 404) on this same subject. M. Giraud-Teulon has recently collected ('Revue des Cours Scientifiques,' 18*70, p. 625) a large and valuable body of evidence proving that the cause of short-sight, " Cest le travail assidu, depres." 30 Prichard, ' Phys. Hist, of Mankind,' on the authority of Blumen- bach, vol i. 1851, p. 311 ; for the statement by Pallas, vol. iv. 1844, p, 407. 81 Quoted by Prichard, ' Researches into the Phys. Hist, of Mankind, rol. v. p. 463. Chap. IV.] MANNER OF DEVELOPMENT. 115 also, of the lungs are larger and more numerous than in Europeans. These observations have been doubted ; but Mr. D. Forbes carefully measured many Aymaras, an allied race, living at the height of between ten and fifteen thou- sand feet ; and he informs me 32 that they differ conspicu- ously from the men of all other races seen by him, in the circumference and length of their bodies. In his table of measurements, the stature of each man is taken at 1,000, and the other measurements are reduced to this standard. It is here seen that the extended arms of the Aymaras are shorter than those of Europeans, and much shorter than those of Negroes. The legs are likewise shorter, and they present this remarkable peculiarity, that in every Aymara measured the femur is actually shorter than the tibia. On an average the length of the femur to that of the tibia is as 211 to 252 ; while in two Europeans measured at the same time, the femora to the tibise were as 244 to 230 ; and in three Negroes as 258 to 241. The humerus is like- wise shorter relatively to the forearm. This shortening of that part of the limb which is nearest to the body, ap- pears to be, as suggested to me by Mr. Forbes, a case of compensation in relation with the greatly-increased length of the trunk. The Aymaras present some other singular points of structure, for instance, the very small projection of the heel. These men are so thoroughly acclimatized to their cold and lofty abode, that when formerly carried down by the Spaniards to the low eastern plains, and when now tempt- ed down by high wages to the gold-washings, they suffer a frightful rate of mortality. Nevertheless, Mr. Forbes found a few pure families which had survived during two generations ; and he observed that they still inherited their characteristic peculiarities. But it was manifest, 32 Mr. Forbes' s valuable paper is now published in the ' Journal of tho Ethnological Soc. of London,' new series, vol. ii. 1870, p. 193. 116 THE DESCENT OF MAN. [Part I. even without measurement, that these peculiarities had all decreased ; and on measurement their bodies were found not to be so much elongated as those of the men on the high plateau ; while their femora had become somewhat lengthened, as had their tibiae, but in a less degree. The actual measurements may be seen by consulting Mr. Forbes's memoir. From these valuable observations, there can, I think, be no doubt that residence during many gen- erations at a great elevation tends, both directly and indi- rectly, to induce inherited modifications in the proportions of the body.33 Although man may not have been much modified dur- ing the latter stages of his existence through the increased or decreased use of parts, the facts now given show that his liability in this respect has not been lost ; and we posi- tively know that the same law holds good with the lower animals. Consequently we may infer that, when at a re- mote epoch the progenitors of man were in a transitional state, and were changing from quadrupeds into bipeds, natural selection would probably have been greatly aided by the inherited effects of the increased or diminished use of the different parts of the body. Arrests of Development. — Arrested development dif- fers from arrested growth, as parts in the former state continue to grow while still retaining their early condi- tion. Various monstrosities come under this head, and some are known to be occasionally inherited, as a cleft- palate. It will suffice for our purpose to refer to the arrested brain-development of microcephalous idiots, as described in Vogt's great memoir.34 Their skulls are 33 Dr. Wilckens (' Landwirthschaft. Woehenblatt,' No. 10, 1869) has lately published an interesting essay showing how domestic animals, which live in mountainous regions, have their frames modified. 84 'Memoire sur les Microcephales,' 1867, pp. 50, 125, 169, 171, 184, 198. Chap. IV.] MANNER OF DEVELOPMENT. iif smaller, and the convolutions of the brain are less com- plex, than in normal men. The frontal sinus, or the pro- jection over the eyebrows, is largely developed, and the jaws are prognathous to an " effrayant " degree ; so that these idiots somewhat resemble the lower types of man- kind. Their intelligence and most of their mental facul- ties are extremely feeble. They cannot acquire the power of speech, and are wholly incapable of prolonged atten- tion, but are much given to imitation. They are strong and remarkably active, continually gambolling and jump- ing about, and making grimaces. They often ascend stairs on all-fours ; and are curiously fond of climbing up furniture or trees. We are thus reminded of the delight shown by almost all boys in climbing trees ; and this again reminds us how lambs and kids, originally alpine animals, delight to frisk on any hillock, howevei small. Reversion. — Many of the cases to be here given might have been introduced under the last heading. Whenever a structure is arrested in its development, but * still con- tinues growing until it closely resembles a corresponding structure in some lower and adult member of the same group, we may in one sense consider it as a case of rever- sion. The lower members in a group give us some idea how the common progenitor of the group was probably constructed ; and it is hardly credible that a part arrested at an early phase of embryonic development should be enabled to continue growing so as ultimately to perform its proper function, unless it had acquired this power of continued growth during some earlier state of existence, when the present exceptional or arrested structure was normal. The simple brain of a microcephalous idiot, in as far as it resembles that of an ape, may in this sense be said to offer a case of reversion. There are other cases which come more strictly under our present heading of [18 THE DESCENT OF MAN. [Part i; reversion. Certain structures, regularly occurring in the lower members of the group to which man belongs, occa- sionally make their appearance in him, though not found in the normal human embryo ; or, if present in the nor- mal human embryo, they become developed in an abnor- mal manner, though this manner of development is proper to the lower members of the same group. These remarks will be rendered clearer by the following illustrations. In various mammals the uterus graduates from a double organ with two distinct orifices and two passages, as in the marsupials, into a single organ, showing no signs of double- ness except a slight internal fold, as in the higher apes and man. The rodents exhibit a perfect series of gradations between these two extreme states. In all mammals the uterus is developed from two simple primitive tubes, the inferior portions of which form the cornua ; and it is in the words of Dr. Farre " by the coalescence of the two cornua at their lower extremities that the body of the uterus is formed in man ; while in those animals in which no middle portion or body exists, the cornua remain un- united. As the development of the uterus proceeds, the two cornua become gradually shorter, until at length they are lost, or, as it were, absorbed into the body of the uterus." The angles of the uterus are still produced into cornua, even so high in the scale as in the lower apes, and their allies the lemurs. Now in women anomalous cases are not very infre- quent, in which the mature uterus is furnished with cor- nua, or is partially divided into two organs ; and such cases, according to Owen, repeat "the grade of concen- trative development," attained by certain rodents. Here perhaps we have an instance of a simple arrest of embry- onic development, with subsequent growth and perfect functional development, for either side of the partially double uterus is capable of performing the proper office Chap. IV.] MANNER OF DEVELOPMENT. 119 of gestation. In other and rarer cases, two distinct uter- ine cavities are formed, each having its proper orifice and passage.36 No such stage is passed through during the ordinary development of the embryo, and it is difficult to believe, though perhaps not impossible, that the two sim- ple, minute, primitive tubes could know how (if such an expression may be used) to grow into two distinct uteri, each with a well-constructed orifice and passage, and each furnished with numerous muscles, nerves, glands and ves- sels, if they had not formerly passed through a similar course of development, as in the case of existing marsu- pials. No one will pretend that so perfect a structure as tho abnornal double uterus in woman could be the result of mere chance. But the principle of reversion, by which long-lost dormant structures are called back into exist- ence, might serve as the guide for the full develojunent of the organ, even after the lapse of an enormous interval of time. Prof. Canestrini,36 after discussing the foregoing and various analogous cases, arrives at the same conclusion as that just given. He adduces, as another instance, the malar bone, which, in some of the Quadrumana and other mammals, normally consists of two portions. This is its condition in the two-months-old human foetus ; and thus it sometimes remains, through arrested development, in man when adult, more especially in the lower prognathous races. Hence Canestrini concludes that some ancient 35 See Dr. A. Farre's well-known article in the l Cyclop, of Anat. and Phys.' vol. v. 1859, p. 642. Owen, 'Anatomy of Vertebrates,' vol. iii. 1868, p. 687. Prof. Turner in 'Edinburgh Medical Journal,' Feb. 1865. 36 ' Annuario della Soc. dei Naturalisti in Modena,' 1867, p. 83. Prof. Canestrini gives extracts en this subject from various authorities. Lau- tillard remarks that, as he has found a complete similarity in the form, proportions, and connection of the two malar bones in several human subjects and in certain apes, he cannot consider this disposition of the parts as simply accidental. 120 THE DESCENT OF MAN. [Part I. progenitor of man must have possessed this bone nor- mally divided into two portions, which subsequently be- came fused together. In man the frontal bone consists of a single piece, but in the embryo and in children, and in almost all the lower mammals, it consists of two pieces sepa- rated by a distinct suture. This suture occasionally per- sists, more or less distinctly, in man after maturity, and more frequently in ancient than in recent crania, especially as Canestrini has observed in those exhumed from the Drift and belonging to the brachycephalic type. Here again he comes to the same conclusion as in the analogous case of the malar bones. In this and other instances presently to be given, the cause of ancient races approaching the lower animals in certain characters more frequently than do the modern races, appears to be that the latter stand at a somewhat greater distance in the long line of descent from their early semi-human progenitors. Various other anomalies in man, more or less anal- ogous with the foregoing, have been advanced by dif- ferent authors 37 as cases of reversion ; but these seem not a little doubtful, for we have to descend extremely low in the mammalian series before we find such structures nor- mally present.38 37 A whole series of cases is given by Isid. Geoffroy St.-Hilaire, 1 Hist, des Anomalies,' torn. iii. p. 437. 38 In my ' Variation of Animals under Domestication ' (vol. ii. p. 57) I attributed the not very rare cases of supernumerary mammas in women to reversion. I was led to this as a probable conclusion, by the additional mammae being generally placed symmetrically on the breast, and more especially from one case, in which a single efficient mamma occurred in the inguinal region of a woman, the daughter of another woman with supernumerary mammae. But Prof. Preyer (' Der Kampf um das Dasein,' 1869, s. 45) states that mammce erraticce have been known to occur iu other situations, even on the back ; so that the force of my argument is greatly weakened or perhaps quite destroyed. With much hesitation I, in the same work (vol. ii., p. 12), attributed the frequent cases of polydactylism in men to reversion. I was partly led Chap. IV.] MANNER OF DEVELOPMENT. 121 In man the canine teeth are perfectly efficient instru- ments for mastication. But their true canine character, as Owen39 remarks, "is indicated by the conical form of the crown, which terminates in an obtuse point, is convex out- ward and flat or subconcave within, at the base of which surface there is a feeble prominence. The conical form is best expressed in the Melanian races, especially the Australian. The canine is more deeply implanted, and by a stronger fang, than the incisors." Nevertheless this tooth no longer serves man as a special weapon for tearing his enemies or prey; it may, therefore, as far as its proper function is concerned, be considered as rudimentary. In every large collection of human skulls some may be found, as Hackel40 observes, with the canine teeth projecting considerably beyond the others in the same manner, but in a less degree, as in the anthropomorphous apes. In these cases, open spaces between the teeth in the one jaw are left for the reception of the canines belonging to the opposite jaw. An interspace of this kind in a Kaffir skull, to this through Prof. Owen's statement, that some of the Ichtbyopterygia possess more than five digits, and therefore, as I supposed, had retained a primordial condition; but after reading Prof. Gegenbaur's paper (' Jenaischen Zeitschrift,' B. v. Heft 3, s. 341), who is the highest author- ity in Europe on such a point, and who disputes Owen's conclusion, I see that it is extremely doubtful whether supernumerary digits can thus be accounted for. It was the fact that such digits not only frequently occur and are strongly inherited, but have the power of regrowth after amputa- tion, like the normal digits of the lower vertebrata, that chiefly led me to the above conclusion. This extraordinary fact of their regrowth remains inexplicable, if the belief in reversion to some extremely remote pro- genitor must be rejected. I cannot, however, follow Prof. Gegenbaur in supposing that additional digits could not reappear through reversion, without at the same time other parts of the skeleton being simultaneous- .y and similarly modified ; for single characters often reappear through reversion. 39 'Anatomy of .Vertebrates,' vol. iii. 1868, p. 323. 40 'Generelle Morphologie,' 1806, B. ii. s. civ. 122 THE DESCENT OF MAN. [Part I. figured by "Wagner, is surprisingly wide.41 Considering bow few ancient skulls have been examined in comparison with recent skulls, it is an interesting fact that in at least three cases the canines project largely ; and in the Nau- lette jaw they are spoken of as enormous.42 The males alone of the anthropomorphous apes have their canines fully developed ; but in the female gorilla, and in a less degree in the female orang, these teeth pro- ject considerably beyond the others ; therefore the fact that women sometimes have, as I have been assured, con- siderably projecting canines, is no serious objection to the belief that their occasional great development in man is a case of reversion to an ape-like progenitor. He who rejects with scorn the belief that the shape of his own canines, and their occasional great development in other men, are due to our early progenitors having been provided with these formidable weapons, will probably reveal by sneer- ing the line of his descent. For, though he no longer in- tends, nor has the power, to use these teeth as weapons, he will unconsciously retract his "snarling muscles" (thus named by Sir C. Bell)43 so as to expose them ready for action, like a dog prepared to fight. Many muscles are occasionally developed in man, which are proper to the Quadrumana or other mammals. Professor Vlacovich44 examined forty male subjects, and found a muscle, called by him the ischiopubic, in nineteen of them; in three others there was a ligament which represented this muscle; and in the remaining eighteen no trace of it. Out of thirty female subjects this muscle was developed on both sides in only two, but in three 41 Carl Vogt's 'Lectures on Man,' Eng. translat. 1864, p. 151. 42 C. Carter Blake, on a jaw from La Naulette, ' Anthropolog. Review, 1867, p. 295. Schaaffhausen, ibid. 1868, p. 426. 43 'The Anatomy of Expression,' 1844, pp. 110, 131. 44 Quoted by Prof. Canestrini in the ' Annuario,' etc., 1867, p. 90. Chap. IV.J MANNER OF DEVELOPMENT. 123 others the rudimentary ligament was present. This muscle, therefore, appears to be much more common in the male than in the female sex ; and on the principle of the descent of man from some lower form, its presence can be understood ; for, it has been detected in several of the lower animals, and in all of these it serves exclusively to aid the male in the act of reproduction. Mr. J. Wood, in his valuable series of papers,45 lias minutely described a vast number of muscular variations in man, which resemble normal structures in the lower animals. Looking only to the muscles which closely re- semble those regularly present in our nearest allies, the Quadrumana, they are too numerous to be here even specified. In a single male subject, having a strong bodily frame and well-formed skull, no less than seven muscular variations were observed, all of which plainly represented muscles proper to various kinds of apes. This man, for instance, had on both sides of his neck a true and power- ful " levator claviculce" such as is found in all kinds of apes, and which is said to occur in about one out of sixty human subjects.46 Again, this man had "a special ab- ductor of the metatarsal bone of the fifth, digit, such as Prof. Huxley and Mr. Flower have shown to exist uniformly in the higher and lower apes." The hands and 45 These papers deserve careful study by any one who desires to learn how frequently our muscles vary, and in varying come to resemble those of the Quadrumana. The following references relate to the few points touched on in my text, 'Proc. Royal Soc' vol. xiv. 18G5, pp. 3'79-3S4; vol. xv. 1866, pp. 241, 242 ; vol. xv. 1867, p. 544; vol. xvi. 1868, p. 524. I may here add that Dr. Murie and Mr. St. George Mivart have shown in their Memoir on the Lemuroidea (Transact: Zoolog. Soc.' vol. vii. 1369, p. 96), how extraordinarily variable some of the muscles are in these ani- mals, the lowest members of the Primates. Gradations, also, in the mus- cles leading to structures found in amimals still lower in the scale, aro numerous in the Lemuroidea. 46 Prof. Macalister in ' Proc. K. Irish Academy,' vul. x. 1868, p. 124. 124 THE DESCENT OF MAN. [Part I. arms of man are eminently characteristic structures, "but their muscles are extremely liable to vary, so as to re- semble the corresponding muscles in the lower animals.47 Such resemblances are either complete and perfect or im- perfect, yet in this latter case manifestly of a transitional nature. Certain variations are more common in man, and others in woman, without our being able to assign any reason. Mr. Wood, after describing numerous cases, makes the following pregnant remark : " Notable depart- ures from the ordinary type of the muscular structures run in grooves or directions, which must be taken to in- dicate some unknown factor, of much importance to a com- prehensive knowledge of general and scientific anatomy." 48 That this unknown factor is reversion to a former state of existence may be admitted as in the highest de- gree probable. It is quite incredible that a man should through mere accident abnormally resemble, in no less than seven of his muscles, certain apes, if there had been no genetic connection between them. On the other hand, if man is descended from some ape-like creature, no valid reason can be assigned why certain muscles should not 47 Prof. Macalister (ibid. p. 121) has tabulated his observations, and finds that muscular abnormalities are most frequent in the forearms, secondly in the face, thirdly in the foot, etc. 48 The Rev. Dr. Haughton, after giving (' Proc. R. Irish Academy,' June 27, 1864, p. 1 15) a remarkable case of variation in the human flexor pollicis longus, adds: "This remarkable example shows that man may sometimes possess the arrangement of tendons of thumb and fingers characteristic of the macaque ; but whether such a case should be re- garded as a macaque passing upward into a man, or a man passing downward into a macaque, or as a congenital freak of Nature, I cannot undertake to say." It is satisfactory to hear so capable an anatomist, and so embittered an opponent of evolutionism, admitting even the pos- sibility of either of his first propositions. Prof. Macalister has also de- scribed ('Proc. R. Irish Acad.' vol. x. 1864, p. 138) variations in the flexor pollicis longus, remarkable from their relations to the same muscle in the Quadrumana. Chap. IV.] MANNER OF DEVELOPMENT. 125 suddenly reappear after an interval of many thousand generations, in the same manner as with horses, asses, and mules, dark-colored -stripes suddenly reappear on the legs and shoulders, after an interval of hundreds, or more prob- ably thousands, of generations. These various cases of reversion are so closely related to those of rudimentary organs given in the first chapter, that many of them might have been indifferently intro- duced in either chapter. Thus a human uterus furnished with cornua may be said to represent in a rudimentary condition the same organ in its normal state in certain mammals. Some parts which are rudimental in man, as the os coccyx in both sexes and the mammae in the male sex, are always present ; while others, such as the supra- condyloid foramen, only occasionally appear, and there- fore might have been introduced under the head of rever- sion. These several reversionary, as well as the strictly rudimentary, structures reveal the descent of man from some lower form in an unmistakable manner. Correlated Variation. — In man, as in the lower ani- mals, many structures are so intimately related, that when one part varies so does another, without our being able, in most cases, to assign any reason. We cannot say whether the one part governs the other, or whether both are governed by some earlier developed part. Various monstrosities, as I. Geoffroy repeatedly insists, are thus intimately connected. Homologous structures are par- ticularly liable to change together, as we see on the op- posite sides of the body, and in the upper and lower ex- tremities. Meckel Ions; ago remarked that when the muscles of the arm depart from their proper type, they almost always imitate those of the leg ; and so conversely with the muscles of the legs. The organs of sight and hearing, the teeth and hair, the color of the skin and 126 THE DESCENT OF MAN. [Part 1 hair, color and constitution, are more or less correlated." Prof. Schaaffkausen first drew attention to the relation apparently existing between a muscular frame and strong- ly-pronounced supra-orbital ridges, which are so char- acteristic of the lower races of man. Besides the variations which can be grouped with more or less probability under the foregoing heads, there is a large class of variations which may be provisionally called spontaneous, for they appear, owing to our igno- rance, to arise without any exciting cause. It can, how- ever, be shown that such variations, whether consisting of slight individual differences, or of strongly-marked and abrupt deviations of structure, depend much more on the constitution of the organism than on the nature of the conditions to which it has been subjected. B0 Hate of Increase. — Civilized populations have been known under favorable conditions, as in the United States, to double their number in twenty-five years; and, ac- cording to a calculation by Euler, this might occur in a little over twelve years." At the former rate the present population of the United States, namely, thirty millions, would in 657 years cover the whole terraqueous globe so thickly, that four men would have to stand on each square yard of surface. The primary or fundamental check to the continued increase of man is the difficulty of gaming subsistence and of living in comfort. We may infer that this is the case from what we see, for instance, in the United States, where subsistence is easy and there is 43 The authorities for these several statements are given in my 1 Variation of Animals under Domestication,' vol. ii. pp. 320-335. 50 This whole subject has been discussed in chap, xxiii. vol. ii. of my 1 Variation of Animals and Plants under Domestication.' 51 See the ever-memorable ' Essay on the Principle of Population/ by the Rev. T. Malthus, vol. i. 1826, pp. 6, 517. Chap. IV.] MANNER OF DEVELOPMENT. 127 plenty of room. If such means were suddenly doubled in Great Britain, our number would be quickly doubled. "With civilized nations the above primary check acts chiefly by restraining marriages. The greater death-rate of infants in the poorest classes is also very important ; as well as the greater mortality at all ages, and from various diseases, of the inhabitants of crowded and mis- erable houses. The effects of severe epidemics and wars are soon counterbalanced, and more than counterbalanced, in nations placed under favorable conditions. Emigration also comes in aid as a temporary check, but not to any great extent with the extremely poor classes. There is reason to suspect, as Malthus has remarked, that the reproductive power is actually less in barbarous than in civilized races. We know nothing positively on this head, for with savages no census has been taken; but from the concurrent testimony of missionaries, and of others who have long resided with such people, it ap- pears that their families are usually small, and large ones rare. This may be partly accounted for, as it is believed, by the women suckling their infants for a* prolonged period ; but it is highly probable that savages, who often suffer much hardship, and who do not obtain so much nu- tritious food as civilized men, would be actually less pro- lific. I have shown in a former work, E2 that all our do- mesticated quadrupeds and birds, and all our cultivated plants, are more fertile than the corresponding species in a state of nature. It is no valid objection to this con- clusion that animals suddenly supplied with an excess of food, or when rendered very fat, and that most plants when suddenly removed from very poor to very rich soil, are rendered more or less sterile. We might, therefore, expect that civilized men, who in one sense are highly do- 59 ' Variation of Animals and Plants under Domestication,' vol. ii. pp, 111-113, 163. 128 THE DESCENT OF MAN. [Part T. mesticated, would be more prolific than wild men. It is also probable that the increased fertility of civilized na- tions would become, as with our domestic animals, an in- herited character : it is at least known that with mankind a tendency to produce twins runs in families.53 Notwithstanding that savages appear to be less pro- lific than civilized people, they would no doubt rapidly in- crease if their numbers were not by some means rigidly kept down. The Santali, or hill-tribes of India, have recently afforded a good illustration of this fact ; for they have increased, as shown by Mr. Hunter,54 at an extraor- dinary rate since vaccination has been introduced, other pestilences mitigated, and war sternly repressed. This increase, however, would not have been possible had not these rude people spread into the adjoining districts and worked for hire. Savages almost always marry; yet there is some prudential restraint, for they do not com- monly marry at the earliest possible age. The young men are often required to show that they can support a wife, and they generally have first to earn the price with which to purchase her from her parents. With savages the difficulty of obtaining subsistence occasionally limits their number in a much more direct manner than with civilized people, for all tribes periodically suffer from se- vere famines. At such times savages are forced to devour much bad food, and their health can hardly fail to be in- jured. Many accounts have been published of their pro- truding stomachs and emaciated limbs after and during famines. They are then, also, compelled to wander much about, and their infants, as I was assured in Australia, perish in large numbers. As famines are periodical, de- pending chiefly on extreme seasons, all tribes must fluc- e3 Mr. Sedgwick, 'British and Foreign Medico-Chirurg. Review,' July, 1663, p. 110. 6* « The Annals of Rural Bengal,' by W. W. Hunter, 1 868, p. 259. Chap. IV.] . MANNER OF DEVELOPMENT. 129 tuate in number. They cannot steadily and regalarly in- crease, as there is no artificial increase in the supply of food. Savages when hardly pressed encroach on each other's territories, and war is the result ; but they are in- deed almost always at war with their neighbors. They are liable to many accidents on land and water in their search for food ; and in some countries they must suffer much from the larger beasts of prey. Even in India, dis- tricts have been depopulated by the ravages of tigers. Malthus has discussed these several checks, but he does not lay stress enough on what is probably the most important of all, namely infanticide, especially of female infants, and the habit of procuring abortion. These prac- tices now prevail in many quarters of the world, and in- fanticide seems formerly to have prevailed, as Mr. M'Len- nan 55 has shown, on a still more extensive scale. These practices appear to have originated in savages recognizing the difficulty, or rather the impossibility, of supporting all the infants that are born. Licentiousness may also be added to the foregoing checks ; but this does not follow from failing means of subsistence ; though there is reason to believe that in some cases (as in Japan) it has been in- tentionally encouraged as a means of keeping down the population. If we look back to an extremely remote epoch, before man had arrived at the dignity of manhood, he would have been guided more by instinct and less by reason than are savages at the present time. Our early semi- human progenitors would not have practised infanticide, for the instincts of the lower animals are never so per- verted as to lead them regularly to destroy their own off- spring. There would have been no prudential restraint from marriage, and the sexes would have freely united at an early age. Hence the progenitors of man would have 66 'Primitive Marriage,' 1865. 130 THE DESCENT OF MAN. . [Part L tended to increase rapidly, but checks of some kind, either periodical or constant, must have kept down their num- bers, even more severely than with existing savages. What the precise nature of these checks may have been, we cannot say, any more than with most other animals. We know that horses and cattle, which are not highly prolific animals, when first turned loose in South America, increased at an enormous rate. The slowest breeder of all known animals, namely the elephant, would in a few thousand years stock the whole world. The increase of every species of monkey must be checked by some means ; but not, as Brehm remarks, by the attacks of beasts of prey. No one will assume that the actual power of re- production in the wild horses and cattle of America was at first in any sensible degree increased ; or that, as each district became fully stocked, this same power was dimin- ished. No doubt in this case, and in all others, many checks concur, and different checks under different circum- stances ; periodical dearths, depending on unfavorable seasons, being probably the most important of all. So it will have been with the early progenitors of man. Natural Selection. — We have now seen that man is variable in body and mind ; and that the variations are induced, either directly or indirectly, by the same general causes, and obey the same general laws, as with the lower animals. Man has spread widely over the face of the earth, and must have been exposed, during his incessant migrations,56 to the most diversified conditions. The in- habitants of Tierra del Fuego, the Caj:>e of Good Hope, and Tasmania in the one hemisphere, and of the Arctic regions in the other, must have passed through many cli- mates and changed their habits many times, before they 58 See some good remains to this effect by W. Stanley Jevons, " A Deduction from Darwin's Theory," 'Nature,' 1869, p. 231. Cijap. IV.] MANNER OF DEVELOPMENT. 131 reached their present homes." The early progenitors of man must also have tended, like all other animals, to have increased beyond their means of subsistence ; they must therefore occasionally have been exposed to a struggle for existence, and consequently to the rigid law of natural selection. Beneficial variations of all kinds will thus, either occasionally or habitually, have been preserved, and injurious ones eliminated. I do not refer to strongly- marked deviations of structure, which occur only at long intervals of time, but to mere individual differences. We know, for instance, that the muscles of our hands and feet, which determine our powers of movement, are liable, like those of the lower animals,68 to incessant variability. If, then, the ape-like progenitors of man which inhabited any district, especially one undergoing some change in its con- ditions, were divided into two equal bodies, the one half which included all the individuals best adapted by their powers of movement for gaining subsistence or for defend- ing themselves, would on an average survive in greater number and procreate more offspring than the other and less well-endowed half. Man in the rudest state in which he now exists is the most dominant animal that has ever appeared on the earth. He has spread more widely than any other highly-organ- ized form ; and all others have yielded before him. He manifestly owes this immense superiority to his intellectual faculties, his social habits, which lead him to aid and de- fend his fellows, and to his corporeal structure. The supreme importance of these characters has been proved 67 Latham, 'Man and his Migrations,' 1S51, p. 135. 6S Messrs. Murie and Mivart, in their " Anatomy of the Lemuroidea " (' Transact. Zoolog. Soc.' vol. vii. 1869, pp. 96-98) say, " some muscles are go irregular in their distribution that they cannot be well classed in any of the above groups." These muscles differ even on the opposite sides of the same individual. 132 THE DESCENT OF MAN. [Part T. by the final arbitrament of the battle for life. Through his powers of intellect, articulate language has been evolved; and on this his wonderful advancement has mainly depended. He has invented and is able to use various weapons, tools, traps, etc., with which he defends himself, kills or catches prey, and otherwise obtains food. He has made rafts or canoes on which to fish or cross over to neighboring fertile islands. He has discovered the art of making fire, by which hard and stringy roots can be rendered digestible, and poisonous roots or herbs innocu- ous. This last discovery, probably the greatest, excepting language, ever made by man, dates from before the dawn of history. These several inventions, by which man in the rudest state has become so preeminent, are the direct re- sult of the development of his powers of observation, memory, curiosity, imagination, and reason. I cannot, therefore, understand how it is that Mr. "Wallace B9 main- tains, that "natural selection could only have endowed the savage with a brain a little superior to that of an ape." Although the intellectual powers and social habits of 59 'Quarterly Review,' April, 1869, p. 392. This subject is more fully discussed in Mr. Wallace's ' Contributions to the Theory of Natural Selection,' 1870, in which all the essays referred to in this work are re- published. The ' Essay on Man ' has been ably criticised by Prof. Clapa- rede, one of the most distinguished zoologists in Europe, in an article published in the ' Bibliotheque Universelle,' June, 1870. The remark quoted in my text will surprise every one who has read Mr. Wallace's celebrated paper on ' The Origin of Human Races deduced from the Theory of Natural Selection,' originally published in the ' Anthropologi- cal Review,' May, 1864, p. clviii. I cannot here resist quoting a most just remark by Sir J. Lubbock (' Prehistoric Times,' 1865, p. 479) in reference to this paper, namely, that Mr. Wallace, " with characteristic unselfishness, ascribes it (i e., the idea of natural selection) unreservedly to Mr. Darwin, although, as is well known, he struck out the idea inde- pendently, and published it, though not with the same elaboration, at the same time." Chap. IV.] MANNER OF DEVELOPMENT. 133 man are of paramount importance to him, we must not underrate the importance of his bodily structure, to which subject the remainder of this chajfter will be devoted. The development of the intellectual and social or moral faculties will be discussed in the following chapter. Even to hammer with precision is no easy matter, as every one who has tried to learn carpentry will admit. To throw a stone with as true an aim as can a Fuegian in defending himself, or in killing birds, requires the most consummate perfection in the correlated action of the muscles of the hand, arm, and shoulder, not to mention a fine sense of touch. In throwing a stone or spear, and in many other actions, a man must stand firmly on his feet ; and this again demands the perfect coadaptation of nu- merous muscles. To chip a flint into the rudest tool, or to form a barbed spear or hook from a bone, demands the use of a perfect hand ; for, as a most capable judge, Mr. Schoolcraft,60 remarks, the shaping fragments of stone into knives, lances, or arrow-heads, shows " extraordinary abil- ity and long practice." We have evidence of this in primeval men having practised a division of labor ; each man did not manufacture his own flint tools or rude pot- tery ; but certain individuals appear to have devoted themselves to such work, no doubt receiving in exchange the produce of the chase. Archaeologists are convinced that an enormous interval of time elapsed before our an- cestors thought of grinding chipped flints into smooth tools. A man-like animal who possessed a hand and arm sufficiently perfect to throw a stone with precision or to form a flint into a rude tool, could, it can hardly be doubt- ed, with sufficient practice make almost any thing, as far as mechanical skill alone is concerned, which a civilized 60 Quoted by Mr. Lawson Tait in his " Law of Natural Selection " — Dublin Quarterly Journal of Medical Science/ Feb. 1869. Dr. Keller is likewise quoted to the same effect. 134 THE DESCENT OF MAN. [Part I. man can make. The structure of the hand in this respect may be compared with that of the vocal organs, which in the apes are used for -uttering various signal-cries, or, as in one species, musical cadences ; hut in man closely similar vocal organs have become adapted through the inherited effects of use for the utterance of articulate language. Turning now to the nearest allies of man, and there- fore to the best representatives of our early progenitors, we find that the hands in the Quadrumana are constructed on the same general pattern as in us, but are far less per- fectly adapted for diversified uses. Their hands do not serve so well as the feet of a dog for locomotion ; as may be seen in those monkeys which walk on the outer mar- gins of the palms, or on the backs of their bent fingers, as in the chimpanzee and orang.61 Their hands, however, are admirably adapted for climbing trees. Monkeys seize thin branches or ropes, with the thumb on one side and the fingers and palm on the other side, in the same manner as we do. They can thus also carry rather large objects, such as the neck of a bottle, to their mouths. Baboons turn over stones and scratch up roots with their hands. They seize nuts, insects, or other small objects, with the thumb in opposition to the fingers, and no doubt they thus extract eggs and the young from the nests of birds. American monkeys beat the wild oranges on the branches until the rind is cracked, and then tear it off with the fin- gers of the two hands. Other monkeys open mussel-shells with the two thumbs. With their fingers they pull out thorns and burs, and hunt for each other's parasites. In a state of Nature they break open hard fruits with the aid of stones. They roll down stones or throw them at their enemies ; nevertheless, they perform these various actions clumsily, and they are quite unable, as I have myself seen, to throw a stone with precision. 