BEQUEST OF ARTHUR LYON GROSS PROFESSOR OF ENGLISH HISTORY TO THE UNIVERSITY OF MICHIGAN 1940 /-P # £ : y ^s^- •* sy*^t>^ frequently occurs in the negro. Cha*. I. Rudiments, 23 mentary condition, for they consist, with the exception of the basal one, of the centrum alone.53 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, a muscle which is so largely developed in many mammals. The spinal cord in man extends only as far downwards as the last dorsal or first lumbar vertebra; but a thread-like struc- ture (the filum terminate) runs down the axis of the sacral part of the spinal canal, and even along the back of the coccygeal bones. The upper part of this filament, as Prof. Turner informs, me, is undoubtedly homologous with the spinal cord • but the lower part apparently consists merely of the pia mater, or vascular investing membrane. 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 in- debted to Prof. Turner, shews how closely the os coccyx corre- sponds with the true tail in the lower animals : Luschka has recently discovered at the extremity of the coccygeal bones a very peculiar convoluted body, which is continuous with the middle sacral artery ; and this discovery led Krause and Meyer to examine the tail of a monkey (Macacus), and of a cat, in both of which they found a similarly convoluted body, though not at the extremity. The reproductive system offers various rudimentary struc- tures; but these differ in one important respect from the foregoing cases. Here we are not concerned with the vestige of a part which does not belong to the species in an efficient state, but with a part efficient in the one sex, and represented in the other by a mere rudiment. Nevertheless, the occurrence of such rudiments is as difficult to explain, on the belief of the separate creation of each species, as in the foregoing cases. Hereafter I shall have to recur to these rudiments, and shall shew that their presence generally depends merely on inheri- tance, that is, on parts acquired by one sex having been partially transmitted to the other. I will in this place only give some instances of such rudiments. It is well known that in the males of all mammals, including man, rudimentary mammae exist. These in several instances have become well developed, and have yielded a copious supply of milk. Their essential identity in the two sexes is likewise shewn by their occasional sympathetic enlargement in both during an attack of the a8 Owes, < On the Nature of Umbsty 1849, p. 114. 24 The Descent of Man, Part j measles. The vesicula prostatica, which has been observed in many male mammals, is now universally acknowledged to be the homologue of the female uterus, together with the con- nected passage. It is impossible to read Leuckart's able description of this organ, and his reasoning, without admitting the justness of his conclusion. This is especially clear in the case of those mammals in which the true female uterus bifurcates, for in the males of these the vesicula likewise bifurcates.64 Some other rudimentary structures belonging to the reproductive system might have been here adduced.55 The bearing of the three great classes of facts now given is unmistakeable. But it would be superfluous fully to recapitulate the line of argument given in detail in my ' Origin of Species,' The homological construction of the whole frame in the members of the same class is intelligible, if we admit their descent from a common progenitor, together with their subsequent adaptation to diversified conditions. On any other view, the similarity of pattern between the hand of a man or monkey, the foot horse, the flipper of a seal, the wing of a bat, &c, is utterly inexplicable.56 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 54 Leuckart, in Todd's * Cyclop, words) a mere metaphysical prin- o£ Anat/ 1849-52, vol. iv. p. 1415. ciple, namely, the preservation "in In man this organ is only from " its integrity of the mammalian three to six lines in length, but, " nature of the animal." In only a like so many other rudimentary few cases does he discuss rudiments, parts, it is variable in development and then only those parts which are as well as in other characters. partially rudimentary, such as the 55 See, on this subject, Owen, little hoofs of the pig and ox, which * Anatomy of Vertebrates/ vol. iii. do not touch the ground ; these he pp. 675, 676, 706. shews clearly to be of service to the 56 Prof. Bianconi, in a recently animal. It is unfortunate that he published work, illustrated by ad- did not consider such cases as the mirable engravings ('La Theorie minute teeth, which never cut Darwinienne et la creation dite in- through the jaw in the ox, or the dependante,' 1874), endeavours to mammae of male quadrupeds, or the show that homological structures, in wings of certain beetles, existing the above and other cases, can be under the soldered wing-covers, or fully explained on mechanical prin- the vestiges of the pistil and stamens ciples, in accordance with their uses, in various flowers, and many other No one has shewn so well, how ad- such cases. Although I greatly mirably such structures are adapted admire Prof. Bianconi's work, yet for their final purpose ; and this the belief now held by most natural- adaptation can, as I believe, be ists seems to me left unshaken, explained through natural selection, that homological structures are in- In considering the wing of a bat, he explicable on the principle of mere brings forward (p. 218) what appears adaptation. to me (to use Auguste Comte's Chap. J. Rudiments, 25 variations supervening a* a rafcher late embryonic period, and being inherited at a corresponding period, how it is that the embryos of wonderfully different forms should still retain, mors or less perfectly, the structure of their common progenitor. No other explanation has ever been given of the marvellous fact that the embryos of a man, dog, seal, bat, reptile, &c, can at first hardly be distinguished from each other. In order to understand the existence of rudimentary organs, we have only to suppose that a former progenitor possessed the parts in question in a perfect state, and that under changed habits of life they became greatly reduced, either from simple disuse, or through the natural selection of those individuals which were least encumbered with a superfluous part, aided by the other means previously in- dicated. Thus we can understand how it has come to pass that man and all other vertebrate animals have been constructed on the same general model, why they pass through the same early stages ot development, and why they retain certain rudiments in common. Consequently we ought frankly to admit their community of descent; to take any other view, is to admit that our own structure, and that of all the animals around us, is a mere snare laid to entrap our judgment. This conclusion is greatly strengthened, if we look to the members of the whole animal series, and consider the evidence derived from their affinities or classification, their geographical distribution and geolo- gical succession. It is only our natural prejudice, and that arrogance which made our forefathers declare that they were descended from demi-gods, which leads us to demur to this conclusion. But the time will before long come, when it will be thought wonderful that naturalists, who were well acquainted with the comparative structure and development of man, and other mammals, should have believed that each was the work of a separate act of creation. 26 The Descent of Man, Pax* 1 CHAPTEB a. Ok the Manner of Development of Man from some Lower Form. Variability of body and mind in man — Inheritance — Causes of variability — Laws of variation tne same in man as in the lower animals — Direct action of the conditions of life — Effects of the increased use and disuse of parts — Arrested development — Reversion — Correlated variation — Rate of increase — Checks to increase — Natural selection — Man the most dominant animal in the world — Importance of his corporeal structure — The causes which have led to his becoming erect — Consequent changes of structure — Decrease in size of the canine teethe — Increased size and altered shape of the skull — Nakedness — Absence of a tail — Defenceless condition of man. It is manifest that man is now subject to much variability. No two individuals of the same race are quite alike. We may compare millions of faces, and each will be distinct. There is an equally great amount of diversity in the proportions and dimensions of the various parts of the body ; the length of the legs being one of the most variable points.1 Although in some quarters of the world an elongated skull, and in other quarters a short skull prevails, yet there is great diversity of shape even within the limits of the same race, as with the aborigines of America and South Australia — the latter a race " probably as " pure and homogeneous in blood, customs, and language as any ** in existence " — and even with the inhabitants of so confined an area as the Sandwich Islands.2 An eminent dentist assures me that there is nearly as much diversity in the teeth as in the features. The chief arteries so frequently run in abnormal courses, that it has been found useful for surgical purposes to calculate from 1040 corpses how often each course prevails.3 The muscles are eminently variable: thus those of the foot were found by Prof. Turner4 not to be strictly alike in any two out of fifty bodies ; and in some the deviations were considerable, 1 'Investigations in Military and Huxley, in LyelPs 'Antiquity of Anthropolog. Statistics of American Man/ 1863, p. 87. On the Sand- Soldiers/ by B. A. Gould, 1869, p. wich Islanders, Prof. J. Wyman, 256. 'Observations on Crania,' Boston; 2 With respect to the « Cranial 1868, p. 18. forms of the American aborigines,', * * Anatomy of the Arteries," by Bee Dr. Ait ken Meigs in ' Proc. R. Quain. Preface, vol. i. 1844. Acad. Nat. Sci.' Philadelphia, May, 4 'Transact. Royal Soc. Ediiy 1868. On the Australians, see frcrgh,' vol. xxiv. pp. 175, 180. Uha*. II. Manner of Development 27 Ee adds, that the power of performing the appropriate move- ments must have been modified in accordance with the several deviations. Mr. J. Wood has recorded5 the occurrence of 295 muscular variations in thirty-six subjects, and in another set of the same number no less than 558 variations, those occurring on both sides of the body being only reckoned as one. In the last set, not one body out of the thirty-six was " found totally «< wanting in departures from the standard descriptions of the " muscular system given in anatpmical text books." A single body presented the extraordinary number of twenty-five distinct abnormalities. The same muscle sometimes varies in many ways: thus Prof. Macalister describes6 no less than twenty distinct variations in the palmaris accessorius. The famous old anatomist, Wolff,7 insists that the internal viscera are more variable than the external parts: Nulla parti- cular est qua non aliter et aliter in aliis se habeat liominibus. He has even written a treatise on the choice of typical examples of • the viscera for representation. A discussion on the beau-ideal of the liver, lungs, kidneys, &c, as of the human face divine, Bounds strange in our ears. The variability or diversity of the mental faculties in men of the same race, not to mention the greater differences between the men of distinct races, is so notorious that not a word need here be said. So it is with the lower animals. All who have had charge of menageries admit this fact, and we see it plainly in our dogs and other domestic animals. Brehm especially insists that each individual monkey of those which he kept tame in Africa had its own peculiar disposition and temper: he men- tions one baboon remarkable for its high intelligence ; and the keepers in the Zoological Gardens pointed out to me a monkey, belonging to the New World division, equally remarkable for intelligence. Eengger, also, insists on the diversity in the various mental characters of the monkeys of the same species which he kept in Paraguay; and this diversity, as he adds, is partly innate, and partly the result of the maimer in which they have been treated or educated.8 I have elsewhere9 so fully discussed the subject of Inheritance, that I need here add hardly anything. A greater number of 5 'Pioc. Royal Soc* 1867, p. 8 Biehm, * Thierleben/ B. i. a. 544 ; also 1868, pp. 483, 524. There 58, 87. Rengger, ' Saugethiere toe is a previous paoer, 1866, p. 229. Paraguay/ s. 57. 6 ' Proc. R. Irish Academy,' vol. • * Variation of Animals and x. 1868, p! 141. Fiants under Domestication,' vol : 'Act. Acad. St. Petersburg/ ii. chap. sa. 1778, part ii. p. 217 28 The Descent of Man* Tart 1, facts have been collected with respect to th« transmission of the most trifling, as well as of the most important characters in man, than in any of the lower animals; though the facts are copious enough with respect to the latter. So in regard to mental qualities, their transmission is manifest in our dogs, horses, and other domestic animals. Besides special tastes and habits, general intelligence, courage, bad and good temper, &c, are certainly transmitted. With man we see similar facts in almost every family; and we now know, through the admirable labours of Mr. Galton,10that genius which implies a wonderfully complex combination of high faculties, tends to be inherited; and, on the other hand, it is too certain that insanity and deteri- orated mental powers likewise run in families. With respect to the causes of variability, we are in all cases very ignorant; but we can see that in man as in the lower animals, they stand in some relation to the conditions to which • each species has been exposed, during several generations. Domesticated animals vary more than those in a state of nature ; and this is apparently due to the diversified and changing nature of the conditions to which they have been subjected. In this respect the different races of man resemble domesticated animals, and so do the individuals of the same race, when inhabiting a very wide area, like that of America. We see the influence of diversified conditions in the more civilised nations; for the members belonging to different grades of rank, and following different occupations, present a greater range of character than do the members of barbarous nations. But the uniformity of savages has often been exaggerated, and in some cases can hardly be said to exist.11 It is, nevertheless, an error to speak of man, even if we look only to the conditions to which he has been exposed, as " far more domesticated "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 a wide range. In another and much more important respect, man differs widely from any strictly domesticated animal ; for his breeding has never long been controlled, either by methodical or unconscious selection. No race or body of men has been so 10 * Hewditwy Genius : an In- " man had an oval visage with fine quiry into :t3 Laws and Conse- " features, and another was quite quences/ 1869. " Mongolian in breadth and pro- 11 Mr. Bates remarks (' The Natu- ** minence of cheek, spread of nos- ralist on the Amazons/ 1863, vol. ii. " trils, and obliquity of eyes." p. 159), with respect to the Indians 12 Blumenbach, 'Treatises on An- of the same South American tribe, thropolog.* Eng. translal., 18 ?5, p. a to two of them were at all similar 205. u in the shape of the head j on? Chap. II. Manner of Development 29 completely subjugated by other men, as that certain individuals should be preserved, and thus unconsciously selected, from some- how excelling in utility to their masters. Nor have certain male and female individuals been intentionally picked out and matched, except in the well-known case of the Prussian grena- diers ; and in this case man obeyed, as might have been ex- pected, the law of methodical selection ; for it is asserted that many tall men were reared in the villages inhabited by the grenadiers and their tall wives. In Sparta, also, a form of selec- tion was followed, for it was enacted that all children should be examined shortly after birth; the well-formed and vigorous being preserved, the others left to perish.13 If we consider all the races of man as forming a single species, his range is enormous ; but some separate races, as the Americans and Polynesians, have very wide ranges. It is a well-known law that widely-ranging species are much more variable than species with restricted ranges ; and the variability of man may with more truth be compared with that of widely-ranging species, than with that of domesticated animals. Not only does variability appear to bo induced in man and the lower animals by the same general causes, but in both the same parts of the body are affected in a closely analogous manner. This, has been proved in such full detail by Godron and 13 Mitford's ' History of Greece/ vigour of their children. The Gre- vol. i. p. 282. It appears also from cian poet, Theognis, who lived 550 a passage in Xenophon's ' Memora- B.C., clearly saw how important bilia,' B. ii. 4 (to which my atten- selection, if carefully applied, would tion has been called by the Rev. be for the improvement of mankind. J. N. Hoare), that it was a well He saw, likewise, that wealth often recognised principle with the Greeks, checks the proper action of sezua] that men ought to select their wives selection. He thus writes : with a view to the health and " With kine and horses, Kurnus ! we proceed By reasonable rules, and choose a breed For profit and increase, at any price ; Of a sound stock, without defect or vice. But, in the daily matches that we make, The price is everything : for money's sake, Men marry : women are in marriage given The churl or ruffian, that in wealth has thriven, May match his offspring with the proudest race : Thus everything is mix'd, noble and base ! If then in outward manner, form, and mind, You find us a degraded, motley kind, Wonder no more, my friend I the cause is plain, And to lament the consequence is vain.'* (The Weeks of J. Hookham Frere, vol. ii. 1872, p. 334.) 30 The Descent of Man. Tax? L Quatrefages, that I need here only refer to their works.1,1 Mon- strosities, which graduate into slight variations, are likewise so similar in man and the lower animals, that the same classification and the same terms can be used for both, as has been shewn by Isidore Geoffroy St.-Hilaire.16 In my work on the variation of domestic animals, I have attempted to arrange in a rude fashion the laws of variation under the following heads : — The direct and definite action of changed conditions, as exhibited by all or nearly all the individuals of the same species, varying in the same manner Under the same circumstances. The effects of the long-continued use or disuse of parts. The cohesion of homologous parts. The variability of multiple parts. Compensation of growth ; but of this law I have found no good instance in the case of man. The effects of the mechanical pressure of one part on another ; as of the pelvis on the cranium of the infant in the womb. Arrests of development, leading to the diminution or suppression of parts. The reappearance of long-lost characters through reversion. And lastly, correlated variation. All these so-called laws apply equally to man and the lower animals ; and most of them even to plants. It would be superfluous here to discuss all of them ;10 but several are so important, that they must be treated at con- siderable length. The direct and definite action of changed conditions. — This is a most perplexing subject. It cannot be denied that changed con- ditions produce some, and occasionally a considerable effect, on organisms of all kinds ; and it seems at first probable that if sufficient time were allowed this would be the invariable result. But I have failed to obtain clear evidence in favour of this con- clusion ; and valid reasons may be urged on the other side, at least as far as the innumerable structures are concerned, which are adapted for special ends. There can, however, be no doubt that changed conditions induce an almost indefinite amount of fluctuating variability, by which the whole organisation is rend- ered in some degree plastic. In the United States, above 1,000,000 soldiers, who served in the late war, were measured, and the States in which they were 14 Godron, *De l'Espece,' 1859, 16 I have fully discussed these tcm. ii. livre 3. Quatrefages, * Unite laws in my * Variation of Animals de l'Espece Humaine,' 1861. Also and Plants under Domestication,' Lectures on Anthropology, given in vol. ii. chap. xxii. and xxiii. M. J. the *■ Revue des Cours Scientifiques,' P. Durand has lately (1868) pub- 1866-1868. lished a valuable essay * De l'ln- 15 * Hist. Ge*n. a> Part, des Ano- fluence des Milieux,' &c. He lays malies de rOrgamsation,' in three much stress, in the case of plar is, on volumes, torn. i. 1832. the nature of the soil. Chap. II. Manner of Development 31 born and reared were recorded.17 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 influence on the stature/' Tor instance, it is established, " that residence in the Western States, during the " years of growth, tends to produce increase of stature." On the other hand, it is certain that with sailors, their life delays growth, as shewn " by the great difference between the statures of soldiers " and sailors at the ages of seventeen and eighteen years." Mr. B. A. Gould endeavoured to ascertain the nature of the influences which thus act on stature ; but he arrived only at negative results, namely, that they did not relate to climate, the elevation of the ) land, soil, nor even " in any controlling degree " to the abundance I or the need of the comforts of life. This latter conclusion is directly opposed to that arrived at by Villerme, from the statistics of the height of the conscripts in different parts of France. When we compare the differences in stature between the Polynesian chiefs and the lower orders within the same islands, or between the inhabitants of the fertile volcanic and iow barren coral islands of the same ocean,18 or again between the Fuegians on the eastern and western shores of their country, where the means of subsis- tence are very different, it is scarcely possible to avoid the con- clusion that better food and greater comfort do influence stature. But the preceding statements shew how difficult it is to arrive at any precise result. Dr. Beddoe has lately proved that, with the inhabitants of Britain, residence in towns and certain occupa- tions have a deteriorating influence on height ; and he infers that the result is to a certain extent inherited, as is likewise the case in the United States. Dr. Beddoe further believes that wherever a " race attains its maximum of physical development, it rises " highest in energy and moral vigour." 19 Whether external conditions produce any other direct effect t on man is not known. It might have been expected that dif- ferences of climate would have had a marked influence, in as much as the lungs and kidneys are brought into activity under a low 17 ' Investigations in Military and 289. There is also a remarkable Anthrop. Statistics,' &c. 1869, by difference in appearance between B. A. Gould, p. 93, 107, 126, 131, the closely-allied Hindoos inhabiting 134. the Upper Ganges and Bengal; see 18 For the Polynesians, see Prich- Elphinstone's ' History of India/ vol. ard's < Physical Hkt. of Mankind/ i. p. 324. Tol. v. 1847, p. 145, 283. Also 19 'Memoir^ Anthropolog. Soc. fjtodron, * Be l'Espfcce/ torn. ii. p. vol. iii. 1867-69, pp. 561, 565, 567, 32 The Descent of Man. Pabt 1 temperature, and the liver and skin under a high one.20 It was formerly thought that the colour of the skin and the character of the hair were determined by light or heat ; and although it can hardly be denied that some effect is thus produced, almost all observers now agree that the effect has been very small, even after exposure during many ages. But this subject will be more properly discussed when we treat of the different races of man- kind. With our domestic animals there are grounds for believing that cold and damp directly affect the growth of the hair ; but I have not met with any evidence on this head in the case of man. Effects of the 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 to act from disease, the other increases in size, and does double work. Bones increase not only in thickness, but in length, from carrying a greater weight.21 Different occupations, habitually followed, lead to changed proportions in various parts of the body. Thus it was ascertained by the United States Commission M that the legs of the sailors employed in the late war were longer by 0*217 of an inch, than those of the soldiers, though the sailors were on an average shorter men; whilst their arms were shorter by 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 supporting weights. With sailors, the girth of the neck and the depth of the instep are greater, whilst the circumference of the chest, waist, and hips is less, than in soldiers. Whether the several foregoing modifications would become hereditary, if the same habits of life were followed during many generations, is not known, but it is probable. Bengger 123 attri- butes the thin legs and thick arms of the Payaguas Indians to 20 Dr. Brakenridge, * Theory of Dr. Jaeger, "Ueber das L'angen- Diathesis,' 'Medical Times/ June 19 wachsthum der Knochen," * Jena- and July 17, 1869. ischen Zeitschrift/ B. v. Heft i. 21 I have given authorities for 22 ' Investigations/ &c. By B. A* these several statements in my Gould, 1869, "p. 288. * Variation of Animals Tinder Do- 2S 'S'augethiere von Paraguay mestication/ vol. ii. pp. 297-300. 1830, s. 4. Chap. II, Manner of Development 33 successive generations having passed nearly their whole lives in canoes, with their lower extremities motionless. Other writers have come to a similar conclusion in analogous cases. According to Cranz,124 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 labourers are at birth larger than those of the gentry.26 From the correlation which exists, at least in some cases,26 between the development of the extremities and of the jaws, it is possible that in those classes which do not labour much with their hands and feet, the jaws would be reduced in size from this cause. That they are generally smaller in refined and civilised men than in hard-working men or savages, is certain. But with savages, as Mr. Herbert Spencer ^ has remarked, the greater use of the jaws in chewing coarse, uncooked food, would act in a direct manner on the' masticatory muscles, and on the bones to which they are attached. In infants, long before birth, the skin on the soles of the feet is thicker than on any other part of the body ; 28 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 engravers are liable to be short-sighted, whilst men living much out of doors, and especially savages, are generally long-sighted.29 Short- sight and long-sight certainly tend to be inherited.30 The inferiority of Europeans, in comparison with savages, in eye- sight and in the other senses, is no doubt the accumulated and transmitted effect of lessened use during many generations ; for Eengger31 states that he has repeatedly observed Europeans, 24 * History of Greenland/ Eng. (' Sanitary Memoirs of the War of translat. 1767, vol. i. p. 230. the Rebellion/ 1869, p. 530), has 25 * Intermarriage.' By Alex, proved this to be the case ; and he Walker, 1838, p. 377. accounts for it by the ordinary 28 • The Variation of Animals range of vision in sailors being " re- under Domestication, vol. i. p. 173. " stricted to the length of the vessel 27 * Principles of Biology/ vol. i. " and the height of the masts." p. 455. 30 * The Variation of Animals 28 Paget, ' Lectures on Surgical under Domestication/ vol. i. p. 8. Pathology/ vol. ii. 1853, p. 209. 