61 Owen, 'Anatomy of Vertebrates.' vol. iii. p. *71. Chap. IV.] MASKER OF DEVELOPMENT. 135 It seems to me far from true that because " objects are grasped clumsily " by monkeys, " a much less specialized organ of prehension " would have served them 62 as well as their present hands. On the contrary, I see no reason to doubt that a more perfectly constructed hand would have been an advantage to them, provided, and it is im- portant to note this, that their hands had not thus been rendered less well adapted for climbing trees. We may suspect that a perfect hand would have been disadvanta- geous for climbing ; as the most arboreal monkeys in the world, namely Ateles in America and Hylobates in Asia, either have their thumbs much reduced in size and even rudimentary, or their fingers partially coherent, so that their hands are converted into mere grasping- hooks.63 As soon as some ancient member in the great series of the Primates came, owing to a change in its manner of procuring subsistence, or to a change in the conditions of its native country, to live somewhat less on trees and more on the ground, its manner of progression would have been modified ; and in this case it would have had to be- come either more strictly quadrupedal or bipedal. Ba- boons frequent hilly and rocky districts, and only from necessity climb up high trees ; G4 and they have acquired almost the gait of a dog. Man alone has become a biped ; and we can, I think, partly see how he has come to assume his erect attitude, which forms one of the most conspicu- ous differences between him and his nearest allies. Man could not have attained his present dominant position in the world without the use of his hands, which are so ad- 62 'Quarterly Review,' April, 18G9, p. 392. 63 In Hylobates syndactylies, as the name expresses, two of the digits regularly cohere ; and this, as Mr. Blyth informs me, is occasionally the case with the digits of //. agilis, lar, and leuciscus. •4 Brehm, ■ Thierleben,' B. i. s. 80. 136 THE DESCENT OF MAN. [Part L mirably adapted to act in obedience to his will. As Sir C. Bell 66 insists, " the hand supplies all instruments, and by its correspondence with the intellect gives him univer- sal dominion." But the hands and arms could hardly have become perfect enough to have manufactured weap- ons, or to have hurled stones and spears with a true aim, as long as they were habitually used for locomotion and for supporting the whole weight of the body, or as long as they were especially well adapted, as previously remarked, for climbing trees. Such rough treatment would also have blunted the sense of touch, on which their delicate use largely depends. From these causes alone it would have been an advantage to man to have become a biped ; but for many actions it is almost necessary that both arms and the whole upper part of the body should be free ; and he must for this end stand firmly on his feet. To gain this great advantage, the feet have been rendered flat, and the great-toe peculiarly modified, though this has entailed the loss of the power of prehension. It accords with the prin- ciple of the division of physiological labor, which prevails throughout the animal kingdom, that, as the hands became perfected for prehension, the feet should have become per- fected for support and locomotion. With some savages, however, the foot has not altogether lost its prehensile power, as shown by their manner of climbing trees and of using them in other ways.66 If it be an advantage to man to have his hands and 65 "The Hand, its Mechanism," etc. 'Bridgewater Treatise,' 1833, p. 38. 66 Hackel has an excellent discussion on the steps by which man be- came a biped: 'Natiirliche Schopfungsgeschichte,' 1868, s. 507. Dr. Biichner ('Conferences sur la Theorie Darwinienne,' 1869, p. 135) has given good cases of the use of the foot as a prehensile organ by man ; also on the manner of progression of the higher apes to which I allude in the following paragraph : see also Owen ('Anatomy of Vertebrates,' vol. Hi. p. 71) on this latter subject. Chap. IV.] MANNER OF DEVELOPMENT. 13 h arms free and to stand firmly on his feet, of which there can be no doubt from his preeminent success in the battle of life, then I can see no reason why it should not have been advantageous to the progenitors of man to have be- come more and more erect or bipedal. They would thus have been better able to have defended themselves with stones or clubs, or to have attacked their prey, or other- wise obtained food. The best-constructed individuals would in the long-run have succeeded best, and have sur- vived in larger numbers. If the gorilla and a few allied forms had become extinct, it might have been argued with great force and apparent truth, that an animal could not have been gradually converted from a quadruped into a biped ; as all the individuals in an intermediate condition would have been miserably ill-fitted for progression. But we know (and this is well worthy of reflection) that sev- eral kinds of apes are now actually in this intermediate condition ; and no one doubts that they are on the whole well adapted for their conditions of life. Thus the gorilla runs with a sidelong shambling gait, but more commonly progresses by resting on its bent hands. The long-armed apes occasionally use their arms like crutches, swinging their bodies forward between them, and some kinds of Hylobates, without having been taught, can walk or run upright with tolerable quickness ; yet they move awk- wardly, and much less securely than man. We see, in short, with existing monkeys various gradations between a form of progression strictly like that of a quadruped and that of a biped or man. As the progenitors of man became more and more erect, with their hands and arms more and more modified for prehension and other purposes, with their feet and legs at the same time modified for firm support and progres- sion, endless other changes of structure would have been necessary. The pelvis would have had to be made broader, 138 THE DESCENT OF MAN. [Pakt I. the spine peculiarly curved and the head fixed in an altered position, and all these changes have been attained by man. Prof. Schaafthausen67 maintains that "the powerful mastoid processes of the human skull are the result of his erect position;" and these processes are absent in the orang, chimpanzee, etc., and are smaller in the gorilla than in man. Various other structures might here have been specified, which appear connected with man's erect posi- tion. It is very difficult to decide how far all these cor- related modifications are the result of natural selection, and how far of the inherited effects of the increased use of certain parts, or of the action of one part on another. No doubt these means of change act and react on each other : thus when certain muscles, and the crests of bone to which they are attached, become enlarged by habitual use, this shows that certain actions are habitually performed and must be serviceable. Hence the individuals which per- formed them best, would tend to survive in greater num- bers. The free use of the arms and hands, partly the cause and partly the result of man's erect position, appears to have led in an indirect manner to other modifications of structure. The early male progenitors of man were, as previously stated, probably furnished with great canine teeth ; but as they gradually acquired the habit of using stones, clubs, or other weapons, for fighting with their enemies, they would have used their jaws and teeth less and less. In this case, the jaws, together with the teeth, would have become reduced in size, as we may feel sure from innumerable analogous cases. In a future chapter we shall meet with a closely-parallel case, in the reduction or complete disappearance of the canine teeth in male rumi- 67 " On the Primitive Form of the Skull," translated in ' Anthropo- logical Review,' Oct. 18G8, p. 428. Owen (' Anatomy of Vertebrates,' rol. ii. 18G6, p. 551) on the mastoid processes in the higher apes. Chap. IV.] MANNER OF DEVELOPMENT. 139 nants, apparently in relation with the development of their horns ; and in horses, in relation with their habit of fighting with their incisor teeth and hoofs. In the adult male anthropomorphous apes, as Rtiti- meyer,68 and others have insisted, it is precisely the effect which the jaw-muscles by their great development have produced on the skull, that causes it to differ so greatly in many respects from that of man, and has given to it " a truly frightful physiognomy." Therefore, as the jaws and teeth in the progenitors of man gradually become reduced in size, the adult skull would have presented nearly the same characters which it offers in the young of the an- thropomorphous apes, and would thus have come to resemble more nearly that of existing man. A great re- duction of the canine teeth in the males would almost cer- tainly, as we shall hereafter see, have affected through inheritance the teeth of the females. As the various mental faculties have gradually de- veloped, the brain would almost certainly have become larger. No one, I presume, doubts that the large size of the brain in man, relatively to his body, in comparison to that of the gorilla or orang, is closely connected with his higher mental powers. We meet with closely-analogous facts with insects, in which the cerebral ganglia are of extraordinary dimensions in ants ; these ganglia in all the Hymenoptera being many times larger than in the less in- telligent orders, such as beetles.69 On the other hand, no one supposes that the intellect of any two animals, or of any two men, can be accurately gauged by the cubic con- 68 ' Die Grenzen der Thierwelt, erne Betrachtung zu Darwin's Lehre,' 1868, s. 51. 69 Dujardin, ' Annales dcs Sc. Nat.' 3d series, Zoolog. torn. xiv. 1850, p. 203. See also Mr. Lowne, ' Anatomy and Phys. of the Musca vomito- Wa,' 18*70, p. 14. My son, Mr. F. Darwin, dissected for me the cerebral ganglia of the Formica rufa. 140 THE DESCENT OF MAN. [Part L tents of their skulls. It is certain that there may be extraor- dinary mental activity with an extremely small absolute mass of nervous matter; thus the wonderfully diversified instincts, mental powers, and affections of ants, are gen- erally known, yet their cerebral ganglia are not so large as the quarter of a small pin's head. Under this latter point of view, the brain of an ant is one of the most mar- vellous atoms of matter in the world, perhaps more mar- vellous than the brain of man. The belief that there exists in man some close relation between the size of the brain and the development of the intellectual faculties is supported by the comparison of the skulls of savage and civilized races, of ancient and modern people, and by the analogy of the whole vertebrate series. Dr. J. Barnard Davis has proved 70 by many careful meas- urements, that the mean internal capacity of the skull in Europeans is 92.3 cubic inches; in Americans 87.5; in Asiatics 87.1 ; and in Australians only 81.9 inches. Prof. Broca71 found that skulls from graves in Paris of the nineteenth century, were larger than those from vaults of the twelfth century, in the proportion of 1484 to 1426; and Prichard is persuaded that the present inhabitants of Britain have "much more capacious brain-cases" than the ancient inhabitants. Nevertheless it must be admitted that some skulls of very high antiquity, such as the famous one of Neanderthal, are well developed and capacious. With respect to the lower animals, M. E. Lartet,72 by comparing the crania of tertiary and recent mammals, be- longing to the same groups, has come to the remarkable conclusion that the brain is generally larger and the con- volutions more complex in the more recent form. On the 10 'Philosophical Transactions,' 18G9, p. 513. 11 Quoted in C. Vogt's 'Lectures on Man,' Eng. translat. 1864, pp. 88, 90. Prichard, 'Phys. Hist, of Mankind,' vol. i. 1838, p. 305 w ' Cjpmptes Rendus des Seances,' etc., June 1, 1868. Chap. IV.] MANNER OF DEVELOPMENT. 141 other hand, I have shown73 that the brains of domestic rabbits are considerably reduced in bulk, in comparison with those of the wild rabbit, or hare ; and this may be attributed to their having been closely confined during many generations, so that they have exerted but little their intellect, instincts, senses, and voluntary movements. The gradually-increasing weight of the brain and skull in man must have influenced the development of the supporting spinal column, more especially while he was becoming erect. As this change of position was being brought about, the internal pressure of the brain will, also, have influenced the form of the skull ; for many facts show how easily the skull is thus affected. Ethnologists believe that it is modified by the kind of cradle in which infants sleep. Habitual spasms of the muscles and a cic- atrix from a severe burn have permanently modified the facial bones. In young persons whose heads from disease have become fixed either sideways or backward, one of the eyes has changed its position, and the bones of the skull have been modified; and this apparently results from the brain pressing in a new direction.74 I have shown that with long-eared rabbits, even so trifling a cause as the lopping forward of one ear drags forward on that side almost every bone of the skull ; so that the bones on the opposite sides no longer strictly correspond. Lastly, if any animal were to increase or diminish much in general size, without any change in its mental powers ; or if the mental 73 c The Variation of Animals and Plants under Domestication,' vol. i. pp. 124-129. 71 Schaaffhausen gives from Blumenbach and Busch, the cases of the spasms and cicatrix, in ' Anthropolog. Review,' Oct. 1868, p. 420. Dr. Jarrold (' Anthropologia,' 1808, pp. 115, 11G) adduces from Camper and from hi3 own observations, cases of the modification of the skull from the head being fixed in an unnatural position. He believes that certain trades, such as that of a shoemaker, by causing the head to be habitually held forward, makes the forehead more rounded and prominent. 142 THE DESCENT OF MAN. [P^t I. powers were to be much increased, or diminished, without any great change in the size of the body; the shape of the skull would almost certainly be altered. I infer this from my observations on domestic rabbits, some kinds of which have become very much larger than the wild animal while others have retained nearly the same size, but in both cases the brain has been much reduced rela- tively to the size of the body. Now I was at first much surprised by finding that in all these rabbits the skull had become elongated or dolichocephalic ; for instance, of two skulls of nearly equal breadth, the one from a wild rabbit and the other from a large domestic kind, the former was only 3.15, and the latter 4.3 inches in length.75 One of the most marked distinctions in different races of man is that the skull in some is elongated, and in others rounded ; and here the explanation suggested by the case of the rabbits may partially hold good ; for Welcker finds that " short men incline more to brachycephaly, and tall men to dolichoccphaly ; " " and tall men may be compared with the larger and longer-bodied rabbits, all of which have elongated skulls, or are dolichocephalic. From, these several facts we can to a certain extent understand the means through which the great size and more or less rounded form of the skull has been acquired by man ; and these are characters eminently distinctive of him in comparison with the lower animals. Another most conspicuous difference between man and the lower animals is the nakedness of his skin. Whales and dolphins (Cetacea), dugongs (Sirenia), and the hip- popotamus, are naked ; and this may be advantageous to them for gliding through the water; nor would it be in- 75 'Variation of Animals,' etc., vol. i. p. 117 on the elongation of the 6kull ; p. 119, on the effect of the lopping of one ear. 76 Quoted by Schaaffhausen, in ' Authropolog. Review,' Oct. 18(58> p. 419. Chap. IV.] MANNER OF DEVELOPMENT. 143 jurious to them from the loss of warmth, as the species which inhabit the colder regions are protected by a thick layer of blubber, serving the same purpose as the fur of seals and otters. Elephants and rhinoceroses are almost hairless; and, as certain extinct species which formerly lived under an arctic climate were covered with long wool or hair, it would almost appear as if the existing species of both genera had lost their hairy covering from expos- ure to heat. This appears the more probable, as the elephants in India which live on elevated and cool dis- tricts are more hairy " than those on the lowlands. May we then infer that man became divested of hair from hav- ing aboriginally inhabited some tropical land ? The fact of the hair being chiefly retained in the male sex on the chest and face, and in both sexes at the junction of all four limbs with the trunk, favors this inference, assuming that the hair was lost before man became erect ; for the parts which now retain most hair would then have been most protected from the heat of the sun. The crown of the head, however, offers a curious exception, for at all times it must have been one of the most exposed parts, yet it is thickly clothed with hair. In this respect man agrees with the great majority of quadrupeds, which gen- erally have their upper and exposed surfaces more thickly clothed than the lower surface. Nevertheless, the fact that the other members of the order of Primates, to which man belongs, although inhabiting various hot regions, are well clothed with hair, generally thickest on the upper surface,78 is strongly opposed to the supposition that man became naked through the action, of the sun. I am in- " Owen, 'Anatomy of Vertebrates,' vol. iii. p. G19. 73 Isidore Geoffroy St.-Hilaire remarks ('Hist. Nat. Generale,' torn, ii 1859, pp. 215-21*7) on the head of man being covered with long hair; also on the upper surfaces of monkeys and of other mammals being moro thickly clothed than the lower surfaces. This has likewise been ob- L44 THE DESCENT OF MAN. [Part I. clined to believe, as we shall see under sexual selection, that man, or rather primarily woman, became divested of hair for ornamental purposes ; and according to this belief it is not surprising that man should differ so greatly in hairiness from all his lower brethren, for characters gained through sexual selection often differ in closely-related forms to an extraordinary degree. ' According to a popular impression, the absence of a tail is eminently distinctive of man ; but as those apes which come nearest to man are destitute of this organ, its disappearance does not especially concern us. Never- theless it may be well to own that no explanation, as far as I am aware, has ever been given of the loss of the tail by certain apes and man. Its loss, however, is not sur- prising, for it sometimes differs remarkably in length in species of the same genera : thus in some species of Maca- cus the tail is longer than the whole body, consisting of twenty-four vertebrae ; in others it consists of a scarcely- visible stump, containing only three or four vertebrae. In some kinds of baboons there are twenty-five, while in the mandrill there are ten very small stunted caudal vertebra?, or, according to Cuvier,79 sometimes only five. This great diversity in the structure and length of the tail in animals belonging to the same genera, and following nearly the same habits of life, renders it probable that the tail is not of much importance to them ; and if so, we might have ex- pected that it would sometimes have become more or less rudimentary, in accordance with what we incessantly see served by various authors. Prof. P. Gervais ('Hist. Nat. des Mammi- feres,' torn. i. 1854, p. 28), however, states that in the Gorilla the hair is thinner on the back, where it is partly rubbed off, than on the lower sur- face. 19 Mr. St. George Mivart, ' Proc. Zoolog. Soc.' 18G5, pp. 562, 583. Dr. J. E. Gray, ' Cat. Brit. Mus. : Skeletons.' Owen, ' Anatomy of Verte- brates,' vol. ii. p. 517. Isidore Geoffroy, ' Hist. Nat. Gen.' torn. ii. p. 244. Chap. IV.] MANNER OF DEVELOPMENT. 145 with other structures. The tail almost always tapers toward the end, whether it be long or short ; and this, I presume, results from the atrophy, through disuse, of the terminal muscles, together with their arteries and nerves, leading to the atrophy of the terminal bones. With re- spect to the os coccyx, which in man and the higher apes manifestly consists of the few basal and tapering segments of an ordinary tail, I have heard it asked how could these have become completely embedded within the body ; but there is no difficulty in this respect, for in many monkeys the basal segments of the true tail are thus embedded. For instance, Mr. Murie informs me that in the skeleton ot a not full-grown Macacus inomatus, he counted nine or ten caudal vertebra?, which altogether were only 1.8 inch in length. Of these the three basal ones appeared to have been embedded ; the remainder forming the free part of the tail, which was only one inch in length, and half an inch in diameter. Here, then, the three embedded caudal vertebras plainly correspond with the four coalesced ver- tebrae of the human os coccyx. I have now endeavored to show that some of the most distinctive characters of man have in all probability been acquired, either directly, or more commonly indirectly, through natural selection. We should bear in mind that modifications in structure or constitution, which are of no service to an organism in adapting it to its habits of life, to the food which it consumes, or passively to the sur- rounding conditions, cannot have been thus acquired. We must not, however, be too confident in deciding what modifications are of service to each being : we should re- member how little we know about the use of many parts, or what changes in the blood or tissues may serve to fit an organism for a new climate or some new kind of food. Nor must we forget the principle of correlation, by which, 140 THE DESCENT OF MAN. [Part L as Isidore Geoffroy lias shown in the case of man, many strange deviations of structure are tied together. Inde- pendently of correlation, a change in one part often leads, through the increased or decreased use of other parts, to other changes of a quite unexpected nature. It is also well to reflect on such facts, as the wonderful growth of galls on plants caused by the poison of an insect, and on the remarkable changes of color in the plumage of parrots when fed on certain fishes, or inoculated with the poison of toads ; 80 for we can thus see that the fluids of the system, if altered for some special purpose, might induce other strange changes. We should especially bear in mind that modifications acquired and continually used during past ages for some useful purpose would probably become firmly fixed and might be long inherited. Thus a very large yet undefined extension may safely be given to the direct and indirect results of natural selec- tion ; but I now admit, after reading the essay by Niigeli on plants, and the remarks by various authors with respect to animals, more especially those recently made by Prof. Broca, that in the earlier editions of my l Origin of Spe- cies ' I probably attributed too much to the action of natu- ral selection or the survival of the fittest. I have altered the fifth edition of the Origin so as to confine my remarks to adaptive changes of structure. I had not formerly sufficiently considered the existence of many structures which appear to be, as far as we can judge, neither bene- ficial nor injurious ; and this I believe to be one of the greatest oversights as yet detected in my work. I may be permitted to say, as some excuse, that I had two dis- tinct objects in view, firstly, to show that species had not been separately created, and secondly, that natural selec- tion had been the chief agent of change, though largely 80 'The Variation of Animals and Flants under Domestication,* \ol. it pp. 280, 282. Chap. IV.] MANNER OF DEVELOPMENT. 147 aided by the inherited effects of habit, and slightly by the direct action of the surrounding conditions. Nevertheless I was not able to annul the influence of my former belief, then widely prevalent, that each species had been pur- posely created ; and this led to my tacitly assuming that every detail of structure, excepting rudiments, was of some special, though unrecognized, service. Any one with this assumption in his mind would naturally extend the action of natural selection, either during past or pres- ent times, too far. Some of those who admit the principle of evolution, but reject natural selection, seem to forget, when criticism o* mv book, that I had the above two ob- jects in view ; hence if I have erred in giving to natural selection great power, which I am far from admitting, or in having exaggerated its power, which is in itself prob- able, I have at least, as I hope, done good service in aid- ing to overthrow the dogma of separate creations. That all organic beings, including man, present many modifications of structure which are of no service to them at present, nor have been formerly, is, as I can now see, probable. We know not what produces the numberless slight differences between the individuals of each species, for reversion only carries the problem a few steps back- ward ; but each peculiarity must have had its own efficient cause. If these causes, whatever they may be, were to act Vnore uniformly and energetically during a lengthened period (and no reason can be assigned why this should not sometimes occur), the result would probably be not mere slight individual differences, but well-marked, constant modifications. Modifications which -are in no way bene- ficial cannot have been kept uniform through natural se- lection, though any which were injurious would have been thus eliminated. Uniformity of character would, how- ever, naturally follow from the assumed uniformity of the exciting causes, and likewise from the free intercrossing 148 THE DESCENT OF MAN. [Part I. of many individuals. The same organism might acquire in this manner during successive periods successive modi- fications, and these would be transmitted in a nearly uni- form state as long as the exciting causes remained the same and there was free intercrossing. With respect to the exciting causes we can only say, as when speaking of so-called spontaneous variations, that they relate much more closely to the constitution of the varying organism, than to the nature of the conditions to which it has been subjected. Conclusion. — In this chapter we have seen that as man at the present day is liable, like every other animal, to multiform individual differences or slight variations, so no doubt were the early progenitors of man ; the variations being then as now induced by the same general causes, and governed by the same general and complex laws. As all animals tend to multiply beyond their means of sub- sistence, so it must have been with the progenitors of man ; and this will inevitably have led to a struggle for existence and to natural selection. This latter process will have been greatly aided by the inherited effects of the increased use of parts ; these two processes incessant- ly reacting on each other. It appears, also, as we shall hereafter see, that various itnimportant characters have been acquired by man through sexual selection. An unex- plained residuum of change, perhaps a large one, must be left to the assumed uniform action of those unknown as;en- cies, which occasionally induce strongly-marked and ab- rupt deviations of structure in our domestic productions. Judging from the habits of savages and of the greater number of the Quadrumana, primeval men, and even the ape-like progenitors of man, probably lived in society. With strictly social animals, natural selection sometimes acts indirectly on the individual, through the preservation Chap. IV.] MANNER OF DEVELOPMENT. 149 of variations which are beneficial only to the community. A community including a large number of well-endowed individuals increases in number and is victorious over other and less well-endowed communities ; although each separate member may gain no advantage over the other members of the same community. With associated in- sects many remarkable structures, which are of little or no service to the individual or its own offspring, such as the pollen-collecting apparatus, or the sting of the worker- bee, or the great jaws of soldier-ants, have been thus ac- quired. With the higher social animals, I am not aware that any structure has been modified solely for the good of the community, though some are of secondary service to it. For instance, the horns of ruminants and the great canine teeth of baboons appear to have been acquired by the males as weapons for sexual strife, but they are used in defence of the herd or troop. In regard to certain mental faculties the case, as we shall see in the following chapter, is wholly different ; for these faculties have been chiefly, or even exclusively, gained for the benefit of the community ; the individuals composing the community being at the same time indirectly benefited. It has often been objected to such views as the fore- going, that man is one of the most helpless and defence- less creatures in the world ; and that during his early and less well-developed condition he would have been still more helpless. The Duke of Argyll, for instance, insists 8l that "the human frame has diverged from the structure of brutes, in the direction of greater physical helplessness and weakness. That is to say, it is a divergence which of all others it is most impossible to ascribe to mere natural selection." He adduces the naked and unprotected state 81 'Primeval Man,' 1860, p. 66. 150 THE DESCENT OF MAN. [Part I. of the body, the absence of great teeth or claws for de- fence, the little strength of man, his small speed in run- ning, and his slight power of smell, by which to discover food or to avoid danger. To these deficiencies there mio-ht have been added the still more serious loss of the power of quickly climbing trees, so as to escape from ene- mies. 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 inhabited 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 has become larger and stronger, or smaller and weaker, in comparison with his progenitors. We should, how- ever, 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 failed to become social ; and this would most effectually have checked the acquirement by man of his higher mental qualities, such as sympathy and the love of his fellow-creatures. Hence it might have been an immense advantage to man to have sprung from some comparatively weak creature. The slight corporeal strength of man, his little speed, his want of natural weapons, etc., are more than counter- balanced, firstly by his intellectual powers, through which he has, while still remaining in a barbarous state, formed Chap. I V.J MANNER OF DEVELOPMENT. 151 for himself weapons, tools, etc., 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 dangerous beasts than Southern Africa; no country presents more fearful physical hard- ships than the Arctic regions ; yet one of the puniest races, namely, the Bushmen, maintain themselves in Southern Africa, as do the dwarfed Esquimaux in the Arctic regions. The 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, while they gradually lost their brute-like powers, such as climb- ing trees, etc., they at the same time advanced in intellect. 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 the 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 favorable con- ditions, to have raised man, through the survival of the fittest, combined with the inherited effects of habit, to his present high position in the organic scale. 152 THE DESCENT OF MAN. TPakt I. CHAPTER V. ON THE DEVELOPMENT OF THE INTELLECTUAL AND MORAL FACULTIES DURING PRIMEVAL AND CIVILIZED TIMES. The Advancement of the Intellectual Powers through Natural Selection.— Importance of Imitation. — Social and Moral Faculties. — Their Develop- ment within the Limits of the same Tribe. — Natural Selection as af- fecting Civilized Nations. — Evidence that Civilized Nations were once barbarous. The subjects to be discussed in this chapter are of the highest 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 unchanged body in harmony with the changing universe." He has great power of adapting his habits to new conditions of life. He invents weapons, tools, and various stratagems, by which he procures food and de- fends 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. 1 'Anthropological Review,' May, 1864, p. clviii. Chap. V.] INTELLECTUAL FACULTIES. 153 Even at a remote period he practised some subdivision of labor. The lower animals, on the other hand, must have their bodily structure modified in order to survive under great- ly-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 case, however, is widely different, as Mr. Wallace has with justice insisted, in relation to the intellectual and moral faculties of man. These faculties are variable ; and we have every reason to believe that the variations tend to be inherited. Therefore, if they were formerly of high importance to primeval man and to his ape-like pro- genitors, they would have been perfected or advanced through natural selection. Of the high importance of the intellectual faculties there can be no doubt, for man main- ly owes to them his preeminent position in the world. We can see that, in the rudest state of society, the indi- viduals who were the most sagacious, who invented and used the best weapons or traps, and who were best able to defend themselves, would rear the greatest number of offspring. The tribes which included the largest number of men thus endowed would increase in number and sup- plant other tribes. Numbers depend primarily on the means of subsistence, and this, partly on the physical nature of the country, but in a much higher degree on the arts which are there practised. As a tribe increases and is victorious, it is often still further increased by the ab- sorption of other tribes.2 The stature and strength of the men of a tribe are likewise of some importance for its sue- 9 After a time the members, or tribes, which are absorbed into an- 154 THE DESCENT OF MAN. [Part I cess, 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, shows that from the remotest times successful tribes have sup- planted other tribes. Relics of extinct or forgotten tribes have been discovered throughout the civilized regions of the earth, on the wild plains of America, and on the iso- lated islands in the Pacific Ocean. At the present day civilized nations are everywhere supplanting barbarous nations, excepting where the climate opposes a deadly bar- rier* 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 in- tellectual faculties have been gradually perfected through natural selection ; and this conclusion is sufficient for our purpose. Undoubtedly it would have been very inter- esting to have traced the development of each separate faculty from the state in which it exists in the lower animals to that in which it exists in man ; but neither my ability nor knowledge permits the attempt. It deserves notice that as soon as the progenitors of man became social (and this probably occurred at a very early period), the advancement of the intellectual faculties will have been aided and modified in an important manner, of which we see only traces in the lower animals, namely, through the principle of imitation, together with reason other tribe assume, as Mr. Maine remarks ('Ancient Law,' 18G1, p. 131), that they are the co-descendants of the same ancestors. 3 Morlot, ' Soc. Yaud. Sc. Nat.' 1860, p. 294 Chap. V.] INTELLECTUAL FACULTIES. 155 and experience. Apes are much given to imitation, as are the lowest savages ; and the simple fact, previously re- ferred to, that after a time no animal can be caught in the same place by the same sort of trap, shows that animals learn by experience, and imitate each other's caution. Now, if some one man in a tribe, more sagacious than the others, invented a new snare or weapon, or other means of attack or defence, the plainest self-interest, without the assistance of much reasoning power, would prompt the other members to imitate him ; and all would thus profit. The habitual practice of each new art must likewise in some slight degree strengthen the intellect. If the new invention were an important one, the tribe would increase in number, spread, and 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 in- ventive members. If such men left children to inherit their mental superiority, the chance of the birth of still more ingenious members would be somewhat better, and in a very small tribe decidedly better. Even if they left no children, the tribe would still include their blood- relations ; and it has been ascertained by agriculturists 4 that by preserving and breeding from the family of an animal, which when slaughtered was found to be valuable, the desired character has been obtained. Turning now to the social and moral faculties. In order that primeval men, or the ape-like progenitors of man, should have become social, they must have acquired the same instinctive feelings which impel other animals to live in a body; and they no doubt exhibited the same general disposition. They would have felt uneasy when separated from their comrades, for whom they would have * I have given instances in my ' Variation of Animals under Domesti- cation,' vol. ii. p. 196. 156 THE DESCENT OF MAN. [Part I. 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, fidel- ity, and courage. Such social qualities, the paramount importance of which to 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, in the never- ceasing wars of savages, fidelity and courage must be. The advantage which disciplined soldiers have over un- disciplined hordes follows chiefly from the confidence which each man feels in his comrades. Obedience, as Mr. Bagehot has well shown,6 is of the highest value, for any form of government is better than none. Selfish and con- tentious people will not cohere, and without coherence nothing can be effected. A tribe possessing the above qualities in a high degree would spread and be victorious over other tribes; but in the course of time it would, judging from all past history, be in its turn overcome by some other and still more highly-endowed tribe. Thus the social and moral qualities would tend slowly to ad- vance and be diffused throughout the world. But it may be asked, How within the limits of the same tribe did a large number of members first become endowed with these social and moral qualities, and how was the standard of excellence raised ? It is extremely 6 See a remarkable series of articles on Physics and Politics in the Fortnightly Review,' Nov. 1867; April 1, 1868 ; July 1, 1869. Chap. V.] MORAL FACULTIES. 15 7 doubtful whether the offspring of the more sympathetic and benevolent parents, or of those which were the most faithful to their comrades, would be reared in greater number than the children of selfish and treacherous par- ents 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. The bravest men, who were always willing to come to the front in war, and who freely risked their lives for others, would on an average perish in larger num- ber than other men. Therefore it seems scarcely possible (bearing in mind that we are not here speaking of one tribe being victorious over another) that the number of men gifted with such virtues, or that the standard of their excellence, could be increased through natural selection, that is, by the survival of the fittest. 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 rea- soning powers and foresight of the members became im- proved, 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 of aiding his fellows ; and the habit of performing benevolent actions certainly strengthens the feeling of sympathy, which gives the first impulse to benevolent ac- tions. Habits, moreover, followed during many genera- tions probably tend to be inherited. But there is another and much "more powerful stimulus to the development of the social virtues, namely, the praise and the blame of our fellow-men. The love of ap- probation and the dread of infamy, as well as the be- stoAval of praise or blame, are primarily due, as we have 6een in the third chapter, to the instinct of sympathy ; 158 THE DESCENT OF MAN. [Part! and this instinct no doubt was originally acquired, like all the other social instincts, through natural selection. At how early a period the progenitors of man, in the course of their development, became capable of feeling 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 decora- tions ; for unless they regarded the opinion of their com- rades, 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 recol- lect any recorded instances of this feeling in savages ; and Sir J. Lubbock 6 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 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 him- self up as a prisoner rather than break his parole,7 would not feel remorse in his inmost soul, though he might con- ceal it, if he 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 of conduct 6 'Origin of Civilization,' 1870, p. 2G5. 7 Mr. Wallace gives cases in his ' Contributions to the Theory of Natural Selection,' 1870, p 354. Chap. V.] MORAL FACULTIES. 159 which appeared to them to be for the general good, and would reprobate that which appeared evil. To do good unto others — to do unto others as ye would they should do unto you — is the foundation-stone of morality. It is, therefore, hardly possible to exaggerate the importance during rude times of the love of praise and the dread of blame. A man who was not impelled by any deep, in- stinctive feeling, to sacrifice his life for the good of others, yet was roused to such actions by a sense of glory, would by his example excite the same wish for glory in other men, and would strengthen by exercise the noble feeling of admiration. He might thus do far more good to his tribe than by begetting offspring with a tendency to in- herit 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, etc., which during early times are, as we have before seen, utterly disregarded, come to be highly esteemed or even held sacred. I need not, however, repeat what I have said on this head in the third chapter. Ultimately a highly-complex sentiment, having its first origin in the social instincts, largely guided by the approbation of our fellow-men, ruled by reason, self-interest, and in later times by deep religious feelings, confirmed by instruction and habit, all combined, constitute our moral sense or con- science. 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 160 THE DESCENT OF MAN. [Part I. degree the spirit of patriotism, fidelity, obedience, courage, and sympathy, were always ready to give aid to each other and to sacrifice themselves for the common good, would be victorious over most other tribes ; and this would be natural selection. At all times throughout the world tribes have supplanted other tribes ; and as morali- ty is one element in their success, the standard of morality and the number of well-endowed men will thus every- where tend to rise and increase. It is, however, very difficult to form any judgment why one particular tribe and not another has been success- ful and has risen in the scale of civilization. Many sav- ages are in the same condition as when first discovered several centuries a«;o. As Mr. Basrehot 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, Mr. Maine,8 " the greatest part of mankind has never shown a particle of desire that its civil institutions should be im- proved." Progress seems to depend on many concurrent favorable conditions, far too complex to be followed out. But it has often been remarked, that a cool climate from leading to industry and the various arts has been highly favorable, or even indispensable for this end. The Esqui- maux, 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. While observing the barbarous inhabitants of Tierra del Fuego, it struck me that the possession of some property, a fixed abode, and the union of many fami- 8 'Ancient Law,' 1861, p. 22. For Mr. Bagehot's remarks, 'Fort- uightly Review,' April 1, 1868, p. 452. Chap. V.] CIVILIZED NATIONS. 161 lies under a chief, were the indispensable requisites for civilization. Such habits almost necessitate the cultiva- tion of the ground ; and the first steps in cultivation would probably result, as I have elsewhere shown,9 from some such accident as the seeds of a fruit-tree fallins: on a heap of refuse and producing an unusually fine variety. The problem, however, of the first advance of saArages toward civilization is at present much too difficult to be solved. Natural Selection as affecting Civilized Nations. — In the last and present chapters I have considered the ad- vancement of man from a former semi-human condition to his present state as a barbarian. But some remarks on the agency of natural selection on civilized nations may be here worth adding. This subject has been ably discussed by Mr. W. R. Greg,10 and previously 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 sur- vive commonly exhibit a vigorous state of health. We civilized men, on the other hand, do our utmost to check the process of elimination ; we build asylums for the im- 9 ' The Variation of Animals and Plants under Domestication,' vol. L p. 309. 10'Fraser's Magazine,' Sept. 1868, p. 353. This article seems to have struck many persons, and has given rise to two remarkable essays and a rejoinder in the ' Spectator,' Oct. 3 and 17, 1868. It has also been discussed in the ' Q. Journal of Science,' 1869, p. 152, and by Mr. Lawson Tait in the 'Dublin Q. Journal of Medical Science,' Feb. 1869, and by Mr. E. Ray Lankester in his ' Comparative Longevity,' 1870, p. 128. Similar views appeared previously in the 'Australasian,' July 13, 1867. I have borrowed ideas from several of these writers. 11 For Mr. Wallace, see ' Anthropolog. Review,' as before cited. Mr. Galton in ' Macmillan's Magazine,' Aug. 1S65, p. 318 ; also his great work, 'Hereditary Genius,' 1870. 8 162 THE DESCENT OF MAN. [Part! becile, 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 civilized socie- ties propagate their kind. ISTo 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 sur- prising how soon a want of care, or care wrongly directed, leads to the degeneration of a domestic race ; but except- ing in the case of man himself, hardly any one is so igno- rant as to allow his worst animals to breed. The aid which we feel impelled to give to the helpless is mainly an incidental result of the instinct of sympathy, which was originally acquired as part of the social in- stincts, but subsequently rendered, in the manner pre- viously indicated, more tender and more widely diffused. Nor could we check our sympathy, if so urged by hard reason, without deterioration in the noblest part of our nature. The surgeon may harden himself while perform- ing an operation, for he knows that he is acting for the goo*d of his patient ; but if we were intentionally to neg- lect the weak and helpless, it could only be for a con- tingent 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 indefinitely increased, though this is more to be hoped for than expected, by the weak in body or mind refraining from marriage. In all civilized countries man accumulates property and bequeaths it to his children. So that the children in Coap. Y.] CIVILIZED NATIONS. 163 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 civilized races have extended, and are now everywhere extending, their range, so as to take the place of the lower races. Nor does the moderate accumulation of wealth interfere with the process of selection. When a poor man becomes rich, his children enter trades or professions in which there is struggle enough, so that the able in body and mind succeed best. The presence of a body of well- instructed men, who have not to labor 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 advan- tages. No doubt wealth, when very great, tends to con- vert men into useless drones, but their number is never large ; and some degree of elimination 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 advantage 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, while 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 else- where, the relations of civilized 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 consequences, such as they may be, of 164 THE DESCENT OF MAN. [Part 1. the continued preservation of the same line of descent, without any selection, are checked by men of rank always wishing to increase their wealth and power ; and this they effect by marrying heiresses. But the daughters of parents who have produced single children, are themselves, as Mr. Galton has shown,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 superiority of any kind. Although civilization thus checks in many ways the action of natural selection, it apparently favors, by means of improved food and the freedom from occasional hard- ships, the better development of the body. This may be inferred from civilized men having been found, wherever compared, to be physically stronger than savages. They appear also to have equal powers of endurance, as has been proved in many adventurous expeditions. Even the great luxury of the rich can be but little detrimental ; for the expectation of life of our aristocracy, at all ages and of both sexes, is very little inferior to that of healthy Eng- lish lives in the lower classes.13 We will now look to the intellectual faculties alone. If in each grade of society the members were divided into two equal bodies, the one including the intellectually superior and the other the inferior, there can be little doubt that the former would succeed best in all occupa- tions and rear a greater number of children. Even in the lowest walks of life, skill and ability must be of some ad- vantage, though in many occupations, owing to the great division of labor, a very small one. Hence in civilized nations there will be some tendency to an increase both 12 'Hereditary Genius,' 1S70, pp. 132-140. 13 See the fifth and sixth columns, compiled from good authorities, in the table given in Mr. E. R. Lankester's ' Comparative Longevity,' 1 870, p. 115. CnAP. V.] CIVILIZED NATIONS. ]G5 in the number and in the standard of the intellectually able. But I do not wish to assert that this tendency may not be more than counterbalanced in other ways, as by the multiplication of the reckless and improvident; but even to such as these, ability must be some advantage. It has often been objected to views like the foregoing, that the most eminent men who have ever lived have left no offspring to inherit their great intellect. Mr. Galton says,14 " I regret I am unable to solve the simple question whether, and how far, men and women who are prodigies of genius are infertile. I have, however, shown that men of eminence are by no means so." 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 nu- merous 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 preservation 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 somewhat more able men in each grade of society succeeding rather better than the less able, and conse- quently increasing in number, if not otherwise prevented. When in any nation the standard of intellect and the number of intellectual men have increased, we mav ex- pect from the law of the deviation from an average, as shown by Mr. Galton, that prodigies of genius will appear somewhat more frequently than before. In regard to the moral qualities,-. some elimination of the worst dispositions is always in progress even in the most civilized nations. Malefactors are executed, or im- prisoned for long periods, so that they cannot freely trans 14 'Hereditary Genius,' 1870, p. 330. 15 Origin of Species' (fifth edition, 1869), p. 104. 106 THE DESCENT OF MAN. [Part I. mit their bad qualities. Melancholic and insane persons are confined, or commit suicide. Violent and quarrel- some 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 civilization 16 — emigrate to newly-settled countries, where they prove useful pioneers. Intemperance is so highly destructive, that the expecta- tion of life of the intemperate, at the age, for instance, of thirty, is only 13.8 years; while for the rural laborers of England at the same age it is 40.59 years.17 Profligate women bear few children, and profligate men rarely marry ; both suffer from disease. In the breeding of do- mestic animals, the elimination of those individuals, though few in number, which are in any marked manner inferior, is by no means an unimportant element toward 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 we are not removed by very many generations. This view seems indeed recognized in the common expression that such men are the black sheep of the family. With civilized nations, as far as an advanced stand- ard of morality, and an increased number of fairly well- endowed men are concerned, natural selection apparently effects but little; though the fundamental social instincts were originally thus gained. But I have already said enough, while treating of the lower races, on the causes 16 'Hereditary Genius,' 1870, p. 317. 17 E. Ray Lankester, 'Comparative Longevity,' 1S70, p. 115. The table of the intemperate is from Neison's ' Vital Statistics.' In regard to profligacy, see Dr. Farr, " Influence of Marriage on Mortality," ' Nat Assoc, for the Promotion of Social Science,' 1858. Chap. V.] CIVILIZED NATIONS. 167 which lead to the advance of morality, namely, the ap- probation of our fellow-men — the strengthening of our sympathies by habit — example and imitation — reason — experience and even self-interest — -instruction during youth, and religious feelings. A most important obstacle in civilized countries to an increase in the number of men of a superior class has been strongly urged by Mr. Greg and Mr. Galton,18 namely, the fact that the very poor and reckless, who are often degraded by vice, almost invariably marry early, while the careful and frugal, who are generally otherwise virtu- ous, marry late in life, so that they may be able to sup- port themselves and their children in comfort. Those who marry early produce within a given period not only a greater number of generations, but, as shown by Dr. Duncan,19 they produce many more children. The chil- dren, moreover, that are born by mothers during the prime of life are heavier and larger, and therefore prob- ably more vigorous, than those born at other periods. Thus the reckless, degraded, and often vicious members of society, tend to increase at a quicker rate than the provident and generally virtuous members. Or as Mr. Greg pats the case: "The careless, squalid, unaspiring Irishman multiplies like rabbits : the frugal, foreseeing, self-respecting, ambitious Scot, stern in his morality, spir- itual in his faith, sagacious and disciplined in his intelli- gence, 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 18'Frascr's Magazine,' Sept. 18G8, p. 353. 'Macmillan's Magazine,' Aug. 1SG5, p. 318. The Rev. F. W. Farrar (' Eraser's Mag.,' Aug. 1870, p, 2G1) takes a different view. 19 " On the Laws of the Fertility of Women," in ' Transact. Royal Soc.' Edinburgh, vol. xxlv. p. 287. See, also, Mr. Galton, 'Hereditary Genius,' pp. 352-357, for observations to the above effect. L68 THE DESCENT OF MAN. [Tart I. Celts — and in a dozen generations five-sixths of the popu- lation would he Celts, hut five»-sixths of the property, of the power, of the intellect, would helong to the one-sixth of Saxons that remained. In the eternal ' struggle for existence,' it would be the inferior and less favored 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 from a high rate of mortality, and the extremely profligate leave few offspring. The poorest classes crowd into towns, and it has been proved by Dr. Stark from the statistics of ten years in Scotland,20 that at all ages the death-rate is higher in towns than in rural districts, "and during the first five years of life the town death-rate is almost ex- actly 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 inhabitants in the towns, relatively to those in the country. "With women, mar- riage at too early an age is highly injurious ; for it has been found in France that " twice as many wives under twenty die in the year, as died out of the same number of the unmarried." The mortality, also, of husbands un- der twenty is " excessively high," 21 but what the cause of this may be seems doubtful. Lastly, if the men who pru- dently delay marrying until they can bring up their families in comfort, were to select, as they often do, wo- men 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, 20 'Tenth Annual Eepor-t of Births, Deaths, etc., in Scotland,' 1S67, p. xxix. 21 These quotations are taken from our highest authority on such questions, namely, Dr. Farr, in his paper " On the Influence of Marriage Chap. V.] CIVILIZED NATIONS. 109 taken during 1853, that the unmarried men throughout France, between the ages of twenty and eighty, die in a much larger proportion than the married: for instance, out of every 1,000 unmarried men, between the ages of twenty and thirty, 11.8 annually died, while of the married only 6.5 died.22 A similar law was proved to hold good, during the years 1863 and 1864, with the entire popula- tion above the age of twenty in Scotland : for instance, out of every 1,000 unmarried men, between the ages of twenty and thirty, 14.97 annually died, while of the mar- ried only 7.24 died, that is, less than half.23 Dr. Stark re- marks on this : " Bachelorhood is more destructive to life than the most unwholesome trades, or than residence in an unwholesome house or district where there has never been the most distant attempt at sanitary improvement." He considers that the lessened mortality is the direct re- sult of " marriage, and the more regular domestic habits which attend that state." He admits, however, that the intemperate, profligate, and criminal classes, whose dura- tion of life is low, do not commonly marry ; and it must likewise be admitted that men with a weak constitution, ill health, or any great infirmity in body or mind, will often not wish to marry, or will be rejected. Dr. Start seems to have come to the conclusion that marriage in itself is a main cause of prolonged life, from finding that aged married men still have a considerable advantage in this respect over the unmarried of the same advanced age ; on the Mortality of the French People," read before the Nat. Assoc, for the Promotion of Social Science, 1858. 22 Dr. Farr, ibid. The quotations given below are extracted from the same striking paper. 23 I have taken the mean of the quinquennial means, given in The Tenth Annual Report of Births, Deaths, etc., in Scotland,' 1867. The quotation from Dr. Stark is copied from an article in the ' Daily News,' Oct. 17, 1868, which Dr. Farr considers very carefully written. 170 THE DESCENT OF MAN. [Fart I. but every one must have known instances of men, who with weak health during youth did not marry, and yet have survived to old age, though remaining weak and there- fore always with a lessened chance of life. There is anoth- er remarkable circumstance which seems to support Dr. Stark's conclusion, namely, that widows and widowers in France suffer in comparison with the married a very heavy rate of mortality ; but Dr. Farr attributes this to the pov- erty and evil habits consequent on the disruption of the family, and to grief. On the whole we may conclude with Dr. Farr that the lesser mortality of married than of un- married 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, intellect ual, and moral qualities. We may, therefore, infer that sound and good men who out of prudence remain for a time un- married do not suffer a high rate of mortality. If the various checks specified in the two last paragraphs, and perhaps others as yet unknown, do not prevent the reck- less, the vicious, and otherwise inferior members of society from increasing at a quicker rate than the better class of men, the nation will retrograde, as has occurred too often in the history of the world. "We must remember that prog- ress is no invariable rule. It is most difficult to say why one civilized nation rises, becomes more powerful, and spreads more widely, than another; or why the same nation pro- gresses 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 with high in- tellectual and moral faculties, as well as on their standard of excellence. Corporeal structure, except so far as vigor of body leads to vigor of mind, appears to have little influence. It has been urged by several writers that as high in- Chap. V.] CIVILIZED NATIONS. 171 tellectual powers are advantageous to a nation, the old Greeks, who stood some grades higher in intellect than any race that has ever existed,24 ought to have risen, if the power of natural selection were real, still higher in the scale, increased in number, and stocked the whole of Eu- rope. Here we have the tacit assumption, so often made with respect to corporeal structures, that there is some in- nate tendency toward continued development in mind and body. But development of all kinds depends on many concurrent favorable circumstances. 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 ex- treme sensuality ; for they did not succumb until " they were enervated and corrupt to the very core."25 The western nations of Europe, who now so immeasurably sur- pass their former savage progenitors and stand at the sum- mit of civilization, 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. Gait on20 has remarked, almost all the men of a gentle 24 See the ingenious and original argument on this subject by Mr. Galton, ' Hereditary Genius,' pp. 340-342. , 25 Mr. Greg, 'Fraser's Magazine,' Sept. 1868, p. 357. 26 ' Hereditary Genius,' 1870, pp. 357-359. The Kev. F. H. Farrar (' Fraser's Mag.', Aug. 1870, p. 257) advances arguments on the other side. Sir C. Lyell had already (' Principles of Geology,' vol. ii. 1868, p. 489) called attention, in a striking passage, to the evil influence of tho 172 THE DESCENT OF MAN. [Part I. nature, those given to meditation or culture of the mind, had no refuge except in the bosom of the Church which demanded celibacy ; and this could hardly fail to have had a deteriorating influence on each successive generation. During this same period the Holy Inquisition selected with extreme care the freest and boldest men in order to burn or imprison them. In Spain alone some of the best men — - those who doubted and questioned, and without doubting there can be no progress — were eliminated during three centuries at the rate of a thousand a year. The evil which the Catholic Church has thus effected, though no 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 over other European nations, which is well illustrated by comparing the progress of the Canadians of English and French extraction, has been ascribed to their " daring and persistent energy ; " but who can say how the English gained their energy ? There is apparently much truth in the belief that the wonderful progress of the United States, as well as the character of the people, are the results of natural selection ; the more energetic, restless, and coura- geous men from all parts of 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 not 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 Holy Inquisition in having lowered, through selection, the general stand- ard of intelligence in Europe. 27 Mr. Galton, ' Macmillan's Magazine,' August, 1865, p. 325. Seq also, ■ Nature,' " On Darwinism and National Life," Dec. 1869, p. 184. &? ' Last Winter in the United States,' 1868, p. 29. Chap. V.] CIVILIZED NATIONS. 173 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." Obscure as is the problem of the advance of civilization, we can at least see that a nation which produced during a lengthened period the greatest number of highly intellec- tual, energetic, brave, patriotic, and benevolent men, would generally prevail over less favored nations. Natural selection follows from the struggle for exist- ence ; and this from a rapid rate of increase. It is impos- sible 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 infanticide and many other evils, and in civilized 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, lie has no right to expect an immunity from the evils con- sequent on the struggle for existence. Had he 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 fer- tile land peopled by a few wandering savages, but which are capable of supporting numerous happy homes, it might be argued that the struggle for existence had not been sufficiently severe to force man upward to his highest standard. Judging from all that we know of man and the lower animals, there has always been sufficient variability m the intellectual and moral faculties, for their steady ad- vancement through natural selection. No doubt such advancement demands many favorable concurrent circum- stances ; but it may well be doubted whether the most favorable would have sufficed, had not the rate of increase been rapid, and the consequent struggle for existence severe to an extreme degree. 174 THE DESCENT OF MAN. [Part I. On the evidence that all civilized nations were once barbarous. — As we have had to consider the steps by which 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. Lub- bock,29 Mr. Tylor, Mr. M'Lennan, and others, that I need here give only the briefest summary of their results. The arguments recently advanced by the Duke of Argyll30 and formerly by Archbishop Whately, in favor of the be- lief that man came into the world as a civilized being and that all savages have since undergone degradation, seem to me weak in comparison with those advanced on the other side. Many nations, no doubt, have fallen away in civilization, and some may have lapsed into utter bar- barism, though on this latter head I have not met with any evidence. The Fuegians were probably compelled by other conquering hordes to settle in their inhospitable country, and they may have become in consequence some- what more degraded ; but it would be difficult to prove that they have fallen much below the Botocudos who in- habit the finest parts of Brazil. The evidence that all civilized nations are the de- scendants of barbarians, consists, on the one side, of clear traces of their former low condition in still-existing cus- toms, beliefs, language, etc. ; and, on the other side, of proofs that savages are independently able to raise them- selves a few steps in the scale of civilization, 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 enumeration, which, as Mr. Tylor clearly shows by the words still used 29 ' On the Origin of Civilization,' ' Froc. Ethnological Soc.' Nov. 2G, 1867. 30 ' Primeval Man,' 18G9. Chap. V.] CIVILIZED NATIONS. 1 ?5 in some places, originated in counting the fingers, first of one hand and then of the other, and lastly of the toes. We have traces of this in our own decimal system, and in the Roman numerals, which after reaching to the number V., change into VI., etc., when the other hand no doubt was used. So again, "when we speak of threescore and ten, we are counting by the vigesimal system, each score thus ideally made, standing for 20 — for 'one man' as a Mexican or Carib would put it." 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'Len- nan's work32 and not admit that almost all civilized 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 shown 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. The 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. Lubbock has shown that some savages have recently improved a little in some of their simpler arts. From the extremely 31 ' Royal Institution of Great Britain,' March 15, 1867. Also, 'Re- searches into the Early History of Mankind,' 1865. 32 ' Primitive Marriage,' 1865. See, likewise, an excellent article, evidently by the same author, in the ' North'British Review,' July, 1869. Also, Mr. L. II. Morgan, "A Conjectural Solution of the Qrigin of the Class. System of Relationship," in ' Proc. American Acad, of Sciences,' vol. vii. Feb. 186S. Prof. Schaaffhauscn (' Anthropolog. Review,' Oct. 1S69, p. 3*73) remarks on "the vestiges of human sacrifices found both in Homer and the Old Testament." 17G THE DESCENT OF MAN. [Pakt I. 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 perhaps the art of making fire.33 The Australian boomerang is a good in- stance 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 cul- tivated, and a few native animals domesticated. We should bear in mind that a wandering: crew from some semi-civilized land, if washed to the shores of America, would not, judging from the small influence of most mis- sionaries, have produced 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 use Sir J. Lubbock's well-known terms, a paleolithic and neolithic period; and no one will pretend that the art of grinding: rouerh flint tools was a borrowed one. In all parts of Europe, as far east as Greece, in Pal- estine, India, Japan, New Zealand, and Africa, including Egypt, flint tools have been discovered in abundance ; and of 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 doubt that the inhabitants of these many countries, which include nearly the whole civilized world, were once in a barbarous condition. To believe that man was aboriginally civilized and then suffered utter degradation in so many 33 Sir J. Lubbock, 'Prehistoric Times,' 2d edit. 1SG9, chaps, xv. and xvi. ei passim. 34 Dr. F. Midler has made some good remarks to this effect in the Reise der Novara : Anthropolog. Theil,' Abtheil. iii. 1S68, s. 127. Chap. V.] CIVILIZED NATIONS. 177 regions, is to take a pitiably low view of human nature. It is apparently a truer and more cheerful view that prog- ress 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. 178 THE DESCENT OF MAN. [Part I. CHAPTER VI. ON THE AFFINITIES AND GENEALOGY OF MAN. Position of Man in the Animal Series. — The Natural System genealogical. — Adaptive Characters of Slight Value. — Various Small Points of Re- semblance between Man and the Quadrumana. — Eank of Man in the Natural System. — Birthplace and Antiquity of Man. — Absence of Fossil Connecting-links. — Lower Stages in the Genealogy of Man, as inferred, firstly from his Affinities and secondly from his Structure. — Early Androgynous Condition of the Vertebrata. — Conclusion. Even if it be granted that the difference between man and his 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 de- clare, as it appears to me, in the plainest maimer, that man is descended from some lower form, notwithstanding that connecting-links have not hitherto been discovered. Man is liable to numerous, slight, and diversified varia- tions, which are induced by the same general causes, are governed and transmitted in accordance with the same general laws, as in the lower animals. Man tends to mul- tiply at so rapid a rate that his offspring are necessarily exposed to a struggle for existence, and consequently to natural selection. He has given rise 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 homological plan as that of other mammals, Chap. VI.] AFFINITIES AND GENEALOGY. 179 independently of the uses to which the several parts may- be put. He passes through the same phases of embryo- logical development. He retains many rudimentary and useless structures, which no doubt were once serviceable. Characters occasionally make their reappearance 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 va- rious 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 compared or classed by the naturalist ; but Ije may endeavor to show, as I have done, that the mental faculties of man and the lower ani- mals 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 undoubtedly 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, while young, attaches itself by its proboscis to a plant ; sucks the sap, but never moves again ; is fertilized and lays eggs ; and this is its whole history. On the other hand, to describe the habits and mental powers of a 1 Isidore GeoiTroy St.-Hilaire gives a detailed account of the position assigned to man by various naturalists in their classifications : ' Hist Nat. Gen.' torn. ii. 1S59, pp. 170-189. [80 THE DESCENT OF MAN. [Part I. female ant, would require, as Pierre Huber has shown, 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 recog- nize their fellow-ants after months of absence. They build great edifices, keep them clean, close the doors in the even- ing, and post sentries. They make roads, and even tun- nels 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 afterward build it up again.2 They go out to battle in regular bands, and free- ly sacrifice their lives for the common weal. They emi- grate in accordance with a preconcerted plan. They cap- ture 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 others 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 become extinct. Prof. Owen, relying chiefly on the structure of thr- brain, has divided the mammalian series into four sub classes. One of these he devotes to man ; in another h( places both the marsupials and the monotremata ; so that he makes man as distinct from all other mammals as are these two latter groups conjoined. This view has not been accepted, as far as I am aware, by any naturalist 2 See the very interesting article, " L'Instinct chez les Insects," bj M. George Pouchet, 'Revue des Deux Mondes,' Feb. 1870, p. 682. Chap. VI.] AFFINITIES AND GENEALOGY. 181 capable of forming an independent judgment, and there- fore need not here be further considered. "We can understand why a classification founded on any single character or organ — even an organ so wonder- fully 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 thor- oughly artificial.3 Classifications may, of course, be based on any character whatever, as on size, color, or the ele- ment inhabited ; but naturalists have long felt a profound conviction that there is a natural system. This system, it is now generally admitted, must be, as far as possible, genealogical in arrangement — that is, the co-descendants of the same form must be kept together in one group, sep- arate 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 under- gone— 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 resemblance between the beings which are to be classed. For this object numerous points of resem- blance are of much more importance than the amount of similarity or dissimilarity in a few points. If two lan- onia^es were found to resemble each other in a multitude of words and points of construction, they would be uni- versally recognized as having sprung from a common source, notwithstanding that they differed greatly in some few words or points of construction. But with organic beings the points of resemblance must not consist of 3 Westwood, ' Modern Class, of Insects,' vol. ii. 1840, p. 87. 182 THE DESCENT OF MAN. [Part I. 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 modifica- tion in some one character ought not to lead us to sepa- rate widely any two organisms. A part which already differs much from the same part in other allied forms has already, according to the theory of evolution, varied much ; consequently it would (as long as the organism remained exposed to the same exciting conditions) 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, of the beak of a bird, or the teeth of a mammal, would not be advantageous to the species for gaining its food, or for any other object ; but with man we can see no definite limit, as far as advantage is con- cerned, to the continued development 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 multi- tude of resemblances in other less important or quite un- important points. The greater number of naturalists who have taken into consideration the whole structure of man, including bis mental faculties, have followed Blumenbach and Cu- vier, and have placed man in a separate Order, under the title of the Bimana, and therefore on an equality with the Chap VI.] AFFINITIES AND GENEALOGY. 183 Orders of the Quadrumana, Carnivora, etc. Recently many of our best naturalists have recurred to the view first propounded by Linnaeus, so remarkable for his sa-t gacity, 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, we bear in mind the remarks just made on the comj)ara- tively small importance for classification of the great de- velopment of the brain in man; bearing, also, in mind that the strongly-marked differences between the skulls of man and the Quadrumana (lately insisted upon by Bi- schoff, Aeby, and others) apparently follow from their dif- ferently-developed brains. In the second place, we must remember that - nearly all the other and more important differences between man and the Quadrumana are mani- festly 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 po- sition of his head. The family of seals offers a good il- lustration of the small importance of adaptive characters for classification. These animals differ from all other Car- nivora 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 re- cent one by Mr. Flower,4 seals are ranked as a mere family in the Order of the Carnivora. If man had not been his own classifier, he would never have thought of founding a separate order for his own reception. It would be beyond my limits, and quite beyond my knowledge, even to name the innumerable points of struct- ure in which man agrees with the other Primates. Our great anatomist and philosopher, Prof. Huxley, has fully discussed this subject,6 and has come to the conclusion * « Froc. Zoolog. Soc.' 1869, p. 4. 6 'Evidence as to Man's Place jn Nature,' 18G3, p. 10, et passim. 184 THE DESCENT OF MAN. [Part I. that man in all parts of his organization differs less from the higher apes, than these do from the lower members of , the same group. Consequently there " is no justification for placing man in a distinct order." In an early part of this volume I brought forward various facts, showing how closely man agrees in consti- tution with the higher mammals ; and this agreement, no doubt, depends on our close similarity in minute structure and chemical composition. I gave, as instances, our lia- bility to the same diseases, and to the attacks of allied parasites ; our tastes in common for the same stimulants, and the similar effects thus produced, as well as by various drugs ; and other such facts. As small unimportant points of resemblance between man and the higher apes are not commonly noticed in systematic works, and as, when numerous, they clearly reveal our relationship, I will specify a few such points. The relative positions of the features are manifestly the same in man and the Quadrumana ; and the various emo- tions are displayed by nearly similar movements of the muscles and skin, chiefly above the eyebrows and round the mouth. Some few expressions are, indeed, almost the same, as in the weeping of certain kinds of monkeys, and in the laughing noise made by others, during which the corners of the mouth are drawn backward, and the lower eyelids wrinkled. The external ears are curiously alike. In man the nose is much more prominent than in most mon- keys ; but we may trace the commencement of an aquiline curvature in the nose of the Hoolock Gibbon ; and this in the Semnopithecus nasica is carried to a ridiculous extreme. The faces of many monkeys are ornamented with beards, whiskers, or mustaches. The hair on the head grows to a great length in some species of Semnopithe- cus ; 6 and in the Bonnet monkey (Macacus radlatus) it 6 Isid. Geoffroy, ' Hist. Nat. Gen.' torn. ii. 1859, p. 217 Chap. VI.] AFFINITIES AND GENEALOGY. 185 radiates from a point on the crown, with a parting down the middle, as in man. It is commonly said that the fore- head gives to man his noble and intellectual appearance ; but the thick hair on the head of the Bonnet monkey ter- minates abruptly downward, 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 has been erroneously asserted that eye- brows are not present in any monkey. In the species just named the decree 0f nakedness of the forehead differs in different individuals, and Eschricht states 7 that in our children the limit between the hairy scalp and the naked forehead is sometimes not well defined ; so that here we seem to have a trifling case of reversion to a progenitor, in whom the forehead had not as yet become quite naked. It is well known that the hair on our arms tends to converge from above and below to a point at the elbow. 