31 * S'augethiere von Paraguay,' 28 It is a singular and unex- s. 8, 10. I have had good opportuni- pected fact that sailors are inferior ties for observing the extraordinary to landsmen in tjheir mean distanoe power of eyesight in the Fuegians. of distinct vision. Dr. B. A. Gould See also Lawrence ('Lectures ou » 34 The Descent of Alan. pji bt X who had been brought up and spent their whole lives with the wild Indians, who nevertheless did not equal them in the sharp- ness of their senses. The same 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 probably indicates a corresponding difference in the dimen- sions of the organs themselves. Blumenbach has also remarked on the large size of the nasal cavities in the skulls of the American aborigines, and connects this fact with their remarkably acute power of smell. The Mongolians of the plains of Northern Asia, according to Pallas, have wonderfully perfect senses ; and Prichard believes that the great breadth of their skulls across the zygomas follows from their highly-developed sense-organs.32 The Quechua Indians inhabit the lofty plateaux of Peru ; and Alcide d'Orbigny states83 that, from continually breathing a highly rarefied atmosphere, they have acquired chests and lungs of extraordinary dimensions. The cells, also, of the lungs are larger and more numerous than in Europeans. These observa- tions have been doubted ; but Mr. D. Forbes carefully measured many Aymaras, an allied race, living at the height of between 10,000 and 15,000 feet; and he informs me84 that they differ conspicuously from the men of all other races seen by him in the circumference and length of their bodies. In his table of measurements, the stature of each man is taken at 1000, and the other measurements are reduced to this standard. It is here seen that the extended arms of the Aymaras are shorter than those of Europeans, and much shorter than those of Negroes. The legs are likewise shorter ; and they present this remarkable peculiarity, that in every Aymara measured, the femur is actually shorter than the tibia. On an average, the length of the femur to that of the tibia is as 211 to 252 ; whilst in two Europeans, measured at the same time, the femora to the tibiae were as 244 to 230 ; and in three Negroes as 258 to 241. The humerus is likewise shorter relatively to the forearm. This shortening of that part of the limb which is nearest to the body, appears to be, as suggested to me by Mr. Forbes, a case of compensation in Physiology/ &c, 1822, p. 404) on bach, vol. i. 1851, p. 311; for the this same subject. M. Giraud-Teulon statement by Pallas, vol. iv. 1844, has recently collected (* Revue des p. 407. Cours Scientifiques,* 1870, p. 625) ™ Quoted by Prichard, * Re- ft large and valuable body of evidence searches into the Phys. Hist, of Man- proving that the cause of short- kind/ vol. v. p. 463. Bight, " (Test le travail assidu, de 34 Mr. Forbes' valuable paper i* prci." now published in the * Journal of ** Prichard, ' Phys. Hist, of Man- the Ethnological Sec. of London, kind/ on the authority of Blumen- new series, vol. ii 1870, p. 103. CaA*. II. , Manner of Development 33 relation with the greatly increased length of the trunk. The Aymaras present some other singular points of structure, foi instance, the very small projection of the heel. These men are so thoroughly acclimatised to their cold and lofty abode, that when formerly carried down by the Spaniards to the low eastern plains, and when now tempted down by high wages to the gold-washings, they suffer a frightful rate of mor- tality. Nevertheless Mr. Forbes found a few pure families which had survived during two generations : and he observed that they still inherited their characteristic peculiarities. But it was manifest, even without measurement, that these 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 ; whilst their femora had become somewhat lengthened, as had their tibiae, although in a less degree. The actual measurements may be seen by consulting Mr. Forbes's memoir. From these observations, there can, I think, be no doubt that residence during many generations at a great elevation tends, both directly and indirectly, to induce inherited modifications in the proportions of the body.35 Although man may not have been much modified during the latter stages of his existence through the increased or de- creased use of parts, the facts now given shew that his liability in this respect has not been lost ; and we positively know that the same law holds good with the lower animals. Consequently we • may infer that when at a remote epoch the progenitors of man were in a transitional state, and were changing from quadrupeds * into bipeds, natural selection would probably have been greatly aided by the inherited effects of the increased or diminished use of the different parts of the body. Arrests of Development. — There is a difference between arrested development and arrested growth, for parts in the former state continue to grow whilst still retaining their early condition. Various monstrosities come under this head ; and some, as a cleft-palate, are known to be occasionally inherited. It will suffice for our purpose to refer to the arrested brain-development of microcephalous idiots, as described in Vogt's memoir.86 Their skulls are smaller, and the convolutions of the brain are less complex than in normal men. The frontal sinus, or the 83 Dr. Wilckens (' Landwirth- regions, have their frames modified, schaft. Wochenblatt,' No. 10, 1869) 3e 'Memoire sur les Microce- has lately published an interesting phales,' 1867, pp. 50, 125, 169, 171, Essay shewing how domestic ani 184-193. mala, which live in mountainous D 2 36 The Descent of Man, Past L projection over the eye-brows, is largely developed, and the jaws are prognathous to an " effrayant" degree ; so that these idiots somewhat resemble the lower types of mankind. Their in- telligence, and most of their mental faculties, are extremely feeble. They cannot acquire the power of speech, and are wholly incapable of prolonged attention, but are much given to imitation. They are strong and remarkably active, continually gamboling and jumping about, and making grimaces. They often ascend stairs on all-fours; and are curiously fond of climling up furniture or trees. "We are thus reminded of the delight shewn by almost all boys in climbing trees; and this again reminds us how lambs and kids, originally alpine animals, delight to frisk on any hillock, however small. Idiots also resemble the lower animals in some other respects; thus several cases are recorded of their carefully smelling every mouthful of food before eating it. One idiot is described as often using his mouth in aid of his hands, whilst hunting for lice. They are often filthy in their habits, and have no sense of decency ; and several cases have been published of their bodies being re- markably hairy.37 Beversion. — Many of the cases to be here given, might have been introduced under the last heading. When a structure is arrested in its development, but still continues growing, until it closely resembles a corresponding structure in some lower and adult member of the same group, it may in one sense be considered as a case of reversion. The lower members in a group give us some idea how the common progenitor was probably constructed ; and it is hardly credible that a complex part, arrested at an early phase of embryonic development, should go on growing so as ultimately to perform its proper function, unless it had acquired such power during some 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.38 There are other cases which come 37 Prof. Laycock sums up the pp. 46-51. Pinel has also given a character of brute-like idiots by striking case of hairiness in an calling them theroid ; * Journal of idiot. Mental Science,* July 1863. Dr. 38 In my * Variation of Animals Scott (' The Deaf and Dumb/ 2nd under Domestication * (vol. ii. p. 57), edit., 1870, p. 10) has often ob- I attributed the not very rare cases served the imbecile smelling their of supernumerary mammae in women food. See, on this same subject, to reversion. I was led to this as a and on the hairiness of idiots, Dr. probable conclusion, by the additional Mandsley, < Body and Mind,' 1870, mammae being generally plaosd Chap. II. Manner of Development 37 more strictly under our present head of reversion. Cortain structures, regularly occurring in the lower members of the group 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 mam- mae. But 1 now find (see, for in- stance, Prof. Preyer, * Der Kanapf um das Dasein,' 1869, s. 45) that mammas erraticce occur in oUielt situations, as -on the back, in the\ armpit, and on the thigh ; the mammae in this latter instance ha ring given so much milk that the child was thus nourished. The pro- bability that the additional mamma) are due to reversion is i;hus much weakened ; nevertheless, it still seems to me probable, because two pairs are often found symmetrically on the breast ; and of this I myself have received information in several cases. It is well known that some Lemurs normally have two pairs of mammae on the breast. Five cases have been recorded of the presence of more than a pair of mammae (of course rudimentary) in the male sex of mankind ; see * Journal of Anat. and Physiology,' 1872, p. 56, for a case given by Dr. Handyside, in which two brothers exhibited this peculiarity ; see also a paper by Dr. Barteis, in 'Reichert's and du Bois Reymond's Archiv./ 1872, p. 304. In one of the cases alluded to by Dr. Barteis, a man bore five mammas, one being medial and placed above the navel; Meckel von Hemsbach thinks that this latter case is illustrated by a medial mamma occurring in certain Cheiroptera. On the whole, we may well doubt if additional mammae would ever have been developed in both sexes of mankind, had not his early progenitors been provided with more than a single pair. In the above work (vol. ii. p. 12), I also attributed, though with much hesitation, the frequent cases of polydactylism in men and various animals to reversion. I was partly led to this through Prof. Owen*s statement, that some of the Ichthy- opterygia possess more than five digits, and therefore, as I supposed, had retained a primordial condition ; but Prof. Gegenbaur ('Jenaischen Zeitschrift,' B. v. Heft 3, s. 341), disputes Owen's conclusion. On the other hand, according to the opinion lately advanced by Dr. Giinther, on the paddle of Ceratodus, which is provided with articulated bony rays on both sides of a central chain or bones, there seems no great difficulty in admitting that six or more digits on one side, or on both sides, might reappear through reversion. I am informed by Dr. Zouteveen that there is a case on record of a man having twenty-four fingers and twenty-four toes ! I was chiefly led to the conclusion that the presence of supernumerary digits might be due to reversion from the fact that such digits, not only are strongly in- herited, but, as I then believed, had the power of regrowth after ampu- tation, like the normal digits of the lower vertebrata. But I have ex- plained in the Second Edition of my Variation under Domestication why I now place little reliance on the recorded cases of such regrowth. Nevertheless it deserves notice, in as much as arrested development and reversion are intimately related processes ; that various structures in an embryonic or arrested con- dition, such as a cleft palate, bifid uterus, &c, are frequently accom- panied by polydactylism. This has been strongly insisted on by Meckel and Isidore Geoffroy St.-Hilaire. But at present it is the safest course to give up altogether the idea thnt there is any relation between the development of supernumerary di- gits and reversion to some lowlf crganised progenia of man. $$ The Descent of Man. Part I, to which man belongs, occasionally make their appearance in him, though not found in the normal human embryo; or, it normally present in the human embryo, they become abnormally developed, although in a manner which is. normal in the lower members of the group. These remarks will be rendered clearer by the following illustrations. In various mammals the uterus graduates from a double organ with two distinct orifices and two passages, as in the marsupials, into a single organ, which is in no way double except from having a slight internal fold, as in the higher apes and man. The rodents exhibit a perfect series of gradations between these two extreme states. In all mammals the uterus is developed from two simple primitive tubes, the inferior portions of 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 ununited. 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 in animals as high up in the scale as the lower apes and lemurs. Now in women, anomalous cases are not very infrequent, in which the mature uterus is furnished with cornua, or is partially divided into two organs; and such cases, according to Owen, repeat "the grade of concentrative development," attained by certain rodents. Here perhaps we have an instance of a simple arrest of embryonic development, with subsequent growth and perfect functional development ; for either side of the partially double uterus is capable of performing the proper office of gestation. In other and rarer cases, two distinct uterine cavities are formed, each having its proper orifice and passage.39 No such stage is passed through during the ordinary development of the embryo ; and it is difficult to believe, though perhaps not im- possible, that the two simple, minute, primitive tubes should know how (if such an expression may be used) to grow into two 39 See Dr. A. Farre's well-known brates/ vol. iii., 1868, p. 687. Pro- article in the * Cyclopaedia of Ana- fessor Turner in 'Edinburgh Meli- tomy and Fhysioiogy,' vol. v. 1859, c«1 Journal/ February 1865. , 642, Owen, ' Anatomy of Verle- Chap. II. Manner of Development. 39 distinct uteri, each with a well-constructed orifice and passage, and each furnished with numerous muscles, nerves, glands and vessels, if they had not formerly passed through a similar course of development, as in the case of existing marsupials. No ono will pretend that so perfect a structure as the abnormal double uterus in woman could be the result of mere chance. But the principle of reversion, by which a long-lost structure is called back into existence, might serve as the guide for its full develop- ment, even after the lapse of an enormous interval of time. Professor Canestrini, after discussing the foregoing and various analogous cases, arrives at the same conclusion as that just given. He adduces another instance, in the case of the malar bone,40 which, in some of the Quadrumana and other mammals, normally consists of two portions. This is its condition in the human foetus when two months old ; and through arrested develop- ment, it sometimes remains thus in man when adult, more especially in the lower prognathous races. Hence Canestrini concludes that some ancient progenitor of man must have had this bone normally divided into two portions, which afterwards became 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 separated by a distinct suture. This suture occasionally persists more or less distinctly in man after maturity ; and more frequently in ancient than in recent crania, especially, as Canestrini has observed, in those exhumed from the Drift, and belonging to the brachyce- phalic typo. 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 i0 < Annuario della Soc. dei Natu- tected in about two per cent, of ralisti in Modena/ 1867, p. 83. adult skulls; he also remarks that Prof. Canestrini gives extracts on it more frequently occurs in pro- tnis subject from various authorities, gnathous skulls, not of the Aryan Laurillard remarks, that as he has race, than in others. See also G. found a complete similarity in the Delorenzi on the same subject ; * Tre form, proportions, and connection of nuovi casi d' an om alia dell'osso, the two malar bones in several malare/ Torino, 1872. Also, E. human subjects and in certain apes, Morselli, * Sopra una rara anomalia he cannot consider this disposition dell* osso malare/ Modena, 1872. ©f the parts as simply accidental. Still more recently Gruber has Another paper on this same anomaly written a pamphlet on the division has been published by Dr. Saviotti of this bone. 1 give these leferencea in the ' Gazzetta delle Cliniche/ because a reviewer, without any Turin, 1871, where he says that grounds or scruples, has thrown traces ef the division may be de- doubts or. my statements. 40 The Descent of Man. P^kf I, greater distance in the long line of descent from their early semi- fmman progenitors. Various other anomalies in man, more or less analogous to the foregoing, have been advanced by different authors, as cases of reversion ; but these seem not a little doubtful, for we have to descend extremely low in the mammalian series, before we find such structures normally present.41 In man, the canine teeth are perfectly efficient instruments for mastication. But their true canine character, as Owen42 re- marks, " is indicated by the conical form of the crown, which " terminates in an obtuse point, is convex outward and flat or " sub-concave within, at the base of which surface there is a " feeble prominence. The conical form is best expressed in the " 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 Hackel43 observes, with the canine teeth projecting considerably beyond the others in the same manner as in the anthropomorphous apes, but in a less degree. In these cases, open spaces between the teeth in the one jaw are left for the reception of the canines of the opposite jaw. An interspace of this kind in a Kaffir skull, figured by Wagner, is surprisingly wide.44 Considering how few are the ancient skulls which have been examined, compared to recent skulls, it is an interesting fact that in at least three cases the canines project largely; and in the Nauletto jaw they are spoken of as enormous.45 41 A whole series of cases is given if in any way serviceable, for in- by Isid. Gebffroy St.-Hilaire, * Hist, stance, in shortening and simplifying des Anomalies/ torn. iii. p. 437. the course of development ? Ard A reviewer (' Journal of Anat. and again, why should not injurious ab- Physiology/ 1871, p. 366) blames normalities, such as atrophied or hy- me much for not having discussed pertrophied parts, which have no the numerous cases, which have relation to a former state of exist- been recorded, of various parts ar- ence, occur at an early period, as rested in their development. He well as during maturity ? says that, according to my theory, ** * Anatomy of Vertebrates,* vol. " every transient condition of an iii. 1868, p. 323. " organ, during its development, is 43 *Generelle Morphologic/ 1866, ** not only a means to an end, but B. ii. s. civ. " once was an end in itself." This *4 Carl Vogt's * Lectures on Man,* does not seem to me necessarily to Eng. translat. 1864, p. 151. hold good. Why should not varia- 45 C. Carter Blake, on a jaw tions occur during an early period from La Naulette, i Anthropolog. of development, having no relation Review/ 1867, p. 295. Schaaff- 1,0 reversion; yet such variations hausen, ibid- 1868, p. 426. might be preserved and accumulated, Chap. II. Maimer of Development. 41 Of the anthropomorphous apes the males alone have their canines fully developed ; but in the female gorilla, and in a less degree in the female orang, these teeth project considerably beyond the others; therefore the fact, of which I have been assured, that women sometimes have considerably projecting canines, is no serious objection to the belief that their occasional great development in man is a case of reversion to an ape-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 forefathers haviDg been pro- vided with these formidable weapons, will probably reveal, by sneering, the line of his descent. For though he no longer intends, nor has the power, to use these teeth as weapons, he will unconsciously retract his " snarling muscles" (thus named by Sir C. Bell),46 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 Vlacovich47 examined forty male subjects, and found a muscle, called by him the ischio-pubic, in nineteen of them ; in three others there was a ligament which represented this muscle; and in the remaining eighteen no trace of it. In only two out of thirty female subjects was this muscle developed on both sides, but in three others the rudimentary ligament was present. This muscle, therefore, appears to be much more common in the male than in the female sex ; and on the belief in the descent of man from some lower form, the fact is intelligible ; for it has been detected in several of the lower animals, and in all of these it serves exclusively to aid the male in the act of reproduction. Mr. J. Wood, in his valuable series of papers,48 has minutely described a vast number of muscular variations in man, which resemble normal structures in the lower animals. The muscles « « The Anatomy of Expression/ pp. 241, 242 ; vol. xv. 1867, p. 544 ; 1844, pp. 110, 131. t vol. xvi. 1868, p. 524. I may here 47 Quoted by Prof. Canestrini in add that Dr. Murie and Mr. St. the 'Annuario/ &c, 1867, p. 90. George Mivart have shewn in their 48 These papers deserve careful Memoir on the Lemuroidea (' Tran- study by any one who desires to sact. Zoolog. Soc* vol. vii. 1869, learn how frequently our muscles p. 96), how extraordinarily variable rary, and in varying come to re- some of the muscles are in these semble those of the Quadrumana. animals, the lowest members of the The following references relate to Primates. Gradations, also, in the the few points touched on in my muscles leading to structures found text : * Proc. Royal Soc. vol. xiv. in animals still lower in the scale, 1865, pp. 379-384; vol. xv. 1866, ve numerous in the Lemuroidea, 42 TJie Descent of Man. Faet I, which closely resemble those regularly present in our nearest allies, the Quadrumana, are too numerous to be here even specified. In a single male subject, having a strong bodily frame, and well-formed skull, no less than seven muscular varia- tions were observed, all of which plainly represented muscles proper to various kinds of apes. This man, for instance, had on both sides of his neck a true and powerful " levator claviculce" such as is found in all kinds of apes, and which is said to occur in about one out of sixty human subjects.49 Again, this man had " a special abductor of the metatarsal bone of the fifth " digit, such as Professor Huxley and Mr. Flower have shewn " to exist uniformly in the higher and lower apes." I will give only two additional cases; the acromio-basilar muscle is found m all mammals below man, and seems to be correlated with a quadrupedal gait,60 and it occurs in about one out of sixty human subjects. In the lower extremities Mr. Bradley 51 found an abductor ossis metatarsi quinti in both feet of man ; this muscle had not up to that time been recorded in mankind, but is always present in the anthropomorphous apes. The muscles of the hands and arms — parts which are so eminently characteristic of man— are extremely liable to vary, so as to resemble the corresponding muscles in the lower animals.62 Such resem- blances are either perfect or imperfect; yet in the latter case they are manifestly of a transitional nature. Certain variations are more common in man, and others In woman, without our being able to assign any reason. Mr. Wood, after describing numerous variations, makes the following pregnant remark. " Notable departures from the ordinary type of the muscular " structures run in grooves or directions, which must be taken " to indicate some unknown factor, of much importance to a " comprehensive knowledge of general and scientific anatomy .,,6S 49 See also Prof. Macalister in able case of variation in the human ' Proc. R. Irish Academy,* vol. x. fiexor pollicis longus, adds, *< This. 1868, p. 124. " remarkable example shews that 50 Mr. Champneys in ' Journal of " man may sometimes possess the Anat. and Phys/ Nov., 1871, p. 178. " arrangement of tendons of thumb 51 ' Journal of Anat. and Phys.' " and fingers characteristic of the May, 1872, p. 421. "macaque; but whether such a 53 Prof. Macalister (ibid. p. 121) " case should be regarded as a has tabulated his observations, and " macaque passing upwards into a finds that muscular abnormalities " man, or a man passing downwards are most frequent in the fore-arms, " into a macaque, or as a congenita] cecondly, in the face, thirdly, in the " freak of nature, I cannot under- foot, &c. " take to say." It is satisfactory a* The Rev. Dr. Haughton, after to hear so capable an anatomist, giving ('Proc. R. Irish Academy,' and so embittered an opponent of June 27, 1864, p. 715) a remark- evolutionism, admitting even the Chap. II. Manner of Development. 43. That this unknown factor is reversion to a former state of existence may be admitted as in the highest degree probable M It is quite incredible that a man should through mere accident abnormally resemble certain apes in no less than seven of his muscles, if there had been no genetic connection between them. On the other hand, if man is descended from some ape-like creature, no valid reason can be assigned why certain muscles should not suddenly reappear after an interval of many thou- sand generations, in the same manner as with horses, asses, and mules, dark-coloured stripes suddenly reappear on the legs, and shoulders, after an interval of hundreds, or more probably of thousands of generations. These various cases of reversion are so closely related to those of rudimentary Organs given in the first chapter, that many of them might have been indifferently introduced either there or here. Thus a human uterus furnished with cornua may be said to represent, in a rudimentary condition, the same organ in its normal state in certain mammals. Some parts which are rudi- mentary in man, as the os coccyx in both sexes, and the mammas in the male sex, are always present; whilst others, such as the supracondyloid foramen, only occasionally appear, and therefore might have been introduced under the head of reversion. These several reversionary structures, as well as the strictly rudi- mentary ones, reveal the descent of man from some lower form in an unmistakable manner. Correlated Variation, A-In man, as in the lower animals, many structures are so intimately related, that when one part varies so does another, without our being able, in most cases, to assign any reason. We cannot ¥say whether the one part governs the other, or whether both are governed by some earlier developed possibility of either of his first pro- closely the variations resemble the positions. Prof. Macalister has also normal muscles of the lower ani- described (* Proc. R. Irish Acad.* mals. He sums up by remarking, vol. x. 1864, p. 138) variations in " It will be enough for my purpose the flexor pollicis longus, remarkable " if I have succeeded in shewing from their relations to the same " the more important forms which, muscle in the Quadrumana. " when occurring as varieties in the 54 Since the first edition of this " human subject, tend to, exhibit in book appeared, Mr. Wood has pub- " a sufficiently marked manner what Ushed another memoir in the 4 Phil. " may be considered as proofs and Transactions,* 1870, p. 83, on the " examples of the Darwinian prin- varieties of the muscles of the human " ciple of reversion, or law of in- neck, shoulder, and chest. He here " heritance, in this department of shews how extremely variable these " anatomical science." muscles are. ind how often and how 44 The Descent of Man. Part I part Various monstrosities, as I. Geoffroy repeatedly insists, arc thus intimately connected. Homologous structures are par- ticularly liable to change together, as we see on the opposite sides of the body, and in the upper and lower extremities. Meckel long ago remarked, that when the muscles of the arm depart from their proper type, they almost always imitate those of the leg ; and so, conversely, with the muscles of the legs. The organs of sight and hearing, the teeth and hair, the colour of the ckin and of the hair, colour and constitution, are more or less cor- related.55 Professor Schaaffhausen first drew attention to the relation apparently existing between a muscular frame and the strongly-pronounced supra-orbital ridges, which are so characteristic of the lower races of man. Besides the variations which can be grouped with more or less probability under the foregoing heads, there is a large class of variations which may be provisionally called spontaneous, for to our ignorance they appear to arise without any exciting cause. It can, however, be shewn that such variations, whether consisting of slight individual differences, or of strongly-marked and abrupt deviations of structure, depend much more on the constitution of the organism than on the nature of the condi- tions to which it has been subjected.56 Bate of Increase, — Civilised populations have been known under favourable conditions, as in the United States, to double their numbers in twenty-five years ; and, according to a calcula- tion by Euler, this might occur in a little over twelve years.*7 At the former rate, the present population of the United States (thirty millions), would in 657 years cover the whole terraqueous globe so thickly, that four men would have to stand on each square yard of surface. The primary or fundamental check to the continued increase of man is the difficulty of gaining subsistence, and of living in comfort. We may infer that this is the case from what we see, for instance, in the United States, where subsistence is easy, and there is plenty of room. If such means were suddenly doubled in Great Britain, our number would be quickly doubled. With civilised nations this primary check acts chiefly by restraining marriages. The greater death-rate of infants in the poorest classes is also very important; as well as 15 The authorities for these seve- my 'Variation of Animals and Plants ra) statements are given in my under Domestication.* * Variation of Animals under Do- 57 See the ever memorable ' Essay mesticaticn,' vol. ii. pp. 320-335. on the Principle of Population/ by *■ This whole subject has been the R«v. T. Malthus, vol. i. 1826 jk discussed in chap. siijL roj. ij. of 6, 517. CiiAi\ II. Manner of Development. 45 the greater mortality, from various diseases, of "the inhabitants of crowded and miserable houses, at all ages. The effects of severe epidemics and wars are soon counterbalanced, and more than counterbalanced, in nations placed under favourable conditions. Emigration also comes in aid as a temporary check, but, with the extremely poor classes, not to any great extent. There is reason to suspect, as Malthus has remarked, that the reproductive power is actually less in barbarous, than in civilised races. We know nothing positively on this head, for with savages no census has been taken; but from the concurrent testimony of missionaries, and of others who have long resided with such people, it appears that their families are usually small, and large ones rare. This may be partly accounted for, as it is believed, by the women suckling their infants during a long time ; but it is highly probable that savages, who often suffer much hardship, and who do not obtain so much nutritious food as civilised men, would be actually less prolific. I have shewn in a former work,58 that all our domesticated quadrupeds and birds, and all our cultivated plants, are more fertile than the corresponding species in a state of nature. It is no valid objection to this conclusion that animals suddenly supplied with an excess of food, or when grown very fat ; and that most plants on sudden removal from very poor to very rich soil, are rendered more or less sterile. We might, therefore, expect that civilised men, who in one sense are highly domesticated, would be more prolific than wild men. It is also probable that the increased fertility of civilised nations would become, as with our domestic animals, an inherited character : it is at least known that with mankind a tendency to produce twins runs in families.69 Notwithstanding that savages appear to be less prolific than civilised people, they would no doubt rapidly increase if their numbers were not by some means rigidly kept down. The San- tali, or hill-tribes of India, have recently afforded a good illustra- tion of this fact ; for, as shewn by Mr. Hunter,60 they have increased at an extraordinary rate since vaccination has been introduced, other pestilences mitigated, and war sternly repressed. This increase, however, would not have been possible had not these rude people spread into the adjoining districts, and worked for hire. Savages almost always marry ; yet there is some prudential restraint, for they do not commonly marry at the 58 'Variation of Animals and Foreign Medico-Chirurg. Review,' Plants under Domestication/ vol. ii. July, 1863, p. 170. pp. 111-113, 163. 6° 'The Annals of Rural Bengal, * Mr. Sedgwick, 'British and by W. W. Hunter, 186 H p. 259. 46 The Descent of Man. Pah? L earliest possible age. The young men are often required to shew that they can support a wife ; and they generally have first to earn the price with which to purchase her from her parents. With savages the difficulty of obtaining subsistence occasionally limits their number in a much more direct manner than with civilised people, for all tribes periodically suffer from severe famines. At such times savages are forced to devour much bad food, and their health can hardly fail to be injured. Many accounts have been published of their protruding stomachs and emaciated limbs after and during famines. They are then, also, compelled to wander much, and, as I was assured in Australia, their infants perish in large numbers. As famines are period- ical, depending chiefly on extreme seasons, all tribes must fluctuate in number. They cannot steadily and regularly increase, as there is no artificial increase in the supply of food. Savages, when hard pressed, encroach on each other's territories, and war is the result ; but they are indeed almost always at war with their neighbours. They are liable to' many accidents on land and water in their search for food ; and in some countries they suffer much from the larger beasts of prey. Even in India, districts have been depopulated by the ravages o: tigers. Malthus has discussed these several checks, but he does not lay stress enough on what is probably the most important of all, namely infanticide, especially of female infants, and the habit of procuring abortion. These practices now prevail in many quarters of the world ; and infanticide seems formerly to have prevailed, as Mr. M'Lennan61 has shewn, on a still more extensive scale. These practices appear to have originated in savages re- cognising the difficulty, or rather the impossibility of supporting all the infants that are born. Licentiousness may also be added to the foregoing checks; but this does not follow from failing means of subsistence; though there is reason to believe that in some cases (as in Japan) it has been intentionally encouraged as a means of keeping down the population. If we look back to an extremely remote epoch, before man had arrived at the dignity of manhood, he would have been guided more by instinct and less by reason than are the lowest savages at the present time. Our early semi-human progenitors would not have practised infanticide or polyandry; for the instincts of the lower animals are never so perverted ffl as to lead them re- CJ * Primitive Marriage,' 1865. ments as follows on this passage :— "A writer in the 'Spectator' "Mr. Darwin finds himself compelled (Jlarcn liitn, 1871, p. 320) com- " to reintroduce a new doctrine of the Cbap. ii. .Marnier of Development 47 gularly to destroy their own offspring, or to be quite devoid of jealousy. There would have been no prudential restraint from marriage, and the sexes would have freely united at an early age. Hence the progenitors of man would have tended to increase rapidly ; but checks of some kind, either periodical or constant, must have kept down their numbers, even more severely than with existing savages. What the precise nature of these, checks were, we cannot say, any more than with most other animals. We know that horses and cattle, which are not extremely prolific animals, when first turned loose in South America, increased at an enormous rate. The elephant, the slowest breeder of all known animals, would in a few thousand years stock the whole world. The increase of every species of monkey must be checked by some means; but not, as Brehm remarks, by the attacks of beasts of prey. No one will assume that the actual power of reproduction in the wild horses and cattle of Americaj was at first in any sensible degree increased ; or that, as each district became fully stocked, this same power was diminished. No doubt in this case, and in all others, many checks concur, and different checks under different circumstances ; periodical dearths, depending on unfavourable seasons, being probably the most important of all. So it will have been with the early pro- genitors of man. Natural Selection, — We have now seen that man is variable in body and mind ; and that the variations are induced, either directly or indirectly, by the same general causes, and obe$ 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,63 to the most diversified con- ditions. The inhabitants of Tierra del Fuego, the Cape of Good Hope, and Tasmania in the one hemisphere, and of the Arctic regions in the other, must have passed through many climates, " fall of man. He shews that the '* by the many foui customs, es- " instincts of the higher animals " pecially as to marriage, of savage " are far nobler than the habits of " tribes. What does the Jewish •*• savage races of men, and he finds • " tradition of the moral degeuera- " himself, therefore, compelled to " tion of man through his snatching " re-introduce, — in a form of the " at a knowledge forbidden him " substantial orthodoxy of which he " by his highest instinct assert " appears to be quite unconscious, — " beyond this?" ** and to introduce as a scientific 6S See some good remarks to this " hypothesis the doctrine that man's effect by W. Stanley Jevons, "A " gain of knowledge was the cause of " Deduction from Darwin's Theory/ ** a temporary but long-enduring * Nature,* 1869, p. 231. "• racial deterioration, n& indicated 4§ The Descent of Man. Pas? L and changed their habits many times, before they reached their present homes.64 The early progenitors of man must also havo 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 I 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,65 to incessant variability. If then the progenitors of man inhabit- ing any district, especially one undergoing some change in its conditions, were divided into two equal bodies, the one half which included all the individuals best adapted by their powers of movement for gaining subsistence, or for defending themselves, I would on an average survive in greater numbers, and procreate 1 more offspring than the other and less well endowed half. Man in the rudest state in which he now exists is the most dominant animal that has ever appeared on this earth. He has spread more widely that any other highly organised form : and all others have yielded before him. He manifestly owes this immense superiority to his intellectual faculties, to his social habits, which lead him to aid and defend his fellows, and to his corporeal structure. * The supreme importance of these characters has been proved by the final arbitrament of the battle for life. Through his powers of intellect, articulate language has been evolved; and on this his wonderful advancement has mainly depended. As Mr. Chauncey Wright remarks :66 " a psychological " analysis of the faculty of language shews, that even the smallest *' proficiency in it might require more brain power than the " greatest proficiency in any other direction." He has invented and is able to use various weapons, tools, traps, &c, with which he defends himself, kills or catches prey, and otherwise obtains food. He has made rafts or canoes for fishing or crossing over to neighbouring fertile islands. He has discovered the art of 64 Latham, * Man and his Migra- " classed in any of the above tions,' 1851, p. 135. " groups." These muscles differ 65 Messrs. Murie and Mivart in even on the opposite sides of the their 'Anatomy of the Lemuroidea' same individual. ('Transact. Zoolog. Soc* vol. vii. 66 Limits of Natural Selection, 1869, pp. 96-98) s&y, "some muscles * North American Be new/ Oct. ** are so irregular in their distriba- 1870, p. 295. ** tics that the-"- cannot be weH Chap. IT. Manner of Development 49 making fire, by which hard and stringy roots can bo rendered digestible, and poisonous roots or herbs innocuous. This dis- covery of fire, probably the greatest ever made by man, excepting language, dates from before the dawn of, history. These several inventions, by which man in the rudest state has become so pre- eminent, are the direct results of the development of his powers of observation, memory, curiosity, imagination, and reason. I cannot, therefore, understand how it is that Mr. Wallace67 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 man are of paramount importance to him, we must not underrate the importanae of his bodily structure, to which subject the remain- der of this chapter will be devoted ; the development of the in- tellectual and social or moral faculties being discussed in a later chapter. Even to hammer with precision is no easy matter, as every one who has tried to learn carpentry will admit. To throw a stone with as true an aim as a Fuegian in defending himself, or in killing birds, requires the most consummate perfection in the correlated action of the muscles of the hand, arm, and shoulder, and, further, a fine sense of touch. In throwing a stone or spear, and in many other actions, a man mast stand firmly on his feet ; and this again demands the perfect co-adaptation of numerous muscles. To chip a flint into the rudest tool, or to form a oarbed spear or hook from a bone, demands the use of a perfect hand; for, as a most capable judge, Mr. Schoolcraft,68 remarks, the shaping fragments of stone into knives, lances, or arrow-heads, 67 'Quarterly Review/ April here resist quoting a most just 1869, p. 392. This subject is more remark by Sir J, Lubbock (4 Pre- fuliy discussed in Mr. Wallace's historic Times,' 1865, p. 479) in ' Contributions to the Theory of reference to this paper, namely, that Natural Selection/ 1870, in which Mi. Wallace, "with characteristic all the essays referred to in this " unselfishness, ascribes it (i. e. the work are republished. The ' Essay " idea of natural selection) unre- on Man ' has been ably criticised by " servedly to Mr. Darwin, altnongh, Prof. Claparede, one of the most «* as is well known, he struck out distinguished zoologists in Europe, *' the idea independently, and pub- in an article published in the " lished it, though not with the ' Bibliotheque Universelle/ June " same elaboration, at the same 1870. The remark quoted in my "time." text will surprise every one who 8t Quoted by Mr. Lawson Tait in has read Mr. Wallace's celebrated his * Law of Natural Selection/ — paper on ' The Origin of Human 4 Dublin Quarterly Journal of Medi- Races deduced from the Theory of cal Science/ Feb. 1869. Dr. Keller Natural Selection/ originally pub- is likewise quoted to the same hshed in the * Anthropological Re- effect, view/ May 1864, p. clviii. I cannot |o Vke Descent of Man. Pabt I shews " extraordinary ability and long practice/' This is to a great extent proved by the fact that primeval men practised a division of labour; each man did not manufacture his own flint tools or rude pottery, but certain individuals appear to have devoted themselves to such work, no doubt receiving in exchange the produce of the chase. Archaeologists are convinced that an enormous interval of time elapsed before our ancestors thought of grinding chipped flints into smooth tools. One can hardly doubt, that a man-like animal who possessed a hand and arm sufficiently perfect to throw a stone with precision, or to form a flint into a rude tool, could, with sufficient practice, as far as mechanical skill alone is concerned, make almost anything which a civilised man can make. The structure of the hand in this respect may be compared with that of the vocal organs, which in the apes are used for uttering various signal-cries, or, as in one genus, musical cadences; but in man the closely similar vocal organs have become adapted through the inherited effects of use for the utterance of articulate language. / Turning now to the nearest allies of men, and therefore to its best representatives of our early progenitors, we find that the hands of the Quadrumana are constructed on the same general pattern as our own, but are far less perfectly adapted for diver- ; sified uses. Their hands do not serve for locomotion so well as the feet of a dog ; as may be seen in such monkeys as the chimpanzee and orang, which walk on the outer margins of the palms, or on the knuckles.69 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, in the same manner as we do. They can thus also lift rather large objects, such as the neck of a bottle, to their mouths. Baboons turn over stones, and scratch up roots with their hands. They seize nuts, insects, or other small objects with the thumb in opposition to the fingers, and no doubt they thus extract eggs and the young from the nests of birds. American monkeys beat the wild oranges on the branches until the rind is cracked, and then tear it off with the fingers of the two hands. In a wild state they break open hard fruits with stones. Other monkeys open mussel-shells with the two thumbs. With their fingers they pull out thorns and burs, and hunt for each other's parasites. They roll down stones, or throw them at their enemies : nevertheless, they are clumsy in these various actions, and, as I have myself seen, are quite unable to throw a stone with precision. 69 Ov, en, < Anatomy of Vertebrates/ vol. iii. p. 71, Chap. II. Manner of Development. 51 It seems to me far from true that because " objects are grasped " clumsily " by monkeys, " a much less specialised organ of " prehension " would have served them 7P equally well with their present hands. On the contrary, I see no reason to doubt that more perfectly constructed hands would have been an advantage to them, provided that they were not thus rendered less fitted for climbing trees. We may suspect that a hand as perfect as that of man would have been disadvantageous for climbing ; for the most arboreal monkeys in the world, namely, Ateles in America, Colobus in Africa, and Hylobates in Asia, are either thumbless, or their toes partially cohere, so that their limbs are converted into mere grasping hooks.71 As soon as some ancient member in the great series of the Primates came to be less arboreal, owing to a change in its manner of procuring subsistence, or to some change in the surrounding conditions, its habitual manner of progression would have been modified : and thus it would have been rendered more strictly quadrupedal or bipedal. Baboons frequent hilly and rocky districts, and only from necessity climb high trees ; 7a and they have acquired almost the gait of a dog. Man alone has become a biped ; and we can, I think, partly see how he has come to assume his erect attitude, which forms one of his most conspicuous characters. Man could not have attained his present dominant position in the world without the use of his hands, which are so admirably adapted to act in obedience to his will. Sir C. Bell 73 insists that " the hand supplies all instruments, •' and by its correspondence with the intellect gives him univer- " sal dominion." But the hands and arms could hardly have become perfect enough to have manufactured weapons, or to have hurled stones and 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 before remarked, so long as they were especially fitted for climbing trees. Such rough treatment would also have blunted the sense of touch, on which their delicate use largely depends. From these causes alone it would have been an advantage to man to become a biped; but for i0 * Quarterly Review/ April but whethei a better climber than 1869, p. 392. the species of the allied genera, I do 71 In Hylobates syndactylus, as not know. It deserves notice that *he name expresses, two of the toes the feet of the sloths, the most regularly cohere ; and this, as Mr. arboreal animals in the world, are Blyth informs me, is occasionally wonderfully hook-like, the case with the toes of H. agilis, n Brehm, ' Thierleben/ B. i. s. lar, and leuciscus. Colobus is strictly 80. arboreal and extraordinarily active n "The Hand," &c. *Bridge- (Brehm, « Thierleben,' B. i. s. 50), water Treatise/ 1833, p. 38. E 2 52 The Descent of Man. Paet l many actions it is indispensable that the arms and whole upper part of the body should be free ; and he must for this end stand firmly on his feet. To gain this great advantage, the feet have been rendered flat ; and the great toe has been peculiarly modi- fied, though this has entailed the almost complete loss of its power of prehension. It accords with the principle of the division of physiological labour, prevailing throughout the animal kingdom, that as the hands became perfected for pre- hension, the feet should have become perfected for support and locomotion. With some savages, however, the foot has not altogether lost its prehensile power, as shewn by their manner of climbing trees, and of using them in other ways.74 If it be an advantage to man to stand firmly on his feet and to have his hands and arms free, of which, from his pre-eminent success in the battle of life, there can be no doubt, then I can see no reason why it should not have been advantageous to the progenitors of man to have become more and more erect or bipedal. They would thus have been better able to defend themselves with stones or clubs, to attack their prey, or other- wise to obtain food. The best built individuals would in the long run have succeeded best, and have survived in larger numbers. If the gorilla and a few allied forms had 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 the anthropomorphous apes are now actually in an intermediate condition ; and no one doubts that they are o the whole well adapted for their conditions of life. Thus the gorilla runs with a sidelong shambling gait, but more commonly progresses by resting on its bent hands. The long-armed apes occasionally use their arms like crutches, swinging their bodies forward between them, and some kinds of Hylobates, without having been taught, can walk or run upright with tolerable quickness ; yet they move awkwardly, and much less securely than man. We see, in short, in existing monkeys a manner of progression intermediate between that of a quadruped and a u Hackel lias an excellent dis- foot as a prehensile organ by man ; cussion on the steps by which man and has also written on the mannei became a biped : * Natiirliche Schbp- of progression of the higher apes, to fungsgeschichte/ 1868, s. 507. Dr. which I allude in the following Biichner (* Conferences sur la Theorie paragraph : see also Owen (' Anatomy Darwinienne,' 1869, p. 135) has of Vertebrates/ vol. iii, p. 71) ou given good cases of the use of the this latter subject. Chap. II. Manner of Development 53 biped ; but, as an unprejudiced judge 75 insists, the anthropomor- phous apes approach in structure more nearly to the bipedal than to the quadrupedal type. As the progenitors of man became more and more erect, with their hands and arms more and more modified for prehension and other purposes, with their feet and legs at the same time transformed for firm support and progression, endless other changes of structure would have become necessary. The pelvis would have to be broadened, the spine peculiarly curved, and the head fixed in an altered position, all which changes have been attained by man. Prof. Schaaff hausen 76 maintains that "the " powerful mastoid processes of the human skull are the result of " his erect position ;" and these processes are absent in the orang, chimpanzee, &c, and are smaller in the gorilla than in man. Various other structures, which appear connected with man's erect position, might here have been added. It is very difficult to decide how far these correlated modifications are the result of natural selection, and how far of the inherited effects of the increased use of certain parts, or of the action of one part on another. No doubt these means of change often co-operate : thus when certain muscles, and the crests of bone to which they are attached, become enlarged by habitual use, this shews that certain actions are habitually performed and must be serviceable. Hence the individuals which performed them best, would tend to survive in greater numbers. ^ The free use of the arms and hands, partly the cause and \ partly the result of man's erect position, appears to have led in an I indirect manner to other modifications of structure. The earlv^/ male forefathers of man were, as previously stated, probably l furnished with great canine teeth; but as they gradually acquired the habit of using stones, clubs, or other weapons, for fighting with their enemies or rivals, they would use their jaws and teeth less and less. In this case, the jaws, together with the teeth, would become reduced in size, as we may feel almost sure from innumerable analogous cases. In a future chapter we shall meet with a closely parallel case, in the reduction or com- plete disappearance of the canine teeth in male ruminants, apparently in relation with the development of their horns ; and in horses, in relation to their habit of fighting with their incisor teeth and hoofs. 74 Prof. Broca, La Constitution the Skull/ translated in * Anthro- des Vertebres caudales, 'La Revue pological Review/ Oct. 1868, p. d'Anthropologie/ 1871, p. 26, 428. Owen (' Anatomy of Verte- (separate cop}'). brates/ vol. ii. 1866, p. 551) on the Tti * On tha Primitive Form of mastoid processes in the higher apea. 54 T lie Descent of Man. Part I, In the adult male anthropomorphous apes, as Eiitimeyer,77 and others, have insisted, it is the effect on the skull of the great development of the jaw-muscles that causes it to differ so greatly in many respects from that of man, and has given to these animals " a truly frightful physiognomy." Therefore, as the jaws and teeth in man's progenitors gradually became reduced in size, the adult skull would have come to resemble more and more that of existing man. As we shall hereafter see, a great reduction of the canine teeth in the males would almost certainly affect the teeth of the females through inheritance. As the various mental faculties gradually developed themselves the brain would almost certainly become larger. No one, I presume, doubts that the large proportion which the size of man's brain bears to his body, compared to the same proportion in the gorilla or orang, is closely connected with his higher mental powers. We meet with closely analogous facts with insects, for in ants the cerebral ganglia are of extraordinary dimensions, and in all the Hymenoptera these ganglia are many times larger than in the less intelligent orders, such as beetles.78 On the other hand, no one supposes that the intellect of any two animals or of any two men can be accurately gauged by the cubic contents of their skulls. It is certain that there may be extraordinary mental activity with an extremely small absolute mass of nervous matter: thus the wonderfully diversified instincts, mental powers, and affections of ants are notorious^ yet their cerebral ganglia are not so large as the quarter of a small pin's head. Under this* point of view, the brain of an ant is one of the most marvellous atoms of matter in the world, perhaps more so than the brain of a man. The belief that there exists in man some close relation between the size of the brain and the development of the intellectual faculties is supported by the comparison of the skulls of savage and civilised races, of ancient and modern people, and by the analogy of the whole vertebrate series. Dr. J. Barnard Davis has proved,79 by many careful measurements, that the mean internal capacity of the skull in Europeans is 92*3 cubic inches; in Americans 87*5 ; in Asiatics 87*1 ; and in Australians only 81 '9 cubic inches. Professor Broca80 found that the nineteenth century 77 'Die Grenzen der Thierwelt, vomitoria* 1870, p. 14. My son, eine Betrachtung zu Darwin's Lehre/ Mr. F. Darwin, dissected for me the 1868, s. 51. cerebral ganglia of the Formica 78 Dujardin, * Annales des Sc. rufa. Nat,* 3rd series Zoolog. torn. xiv. 79 < Philosophical Transactions, 1850, p. 203. See also Mr. Lowne, 1869, p. 513. Anatomy and Phys. of the Musca 80 * Les Selections, M, P. Bra.-*, Chap. II. Manner of Development. 55 skulls from graves in Paris were larger than those from varilta of the twelfth century, in the proportion of 1484 to 1426 ; an J. that the increased size, as ascertained by measurements, was exclusively in the frontal part of the skull — the seat of the intellectual faculties. Prichard is persuaded that the present inhabitants of Britain have " much more capacious brain-cases " than the ancient inhabitants. Nevertheless, it must be admitted that some skulls of very high antiquity, such as the famous one of Neanderthal, are well developed and capacious.81 With respect to the lower animals, M. E. Lartet,82 by comparing the crania of tertiary and recent mammals belonging to the same groups, has come to the remarkable conclusion that the brain is generally larger and the convolutions are more complex in the more recent forms. On the other hand, I have shewn83 that the brains of domestic rabbits are considerably reduced in bulk, in comparison with those of the wild rabbit or hare ; and this may be attributed to their having been closely confined during many generations, so that they have exerted their intellect, instincts, senses and voluntary movements but little. The gradually increasing weight of the brain and skull inj man must have influenced the development of the supporting \ spinal column, more especially whilst 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 j which infants sleep. Habitual spasms of the muscles, and a ' cicatrix from a severe burn, have permanently modified the facial bones. In young persons whose heads have become fixed either sideways or backwards, owing to disease, one of the two eyes has changed its position, and the shape of the skull has been altered Revue d'Anthropologies,' 1873 ; the other hand, with savages, the ave- see also, as quoted in C. Vogt's rage includes only the more capable ' Lectures on Man/ Eng. transiat. individuals, who have been able to 1864, pp. 88,90. Prichard, 'Phys. survive under extremely hard con- Hist. of Mankind,' vol. i. 1838, p. ditions of life. Broca thus explains 305. the otherwise inexplicable fact, that 81 In the interesting article just the mean capacity of the skull of referred to, Prof. Broca has well the ancient Troglodytes of Lozere is remarked, that in civilised nation*, greater than that of modern French- the average capacity of the skull men. must be lowered by the preserva- 82 ' Comptes-rendus des Sciences,' tion of a considerable number of &c. June 1, 1868. individuals, weak in mind and body, 8* ' The Variation of Animals and who would have been promptly Plants under P^mesticaticn,' voL i, tiixuinatcd in the savage state. On pp. 124- 129. $6 The Descent of Man. Paat I apparently by the pressure of the brain in a new direction.84 I have shewn that with long-eared rabbits even m trifling a cause as the lopping forward of one ear drags forward almost ever$ t>one of the skull on that side ; so that the bones on the opposite side no longer strictly correspond. Lastly, if any animal were to increase or diminish much in general size, without any change in its mental powers, or if the mental powers were to be much increased or diminished, without any great change in the size of the body, the shape of the skull would almost certainly be V^jiltered. I infer this from my observations on domestic rabbits, some kinds of which have become very much larger than the wild animal, whilst others have retained nearly the same size, but in both cases the brain has been much reduced relatively to the size of the body. Now I was at first much surprised on finding that in all these rabbits the skull had become elongated or dolichocephalic; for instance, of two skulls of nearly equal breadth, the one from a wild rabbit and the other from a large domestic kind, the former was 315 and the latter 4*3 inches in length.85 One of the most marked distinctions in different races of men is that the skull in some is elongated, and in others rounded; and here the explanation suggested by the case of the rabbits may hold good; for Welcker finds that short "men incline more " to brachycephaly, and tall men to dolichocephaly ;"86 and tall men may be compared with the larger and longer-bodied rabbits, all of which have elongated skulls, or are dolicho- cephalic. From these several facts we can understand, to a certain extent, the means by which the great size and more or less rounded form of the skull have been acquired by man ; and these are characters eminently distinctive of him in comparison with the lower animals. Another most conspicuous difference between man and the lower animals is the nakedness of his skin. Whales and porpoises (Cetacea), dugongs (Sirenia) and the hippopotamus are naked; and this may be advantageous to them for gliding 84 Schaaffhausen gives from Blu- maker, where the head is habitually menbach and Busch, the cases of the held forward, the forehead become* spasms and cicatrix, in 'Anthro- more rounded and prominent, polog. Review/ Oct. 1868, p. 420. " 'Variation of Animals/ &c, Dr. Jarrold ('Anthropologic* 1808, vol. i. p. 117, on the elongation of pp. 115, 116) adduces from Camper the skull; p. 119, on the effect of and from his own observations, cases the lopping of one ear. of the modification of the skull from *6 Quoted by Scha&fThausen, in the head being fixed in an unnatural ' Anthropolog. Review/ Oct. 1868, position. He believes that in cer- p. 419. tain trades, such &s that of a shoe- Chap. II. Manner of Development 57 through the water; nor would it be injurious to them from tho loss of warmth, as the species, which inhabit the colder regions, are protected by a thick layer of blubber, serving the same purpose as the fur of seals and otters. Elephants and rhino- ceroses are almost hairless ; and as certain extinct species, which formerly lived under an Arctic climate, were covered with long wool or hair, it would almost appear as if the existing species of both genera had lost their hairy covering from exposure to heat. This appears the more probable, as the elephants in India which live on elevated and cool districts are more hairy 87 than those on the lowlands. May we then infer that man became divested of hair from having aboriginally inhabited some tropical land ? That the hair is chiefly retained in the male sex on the chest and face, and in both sexes at the junction of all four limbs with the trunk, favours this inference — on the assumption that the hair was lost before man became erect ; for the parts which now retain most hair would then have been most protected from the heat of the sun. The crown of the head, however, offers a curious exception, for at all times it must have been one of the most exposed parts, yet it is thickly clothed with hair. The fact, however, that the other members of the order of Primates, to which man belongs, although inhabiting various hot regions, are well clothed with hair, generally thickest on the upper surface,88 is opposed to the supposition that man became naked through the action of the sun. Mr. Belt believes 89 that within the tropics it is an advantage to man to be destitute of hair, as he is thus enabled to free himself of the multitude of ticks (acari) and other parasites, with which he is often infested, and which sometimes cause ulceration. But whether this evil is of sufficient magnitude to have led to the denudation of his body thrcugh natural selection, may be doubted, since none of the many quadrupeds inhabiting the tropics have, as far as I know, acquired any specialised means of relief. The view which seems to me the most probable is that man, or rather primarily woman, 87 Owen, * Anatomy of Verte- ever, states that in the Gorilla the orates/ vol. iii. p. 619. hair is thinner on the back, where 88 Isidore Geoffroy St.-Hilaire re- it is partly rubbed off, than on the marks (* Hist. Nat. Ge'ne'rale,' torn, lower surface. li. 1859, pp. 215-217) on the head of 8* The * Naturalist in Nicaragua,' man being covered with long hair ; 1874, p. 209. As some confirma- also on the upper surfaces of mon- tion of Mr. Belt's view, I may quote keys and of other mammals being the following passage from Sir W. more thickly clothed than the lower Denison (' Varieties of Vice-Regal surfaces. This has likewise been Life/ vol. i. 1870, p. 440): "It is said observed by various authors. Prof. *' to be a practice with the Aus- P. Gervais (' Hist. Nat. des Mam- " tralians, when the vermin get miteres,' torn. \ 1854, p. 28), how- " troublesome, to singe theixiselvw*.