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 hair on the forearm is directed downward or toward the wrist in the ordinary manner ; and in II. lar it is nearly erect, with only a very slight forward inclination ; so that in this latter species it is in a transitional state. It can hardly be doubted that with most mammals the thickness of the hair and its direction on the back is adapted to throw off tlje rain ; even the transverse hairs on the fore- legs of a dog may ^erve for this end when he is coiled up asleep. Mr. Wallace remarks that the convergence of the hair toward the elbow on the arms of the orang (whose habits he has so carefully studied) serves to throw off the rain, when, as is the custom of this animal, the arms are 1 " Ueber die Richluug der Ilaare," etc., Muller's ' Archiv fur Anat and Phys.' 1837, s. 51. 9 186 THE DESCENT OF MAN. [Part I. bent, with the hands clasped round a branch or over its own head. We should, however, bear in mind that the attitude of an animal may perhaps be in part determined by the direction of the hair; and not the direction of the hair by the attitude. If the above explanation is correct in the case of the orang, the hair on our forearms offers a curious record of our former state ; for no one supposes that it is now of any use in throwing off the rain, nor in our pres- ent 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 Eschricht of the arrange- ment of the hair on the human foetus (this being the same as in the adult) and not agree with this excellent observer that other and more complex causes have intervened. The points of convergence seem to stand in some relation to those points in the embryo which are last closed in during development. There appears, also, to exist some relation between the arrangement 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, etc. — are all necessarily the result of un- broken inheritance from a common progenitor thus charac- terized, or of subsequent reversion. Many of these resem- blances are more probably due to analogous variation, which follows, as I have elsewhere attempted to show,9 8 On the hair in Hylobates, see ' Nat. Hist, of Mammals,' by C. L. Martin, 1841, p. 415. Also, Isid. Geoffroy on the American monkeys and other kinds^ 'Hist. Nat. Gen.' vol. ii. 1859, pp. 216, 243. Eschricht, ibid, s. 46, 55, 61. Owen, ' Anat. of Vertebrates,' vol. iii. p. 619. Wallace, 'Contributions to the Theory of Natural Selection,' 18*70, p. 344. 9 ' Origin of Species,' 5th edit. 1869, p. 194. ' The Variation of Am- mals and Plants under Domestication,' voL ii. 1868, p. 348. Chap. VI.] AFFINITIES AND GENEALOGY. 187 from co-descended organisms having a similar constitution and having been acted on by similar causes inducing variability. "With respect to the similar direction of the hair on the forearms 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 characterized. 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 inheritance, as the tail, though not absent, is rudimentary in several other Old World and in some New World species, and is quite absent in 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 may perhaps claim a distinct Sub-order or Family. Prof. Hux- ley, in his last work,10 divides the Primates into three Sub- orders : namely, the Anthropida3 with man alone, the Simiada) including monkeys of all kinds, and the Lemu- ridae with the diversified genera of lemurs. As far as dif- ferences in certain important points of structure are con- cerned, man may no doubt rightly claim the rank of a Sub-order ; and this rank is too low, if we look chiefly to his mental faculties. Nevertheless, under a genealogical point of view it appears that this rank is too high, and that man ought to form merely a Family, or possibly even only a Sub-family. If we imagine three lines of descent proceeding from a common source, it is quite conceivable that two of them might after the lapse of ages be so slightly changed as still to remain as species of the same genus ; while the third line might become so greatly modified as to deserve to rank as a distinct Sub-family, 10 ' An Introduction to the Classification of Animals,' 1869, p. 99. 188 THE DESCENT OF MAN. [Part I. Family, or even Order. But in this case it is almost cer- tain that the third line would still retain through inheri- tance numerous small points of resemblance with the other two lines. Here, then, would occur the difficulty, at present insoluble, how much weight we ought to assign in our classifications to strongly-marked differences in some few points — that is, to the amount of modification under- gone ; and how much to close resemblance in numerous unimportant points, as indicating the lines of descent or genealogy. The former alternative is the most obvious, and perhaps the safest, though the latter appears the most correct as giving a truly natural classification. To form a judgment on this head, with reference to man we must glance at the classification of the SimiadaB. This family is divided by almost all naturalists into the Catarhine group, or Old World monkeys, all of which are characterized (as their name expresses) by the peculiar structure of their nostrils and by having four premolars in each jaw ; and into the Platyrhine group or New World "monkeys (including two very distinct sub-groups), all- of which are characterized by differently-constructed nostrils and by having six premolars in each jaw. Some other small differences might be mentioned. Now man unques- tionably belongs in his dentition, in the structure of his nostrils, and some other respects, to the Catarhine or Old W^orld division ; nor does he resemble the Platyrhines more closely than the Catarhines in any characters, ex- cepting 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 Sim- Chap. VI.] AFFINITIES AND GENEALOGY. 180 ian stem ; and that, under a genealogical point of view, he must be classed with the Catarhine division.11 The anthropomorphous apes, namely the gorilla, chim- panzee, 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 existence of this sub-group, and no doubt it is a broken one ; thus the orang, as Mr. St. G. Mivart remarks,12 " is one of the most peculiar and aberrant forms to be found in the order." The re- maining, non-anthropomorphous, 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 it appears from M. Gaudry's wonderful dis- coveries in Attica, that during the Miocene period a form existed there, which connected Semnopithecus and Maca- cus ; and this probably illustrates the manner in which the other 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, not 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 of callosities and in general appearance, we may infer that some ancient member of the anthropomorphous sub-group gave birth to man. It is not probable that a member of one of the other lower sub-groups should, through the law of analo- gous variation, have given rise to a man-like creature, 4 11 This is nearly the same classificatioH as that provisionally adopted by Mr. St. George Mivart ('Transact. Philosoph. Soc.' 1867, p. 300), who, after separating the Lemuridae, divides the remainder of the Primates into the Hominidce, the Simiadaj answering to the Catarhines, the Cebidoe, and the Hapalida) — these two latter groups answering to the Platyrhines. 12 'Transact. Zoolog. Soc' vol. vi. 1867, p. 214. 190 THE DESCENT OF MAN. [Part I. resembling the higher anthropomorphous apes in so many respects. No doubt man, in comparison with most of his allies, has undergone an extraordinary amount of modifi- cation, chiefly in consequence of his greatly-developed brain and erect position ; nevertheless, we should bear in mind that he " is but one of several exceptional forms of Primates." 13 Every naturalist, who believes in the principle of evolution, will grant that the two main divisions of the Simiada3, namely the Catarhine and Platyrhine monkeys, with their sub-groups, have all proceeded from some one extremely ancient progenitor. The early descendants of this progenitor, before they had diverged to any con- siderable extent from each other, would still have formed a single natural group ; but some of the species or incipi- ent genera would have already begun to indicate by their diverging characters the future distinctive marks of the Catarhine and Platyrhine divisions. Hence the members of this supposed ancient group would not have been so uniform in their dentition or in the structure of their nostrils, as are the existing Catarhine monkeys in one way and the Platyrhines in another way, but would have resembled in this respect the allied Lemurida? which differ greatly from each other in the form of their muzzles,14 and to an extraordinary degree in their dentition. The Catarhine and Platyrhine monkeys agree in a multitude of characters, as is shown 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 whicli possessed many characters 13 Mr. St. G. Mivart, « Transact. Pbil. Soc.' 1867, p. 410 14 Messrs. Murie am Soc' vol. vii. 1869, p. 5 14 Messrs. Murie and Mivart on the Leniuroidea, ' Transact. Zoolog, Chap. VI. J AFFINITIES AND GENEALOGY. 191 common to the Catarhine and Platyrhine 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 the Catarhine or Old World stock, we must conclude, however much the conclusion • may revolt our pride, that our early progenitors would have been properly thus designated.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 3Ian. — We are naturally led to inquire where was the birthplace of man at that stage of descent when our progenitors diverged from the Catarhine stock. The fact that they belonged to this stock clearly shows that they inhabited the Old World ; but not Australia nor any oceanic island, as we may infer from the laws of geographical distribution. In each great region of the world the living, mammals are closely related to the extinct species of the same region. It is therefore probable that Africa was formerly inhab- ited by extinct apes closely allied to the gorilla and chim- panzee ; and as these two species are now man's nearest allies, it is somewhat more probable that our early pro- genitors lived on the African Continent than elsewhere. But it is useless to speculate on this subject, for an ape nearly as large ' as a man, namely, the Dryopitbecus of Lartet, which was closely allied to the anthropomorphous 15 Ilackel has come, to this same conclusion. Sec ' Ucber die Ent- stehung des Mellschengeschlechts,, in Virchow's ' Sammlung. gemcin. wissen. Vortrage,' 1868, s. 61. Also his 'Natiirliehe Schopfungs- geschichte,' 1S68, in which he gives in detail his views on the genealogy of man. 192 THE DESCENT OF MAN. [Part I. Hylobates, existed in Europe during the Upper Miocene period; and since so remote a period the earth has cer- tainly undergone many great revolutions, and there has been ample time for migration on the largest scale. 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 favorable for a frugiferous diet, on which, judging from analogy, he subsisted. We are far from knowing how longj as;o 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 Mio- cene period, as shown by the existence of the Dryopithe- cus. We are also quite ignorant at how rapid a rate or- ganisms, whether high or low in the scale, may under favorable circumstances be modified : we know, however, that some have retained the same form during an enor- mous 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 of modification in certain characters in com- parison with the higher apes. The great break in the organic chain between man and his nearest allies, which cannot be bridged over by any extinct or living species, has often been advanced as a grave objection to the belief that man is descended from some lower form ; but this objection will not appear of much weight to those who, convinced by general reasons, believe in the general principle of evolution. Breaks in- cessantly occur in all j^arts of the series, some being wide, sharp, and defined, others less so in various degrees ; as between the orano- and its nearest allies — between the Chap. VI.] AFFINITIES AND GENEALOGY. ] 93 Tarsias and the other Lemurida3 — between the elephant and in a more striking manner between the Ornithorhyn- chus or 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 civilized races of man will almost certainly exterminate and replace throughout the world the savage races. At the same time the anthropomorphous apes, as Prof. Schaaffhausen has remarked,16 will no doubt be exterminated. The break will then be rendered wider, for it will intervene between man in a more civilized state, as we may hope, than the Caucasian, and some ape as low as a baboon, in- stead 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,17 in which he shows that in all the vertebrate classes the discovery of fossil remains has been an ex- tremely 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 Man. — "We have seen that man appears to have diverged from the Cata- rhine or Old World division of the SimiadeB, after these • had diverged from the ]STew World division. We will now endeavor to follow the more remote traces of his genealogy, trusting in the first place to the mutual affini- ties between the various classes and orders, with some 16 'Anthropological Review,' April, 18G7, p. 236. 17 'Elements of Geology,' 1865, pp. 583-585. 'Antiquity of Man,' 1863, p. 145. 194 THE DESCENT OF MAN. [Part I. Blight aid from the periods, as far as ascertained, of their successive appearance on the earth. The Lemuridce stand below and close to the Simiada3, constituting a very dis- tinct family of the Primates, or, according to Hackel, a distinct Order. This group is diversified and broken to an extraordinary degree, and includes many aberrant forms. It has, therefore, probably suffered much extinc- tion. 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 compe- tition as they would have been on well-stocked continents. This group likeAvise presents many gradations, leading, as Huxley remarks,18 " insensibly from the crown and sum- mit 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 Simiadae were originally develoj)ed from the progenitors of the ex- istino- Lemuridoe ; and these in their turn from forms stand- ing 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 now is. Hence the Placentata are generally supposed to have been derived from the Implacentata or Marsupials ; not, however, from forms closely like the existing Marsupials, but from their early progenitors. The Monotremata 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 Ornithorhynchus and Echidna ; and these two forms may be safely considered as relics of a much larger group which have been preserved in Austra- lia through some favorable concurrence of circumstances. 18 ' Man's Place in Nature,' p. 105. Chap. VI.] AFFINITIES AND GENEALOGY 195 The Monotremata are eminently interesting, as in several important points of structure they lead toward 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 washes to see what ingenuity and knowledge can effect, may consult Prof. Hackel's works.19 I will con- tent myself with a few general remarks. Every evolu- tionist will admit that the five 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 organized and ap- peared before the others, we may conclude that all the members of the vertebrate kingdom are derived from some fish-like animal, less highly organized than any as yet found in the lowest known formations. The belief that animals so distinct as a monkey or elephant and a hum- ming-bird, a snake, frog, and fish, etc., could all have sprung from the same parents, will appear monstrous to those wdio have not attended to the recent progress of natural history. For this belief implies the former ex- istence of links closely binding together all these forms, now so utterly unlike. Nevertheless, it is certain that groups of animals have existed, or do now exist, which serve to connect more or less closely the several great vertebrate classes. We have 19 Elaborate tables are given in bis ' Generelle Morpbologie ' (B. ii. b. cliii. and s. 425) ; and with more especial reference to man in his 'Natiirlichc Schopfungsgeschiehte,' 18G8. 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- cussed by Hackel, although he differs on some points. He expresses, also, his high estimate of the value of the general tenor and spirit of the whole work. 196 THE DESCENT OF MAN. [Part I. Been that the Ornithorhynchus graduates toward reptiles ; and Prof. Huxley has made the remarkable discovery, confirmed by Mr. Cope and others, that the old Dinosau- rians are intermediate in many important respects between certain reptiles and certain birds — the latter consisting of the ostrich-tribe (itself evidently a widely-diffused rem- nant 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 Ichthy- osaurians — great sea-lizards furnished with paddles — pre- sent 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-generalized type, that is, they pre- sented diversified affinities 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 Lepido- siren and some few Ganoid fishes have been preserved from utter extinction by inhabiting our rivers, which are harbors 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 lancelct or amphioxus, is so different from all other fishes, that Hiickel maintains that it ought to form a distinct class in the vertebrate kingdom. This fish is remarkable for its negative charac- ters ; it can hardly be said to possess a brain, vertebral col- umn, or heart, etc. ; so that it was classed by the older naturalists among* the worms. Many years ago Prof. Goodsir perceived that the lancelet presented some affini- ties with the Ascidians, which are invertebrate, hermaphro- 20 'Paleontology,' 18G0, p. 199. Chap. VI.] AFFINITIES AND GENEALOGY. 197 dite, marine creatures permanently attached to a support. They hardly appear like animals, and consist of a simple, tough, leathery sack, with two small projecting orifices. They belcmg to the Molluscoida of Huxley — a lower di- vision of the great kingdom of the Mollusca; but they have recently been placed by some naturalists among the Vermes or worms. Their larvaB somewhat resemble tad- poles in shape,21 and have the power of swimming freely about. Some observations lately made by M. Kowa- levsky,22 since confirmed by Prof. Kuppfer, will form a discovery of extraordinary interest, if still further ex- tended, as I hear from M. Kowalevsky in Naples he has now effected. The discovery is that the larvss of As- cidians are related to the Yertebrata, in their manner of development, in the relative position of the nervous sys- tem, and in possessing a structure closely like the chorda dorsalls of vertebrate animals. It thus appears, if we may rely on embryology, which has always proved the safest guide in classification, that we have at last gained a clew to the source whence the Vertebrata have been de- rived. We should thus be justified in believing that at an extremely remote period a group of animals existed, resembling in many respects the larva? of our present As- cidians, which diverged into two great branches — the one retrograding in development and producing the present 21 I had the satisfaction of seeing, at the Falkland Islands, in April, 1833, and therefore some years before any other naturalist, the locomo- tive larvae of a compound Ascidian, closely allied to, but apparently gen- erically distinct from, Synoicum. The tail was about five times as long as the oblong head, and terminated in a very fine filament. It was plainly divided, as sketched by me under a simple microscope, by trans- verse opaque partitions, which I presume represent the great cells figured by Kowalevsky. At an early stage of development the tail was closely coiled round the head of the larva. 22 ' Memoircs de l'Acad. des Sciences de St. Fetersbourg,' torn. x. No. 15, 1806. 198 THE DESCENT OF MAN. [Part I. class of Ascidians, the other rising to the crown and summit of the animal kingdom by giving birth to the Vertebrata. We have thus far endeavored 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 appearance in him through rever- sion, 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 hair, both sexes having beards ; their ears were jointed 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 now only occasionally reappear, but are normally present in the Quadrumana. The great artery and nerve of the hu- merus 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 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 membrane. At a still earlier period the progenitors of man must have been aquatic in their habits ; for morphology plainly tells us that our lungs consist of a modified swim-bladder, which Chap. VI.] AFFINITIES AND GENEALOGY. 199 once served as a float. The clefts on the neck in the embryo of man show where the branchiae once existed. At about this period the true kidneys were replaced by the corpora wolffiana. The heart existed as a simple pulsating vessel ; and the chorda dorsalis took the place of a vertebral col- umn. These early predecessors of man, thus seen in the dim recesses of time, must have been as lowly organized as the lancelet or amphioxus, or even still more lowly or- ganized. There is one other point deserving a fuller notice. It has long been known that in the vertebrate kingdom one sex bears rudiments of various accessory parts, appertain- ing to the reproductive system, which properly belong to the opposite sex ; and it has now been ascertained that at a very early embryonic period both sexes possess true male and female glands. Hence some extremely remote progenitor of the whole vertebrate kingdom appears to have been hermaphrodite or androgynous.23 But here we encounter a singular difficulty. In the mammalian class the males possess in their vesiculre prostatica rudiments of a uterus with the adjacent passage ; they bear also rudiments of mamma?, and some male marsupials have rudiments of a marsupial sack.24 Other analogous facts could be added. Are we, then, to suppose that some ex- tremely ancient mammal possessed organs proper to both sexes, that is, continued androgynous after it had acquired 23 This is the conclusion of one of the highest authorities in com- parative anatomy, namely, Prof. Gegenbaur : ' Grundziige der vergleich. Anat.' 1870, s. 876. The result has been arrived at chiefly from the study of the Amphibia ; but it appears from the researches of YValdcyer (as quoted in Humphry's c Journal of Anat. and Phys.' 1869, p. 161), that the sexual organs of even " the higher vertebrata are, in their early condition, hermaphrodite." Similar views have long been held by some authors, though until recently not well based. 24 The male Thylacinus offers the best instance. Owen, ' Anatomy of Vertebrates,' vol. hi. p. '111. 200 THE DESCENT OF MAN. [Part L 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 fishes 28 and amphibians, would still have remained androgynous. We must, on the contrary, believe that when the fire ver- tebrate classes diverged from their common progenitor the sexes had already become separated. To account, how- ever, for male mammals possessing rudiments of the accesso- ry female organs, and for female mammals possessing rudi- ments 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 possi- ble that, as the one sex gradually acquired the accessory or- gans proper to it, some of the successive steps or modifi- cations 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, and brilliant colors, acquired by male birds for battle or ornament, and transferred to the fe- males in an imperfect or rudimentary condition. The possession by male mammals of functionally im- perfect mammary organs is, in some respects, especially curious. The Monotremata have the proper milk-secret- ing glands with orifices, but no nipples ; and, as these animals stand at the very base of the mammalian series, it is probable that the progenitors of the class possessed, in like manner, the milk-secreting glands, but no nipples. This conclusion is supported by what is known of their 25 Serranus is well known often to be in an hermaphrodite condition ; but Dr. Giinther informs me that he is convinced that this is not its nor- mal state. Descent from an ancient androgynous prototype would, how- ever, naturally favor and explain, to a certain extent, the recurrence of this condition in these fishes. Chap. VI.] AFFINITIES AND GENEALOGY. 201 manner of development ; for Professor Turner informs me, on the authority of Kolliker and Lauger, that in the em- bryo the mammary glands can be distinctly traced before the nipples are in the least visible ; and it should be borne in mind that the development of successive parts in tht individual generally seems to represent and accord with the development of successive beings in the same line of descent. The Marsupials differ from the Monotremata by possessing nipples ; so that these organs were probably first acquired by the Marsupials after they had diverged from, and risen above, the Monotremata, and were then trans- mitted to the placental mammals. ~No one will suppose that after the Marsupials had approximately acquired their present structure, and therefore at a rather late pe- riod in the development of the mammalian series, any of its members still remained androgynous. "We seem, there- fore, compelled to recur to the foregoing view, and to con- clude that the nipples were first developed in the females of some very early marsupial form, and were then, in ac- cordance with a common law of inheritance, transferred in a functionally imperfect condition to the males. Nevertheless, a suspicion has sometimes crossed my mind that long after the progenitors of the whole mam- malian 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 marsupial sacks. This will not appear utterly incredible, if we reflect that the males of syngnathous fishes receive the eggs of the females in their abdominal pouches, hatch them, and afterward, as some believe, nourish the young;26 that certain other 20 Mr. Lockwood believes (as quoted in ' Quart. Journal of Science,' April, 18G8, p. 269), from what he has observed of the development of Hippocampus, that the walls of the abdominal pouch of the male in some way afford nourishment. On male fishes hatching the ova in their 202 THE DESCENT OF MAN. [Part L male fishes hatch the eggs within their mouths or bran- chial cavities ; that certain male toads take the chaplets of eunainc,' 1861, p. 128) has collected much evidence on this head. 238 THE DESCENT OF MAN. [Part I. inhabitants of tropical America, are wholly different from the Negroes who inhabit the opposite shores of the At- lantic, 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 accounted for, except 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 constantly use certain sense-organs have the cavities in which thev are lodged somewhat increased in size, and their features con- sequently a little modified. With civilized nations, the reduced size of the jaws from lessened use, the habitual play of different muscles serving to express different emo- tions, and the increased size of the brain from greater in- tellectual activity, have together produced a considerable effect on their general appearance, in comparison with savages.52 It is also possible that increased bodily stature, with no corresponding increase in the size of the brain, may have given to some races (judging from the pre- viously adduced cases of the rabbits) an 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-projecting supra-orbital ridges. It is not improbable that the texture of the hair, which differs much in the different races, may stand in some kind of correlation with the structure of the skin ; for the color of the hair and skin are certainly correlated, as is its color and texture with the Mandans.63 52 See Prof. Schaaffhausen, translat. in 'Anthropological Review,' Oct. 1868, p. 429. 53 Mr. Catlin states (' North American Indians,' 3d edit. 1842, vol. i. p. 49) that, in the whole tribe of the Mandans, about one in ten or twelve Chap. VII.] THE KACES OF MAN. 239 The color of the skin and the odor emitted by it are like- wise in some manner connected. With the breeds of sheej) the number of hairs within a given space and the number of the excretory pores stand in some relation to each other." If we may judge from the analogy of our domesticated animals, many modifications of structure in man probably 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 conditions 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 pre- served 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 be thus preserved ; and as far as we are enabled to judge (although always liable to error on this head) not one of the external differences between the races of man are of any direct or special service to him. The intellectual and moral or social faculties must of course be excepted from this remark ; but differences in these faculties can have had little or no influence on external characters. The variability of all the characteristic differences between the races, before referred to, likewise indicates that these differences cannot be of much importance ; for, had they of the members of all ages and both sexes have bright silvery gray hair, which is hereditary. Now this hair is as coarse and harsh as that of a horse's mane, while the hair of other colors is fine and soft. 54 On the odor of the skin, Godron, 'Sur l'Espece,' torn. ii. p. 217. On the pores in the skin, Dr. Wilckens, ' Die Aufgaben der landwirth. Zootechnik,' 1869, s. 1. 240 THE DESCENT OF MAN. [Part I. been important, they would long ago have been either fixed and preserved, or eliminated. In this respect man resembles those forms, called by naturalists protean or polymorphic, which have remained extremely variable, owing, as it seems, to their variations being of an indif- ferent, nature, and consequently to their having escaped the action of natural selection. We have thus far been baffled in all our attempts to account for the differences between the races of man; but there remains one important agency, namely, Sexual Selec- tion, which appears to have acted as powerfully on man as on many other animals. I do not intend to assert that sexual selection will account for all the differences be- tween the races. An unexplained residuum is left, about which we can in our ignorance only say that, as individ- uals are continually born with, for instance, heads a little rounder or narrower, and with noses a little longer or shorter, such slight differences might become fixed and uniform, if the unknown agencies which induced them were to act in a more constant manner, aided by long-con- tinued intercrossing. Such modifications come under the provisional class, alluded to in our fourth chapter, which for the want of a better term have been called sponta- neous variations. Nor do I pretend that the effects of sexual selection can be indicated with scientific precision ; but it can be shown that it would be an inexplicable fact if man had not been modified by this agency, which has acted so powerfully on innumerable animals, both high and low in the scale. It can further be shown that the differences between the races of man, as in color, hairi- ness, form of features, etc., 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- Chap. VII.] THE RACES OF MAN. 241 voted to it the Second Part of this work. At the close I shall return to man, and, after attempting to show how far he has been modified through sexual selection, will give a brief summary of the chapters in this First Part. PAKT II. SEXUAL SELECTION. 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. — Variahility of the Male. — Choice exerted hy the Female. — Sexual compared with Natural Selection. — Inheritance, at Corresponding Periods of Life, at Corresponding Seasons of the Year, and as limited hy Sex. — Eelations 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 Limitation of the Numbers of the two Sexes through Natural Selection. With animals which have their sexes separated, the males necessarily differ from the females in their organs of reproduction ; and these afford the primary sexual char- acters. But the sexes often differ in what Hunter has called secondary sexual characters, which are not directly connected with the act of reproduction ; for instance, in the male possessing certain organs of sense or locomotion, of which the female is quite destitute, or in having them more highly developed, in order 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 kinds graduate into, and in some cases can hardly be distinguished from, those which 246 THE PRINCIPLES OF [Part II. are commonly ranked as primary, such as the complex ap- pendages at the apex of the abdomen in male insects. Unless indeed we confine the term " primary " to the re- productive glands, it is scarcely, possible to decide, as far as the organs of prehension are concerned, which ought to be called primary and which secondary. The female often differs from the male in having or- gans for the nourishment or protection of her young, as the mammary glands of mammals, and the abdominal sacks of the marsupials. The male, also, in some few cases differs from the female in possessing analogous or- gans, as the receptacles for the ova possessed by the males of certain fishes, and those temporarily developed in certain male frogs. Female bees have a special appa- ratus for collecting and carrying pollen, and their oviposi- tor is modified into a sting for the defence of their larva? 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 be given, but they do not here concern us. There are, however, other sexual differences quite disconnected with the primary organs with which we are more especially concerned — such as the greater size, strength, and pug- nacity of the male, his weapons of offence or means of defence against rivals, his gaudy coloring and various ornaments, his power of song, and other such charac- ters. Besides the foregoing primary and secondary sexual differences, the male and female sometimes differ in struct- ures connected with different habits of life, and not at all, or only indirectly, related to the reproductive functions. Thus the females of certain flies (Culicidse and Tabanidse) are blood-suckers, while the males live on flowers and have their mouths destitute of mandibles.1 The males 1 Westwood, 'Modern Class, of Insects,' vol. ii. 1840, p. 541. In Chap. VIII.] SEXUAL SELECTION. 247 alone of certain moths and of some crustaceans (e. g., Ta- nais) have imperfect, closed mouths, and cannot feed. The complemental males of certain Oirripedes 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 which has been modified and has lost certain important organs, which the other mem- bers of the same group possess. In other cases it is the female which has lost such parts ; for instance, the female glowworm 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 some weevil-beetles (Curculionidae) there is a great difference between the male and female in the length of the rostrum or snout;2 but the meaning of this, and of many analogous differences, is not at all understood. Differences of structure between the two sexes in relation to different habits of life are generally confined to the lower animals ; but with some few birds the beak of the male differs from that of the female. No doubt in most, but apparently not in all these cases, the differences are indirectly connected with the propagation of the species : thus a female which has to nourish a multitude of ova will require more food than the male, and consequently will require special means for procuring it. A male ani- mal which lived for a very short time might without det- riment lose through disuse its organs for procuring food ; but he* would retain his locomotive organs in a perfect state, so that he might reach the female. The female, on the other hand, might safely lose"* her organs for flying, swimming, or walking, if she gradually acquired habits which rendered such powers useless. regard to the statement about Tanais, mentioned below, I am indebted to Fritz Muller. 2 Kirby and Spencc, ' Introduction to Entomology,' vol. iii. 1826, p. 309. 248 THE PRINCIPLES OF [Part II. We are, however, here concerned only with that kind of selection which I have called sexual selection. This depends on the advantage which certain individuals have over other individuals of the same sex and species, in ex- clusive 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 inher- itance limited to one and the same sex. So, again, the primary sexual organs, and those for nourishing or pro- tecting the young, come under this same head ; for those individuals which generated or nourished their offspring best, would leave, cceteris paribus, the greatest number to inherit their superiority ; while 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 organs of sense and locomotion, but if these organs are necessary for the other purposes of life, as is generally the case, they will have been developed through natural selection. When the male has found the female he sometimes absolutely requires prehensile organs to hold her ; thus Dr. Wallace informs me that the males of certain moths cannot unite with the females if their tarsi or feet are broken. The males of many oceanic crustaceans have their legs and antennse modified in an extraordinary manner for the pre- hension of the female ; hence 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 their kind, and if so their development will have been the result of ordinary or natural selection. When the two sexes follow exactly the same habits of life, and the male has more highly-developed sense or locomotive organs than the female, it may be that these in their perfected state are indispensable to the male for Chap. VIII.] SEXUAL SELECTION. 240 finding the female ; but in the vast majority of cases, they serve only to give one male an advantage over another, for the less well-endowed males, if time were allowed them, would succeed in pairing with the females; and they would in all other respects, judging from the structure of the female, be equally well adapted for their ordinary habits of life. In such cases sexual selection must have come into action, for the males have acquired their pres- ent structure, not from being better fitted to survive in the struggle for existence, but from having gained an ad- vantage over other males, and from having transmitted this advantage to their male offspring alone. It was the importance of this distinction which led me to designate this form of selection as sexual selection. So, again, if the chief service rendered to the male by his prehensile organs is to prevent the escape of the female before the arrival of other males, or when assaulted by them, these organs will have been perfected through sexual selection, that is, by the advantage acquired by certain males over their rivals. But in most cases it is scarcely possible to distin- guish between the effects of natural and sexual selection. Whole chapters could easily be filled with details on the differences between the sexes in their sensory, locomotive, and prehensile organs. As, however, these structures are not more interesting than others adapted for the ordinary purposes of life, I shall almost pass them over, giving only a few instances under each class. There are many other structures and instincts which must have been developed through sexual selection — such as the weapons of offence and the means of defence pos- sessed by the males for fighting with and driving away their rivals — their courage and pugnacity — their orna- ments of many kinds — their organs for producing vocal or instrumental music — and their glands for emitting odors ; most of these latter structures serving only to al- 250 THE PRINCIPLES OF [Part II. lure or excite the female. That these characters are the result of sexual and not of ordinary selection is clear, as unarmed, unornamented, or unattractive males would suc- ceed equally well in the battle for life 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 sex- ual characters of the kind just referred to, will be fully discussed in the following chapters, as they are in many respects interesting, but more especially as they depend on the will, choice, and rivalry of the individuals of either sex. When we behold two males fighting for the posses- sion of the female ; or several male birds displaying their gorgeous plumage, and performing the strangest antics before an assembled body of females, wq 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 of variability, if it led to some advantage, however slight, would suffice for the work of sexual selection ; and it is certain that secondary sexual characters 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 — so 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 im- Chap. VIIL] SEXUAL SELECTION. 