*1 $8 The Descent of Mat* Pakt I. became divested of hair for ornamental purposes, as we shall sp*, under Sexual Selection ; and, according to this belief, it is not surprising that man should differ so greatly in hairiness from all other Primates, for characters, gained through sexual selection, often differ to an extraordinary degree in closely-related forms. According to a popular impression, the absence of a tail is eminently distinctive of man; but as those apes which come nearest to him are destitute of this organ, its disappearance does not relate exclusively to man. The tail often differs remarkably in length within the same genus : thus in some species of Hacacus it is longer than the whole body, and is formed of twenty-four vertebras; in others it consists of a scarcely visible stump, containing only three or four vertebra. In some kinds of baboons there are twenty-five, whilst in the mandrill there are ten very small stunted caudal vertebrae, or, according to Cuvier,5* sometimes only five. The tail, whether it be long or short, almost always tapers towards the end ; and this, I presume, results from the atrophy of the terminal muscles, together with their arteries and nerves, through disuse, leading to the atrophy of the terminal bones. But no explanation can at present be given of the great diversity which often occurs in its length. Here, however, we are more specially concerned with the complete external dis- appearance of the tail. Professor Broca has recently shewn91 that the tail in all quadrupeds consists of two portions, generally separated abruptly from each other ; the basal portion consists of vertebrae, more or less perfectly channelled and furnished with apophyses like ordinary vertebrae ; whereas those of the terminal portion are not channelled, are almost smooth, and scarcely resemble true vertebrae. A tail, though not externally visible, is really present in man and the anthropomorphous apes, and is constructed on exactly the same pattern in both. In the terminal portion the vertebrae, constituting the os cocct/x, are quite rudimentary, being much reduced in size and number. In the basal portion, the vertebrae are likewise few, are united firmly together, and are arrested in development ; but they have been rendered much broader and flatter than the corresponding vertebrae in the tails of other animals : they constitute what Broca calls the accessory sacral vertebrae. These are of functional importance by supporting certain internal parts and in other ways ; and their modification is directly connected with the erect 90 Mi , St. George Mivart, « Proc. Geoffroy, < Hist. Kat. Gen/ torn. ii. Zoolog, Soc.' 1865, pp. 562, 583. p. 244. Dr. J. E.. Gray, l Cat. Brit. Mus. : 9l < Revue d' Anthropologic' 1872; Skeletons.' Owen, * Anatomy of } La Constitution des Vertebres cata- Vei tebrates,' vol h. p. 517. Isidore dales.* Chap.IL Manner of Development 59 or semi-erect attitude of man and the anthropomorphous apes. This conclusion is the more trustworthy, as Broca formerly held a different view, which he has now abandoned. The modifica- tion, therefore, of the basal caudal vertebrae in man and the higher apes may have been effected, directly or indirectly, through natural selection. But what are we to say about the rudimentary and variable vertebra of the terminal portion of the tail, forming the os coccyx ? A notion which has often been, and will no doubt again be ridiculed, namely, that friction has had something to do with the disappearance of the external portion of the tail, is not so ridiculous as it at first appears. Dr. Anderson92 states that the extremely short tail of Macacus brunneus is formed of eleven vertebrae, including the imbedded basal ones. The extremity is tendinous and contains no vertebras; this is suc- ceeded by five rudimentary ones, so minute that together they are only one line and a half in length, and these are permanently bent to one side in the shape of a hook. The free part of the tail, only a little above an inch in length, includes only four more small vertebrae. This short tail is carried erect; but about a quarter of its total length is doubled on to itself to the left ; and this terminal part, which includes the hook-like portion, serves " to fill up the interspace between the upper divergent portion " of the callosities ;" so that the animal sits on it, and thus renders it rough and callous. Dr. Anderson thus sums up his observa- tions : " These facts seem to me to have only one explanation ; " this tail, from its short size, is in the monkey's way when it " sits down, and frequently becomes placed under the animal *' while it is in this attitude ; and from the circumstance that it " does not extend beyond the extremity of the ischial tuberosities " it seems as if the tail originally had been bent round, by the " will of the animal, into the interspace between the callosities, to " escape being pressed between them and the ground, and that "in time the curvature became permanent, fitting in of itself " when the organ happens to be sat upon." Under these circum- stances it is not surprising that the surface of the tail should have been roughened and rendered callous * and Dr. Murie,93 who carefully observed this species in the Zoological Gardens, as well as three other closely allied forms with slightly longer tails, says that when the animal sits down, the tail " is necessarily thrust * to one side of the buttocks ; and whether long or short its root * is consequently liable to be rubbed or chafed." As we now e* 4 Proc. Zwnog. Soc.,' 1872, p. •» < Proc. Zwlog. Soc. \Wl% p 310. 786. 60 The Descent of Man. Tabu 1 have evidence that mutilations occasionally produce an inherited effect,94 it is not very improbable that in short-tailed monkeys, the projecting part of the tail, being functionally useless, should after many generations have become rudimentary and distorted, from being continually rubbed and chafed. We see the projecting part in this condition in the Macacus brunneus, and absolutely aborted in the M. ecaudatus and in several of the higher apes. Finally, then, as far as we can judge, the tail has disappeared in man and the anthropomorphous apes, owing to the terminal portion having been injured by friction during a long lapse of time ; the basal and embedded portion having been reduced and modified, so as to become suitable to the erect or semi-erect position. I have now endeavoured to shew that some of the most distinctive characters of man have in all probability been acquired, either directly, or more commonly indirectly, through natural selection. We should bear in mind that modifications in structure or constitution, which do not serve to adapt an organism to its habits of life, to the food which it consumes, or passively to the surrounding conditions, cannot have been thus acquired. We must not, however, be too confident in deciding what modifications are of service to each being: we should remember 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 new kinds of food. Nor must we forget the principle of correlation, by which, as Isidore Geoffroy has shewn in the case of man, many strange deviations of structure are tied together. Independently of correlation, a change in one part often leads, through the increased or decreased use of other parts, to other changes of a quite unexpected nature. It is also well to reflect on such facts, as the wonderful growth of galls on plants caused by the poison of an insect, and on the remarkable changes of colour in the plumage of parrots when fed on certain fishes, or inoculated with the poison of toads;95 for we can thus see that the fluids of the system, if altered for some special purpose, might induce other changes. We should especially bear in mind that modifications acquired 94 I allude to Dr. Brown-Seq card's inherited effects of mot-mots biting observations on the transmitted off the barbs of their own tai)- effect of an operation causing epi- feathers. See also on the general lepsy in guinea-pigs, and likewise subject * Variation of Animals and more recently on the analogous Plants under Domestication,' vol. effects of cutting the sympathetic ii., pp. 22-24. nerve in the neck. I shall hereafter 85 ' The Variation of Animals and have occasion to refer to Mr. Salvin;s Plants under Domestication,' vol. i> interestijig case of the apparently pp. 280, 282. Ohap. IL Manner of Development. & * and continually used during past ages for some useful purpose, would probably become firmly fixed, and might be long inherited. Thus a large yet undefined extension may safely be given to the direct and indirect results of natural selection ; but I now admit, after reading the essay by Nageli on plants, and the remarks by various authors with respect to animals, more especially those recently made by Professor Broca, that in the earlier editions of my * Origin of Species ' I perhaps attributed too much to the action of natural selection or the survival oJ the fittest. I have altered the fifth edition of the ' Origin ' so as to confine my remarks to adaptive changes of structure ; but I am convinced, from the light gained during even the last few years that very many structures which now appear to us useless, will hereafter be proved to be useful, and will therefore come within the range of natural selection. Nevertheless, I did not formerly consider sufficiently the existence of structures, which, as far as we can at present judge, are neither beneficial nor injurious and this I believe to be one of the greatest oversights as yet detected in my work. I may be permitted to say, as some excuse, that I had two distinct objects in view; firstly, to shew that species had not been separately created, and secondly, that natural selection had been the chief agent of change, though largely aided by the inherited effects of habit, and slightly by the direct action of the surrounding conditions. I was not, however, able to annul the influence of my former belief, then almost universal, that each species had been purposely created ; and this led to my tacit assumption that every detail of structure, excepting rudiments, was of some special, though unrecognised, service. Any one with this assumption in his mind would naturally extend too far the action of natural selection, either during past or present times. Some of those who admit the principle of evolution, but reject natural selec- tion, seem to forget, when criticising my book, that I had the above two objects in view ; hence if I have erred in giving to natural selection great power, which I am very far from admitting, or in having exaggerated its power, which is in itself probable, I have at least, as I hope, done good service in aiding to overthrow the dogma of separate creations. It is, as I can now see, probable that all organic beings, including man, possess peculiarities of structure, which neither are now, nor were formerly of any service to them, and which, therefore, are of no physiological importance. We know not what produces the numberless slight differences between tho individuals of each species, for reversion only carries the problem a few steps backwards; but each peculiarity must 6.2 TJie Descent of Man, Part I have had its efficient cause. If these causes, whatever they may be, were to act more uniformly and energetically during a lengthened period (and against this no reason can be assigned), the result would probably be not a mere slight individual difference, but a well-marked and constant modification, though one of no physiological importance. Changed structures, which are in no way beneficial, cannot be kept uniform through natural selection, though the injurious will be thus eliminated. Uni- formity of character would, however, naturally follow from the assumed uniformity of the exciting causes, and likewise from the free intercrossing of many individuals. During successive periods, the same organism might in this manner acquire successive modifications, which would be transmitted in a nearly uniform 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 spon- taneous variations, that they relate much more closely to the constitution of the varying organism, than to the nature of the conditions to which it has been subjected. Conclusion, — In this chapter we have seen that as man at the present day is liable, like every other animal, to multiform individual differences or slight variations, so no doubt were the early progenitors of man ; the variations being formerly induced by the same general causes, and governed by the same general jind complex laws as at present. As all animals tend to multiply • beyond their means of subsistence, so it must have been with the progenitors of man; and this would inevitably lead to a struggle for existence and to natural selection. The latter process would be greatly aided by the inherited effects of the increased use of parts, and these two processes would incessantly react on each other. It appears, also, as we shall hereafter see, that various unimportant characters have been acquired by man through sexual selection. An unexplained residuum of change must be left to the assumed uniform action of those unknown agencies, which occasionally induce strongly marked and abrupt deviations of structure in our domestic productions. Judging from the habits of savages and of the greater number of the Quadrumana, primeval men, and even their ape-like progenitors, probably lived in society. With strictly social animals, natural selection sometimes acts on the individual, through the preservation of variations which are beneficial to the community. A community which includes a large number of well-endowed individuals increases in number, and is victo- rious over ether less favoured ones; even although each separate / { Chap. II. Manner of Development. 63 membeij gains no advantage over the others of the same com- munity. Associated insects have thus acquired many remark- able structures, which are of little or no service to the individual, such as the pollen-collecting apparatus, or the sting of the worker^bee, or the great jaws of soldier-ants. 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 powers the case, as we shall see in the fifth chapter, is wholly different ; for these faculties have been chiefly, or even exclusively, gained for the benefit of the community, and the individuals thereof, have at the same time gained an advantage indirectly. It has often been objected to such views as the foregoing, that man is one of the most helpless and defenceless creatures in the world; and that during his early and less well-developed condition he would have been still more helpless. The Duke of Argyll, for instance, insists96 that "the human frame has " diverged from the structure of brutes, in the direction of •' greater physical helplessness and weakness. That is to say, it " is a divergence which of all others it is most impossible to " ascribe to mere natural selection." He adduces the naked and unprotected state of the body, the absence of great teeth or claws for defence, the small strength and speed of man, and his slight power of discovering food or of avoiding danger by smell. To these deficiencies there might be added one still more serious, namely, that he cannot climb quickly, and so escape- from enemies. The loss of hair would not have been a great injury to the inhabitants of a warm country. For we know that the unclothed Fuegians can exist under a wretched climate. When we compare the defenceless state of man with that of apes, we must remember that the great canine teeth with which the latter are provided, are possessed in their full development by the males alone, and are chiefly used by them for fighting with their rivals; yet the females, which are not thus provided, manage to survive. In regard to bodily size or strength, we do not know whether man is descended from some small species, 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 •• * Primeval Man,5 1869, p. 66 64 The Descent of Man. \ Va rt I and weaker, than his ancestors. We should, however, i bear in mind that an animal possessing great size, strength, and /ferocity, and which, like the gorilla, could defend itself from all Enemies, would not perhaps have become social; and this would most effectually have checked the acquirement of the higherS mental qualities, such as sympathy and the love of his fellows. Hence it might have been an immense advantage to man to have sprung from some comparatively weak creature. The small strength and speed of man, his want of natural weapons, &c, are more than counterbalanced, firstly, by his intellectual powers, through which he has formed for himself weapons, tools, &c, though still remaining in a barbarous state, and, secondly, by his social qualities which lead him to give and receive aid from his fellow-men. No country in the world abounds in a greater degree with dangerous beasts than Southern Africa ; no country presents more fearful physical hardships than the Arctic regions ; yet one of the puniest of races, that of the Bushmen, maintains itself in Southern Africa, as do the dwarfed Esquimaux in the Arctic regions. The ancestors 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 they had advanced in intellect, whilst gradually losing their brute-like powers, such as that of climbing trees, &c. Bmt these ancestors would not have been exposed to any special danger, even if far more helpless and defenceless than any existing savages, had they inhabited some warm continent or large island, such as Australia, New Guinea, or Borneo, which is now the home of the orang. And natural selection arising from the competition of tribe with tribe, in some such large area as one of these, together with the inherited effects of habit, would, under favourable conditions, have sufficed to raise man to his present high position in the organic scale. Ceai\ III. Mental Powers. 65 CHAPTER in. Comparison of jthe 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 — Reason — Progressive improvement — Tools and weapons used by animals — Abstraction, self-consciousness — Language — Sense of beauty — Belief in God, spiritual agencies, superstitions. We have seen in the last two chapters 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 hardly any abstract terms for common objects or for the affections,1 with that of the most highly , organised ape. The difference would, no doubt, still remain / immense, even if one of the higher apes had been improved or civilised as much as a dog has been in comparison with, its parent-form, the wolf or jackal. The Fuegians rank amongst the lowest barbarians; but I was continually struck with surprise how closely the three natives on board H.M.S. " Beagle," who had lived some years in England, and could talk a little . English, resembled us in disposition and in most of our mental ^ faculties. If no organic being excepting man had possessed any mental power, or if his powers had been of a wholly different nature, from those of the lower animals, then we should nevei have been able to convince ourselves that our high faculties had been gradually developed. Put it can be shewn that there is no fundamental difference of this kind. We must also admit \ that there is a much wider interval in mental power between one of the lowest fishes, as a lamprey or lahcelet, and one of the higher apes, than between an ape and man ; yet this interval is filled up by numberless gradations. Nor is the difference slight in moral disposition between a barbarian, such as the man described by the old navigator 1 See the evidence on those points, as given by Lubbock, » Prehistorio Times,' p. 354, &e 66 The Descent of Man. Part 1, Byron, who dashed his child on the rocks for dropping a basket of sea-urchins, and a Howard or Clarkson; and in intellect, between a savage who uses hardly any abstract terms, and a Newton or Shakspeare. Differences of this kind between the highest men of the highest races and the lowest savages, are connected by the finest gradations. Therefore it is possible that they might pass and be developed into each other. My object in this chapter is to shew that there is no funda- mental difference between man and the higher mammals in their mental faculties. Each division of the subject might have been extended into a separate essay, but must here be treated briefly. As no classification of the mental powers has been universally accepted, I shall arrange my remarks in the order most con- venient for my purpose ; and will select those facts which have struck me most, with the hope that they may produce some effect on the reader. With respect to animals very low in the scale, I shall give some additional facts under Sexual Selection, shewing that their mental powers are much higher than might have been expected. The variability of the faculties in the individuals of the same species is an important point for us, and some few illustrations will here be given. But it would be superfluous to enter into many details on this head, for I have found on frequent enquiry, that it is the unanimous opinion of all those who have long attended to animals of many kinds, including birds, that the individuals differ greatly in every mental characteristic. In what manner the mental powers were first developed in the lowest organisms, is as hopeless an enquiry as how life itself first originated. These are problems for the distant future, if they are e^er to be solved by man. As man possesses the same senses as the lower animals, his fundamental intuitions must be the same. Man has also some few instincts in common, as that of self-preservation, sexual love, the love of the mother for her new-born offspring, the desire possessed by the latter to suck, and so forth. But man, perhaps, has somewhat fewer instincts than those possessed by the animals which come next to him in the series. The orang in the Eastern islands, and the chimpanzee in Africa, build plat- forms on which they sleep; and, as both species follow the same habit, it might be argued that this was due to instinct, but we cannot feci sure that it is not the result of both animals having similar wants, and possessing similar powers of reasoning. These apes, as we may assume, avoid the many poisonous fruits of the tropics, and man has no such knowledge : but as our domestic animals, when taken to foreign lands, and when first Oh a p. III. Mental Powers. 6J turned out in the spring, often eat poisonous herbs, which they afterwards avoid, we cannot feel sure that the apes do not learn from their own experience or from that of their parents wha$ fruits to select. It is, however, certain, as we shall presently sea, that apes have an instinctive dread of serpents, and probably 01 other dangerous animals. ^ The fewness and the comparative simplicity of the instincts in the higher animals are remarkable in contrast with those of tho 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 shewn that no such inverse ratio really exists. Those insects which possess the most wondeiful instincts are certainly tho most intelligent. In the vertebrate series, the least intelligent members, namely fishes and amphibians, do not possess complex instincts; and amongst mammals the animal most remarkable for its instincts, namely the beaver, is highly intelligent, as will be admitted by every one who has read Mr. Morgan's excellent Work.3 Although the first dawnings of intelligence, according to Mr. Herbert Spencer/ have been developed through the multiplicar tion and co-ordination of reflex actions, and although many of the simpler instincts graduate into reflex actions, and can hardly be distinguished from them, as in the case of young animate sucking, yet the more complex instincts seem to have originated independently of intelligence. I am, however, very far from wishing to deny that instinctive actions may lose their fixed and untaught character, and be replaced by others performed by the aid of the free will. On the other hand, some intelligent actions, after being performed during several generations, become con- verted into instincts and are inherited, as when birds on oceanic islands learn to avoid man. These actions may then be said to be degraded in character, for they are no longer performed through reason or from experience. But the greater number of the more complex instincts appear to have been gained in a wholly different manner, through the natural selection of varia- tions of simpler instinctive actions. Such variations appear to arise from the same unknown causes acting on the cerebral organisation, which induce slight variations or individual dif- ferences in other parts of the body ; and these variations, owing a ' I/Instincfc chez les Insectes.* 3 ' The American Beaver and Lie * Revuf des Deux Mondes/ Feb. 1870, Works,' 1868. p. 6^0. 4 ' The Principles of Psychology, 2nd edit 1870, pp. 418-4-W. F 2 6$ The Descent of Man. Past I to our ignorance, are oftca said to arise spontaneously. We can, I think, come to no other conclusion with respect to the origin of the more complex instincts, when we reflect on the marvellous instincts of sterile worker-ants and bees, which leave no off- spring to inherit the effects of experience and of modified habits. Although, as we learn from the above-mentioned insects and the beaver, a high degree of intelligence is certainly compatible with complex instincts, and although actions, at first learnt voluntarily can soon through habit be performed with the quickness and certainty of a reflex action, yet it is not improbable that there is a certain amount of interference between the development of free intelligence and of instinct, — which latter implies some inherited modification of the brain. Little is known about the functions of the brain, but we can perceive that as the intellectual powers become highly developed, the various parts of the brain must be connected by very intricate channels of the freest intercommunication; and as a conse- quence, each separate part would perhaps tend to be less well fitted to answer to particular sensations or associations in a definite and inherited — that is instinctive— manner. There seems even to exist some relation between a low degree of intelligence and a strong tendency to the formation of fixed, though not inherited habits ; for as a sagacious physician remarked to me, persons who are slightly imbecile tend to act in everything by routine or habit ; and they are rendered much happier if this is en- couraged. I have thought this digression worth giving, because we may easily underrate the mental powers of the higher animals, and especially of man, when we compare their actions founded on the memory of past events, on foresight, reason, and imagination, with exactly similar actions instinctively performed by the lower animals ; in this latter case the capacity of performing such actions has been gained, step by step, through the variability of the mental organs and natural selection, without any conscious intelligence on the part of the animal during each successive generation. No doubt, as Mr. Wallace has argued,6 much of the intelligent work done by man is due to imitation and not to reason; but there is this great difference between his actions and many of those performed by the lower animals, namely, that man cannot, on his first trial, make, for instance, a stone hatchet or a canoe, through his power of imitation. He has to learn his work by practice ; a beaver, on the other hand, can make its dam or canal, and a bird its nest, as. well, or nearly as well, and *.* Contributions to the Theojy of Matural Selection,' 1870, j*. 212, Chap. III. Mental Powers, a spider its wonderful web, quite as well/ the first time it tries as when old and experienced. . To return to our immediate subject : tho lower animals, like man, manifestly feel pleasure and pain, happiness and misery. Happiness is never better exhibited than by young animals, sucb as puppies, kittens, lambs, &c, when playing together, like our own children. Even insects play together, as has been described by that excellent observer, P. Huber,7 who saw ants chasing and pretending to bite each other, like so many puppies. Tho 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. Ifc is, I think, impossible to read the account given by Sir E. Tennent, of the behaviour of the female elephants, used as decoys, without admitting that they intentionally practise deceit, and well know what they are about. Courage and timidity are extremely variable qualities in the individuals of the same species, as is plainly seen in our dogs. Some dogs and horses are ill-tempered, and easily turn sulky ; others are good-tempered ; and these qualities are certainly inherited. Every one knows how liable animals are to furious rage, and how plainly they show it. Many, and probably true, anecdotes have been published on the long-delayed and artful revenge of various animals. The accurate Eengger, and Brehm8 state that the American and African monkeys which they kept tame, certainly revenged themselves. Sir Andrew Smith, a zoologist whose scrupulous accuracy was known to many persons, told me the following story of which he was himself an eye-witness ; at the Cape of Good Hope an officer had often plagued a certain baboon, and the animal, seeing him approaching one Sunday for parade, poured water into a hole and hastily made some thick mud, which he skilfully dashed over the officer as he passed by, to the amusement of many bystanders. For long after- wards the baboon rejoiced and triumphed whenever he saw his victim. 6 For the evidence on this % All the following statements, kead, see Mr. J. Traherne Mog- given on the authority of these two gridge's most interesting work, naturalists, are taken from Rengger'a 4 Harvesting Ants and Trap-doer * Naturgesch. der S'augethiere voo Spiders/ 1873, p. 126, 128. , Paraguay/ 1830, s. 41-57, and froaa 7 * Recherches sur les MoDurs des Brehm's 'Thierleben/ B. i ». 10-37 Fourmis/ 1810, p. 173. 7® ~ The Descent of Man, Past I, The love of a dog for his master is notorious; as an old writer quaintly says,9 " A dog is the only thing on this earth " that luvs you more than he luvs himself/* In the agony of death a dog has been known to caress his master, and every one has heard of the dog suffering under vivisection, who licked the hand of the operator; this man, unless the operation was fully justified by an increase of our knowledge, or unless he had a heart of stone, must have felt remorse to the last hour of his life. As Whewell 10 has well asked, " who that reads the touching " instances of maternal affection, related so often of the women of " ail nations, and of the females of all animals, can doubt that the " principle of action is the same in the two cases ? " We see mater- nal affection 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 invariably caused the death of certain kinds kept under confinement by Brehm in N. Africa. Orphan monkeys were always adopted and carefully guarded by the other monkeys, both males and females. One female baboon had so capacious a heart that she not only adopted young monkeys of other species, but stole young dogs and cats, which she continually carried about. Her kindness, however, did not go so far as to share her food with her adopted offspring, at which Brehm was surprised, as his monkeys always divided everything quite fairly with their own young ones. An adopted kitten scratched this affectionate baboon, who certainly had a fine intellect, for she was much astonished at being scratched, and immediately examined the kitten's feet, and without more ado bit off the claws.11 In the Zoological Gardens, I heard from the keeper that an old baboon (0. chacma) had adopted a Bhesus 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 Bhesus and adopted both of them. The young Bhesus, 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 9 Quoted by Dr. Lauder Lindsay, 72), disputes the possibility of this in his ' Physiology of Mind in the act as described by Brehm, for the Lower Animals ;' ' Journal of Mental sake of discrediting my work. Science/ April 1871, p. 38. Therefore I tried, and found that I 10 * Bridgewater Treatise/ p. 263. could readily seize with my own 11 A crit^, without any grounds teeth the sharp little claws of a ('Quarterly Review.' July 1871, p. kitten nearly rive weeks old. Chap, III. Mental Powers. 71 whenever it could do so with safety ; this conduct exciting great indignation in the old baboon. Monkeys will also, according to Brehm, defend their master when attacked by any one, as well as dogs to whom they are attached, from the attacks of other dogs. But we here trench on the subjects of sympathy and fidelity, to which I shall recur. Some of Brehm's monkeys took much delight in teasing a certain old dog whom they disliked, as well as other animals, in various ingenious ways. Most of 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 shews that animals not only love, but have desire to be loved. Animals manifestly feel emulation. They love appro- bation or praise; and a dog carrying a basket for his master exhibits in a high degree self-complacency or pride. There can, I think, be no doubt that a dog feels shame, as distinct from fear, and something very like modesty when begging too often for food. A great dog scorns the snarling of a little dog, and this may be called magnanimity. Several observers have stated that monkeys certainly dislike being laughed at; and they sometimes invent imaginary offences. In the Zoological Gardens I saw a baboon who always got into a furious rage when his keeper took out a letter or book and read it aloud to him ; and his rage was so violent that, as I witnessed on one occasion, he bit his own leg till the blood flowed. Dogs show what may be fairly called a sense of humour, as distinct from mere play ; if a bit of stick or other such object be thrown to one, he will often carry it away for a short distance; and then squatting down with it on the ground close before him, will wait until his master comes quite close to take it away. The dog will then seize it and rush away in triumph, repeating the same manoeuvre, and evidently enjoying the practical joke. 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 Eengger, 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, for snakes; but their curiosity was so great that they could not desist from occasionally satiating /2 The Descent of Man. Pabt 1 tlieir horror in a most human fashion, by lifting up the lid of the box in which the snakes were kept. I was so much surprised at his account, that I took a stuffed and coiled-up snake into the monkey-house at the Zoological Gardens, and the excitement thus caused was one of the most curious spectacles which I ever beheld. Three species of Cercopithecus were the most alarmed ; they dashed about their cages, and uttered sharp signal cries of danger, which were understood by the other monkeys. A few young monkeys and one old Anubis baboon alone took no notice of the snake. I then placed the stuffed specimen on the ground in one of the larger compartments. After a time all the monkeys collected round it in a large circle, and staring intently, presented a most ludicrous appearance. They became extremely nervous ; so that when a wooden ball, with which they were familiar as a plaything, was accidentally moved in the straw, under which it was partly hidden, they all instantly started away. These monkeys behaved very differently when a dead fish, a mouse,12 a living turtle, and 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 compartments. One of the monkeys immediately approached, cautiously opened the bag a little, peeped in, and instantly dashed away. Then I witnessed what Brehm has described, for monkey after monkey, with head raised high and turned on one side, could not resist taking a momentary peep into the upright bag, at the dreadful object lying quietly at the bottom. It would almost appear as if monkeys had some notion of zoological affinities, for those kept by Brehm exhibited a strange, though mistaken, instinctive dread of innocent lizards and frogs. An orang, also, has been known to be much alarmed at the first sight of a turtle.13 The principle of Imitation is strong in man, and especially, as I have myself observed, with savages. In certain morbid states of the brain this tendency is exaggerated to an extraordinary degree ; some hemiplegic patients and others, at the commence- ment of inflammatory softening of the brain, unconsciously imitate every word which is uttered, whether in their own or in a foreign language, and every gesture or action which is per- formed near them.14 Desor15 has remarked that no animal 12 I have given a short account of Mammalia/ 1841, p. 405. cf their behaviour on this occasion 14 Dr. Bateman * On Aphasia, in my 'Expression of the Emotions,' 1870, p. 110. p. 43. 15 Quoted by Vogt, 'Memoire sm w W. C. L. Martin, « Nat. Hist, les Microcephales,' 1867, p. 168. Ship. III. Mental Powers. 73 voluntarily imitates an action performed by man, until in the ascending scale we come to monkeys, which are well known to l>e ridiculous mockers. Animals, however, sometimes imitate each other's actions : thus two species of wolves, which had been reared by dogs, learned to bark, as does sometimes the jackal,1'1 but whether this can be called voluntary imitation is another question. Birds imitate the songs of their parents, and some- times of other birds ; and parrots are notorious imitators of any sound which they often hear. Dureau de la Malle gives an account " of a dog reared by a cat, who learnt to imitate the well-known action of a cat licking her paws, and thus washing her ears and face; this was also witnessed by the celebrated naturalist Audouin. I have received several confirmatory ac- counts ; in one of these, a dog had not been suckled by a cat, but had been brought up with one, together with kittens, and had thus acquired the above habit, which he ever afterwards practised during his life of thirteen years. Dureau de la Malle's dog likewise learnt from the kittens to play with a ball by roll- ing it about with his fore paws, and springing on it. A corre- spondent assures me that a cat in his house used to put her paws into jugs of milk having too narrow a mouth for her head. A kitten of this cat soon learned the same trick, and practised it ever afterwards, whenever there was an opportunity. The parents of many animals, trusting to the principle of imitation in their young, and more especially to their instinctive or inherited tendencies, may be said to educate them. We see this when a cat brings a live mouse to her kittens; and Dureau de la Malle has given a curious account (in the paper above quoted) of his observations on hawks which taught their young dexterity, as well as judgment of distances, by first dropping through the air dead mice and sparrows, which the young generally failed to catch, and then bringing them live birds and letting them loose. Hardly any faculty is more important for the intellectual progress of man than Attention, Animals 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 engaged, that they may be easily approached. Mr. Bartlett has given me a curious proof how variable this faculty is in monkeys. A man who trains monkeys to act in plays, 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, 16 « The Variation of Animals aad 17 *Annales d«s Sc. Nat.' (1st Plants under Domestication,' vol. i. Series), torn, xxii p. 397. d. 27. 74 The Descent of Man Past I. if lie might keep three or four of them for a few days, in order to select one. When asked how he could possibly learn so soon, whether a particular monkey would turn out a good actor, he answered that it all depended on their power of attention. Jf, when he was talking and explaining anything 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 excellent Memories for persons and places. A baboon at the Cape of Good Hope, as I have been informed by Sir Andrew Smith, recognised 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 absence of five years and two days. I went near the stable where he lived, and shouted to him in my old manner ; he shewed no joy, but instantly followed me out walk- ing, 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 I8 has clearly shewn, recognised their fellow-ants belonging to the same community 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 former images and ideas, independently , of the will, and thus creates brilliant and novel fesults. A poet, as Jean Paul Richter remarks,19 " 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 in- " voluntary 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 combinations, and to a certain extent on our power of voluntarily combining them. As dogs, cats, horses, and probably all the higher animals, even birds20 have vivid dreams, and this is shewn by their movements and the sounds uttered, we must admit that they possess some 19 l Les Moeurs des Fourmis,' 2° Dr. Jerdon, * Birds of India, 1810, p. 150. vol. i. 1862, p. xxi. Houzeau say* 19 Quoted in Dr. Maudsley's ' Phy * that his parokeets and canary-birda Biology and Pathology of Mind,' 186S, dreamt: * Facultes Mentales*' torn pp. 19,220. ii. p. 136. £hap. III. Mental Powers, 75 bower of imagination. There must be something special, wliich tauses dogs to howl in the night, and especially during moonlight, in that remarkable and melancholy manner called baying. All dogs do not do so ; and, according to Houzeau,21 they do not then look at the moon, but at some fixed point near the horizon. Houzeau thinks that their imaginations are disturbed by the vague outlines of the surrounding objects, and conjure up before them fantastic images : if this be so, their feelings may almost be called superstitious. Of all the faculties of the human mind, it will, I presume, be admitted that Beason stands at the summit. Only a few persons now dispute that animals possess some power of reasoning. Animals may constantly be seen to pause, deliberate, and resolve. It is a significant fact, that the more the habits of any particular animal are studied by a naturalist, the more he attributes to reason and the less to unlearnt instincts.22 In future chapters we shall see that some animals extremely low in the scale appar- ently display a certain amount of reason. No doubt it is often difficult to distinguish between the power of reason and that of instinct For instance, Dr. Hayes, in his work on ' The Open Polar Sea/ repeatedly remarks that his dogs, instead of continu- ing to draw the sledges in a compact body, diverged and separ- ated when they came to thin ice, so that their weight might be more evenly distributed. This was often the first warning 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 instinct ? This instinctj may possibly have arisen since the time, long ago, when dogs were first employed by the natives in drawing their sledges ; or the Arctic wolves, the parent-stock of the Esquimaux dog, may have acquired an instinct, impelling them not to attack their prey in a close pack, when on thin ice. We can only judge by the circumstances under which actions are performed, whether they are due to instinct, or to reason, or to the mere association of ideas: this latter principle, however, is intimately connected with reason. A curious case has been given by Prof. Mobius,23 of a pike, separated by a plate of glass from an adjoining aquarium stocked with fish,- and who often dashed himself with such violence against the glass in trying to 21 * Faculty Mentales des Ani- I cannot help thinking, however, maux,' 1872, torn, ii, p. 181. that he goes too far in underrating 22 Mr. L. H. Morgan's work on the power of Instinct. * The American Beaver,' 1868, offers a* 'Die Bewegungen der Thiere, b goo Quoted by C. S. Wake, « Chap- teresting article, entitled ' Philo- ters on Man,' 1868, p. 101. logy and Darwinism' in * Nature/ 71 Buckland, ' Bridgewater Trea- March 24th, 1870, p. 528. tise/ p. 411. «» 'Nature/ Jan. 6th, 187C p. 257. 92 The Descent of Man. pAKr L borrowed expressive words and useful forms of construction from various conquering, conquered, or immigrant races. 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.72 Nor, as we have seen, does the faculty of articulate speech in itself offer any insuperable objection to the belief that man has been developed from some lower form. Sense of Beauty. — This sense has been declared to be peculiar to man. I refer here only to the pleasure given by certain colours, forms, and sounds, and which may fairly be called a sense of the beautiful ; with cultivated men such sensations are., however, intimately associated with complex ideas and trains of thought. When we behold a male bird elaborately displaying his graceful plumes or splendid colours before the female, whilst other birds, not thus decorated, make no such display, it is impossible to doubt that she admires the beauty of her male partner. As women everywhere deck themselves with these plumes, the beauty of such ornaments cannot be disputed. As we shall see later, the nests of humming-birds, and the playing passages of bower-birds are tastefully ornamented with gaily-coloured objects; and this shews that they must receive some kind of pleasure from the sight of such things. With the great majority of animals, however, the taste for the beautiful is confined, as far as we can judge, to the attractions of the opposite sex. The sweet strains poured forth by many male birds during the season of love, are certainly admired by the females, of which fact evidence will hereafter be given. If female birds had been incapable of appreciating the beautiful colours, the ornaments, and voices of their male partners, all the labour and anxiety exhibited by the latter in displaying their charms before the females would have been thrown away ; and this it is impossible to admit. Why certain bright colours should excite pleasure cannot, I presume, be explained, any more than why certain flavours and scents are agreeable ; but habit has something to do with the result, for that which is at first unpleasant to our senses, ultimately becomes pleasant, and habits are inherited. With respect to sounds, Helmholtz has explained to a certain extent on physiological principles, why harmonies and certain cadenees are agreeable. But besides this, sounds frequently recurring at irregular intervals are 72 See some good remarks on the J. Lubbock, * Origin of C.vilisaiicKOj simplification of languages, by Sir 1870, p. 273. Chap. III. Menial Powers. 93 highly disagreeable, as every one will admit who has listened at night to the irregular flapping of a rope on board ship. The same principle seems to come into play with vision, as the eye prefers symmetry or figures with some regular recurrence. Patterns of this kind are employed by even the lowest savages as ornaments; and they have been developed through sexual selection for the adornment of some male animals. Whether we can or not give any reason for the pleasure thus derived from vision and hearing, yet man and many of the lower animals are alike pleased by the same colours, graceful shading and forms, and the same sounds. The taste for the beautiful, at least as far as female beauty is concerned, is not of a special nature in the human mind; for it differs widely in the different races of man, and is not quite the same even in the different nations of the same race. Judging from the hideous ornaments, and the equally hideous music admired by most savages, it might be urged that their aesthetic faculty was not so highly developed as in certain animals, for instance, as in birds. Obviously no animal would be capable of admiring such scenes as the heavens at night, a beautiful land- scape, or refined music; but such high tastes are acquired through culture, and depend on complex associations ; they are not enjoyed by barbarians or by uneducated persons. Many of the faculties, which have been of inestimable service to man for his progressive advancement, such as the powers of the imagination, wonder, curiosity, an undefined sense of beauty, a tendency to imitation, and the love of excitement or novelty, could hardly fail to lead to capricious changes of customs and fashions. I have alluded to this point, because a recent writer73 has oddly fixed on Caprice " as one of the most remarkable and "typical differences between savages and brutes." But not only can we partially understand how it is that man is from various conflicting influences rendered capricious, but that the lower animals are, as we shall hereafter see, likewise capri- cious in their affections, aversions, and sense of beauty. There is also reason to suspect that they love novelty, for it own sake. 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 there is ample evidence, derived not from hasty travellers, but from men who have lccg resided with savages, that numerous races have existed, and still exist, who have no idea of one or more gods, and who have no « nes. 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,77 fear, reverence, gratitude, hope for the future, and perhaps other elements. No being could experience so complex an emotion anything which manifests power or " See an able article on the movement is thought to be endowed ' Physical Elements of Religion/ by with some form of life, and with Mr. L. Owen Pike, in * Anthropolet;, mental faculties analcgtr.is to our &»▼&»,' April, 1870, p. lxiii. own. q6 The Descent of Man. Part 1 until advanced in his intellectual and moral faculties to at least a moderately nigh level. Nevertheless, we see some distant approach to this state of mind in the d:ep love of a dog for his master, associated with complete submission, some fear, and perhaps other feelings. The behaviour of a dog when returning to his master after an absence, and, as I may add, of a monkey to his beloved keeper, is widely different from that towards their fellows. In the latter case the transports of joy appear to be somewhat less, and the sense of equality is shewn in every action. Professor Braubach goes so far as to maintain that a dog looks on his master as on a god.78 The same high mental faculties which first led man to believe in unseen spiritual agencies, then in fetishism, polytheism, and ultimately in monotheism, would infallibly lead him, as long as his reasoning powers remained poorly developed, to various strange superstitions and customs. Many of these are terrible to think of — such as the sacrifice of human beings to a blood- loving god ; the trial of innocent persons by the ordeal of poison or fire ; witchcraft, &c. — yet it is well occasionally to reflect on these superstitions, for they shew us what an infinite debt of gratitude we owe to the improvement of our reason, to science, and to our accumulated knowledge. As Sir J. Lubbock79 has well observed, " it is not too much to say that the horrible dread of " unknown evil hangs like a thick cloud over savage life, and " embitters every pleasure." These miserable and indirect consequences of our highest faculties may be compared with the incidental and occasional mistakes of the instincts of the lower animals. 78 ' Religion, Moral, &c, der Dar- T9 ' Prehistoric Times,* 2nd edit, win'schen Art-Lehre,' 1869, s. 53. p. 571. In this work (p. 571) It is said (Dr. W, Lauder Lindsay, there will be found an excellent 4 Jcurnal of Mental Science,* 1871, account of the many strange and p. 43), that Bacon long ago, and the capricious customs of savages, poe ; Burns, held the same notion. Ob at. \> Moral Setise. 97 CHAPTEE IV. COMrARISOS OF THE MENTAL POWERS OP MAN AND THE Lower Animals — continued. The moral sense — Fundamental proposition — The qualities of social animals — Origin of sociability— Struggle between opposed instincts — Man a social animal — The more enduring social instincts conquer other less persistent instincts — The social virtues alone regarded by savages — The self-regarding virtues acquired at a later stage of development — The importance of the judgment of the members of the same community on conduct — Transmission of moral tendencies — Summary. I fully subscribe to the judgment of those writers1 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 Mackintosh2 remarks, " has a\ " rightful supremacy over every other principle of human "action;" it is summed up in that short but imperious word ougJit, so full of high significance. It is the most noble of all the attributes of man, leading him without a moment's hesita- tion to risk his life for that of a fellow-creature ; or after due deliberation, impelled simply by the deep feeling of right or duty, to sacrifice it in some great cause. Immanuel Kant exclaims, " Duty ! Wondrous thought, that workest neither by " fond insinuation, 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 appetites are dumb, however secretly they rebel ; " whence thy original ?"8 This great question has been discussed by many writers4 of consummate ability ; and my sole excuse for touching on it, is the impossibility of here passing it over ; and because, as far as I know, no one has approached it exclusively from the side of natural history. The investigation possesses, also, some in- 1 See, for instance, on this subject, and Moral Science,' 1868, p. 543- Quatrefages, * Unite' de PEspece 725) of twenty-six British authors Humaine,' 1861, p. 21, &c. who have written on this subject, 2 * Dissertation on Ethical Philo- and whose names are familiar to sophy,' 1837, p. 231, &c. every reader ; to these, Mr. Bain's s 4 Metaphysics of Ethics,' trans- own name, and those of Mr. Lecky, lated by J. W. Semple, Edinburgh, Mr. Shadworth Hodgson, Sir J. ;836, p. 136. Lubbock, and others, might be * Mr. Bah gives a list (' Mental added. 98 The Descent of Man. Part I dopendont interest, as an attempt to see how far the study of the lower animals throws light on one of the highest psychical faculties of man. The following proposition seems to me in a high degree probable — namely, that any animal whatever, endowed with well-marked social instincts,6 the parental and filial affections being here included, would inevitably acquire a moral sense or conscience, as soon as its intellectual powers had become as well, \ or nearly as well developed, as in man. For, firstly, the social instincts lead an animal to take pleasure in the society of its fellows, to feel a certain amount of sympathy with them, and to perform various services for them. The services may be of a definite and evidently instinctive nature ; or there may be only a wish and readiness, as with most of the higher social animals,, to aid .their, fellows in certain general ways. But these feelings and services are by no means extended to all the individuals of the same species, only to those of the same association. Secondly , as soon as the mental faculties had become highly developed, images of all past actions and motives would be incessantly passing through the brain of each individual ; and that feeling of dissatisfaction, or even misery, which invariably results, as we shall hereafter see, from any unsatisfied instinct, would arise, as often as it was perceived that the enduring and always present social instinct had yielded to some other instinct, at the time stronger, but neither enduring in its nature, nor leaving 5 Sir B. Brodie, aftei observing all this, he also remarks, " if, as is that man is a social animal (' Psy- " my own belief, the moral feelings chological Enquiries/ 1854, p. 192), " are not innate, but acquired, they asks the pregnant question, " ought " are not for that reason less natu- " not this to settle the disputed " ral." It is with hesitation that I " question as to the existence of a venture to differ at all from so " moral sense ?" Similar ideas have profound a thinker, but it can probably occurred to many persons, hardly be disputed that the social as they did long ago to Marcus feelings are instinctive or innate in Aurelius. Mr. J. S. Mill speaks, in the lower animals ; and why should his celebrated work, * Utilitarian- they not be so in man ? Mr. Bain ism,' (1864, pp. 45, 46), of the social (see, for instance, 'The Emotions and feelings as a "powerful natural the Will,' 1865, p. 481) and others " sentiment," and as " the natural believe that the moral sense is ac- " basis of sentiment for utilitarian quired by each individual during " morality." Again he says, " Like his lifetime. On the general theory " the other acquired capacities above of evolution this is at least ex- " referred to, the moral faculty, if tremely improbable. The ignoring " not a part of our nature, is of all transmitted mental qualities *' a natural out-growth from it ; will, as it seems to me, bo hereafter *4 capable, like them, in a certain judged as a most serious blemish ia *' small degree of springing up spon- the works of Mr. Mill. '* taiieonsly." But in opposition to Chap. IV. Moral Sense, 9g behind it a very vivid impression. It is clear that many in- stinctive desires, such as that of hunger, 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 community could be expressed, I the common opinion how each member ought to act for the | public good, would naturally become in a paramount degree Ithe guide to action. But it should be borne in mind that how- ever great weight we may attribute to public opinion, our regard for the approbation and disapprobation of our fellows depends ' \ on sympathy, which, as we shall see, forms an essential part of the social instinct, and is indeed its foundation-stone, Lastly, \ habit in the individual would ultimately play a very important \ part in guiding the conduct of each member; for the social in- \ stinct, together with sympathy, is, like any other instinct, greatly strengthened by habit, and so consequently would be obedience to the wishes and judgment of the community. These several subordinate propositions must now be discussed, and some of them at considerable length. f It may be well first to premise that I do not wish to maintain that any strictly social animal, if its intellectual faculties were to become as active and as highly developed as in man, would acquire exactly the same moral sense as ours. In the same manner as various animals have some sense of beauty, though they admire widely different objects, so they might have a sense of right and wrong, though led by it to follow widely different lines of conduct. If, for instance, to take an extreme case, men were reared under precisely the same conditions as hive-bees, there can hardly be a doubt that our unmarried females would, like the worker-bees, think it a sacred duty to kill their brothers, and mothers would strive to kill their fertile daughters ; and no 4 one would think of interfering.6 Nevertheless, the bee, or any 6 Mr. H. Sidgwick remarks, in in Morals,* 'Theological Review, an able discussion on this subject April, 1872, p. 188-191) on the (the * Academy/ June 15th, 1872, same illustration, says, the prin- (p. 231), "a superior bee, we may ciples of social duty would be thus " feel sure, would aspire to a milder reversed ; and by this, I presume, " solution of the population ques- she means that the fulfilment of a " tion." Judging, however, from social duty would tend to the injury the habits of many or most savages, of individuals ; but she overlooks man solves the problem by female the fact, which she would doubtless infanticide, polyandry and promis- admit, that the instincts of the bee cuous intercourse ; therefore it may have been acquired for the good of well be doubted whether it would the community. She goes so far as be by a milder method. Miss to say that if the theory of ethics Cobbf, in commenting (* Darwinism advocated hi this chapter were ever • H 2 loo TJie Descent of Man. Tart I. other social animal, would gain in our supposed case, as i«t appears to me, some feeling of right or wrong, or a conscience. For each individual would have an inward sense of possessing certain stronger or more enduring instincts, and others less strong or enduring ; so that there would often be a struggle as to which impulse should be followed; and satisfaction, dissatis- faction, or even misery would be felt, as past impressions were compared during their incessant passage through the mind. In this case an inward monitor would tell the animal that it would have been better to have followed the one impulse rather than the other. The one course ought to have been followed, and the other ought not ; the one would have been right and the other wrong ; but to these terms I shall recur. Sociability. — Animals of many kinds are social ; we find even distinct species living together ; for example, some American monkeys ; and united flocks of rooks, jackdaws, and starlings Man shews the same feeling in his strong love for the dog, which the dog returns with interest. Every one must have noticed ho* miserable horses, dogs, sheep, &c, are when separated from their companions, and what strong mutual affection the two former kinds, at least, shew 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 confine our attention to the higher social animals ; and pass over insects, although some of these are social, and aid one another in man;? important ways. T^,m£sJL-£Oinitto^^ higher animalsis to warn one jgiothev of dn.ngpr by mpa^ <$}/ theunited^nses^oTalir Every sportsman knows, as Dr. Jaeger remarks,7 how difficult it is to approach animals in a herd or troop. Wild horses and cattle do not, I believe, make anj danger-signah but the attitude of any one of them who first discovers an enemy, warns the others. Babbits stamp Joudly on the ground with their hind-feet as a signal : sheep and ohamois do the same with their forefeet, uttering likewise a whistle. Many birdsr and some mammals, post sentinels^wJiicJlJr. Jhe(j) a^geofjfeals are said8 generally to be_the_females. The leader generally accepted, " I cannot but earth is not held by many persons '* believe that in the hour of their on so weak a tenure. " triumph would be sounded the 7 * Die Darwin'sche Theorie," s 44 knell of the virtue of mankind!" 101. 5t is to h« hoped that the belief in 8 Mr. R. Brown in * Proc. Zooiog, the permanence of virtue on this Soc,' 1868, p. 409. Chap. IV. Moral Sense. 