251 plies powers of discrimination and taste on the part of the female which will at first appear extremely improbable ; but I hope hereafter to show that this is not the case. From our ignorance on several points, the precise man- ner in which sexual selection acts is to a certain extent uncertain. Nevertheless if those naturalists who already believe in the mutability of species, will read the following chapters, they will, I think, agree with me that sexual se- lection has played an important part in the history of the organic world. It is certain that with almost all animals there is a struggle between the males for the possession of the female. This fact is so notorious that it would be su- perfluous to give instances. Hence the females, supposing that their mental capacity sufficed for the exertion of a choice, could select one out of several males. But in nu- merous cases it appears as if it had been specially arranged that there should be a struggle between many males. Thus with migratory birds, the males generally arrive be- fore the females at their place of breeding, so that many males are ready to contend for each female. The bird- catchers assert that this is invariably the case with the nightingale and blackcap, as I am informed by Mr. Jenner Weir, who confirms the statement with respect to the lat- ter species. Mr. Swaysland, of Brighton, who has been in the habit, during the last forty years, of catching our migratory birds on their first arrival, writes to me that he has never known the females of any species to arrive before their males. During one spring he shot thirty-nine males of Kay's wagtail {JBudytes JRaii) before he saw a single fe- male. Mr. Gould has ascertained by dissection, as he in- forms me, that male snipes arrive in this country before the females. 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 252 TIIE PRINCIPLES OF [Part II. 'with frogs and toads. Throughout the great class of in- sects 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.3 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 constitu- tions. On the whole, there can be no doubt that with al- most all animals, in which the sexes are separate, there is a constantly recurrent struggle between the males for the possession of the females. Our difficulty in regard to sexual selection lies in un- derstanding how it is that the males which conquer other males, or those which prove the most attractive to the fe- males, leave a greater number of offspring to inherit their superiority than the beaten and less attractive males. Unless this result followed, the characters which gave to certain males an advantage over others, could not be per- fected and augmented through sexual selection. When the sexes exist in exactly equal numbers, the worst-endowed males will ultimately find females (excepting where polyg- amy prevails), and leave as many offspring, equally well fitted for their general habits of life, as the best-endowed males. From various facts and considerations, I former- ly inferred that with most animals, in which secondary 3 Even with those of plants in which the sexes are separate, the male Qowers are generally mature before the female. Many hermaphrodite plants are, as first shown by C. K. Sprengel, dichogamous ; that is, their male and female organs are not ready at the same time, so that they can- hot be self-fertilized. Now with such plants the pollen is generally ma- ture in the same flower before the stigma, though there are some excep- tional species in which the female organs are mature before the male. Ciiai*. VIII.] SEXUAL SELECTION. 253 sexual characters were well developed, the males considera- bly exceeded the females in number ; and this does hold good 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 bet- ter-armed or more attractive males would leave the lar- gest number of offspring. But after investigating, as far as possible, the numerical proportions 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 di- vide the females inhabiting a district into two equal bodies : the one consisting of the more vigorous and bet- ter-nourished individuals, and the other of the less vigor- ous 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 Weir, who has dur- ing many years carefully attended to the habits of 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 be- fore the females ; of the males the 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 females, 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 numeri- cally 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 cour- age of the males, or to improve their weapons. But in a multitude of cases the males which conquer 254 TIIE PRINCIPLES OF [Part II. other males do not obtain possession of the females, in- dependently 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 ex- cited 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 pairs would have the same advantage in rearing offspring on the female side as above explained, and nearly the same advantage on the male side. And this apparently has sufficed during a long course of generations to add not only to the strength and fighting-powers of the males, but likewise to their various ornaments or other attractions. In the converse and much rarer case of the males se- lecting 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 es- pecially 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 pre- ferred and selected certain individuals of the opposite sex ; 4 I have received information, hereafter to be given, to this effect with respect to poultry. Even with birds, such as pigeons, which pair for life, the female, as I hear from Mr. Jenner Weir, will desert her mate if he ia injured or grows weak. Chap. VIII.] SEXUAL SELECTION. 255 supposing that they selected not only the more attractive, but likewise the more vigorous individuals. Numerical Proportion of the Two Sexes. — I have re- marked that sexual selection would be a simple affair if ' the males considerably exceeded in number the females. Hence I was led to investigate, as far as I could, the pro- portions between the two sexes of as many animals as possible ; but the materials are scanty. I will here give only a brief abstract of the results, retaining the details for a supplementary discussion, so as not to interfere with the course of my argument. Domesticated animals alone afford the opportunity of ascertaining the proportional numbers at birth ; but no records have been specially kept for this purpose. By indirect means, however, I have col- lected a considerable body of statistical data, from which it appears that with most of our domestic animals the sexes are nearly equal at birth. Thus with race-horses, 25,500 births have been recorded during twenty-one years, and the male births have been to the female births as 99.7 to 100. With greyhounds the inequality is greater than with any other animal, for during twelve years, out of G,878 births, the male births have been as 110.1 to 100 female births. It ie, however, in some degree doubtful whether it is safe to infer that the same proportional num- bers 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, in Russia as 108.9,^and with the Jews of Livonia as 120 to 100 females. The proportion is also mysteriously affected by the circumstance of the births being legitimate or illegitimate. For our present purpose we are concerned with the proportion of the sexes, not at birth, but at maturity, and 250 THE PRINCIPLES OF [Part II. tins adds another element of doubt ; for it is a well-ascer- tained fact that with man a considerably larger proportion of males than of females die before or dining birth, and during the first few years of infancy. So it almost cer- tainly 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. They must, also, while 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 be- lieved often to be devoured by the latter or by other fishes. With some birds the females appear to die in larger pro- portion than the males : they are also liable to be de- stroyed on their nests, or while in charge of their young. With insects the female larvae are often larger than those of the males, and would consequently be more likely to be devoured: in some cases the mature . females are less active and less rapid in their movements than the males, and 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 when the inequality is strongly marked, is but little trustworthy. Nevertheless, as far as a judgment can be formed, we may conclude, from the facts given in the supplement, that the males of some few mammals, of many birds, of some fish and insects, considerably exceed in number the females. The proportion between the sexes fluctuates slightly during successive years : thus with race-horses, for every 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 through- out a more extensive area than England, these fluctuations would probably have disappeared ; and such as they are, Chap. VIII.] SEXUAL SELECTION. 257 they would hardly suffice to lead under a state of nature to the effective action of sexual selection. Nevertheless with some few wild animals, the proportions seem, as shown in the supplement, to fluctuate either during differ- ent seasons or in different localities in a sufficient decree to lead to such action. For 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, or were the most attractive to the females, would probably be transmitted to the offspring and would not subsequently be eliminated. During the succeeding sea- sons, when from the equality of the sexes every male was everywhere able to procure a female, the stronger or more attractive males previously produced would still have at least as good a chance of leaving offspring as the less strong or less attractive. Polygamy. — The practice of polygamy leads to the same results as would follow from an actual inequality in the number of the sexes ; for if each male secures two or more females, many males will not be able to pair; and the latter assuredly will be the weaker or less attractive individuals. Many mammals and some few birds are polygamous, but with animals belonging to the lower classes I have found no evidence of this habit. The intel- lectual powers of such animals are, perhaps, not sufficient to lead them to collect and guard a harem of females. That some relation exists between polygamy and the de- velopment of secondary sexual characters, appears nearly certain ; and this Supports the view that a numerical pre- ponderance of males would be ejninently favorable to the action of sexual selection. Nevertheless many animals, especially birds, which are strictly monogamous, display strongly-marked secondary sexual characters ; while some few animals, which are polygamous, are not thus charac- terized. 1 *-i 258 THE PRINCIPLES OF [Part II. We will first briefly run through the class of mammals, and then turn to birds. The gorilla seems to be a polyg- amist, and the male differs considerably from the female ; so it is with some baboons which live in herds containing twice as many adult females as males. In South America the 3fycetes caraya presents well-marked sexual differ- ences in color, beard, and vocal organs, and the male gen- erally lives with two or three wives: the male of the Cebus capucinus differs somewhat from the female, and appears to be polygamous.5 Little is known on this head with respect to most other monkeys, but some species are strictly monogamous. The ruminants are eminently polyg- amous, and they more frequently present sexual differ- ences than almost any other group of mammals, especially in their weapons, but likewise in other characters. Most deer, cattle, and sheep, are polygamous ; as are most ante- lopes, though some of the latter are monogamous. Sir Andrew Smith, in speaking of the antelopes of South Africa, says that in herds of about a dozen there was rarely more than one mature male. The Asiatic Ant Hope saiga appears to be the most inordinate polygamist in the world ; for Pallas 6 states that the male drives away all rivals, and collects a herd of about a hundred, consisting of females and kids : the female is hornless and has softer hair, but does not otherwise differ much from the male. The horse is polygamous, but, except in his greater size and in the proportions of his body, differs but little from 5 On the Gorilla, Savage and Wyman, c Boston Journal of Nat. Hist.' vol. v. 1845-1847, p. 423. On Cynocephalus, Brehm, 'Illust. Thierleben,' B. i. 1864, s. 77. On Mycetes. Rengger, ' Naturgesch. : Saugethiere von Paraguay,' 1830, s. 14, 20. On Cebus, Brehm, ibid. s. 108. 6 Pallas, * Spicilegia Zoolog., Fasc. xii. 1777, p. 29. Sir Andrew- Smith, 'Illustrations of the Zoology of South Africa,' 1849, pi. 29, on the Kobus. Owen, in his 'Anatomy of Vertebrates ' (vol. iii. 1868, p. 633), gives a table incidentally showing which species of Antelopes pair and which are gregarious. Chap VIII.] SEXUAL SELECTION. 259 the mare. The wild-boar, in his great tusks and some other characters, presents well-marked sexual characters ; in Europe and in India he leads a solitary life, except dur- ing the breeding-season ; but at this season he consorts in India with several females, as Sir W. Elliot, who has had large experience in observing this animal, believes : whether this holds good in Europe is doubtful, but is sup- ported by some statements. The adult male Indian ele- phant, like the boar, 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 smaller and weaker ones. The male differs from the fe- male by his immense tusks and greater size, strength, and endurance ; so great is the difference in these latter re- spects, that the males when caught are valued at twenty per cent, above the females.7 With other pachydermatous animals the sexes differ very little or not at all, and they are not, as far as known, polygamists. Hardly a single species among the Cheiroptera and Edentata, or in the great Orders of the Rodents and Insectivora, presents well-developed secondary sexual differences; and I can find no account of any species being polygamous, except- ing, 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 gener- ally with more than one, and, in one case, was found with as many as five females, so that he is polygamous. He is, as far as I can discover, the sole polygamist in the whole group of the terrestrial Carnivora, and he alone presents well-marked sexual characters. If, however, we turn to 7 Dr. Campbell, in ' Proc. Zoolog. Soc.' 1869, p. 138. See also an interesting paper, by Lieut. Johnstone, in ' Proc. Asiatic Soc. of Bengal/ May, 1868 2G0 THE PRINCIPLES OF [Part II. the marine Carnivora, the case is widely different ; for many species of seals offer, as we shall hereafter see,, ex- traordinary sexual differences, and they are eminently polygamous. Thus the male sea-elephant of the Southern Ocean always possesses, according to Peron, several fe- males, and the sea-lion of Forster is said to he surrounded by from twenty to thirty females. In the North, the male sea-bear of Steller is accompanied by even a greater number of females. With respect to birds, many species, the sexes of 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 fe- male, with the common blackbird, and with the bullfinch, which is said to pair for life. So it is, as I am informed by Mr. Wallace, with the Chatterers or Cotingida? of South America, and numerous other birds. In several groups I have not been able to discover whether the species are polygamous or monogamous. Lesson says that birds of paradise, so remarkable for their sexual differences, are polygamous, but Mr. Wallace doubts whether he had suf- ficient evidence. Mr. Salvin informs me that he has been led to believe that humming-birds are polygamous. The male widow-bird, remarkable for his caudal plumes, cer- tainly seems to be a polygamist.8 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 Gallinacese present almost as strongly-marked sexual differences as birds of paradise or humming-birds, 8 ' The Ibis,' vol. iii. 1861, p. 133, on the Progne Widow-bird. See also on tbe Vidua axillaris, ibid. vol. ii. 1860, p. 211. On the polygamy of the Capercailzie and Great Bustard, see L. Lloyd, ' Game Birds of Sweden,' 1867, pp. 19, 128. Montagu and Selby speak of the Black Grouse as polygamous, and of the Tted Grouse as monogamous. Chap. VIII.] SEXUAL SELECTION. 2G1 and many of the species are, as is well known, polyga- mous ; others being strictly monogamous. What a con- trast is presented between the sexes by the polygamous peacock or pheasant, and the monogamous guinea-fowl or partridge ! Many similar cases could be given, as in the grouse-tribe, in which the males of the polygamous capercailzie and black-cock differ greatly from the fe- males; while the sexes of the monogamous red grouse and ptarmigan differ very little. Among the Cursores, no great number of species offer strongly-marked sexual differences, except the bustards, and the great bustard ( Otis tarda) is said to be polygamous. With the Gralla- tores, extremely few species differ sexually, but the ruff (Machetes pugnax) affords a strong exception, and this species is believed by Montagu to be a polygamist. Hence it appears that with birds there often exists a close rela- tion between polygamy and the development of strongly- marked sexual differences. On asking Mr. Bartlett, at the Zoological Gardens, who has had such large experi- ence with birds, whether the male tragopan (one of the Gallinacea?) was polygamous, I was struck by his answer- ing, " I do not know, but should think so from his splen- did colors." It deserves notice that the instinct of pairing with a single female is easily lost under domestication. The wild-duck is strictly monogamous, the domestic duck highly polygamous. The Rev. W. D. Fox informs me that with some half-tamed wild-ducks, kept on a large pond in his neighborhood, so many mallards were shot by the gamekeeper that only one was left for every seven or eight females ; yet unusually large broods were reared. The guinea-fowl is strictly monogamous ; but Mr. Fox finds that his birds succeed best when he keeps one cock to two or three hens.9 Canary-birds pair in a state of na- 9 The Rev. E. S. Dixon, however, speaks positively (' Ornamental 262 THE PRINCIPLES OF [Part II. ture, but the breeders in England successfully put one male to four or five females ; nevertheless 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 degree probable that monogamous spe- cies, in a state of nature, might readily become either tem- porarily or permanently polygamous. 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 ; lb and the male during the breeding-season differs conspicuously from the female. To sum up on the means through which, as far as we can judge, sexual selection has led to the development of secondary sexual characters. It has been shown that the largest number of vigorous offspring will be reared 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 if the more vigorous males select the more attractive and at the same time healthy and vigorous fe- males ; and this will especially hold good if the male de- fends the female, and aids in providing food for the young. The advantage thus gained by the more vigorous pairs in rearing a larger number of offspring has apparently suf- ficed to render sexual selection efficient. But a large pre- ponderance in number of the males over the females would Poultry,' 1848, p. 76) about the eggs of the guinea-fowl being infer tilo when more than one female is kept with the same male. 10 Noel Humphreys, ' River Gardens,' 1857. Chap. VIIL] SEXUAL SELECTION. 263 be still more efficient ; whether the prei3onderance was only occasional and local, or permanent ; whether it oc- curred at birth, or subsequently from the greater destruc- tion of the females ; or whether it indirectly followed from the practice of polygamy. The Male generally more modified than the Female. — Throughout the animal kingdom, when the sexes differ from each other in external appearanee, it is the male which, with rare exceptions, has been chiefly modified ; for the female still remains more like the young of her own 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 fe- males. Hence it is the males that fight together and sedu- lously 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 shall seek the female." With spiders and crustaceans, as I hear from two great authorities, Mr. Blackwall and Mr. C. Spence Bate, the males are more active and more erratic in their habits than the females. With insects and crus- taceans, when the organs of sense or locomotion are pros- 11 Kirby and Spence, 'Introduction to Entomology,' vol. iii. 1826, p. 342. 264 THE PRINCIPLES OF [Part II. ent in the one sex and absent in the other, or when, as is frequently the case, 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 devoloped ; and this shows that the male is the more active member in the courtship of the sexes.12 The female, on the other hand, with the rarest excep- tion, is less eager than the male. As the illustrious Hun- ter 13 long ago observed, she generally " requires to be courted ; " she is coy, and may often be seen endeavoring for a long time to escape from the male. Every one who has attended to the habits of animals will be able to call to mind instances of this kind. Judging from various facts, hereafter to be given, and from the results which may fairly be attributed to sexual selection, the female, though comparatively passive, generally exerts some choice and accepts one male in preference to others. Or she may accept, as appearances would sometimes lead us to believe, not the male which is the most attractive to her, but the one which is the least distasteful. The ex- ertion of some choice on the part of the female seems almost .as general a law as the eagerness of the male. We are naturally led to inquire why the male in so many and such widely-distinct classes has been rendered more easrer than the female, so that he searches for her and plays the more active part in courtship. It would be 12 One parasitic Hymenopterous insect (Westwood, ' Modern Class, of Insects,' vol. ii. p. 160) forms an exception to the rule, as the male has rudimentary wings, and never quits the cell in which it is born, while the female has well-developed wings. Audouin believes that the females are impregnated by the males which are born in the same cells with them ; but it is much more probable that the females visit other cells, and thus avoid close interbreeding. We shall hereafter meet with a few exceptional cases, in various classes, in which the female, instead of the male, is the seeker and wooer. 13 ' Essays and Observations,' edited by Owen, vol. i. 1861, p. 194. Chap. VIII.] SEXUAL SELECTION. 265 no advantage and some loss of power if both sexes were mutually to search for each other ; but why should the male almost always be the seeker? With plants, the ovules after fertilization have to be nourished for a time ; hence the pollen is necessarily brought to the female or- gans— being placed on the stigma, through the agency of insects or of the wind, or by the spontaneous movements of the stamens ; and with the Alga?, etc., by the locomo- tive power of the antherozooids. "With lowly-organized animals permanently 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 ; for the ova, e'ven if detached before being fertilized 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. In the case of animals not affixed to the same spot, but enclosed within a shell with no power of protruding any part of their bodies, and in the case of animals having little power of locomotion, the males must trust the fertilizing element to the risk of at least a short transit through the waters of the sea. It would, therefore, be a great advan- tage to such animals, as their organization became per- fected, if the males when ready to emit the fertilizing ele- ment, were to acquire the habit of approaching the female as closely as possible. The males of various lowly-organ- ized animals having thus aboriginally acquired the habit of approaching and seeking the females, the same habit would naturally be transmitted- to their more highly-de- veloped male descendants; and in order that they should 14 Prof. Sachs ('Lekrbucli dcr Botanik,' 1870, s. G33) in speaking of the male and female reproductive cells, remarks : " Verhiilt sick die eine bei dcr Vereinigung activ, .... die andere erscheint bei der V«reiui- gung passiv." 266 THE PRINCIPLES OF [Part II. become efficient seekers, they would have to be endowed with strong passions. The acquirement of 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 led to the much more frequent development of secondary sexual characters in the male than in the female. But the development of such characters will have been much aided, if the conclusion at which I arrived, after studying domesticated animals, can be trusted, namely, that the male is more liable to vary than the female. I am aware how difficult it is to verify a conclusion of this kind. Some slight evidence, however, can be gained by compar- ing the two sexes in mankind, as man has been more care- fully observed than any other animal. During the No- vara Expedition 15 a vast number of measurements of va- rious parts of the body in different races were made, and the men were found in almost every case to present a greater range of variation than the women ; but I shall have to recur to this subject in a future chapter. Mr. J. Wood,16 who has carefully attended to the variation of the muscles in man, puts in italics the conclusion that " the greatest number of abnormalities in each subject is found in the males." He had previously remarked that " alto- gether in 102 subjects the varieties of redundancy were found to be half as many again as in females, contrasting widely with the greater frequency of deficiency in females before described." Prof. Macalister likewise remarks " 15 'Reise der Novara : Anthropolog. Theil,' 1867, s. 216-269. The results were calculated by Dr. Weisbach from measurements made by Drs. K. Scherzer and Schwarz. On the greater variability of the males of domesticated animals, see my ' Variation of Animals and Plants under Domestication,' vol. ii. 1868, p. 75. 16 'Proceedings Royal Soc.' vol. xvi. July, 1868, pp. 519, 524. 11 'Proc. Royal Irish Academy,' vol. x. 1868, p. 123. Chap. VIII.] SEXUAL SELECTION. 267 that variations in the muscles " are probably more com- mon in males than females." Certain muscles which are not normally present in mankind are also more frequently developed in the male than in the female sex, although exceptions to this rule are said to occur. Dr. Burt Wild- er18 has tabulated the cases of 152 individuals with su- pernumerary digits, of which 86 were males, and 39, or less than half, females ; the remaining 27 being of unknown sex. It should not, however, be overlooked that women would more frequently endeavor to conceal a deformity of this kind than men. Whether the large proportional number of deaths of the male offspring of man and appar- ently of sheep, compared with the female offspring, be- fore, 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 in 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 ac- quired well-pronounced secondary sexual characters, such as brighter colors, greater size, strength, or pugnacity. With birds, as we 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 selecting, as we may infer from the results, the more attractive females. Certain female birds have thus been rendered more highly colored or otherwise ornamented, as well as more powerful and pug1 nacious, than the males, these characters being transmit- ted to the female offspring alone. It may be suggested that in some cases a double pro- cess of selection has been carried on ; the males having 18 'Massachusetts Medical Soc' vol. ii. No. 3, 1808, p. 9. 268 THE TRIXCIPLES OF [Part II. selected the more attractive females, and the latter the more attractive males. This process, however, though it- might lead to the modification of both sexes, would not make the one sex different from the other, unless indeed their taste for the beautiful differed ; but this is a suppo- sition too improbable in the case of any animal, excepting man, to be worth considering. There are, however, many animals, in which the sexes resemble each other, both being furnished with the same ornaments, which analogy would lead us to attribute to the agency of sexual selec- tion. In such cases it may be suggested with more plausibility, that there has been a double or mutual pro- cess of sexual selection ; the more vigorous and precocious females having selected the more attractive and vigorous males, the latter having rejected all except the more at- tractive females. But, from what we know of the habits of animals, this view is hardly probable, the male being generally eager to pair with any female. It is more probable that the ornaments common to both sexes were acquired by one sex, generally the male, and then trans- mitted to the offspring of both sexes. If, indeed, during a lengthened period the males of any species were greatly to exceed the females in number, and then during anothei lengthened period under different conditions the reverse were to occur, a double, but not simultaneous, process of sexual selection might easily be carried on, by which the two sexes might be rendered widely different. We shall hereafter see that many animals exist, of which neither sex is brilliantly colored or provided with special ornaments, and yet the members of both sexes or of one alone have probably been modified through sexual selection. The absence of bright tints or other ornaments may be the result of variations of the right kind never having occurred, or of the animals themselves preferring simple colors, such as plain black or white. Obscure Chap. VIII.] SEXUAL SELECTION. 2G9 eolors have often been acquired through natural selection for the sake of protection, and the acquirement through sexual selection of conspicuous colors, 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 produced unless a larger number of off- spring 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 maimer than natural selection. The latter produces its effects by the life or death at all as;es of the more or less successful individuals. Death, indeed, not rarely ensues from the conflicts of rival males. But generally the less successful male merely fails to obtain a female, or obtains later in the season a retarded and less vigorous female, or, if polyg- amous, obtains fewer females ; so that they leave fewer, or less vigorous, or no offspring. In regard to structures acquired through ordinary or natural selection, there is in most cases, as long as the conditions of life remain the same, a limit to the amount of advantageous modification in relation to certain special ends ; but in regard to struct- ures adapted to make one male victorious over another, either in fighting or in charming the female, there is no definite limit to the amount of advantageous modification ; so that as long as the proper variations arise the work of sexual selection will go on. This" circumstance may part- ly account for the frequent and extraordinary amount of variability presented by secondary sexual characters. Nevertheless, natural selection will determine that charac- ters of this kind shall not be acquired by the victorious males, which would be injurious to them in any high 270 THE PRINCIPLES OF [Part II. degree, either by expending too much of their vital powers, or by exposing them to any great danger. The development, however, of certain structures — of the horns, for instance, in certain stags — has been carried to a won- derful extreme ; and in some instances to an extreme which, as far as the general conditions of life are con- cerned, must be slightly injurious to the male. From this fact we learn that the advantages which favored 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 instances more important than the power to conquer other males in battle. LAWS OF INHEPJTANCE. In order to understand how sexual selection has acted, and in the course of ages has produced conspicuous re- sults with many animals of many classes, it is necessary to bear in mind the laws of inheritance, as far as they are known. Two distinct elements are included under the term "inheritance," namely, the transmission and the development of characters ; but as these generally go to- gether, the distinction is often overlooked. We see this distinction in those characters which are transmitted through the early years of life, but are developed only at maturity or during old age. We see the same distinction more clearly wTith secondary sexual characters, for these are transmitted through both sexes, though developed in one alone. That they are present in both sexes, is mani- fest when two species, having strongly-marked sexual characters, are crossed, for each transmits the characters Chap. VIII.] SEXUAL SELECTION. 271 proper to its own male and female sex to the hybrid off- spring of both sexes. The same fact is likewise manifest, when characters proper to the male are occasionally de- veloped in the female when she grows old or becomes diseased ; and so conversely with the male. Again, char- acters 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 are transmitted through two, three, or many generations, and are then under cer- tain unknown favorable conditions developed. This im- portant 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. Ac- cording to this hypothesis, every unit or cell of the body throws off geminules or undeveloped atoms, which are transmitted to the" offspring of both sexes, and are multi- plied by self-division. They may remain undeveloped during the early years of life or during successive genera- tions; their development into units or cells, like those from which they were derived, depending on their affinity for, and union with, other units or cells previously devel- oped in the due order of growth. Inheritance at Corresponding Periods of Life. — This tendency is well established. If a new character appears in an animal while young, whether- it endures, throughout life or lasts only for a time, it will reappear, as a general rule, at the same a^e and in the same manner in the off- spring. If, on the other hand, a new character appears at maturity, or even during old age, it tends to reappear in the offspring at the same advanced age. When deviations 272 THE PRINCIPLES OF [Part II, from this rule occur, the transmitted characters much of- tener appear before than after the corresponding age. As I have discussed this subject at sufficient length in another work,19 I will here merely give two or three instances, for the sake of recalling the subject to the reader's mind. In several breeds of the Fowl, the chickens while covered with down, in their first true plumage, and in their adult plumage, differ greatly from each other, as .well as from their common parent-form, the Gallus bankiva / and these characters are faithfully transmitted by each breed to their offspring at the corresponding period of life. For instance, the chickens of spangled Hamburgs, while covered with down, have a few dark spots on the head and rump, but are not longitudinally striped, as in many 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 or tipped with a dark round spot.20 Hence in this breed variations have occurred and have been transmitted at three distinct periods of life. The Pigeon offers a more remarkable case, because the abori- ginal parent-species does not undergo with advancing age any change of plumage, excepting that at maturity the breast becomes more iridescent ; yet there are breeds which do not acquire their characteristic colors until they have moulted two, three, or four times ; and these modifications of plumage are regularly transmitted. 19 ' The Variation of Animals and Plants under Domestication,' vol. ii. 1868, p. 75. In the last chapter but one, the provisional hypothesis of pangenesis, above alluded to, is fully explained. 20 These facts are given on the high authority of a great breeder, Mr. Tecbay, in Tegetmeier's 'Poultry Book,' 1868, p. 158. On the characters of chickens of different breeds, and on the breeds of the pigeon, alluded to in the above paragraph, see ' Variation of Animals,' etc. vol. i. pp. 160, 249 ; vol ii. p. 77. Chap. VIII.] SEXUAL SELECTION. 273 Inheritance at Corresponding Seasons of the Year. — With animals in a state of nature innumerable instances occur of characters periodically appearing at different sea- sons. We see this with the horns of the stag, and with the fur of arctic animals which becomes thick and white during the winter. Numerous birds acquire bright colors 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-colored during the winter ; and I have observed a similar marked change of color in certain ponies in Eng- land. Although I do not know that this tendency to as- sume a differently-colored coat during different seasons of the year is transmitted, yet it probably is so, as all shades of color are strongly inherited by the horse. Nor is this form of inheritance, as limited by season, more remarkable than inheritance as limited by age or sex. Inheritance as limited by Sex. — The equal transmis- sion of characters to both sexes is the commonest form of inheritance, at least with those animals which do not pre- sent strongly-marked sexual differences, and indeed with many of these. But characters are not rarely transferred exclusively to that sex, in which they first appeared. Ample evidence on this head has been advanced in my work on Variation under Domestication; but a few in- stances may here be given. There are breeds of the sheep and goat, in which the horns of the male differ greatly in shape from those of the female ; and these differences, ac- quired under domestication, are regularly transmitted to 21 ' Novae species Quadrupedum e Glirium ordiue,' 1778, p. 7. On the transmission of color by the horse, see 'Variation of Animals, etc., under Domestication,' vol. i. p. 21. Also vol. ii. p. 71, for a general discussion on Inheritance as limited by Sex. 274 THE PRINCIPLES OF [Paet II. the same sex. With tortoise-shell cats the females alone, as a general rule, are thus colored, the males being rusty- red. With most breeds of the fowl, the characters proper to each sex are transmitted to the same sex alone. So general is this form of transmission that it is an anomaly when we see in certain breeds variations transmitted equal- ly to both sexes. There are also certain sub-breeds of the fowl in which the males can hardly be distinguished from each other, while the females differ considerably in color. With the pigeon the sexes of the parent-species do not differ in any external character; nevertheless in certain domesticated breeds the male is differently colored from the female.22 The wattle in the English Carrier-pigeon and the crop in the Pouter are more highly developed in the male than in the female ; and although these characters have been gained through long-continued selection by man, the difference between the two sexes is wholly due to the form of inheritance which has prevailed ; for it has arisen, not from, but 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 sex alone, and some to both sexes, we find in the different breeds of the same species all gradations between great sexual dissimilarity and complete similarity. Instances have already been given with the breeds of the fowl and pigeon ; and under Nature analogous cases are of fre- quent occurrence. With animals under domestication, but whether under Nature I will not venture to say, one sex may lose characters proper to it, and may thus come to resemble to a certain extent the opposite sex ; for in- stance, the males of some breeds of the fowl have lost 22 Dr. Chapuis, ' Le Pigeon Voyageur Beige,' 18G5, p. 87. Boitard et Corbie, ' Les Pigeons de Voliere,' etc., 1S24, p. 173. Chap. VIII.] SEXUAL SELECTION. 275 their masculine plumes and hackles. On the other hand, the differences between the sexes may be increased under domestication, as with merino sheep, in which the ewes have lost their horns. Again, characters proper to one sex may suddenly appear in the other sex ; as with those sub-breeds of the fowl in which the hens while young ac- quire spurs ; or, as in certain Polish sub-breeds, in which the females, as there is reason to believe, originally ac- quired a crest, and subsequently 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 ; or, if naturally dormant, becoming developed. There is one difficult question which it will be conven- ient to defer to a future chapter ; namely, whether a char- acter, at first developed in both sexes, can be rendered through selection limited in its development to one sex alone. If, for instance, a breeder observed that some of his pigeons (in which species characters are usually trans- ferred in an equal degree to both sexes) varied into pale blue ; could he by long-continued selection make a breed, in which the males alone should be of this tint while the females remained unchanged ? I will here only say that this, though perhaps not impossible, would be extremely difficult ; for the natural result of breeding from the pale- blue males wTould be 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 be the least difficulty in making a breed characterized by the two sexes being of a different color, as indeed has been effected with a Belgian breed, in which the males alone are streaked with black. In a similar manner, if any vari- ation appeared in a female pigeon, which was from the 27G . THE PRINCIPLES OF [Pakt II. first sexually limited in its development, it would be easy to make a breed with the females alone thus character- ized ; but if the variation was not thus originally limited, the process would be extremely difficult, perhaps impos- sible. 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 with certain sub-breeds of the pigeon, black stria?, though transmitted through the female, should be de- veloped in the male alone, while every other character is equally transferred to both sexes. Why, again, with cats, the tortoise-shell color should, with rare exceptions, be developed in the female alone. The very same characters, such as deficient or supernumerary digits, color-blindness, etc., may with mankind be inherited by the males 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.23 Although we are thus ignorant, two rules often hold good, namely, that variations which first appear in either sex at a late period of life, tend to be developed in the same sex alone ; while variations which first appear early in life in either sex tend to be developed in both sexes. I am, however, far from sup- posing that this is the sole determining cause. As I have not elsewhere discussed this subject, and as it has an im- portant bearing on sexual selection, I must here enter into lengthy and somewhat intricate details. It is in itself probable that any character appearing at 23 References are given in my ' Variation of Animals under Domesti- cation,' vol. ii. p. 72. Chap. VIII.] SEXUAL SELECTION. 277 an early age would tend to be inherited equally by both sexes, for the sexes do not differ much in constitution, be- fore 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 geminules (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 de- veloped, than with those of the opposite sex. I was first led to infer that a relation of this kind ex- ists, 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 crustaceans, spiders, and some few insects, namely, certain orthoptera and libellulaB. In all these cases the variations, through the accumulation of which the male acquired his proper masculine characters, must have occurred at a somewhat late period of life ; otherwise the young males would have been similarly characterized ; and conformably with our rule, they are transmitted to and developed' in the adult males alone. When, on the other hand, the adult male closely resem- bles the young of both sexes (these, with rare exceptions, being alike), lie generally resembles the adult female; and in most of these cases the variations through which the young and old acquired their present characters, prob- ably occurred in conformity with our rule during youth. But there is here room for doubt, as characters are some- times transferred to the offspring at an earlier age than that at which they first appeared in the parents, so that the parents may have varied when adult, and have trans- ferred their characters to their offspring while young. 278 THE PRINCIPLES OF [Part II. There are, moreover, many animals, in which the two sexes closely resemble each other, and yet both differ from their young ; and here the characters of the adults must have been acquired late in life ; nevertheless, these characters in apparent contradiction to our rule, are trans- ferred to both sexes. We must Lnot, however, overlook the possibility or even probability of successive variations of the same nature sometimes occurring, under exposure to similar conditions, simultaneously in both sexes at a rather late period of life ; and in this case the variations would be transferred to the offspring of both sexes at a corresponding late age ; and there would be no real con- tradiction to our rule of the variations which occur late in life being transferred exclusively to the sex in which they first appeared. This latter rule seems to hold true more generally than the second rule, namely, that variations which occur in either sex early in life tend to be trans- ferred to both sexes. As it was obviously impossible even to estimate in how large a number of cases throughout the animal kingdom these two propositions hold good, it oc- curred to me to investigate some striking or crucial in- stances, ahd to rely on the result. 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 trans- mitted through the female, and capable of occasional ab- normal 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 had 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 development in that sex alone, in which they first appeared in the progenitor of the whole Family. Now, in seven species, belonging to Chap. VIII.] SEXUAL SELECTION. 279 distinct sections of the family and inhabiting different regions, in which the stags alone bear horns, I find that the horns first appear at periods varying from nine months after birth in the roebuck to ten or twelve 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 inquiries 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 at 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 are pro- vided with horns, while in the greater number both sexes have horns. With respect to the period of development, 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 are horned, and the young of a closely-allied species, viz., the eland (Ant. oreas), in which both sexes are horned. Now in strict conformity with our rule, in the young male koodoo,' al- though arrived at the age of ten months, the horns were remarkably small considering the size ultimately attained by them : while in the young male eland, although only three months old, the horns were already very much larger than in the koodoo. It is also worth notice that in the 24 I am much obliged to Mr. Cupples for having made inquiries for me in regard to the Roebuck and Red Deer of Scotland from Mr. Rob- ertson, the experienced head-forester to the" Marquis of Breadalbane. In regard to Fallow-deer, I am obliged to Mr. Eyton and others for informa- tion. For the Cervus alecs of North America, see ' Land and Water,' 1868, pp. 221 and 254 ; and for the C. Virginianus and strongyloceros of the same continent, see J. D. Caton, in ' Ottawa Acad, of Nat. Sc.' 1868, p. 13. For Cervus Eldi of Pegu, see Lieut. Beavan, 'Proc. Zoolog. Soc.1 1867, p. 762. 230 THE PRINCIPLES OF [Part II. prong-horned antelope,26 in 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 sheep, goats, and cattle, in which the horns are well developed in both sexes, though not quite equal in size, they can be felt, or even seen, at birth, or soon afterward.26 Our rule, however, fails in regard to some breeds of sheep, for instance, merinos, in which the rams alone are horned; for I cannot find on inquiry,27 that 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 being hornless ; while 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 (Crossoptllon aicritum), how- ever, offers a remarkable exception, for both sexes possess 25 Antilocapra Americana. Owen, ' Anatomy of Vertebrates,' vol. iii. p. 627. 26 1 have been assured that the horns of the sheep in North Wales can always be felt, and are sometimes even an inch in length, at birth. With cattle Youatt says (' Cattle,' 1834, p. 2'7'7) that the prominence of the frontal bone penetrates the cutis at birth, and that the horny matter is soon formed over it. 27 1 am greatly indebted to Prof. Victor Carus for having made in- quiries, for me, from the highest authorities, with respect to the merino sheep of Saxony. On the Guinea coast of Africa there is a breed of sheep in which, as with merinos, the rams alone bear horns ; and Mr. Winwood Reade informs me that in the one case observed, a young ram born on February 10th first showed horns on March 6th, so that in this rnstance the development of the horns occurred at a later period of life, conformably with our rule, than in the Welsh sheep, in which both sexes are horned. Chap. VIII.] SEXUAL SELECTION. 281 the fine caudal plumes, the large ear-tufts and the crimson velvet about the head ; and I find on inquiry in the Zo- ological Gardens that all these characters, in accordance with our rule, appear very early in life. The adult male can, however, be distinguished from the adult female by one character, namely, by the presence of spurs ; and conformably with our rule, these do not begin to be de- veloped, as I am assured by Mr. Bartlett, before the age of six months, and even at this age, can hardly be dis- tinguished in the two sexes.28 The male and female Peacock differ conspicuously 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 de- veloped very early in life, long before the other orna- ments which are confined 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, while the curled tail-feathers and other ornaments peculiar to the male are developed later.29 Between such 28 In the common peacock (Pavo cristatus) the male alone possesses spurs, while both sexes of the Java peacock (P. muticus) offer the unu- sual case of being furnished with spurs. Hence I fully expected that in the latter species they would have been developed earlier in life than in the common peacock ; but M. Hegt, of Amsterdam, informs me- that, with young birds of the previous year, belonging to both species, com- pared on April 23, 1869, there was no difference in the development of the spurs. The spurs, however, were as yet represented merely by slight knobs or elevations. I presume that I should have been informed if any difference in the rate of development had subsequently been ob- served. 29 In some other species of the Duck Family the speculum in the two sexes differs in a greater degree ; but I have not been able to discover whether its full development occurs later in life in the males of such spe- cies, than in the male of the common duck, as ought to be the case ac- cording to our rule. With the allied Mergus cucullatus we have, however, a case of this kind : the two sexes differ conspicuously in general plu- 13 282 THE PRINCIPLES OF [Part II. extreme cases of close sexual resemblance and wide dis- similarity, as those of the Crossoptilon and peacock, many intermediate ones could be given, in which the characters follow in their order of development our two rules. As most insects emerge from their pupal state in a mature condition, it is doubtful whether the period of de- velopment determines the transference of their characters to one or botli sexes. But we do not know that the col- ored scales, for instance, in two species of butterflies, in one of which the sexes differ in color, while in the other they are alike, are developed at the same relative age in the cocoon. Nor do we know whether all the scales are simultaneously developed on the wings of the same spe- cies of butterfly, in which certain colored marks are con- fined to one sex, while other marks are common to both sexes. A difference of this kind in the period of develop- ment 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 fe- males, and acquire their distinctive 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 domesti- cated animals; first touching on monstrosities and dis- eases. The presence of supernumerary digits, and the mage, and to a considerable degree in the speculum, which is pure white ic the male and grayish-white in the female. Now the young males at ti^st resemble, in all respects, the female, and have a grayish-white spec- trum, but this becomes pure white at an earlier age than that at which the adult male acquires his other more strongly-marked sexual differ- ences in plumage : see Audubon, ' Ornithological Biography,' vol. ill 1885, pp. 249, 250 Chap. VIII.] SEXUAL SELECTION. 283 absence of certain phalanges, must be determined at an early embryonic period — the tendency to profuse bleeding is at least congenital, as is probably color-blindness — yet these peculiarities, and other similar ones, are often limit- ed in their transmission to one sex ; 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 trans- mitted exclusively to the same sex. From the fact of the above abnormal peculiarities becoming attached to one sex, long before the sexual functions are active, we may infer that there must be a difference of some kind 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 any fair conclusion. Gout, however, seems to fall under our rule ; for it is gen- erally caused by intemperance after early youth, and is transmitted from the father to his sons in a much more marked manner than to his daughters. In the various domestic breeds of sheep, goats, and cattle, the mules differ from their respective females in the shape or development of their horns, forehead, mane, dewlap, tail, and hump on the shoulders ; and these pecu- liarities, in accordance with our rule, are not fully devel- oped until rather late in life. With dogs, the sexes do not differ, except that in certain breeds, especially in the Scotch deer-hound, the male is much larger and heavier than the female ; and, as we shall see in a future chapter, the male goes on increasing in size to an unusually late period of life, which will account, according to our rule, for his increased size beinc: transmitted to his male off- spring alone. On the other hand, the tortoise-shell color of the hair, which is confined to female cats, is quite dis- 284 THE PRINCIPLES OF [Part II. tinct at birth, and this case violates our rule. There is a breed of pigeons in which the males alone are streaked with black, and the streaks can be detected even in the nestlings ; but they become more conspicuous at each suc- cessive moult, so that this case partly opposes and partly supports the rule. With the English Carrier and Pouter pigeon the full development of the wattle and the crop occurs rather late in life, and these characters, conform- ably with our rule, are transmitted in full perfection to the males alone. The following cases perhaps come with- in the class previously alluded to, in which the two sexes have varied in the same manner at a rather late period of life, and have consequently transferred their new charac- ters to both sexes at a corresponding late period ; and if so, such cases are not opposed to our rule. Thus there are sub-breeds of the pigeon, described by Neumeister,30 both sexes of which change color after moulting twice or thrice, as does likewise the Almond Tumbler ; neverthe- less 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 color 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 colored in nearly the same manner as their parents, and this renders it proba- 30 'Das Ganze der Taubenzucht,' 183*7, s. 21, 24. For the case of the fitreakcd pigeons, see Dr. Chapuis, 'Le Pigeon Voyageur Beige,' 18G5, p. 87 Chap. VIIL] SEXUAL SELECTION. 285 ble that their colors first appeared early La 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 differ- ently colored. 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 colored 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 Hamburgs, however, offer a partial exception, 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 be- sides color : 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 conse- quence of this it is of unusual size m the adult females. In the Game breeds pugnacity is developed at a wonder- fully 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 ; S1 and in this breed a great bony protuberance 81 For full particulars and references on all these points respecting the several breeds of the Fowl, see ' Variation of Animals and Plants un. 286 THE PRINCIPLES OF [Part II. and an immense crest characterize the adults of both sexes. Finally, from what we have now seen of the relation which exists in many natural species and domesticated races, between the period of the development of their characters and the manner of their transmission — for ex- ample, the striking fact of the early growth of the horns in the reindeer, in which both sexes have horns, in com- parison with their much later growth in the other species in which the male alone bears horns — we may conclude that one cause, though not the sole cause, of characters being exclusively inherited by one sex, is their develop- ment at a late age. And secondly, that one, though ap- parently a less efficient, cause of characters being in- herited by both sexes is their development at an early age, while the sexes differ but little in constitution. It appears, however, that some difference must exist between the sexes even during an early embryonic period, for char- acters 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 be- come developed in the same sex, at the same age, and pe- riodically at the same season of the year, in which they first appeared in the parents. But these laws, from un- known causes, are very liable to change. Hence the suc- cessive 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 der Domestication,' vol. i. pp. 250, 256. In regard to the higher ani- mals, the sexual differences which have arisen under domestication are described in the same work under the head of each species. Chap. VIII.] SEXUAL SELECTION. 287 the laws of inheritance extremely complex, but so are the causes which induce and govern variability. The varia- tions thus caused are preserved and accumulated by sexual selection, which is in itself an extremely complex affair, depending, as it does, on ardor in love, courage, and the rivalry of the males, and on the powers of perception, 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 individu- als of either sex or of both sexes are affected through sexual selection cannot fail to be complex in the highest degree. 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 both sexes at the same age, the young alone are left unmodified. Variations, however, may occur at any period of life in one sex or in both, and be transmitted to both sexes 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 occur under nature. Sexual selection can never act on any animal while young, before 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 have thus be- come provided with weapons for fighting with their rivals, or with organs for discovering and securely holding the female, or for exciting and charming her. When the sexes differ in these respects, it is also, as we have seen, an ex- tremely general law that the adult male differs more or less from the young male ; and we may conclude from this fact that the successive variations, by which the adult male became modified, cannot have occurred much before the age for reproduction. How, then, are we to account 288 THE PRINCIPLES OF [Part II. for this general and remarkable coincidence between the period of variability and that of sexual selection — princi- ples which are quite independent of each other ? I think we can see the cause: it is not that the males have never varied at an early age, but that such variations have com- monly been lost, while those occurring at a later age have been preserved. All animals produce more offspring than can survive to maturity ; and we have every reason to believe that death falls heavily on the weak and inexperienced young. If, then, a certain proportion of the offspring were to vary at birth or soon afterward, in some manner which at this age was of no service to them, the chance of the preser- vation of such variations would be small. We have good evidence under domestication how soon variations of all kinds are lost, if not selected. But variations which oc- curred at or near maturity, and which were of immediate service to either sex, would probably be preserved ; as would similar variations occurring at an earlier period in any individuals which happened to survive. As this prin- ciple has an important bearing on sexual selection, it may be advisable to give an imaginary illustration. We will take a pair of animals, neither very fertile nor the reverse, and assume that after arriving at maturity they live on an average for five years, producing each year five young. They would thus produce 25 offspring ; and it would not, I think, be an unfair estimate to assume that 18 or 20 out of the 25 would perish before maturity, while still young and inexperienced ; the remaining seven or five sufficing to keep up the stock of mature individuals. If so, we can see that variations which occurred during youth, for in- stance, in brightness, and which were not of the least ser- vice to the young, would run a good chance of being utterly lost. While similar variations, which occurring at or near maturity in the comparatively few individuals Chap. VIII.] SEXUAL SELECTION. 289 surviving to this age, and which immediately gave an ad- vantage to certain males, by rendering them more attrac- tive to the females, would be likely to be preserved. No doubt some of the variations in brightness which occurred at an earlier age would by chance be preserved, and eventually give to the male the same advantage as those which appeared later; and this will account for the young males commonly partaking to a certain extent (as may be observed with many birds) of the bright colors of their adult male parents. If only a few of the successive varia- tions in brightness were to occur at a late age, the adult male would be only a little brighter than the young male ; and such cases are common. In this illustration I have assumed that the young varied in a manner which was of no service to them ; but many characters proper to the adult male would be actu- ally injurious to the young — as bright colors from making them conspicuous, or horns of large size from expending much vital force. Such variations in the young would promptly be eliminated through natural selection. With the adult and experienced males, on the other hand, the advantage thus derived in their rivalry with other males would often more than counterbalance exposure to some degree of danger. Thus we can understand how it is that variations which must originally have appeared rather late in life have alone or in chief part been preserved for the development of secondary sexual characters ; and the re- markable coincidence between the periods of variability and of sexual selection is intelligible. As variations which give to .the male an advantage in fio;htin£ with other males, or in finding, securing:, or charm- ing the female, would be of no use to the female, they will not have been preserved in this sex either during youth or maturity. Consequently such variations would be ex- tremely liable to be lost ; and the female, as far as these 290 THE PRINCIPLES OE [Pari tt characters are concerned, would be left unmodified, except- ing in so far as she may have received them by transference from the male. No doubt if the female varied and trans- ferred serviceable characters to her male offspring, these would be favored through sexual selection ; and then both sexes would thus far be modified in the same manner. But I shall hereafter have to recur to these more intricate con- tingencies. In the following chapters, I shall treat of the secondary sexual characters in animals of all classes, and shall en- deavor in each case to apply the principles explained in the present chapter. The lowest classes will detain us for a very short time, but 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 struct- ures by the aid of which the male finds the female, or, when found, 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 be fully 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 attention to the relative numbers of the two sexes throughout the animal kingdom, I will here give such materials as I have been able to collect, although they are extremely imper- fect. They consist in only a few instances of actual enu- meration, and the numbers are not very large. As the proportions are known with certainty on a large scale in the case of man alone, I will first give them, as a standard of comparison. Chap VIII.] SEXUAL SELECTION. 291 Man. — In England during ten years (from 1857 to I860) 707,120 children on an annual average have been born alive, in the proportion of 104.5 males to 100 fe- males. But in 1857 the male births throughout England were as 105.2, and 1865 as 104.0 to 100. Looking to separate districts, in Buckinghamshire (where on an aver- age 5,000 children are annually born) the mean propor- tion of male to female births, during the whole period of the above ten years, was as 102.8 to 100 ; while in North Wales (where the average annual births are 12,873) it was as high as 106.2 to 100. Taking a still smaller district, viz., Rutlandshire (where the annual births average only 739), in 1864 the male births were as 114.6, and in 1862 as 97.0 to 100 ; but even in this small district the average of the 7,385 births 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 un- known causes ; thus Prof. Faye states that " in some dis- tricts of Norway there has been during a decennial period a steady deficiency of boys, while in others the opposite condition has existed." In France during forty-four years the male to the female births have been as 106.2 to 100; but during this period it has occurred five times in one de- partment, and six times in another, that the female births have exceeded the males. In Russia the average propor- tion is as high as 108.9 to 100.33 It is a singular fact that with Jews the proportion of male births is decidedly larger than with Christians ; thus in Prussia the proportion is as 113, in Breslau as 114, and in Livonia as 120 to 100; the Christian births in these countries being the same as usual, 32 ( Twenty-ninth Annual Report of the Registrar-General for I860.' In this report (p. xii) a special decennial table is given. 33 For Norway and Russia, see abstract of Prof. Faye's researches in British and Foreign Medico-Chirurg. Review,' April, 1867, pp. 343, 345, For France, the ( Annuaire pour l'An 18G7,' p. 213. 292 THE PRINCIPLES OF [Part II. for instance, in Livonia, as 104 to 100.34 It is a still more singular fact that in different nations, tinder different con- ditions and climates, in Naples, Prussia, Westphalia, France, and England, the excess of male over female births is less when they are illegitimate than when legiti- mate.36 In various parts of Europe, according to Prof. Fayc and other authors, " a still greater preponderance of males would be met with, if death struck both sexes in equal proportion in the womb and during birth. But the fact is that, for every 100 still-born females, we have in sev- eral countries from 134.6 to 144.9 still-born males." More- over during the first four or five years of life more male children die than females ; for example, in England, dur- ing the first year, 126 boys die for every 100 girls — a pro- portion Avhich in France is still more unfavorable." 36 As a consequence of this excess in the death-rate of male children, and of the exposure of men when adult to vari- ous dangers, and of their tendency to emigrate, the fe- males in all old-settled countries, where statistical records have been kept,37 are found to preponderate considerably over the males. 34 In regard to the Jews, see M. Thury, ' La Loi de Production des Sexes,' 1863, p. 25. 35 Babbage, 'Edinburgh Journal of Science,' 1829, vol. i. p. 88; also p. 90, on still-born children. On illegitimate children in England, see 'Report of Registrar-General for 1866,' p. xv. 36 'British and Foreign Medico-Chirurg. Review,' April, 1867, p. 343. Dr. Stark also remarks (' Tenth Annual Report of Births, Deaths, etc., in Scotland,' 1867, p. xxviii.) that "these examples may suffice to show that, at almost every stage of life, the males in Scotland have a greater liabil- ity to death and a higher death-rate than the females. The fact, how- ever, of this peculiarity being most strongly developed at that infantile period of life when the dress, food, and general treatment of both sexes are alike, seems to prove that the higher male death-rate is an impressed, natural, and constitutional peculiarity due to sex alone." With the savage Guaranys of Paraguay, according to the accurate 37 Chap. VIII.] SEXUAL SELECTION. 293 It has often been supposed that the relative ages of the parents determine the sex of the offspring ; and Prof. Leuckart 38 has advanced what he considers sufficient evi- dence, with respect to man and certain domesticated ani- mals, to show that this is one important 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 polyg- amy has been supposed to lead to the birth of a greater proportion of female infants ; but Dr. J. Campbell39 care- fully attended to this subject in the harems of Siam, and he concludes that the proportion of male to female births is the same as from monogamous unions. Hardly any animal has been rendered so highly polygamous as our English race-horses, and we shall immediately see that their male and female offspring "are almost exactly equal in number. Horses. — Mr. Tegetmeier has been so kind as to tabulate for me from the ' Racing Calendar ' the births of race-horses during a period of twenty-one years, viz., from 184G to 18G7; 18-19 being omitted, as no returns were that year published.. The total births have been 25,560,40 consisting of 12,763 males and 12,797 females, or in the proportion of 99.7 males to 100 females. As these num- Azara ('Voyages dans l'Amerique mend.,' torn. ii. 1809, pp. CO, 179), the women in proportion to the men are as 14 to 13. 38 Leuckart (in Wagner, ' Eandworterbuch der Phvs.' B. iv. 1853, s 771). 39 Anthropological Review, April, 1870, p. cviii. 40 During the last eleven years a record has been kept of the number of mares which have proved barren or prematurely slipped their foals ; «nnd it deserves notice, as showing how infertile these highly-nurtured and rather closely-interbred animals have become, that not far from one- third of the mares failed to produce living foals. Thus, during 1866, 809 male colts and 816 female colts were born, and 743 mares failed to pro. duce offspring. During 1867, 836 males and 902 females were born, and 794 mares failed. 294 THE PRINCIPLES OF [Part II. bers are tolerably large, and as they are drawn from all parts of England, during several years, we may witb much confidence conclude that with the domestic horse, or at least with the race- horse, the two sexes are produced in almost equal numbers. The fluctuations in the proportions during successive years are closely like those which occur with mankind, when a small and thinly- populated area is considered: thus in 1856 the male horses were as 107.1, and in 1867 as only 92.6 to 100 females. In the tabu- lated returns the proportions vary in cycles, for the males ex- ceeded the females during six successive years ; and the females exceeded the males during two periods each of four years : this, however, may be accidental ; at least I can detect nothing of the kind with man in the decennial table in the Eegistrar's Eeport 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 me 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, the births of a large number of greyhounds, throughout England, have been sent to the 'Field' newspaper; and I am again in- debted to Mr. Tegetmeier for carefully tabulating the results. The recorded births have been 6,878, consisting of 3,605 males and 3,273 females, that is, in the proportion of 110.1 males to 100 females. The greatest fluctuations occurred in 1864, when the proportion was as 95.3 males, and in 1867, as 116.3 males to 100 females. The above average proportion of 110.1 to 100 is prob- ably nearly correct in the case of the greyhound, but whether it would hold with other domesticated breeds is in some degree doubtful. Mr. Cupples has inquired 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 disap- pointment producing a stronger impression on the mind. Slieep. — The sexes of sheep are not ascertained by agricultur- ists until several months after birth, at the period when the males are castrated ; so that the following returns do not give the pro- portions at birth. Moreover, I find that several great breeders in Scotland, who annually raise some thousand sheep, are firmly Chap. VIIL] SEXUAL SELECTION. 295 convinced that a larger proportion of males than of females die during the first one or two years ; therefore the proportion of males would be somewhat greater at birth than at the age of cas- tration. This is a remarkable coincidence with what occurs, as we have seen, with mankind, and both cases probably depend on some common cause. I have received returns from four gentle- men in England who have bred lowland sheep, chiefly Leicesters, during the last ten or sixteen years ; they amount altogether to 8,905 births, consisting of 4,407 males and 4,558 females; that is, in the proportion of 96.7 males to 100 females. "With respect to Cheviot and black-faced sheep bred in Scotland, I have received returns from six breeders, two of them on a large scale, chiefly for the years 1867-1869, but some of the returns extending back to 1862. The total number recorded amounts to 50,685, consist- ing of 25,071 males and 25,614 females, or in the proportion of 97.9 males to 100 females. If we take the English and Scotch returns together, the total number amounts to 59,650, consisting of 29,478 males and 30,172 females, or as 97.7 to 100. So that with sheep at the age of castration the females are certainly in excess of the males; but whether this would hold good at birth is doubtful, owing to the greater liability in the males to early death.41 Of Cattle I have received returns from nine gentlemen of 982 births, too few to be trusted ; these consisted of 477 bull-calves and 505 cow-calves ; i. e., in the proportion of 94.4 males to 100 females. The Rev. "W. D. Fox informs me that in 1867 out of 34 calves born on a farm in Derbyshire only one was a bull. Mr. Harrison "Weir writes to me that he has inquired from several breeders of Pigs, and most of them estimate the male to the fe- male births as about 7 to 6. This same gentleman has bred Bad- bits for many years, and has noticed that a far greater number of bucks are produced than does. 41 I am much indebted to Mr. Cupples for having procured for me the above returns from. Scotland, as well as some of the following returns on cattle. Mr. R. Elliot, of Laighwood, first called my attention to the premature deaths of the males — a statement subsequently confirmed by Mr. Aitchison and others. To this latter gentleman, and to Mr. Payau, I owe my thanks for the larger returns on sheep. 296 THE PRINCIPLES OF [Part II. Of mammalia in a state of nature I have been able to learn very little. In regard to the common rat, I have received con- flicting statements. Mr. K. Elliot, of Laighwood, informs me that a rat-catcher assured him that he had always found the males in great excess, even with the young in the nest. In consequence of this, Mr. Elliot himself subsequently examined some hundred old ones, and found the statement true. Mr. F. Buckland has bred a large number of white rats, and he also believes that the males greatly exceed the females. In regard to Moles, it is said that "the males are much more numerous than the females; "4a and as the catching of these animals is a special occupation, the statement may perhaps be trusted. Sir A. Smith, in describing an antelope of South Africa 43 (Koous ellipsiprymnus), remarks, that in the herds of this and other species, the males are few in number compared with the females', the natives believe that they are born in this proportion ; others believe that the younger males are expelled from the herds, and Sir A. Smith says, that though he has himself never seen herds consisting of young males alone, others affirm that this does occur. It appears probable that the young males, when expelled from the herd, would be likely to fall a prey to the many beasts of prey of the country. BIRDS. With respect to the Fowl, I have received only one account, namely, that out of 1,001 chickens of a highly-bred stock of Co- chins, reared during eight years by Mr. Stretch, 487 proved males and 514 females: i. e., as 94.7 to 100. In regard to domestic pig- eons there is good evidence that the males are produced in excess, or that their lives are longer; for these birds invariably pair, and single males, as Mr. Tegetmeier informs me, can alway be pur- chased cheaper than females. Usually the two birds reared from the two eggs laid in the same nest consist of a male and female; but Mr. Harrison Weir, who has been so large a breeder, says that he has often bred two cocks from the same nest, and seldom two hens; moreover, the hen is generally the weaker of the two, and more liable to perish. 42 Bell, 'History of British Quadrupeds,' p. 100. 43 'Illustrations of the Zoology of South Africa,' 1849, pi. 29. Chap. VIII.] SEXUAL SELECTION. 297 With respect to birds in a state of nature, Mr. Gould and others 44 are convinced that the males are generally the more numerous; and as the young males of many species resemble the females, the latter would naturally appear to be the most numer- ous. Large numbers of pheasants are reared by Mr. Baker, of Leadenhall, from eggs laid by wild birds, and he informs Mr. Jen- ner Weir that four or five males to one female are generally pro- duced. An experienced observer remarks 45 that in Scandinavia the broods of the capercailzie and black-cock contain more males than females ; and that with the Dal-ripa (a kind of ptarmigan) more males than females attend the le7cs or places of courtship ; but this latter circumstance is accounted for by some observers by a greater number of hen-birds being killed by vermin. From various facts given by White of Selbourne,46 it seems clear that the males of the partridge must be in considerable excess in the south of England ; and I have been assured that this is the case in Scot- land. Mr. Weir, on inquiring from the dealers who receive at certain seasons large numbers of ruffs (Machetes pugnax), was told that the males are much the most numerous. This same natural- ist lias also inquired for me from the bird-catchers, who annually catch an astonishing number of various small species alive for the London market, and he was unhesitatingly answered by an old and trustworthy man, that with the chaffinch the males are in large excess; he thought as high as 2 males tol female, or at least as high as 5 to 3.4T The males of the blackbird, he likewise maintained, were by far the most numerous, whether caught by traps or by netting at night. These statements may apparently be trusted, because the same man said that the sexes are about equal with the lark, the twite (Linaria montana), and goldfinch. 44 Brehm (' Illust. Thierleben,' B. iv. s. 990) comes to the same con- clusion. 45 On the authority of L. Lloyd, 'Game Birds of Sweden,' 18G7, pp. 12, 132. 46 ' Nat. Hist, of Selbourne,' letter xxix. edit, of 1825, vol. i. p. 139. 47 Mr. Jenner Weir received similar information, on making inquiries during the following year. To show the number of chaffinches caught, 1 may mention that in 1869 there was a match between two experts; and one man caught in a day 62, and another 40, male chaffinches. The greatest number ever caught by one man in a single day was 70. 