101 of a troop of monkeys acts as the sentinel, and utters cries expressive both of danger and of safety.9 Social animals perform many little services for each other : horses nibble,and cows lick each other, on any spot which itches: monkeys search each other for external parasites ; and Brehm states that after a troop <£> of the Cercopitkecus griseo-viridls 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 morejimjgorta^^ : thus woTvelT and some _other~T)easts of prjff hjratjin jpacksjand q^ aid "one another "IrTattacking their victims. Pelicans fish ir; concert. The Hamacfryas baboons turn over stones to find insects, &c. ; and when they come to a large one, as many as can stand round, turn it over together and share the booty. Social ~^ animals mutually defend eachjriher. Bull bisons in N. America* vP when there is danger, drive the cows and calves into the middle of the herd, whilst they defend the outside. I shall also in a future chapter give an account of two young wild bulls at Chillingham attacking an old one in concert, and of two stallions together trying to drive away a third stallion from a troop of mares. In Abyssinia, Brehm encountered a great troop of baboons, who were crossing a valley : some had already ascended the opposite mountain, and some were still in the valley : the latter were attacked by the dogs, but the old males immediately hurried down from the rocks, and with mouths widely opened, roared so fearfully, that the dogs quickly drew back. They were again encouraged to the attack ; but by this time all the 1 baboons had reascended the heights, excepting a young one, about six months old, who, loudly calling for aid, climbed on a block of rock, and wai surrounded. Now one of the largest f 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, 9 Bvehm, ' Thierleben,' B. i. 1864, the evidence of Alvarez, whose ob- s. 52, 79. For the case of the serrations Brehm thinks quite trust- monkeys extracting thorns from worthy. For the cases of the old each other, see s. 54. With respect male baboons attacking tne dogs, to the Hamadryas turning over see s. 79; and with respect to thf stones, tfe fact is given (s. 76) on y led by the hope of receiving good in return to perform acts _y WcaL\ - oT" sympathetic kindness to others; and sympathy^is much strengthened by habit. In however complex a manner this"""^ feeling may have originated, as it is one of high importance to j all those animals which aid and defend one another, it will havo I been increased through natural selection ; for those commu- / nities, which included the greatest number of the most sympa- ( thetic members, would flourish best, and rear the greatest \ number of offspring. ~— ) It is, however, impossible to decide in many cases whether certain social instincts have beon acquired through natural selection, or are the indirect result of other instincts and faculties, such as sympathy, reason, experience, and a tendency to imitation ; or again, whether they are simply the result of long-continued habit. So remarkable an instinct as the placing sentinels to warn the community of danger, can hardly have been the indirect result of any of these faculties ; it must, there- fore, have been directly acquired. On the other hand, the habit followed by the males of some social animals of dfiffrndi^g foft community, and of attacking their enemies or their-^may in concert, may~perhaps have originated from mutual sympathy ; but courage7~and in most "cases strength, "must have been previousIy~acquired, probably through natur^selectionT""^ Of the various instincts and habits, some~are much stronger than others ; that is, some either give more pleasure in their performance, and more distress in their prevention, than others ; or, which is probably quite as important, they are, through inheritance,, more persistently followed, without exciting any special feeling of pleasure or pain. "We are ourselves conscious that some habits are much more difficult to cure or change than others. Hence a struggle may often be observed in animals between different instincts, or between an instinct and some habitual disposition ; as when a dog rushes after a hare, is rebuked, pauses, hesitates, pursues again, or returns ashamed to his master ; or as between the love of a female dog for her young puppies and for her master,— for she may be seen to slink away to them, as if half ashamed of not accompanying her master. But the most curious instance known to me of one instinct getting the better of another, is the migratory instinct conquer- ing the maternal instinct. The former is wonderfully strong ; a confined bird will at the proper season beat her breast against the wires of her cage, until it is bare and bloody. It causes young salmon to leap out of the fresh water, in which they could loS x The Descent of Man, Past I. continue to exist, and thus unintentionally to commit suicide. Every one knows how strong the maternal instinct is, leading even timid birds to face great danger, though with hesitation, and in opposition to the instinct of self-preservation. Neverthe- less, the migratory instinct is so powerful, that late in the autumn swallows, house-martins, and swifts frequently desert their tender young, leaving them to perish miserably in their nests.53 We can perceive that an instinctive impulse, if it be in any way more beneficial to a species than some other or opposed instinct, would be rendered the more potent of the two through natural selection ; for the individuals which had it most strongly developed would survive in larger numbers. Whether this is the case with the migratory in comparison with the maternal instinct, may be doubted. The great persistence, or steady action of the former at certain seasons of the year during the whole day, may give it for a time paramount force. Man a social animal. — Every one will admit that man is a social being. We see this in his dislike of solitude, and in his wish for society beyond that of his own family. Solitary con- finement is one of the severest punishments which can be inflicted. Some authors suppose that man primevally lived in single families ; but at the present day, though single families, or only two or three together, roam the solitudes of some savage lands, they always, as far as I can discover, hold friendly relations with other families inhabiting the same district. Such families occasionally meet in council, and unite for their common defence. It is no argument against savage man being a social animal, that the tribes inhabiting adjacent districts are almost always at war with each other ; for the social instincts nevei extend to all the individuals of the same species. Judging from the analogy of the majority of the Quadrumana, it is probable that the early ape-like progenitors of man were likewise social ; but this is not of much importance for us. Although man, as 22 This fact, the Rev. L. Jenyns hatched. Many birds, not yet old states (see his edition of 4 White's enough for a prolonged flight, are Nat. Hist, of Selborne,' 1853, p. likewise deserted and left behind. 204) was first recorded by the illus- See Blackwall, * Researches in Zoo- trious Jenner, in * Phil. Transact.* logy,' 1834, pp. 108, 118. For some 1824, and has since been confirmed additional evidence, although this by several observers, especially by is not wanted, see Leroy, 4 Lettres Mr. Blackwall. This latter careful Phil/ 1802, p. 217. For Swifts, observer examined, late in the Gould's 'Introduction to the Birds autumn, during two years, thirty- of Great Britain,' 1823, p. 5. Simi- six nests ; he found that twelve lar cases have been observed in contained young dead birds, five Canada by Mr. Adams ; ' Pop, contained eggs on the point of being Science Review,' July 1873, p. hatched, and three, aggs not nearly 283. Chap. IV, Moral Sense. log 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 extremely remote period some degree of instinctive love and sympathy for his fellows. We are indeed all conscious that we do possess such sympathetic feelings ; ** but our consciousness does not tell 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 aJmxMftjcertaj^^ be faKhful to his comrades, and obedient to the leader of his tribe ; for these qualities are common to most social animals, lie would consequently possess some capacity for self-command. He would from an inherited tendency be willing to defend, in concert with others^ his fellow-menl"an3rwould be read£ Jo aid them in any way, which did not too greatly interfere with his own weTIare or his own strong desires. The social animals which stalidTaTthe bottom of the scale are guided almost exclusively, and those which stand higher in the scale are largely guided, by special instincts in the aid which they give to the members of the same community; but they 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 intellectual faculties would naturally be much guided in this respect by reason and experience. Instinctive sympathy would also cause him to value highly the approbation of his fellows ; for, as Mr. Bain has clearly shewn,24 the love of praise and the strong feeling of glory, and the still stronger horror of scorn and infamy, " are due to the workings of sympathy." Conse- quently man would be influenced in the highest degree by the wishes, approbation, and blame of his fellow-men, as expressed by their gestures and language. Thus the social instincts, which must have been acquired by man in a very rude state, and probably even by his early ape-like progenitors, still give the impulse to some of his best actions ; but his actions are in a higher degree determined by the expressed wishes and judgment 23 Hume remarks (' An Enquiry " of the former . . . communicates Concerning the Principles of Morals/ "a secret joy ; the appearance ol edit, of 1751, p. 132), "There seems " the latter . . . throws a melan- «' a necessity for confessing that the " choly damp over the imagina- " happiness and misery of others " tion." u are not spectacles altogether in- 2# * Mental and Moral Science, «• different to us, but that the view 1863, p. 254- I IO The Descent of Man. Part L of his fellow-men, and unfortunately very often by his own strong selfish desires. But as love, sympathy and self-command become strengthened by habit, and as the power of reasoning becomes clearer, so that man can value justly the judgments of his fellows, he will feel himself impelled, apart from any transitory pleasure or pain, to certain lines of conduct. He might then declare — not that any barbarian or uncultivated man could thus think — I am the supreme judge of my own conduct, and in the words of Kant, I will not in my own person violate the dignity of humanity. The more enduring Social Instincts conquer the less persistent Instincts. — We have not, however, as yet considered the main point, on which, from our present point of view, the whole question of the moral sense turns. Why should a man feel that he ought to obey one instinctive desire rather than another? Why is he bitterly regretful, if he has yielded to a strong sense of self-preservation, and has not risked his life to save that of a fellow-creature ? or why does he regret having stolen food from hunger ? # It jj evident in thqiLratJDla.c^ that mtlLmj^nMndthe instinc- tive impulses have different degrees of strength ; a savage will risk his own life to save that oL amember of the same community, but wjlljse ijvhonxin^fferent about a stranger: a young and timid mother urged by the maternal instinct will, without a moment's hesitation, run the greatest danger for her own infant, but not for a mere fellow-creature. Nevertheless many a civilized man, or even boy, who never before risked his life for another, but full of courage and sympathy, has diregarded the instinct of self-preservation, and plunged at once into a torrent to save a drowning man, though a stranger. In this case man is impelled by the same instinctive motive, which made the heroic little American monkey, formerly described, save his keeper, by attacking the great and dreaded baboon. Such actions as the above appear to be the simple result of the greater strength of the social or maternal instincts than that of any other instinct or motive; for they are performed too instan- taneously for reflection, or for pleasure or pain to be felt at the time ; though, if prevented by any cause, distress or even misery might be felt. In a timid man, on the other hand, the instinct of self-preservation might be so strong, that he would be unable to force himself to run any such risk, perhaps not even for his own child. I am aware that some persons maintain that actions performed impulsively, as in the above cases, do not come under the doinizion of the moral sense, and cannot b€ called moral. The^ Ohap. IV. Moral Sense. ill confine this term to actions done deliberately, after a victory over opposing desires, or when prompted by some exalted motive. But it appears scarcely possible to draw any clear line of distinction of this kind.25 Ajs far as exalted motives are concerned, many instances have been recorded of savages, destitute of any feeling of general benevolence towards mankind and not guided by any religious motive, who have deliberately sacrificed their lives as prisoners,26 rather than betray their comra3e§.; and surely their conduct ougEFto^W:X!OnldaeTOtTnr moral. As far as deliberation, and the victory over opposiDg motives are concerned, animals may be seen 3TouBlmgn5itween opposed ins line Ls, in resn ' 1£70, p. 353 Sept. 15, 1869 ; and more fully r Ceap. IV, Moral Sense. 121 or habits, experience unfortunately shews us how long it is, before we look at them as our fellow-creatures. Sympathy beyond the confines of man, that is, humanity to the lower animals, seems to be one of the latest moral acquisitions. It is apparently unfelt by savages, except towards their pets. How little the old Eomans knew of it is shewn 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 sympathies becoming more tender and more widely diffused, until they are extended to all sentient beings. As soon as this virtue is honoured and practised by some few men, it spreads through instruction and example to the young, and eventually becomes incorporated in public opinion. The highest possible stage in moral culture is when we re- cognise that 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."44 Whatever makes any bad action familiar to the mind, renders its performance by so much the easier. As Marcus Aurelius long ago said, "Such as are thy habitual " thoughts, such also will be the character of tby mind ; for the " soul is dyed by the thoughts."45 Our great philosopher, Herbert Spencer, has recently explained his views on the moral sense. He says,46 "I believe that the " experiences of utility organised and consolidated through all " past generations of the human race, have been producing " corresponding modifications, which, by continued transmission " and accumulation, have become in us certain faculties of " moral intuition— certain emotions responding to right and " wrong conduct, which have no apparent basis in the individual " experiences of utility." There is not the least inherent improbability, as it seems to me, in virtuous tendencies being more or less strongly inherited ; for, not to mention the various dispositions and habits transmitted by many of our domestic animals to their offspring, I have heard of authentic cases in which a desire to steal and a tendency to lie appeared to run in families of the upper ranks ; and as stealing is a rare crime i*\ the wealthy classes, we can hardly account by accidental coinci- dence for the tendency occurring in two or three members of 44 Tennyson, ' Idylls of the King,' Aurelius was born A.D. 121. p. 244. 46 Letter to Mr. Mill in Bain's 45 * The Thoughts of the Emperor * Mental and Moral Science/ 1 868 M. Aurelius Antoninus," Eng. trans- p. 722. hU 2nd edit,, 1869, p. 112. Mavcis 124 The Descent of Man. Part! the same family. If bad tendencies are transmitted, it is pro- bable that good ones are likewise transmitted. That the state of the body by affecting the braiij, has great influence on the moral tendencies is known to most of those who have suffered from chronic derangements of the digestion or liver. The same fact is likewise shewn by the " perversion or destruction of the " moral sense being often one of the earliest symptoms of mental *f derangement;"47 and insanity is notoriously often inherited. Except through the principle of the transmission of moral ten- dencies, we cannot understand the differences believed to exist in this respect between the various races of mankind. Even the partial transmission of virtuous tendencies would be an immense assistance to the primary impulse derived directly and indirectly from the social instincts. Admitting for a moment that virtuous tendencies are inherited, it appears probable, at least in such cases as chastity, temperance, humanity to animals, &c, that they become first impressed on the mental organization through habit, instruction and example, continued during several generations in the same family, and in a quite subordinate degree, or not at all, by the individuals possessing such virtues havmg_jn£CJ3£ded best in the struggle for fife. ISrychief source of doubt with respect to any such inheritance, is that senseless customs, superstitions, and tastes, such as the horror of a Hindoo for unclean food, ought on the same principle to be transmitted. I have not met with any evidence in support of the transmission of superstitious customs or senseless habits, although in itself it is perhaps not less probable than that animals should acquire inherited tastes for certain kinds of food or fear of certain foes. Finally the social instincts, which no doubt were acquired 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, some feeling of sympathy, and have compelled him to regard their approbation and disapprobation. Such impulses will have served him at a very early period as a rude rule of right and wrong. But as man gradually advanced in intellectual power, and was enabled to trace the more remote consequences of his actions; as he acquired sufiicient knowledge to reject baneful customs and superstitions; as he regarded more and more, not only the welfare, but the happiness of his fellow-men ; as from habit, following on beneficial experience, instruction and example, his sympathies became more tender and widely diffused, extending to men of all races, to the imbecile, maimedf 47 Maudsley, ' Body and Mind,' 1870, p. 60. Chap. IV. Summary. t2£ and other useless members of society, and finally to the lower animals, — so would the standard of his morality rise higher and higher. And it is admitted by moralists of the derivative school and by some intuitionists, that the standard of morality has risen since an early period in the history of man.48 As a struggle may sometimes be seen going on between the various instincts of the lower animals, it is not surprising that there should be a struggle in man between his social instincts, with their derived virtues, and his lower, though momentarily stronger impulses or desires. This, as Mr. Galton49 has remarked, is all the less surprising, as man has emerged from a state of barbarism within a comparatively recent period. After having yiolded to some temptation we feel a sense of dissatisfaction, shame, repentance, or remorse, analogous to the feelings caused by other powerful instincts or desires, when left unsatisfied or baulked. We compare the weakened impression of a past temptation with the ever present social instincts, or with habits, gained in early youth and strengthened during our whole lives, until they have become almost as strong as instincts. If with the temptation still before us we do not yield, it is because either the social instinct or some custom is at the moment predominant, or because we have learnt that it will appear to us hereafter the stronger, when compared with the weakened im- pression of the temptation , and we realise that its violation would cause us suffering. Looking to future generations, there is no cause to fear that the social instincts will grow weaker, and we may expect that virtuous habits will grow stronger, becoming perhaps fixed by inheritance. In this case the struggle between our higher and lower impulses will be less severe, and virtue will be triumphant. Summary of the last two Chapters. — There can be no doubt that the difference between the mind of the lowest man and that of the highest animal is immense. An anthropomorphous ape, if he could take a dispassionate view of his own case, would admit that though he could 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 48 A writer in the * North British coincide therein. Review* (July 1869, p. 531), well *9 See his remarkable work on capable of forming a sound judg- * Hereditary Geni»\s/ 1869, p. 349. ment, expresses himself strongly in The Duke of Argyll (* Primeval favour of this conclusion. Mr. Man/ 1869, p. 188) has some good Lecky (* Hist, of Morals/ vol. i. p. remarks on the contest in man'i 143) seems to a certain extent to nature between right and wrong. i 26 The Descent of Man. Vkm I. qui to Uiyond 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 GdS, or admire a grand natural scene. Some apes, however, would probably declare that they could and did admire the beauty of the coloured skin and fur of their partners in marriage. They would admit, that though they could make other apes understand by cries some of their per- ceptions and simpler wants, the notion of expressing definite ideas by definite sounds had never crossed 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 acknow- ledge that disinterested love for all living creatures, the mos4, noble attribute of man, was quite beyond their comprehension. Nevertheless the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind. We have seen that the senses and intuitions, the various emotions and faculties, such as love, memory, attention, curiosity, imitation, reason, &c, of which man boasts, may be found in an incipient, or even sometimes in a well- developed condition, in the lower animals. They are also capable of some inherited improvement, as we see in the domestic dog compared with the wolf or jackal. If it could be proved that certain high mental powers, such as the formation of general concepts, self-con- sciousness, &c, were absolutely peculiar to man, which seems extremely doubtful, it is not improbable that these qualities are merely the incidental results of other highly-advanced intel- lectual faculties; and these again mainly the result of the continued use of a perfect language. At what age does the new-born infant possess the power of abstraction, or become self-conscious, and reflect on its own existence ? We cannot answer ; nor can we answer in regard to the ascending organic scale. The half-art, half-instinct of language still bears the stamp of its gradual evolution. The ennobling belief in God is not universal with man; and the belief in spiritual agencies naturally follows from other mental powers. The moral sense perhaps affords the best and highest distinction between man and the lower animals ; but I need say nothing on this head, as I have so lately endeavoured to shew that the social instincts, — the prime principle of man's moral constitution 5t> — with the aid of active intellectual powers and the effects of habit, naturally lead to the golden rule, " As ye would that men should do to you, do ye to them likewise ;" and this lies at the foundation of morality •• ' The Thoughts of Marcus Aurelius/ &c, p. 139, h EttA*. V, f Intellectual Faculties. 12J In the next, 'Chapter I shall malie some few remarks on the probable gieps and means by which the several mental and moral faculties of man have been gradually evolved. That such evolu- tion is at least possible, ought not to be denied, for we daily see these faculties developing in every infant ; and we may trace a perfect gradation from the mind of an utter idiot, lower than that of an animal low in the scale, to the mind of a Newton. CHAPTEE V. On the Development of the Intellectual and Moral Faculties during Primeval and Civilised Times. 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 affecting civilised nations — Evidence that civilised nations were once barbarous. The subjects to be discussed in this chapter are of the highest interest, but are treated by me in an imperfect and fragmentary manner. Mr. Wallace, in an admirable paper before referred to,1 argues that man, after he had partially acquired those intel- tectual and moral faculties which distinguish him from the lower animals, would have been but little liable to bodily modifications through natural selection or any other means. For man is enabled through his mental faculties " to keep with " an unchanged body in harmony with the changing universe." He has great power of adapting his habits to new conditions of life. He invents weapons, tools, and various stratagems to procure food and to defend himself. When he migrates into a colder climate he uses clothes, builds sheds, and makes fires; and by the aid of fire cooks food otherwise indigestible. He aids his fellow-men in many ways, and anticipates future events. Even at a remote period he practised some division of labour. The lower animals, on the other hand, must have their bodily structure modified in order to survive under greatly changed conditions. 'They must be rendered stronger, or acquire more effective teeth or claws, for defence against new enemies ; or they must be reduced in size, so as to escape detection and danger. When they migrate into a colder climate, they must become clothed with thicker fur, or have their constitutions altered. If they fail to be thus modified, they will cease to exist. ^.^ * * Anthropological Review,* May 1864, p. clviii. [ 28 The Descent of Man} ^ pAat J, The case, however, is widely different, as ^ Wallace haa 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 progenitors, they would have been perfected or advanced through natural selection. Of the high importance of the intellectual faculties there can be no doubt, for man mainly owes to them his predominant position in the world. We can see, that in the rudest state of society, the individuals who were the most sagacious, who invented and used the best weapons or traps, and who were best able to defend themselves, would rear the greatest number of offspring. The tribes, which included the largest number of men thus endowed, would increase in number and supplant other tribes. Numbers depend primarily on the means of subsistence, and this depends partly on the physical nature of the country, but in a much higher degree on the arts which are there practised. As a tribe increases and is victorious, it is often still further increased by the ab- sorption of other tribes.2 The stature and strength of the men of a tribe are likewise of some importance for its success, and these depend in part on the nature and amount of the food which can be obtained. In Europe the men of the Bronze period were supplanted by a race more powerful, and, judging from their sword-handles, with larger hands ;s but their success was pro- bably still more due to their superiority m the arts. All that we know about savages, or may infer from their traditions and from, old monuments, the history of which is quite forgotten by the present inhabitants, shew that from the remotest times successful tribes have supplanted other tribes. Relics of extinct or forgotten tribes have been discovered throughout tho civilised regions of the earth, on the wild plains of America, and on the isolated islands in the Pacific Ocean. At the present day civilised nations are everywhere supplanting barbarous nations, excepting where the climate opposes a deadly barrier ; and they succeed mainly, though not exclusively, through their arts, which are the prod ucts of the intellect. It is, therefore, highly probable that with mankind the intellectual faculties have been mainly and gradually perfected through natural selection ; and this con- clusion is sufficient for our purpose. Undoubtedly it would be interesting to trace the development of each separate faculty 2 After a time the members or 1861, p. 131), that they are the co- tribes whici are absorbed into descendants of the same ancestor?, another tribe assume, as Sir Henry 3 Morlot, * Sop. Vaud. Sc. Nat. Maine remarks ('Ancient Law/ I860, p. 294. Chap. V. Moral Faculties. 129 from the state in which it exists in the lower animals to that in which it exists in man; but neither my ability nor knowledge permits the attempt. It deserves notice that, as soon as the progenitors of man became social (and this probably occurred at a very earlyperiod), the principle of imitation* and reason, and experience would have increased, and much modified the intellectual powers in a way, of which we see only traces in the lower animals. Apes are much given to imitation, as are the lowest savages; and the simple fact previously referred to, that after a time no animal can be caught in the same place by the same sort of trap, shews that animals learn by experience, and imitate the caution of others. Now, if some one man in a tribe, more sagacious than the others, invented a new snare or weapon, or other means of attack or defence, the plainest self-interest, without the assistance of much reasoning power, would prompt the other members to imitate him ; and all would thus profit. The habitual practice of each new art must likewise in some slight degree strengthen the intellect. If the new invention were an important one, the tribe would increase in number, spread, and supplant other tribes. In a tribe thus rendered more numerous there would always be a rather greater chance of the birth of other superior and inventive members. If such men left children to inherit their mental superiority, the chance of the birth of still more ingenious members would be somewhat better, and in a very small tribe decidedly better. Even if they left no children, the tribe would still include their blood- relations ; and it has been ascertained by agriculturists * that by preserving and breeding from the family of an animal, which when slaughtered was found to be valuable, the desired character has been obtained^ Turning now to the social and moral faculties. In order that primeval men, or the ape-like pregenitors of man, should become social, they must have acquired the same instinctive feelings, which impel other animals to live in a body ; and they no doubt exhibited the same general disposition. They would have felt uneasy when separated from their comrades, for whom they would have felt some degree of love; they would have warned each other of danger, and have given mutual aid in attack or defence. All this implies some degree of sympathy, fidelity, and courage. Such social qualities, the paramount importance of which to the lower animals is disputed by no one, were no doubt 4 1 have given instances in my ' Variation of Animals under Domestica- tion,* vol. ii. p. 196. 130 The Descent of Man. Part I. acquired by the progenitors of man in a similar manner, namely, through natural selection, aided by inherited habit. When two tribes of primeval man, living in the same country, came into competition, if (other circumstances being equal) the one tribe included a great 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 succeed better 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 undis- ciplined hordes follows chiefly from the confidence which each man feels in his comrades. Obedience, as Mr. Bagehot has well shewn,5 is of the highest value, for any form of government is better than none. Selfish and contentious people will not cohere, and without coherence nothing can be effected. A tribe rich in the above qualities would spread and be victorious over othei tribes : but in the course of time it would, judging from all past history, be in its turn overcome by some other tribe still more highly endowed. Thus the social and moral qualities would tend slowly to advance and be diffused throughout the world. JBut it may be asked, how within the limits of the same tribe did a large number of members first become endowed with these social and moral qualities, and how was the standard of ex- cellence raised ? It is extremely doubtful whether the offspring of the more sympathetic and benevolent parents, or of those who were the most faithful to their comrades, would be reared in greater numbers than the children of selfish and treacherous parents belonging to the same tribe. He who was ready to sacrifice his life, as many a savage has been, rather than betray his comrades, would often leave no offspring to inherit his noble nature. The bravest men, who were always willing to come to the front in war, and who freely risked their lives for others, would on an average perish in larger numbers than other men. Therefore it hardly seems probable, that the" number of men gifted with such virtues, or that the standard of their excellence, could be increased through natural selection, that is, by the survival of the fittest ; for we are not here speaking of one tribe being victorious over another. Although the circumstances, leading to an increase in the number of those thus endowed within the same tribe, are too complex to bo clearly followed out, we can trace some of the probable steps, in the first place, as the reasoning powers and a See a remarkable series of arti- April 1, 1868 ; July 1, 1869, siac* clee on ' Physics and Politics ' in the separately published. • Fortnightly Review." Ko*\ 1 $67 ; Chap. V. Moral Faculties. 131 foresight of the members became improved, each man would soon learn 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 actions. Habits, moreover, followed during many generations probably tend to be inherited. But another and much more powerful stimulus to the de- velopment of the social virtues, is afforded by the praise and the blame of our fellow-men. To the instinct of sympathy, as we have already seen, it is primarily due, that we habitually bestow both praise and blame on others, whilst we love the former and dread the latter when applied to ourselves; and this instinct no doubt was originally acquired, like all the other social instincts, through natural selection. At how early a period the progenitors of man in the course of their development, became capable of feeling and being impelled by, the praise or blame of their fellow-creatures, we cannot of course say. But it appears that even dogs appre- ciate encouragement, praise, and blame. The rudest savages feel the sentiment of glory, as they clearly show by preserving the, trophies of their prowess, by their habit of excessive boasting, and even by the extreme care which they take of their per- sonal appearance and decorations ; for unless they regarded the opinion of their comrades, such habits would be senseless. They certainly feel shame at the breach of some of their lesser rules, and apparently remorse, as shewn by the case of the Australian who grew thin and could not rest from having delayed to murder some other woman> so as to propitiate his dead wife's spirit. Though I have not met with any other recorded case* it is scarcely credible that a savage, who will sacrifice his life rather than betray his tribe, or one who will deliver himself up as a prisoner rather than break his parole,6 would not feel remorse in his inmost soul, if he had failed in a duty, which he held sacred. "We may therefore conclude that primeval man, at a very remote period, was influenced by the praise and blame of his fellows. It is obvious, that the members of the same tribe would approve of conduct which appeared to them to be for the generai good, and would reprobate that which appeared evil To do good unto others-feto d6 unto others, as ye would they should do unto you-^is the ^foundation-stone of morality. It is, therefore, hardly possible to exaggerate; the importance during rude times • Mr. Wallace gives cases in of Natural Selection,* 1870, p, !>i* " CPWViputious to the Theory 354, K 2 1 32 The Descent of Man, Past L of the love of praise and the dread of blame. A man who was not impelled by any deep, instinctive feeling, to sacrifice his life for the good of others, yet was roused to such actions by a sense of glory, would by his example excite the same wish for glory in other men, and would strengthen by exercise the noble feeling of admiration. He might thus do far more good to his tribe than by begetting offspring with a tendency to inherit his own high character. With increased experience and reason, man perceives the more remote consequences of his actions, and the self-regarding virtues, such as temperance, chastity, &c, which during early times are, as we have before seen, utterly disregarded, come to be highly esteemed or even held sacred. I need not, however, repeat what I have said on this head in the fourth chapter. Ultimately our moral sense or conscience becomes a highly complex sentiment— originating in the social instincts, largely guided by the approbation of our fellow-men, ruled by reason, self-interest, and in later times by deep religious feelings, and confirmed by instruction and habit. It must not be forgotten that although a high standard of morality gives but a slight or no advantage to each individual man and his children over the other men of the same tribe, yet that an increase in the number of well-endowed men and an advancement in the standard of morality will certainly give an immense advantage to one tribe over another. A tribe including many members who, from possessing in a high degree the spirit of patriotism, fidelity, obedience, courage, and sympathy, were always ready to aid one another, and to sacrifice themselves for the common good, would be victorious over most other tribes ; and this would be natural selection. At all times throughout the world tribes have supplanted other tribes ; and as morality is one important 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 successful and has risen in the scale of civilisation. Many savages are in the same condition as when first discovered several centuries ago. As Mr. Bagehot has remarked, we are apt to look at progress as normal in human society ; but history refutes this. The ancients did not even entertain the idea, nor do the Oriental nations at the present day. According to another high authority, Sir Henry Maine,7 " the greatest part of mankind has never shewn a 7 'Ancient Law,' 1861, p. 22. nightly Review/ ipril 1, 1868, p. For Mr. Bagehot's remarks, < Fort 462. Chap. V. Civilised Nations. 133 u particle of desire that its civil institutions should be im- " proved." Progress seems to depend on many concurrent favourable conditions, far too complex to be followed out. But it has often been remarked, that a cool climate, from leading to industry and to the various arts, has been highly favourable thereto. The Esquimaux, pressed by hard necessity, have succeeded in many ingenious inventions, but their climate has been too severe for continued progress. Nomadic habits, whether over wide plains, or through the dense forests of the tropics, or along the shores of the sea, have in every case been highly detrimental. Whilst observing the barbarous inhabitants 0! Tierra del Fuego, it struck me that the possession of some property, a fixed abode, and the union of many families under a chief, were the indispensable requisites for civilisation. Such habits almost necessitate the cultivation of the ground ; and the first steps in cultivation would probably result, as I have else- where shewn,8 from some such accident as the seeds of a fruit- tree falling on a heap of refuse, and producing an unusually fine variety. The problem, however, of the first advance of savages towards civilisation is at present much too difficult to be solved. Natural Selection as affecting Civilised Nations. — I have hitherto only considered the advancement of man from a semi-human condition to that of the modern savage. But some remarks on the action of natural selection on civilised nations may be worth adding. This subject has been ably discussed by Mr. W. K. Greg,9 and previously by Mr. Wallace and Mr. Gaiton.10 Most of my remarks are taken from these three authors. With savages, the weak in body or mind are soon eliminated ; and those that survive commonly exhibit a vigorous state of health. We civilised men, on the other hand, do our utmost to check the process of elimination ; we build asylums for the imbecile, the maimed, and the sick ; we institute poor-laws ; and our medical 8 * The Variation of Animals and 1869, and by Mr. E. Ray Lankester Plants under Domestication/ vol. i, in his * Comparative Longevity/ p. 309. 1870, p. 128. Similar views ap- • 'Fraser's Magazine/ Sept. 1868, peared previously in the *Austra- p. 353. This article seems to have lasian/ July 13, 1867. I have struck many persons, and has given borrowed ideas from several of these rise to two remarkable essays and a writers. J-ejoinder in the * Spectator/ Oct. 19 For Mr. Wallace, see * Anthro- 3rd and 17th, 1868. It has also polog. Review/ as before cited. Mr. been discussed in the ' Q. Journal of Gaiton in * Macmillan's Magazine,' Science/ 1869, p. 152, and by Mr. Aug. 1865, p. 318 ; also his great Lawson Tait in the 4 Dublin Q, work, ' Hereditary Genius/ 1870. /onrnai of Medical Science/ Feb. 134 Tlie Descent of Man. PahtL men exert their utmost skill to save the life of every one to the last moment. There is reason to believe that vaccination has preserved thousands, who from a weak constitution would formerly have succumbed to small-pox. Thus the weak members of civilised societies propagate their kind. No one who has attended to the breeding of domestic animals will doubt that this must be highly injurious to the race of man. It is surprising how soon a want of care, or care wrongly directed, leads to the degeneration of a domestic race ; but excepting in the case of man himself, hardly any one is so ignorant as to allow his worst animals to breed. The aid which we feel impelled to give to the helpless is mainly an incidental result of the instinct of sympathy, which was originally acquired as part of the social instincts, but sub- sequently rendered, in the manner previously indicated, more tender and more widely diffused. Nor could we check our sympathy, even at the urging of hard reason, without deteriora- tion in the noblest part of our nature. The surgeon may harden himself whilst performing an operation, for he knows that he is acting for the good of his patient ; but if we were intentionally to neglect the weak and helpless, it could only be for a* con- tingent benefit, with an overwhelming present evil. We must therefore bear the undoubtedly bad effects of the weak surviving and propagating their kind; but there appears to be at least one check in steady action, namely that the weaker and inferior members of society do not marry so freely as the sound; and this check might be indefinitely increased by the weak in body or mind refraining from marriage, though this is more to be hoped for than expected. In every country in which a large standing army is kept up, the finest young men are taken by the conscription or are enlisted. They are thus exposed to early death during war, are often tempted into vice, and are prevented from marrying during the prime of life. On the other hand the shorter and feebler men, with poor constitutions, are left at home, and consequently have a much better chance of marrying and propagating their kind.11 Man accumulates property and bequeaths it to his children, so that the children of the rich have an advantage over the poor in the race for success, independently of bodily or mental su- periority. On the other hand, the children of parents who are short-lived, and are therefore on an average deficient in health and vigour, come into their property sooner than other children, 11 Prof. H. Fick (' Einfluss der on this head, and on other eucfl Naturwissenschaft auf das Recht,* porctc. June, 1872) has some good remarks Cb ap. Y. Civilised Nations. 1 3 $ and will be likely to marry earlier, and leave a larger number of offspring to inherit their inferior constitutions. But the in- heritance of property by itself is very far from an evil ; for without the accumulation of capital the arts cculd not progress; and it is chiefly through their power that the civilised races have extended, and are now everywhere extending their range, so as to take the place of the lower races. Nor does the moderate accumulation of wealth interfere with the process of selection. When a poor man becomes moderately rich,, his children enter trades or .professions in which there is struggle enough, so that the able in body and mind succeed best. The presence of a body of well-instructed men, who have not to labour for their daily bread, is important to a degree which cannot be over-estimated ; as all high intellectual work is carried on by them, and on such work, material progress of all kinds mainly depends, not to mention other and higher advantages. No doubt wealth when very great tends to convert men into useless drones, but their number is never large ; and some degree of elimination here occurs, for we daily see rich men, who happen to be fools or profligate, squandering away their wealth. Primogeniture with entailed estates is a more direct evil, though it may formerly have been a great advantage by the creation of a dominant class, and any government is better than none. Most eldest sons, though they may be weak in body or mind, marry, whilst the younger sons, however superior in these respects, do not so generally marry. Nor can worth- less eldest sons with entailed estates squander their wealth. But here, as elsewhere, the relations of civilised life are so complex that some compensatory checks intervene. The men who are rich through primogeniture are able to select genera- tion after generation the more beautiful and charming women ; and these must generally be healthy in body and active in mind. The evil consequences, such as they may be, of the continued preservation of the same line of descent, without any selection, are checked by men of rank always wishing to increase their wealth and power; and this they effect by marrying heiresses. But the daughters of parents who have produced single children, are themselves, as Mr. Oalton has shewn, apt to be sterile ; and thus noble families are continually cut off in the direct line, and their wealth flows into some side channel; but unfortunately this channel is not determined by superiority of any kind. Although civilisation thus checks in many ways the action of 12 * Hereditary Greaius ' 1870, pp. 132-140. 136 The Descent of Man. Part L natural selection, it apparently favours the better development of the body, by means of good food and the freedom from occa- sional hardships. This may be inferred from civilised men having been found, wherever compared, to be physically stronger than savages.13 They appear also to have equal powers of endurance, as has been proved in many adventurous ex- peditions. Even the great luxury of the rich can be but little detrimental ; for the expectation of life of our aristocracy, at all ages and of both sexes, is very little inferior to that of healthy English lives in the lower classes.14 We will now look to the intellectual faculties. If in eacli grade of society the members were divided into two equal bodies, the one including the intellectually superior and the other the inferior, there can be little doubt that the former would succeed best in all occupations, and rear a greater number of children. Even in the lowest walks of life, skill and ability must be of some advantage; though in many occupations, owing to the great division of labour, a very small one. Hence in civilised nations there will be some tendency to an increase both in the number and in the standard of the intellectually able. But I do not wish to assert that this tendency may not be more than counterbalanced in other ways, as by the multiplica- tion of the reckless and improvident ; but even to such as these, ability must be some advantage. It has often been objected to views like the foregoing, that the most eminent men who have ever lived have left no offspring to inherit their great intellect. Mr. Galton says,15 " I regret I am " unable to solve the simple question whether, and bow far, t{ men and women who are prodigies of genius are infertile. I '* have, however, shewn that men of eminence are by no means ' so." Great lawgivers, the founders of beneficent religions, <*reat philosophers and discoverers in science, aid the progress of mankind in a far higher degree by their works than by leaving a numerous progeny. In the case of corporeal structures, it is the selection of the slightly better-endowed and the elimination of the slightly less well-endowed individuals, and not the pre- servation of strongly-marked and rare anomalies, that leads to the advancement of a species.16 So it will be with the intellectual faculties, since the somewhat abler men in each grade of society 13 Quatrefages, * Revue des Cours 1870, p. 115. Scientifiques/ 1867-68, p. 659. >* * Hereditary Genius/ 1870, p. 14 See the fifth and sixth columns, 330. compiled from good authorities, in " ' Origin of Species ' (fifth eii« the table given in Mr. E. R. Lan- tion, 1869), p. 104. kester's * Comparative Longevity Chap. V. Civilised Nations. 1 37 succeed rather better than the less able, and consequently increase in number, if not otherwise prevented. When in any nation the standard of intellect and the number of intel- lectual men have increased, we may expect from the law of the deviation from an average, that prodigies of genius will, as shewn by Mr. Galton, appear 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 civilised nations. Malefactors are executed, or imprisoned for long periods, so that they cannot freely transmit their bad qualities. Melancholic and insane persons are confined, or commit suicide. Violent and quarrelsome men often come to a bloody end. The restless who will not follow any steady occupation — and this relic of barbarism is a great check to civilisation17 — emigrate to newly-settled countries, where they prove useful pioneers. In- temperance is so highly destructive, that the expectation of life of the intemperate, at the age of thirty for instance, is only 13*8 years ; whilst for the rural labourers of England at the same age it is 40*59 years.18 Profligate women bear few children, and profligate men rarely marry ; both suffer from disease. In the breeding of domestic animals, the elimination of those individuals* though few in number, which are in any marked manner inferior, is by no means an unimportant element towards success. This especially holds good with injurious characters which tend tc 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 recognised in the common expression that such men are the black sheep of the family. With civilised nations, as far as an advanced standard of morality, and an increased number of fairly good men are con- cerned, natural selection apparently effects but little ; though the fundamental social instincts were originally thus gained. But I have already said enough, whilst treating of the lower races, on the causes which lead to the advance of morality, namely, the approbation of our fellow-men — the strengthening 17 * Hereditary Genius,' 1870, p. Neison's * Vital Statistics.' In re- 34-7. gard to profligacy, see Dr. Fair, lf E. Ray Lankester, * Compara- * Influence of Marriage on Mor* tive Longevity/ 1570, p. 115. The tality/ * Nat. Assoc, for the Promo* table of the intemperate is from tion of Social Science/ IS'jS. 138 The Descent of Man. i>art I. 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 civilised countries to an increase in the number of men of a superior class has been strongly insisted un by Mr. Greg and Mr. Galton,19 namely, the fact that the very poor and reckless, who are often degraded by vice, almost invari- ably marry early, whilst the careful and frugal, who are generally ccherwise virtuous, marry late in life, so that they may be able co support themselves and their children in comfort. Those who marry early produce within a given period not only a greater number of generations, but, as shewn by Dr. Duncan,20 they pro- duce many more children. The children, moreover, that are born by mothers during the prime of life are heavier and larger, and therefore probably more vigorous, than those born at other periods. Thus the reckless, degraded, and often vicious members of society, tend to increase at a quicker rate than the provident and generally virtuous members. Or as Mr. Greg puts the case : " The careless, squalid, unaspiring Irishman multiplies like "rabbits: the frugal, foreseeing, self-respecting, ambitious Scot, "stern in his morality, spiritual in his faith, sagacious and dis- " ciplined in his intelligence, passes his best years in struggle "and in celibacy, marries late, and leaves few behind him. " Given a land originally peopled by a thousand Saxons and a * thousand Celts — and in a dozen generations five-sixths of the ^population would be Celts, but five-sixths of the property, of " the power, of the intellect, would belong to the one-sixth of " Saxons that remained. In the eternal ' struggle for existence/ " it would be the inferior and less favoured race that had pre- " vailed — and prevailed by virtue not of its good qualities but of -its faults." There are, however, some checks to this downward tendency. We have seen that the 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,21 that at all 19 ' Fraser*s Magazine,* Sept. title of ' Fecundity, Fertility, and 1868, p. 353. 'Macmillan's Maga- Sterility,* 1871. See, also, Mr zine, Aug. 1865, p. 318. The Rev. Galton, * Hereditary Genius/ pp. F. W. Farrar (' Fraser*s Mag.* Aug. 35L ^357, for observations to the 1870, p. 264) takes a different view, above effect. 96 « On the Laws of the Fertility 21 * Tenth Annual Report 01 of Women,' in * Transact. Royal Births, Deaths, &c, id Scotland, Soc.' Edinburgh, vol. xxiv. p. 287; 1867, p, xxix. »ow published separately under the Chap. V. Civilised Nations. 1 39 ages the death-rate is higher in towns than in rural districts, '' &nd during the first five years of life the town death-rate ia "almost exactly double that of the rural districts." As these re- turns include both the rich and the poor, no doubt more than twice the number of births would be requisite to keep up the number of the very poor inhabitants in the towns, relatively to those in the country. With women, marriage at too early an age is highly injurious ; for it has been found in France that, " twice as many wives under twenty die in the year, as died out " of the same number of the unmarried." The mortality, also, of husbands under twenty is "excessively high,"22 but what the cause of this may be, seems doubtful. Lastly, if the men who prudently delay marrying until they can bring up their families in comfort, were to select, as they often do, women in the prime of life, the rate of increase in the better class would be only slightly lessened. It was established from an enormous body of statistics, taken during 1853, that the unmarried men throughout France, between the ages of twenty and eighty, die in a much larger proportion than the married : for instance, out of every 1000 unmarried men, between the ages of twenty and thirty, 11*3 annually died, whilst of the married only 65 died.23 A similar law was proved to hold good, during the years 1863 and 1864, with the entire population above the age of twenty in Scotland : for instance, out of every 1000 unmarried men, between the ages of twenty and thirty, 14*97 annually died, Whilst of the married only 7*24 died, that is less than half.24 Dr. Stark remarks on this, " Bachelorhood is more destructive to life than the most " unwholesome trades, or than residence in an unwholesome "house or district where there has never been the most distant "attempt at sanitary improvement." He considers that the lessened mortality is the direct result of "marriage, and the "more regular domestic habits which attend that state." He admits, however, that the intemperate, profligate, and criminal classes, whose duration of life is low, do not commonly marry ; and it must likewise be admitted that men with a weak constitu- ** These quotations are taken from the same striking paper, from our highest authority on such 24 I have taken the mean of the questions, namely, Dr. Farr, in his quinquennial means, given in 'The paper <0n the Influence of Mar- Tenth Annual Report of Births, riage on the Mortality of the French Deaths, &c, in Scotland/ 1867. People/ read before the Nat. Assoc. The quotation from Dr. Stark is for the Promotion cf Social Science* copied from an article in the * Daily 1858. , News/ Oct. 17th, Ig68, which Dr, 28 Dr. Farr, ibid. The quota- Farr considers very carefilly wriV iions given below are extracted ten. 140 Tlie Descent of Man. Part I, tion, ill health, or any great infirmity in body or mind, will often not wish to marry, or will be rejected. Dr. Stark seems to have come to the conclusion that marriage in itself is a main cause of prolonged life, from finding that aged married men still have a considerable advantage in this respect over the unmarried of the same advanced age ; but every one must have known instances of men, who with weak health during youth did not marry, and yet have survived to old age, though remaining weak, and there- fore always with a lessened chance of life or of marrying. There is another remarkable circumstance which seems to support Dr. Stark's conclusion, namely, that widows and widowers in France suffer in comparison with the married a very heavy rate of mor- tality ; but Dr. Farr attributes this to the poverty and evil habits consequent on the disruption of the family, and to grief. On the whole we may conclude with Dr. Farr that the lesser mortality of married than of unmarried men, which seems to be a general law, "is mainly due to the constant elimination of imperfect *' types, and to the skilful selection of the finest individuals out " of each successive generation ;" the selection relating only to the marriage state, and acting on all corporeal, intellectual, and moral qualities.25 We may, therefore, infer that sound and good men who out of prudence remain for a time unmarried, do not suffer a high rate of mortality. If the various checks specified in the two last paragraphs, and perhaps others as yet unknown, do not prevent the reckless, the vicious and otherwise inferior members of society from increas- ing at a quicker rate than the better class of men, the nation will retrograde, as has too often occurred in the history of the world. We must remember that progress is no invariable rule. It is yery difficult to say why one civilised nation rises, becomes more powerful, and spreads more widely, than another; or why the same nation progresses more quickly at one time than at another. We can only say that it depends on an increase in the actual number of the population, on the number of the men endowed with high intellectual and moral faculties, as well as on their standard of excellence. Corporeal structure appears to have little influence, except so far as vigour of body leads to vigour of mind. It has been urged by several writers that as high intellectual powers are advantageous to a nation, the old Greeks, who stood some grades higher in intellect than any race that has ever •5 Dr. Duncan remarks (' Fecund- " from the unmarried side to th< ity, Fertility/ &c, 1871, p. 334) on " married, leaving the unmarried this subject; "At every age the "columns crowded with the sickly ,w healthy and beautiful go over " and unfortunate/' Cha? V. Civilised Nations. 141 existed,26 ought, if the power of natural selection were real, to have risen still higher in the scale, increased in number, and stocked the whole of Europe. Here we have the tacit assump- tion, so often made with respect to corporeal structures, that there is some innate tendency towards continued development in mind and body. But development of all kinds depends on many concurrent favourable circumstances. Natural selection acts only tentatively. Individuals and races may have acquired cer- tain indisputable advantages, and yet have perished from failing in other characters. The Greeks may have retrograded from a want of coherence between the many small states, from the small size of their whole country, from the practice of slavery, or from extreme sensuality ; for they did not succumb until ** they were " enervated and corrupt to the very core."27 The western nations of Europe, who now so immeasurably surpass their former savage progenitors, and stand at the summit of civilisation, owe little or none of their superiority to direct inheritance from the old Greeks, though they owe much to the written works of that wonderful people. Who can positively say why the Spanish nation, so dominant at one time, has been distanced in the race. The awakening of the nations of Europe from the dark ages is a still more perplex- ing problem. At that early period, as Mr. Galton has remarked, almost all the men of a gentle nature, those given to meditation or culture of the mind, had no refuge except in the bosom of a Church which demanded celibacy;28 and this could hardly fail to have had a deteriorating influence on each successive generation. During this same period the Holy Inquisition selected with extreme care the freest and boldest men in order to burn or imprison them. In Spain alone some of the best men — those who doubted and questioned, and without doubting there can be no progress — were eliminated during three cen- turies at the rate of a thousand a year. The evil which the Catholic Church has thus effected is incalculable, though no dczbt counterbalanced to a certain, perhaps to a large, extent in other ways ; nevertheless, Europe has progressed at an un- paralleled rate. *• See the ingenious and original 257) advances arguments on the argument on this subject by Mr. other side. Sir C. Lyell had already Galton, * Hereditary Genius,' pp. (' Principles of Geology,' vol. u. 340-342. 