298 THE PRINCIPLES OF [Part II. On the other hand, he is certain that with the common linnet, the females preponderate greatly, but unequally during different years; during some years he has found the females to the males as four to one. It should, however, be borne in mind, that the chief sea- son for catching birds does not begin till September, so that with some species partial migrations may have begun, and the flocks at this period often consist of hens alone. Mr. Salvin paid par- ticular attention to the sexes of the humming-birds in Central America, and he is convinced that with most of the species the males are in excess ; thus, one year he procured 204 specimens belonging to ten species, and these consisted of 166 males and of 38 females. "With two other species the females were in excess : but the proportions apparently vary either during different sea- sons or in different localities; for on one occasion the males of Campylopterus hemileucurus were to the females as five to two, and on another occasion 48 in exactly the reversed ratio. As bear- ing on this latter point, I may add that Mr. Powys found in Corfu and Epirus the sexes of the chaffinch keeping apart, and " the fe- males by far the most numerous ; " while in Palestine Mr. Tris- tram found " the male flocks appearing greatly to exceed the fe- male in number." 49 So again with the Quiscalus major, Mr. G. Taylor 50 says that in Florida there were " very few females in proportion to the males," while in Honduras the proportion was the other way, the species there having the character of a po- lygamist. FISH. With fish the proportional numbers of the sexes can be ascer- tained only by catching them in the adult or nearly adult state ; and there are many difficulties in arriving at any just conclusion.61 Infertile females might readily be mistaken for males, as Dr. Gun- ther has remarked to me in regard to trout. With some species 48 ' Ibis,' vol. ii. p. 260, as quoted in Gould's ' TrochilidaV 1861, p. 52. For the foregoing proportions, 1 am indebted to Mr. Salvin for a table of his results. 49 'Ibis,' 1860, p. 137; and 1867, p. S69 50 'Ibis,' 1862, p. 137. 51 Leuckart quotes Bloch (Wagner, 'Handworterbuch der Phys.' B. ir. 1853, s. 775), that with fish there are twice as many males as females. Chap. VIII.] SEXUAL SELECTION. 299 the males are believed to die soon after fertilizing the ova. With 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. Carbonnier,52 who has especially attended to the natural history of the pike {Esox lucius) 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 Stormontfield experiments, says that in 18C5, out of 70 salmon first landed for the purpose of obtaining the ova, upward of GO were males. In 1867 he again " calls attention to the vast dispro- portion of the males to the females. "We had at the outset at least ten males to one female." Afterward sufficient females for obtaining ova were procured. He adds, "From the great propor- tion of the males, they are constantly fighting and tearing each other on the spawning-beds." 53 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. Buckland remarks in regard to trout, that "it is a curious fact that the males preponderate very largely in number over the fe- males. It 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. I cannot quite account for this ; either the males are more numerous than the females, or the latter seek safety by concealment rather than flight." He then adds that, by carefully searching the banks, sufficient females for obtaining ova can be found.54 Mr. II. Lee informs me that out of 212 trout, taken for this purpose in Lord Portsmouth's park, 150 were males and 62 females. With the Cyprinida) the males likewise seem to be in excess ; but several members of this family, viz., the carp, tench, bream, 52 Quoted in the 'Farmer,' March 18, 1869, p. 369. 58 ' The Stormontfield Piscicultural Experiments,' 1SGG, p. 23. The 'Field' newspaper, June 29, 1867. " 'Land and Water,' 1868, p. 41. 300 THE PRINCIPLES OF [Part II. and minnow, appear regularly to follow the practice, rare in the animal kingdom, of polyandry; for the female while spawning is always attended by two males, one on each side, and in the caso 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 spawn- ing-beds the males are ten times as numerous as the females; when a female comes among the males, "she is immediately pressed closely by a male on each side ; and when they have been in that situation for a time, are superseded by other two males." 65 INSECTS. In this class, the Lepidoptera alone afford the means of judg- ing of the proportional numbers of the sexes ; for they have been collected with special care by many good observers, and have been largely bred from the egg or caterpillar state. I had hoped that some breeders of silk-moths might have kept an exact record, but after writing to France and Italy, and consulting various treatises, I cannot find that this has ever been done. The gen- eral opinion appears to be that the sexes are nearly equal, but in Italy, as I hear from Prof. Oanestrini, 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 Ailantus silk-moth {Bombyx cynthia), the males greatly preponderate in the first, while 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 preponder- ance of the males.66 Thus Mr. Bates,67 in speaking of the species, 65 Yarrell, 'Hist. British Fishes,' vol. i. 1836, p. 307 ; on the Cyprinm tarpio, p. 331 ; on the Tinea vulgaris, p. 331 ; on the Abramis brama, p. 336. See, for the minnow (Lcuciscus phoxinus), 'Loudon's Mag. of Nat. Hist.' vol. v. 1832, p. 682. 56 Leuckart quotes Meinecke (Wagner, ' Handworterbuch der Phys.' B. iv. 1853, s. 1*15) that with Butterflies the males are three or foui times as numerous as the females. 57 « The Naturalist on the Amazons,' vol. ii. 1863, pp. 228, 347. Chap. VIII.] SEXUAL SELECTION. 301 no less 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, esti- mates in the genus Papilio the males to the females as four to one ; and Mr. Walsh, who informed me of this statement, says that with P. turnus this is certainly the case. In South Africa, Mr. E. Trimen found the males in excess in nineteen 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 spe- cies, in which the males are numerous in certain localities, he collected during seven years only five females. In the island of Bourbon, M. Maillard states that the males of one species of Papilio 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 60 states that the females of Ornithoptera crcesus, in the Malay archipelago, are more common and more easily caught than the males ; but this is a rare butter- fly. I may here add, that in Hyperythra, a genus of moths, Guen6e 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 ; but this fact was attributed by various observers to the more retiring habits of the females, and to the males emerging earlier from the cocoon. This latter circumstance is well known to occur with most Lepidoptera, as well as with other insects. So that, as M. Personnat remarks, the males of the domesticated Bomhyx yama-mai are lost at the beginning of the season, and 58 Four of these cases are given by Mr. Trimen in his c Rhopalocera Africfe Australis.' 63 Quoted by Trimen, ' Transact. Ent. Soc.' vol. v. part iv. 18G6, p. 830. 60 • Transact. Linn. Soc.' vol. xxv. p. 37. e"Proc. Entomolog. Soc.' Feb. 17, 1868. J02 THE PRINCIPLES OF [Part II. the females at the end, from the want of mates.62 I cannot, how- ever, persuade myself that these causes suffice to explain the great excess of males in the cases, 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 smaller moths, informs me that when he collected them in the imago state, he thought that the males were ten times as numerous as the females, but that, since he has reared them on a large scale from the caterpillar state, he is convinced that the females are the most numerous. Several entomologists concur in this view. Mr. Doubleday, however, and some others, take an opposite view, and are convinced that they have reared from the egg and cater- pillar states a larger proportion of males than of females. Besides the more active habits of the males, their earlier emergence 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 of the sexes of Lepidoptera, 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 Prof. Canestrini, that the female cater- pillar of the silk-moth suffers more from the recent disease than the male ; and Dr. Staudinger informs me that in rearing Lepi- doptera more females die in the cocoon than males. With many species the female caterpillar is larger than the male, and a col- lector would naturally choose the finest specimens, and thus" un- intentionally collect a larger number of females. Three collect- ors have told me that this was their practice ; but Dr. "Wallace is sure that most collectors take all the specimens which they can find of the rarer kinds, which alone are worth the trouble of rearing. Birds, when surrounded by caterpillars, would prob- ably devour the largest ; and Prof. Canestrini informs me that in Italy some breeders believe, though on insufficient evidence, that in the first brood of the Ailantus 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, 62 Quoted by Dr. Wallace in 'Proc. Eat. Soc' 3d series, vol. v. 1867, p. 487. Chap. YIIL] SEXUAL SELECTION. 303 and consume more food and moisture ; and thus they would be exposed during a longer time to danger from ichneumons, birds, etc., 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 are ready to propagate their kind. The manner in which the males of certain moths congregate in extraordinary numbers round a single female, apparently indi- cates a great excess of males, though this fact may perhaps be 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 ElacMsta rufocinerea. It is well known that if a virgin Lasiocampa quercus or Saturnia carpini be exposed in a cage, vast numbers of males collect round her, and if confined in a room will even come down the chimney to her. 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 endeavored to gain admittance. M. Verreaux, in Australia, having placed the female of a small Bombyx in a box in his pocket, was followed by a crowd of males, so that about two hundred entered the house with him.68 Mr. Doubleday has called my attention to Dr. Staudinger's64 list of Lepidoptera, which gives the prices of the* males and females of 300 species or well-marked varieties of (Rhopalocera) butterflies. The prices for both sexes of the very common species are of course the same; but with 114 of 'the rarer species they diner ; the males being in all cases, excepting one, the cheapest. On an average of the prices of the 113 species, the price of the male to that of the female is as 100 to 149 ; and this apparently indicates that inversely the males exceed the females in number in the same proportion. About 2,000 species or varieties of moths (Ileterocera) are catalogued, those with wingless females 63 Blanchard, 'Metamorphoses, Moeurs des Insectes,' 1868, pp. 225, 226, 64 ' Lepidopteren-Doubblettren Liste,' Berlin, No. x. 1866. 304 THE PRINCIPLES OF [Part II. being here excluded on account of the difference in habits of the two sexes : of these 2,000 species, 141 differ in price according to sex, the males of 130 being cheaper, and the males of only 11 being dearer than the females. The average price of 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 ac- counted for only by an excess in the numbers of the males. But I am bound to add that Dr. Staudinger himself, as he informs me, is of a different opinion. He thinks that the less active habits of the females and the earlier emergence of the males will account for his collectors securing a larger number of males than of females, and consequently for the lower prices of the former. "With respect to specimens reared from the caterpillar-state, Dr. Staudinger 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. Of direct observations on the sexes of Lepidoptera, reared either from eggs or caterpillars, I have received only the few fol- lowing cases : Males. Females. The Rev. J. Hellins,05 of Exeter, reared, during 18G8, imagos of 73 species, which consisted of 153 137 Mr. Albert Jones, of Eltham, reared, during 1868, imagos of 9 species, which consisted of 159 120 During 1869 he reared imagos from 4 species, consisting of 114 112 Mr. Buckler, of EmsworuY, Hants, during 1869, reared imagos from 74 species, consisting of 180 169 Dr. "Wallace, of Colchester, reared from one brood of Bombyx cynthia 52 48 Dr. Wallace raised, from cocoons of Bombyx Pernyi sent from China, during 1869 224 123 Dr. Wallace raised, during 1868 and 1869, from two lots of cocoons of Bombyx yama-mai 52 46 Total 934 761 So that in these eight lots of cocoons and eggs, males were produced in excess. Taken together, the proportion of males is 65 This naturalist has been so kind as to send me some results from former years, in which the females seemed to preponderate ; but so many of the figures were estimates, that I found it impossible to tabulate them Chip. VIII.] SEXUAL SELECTION. 305 as 122.7 to 100 females. But the numbers are hardly largo enough to be trustworthy. On the whole, from the above various sources of evidence, all pointing to the same direction, I infer that, with most species of Lepidoptera, the males in the imago state generally exceed the females in number, whatever the proportions may be at their first emergence from the egg. With reference to the other Orders of insects, I have been able to collect very little reliable information. With the stag- beetle (Lucamis cervus) " the males appear to be much more numerous than the females ; " but when, as Cornelius remarked during 1867, an unusual number of these beetles appeared in one part of Germany, the females appeared to exceed the males as six to one. With one of the Elaterida?, the males are said to be much more numerous than the females, and " two or three are often found united with one female ; " 66 so that here polyandry seems to prevail. With Siagonium (Staphylinidse), 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 bark-feeding Tomicus villosus are so common as to be a plague, while the males are so rare as to be hardly known. In other Orders, from unknown causes, but apparently in some instances owing to parthenogenesis, the males of certain species have never been discovered, or are excessively rare, as with several of the Cvni- 7 «/ 7 v pida?.67 In all the gall-making Cynipidae known to Mr. Walsh, the females are four or five times as numerous as the males ; and so it is, as he informs me, with the gall-making Cecidomyiiaa (Diptera). With some common species of Saw-flies (Tenthre- dince) Mr. F. Smith has reared hundreds of specimens from larvae of all sizes, but has never reared a single male : on the other hand, Curtis says,68 that with certain species (Athalia), bred by 06 GUnther's « Record of Zoological Literature,' 1867, p. 260. On tlio excess of female Lucamis, ibid. p. 250. On the males of Lucanus in Eng- land, Westwood, ' Modern Class, of Insects,' vol. i. p. 187. On the Sia- gonium, ibid, p 172. 67 Walsh, in 'The American Entomologist,' vol. i. 1869, p. 103. Y Smith, 'Record of Zoological Literature,' 1867, p. 328. 68 'Farm Insects,' pp. 45, 46. 14 306 THE PRINCIPLES OF [Part II. him, the males to the females were as six to one ; "while exactly the reverse occurred with the mature insects of the same species caught in the fields. With the Neuroptera, Mr. Walsh states that in many, but by no means in all, the species of the Odonatous groups (Ephemerina), there is a great overplus of males ; in the genus Hetserina, also, the males are generally at least four times as numerous as the females. In certain species in the genus Gomphus the males are equally numerous, while in two other species the females are twice or thrice as numerous as the males. In some European species of Psocus thousands of females may be collected without a single male, while with other species of the same genus both sexes are common.69 In England, MK Mac- Lachlan has captured hundreds of the female Apatania muliebris, but has never seen the male ; and of Boreus hyemalis only four or five males have been here seen.70 With most of these species (excepting, as I have heard, with the Tenthredinse), there is no reason to suppose that the females are subject to parthenogene- sis ; and thus we see how ignorant we are on the causes of the apparent discrepancy in the proportional numbers of the two sexes. In the other Classes of the Articulata I have been able to col- lect still less information. With Spiders, Mr. Blackwall, who has carefully attended to this class during many years, writes to me that the males, from their more erratic habits, are more com- monly seen, and therefore appear to be the more numerous. This is actually the case with a few species ; but he mentions several species in six genera, in which the females appear to be much more numerous than the males.71 The small size of the males in comparison with the females, which is sometimes car- ried to an extreme degree, and their widely-different appearance, may account in some instances for their rarity in collections.73 66 ' Observations on N. American Neuroptera,' by H. Hagan and B. D. Walsh, 'Proc. Ent. Soc. Philadelphia,' Oct. 1863, pp. 168, 223, 239. 70 Proc. Ent, Soc. London,' Feb. 17, 1868. 71 Another great authority in this class, Prof. Thorell of Upsala (' On European Spiders,' 1869-"70, part i. p. 205) speaks as if female spiders were generally commoner than the males. 72 See, on this subject Mr. Pickard-Cambridge, as quoted in ' Quar. terly Journal of Science,' 1868, p. 429. Chap. VIII.] SEXUAL SELECTION. 30 7 Some of the lower Crustaceans are able to propagate their kind asexually, and this will account for the extreme rarity of the males. With some other forms (as with Tanis and Cypris) there is reason to believe, as Fritz Miiller informs me, that the male is much shorter-lived 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, on the shores of Brazil, far more males than females of the Diastylida) and of Cypridina ; thus, with a species in the latter genus, sixty-three specimens caught the same day, included fifty-seven males ; but he suggests that this preponderance may be due to some unknown ditference in the habits of the two sexes. With one of the higher Brazilian crabs, namely, a Gelasimus, Fritz Miiller found the males to be more numerous than the females. The reverse seems to be the case, according to the large experience of Mr. 0. Spence Bate, with six common British crabs, the names of which he has given me. On the Power of Natural Selection to regulate the pro- portional Numbers of the Sexes, and General Fertility. — In 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 with those animals in which more than one male is requisite to ferti- lize the female, as with certain cirripedes and perhaps certain fishes. An inequality between the sexes in these cases might have been acquired through natural selection, but from their rarity they need not here be further con-, sidered. In all ordinary cases an inequality would be no advantage or disadvantage to certain individuals more than to others; and therefore it could hardly have re- sulted from natural selection. "VVe must attribute the inequality to the direct action of those unknown condi- tions, which with mankind lead to the males being born in a somewhat larger excess in certain countries than in others, or which cause the proportion between the sexes to differ slightly in legitimate and illegitimate births. 308 THE PRINCIPLES OF [Part II. Let us now take the case of a species producing, from the unknown causes iust alluded to, an excess of one sex — we will say of males — these being superfluous and use- less, or nearly useless. Could the sexes be equalized * through natural selection ? We may feel sure, from all characters being variable, that certain pairs would pro- duce a somewhat less excess of males over females than other pairs. The former, supposing the actual number of the offspring to remain constant, would necessarily pro- duce more females, and would therefore be more pro- ductive. On the doctrine of chances a greater number of the offspring of the more productive pairs would survive; and these would inherit a tendency to procreate fewer males and more females. Thus a tendency toward equali- zation of the sexes wrould be brought about. But our supposed species would by this process be rendered, as just remarked, more productive ; and this would in many cases be far from an advantage ; for, whenever the limit to the numbers which exist depends, not on destruction by enemies, but on the amount of food, increased fertility will lead to severer competition and to most of the sur- vivors being badly fed. In this case, if the sexes were equalized by an increase in the number of the females, a simultaneous decrease in the total number of the offspring wrould be beneficial, or even necessary, for the existence .of the species ; and this, I believe, could be effected through natural selection in the manner hereafter to be described. The same 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 such females from not uniting with males would be sivperfluous and useless. So it would be with polygamous species, if we assume the excess of females to be inordinately great. An excess of either sex, we will again say of the males,, could, however, apparently be eliminated through natural Chap. VIIL] SEXUAL SELECTION. 309 selection in another and indirect manner, namely, by an actual diminution of the males, without any increase of the females, and consequently without any increase in the productiveness of the species. From the variability of all characters, we may feel assured that some pairs, inhabit- ing any locality, would produce a rather smaller excess of superfluous males, but an equal number of productive females. When the offspring from the more and the less male-productive parents were all mingled together, none would have any direct advantage over the others ; but those that produced few superfluous males would have one great indirect advantage, namely, that their ova or embryos would probably be larger and finer, or their young better nurtured in the womb and afterward. We see this principle illustrated with plants ; as those whicli bear a vast number of seed produce small ones ; while those which bear comparatively few seeds, often produce large ones well-stocked with nutriment for the use of the seedlings.73 Hence the offspring of the parents which had wasted least force in producing superfluous males would be the most likely to survive, and would inherit the same tendency not to produce superfluous males, while retain- ing their full fortility in the production of females. So it would be with the converse case of the female sex. Any slight excess, however, of either sex could hardly be checked in so indirect a manner. Nor indeed has a con- siderable inequality between the sexes been always pre- vented, as we have seen in some of the cases given in the previous discussion. In these cases the unknown causes which determine the sex of the .embryo, and which under certain conditions lead to the production of one sex in 73 I have often been struck with the fact that, in several species of Primula, the seeds in the capsules which contained only a few were very much larger than the numerous seeda in the more productive cap- sules. 310 THE PRINCIPLES OF [Part II. excess over the other, have not been mastered by the sur- vival of those varieties which were subjected to the least waste of organized matter and force by the production of superfluous individuals of either sex. Nevertheless we may conclude that natural selection will always tend, though sometimes inefficiently, to equalize the relative numbers of the two sexes. Having said this much on the equalization of the sexes, it may be well to add a few remarks on the regula- tion through natural selection of the ordinary fertility of species. Mr. Herbert Spencer has shown in an able dis- cussion 74 that with all organisms a ratio exists between what he calls individuation and genesis ; whence it follows that beings which consume much matter or force in their growth, complicated structure, or activity, or which pro- duce ova and embryos of large size, or which expend much energy in nurturing their young, cannot be so pro- ductive as beings of an opposite nature. Mr. Spencer further shows that minor differences in fertility will be regulated through natural selection. Thus the fertility of each species will tend to increase, from the more fertile pairs producing a larger number of offspring, and these from their mere number will have the best chance of sur- viving, and will transmit their tendency to greater fer- tility. The only check to a continued augmentation of fertility in each organism seems to be either the expendi- ture of more power and the greater risks run by the parents that produce a more numerous progeny, or the contingency of very numerous eggs and young being pro- duced of smaller size, or less vigorous, or subsequently not so well nurtured. To strike a balance in any case be- tween the disadvantages which follow from the production of a numerous progeny, and the advantages (such as the 14 'Principles of Biology,' vol. ii. 1867, chaps. ii.-xL Chap. VIII. J SEXTTAL SELECTION. 311 escape of at least some individuals from various dangers) is quite beyond our power of judgment. When an organism has once been rendered extremely fertile, how its fertility can be reduced through natural selection is not so clear as how this capacity was first ac- quired. Yet it is obvious that if individuals -of a species, t'rom a decrease of their natural enemies, were habitually reared in larger numbers than could be supported, all the members would suffer. Nevertheless the offspring from the less fertile parents would have no direct advantage over the offspring from the more fertile parents, when all were mingled together in the same district. All the in- dividuals would mutually tend to starve each other. The offspring indeed of the less fertile parents would lie under one great disadvantage, for, from the simple fact of being produced in smaller numbers, they would be the most lia- ble to extermination. Indirectly, however, they would partake of one great advantage ; for, under the supposed condition of severe competition, when all were pressed for food, it is extremely probable that those individuals which from some variation in their constitution produced fewer eggs or young, would produce them of greater size or vigor; and the adults reared from such eggs or young would manifestly have the best chance of surviving, and would inherit a tendency toward lessened fertility. The parents, moreover, which had to nourish or provide for fewer offspring would themselves be exposed to a less se- vere strain in the struggle for existence, and would have a better chance of surviving. By these steps, and by no others as far as I can see, natural selection, under the above conditions of severe competition for food, would lead to the formation of a new race less fertile, but better adapted for survival, than the parent-race. 312 SEXUAL SELECTION [Tart II. CHAPTER IX. SECONDARY SEXUAL CHARACTERS IN THE LOWER CLASSES OF THE ANIMAL KINGDOM. These Characters absent in the Lowest Classes. — Brilliant Colors. — Mol- lusca. — Annelids.— Crustacea, Secondary Sexual Characters strongly developed; Dimorphism; Color; Characters not acquired before Maturity. — Spiders, Sexual Colors of; Stridulation by the Males.— Myriapoda. In the lowest classes the two sexes are not rarely united in the same individual, and therefore secondary sexual characters cannot be developed. In many cases in which the two sexes are separate, both are permanently attached to some support, and the one cannot search or struggle for the other. Moreover, it is almost certain that these animals have too imperfect senses and much too low mental powers to feel mutual rivalry, or to appreciate each other's beauty or other attractions. Hence in these classes, such as the Protozoa, Coelen- terata, 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 selection, which depends on the will, desires, and choice, of either sex. Nevertheless some few apparent exceptions occur; thus, as I hear from Dr. Baird, the males of certain Entozoa, or internal parasitic worms, diifer slightly in color from the females ; but we Chap. IX.] SEXUAL SELECTION. 313 have no reason to suppose that such differences have been augmented through sexual selection. 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 corals and sea-anem- ones (Actinia?), with some jelly-fish (Medusa?, Porpita, etc.), with some Planarise, Ascidians, numerous Star-fishes, Echini, etc. ; but we may conclude, from the reasons al- ready indicated, namely, the union of the two sexes in some of these animals, the permanently affixed condition of others,. and the low mental powers of all, that such col- ors do not serve as a sexual attraction, and have not been acquired through sexual selection. With the higher ani- mals the case is very different ; for with them when one sex is much more brilliantly or conspicuously colored 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 confirmed when the more ornament- ed individuals, which are almost always the males, dis- play their attractions before the other sex. We may also extend this conclusion to both sexes, when colored alike, if their colors are plainly analogous to those of one sex alone in certain other species of the same group. How, then, are we to account for the beautiful or even gorgeous colors of many animals in the lowest classes ? It appears very doubtful whether such colors usually serve as a protection ; but we are extremely liable to err in re- gard to characters of all kinds in relation to protection, as will be admitted by every one who has read Mr. Wal- lace's excellent essay on this subject. It would not, for instance, at first occur to any one that the perfect trans- parency of the Medusa?, or jelly-fishes, was of the highest service to them as a protection ; but when we are remind- 314 SEXUAL SELECTION. [Part IL ed by Hackel that not only the medusae but many float- ing mollusca, crustaceans, 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 ether enemies. Notwithstanding our ignorance how far color in many cases serves as a protection, the most probable view in re- gard to the splendid tints of many of the lowest animals seems to be that their colors are the direct result 'either of the chemical nature or the minute structure of their tissues, independently of any benefit thus derived. Hard- ly any color is finer than that of arterial blood ; but there is no reason to suppose that the color of the blood is in itself any advantage ; and though it adds to the beauty of the maiden's cheek, no one will pretend that it has been acquired for this purpose. So again with many animals, especially the lower ones, the bile is richly colored ; thus the extreme beauty of the Eolidse (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 thes.e animals. The tints of the decaying leaves in an American forest are described by every one as gorgeous ; yet no one supposes that these tints are of the least advantage to the trees. Bearing in mind how many substances closely analogous to natural organic compounds have been recently formed by chemists, and which exhibit the most splendid colors, it would have been a strange fact if substances similarly colored had not often originated, independently of any useful end being thus gained, in the complex laboratory of living organisms. The sub-kingdom of the Mollusca. — Throughout this great division (taken in its largest acceptation) of the animal kingdom, secondary sexual characters, such as we Chap. IX.] MOLLUSKS. 315 are here considering, never, as far as I can discover, occur. Nor could they be expected in the three lowest classes, namely, in the Ascidians, Polyzoa, and Brachiopods (con- stituting 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 Lamellibran- chiata, or bivalve shells, hermaphroditism is not rare. In the next higher class of the Gasteropoda, or marine uni- valve 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 flight- ing with other males. The sole external difference be- tween the sexes consists, as I am informed by Mr. Gwyn Jeffreys, in the shell sometimes differing a little in form; for instance, the shell of the male periwinkle (Littorina Uttorea) 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 repro- duction or with the development of the ova. The Gasteropoda, though capable of locomotion and furnished with imperfect eyes, do not appear to be en- dowed with sufficient mental powers for the members of the same sex to struggle together in rivalry, and thus to acquire secondary sexual characters. Nevertheless- with the pulmoniferous gasteropods, or land-snails, the pairing is preceded by courtship ; for these animals, though her- maphrodites, are compelled by their structure to pair to- gether. Agassiz remarks,1 " Quiconque a eu Poccasion d'observer les amours des limacons, ne saurait mettre en doute la seduction deployee dans les.mouvements et les allures qui preparent et accomplissent le double embrasse- ment de ces hermaphrodites." These animals appear also susceptible of some degree of permanent attachment: an accurate observer, Mr. Lonsdale, informs me that he placed 1 :De l'Espece et de la Class.' etc., 1869, p. 106. SI 6 SEXUAL SELECTION. [Part II. a pair of land-shells (Helix pomatia), one of which was weakly, into a small and ill-provided garden. After a short time the strong and healthy individual disappeared, and was traced by its track of slime over a wall into an adjoining well-stocked garden. Mr. Lonsdale concluded that it had deserted its sickly mate; but after an absence of twenty-four hours it returned, and apparently commu- nicated the result of its successful exploration, for both then started along the same track and disappeared over the wall. Even in the highest class of the Mollusca, namely, the Cephalopoda or cuttle-fishes, in which the sexes are sepa- rate, secondary sexual characters of the kind which we are here considering do not, as far as I can discover oc- cur. This is a surprising circumstance, as these animals possess highly-developed sense-organs and have consider- able mental powers, as will be admitted by every one who has watched their artful endeavors to escape from an enemy.2 Certain Cephalopoda, however, are characterized by one extraordinary sexual character, namely, that the male element collects within one of the arms or tentacles, which is then cast off, and, clinging by its sucking-disks to the female, lives for a time an independent life. So completely does the cast-off arm resemble a separate ani- mal, that it was described by Cuvier as a parasitic worm under the name of Hectocotyle. But this marvellous structure may be classed as a primary rather than as a secondary sexual character. Although with the Mollusca sexual selection does not seem to have come into play, yet many univalve and bivalve shells, such as volutes, cones, scallops, etc., are beautifully colored and shaped. The colors do not appear in most cases to be of any use as a protection ; they are 2 See, for instance, the account which I have given in my ' Journal of Researches,' 1845, p. 7. Ciiap. IX.J MOLLUSKS AND ANNELIDS. 31V probably the direct result, as in the lowest classes, of the nature of the tissues ; the patterns and the sculpture of the shell depending on its manner of growth. The amount of light seems to 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 colored, yet we generally see the lower sur- faces and the parts covered by the mantle less highly colored than the upper and exposed surfaces.3 In some cases, as with shells living among corals or brightly-tinted sea- weeds, the bright colors may serve *as a protection. But many of the nudibranch mollusca, or sea-slugs, are as beautifully colored as any shells, as may be seen in Messrs. Alder and Hancock's magnificent work ; and from information kindly given me by Mr. Hancock, it is ex- tremely doubtful whether these colors usually serve as a protection. With some species this may be the case, as with one which lives on the green leaves of algae, and is itself bright green. But many brightly-colored, white or otherwise conspicuous species, do not seek concealment ; while again some equally conspicuous species, as well as other dull-colored kinds, live under stones and in dark re- cesses. So that, with these nudibranch mollusks, color apparently does not stand in any close relation to the na- ture of the places which they inhabit. These naked sea-slugs are hermaphrodites, yet they pair together, as do land-snails, many of which have ex- tremely pretty shells. It is conceivable that two hermaph- rodites, attracted by each other's greater beauty, might unite and leave offspring which would inherit their par- ents' greater beauty. But with such lowly-organized 8 I have given (' Geolog. Observations on Volcanic Islands,1 1844, p. 63) a curious instance of the influence of light on the colors of a fron- descent incrustation, deposited by the surf on the coast-rocks of Ascen. sion, and formed by the solution of triturated sea-shells. 3 1 8 SEXUAL SELECTION. [Part II. creatures this is extremely improbable. Nor is it at all obvious how the offspring from the more beautiful pfiirs of hermaphrodites would have any advantage, so as to in- crease in numbers, over the offspring of the less beautiful, unless indeed vigor and beauty generally coincided. We have not here a number of males becoming mature before the females, and the more beautiful ones selected by the more vigorous females. If, indeed, brilliant colors were beneficial to an hermaphrodite animal in relation to its general habits of life, the more brightly-tinted individuals would succeed loest and would increase in number ; but this would be a case of natural and not of sexual selection. Sub-kingdom of the Vermes or Annulosa : Class, An- nelida (or Sea-worms). — In this class, although the sexes (when separate) sometimes differ from each other in char- acters of such importance that they have been placed un- der 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 preced- ing classes, apparently stand too low in the scale for the individuals of either sex to exert any choice in selecting a partner, or for the individuals of the same sex to strug- gle together in rivalry. Sub-kingdom of the Arthropoda : Class, Crustacea. — In this great class we first meet with undoubted second- ary sexual characters, often developed in a remarkable 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, and they alone are furnished with perfect swimming-legs, antennte and sense-organs ; the females being; destitute of these or- gans, with their bodies often consisting of a mere dis- Chap. IX.] CRUSTACEANS. 319 torted mass. But these extraordinary differences between the two sexes are no doubt related to their widely-differ- ent 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 numerous in the males than in the" females. As the males, without any unusual development of their olfactory organs, would almost certainly be able sooner or later to find the females, the increased number of the smelling - threads has probably been acquired through sexual selection, by the better provided males having been the most successful in finding partners and in leaving offspring. Fritz Miiller has described a re- markable dimorphic 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 chelae or pincers which serve to hold the female. Fritz Miiller sug- gests that these differences between the two male forms of the same species must have originated in certain indi- viduals having varied in the number of the smelling- threads, while other individuals varied in the shape and size of their chelae ; so that of the former, those which were best able to find the female, and of the latter, those which were best able to hold her when found, have left the greater number of progeny fo inherit their respective advantages.4 In some of the lower crustaceans, the right-hand an- terior antenna of the male differs greatly in structure 4 ' Facts and Arguments for Darwin,' English translat. 1869, p. 20. See the previous discussion on the olfactory threads. Sars has described a somewhat analogous case (as quoted in 'Nature,' 1870, p. 455) in a Norwegian crustacean, the Pontoporeia affinis. 320 SEXUAL SELECTION. [Part II. a from the left-hand one, the latter resembling in its sim- ple tapering joints the antennae of the female. In the male the modified antenna is either swollen in the middle or angu- larly bent, or converted (fig. 3) into an elegant, and sometimes wonderfully complex, prehensile organ.5 It serves, as I hear from Sir J. Lubbock, to hold the fe- male, and for this same purpose one of the two posterior legs (b) on the same side of the body is converted into a forceps. In an- other family the inferior or pos- terior antenna? are "curiously zig- zagged " in the males alone. In the higher crustaceans the anterior legs form a pair of chelae or pincers, and these are gener- ally larger in the male than in the female. In many species the Fig. 3.— Labirtocera Darwinii chelae On the Opposite sides of the (from Lubbock). l l . . a. Part of ns?ht-band anterior body are of unequal Size, the right- antenna of male, forming a l-i i • T ~~» :^-T^„*^^^ prehensile oro-an hand one being, as I am mlormea *' P£o?SerSfthethoraciC by Mr. D. Spence Bate, generally, c. Ditto of female. though not invariably, the largest. This inequality is often much greater in the male than in the female. The two chelae also often differ in structure (figs. 4, 5 and 6), the smaller one resembling those of the fe- male. What advantage is gained by their inequality in size 5 See Sir J. Lubbock in 'Annals, and Mag. of Nat. Hist.' vol. xi. 1853, pis. i. and x. ; and vol. xii. (1853) pi. vii. See also Lubbock in • Transact. Ent, Soc' vol. iv. new series, 1856-1858, p. 8. With respect to the zig- zagged antennae mentioned below, see Fritz Miiller, ' Facts and Argu- ments for Darwin,' 1869, p. 40, foot-note. Chap. IX.] CRUSTACEANS. 321 on the opposito sides of the body, and by the inequality be- ing much greater in the male than in the female ; and why, Fig. 4. — Anterior part of body of Callianassa (from Milne-Edwards), showing the unequal and differently-constructed right and left-liand chelae of the male. N. B.— The artist by mistake has reversed the drawing, and made the left- hand chela the largest. Fie:. 5. Fig. 6. pI6. 5.— Second lesj of male Orchestia Tucuratinga (from Fritz Miiller). Fig. 6.— Ditto of female. when they are of equal size, both are often much larger in the male than in the female, is not known. The chelae are sometimes of such length and size that they cannot possibly be used, as I hear from Mr. Spence Bate, for car- rying food to the mouth. In the males of certain fresh- water prawns (Pala3mon) the right leg is actually longer 822 SEXUAL SELECTION. [Part II. than the whole body.6 It is probable that the great size of one leg with its chelae may aid the male in fighting with his rivals ; but this use will not account for their in- equality 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 showing that they pair, and the male closes the mouth of the burrow with one of its chela?, 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 case. The sexes, however, of the common shore-crab ( Carcinus mcenas), 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 moult- ing, she could then be seized with impunity. Fritz Miiller states that certain species of Melita are distinguished from all other amphipods by the females having " the coxal lamellae of the penultimate pair of feet produced into hook-like processes, of which the males lay hold with the hands of the first pair." The development of these hook-like processes probably resulted from those females which were the most securely held during the act of reproduction having left the largest number of off- spring. Another Brazilian amphipod (Orchestia Dar~ winii, fig. 7) is described, by Fritz Miiller, as presenting a case of dimorphism, like that of Tanais ; for there are two 6 See a paper by Mr. C. Spence Bate, with figures, in ' Proc. Zoolog. Soc.' 1868, p. 363; and on the nomenclature of the genus, ibid. p. 585. I am greatly indebted to Mr. Spence Bate for nearly all the above state- ments with respect to the chelae of the higher crustaceans. ' 'Hist. Nat. des Crust.' torn. ii. 1837, p. 50. Chap. IX!] CRUSTACEANS. 323 male forms, which differ in the structure of their chelae.' As chelae of either shape would certainly have sufficed to hold the female, for both are now used for this purpose, the two male forms probably originated, by some having varied in one manner and some in another ; both forms having derived certain special but nearly equal 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 ; for with most animals when the male is larger than the female, he seems to have acquired his greater size by having con- quered 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, how- ever, in which the sexes follow different habits of life, and most of the Entomostraca must be excepted. The chelae of many crustaceans are weapons well adapted for fight- ing. Thus a Devil-crab (Portunus puber) was seen by a son of Mr. Bate fighting with a Carcinus mmias, and the latter was soon thrown on its back, and had every limb torn from its body. When several males of a Brazilian Gelasimus, a species furnished with immense pincers, were placed together by Fritz Muller in a glass vessel, they mutilated and killed each other. Mr. Bate put a large male Carcinus mcenas into a pan of water, inhabited by a female paired with a smaller male ; the latter was soon dispossessed, but, as Mr. Bate adds, " if they fought, the victory was a bloodless one, for I saw no wounds." This same naturalist separated a male sand-skipper (so common on our sea-shores), Gammarus marinus, from its female, both of which were imprisoned in the same vessel with many individuals of the same species. The female, being thus divorced, joined her comrades. After an interval the • Fritz Muller, ' Facts and Arguments for Darwin,' 1869, pp 25-28. 324 SEXUAL SELECTION. '[Part II. male was again put into the same vessel and he then, after swimming about for a time, dashed into the crowd, and without any. fighting at once took away his wife. This Fig. 7. — Orcbestia Darwinii (from Fritz Miiller), showing the differently-con' etructed chelse of the two male forms. fact shows that in the Amphipoda, an order low in the scale, the males and females recognize each other, and are mutually attached. Chap. IX.] CRUSTACEANS. 325 The mental powers of the Crustacea are probably higher than might have been expected. Any one who has tried to catch one of the shore-crabs, so numerous on many tropical coasts, will have perceived how wary and alert they are. There is a large crab (Birgus latro), found on coral islands, which makes at the bottom of a deep burrow a thick bed of the picked fibres of the cocoa-nut. It feeds on the fallen fruit of this tree by tearing off" the husk, fibre by fibre ; and it always begins at that end where the three eye-like depressions are situated. It then breaks through one of these eyes by hammering with its heavy front pincers, and, turning round, extracts the al- buminous core with its narrow posterior pincers. But these actions are probably instinctive, so that they would be performed as well by a young as by an old animal. The following case, however, can hardly be so considered : A trustworthy naturalist, Mr. Gardner,9 while watching a shore-crab (Gelasimus) making its burrow, threw some shells toward the hole. One rolled in, and three other shells remained within a few inches of the mouth. In about five minutes the crab brought out the shell which had fallen in, and carried it away to the distance of a foot ; it then saw the three other shells lying near, and evidently thinking that they might likewise roll in, carried them to the spot where it had laid the first. It would, I think, be d'fficujt to distinguish this act from one per- formed by man by the aid of reason. With respect to color which so often differs in the two sexes of animals belonging to the higher classes, Mr. Spence Bate does not know of any well-marked instances with our British crustaceans. In some cases, however, the male and female differ somewhat in tint, but Mr. Bate 9 'Travels in the Interior of Brazil,' 1846, p. 111. I have given, in my ' Journal of Researches,' p. 463, an account of the hahits of the Birgos. 326 SEXUAL SELECTION. [Paet II. thinks not more than may be accounted for by their dif- ferent habits of life, such as by the male wandering more about and being thus more exposed to the light. In a curious Bornean crab, which inhabits sponges, Mr. Bate could always distinguish the sexes by the male not having the epidermis so much rubbed off. Dr. Power tried to distinguish by color the sexes of the species which inhabit the Mauritius, but always failed, except with one species of Squilla, proably the JS. stylifera, the male of which is described as being " of a beautiful blu- ish-green," with some of the appendages cherry-red, while the female is clouded with brown and gray, " with the red about her much less vivid than in the male."18 In this case, we may suspect the agency of sexual selection. With Sapbirina (an oceanic genus of Entomostraca, and there- fore low in the scale) the males are furnished with minute shields or cell-like bodies, which exhibit beautiful chan- ging colors ; these being absent in the females, and in the case of one species in both sexes.11 It would, however, be extremely rash to conclude that these curious organs serve merely to attract the females. In the female of a Brazil- ian species of Gelasimus, the whole body, as I am informed by Fritz Mtiller, is of a nearly uniform grayish-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 colors are liable to change in the course of a few minutes — the white becoming dirty-gray or even black, the green " los- ing much of its brilliancy." The males apparently are much more numerous than the females. It deserves es- pecial notice that they do not acquire their bright colors until they become mature. They differ also from the fe- 10 Mr. Ch. Fraser, in 'Proc. Zoolog. Soc.' 1869, p. 3. I am indebted to Mr. Bate for the statement from Dr. Power. 11 Claus, 'Die freilebenden Copepoden,' 1863, s. 35. Chap. IX.] SPIDERS. 327 males in the larger size of their chelae. In some species of the genus, probably in all, the sexes pair and inhabit the same burrow. They are also, as we have seen, highly- intelliofent animals. From the various considerations it seems highly probable that the male in this species has be- come gayly ornamented in order to attract or excite the female. It has just been stated that the male Gelasimus does not acquire his conspicuous colors until mature and nearly ready to breed. This seems the general rule in the whole class with the many remarkable differences in structure between the two sexes. We shall hereafter find the same law prevailing throughout the great sub-kingdom of the Vertebrata, and in all cases it is eminently distinctive of characters which have been acquired through sexual se- lection. Fritz Muller 12 gives some striking instances of this law ; thus the male sand-hopper (Orchestia) does not acquire his large claspers, which are very differently con- structed from those of the female, until nearly full grown ; while young his claspers resemble those of the female. Thus, again, the male Brachyscelus possesses, like all other amphipods, a pair of posterior antennae ; the female, and this is a most extraordinary circumstance, is destitute of them, and so is the male as long as he remains immature. Class, Arachnida (Spiders). — The males are often darker, but sometimes lighter than the females, as may be seen in Mr. BlackwalFs magnificent work.13 In some spe- cies the sexes differ conspicuously from each other in col- or; thus the female of Sparassus smaragdulus is dullish green , while the adult male has the abdomen of a fine yellow, with three longitudinal stripes of rich red. In 12 ' Facts and Arguments,' etc., p. 79. :3 'A History of the Spiders of Great Britain,' 1861-18G4. For the following facts, see pp. 102, 77, 88. 328 SEXUAL SELECTION. [Part II. some species of Thomisus the two 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, while the front legs of the male are reddish-brown : in T. Jloricolens, the legs of the female are pale-green, those of the male being ringed in a conspicuous manner with vari- ous tints. Numerous analogous cases could be given in the genera Epeira, Nephila, Philodromus, Theridion, Liny- phia, etc. It is often difficult to say which of the two sexes departs most from the ordinary coloration of the genus to which the species belong; but Mr. Blackwall thinks that, as a general rule, it is the male. Both sexes while young, as I am informed by the same author, usu- ally resemble each other ; and both often undergo great changes in color during- their successive moults before ar- riving at maturity. In other cases the male alone appears to change color. Thus the male of the above-mentioned brightly-colored Sparassus at first resembles the female and acquires his peculiar tints only when nearly adult. Spiders are possessed of acute senses, and exhibit much intelligence. The females often show, as is well known, the strongest affection for their eggs, which they carry about enveloped in a silken web. On the whole, it ap- pears probable that well-marked differences in color be- tween the sexes have generally resulted from sexual se- lection, either on the male or . female side. But doubts may be entertained on this head from the extreme varia- bility in color of some species, for instance, of Theridion lineatum, the sexes of which differ when adult ; this great variability indicates that their colors have not been sub- jected to any form of selection. Mr. Blackwall does not remember to have seen the males of any species fighting together for the possession of the female. Nor, judging from analogy, is this proba- ble ; for the males are generally much smaller than the Chap. IX.] SPIDERS. 329 females, sometimes to an extraordinary degree.14 Had the males been in the habit of fighting together, they would, it is probable, have gradually acquired greater size and strength. Mr. Blackwall has sometimes seen two or more males on the same web with a single female ; but their courtship is too tedious and prolonged an affair to be easily observed. The male is extremely cautious in making his advances, as the female carries her coyness to a dangerous pitch. De Geer saw a male that " in the midst of his preparatory caresses was seized by the object of his attentions, enveloped by her in a web and then de- voured, 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 Theridion 16 have the power of making a stridulating sound (like that made by many beetles and other insects, but feebler), while 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 14 Aug. Vinson (' Araneides des lies de la Reunion,' pi. vi. figs. 1 and 2) gives a good instance of the small size of the male Epeira nigra. In this species, as I may add, the male is testaceous and the female black with legs banded with red. Other even more striking cases of inequality in size between the sexes have been recorded (' Quarterly Journal of Science,' 1868, July, p. 429); but I have not seen the original accounts. 15 Kirby and Spence, c Introduction to Entomology,' vol. i. 1818, p. 280. 16 Theridion (Asagena, 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, ' Ara- neae Svecicae,' p. 184. 15 830 SEXUAL SELECTION. [Part II. 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, can I find any well-marked instances of sexual differences such as more particularly concern us. In Glomeris limbata, however, and perhaps in some few other species, the males differ slightly in color from the females ; but this Glomeris is a highly-variable species. In the males of the Diplo- poda, the legs belonging 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 som*e 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 appendages at the extremity of the body for holding the male.17 17 Walckenaer et P. Gervais, ' Hist. Nat. des Insectes ; Apteres, torn. iv. ISil, pp. 17, 19, 68. Chap. X.1 INSECTS. 331 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 under- stood.— Difference in Size between the Sexes. — Thysanura. — Diptera. — Herniptera. — Homoptera, Musical Powers possessed by the Males alone. — Orthoptera, Musical Instruments of the Males, much diversi- fied in Structure ; Pugnacity ; Colors. — Neuroptera, Sexual Differences in Color. — Hymenoptera, Pugnacity and Colors. — Coleoptera, Colors ; furnished with Great Horns, apparently as an Ornament; Battles; Stridulating Organs generally common to Both Sexes. In the immense class of insects the sexes sometimes differ in their organs for locomotion, and often in their sense-organs, as in the pectinated and beautifully plumose antennae of the males of many species. In 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 Mutillidae, which are likewise destitute of wings. But we are chiefly concerned with structures by which one male is enabled to conquer another, either in battle or courtship, through his strength, pugnacity, ornaments, or music. The innumerable contrivances, therefore, by which the male is able to seize the female, may be briefly passed over. Besides the complex structures at the apex of the 1 Sir J. Lubbock, ■ Transact. Linnean Soc.' vol. xxv. 1866, p. 484. With respect to the Mutillidae see Westwood, ' Mod. Class, of Insects,' vol. ii. p. 213. ?32 SEXUAL SELECTION. [Part II. abdomen, which ought perhaps to be ranked as primary organs,2 " it is astonishing," as Mr. B. D. Walsh 3 has re- marked, "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 cornutus (a neuropterous insect in some degree allied to the Dragon-flies, etc.) has immense 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.4 One of the stag- beetles of North America {JLucanus 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 (Ammophila) the jaws in the two sexes are closely alike, but are used for widely-different pur- poses ; the males, as Prof. Westwood observes, " are ex- ceedingly ardent, seizing their partners round the neck with their sickle-shaped jaws ; " 6 while the females use 2 These organs in the male often differ in closely-allied species, and afford excellent specific characters. But their importance under a func- tional point of view, as Mr. R. MacLachlan has remarked to me, has probably been overrated. It has been suggested, that slight differences m these organs would suffice to prevent the intercrossing of well-marked varieties or incipient species, and would thus aid in their development. That this can hardly be the case, we may infer from the many recorded cases (see, for instance, Bronn, 'Geschichte der Natur,' B. ii. 1843, a. 164 ; and Westwood, 'Transact. Ent. Soc.' vol. iii. 1842, p. 195) of dis- tinct species having been observed in union. Mr. MacLachlan informs me (vide 'Stett. Ent. Zeitung,' 1867, s. 155) that when several species of Phryganidae, which present strongly-pronounced differences of this kind, were confined together by Br. Aug. Meyer, they coupled, and one pair produced fertile ova. 3 ' The Practical Entomologist,' Philadelphia, vol. ii. May, 1867, p. 88. 4 Mr. Walsh, ibid. p. 107. 5 ' Modern Classification of Insects,' vol. ii. 1840, pp. 206, 205. Mr. Walsh, who called my attention to this double use of the jaws, says that he has repeatedly observed this fact. Chap. X.] INSECTS. 333 these organs for burrowing in sand-banks and making their nests. The tarsi of the front-legs are dilated in many male beetles, or are furnished with broad cushions of hairs; and in many genera of water-beetles they are armed with a round flat sucker, so that the male may adhere to the slippery body of the female. It is a much more unusual cir- cumstance that the females of some water-beetles (Dytiscus) have their elytra deeply grooved, and in Acilius sul- catus thickly set with hairs, as an aid to the male. The females of some other water- beetles (Hydroporus) have their elytra punctured for the same object.6 In the male of Crabro cribrarius (fig. 8), it is the tibia which is dilated into a broad horny plate, with mi- nute membraneous dots, giv- ing to it a singular appearance like that of a riddle.7 In the male of Penthe (a genus of beetles) a few of the middle joints of the antennas are dilated and furnished on the inferior surface with cushions of hair, exactly like those on the tarsi of the Carabidae, ' 6 We have here a curious and inexplicable case of dimorphism, for some of the females of four European species of Dytiscus, and of certain species of Hydroporus, have their elytra smooth ; and no intermediate gradations between sulcated or punctured and quite smooth elytra have been observed. See Dr. n. Schaum, as quoted in the ' Zoologist,' vol. v.-vi. 1847-48, p. 1896. Also Kirby and Spence, 'Introduction to En- tomology,' vol. iii. 1826, p. 305. 7 Westwood, ' Modern Class.' vol. ii. p. 193. The following statement Fig. 8.— Crabro cribrarius. Upper figure, ma e ; lower figure, female. 334 SEXUAL SELECTION. [Part II. "and obviously for the same end." In male dragon-flies, " the appendages at the tip of the tail are modified in an almost infinite variety of curious patterns to enable them to embrace the neck of the female." Lastly, in the males of many in- sects, the legs are furnished with peculiar spines, knobs, or spurs ; or the whole leg is bowed or thickened, but this is by no means invariably a sexual character ; or one pair, or all three pairs are elongated, sometimes to an extravagant length.8 In all the orders, the sexes of many species present differences, of which the meaning is not understood. One curious case is that of a beetle (fig. 9), the male of which has the left mandible much enlarged ; so that the mouth is greatly distorted. In another Carabidous beetle, the Eurygna- thus,9 we have the unique case, as far as known to Mr. Wollaston, of the head of the female being much broader and larger, though in a variable degree, than that of the male. Any number of such cases could be given. They abound in the Lepidoptera : one of the most extraordinary is that cer- tain male butterflies have their fore-legs more or less atrophied, with the tibiae and deres distortus tarsi reduced to mere rudimentary knobs. (much enlarged). J Tipper figure, The winsrs, also, in the two sexes often differ male; lower fig- to ' ' ure, female. m neuration,10 and sometimes considerably about Penthe, and others in inverted commas, are taken from Mr. Walsh, 1 Practical Entomologist,' Philadelphia, vol. ii. p. 88. 8 Kirby and Spence, ' Introduct.' etc., vol. iii. pp. 332-336. 9 'Insecta Maderensia,' 1854, p. 20. 10 E. Doubleday, 'Annals and Mag. of Nat. Hist.' vol. i. 1848, p. 379. Fig. 9. — Taphro- Chap. X.] INSECTS. 335 in outline, as in the Arieoris epitus, which was shown to me in the British Museum by Mr. A. Butler. The males of certain South American butterflies have tufts of hair on the margins of the wings, and horny excrescences on the disks of the posterior pair.11 In several British butterflies, the males alone, as shown by Mr. Wonfor, are in parts clothed with peculiar scales. The purpose of the luminosity in the female glow- worm is likewise not understood ; for it is very doubtful whether the primary use of the light is to guide the male to the female. It is no serious objection to this latter be- lief that the males emit a feeble light ; for secondary sexu- al characters proper to one sex are often developed in a slight degree in the other sex. It is a more valid objection that the larvse shine, and in some species brilliantly : Fritz M tiller informs me that the most luminous insect which he ever beheld in Brazil was the larva of some beetle. Both sexes of certain luminous species of Elater emit light. Kirby and Spence suspect that the phosphorescence serves to frighten and drive away enemies. Difference in Size between the Sexes. — With insects of all kinds the males are commonly smaller than the fe- males ; 12 and this difference can often be detected even in the larval state. So considerable is the difference between the male and female cocoons of the silk-moth (Bombyx mori), that in France they are separated by a particular mode of weighing.13 In the lower classes of the animal I may add that the wings in certain Hyraenpptera (see Shuckard, ' Fosso- rial Hyraenop.' 1837, pp. 39-43) differ in neuration according to sex. 11 H. W. Bates, in 'Journal of Proc. Linn. Soc.' vol. vi. 1862, p. 74. Mr. Wonfor's observations are quoted in 'Popular Science Review,' 1868, p. 343. 18 Kirby and Spence, 'Introduction to Entomology,' vol. iii. p. 299. 13 Robinet, 'Vers a Soie,' 1848, p. 207. 336 SEXUAL SELECTION. [Part II. kingdom, the greater size of the females seems generally to depend on their developing an enormous number of ova ; and this may to a certain extent hold good with insects. But Dr. Wallace has suggested a much more probable ex- planation. He finds, after carefully attending to the de- velopment of the caterpillars of JBombyx cynthia and yama-mai, and especially of some dwarfed caterpillars reared from a second brood on unnatural food, "that in proportion as the individual moth is finer, so is the time required for its metamorphosis longer ; and for this reason the female, which is the larger and heavier insect, from having to carry her numerous eggs, will be preceded by the male, which is smaller and has less to mature." 14 Now, as most insects are short-lived, and as they are exposed to many dangers, it would manifestly be advantageous to the female to be impregnated as soon as possible. This end would be gained by the males being first matured in large numbers ready for the advent of the females; and this again would naturally follow, as Mr. A. R. Wallace has remarked,16 through natural selection ; for the smaller males would be first matured, and thus would procreate a large number of- offspring which would inherit the reduced size of their male parents, while the larger males from be- ing matured later would leave fewer offspring. There are, however, exceptions to the rule of male in- sects being smaller than the females ; and some of these exceptions are intelligible. Size and strength would be an advantage to the males, which fight for the 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 not known to fight together, of which the males exceed the females in size • and the meaning of this fact is not known ; but in some 14 ' Transact. Ent. Soc' 3d series, vol. v. p. 486. 15 'Journal of Proc. Ent. Soc.' Feb. 4, 1867, p. Ixxi. Ciiap. X.] INSECTS. 337 of these cases, as with the huge Dynastes and Megasoma, we can at least see that there would be no necessity for the males to be smaller than the females, in order to be matured before them, for these beetles are not short-lived, and there would be ample time for the pairing of the sexes. So, again, male dragon-flies (Libellulidse) are sometimes sensibly larger, and never smaller, than the females :16 and they do not, as Mr. MacLachlan believes, generally pair with the females, until a week or fortnight has elapsed, and until they have assumed their proper masculine colors. But the most curious case, showing on 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 the whole of this large group the males, in accordance' with the general rule, are smaller than the females and emerge about a week before them ; but among the Bees, the males of Apis mellifica, Anthi- dium manicatum and Anthophora acervomm, and among the Fossores, the males of the Methoca ichneumonides, are larger than the females. The explanation of this anomaly is that a marriage-flight is absolutely necessary with these species, and the males require great strength and size in order to carry the females through the air. In- creased size has here been acquired in opposition to the usual relation between size and the period of development, for the males, though larger, emerge before the smaller fe- males. 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. 16 For this and other statements on the size of the sexes, see Kirby and Spence, ibid. vol. iii. p. 300 ; on the duration of life in insects, see p. 344. 338 SEXUAL SELECTION. [Part h. Order, Thysanura. — The members of this Order are lowly organized for their class. They are wingless, dull- colored, minute insects, with ugly, almost misshapen heads and bodies. The sexes do not differ ; but they offer one interesting fact, by showing that the males pay sedulous court to their females even low down in the animal scale. Sir J. Lubbock,17 in describing the Smynthurus luteus, says : " It is very amusing to see these little creatures co- quetting together. The male, which is much smaller than the female, runs round her, and they butt one another, standing face 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 antenna) ; then for a bit they stand face to face, play with their an- tenna?, and seem to be all in all to one another." Order, Diptera (Flies). — The sexes differ little in color. The greatest difference, known to Mr. F. Walker, is in the genus Bibio, in which the males are blackish or quite black, and the females obscure brownish orange. The genus Elaphomyia, discovered by Mr. Wallace 18 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 spe- cies. They might be thought to serve for fighting, but, as in one species they are of a beautiful pink-color, edged with black, with a pale central stripe, and as these insects have altogether a very elegant appearance, it is perhaps 17 ' Transact. Linnean Soc' vol. xxvi. 1868, p. 296. ' The Malay Archipelago,' vol. ii. 1869, p. 313. Chap. X.] DirTERA AND HEMIPTERA. 339 more probable that the horns serve as ornaments. That the males 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 (Culicidse) dance in the air in a body, alternately rising and falling, the males are courting the females. The mental faculties of the Diptera are probably fairly well developed, for their nervous system is more highly developed than in most other Orders of in- sects.20 Order, Uemiptera (Field-Bugs). — Mr. J. W. Douglas, who has particularly attended to the British species, has kindly given me an account of their sexual differences. The males of some species are furnished with wings, while the females are wingless ; the sexes differ in the form of the body and elytra ; in the second joints of their antennae and in their tarsi ; but, as the signification of these differences is quite unknown, they may be here passed over. The females are generally larger and more robust than the males. With British, and, as far as Mr. Douglas knows, with exotic species, the sexes do not com- monly differ much in color ; but in about six British spe- cies 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 colors serve as a protection.. If in any species the males had differed from the females in an analogous manner, we might have been justified in attributing such conspicuous colors to sexual selection with transference to both sexes. Some species of lteduvidoe make a stridulating noise ; 19 'Modern Classification of Insects,' vol. ii. 1840, p. 526. 80 See Mr. 13. T. Lowne's very interesting work, 'On the Anatomy of the Blow-Fly, Musca vomitoria,' 18V'->, p. 14. 340 SEXUAL SELECTION. [Part 1L 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, JZeduvius per- sonatus 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, Homoptera. — Every one who has wandered in a tropical forest must have been astonished at the din made by the male Cicadse. 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 mile from the shore of Brazil ; and Captain Hancock says it can be heard at the distance of a mile. The Greeks formerly kept, and the Chinese now keep, these insects in cages for the sake of their song, so that it must be pleasing to the ears of some men.21 The Cicadidas usually sing during the day; while the Fulgoridse appear to be night-songsters. The sound, ac- cording to Landois,23 who has recently studied the subject, is produced by the vibration of the lips of the spiracles, which are set into motion bv a current of air emitted from the tracheae. It is increased by a wonderfully complex resounding apparatus, consisting of two cavities 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 male, and is never used for producing sound. With respect to the object of the music, Dr. Hartman, 21 Westwood, • Modern Class, of Insects,' vol. ii. p. 473. 22 These particulars are taken from Westwood's ' Modern Class, of Insects,' vol. ii. 1840, p. 422. See, also, on the Fulgoridae, Kirby aud Spence, ' Introduct.' vol. ii. p. 401. »3 « Zeitschrift fur wissenschaft. Zoolog.' B. xvii. 186V, s. 152-158. Chap. X.] HOMOPTERA. 341 in speaking of the cicada septemdechn 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 hun- dreds were around me, I observed the females coming around the drumming males." He adds : " This season (August, 1868) a dwarf pear-tree in my garden produced about fifty larvae of Clc. pruinosa; and I several times noticed the females to alight near a male while he was ut- tering his clanging notes." Fritz Muller writes to me from Southern Brazil that he has often listened to a musi- cal contest between two or three males of a Cicada, hav- ing a particularly loud voice, and seated at a considerable distance from each other. As soon as the first had fin- ished his song, a second immediately began ; and after lie had concluded, another began, and so on. As there is so much rivalry between the males, it is probable that the females not only discover 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 ornamental differences between the sexes of the Homoptera. Mr. Douglas informs me that there are three British species, in which the male is black or marked with black bands, while the females are pale-colored or obscure. Order, Orthoptera. — The males in the three saltatorial families belonging to this Order are remarkable for their musical powers, namely, the Achetidse or crickets, the Locustidse for which there is no exact equivalent name in English, and the Acridiidae or grasshoppers. The stridu- lation produced by some of the Locustidae is so loud that 24 1 am indebted- to Mr. Walsh for having sent me this extract- from a 'Journal of the Doings of Cicada septemdecim,' by Dr. Hartman. 342 SEXUAL SELECTION. [Part II. it can be heard during the night at the distance of a mile ; 25 and that made by certain species is not unmusical even' to the human ear, so that the Indians on the Ama- zons keep them hi wicker cages. All observers agree that the sounds serve either to call or excite the mute females. But it has been noticed26 that the male migratory locust of Russia (one of the Acridiidae), while coupled with the female, stridulates from anger or jealousy when ap- proached 'by another male. The house-cricket when sur- prised at night uses its voice to warn its fellows.27 In North America the Katy-did (Platyphyllum concavum, one of the Locustidse) is described 28 as mounting on the upper branches of a tree, and in the evening be- ginning his noisy babble, while rival notes issue from the neighboring trees, and the groves resound with the call of Katy-did -she -did the live-long night." Mr. Bates, in speaking of the European field-cricket (one of the Achetidae), says: "The male has been ob- served 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, while the success- ful musician caresses with his antennae the mate he has 25 L. Guilding, ' Transact. Linn. Soc.' vol. xv. p. 154. 26 Koppen, as quoted in the 'Zoological Record,' for 1867, p. 460. 27 Gilbert White, ' Nat. Hist, of Selborne,' vol. ii. 1825, p. 262. 18 Harris, 'Insects of New England,' 1842, p. 128. Fig. 10.— Gryllus campestris (from Lan- dois). Rteht-hand figure, under Bide of part of the wing-nervur?, much magnified, showing the teeth, st. Left-hand figure, upper surface of wing- cover, with the projecting, smooth ner- vure, r, across which the teeth (st) are scraped. Chap. X.] ORTHOPTERA. 343 won." 29 Dr. Scudder was able to excite one of these in-' sects to answer him, by rubbing on a lile with a quill.30 In both sexes a remarkable auditory apparatus has been discovered by Von [Siebold, situated in the front legs.31 In the three Families the sounds are differently pro- duced. In the males of the Achetidse both wing-covers have the same structure ; and this in the fi eld-cricket (Gryllus campestris, fig. 10) consists, as described by Landois,32 of from 131 to 138 sharp, transverse ridges or teeth (st) 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 resonance. In some .Species the wing-covers of ,^ie males are furnished at the base with a talc-like plate.33 I have here given a drawing (fig. 11) of the teeth on the under side of the FlG n.__ Teeth of nervure of another species of Gryllus, viz., ?0eSticu8G(from G. domestiCKS. Landois). In the Locustidse the opposite wing-covers differ in structure (fig. 12), and cannot, as in the last family, be in- differently nsed in a reversed manner. The left wing, which acts as the bow of the fiddle, lies over the right 29 • The Naturalist on the Amazons,' vol. i. 1 863, p 252. Mr. Bates gives a very interesting discussion on the gradations in the musical appa* ratus of the three families. See also Westwood, ' Modern Class.' vol. ii. pp. 445, 453. 30 ' Proc. Boston Soc. of Nat. Hist.' vol. xi. April, 1868. 31 ' Nouveau Manuel d'Anat. Comp.' (French translat.), torn. i. 1850, p. 567. 32 ' Zeitschrift fiir wissenschaft. Zoolog.' B. xvii. 1867, s. 117. 23 Westwood, ' Modern Class, of Insects,' vol. i. p. 440. 344 SEXUAL SELECTION. [Part II. wing which serves as the fiddle itself. One of the ner- vures (a) on the under surface of the former is finely ser- rated, and is scraped across the prominent nervures on the upper surface of the opposite or right wing. In our Brit- ish Phasgonura viridissima it appeared to me that the serrated, nervure is rubbed against the rounded hind corner of the opposite wing, the edge of which is thick- ened, colored brown, and very sharp. In the right wing, but not in the left, there is a little plate, as transparent as talc, surrounded by nervures, and called the speculum, In Ephippiger vitium, a member of this same family, we have a curious subordinate modification; for the wing- covers are greatly reduced in size, but " the posterior part of the pro-thorax is elevated into a kind of dome over the Fig. 12.— Chlorocoelus Tanana (from Bates), a. b. Lobes of opposite win^-coveis. Chap. X.] ORTHOPTERA. 345 wing-covers, and which has probably the effect of increas- ing the sound." 3* We thus see that the musical apparatus is more differ- entiated or specialized in the Locustidae, which includes, I believe, the most powerful performers in the Order, than in the Achetidae, in which both wing-covers have the same structure and the same function.36 Landois, however, detected in one of the Loci\stidae, namely, in Decticus, a short and narrow row of small teeth, mere rudiments, on the inferior surface of the right wing-cover, which under- lies the other and is never used as the bow. I observed the same rudimentary structure on the under side of the right wing-cover in Phasgonura viridissima. Hence we may with confidence infer that the Locustidae are de- scended from a form, in which, as in the existing Ache- tidae, both wing-covers had serrated nervures on the under surface, and could be indifferently used as the bow ; but that in the Locustidae the two wing-covers gradually be- came differentiated and perfected, on the principle of the division of labor, the one to act exclusively as the bow and the other as the fiddle. By what steps the more simple apparatus in the Achetidae originated, we do not know, but it is probable that the basal portions of the 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.88 A grating sound thus occasionally and ac- cidentally 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 having been continually preserved. . 34 Westwood, ' Modem Class, of Insects,' vol. i. p. 453. « Landois, ibid. s. 121, 122. 8e Mr. Walsh also informs me that he has noticed that the female of 346 SEXUAL SELECTION. [Part II. In the last and third Family, namely, the Acridiidse or grasshoppers, the stridulation is produced in a very different manner, and is not so shrill, according to Dr. Scudder as in the preceding Families. The inner surface of the femur (fig. 13, r) is furnished with a longitudinal row of minute, elegant, lancet-shaped, elastic teeth, from 85 to 93 in number;37 and these are scraped across the sharp, projecting nervures on the wing-covers, which are thus made to vibrate and resound. Harris38 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 designed to receive it, and then draws the leg briskly up and down. He does not play both fiddles together, but alternately first upon one and then on the other." Fig. 13.— Hind-leg of Stenobothrus pratorum: Tn Tv^m,. cr^pip<3 tLp h. A.IPIPX^EJTON" &J CO.. P«Mish«ra. 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