1868, p. 489) in a striking passage 27 Mr. Greg, * Eraser's Magazine,' called attention to the evil influence Sept. 1868, p. 357. of the Holy Inquisition in having, *• ' Hereditary Genius,* 1870, pp. through selection, lowered the gene- 357-359. The Rev. F. W. Farrar ral standard of intelligence in £u- ('Fraser's Mag.,' Aug. 1870, p. rope. 142 Tlie Descent of Man. Paet I. The remarkable success of the English as colonists, compared toother European nations, has been ascribed to their "daring " and persistent energy ; " a result which is well illustrated by comparing the progress of the Canadians of English and French extraction ; 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 ; for the more ener- getic, restless, and courageous men from all parts of Europe have emigrated during the last ten or twelve generations to that great country, and have there succeeded best.29 Looking to the distant future, I do not think that the Eev. Mr. Zincke takes an exaggerated view when he says Is0 " All other series of events — " as that which resulted in the culture of mind in Greece, and "that which resulted in the empire of Eome— 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 civilisation, we can at least see that a nation which produced during a lengthened period the greatest number of highly intellectual, energetic, brave, patriotic, and benevolent men, would generally prevail over less favoured nations. Natural selection follows from the struggle for existence ; and this from a rapid rate of increase. It is impossible not to regret bitterly, but whether wisely is another question, the rate at which man tends to increase ; for this leads in barbarous tribes to infanticide and many other evils, and in civilised nations to abject poverty, celibacy, and to the late marriages of the prudent. But as man suffers from the same physical evils as the lower animals, he has no right to expect an immunity from the evils consequent on the struggle for existence. Had he not been sub- jected during primeval times to natural selection, assuredly he would never have attained to his present rank. Since we see in many parts of the world enormous areas of the most fertile land capable of supporting numerous happy homes, but peopled only by a few wandering savages, it might be argued that the struggle for existence had not been sufficiently severe to force man up- wards to his highest standard. Judging from all that we know of man and the lower animals, there has always been sufficient variability in their intellectual and moral faculties, for a steady advance through natural selection. No doubt such advance ** Mr. Gaiton, < Macmillan's and National Life/ Dec. 1869, p. 184. Magazine,' August, 1865, p. 325. 30 'Last. Winter in the United See also, ' Nature,* « On Darwinism States,' 1868, p. 29. Ohap.T. Civilised Nations. 143 demands many favourable concurrent circumstances; but it may well be doubted whether the most favourable would have sufficed, had not the rate of increase been rapid, and the consequent struggle for existence extremely severe. It even appears from what we see, for instance, in parts of S. America, that a people which may be called civilised, such as the Spanish settlers, is liable to become indolent and to retrograde, when the con- ditions of life are very easy. With highly civilised nations con- tinued progress depends in a subordinate degree on natural selection ; for such nations do not supplant and exterminate one another as do savage tribes. Nevertheless the more intelligent members within the same community will succeed better in the long run than the inferior, and leave a more numerous progeny, and this is a form of natural selection. The more efficient causes of progress seem to consist of a good education during youth whilst the brain is impressible, and of a high standard of excellence, inculcated by the ablest and best men, embodied in the laws, customs and traditions of the nation, and enforced by public opinion. It should, however, be borne in mind, that the enforcement of public opinion depends on our appreciation of the approbation and disapprobation of others ; and this apprecia- tion is founded on our sympathy, which it can hardly be doubted was originally developed through natural selection as one of the most important elements of the social instincts.81 On the evidence that all civilised nations were once barbarous.— The present subject has been treated in so full and admirable a manner by Sir J. Lubbock,32 Mr. Tylor, Mr. M'JLennan, and others, that I need here give only the briefest summary of their results. The arguments recently advanced by the Duke of Argyll33 and formerly by Archbishop Whately, in favour of the belief that man came into the world as a civilised being, and that all savages have since undergone degradation, seem to me weak in comparison with those advanced on the other side. Many nations, no doubt, have fallen away in civilisation, and some may have lapsed into utter barbarism, though on this latter head I have met with no evidence. The Fuegians were probably compelled by other conquering hordes to settle in their inhospitable country, and they may have become in consequence somewhat more degraded; but it would be difficult to prove **' I am much indebted to Mr. 8a ' On the Origin of Civilisation/ John Morley for some good criti- *Proc. Ethnological Soc.* Nov, 26 eisms on this subject: see, also, 1867. Broca, *Les Selections/ * Revue d'An- ■» ' Primeval Man/ 1869. fcbropologie/ 1872. 144 The Descent of Man. Pabt L that they have fallen much below the Botocudos, who inhabit fche finest parts of Brazil. The evidence that all civilised nations are the descendants of barbarians, consists, on the one side, of clear traces of theii former low condition in still-existing customs, beliefs, language, &c. ; and on the other side, of proofs that savages are inde- pendently able to raise themselves a few steps in the scale of civilisation, and have actually thus risen. The evidence on the first head is extremely curious, but cannot be here given : I refer to such cases as that of the art of enumeration, which, as Mr. Tylor clearly shews by reference to the words still used in some places, originated in counting the fingers, first of one hand and then of the other, and lastly of the toes. We have traces of this in our own decimal system, and in the Roman numerals, where, after the V., which is supposed to be an abbreviated picture of a human hand, we pass on to VI., &c, when the other hand no doubt was used. So again, " when we speak of three-score and " ten, we are counting by the vigesimal system, each score thus " ideally made, standing for 20 — for ' one man ' as a Mexican or " Carib would put it."34 According to a large and increasing school of philologists, every language bears the marks of its slow and gradual evolution. So it is with the art of writing, for letters are rudiments of pictorial representations. It is hardly possible to read Mr. M'Lennan's work85 and not admit that almost all civilised nations still retain traces of such rude habits as the forcible capture of wives. What ancient nation, as the same author asks, can be named that was originally mono- gamous? The primitive idea of justice, as shewn by the law of battle and other customs of which vestiges still remain, was likewise most rude. Many existing superstitions are the remnants of former false religious beliefs. The highest form of religion — the grand idea of God hating sin and loving right- eousness— was unknown during primeval times. Turning to the other kind of evidence : Sir J. Lubbock has shewn that some savages have recently improved a little in some of their simpler arts. From the extremely curious account which he gives of the weapons, tools, and arts, in use ** 'Royal Institution of Great 'A Conjectural Solution of the Britain,' March 15, 1867. Also, Origin of the Class, System of * Researches into the Early History Relationship/ in ' Proc. American of Mankind,' 1865. Acad, of Sciences/ vol. vii. Feb. •* 'Primitive Marriage/ 1865. 1868. Prof. Schaaffhausen ('An- 3ee, likewise, an excellent article, thropolog. Review/ Oct. 1869, p. evidently by the same author, in 373) remarks on "the vestiges of the ' North British Review/ July, " human sacrifices found both io 1869. Also, Mr. L. H. Morgan, " Homer and the Old Testament." Chap. V, Nations. 145 amongst savages in various parts of the world, it cannot bo doubted that these have nearly all been independent discoveries, excepting perhaps the art of making fire.36 The Australian boomerang is a good instance of one such independent discovery. The Tahitians when first visited had advanced in many respects beyond the inhabitants of most of the other Polynesian islands. There are no just grounds for the belief that the high culture of the native Peruvians and Mexicans was derived from abroad ;" many native plants were there cultivated, and a few native animals domesticated. We should bear in mind that, judging from the small influence of most missionaries, a wandering crew from some senii-civilised land, if washed to the shores of America, would not 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, wo find, to use Sir J. Lubbock's well-known terms, a paleolithic and neolithic period ; and no one will pretend that the art of grinding rough flint tools was a borrowed one. In all parts of Europe, as far east as Greece, in Palestine, India, Japan, New Zealand, and Africa, including Egypt, flint tools have been discovered in abundance; and of their use the existing in- habitants retain no tradition. There is also indirect evidence of their former use by the Chinese and ancient Jews. Hence there can hardly be a doubt that the inhabitants of these countries, which include nearly the whole civilised world, were once in a barbarous condition. To believe that man was abori- ginally civilised and then suffered utter degradation in so many regions, is to take a pitiably low view of human nature. It is apparently a truer and more cheerful view that progress nas 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. 8a Sir J. Lubbock, « Prehistoric edit., 1870. Times/ 2nd edit. 1869, chap. xv. » Dr. F. Miiller has made som* and xvi. et passim. See also the good remarks to this eflect in th« excellent 9th c\apter in Trior's * Reise der Novara : Anthropo^og * Early History »f Mankind,* 2nd Theil/ Abthei1 iii. 1868 s. 127. 145 The Descent of Man. r Afct 1 CHAPTER VL On the Affinities and Genealogy of Man. Petition of man in the animal series — The natural system genealogical—* Adaptive characters of slight value — Various small points of rescm- " blance between man and the Quadrumana — Rank of man in the natural system — Birthplace and antiquity of man — Absence of fossil connecting- links* — Lower stages in the genealogy of man, as inferred, firstly from his affinities and secondly from his structure — Early androgynous con- dition of the Vertebrata — Conclusion. Even if it be granted that the difference between man and his nearest allies is as great in corporeal structure as some natu- ralists maintain, and although we must grant that the differ- ence between them is immense in mental power, yet the facts given in the earlier chapters appear to declare, in the plainest manner, that man is descended from some lower form, notwith- standing that connecting-links have not hitherto been dis- covered. Man is liable to numerous, slight, and diversified variations, which are induced by the same general causes, are governed and transmitted in accordance with the same general laws, as in the lower animals. Man has multiplied so rapidly, that he has necessarily been exposed to struggle for existence, and con- sequently to natural selection. He has given rise to many races, some of which differ so much from each other, that they have often been ranked by naturalists as distinct species. His body is constructed on the same homological plan as that of other mammals. 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 re-appearance in him, which we have reason to believe were possessed by his early progenitors. If the origin of man had been wholly different from that of all other animals, these various appearances would be mere empty deceptions ; but such an admission is incredible. These appear- ances, on the other hand, are intelligible, at least to a large extent, if man is the co-descendant with other mammals of some unknown and lower form. Some naturalists, from being deeply impressed with tho mental and spiritual powers of man, have divided the whole areradc world into three kingdoms, the Human, the Animal, Chap. VI. Affinities and Genealogy. *47 and the Vegetable, thus giving to man a separate kingdom.1 Spiritual powers cannot be compared or classed by the natu- ralist : but he may endeavour to shew, as I have done, that the mental faculties of man and the lower animals do not differ in kind, although immensely in degree. A difference in degree, . however great, does not justify us in placing man in a distinct kingdom, as will perhaps be best illustrated by comparing the mental 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 than, though of a somewhat different kind from, that between man and the highest mammal. The female coccus, whilst young, attaches itself by its proboscis to a plant ; sucks the sap, but never moves again; is fertilised and lays eggs; and this is its whole history. On the other hand, to describe the habits and mental powers of worker-ants, would require, as Pierre Huber has shewn, a large volume ; I may, however, briefly specify a few points. Ants certainly communicate information to each other, and several unite for the same work, or for games of play. They recognise their fellow-ants after months of absence, and feel sympathy for each other. They build great edifices, keep them clean, close the doors in the evening, and post sentries. They make roads as well as tunnels under rivers, and temporary bridges over them, by clinging together. They collect food for the community, and when an object, too large for entrance, is brought to the nest, they enlarge the door, and afterwards build it up again. They store up seeds, of which they prevent the germination, and which, if damp, are brought up to the surface to dry. They keep aphides and other insects as milch-cows. They go out to battle in regular bands, and freely sacrifice their lives for the common weal. They emigrate ac- cording to a preconcerted plan. They capture slaves. They move the eggs of their aphides, as well as their own eggs and cocoons, into warm parts of the nest, in order that they may be quickly hatched ; and endless similar facts could be given.3 On the whole, the difference in mental power between an ant and a coccus is immense ; yet no one has ever dreamed of plying these insects in distinct classes, much less in distinct kingdoms. No 1 Isidore Geoffroy St.-Hilaire gives of ants are given by Mr. Belt, in a detailed account of the position in his * Naturalist, in Nicaragua/ assigned to man by various natural- 1874. See also Mr. Moggridge's ists in their classifications: as Professor Schaafifhausen has remarked,18 will no doubt be exterminated. The break between man and his nearest allies will then be wider, for it will intervene between man in a more civilised state, as we may hope, even than the Caucasian, and some ape as low as a baboon, instead of as now between the negro or Australian and the gorilla. -• Anthropological Review,' April, 1867, p. 236. ChaaVI. Affinities and Genealogy. i$7 With respect to the absence of fossil remains, serving to connect man with his ape-like progenitors, no one will lay much stress on this fact who reads Sir C. LyelPs discussion,1* where he shews that in all the vertebrate classes the discovery of fossil remains has been a very slow and fortuitous process. Nor should it be forgotten that those regions which are the most likely to afford remains connecting man with some extinct ape- like creature, have not as yet been searched by geologists. Lovjer Stages in the Genealogy of Man. — "We have seen that man appears to have diverged from the Catarhine or Old World division of the Simiadss, after these had diverged from the New World division. We will now endeavour to follow the remote traces of his genealogy, trusting principally to the mutual affinities between the various classes and orders, with some slight reference to the periods, as far as ascertained, of their successive appearance on the earth. The Lemuridae stand below and near to the Simiadae, and constitute a very distinct family of the Primates, or, according to Hackel and others, a distinct Order. This group is diversified and broken to an extraordinary degree, and includes many aberrant forms. It has, therefore, probably suffered much extinction. Most of the remnants survive on islands, such as Madagascar and the Malayan archipelago, where they have not been exposed to so severe a competition as they would have been on well-stocked continents. This group likewise presents many gradations, leading, as Huxley remarks,20 " insensibly from the crown and " summit of the animal creation down to creatures from which " there is but a step, as it seems, to the lowest, smallest, and " least intelligent of the placental mammalia." From these various considerations it is probable that the Simiada3 were originally developed from the progenitors of the existing Lemuridae ; and these in their turn from forms standing very low in the mammalian series. The Marsupials stand in many important characters below the placental mammals. They appeared at an earlier geological period, and their range was formerly much more extensive than at present. Hence the Placentata are generally supposed to have been derived from the Implacentata or Marsupials; not, however, from forms closely resembling the existing Mar- supials, but from their early progenitors. The Monotremata are plainly allied to the Marsupials, forming a third and still lower w * Elements of Geology/ 1865, 20 ' Man's Place in ft&lnxt, jv pp. 583-585, * Antiquity of Man.' 105. l«33* p. H5. 158 The Descent of Man. Pakt I 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, representatives of which have been preserved in Australia through some favourable concurrence of circum- stances. The Monotremata are eminently interesting, as leading m several important points of structure towards the class of reptiles. In attempting to trace the genealogy of the Mammalia, and therefore of man, lower down in the series, we become involved in greater and greater obscurity; but as a most capable judge, Mr. Parker, has remarked, we have good reason to believe, that no true bird or reptile intervenes in the direct line of descent. He who wishes to see what ingenuity and knowledge can effect, may consult Prof. Hackers works.21 I will content myself with a few general remarks. Every evolutionist will admit that the five great vertebrate classes, namely, mammals, birds, reptiles, amphibians, and fishes, are descended from some one prototype ; for they have much in common, especially during their embryonic state. As the class of fishes is the most lowly organised, and appeared before the others, we may conclude that all the members of the vertebrate kingdom are derived from some fish- like animal. The belief that animals so distinct as a monkey, an elephant, a humming-bird, a snake, a frog, and a fish, &c, could all have sprung from the same parents, will appear monstrous to those who have not attended to the recent progress of natural history. For this belief implies the former existence of links binding closely together all these forms, now so utterly unlike. Nevertheless, it is certain that groups of animals have existed, or do now exist, which serve to connect several of the great vertebrate classes more or less closely. We have seen that the Ornithorhynchus graduates towards reptiles ; and Prof. Huxley has discovered, and is confirmed by Mr. Cope and others, that the Dinosaurians are in many important characters intermediate between certain reptiles and certain birds — the birds referred to being the ostrich-tribe (itself evidently a widely-diffused remnant of a larger group) and the Archeopteryx, that strange Secondary bird, with a long lizard-like tail. Again, according to 21 Elaborate tables are given in the phylum or lines of descent of his * Generelle Morphologie ' (B. ii. the Vertebrata to be admirably dis- 5. cliii. and s. 425); and with more cussed by Hackel, although he differs especial reference to man in his on some points. He expresses, 'Naturliche Schopfungsgeschichte/ also, his high estimate of the 1868. Prof. Huxley, in reviewing general tenor and spirit of th« this latter work ('The Academy/ whole work. 1868, p. 42) says, that he considers n Palaeontology/ I860, p. 199, Chap. VI. Affinities and Genealogy, 159 Prof. Owen,22 the Ichthyosaurians— great sea-lizards furnished with paddles— present many affinities with fishes, or rather, according to Huxley, with amphibians; a class which, including in its highest division frogs and toads, is plainly allied to tho Ganoid fishes. These latter fishes swarmed during the earlier geological periods, and were constructed on what is called a generalised type, that is, they presented diversified affinities with other groups of organisms. The Lepidosiren is also so closely allied to amphibians and fishes, that naturalists long disputed in which of these two classes to rank it; it, and also some few Ganoid fishes, have been preserved from utter extinction by inhabiting rivers, which are harbours of refuge, and are related to the great waters of the ocean in the same way that islands are to continents. Lastly, one single member of the immense and diversified class of fishes, namely, the lancelet or amphioxus, is so different from all other fishes, that Hackel maintains that it ought to form a distinct class in the vertebrate kingdom. This fish is remarkable for its negative characters ; it can hardly be said to possess a brain, vertebral column, or heart, &c. ; so that it was classed by the older naturalists amongst the worms. Many years ago Prof. Goodsir perceived that the lancelet presented some affinities with the Ascidians, which are invertebrate, hermaphrodite, marine creatures permanently attached to a support. They hardly appear like animals, and consist of a simple, tough, leathery sack, with two small projecting orifices. They belong to the Moliuscoida of Huxley — a lower division of the great kingdom of the Mollusca; but they have recently been placed by some naturalists amongst the Vermes or worms. Their larvae some- what resemble tadpoles in shape,23 and have the power of swimming freely about. M.Kovalevsky24 has lately observed that the larvaa of Ascidians are related to the Vertebrata, in their manner of development, in the relative position of the nervous system, and in possessing a structure closely like the chorda dorsalis of vertebrate animals; and in this he has been since 2S At the Falkland Islands I had under a simple microscope, plainly the satisfaction of seeing, in April divided by transverse opaque parti* 1833, and therefore some years be- tions, which I presume represent fore any other naturalist, the loco- the great cells figured by Kovalev- raotive larva; of a compound Asci- sky. At aa early stage of develop- dian, closely allied to Synoicum, ment the tail was closely coil»£ but apparently generically distinct round th« head of the larva, from it. The tail was about five 2* ■* Memoires de l'Acad. dei times as long as the oblong head, Sciences de St. Petersbourg/ torn: x and terminated in a very fine fila- No. 15, 1866. iHifnt. It was, as sketched by me r DO The Descent of Man. Far? L confirmed i.\>7 Prof. Kupifer. M. Kovalevsky writes to me from Naples, that he has now carried these observations yet further , and should his results be well established, the whole will form a discovery of the very greatest value. Thus, if we may rely on embryology, ever the safest guide in classification, it seems that we have at last gained a clue to the source whence the Vertebrata were derived.23 We should then be justified in believing that at an extremely remote period a group of animals existed, resembling in many respects the larva) of our present Ascidians, which diverged into two great branches— the one retrograding in development and producing the present class of Ascidians,- the other rising to the crown and summit of the animal kingdom by giving birth to the Vertebrata. We have thus far endeavoured rudely to trace the genealogy of the Vertebrata 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 the structure of our early progenitors, during successive periods, but not in due order of time. This can bo effected by means of the rudiments which man still retains, by the characters which occasionally make their appearance in him through reversion, and by the aid of the principles of morphology and embryology. The various facts, to which I shall here allude, hayjeJbeen given in the previous chapters. ^ The early progenitors of man must have been once covered with hair, both sexes having beards ; their ears were probably pointed, and capable of moveruent ; and their bodies were pro- vided with & tail, having the proper muscles. Their limbs and bodies were also acted on by many muscles which now only occasionally reappear, but are normally present in the Quadru- mana. At this or some earlier period, the great artery and nerve of the humerus ran through a supra-condyloid foramen. The intestine gave forth a much larger diverticulum or caecum than that now existing. The foot was then prehensile, judging from the condition of the great toe in the foetus ; and our progenitors, no doubt, were arboreal in their habits, and frequented some warm, forest-clad land. The males had great canine teeth, which 85 But I am bound to add that " peut produire la disposition fonda- soine competent judges dispute this " mentale du type vert^bre" (rex- conclusion ; for instance, M. Giard, " istence d'une corde dorsale) chez in a series of papers in the* Archives " un inverters' par la seule con- de Zoologie Experi mentale,' for 1872. " dition vitale de l'adaptation, Nevertheless, this naturalist re- " et cette simple possibility du marks, p. 281, •* L'organisation &2 la " passage supprime Tabiinc ectre " larve ascidienne en dehors de " les deux sous-regnes, encore bien " toute hypotheseet detoutetheorie, " qu'en ignore par oil le passage u oous inoctrc coaimfiit la nature " u'est fait er r4?M%6" Chap.Vj. Affinities and Genealogy. 161 Bcrved them as formidable weapons. At a much earlier period the uterus was double; the excreta were voided through a cloaca; and the eye was protected by a third eyelid or nictitating mem- brane. At a still earlier period the progenitors of man must have been aquatic in their habits; for morphology plainly tells us that our lungs consist of a modified swim-bladder, which once served as a float. The clefts on the neck in the embryo of man show where the branchiae once existed. In the lunar or weekly re- current periods of some of our functions we apparently still retain traces of our primordial birthplace, a shore washed by the tides. At about this same early period the true kidneys were replaced by the corpora wolffiana. The heart existed as a simple pulsating vessel; and the chorda dorsalis took the place of a vertebral column. These early ancestors of man, thus seen in the dim recesses of time, must have been as simply, or even still more simply organised than the lancelet or amphioxus. There is one other point deserving a fuller notice. It has long been known that in the vertebrate kingdom one sex bear? rudiments of various accessory parts, appertaining to the re- productive system, which properly belong to the opposite sex ; and it has now been ascertained that at a very early embryonic period both sexes possess true male and female glands. Hence some remote progenitor of the whole vertebrate kingdom appears to have been hermaphrodite or androgynous.26 But here we encounter a singular difficulty. In the mammalian class the males possess rudiments of a uterus with the adjacent passage, in their vesiculse prostaticsB; they bear also rudiments of mammaB, and some male Marsupials have traces of a marsupial sack.27 Other analogous facts could be added. Are we, then, to suppose that some extremely ancient mammal continued andro- gynous, after it had acquired the chief distinctions of its class, and therefore after ii had diverged from the lower classes of the vertebrate kingdom ? This seems very improbable, for we have to look to fishes, the lowest of all the classes, to find any stil! existent androgynous forms.28 That various accessory parts, 28 This is the conclusion of Prof. " brata are, in their early condition, Gegenbaur, one of the highest au- " hermaphrodite." Similar views thoiities in comparative anatomy; have lomr been held by some authors, see ' Grundziige der vergleieh. Anat.' though until recently without a 1870, s. 876. The result has been firm basis. arrived at chiefly from the study of 2r The male Thylacinus offers the the Amphibia; but it appears frcm best instance. Owen, * Anatomy of the researches of Waldeyer (as Vertebrates,' vol. iii. p. 771. quoted in * Journal of Anat. and 28 Hermaphroditism has been ob- PKys/ 1869, p. 161), that the sexual served in several species of Seiranus, prg--"M of even "the higher verte- as well a> in some other fishes, 1 62 TJie Descent of Man. Part L proper to each sex, are found in a rudimentary condition in the opposite sex, may be explained by such organs having been gradually acquired by the one sex, said then transmitted in a more or less imperfect state to the other. When we treat of sexual selection, we shall meet with innumerable instances of this form of transmission, — as in the case of the spurs, plumes, and brilliant colours, acquired for battle or ornament by male birds, and inherited by the females in an imperfect or rudimentary condition. The possession by male mammals of functionally imperfect mammary organs is, in some respects, especially curious. Tho Monotremata have the proper milk-secreting glands with orifices, but no nipples ; and as these" animals stand at the very base of the mammalian series, it is probable that the progenitors of the class also had milk-secreting glands, but no nipples. This conclusion is supported by what is known of their manner of development ; for Professor Turner informs me, on the authority of Kolliker and Langer, that in the embryo the mammary glands can be distinctly traced before the nipples are in the least visible; and the development of successive parts in the indi- vidual generally represents and accords with the development of successive beings in the same line of descent. The Marsupials differ from the Monotremata by possessing nipples; so that probably these organs were first acquired by the Marsupials, after they had diverged from, and risen above, the Monotremata, and were then transmitted to the placental mammals.29 No one will suppose that the Marsupials still remained androgynous, after they had approximately acquired their present structure. How then are we to account for male mammals possessing mammae ? It is possible that they were first developed in the females and then transferred to the males ; but from what follows this is hardly probable. where it is either normal and sym- delle Scienze,' Bologna, Dec. 28, metrical, or abnormal and uni- 1871) that eels are androgynous, lateral. Dr. Zouteveen has given 29 Prof. Gegenbaur has shewn me references on this subject, more (' Jenaische Zeitschrift,' Bd. vii. p. especially to a paper by Prof. Hal- 212) that two distinct types of bertsma, in the 'Transact, of the nipples prevail throughout the Dutch Acad, of Sciences,' vol. xvi. several mammalian orders, but Dr. Gtinther doubts the fact, but that it is quite intelligible how both it has now been recorded by too could have been derived from the many good observers to be any nipples of the Marsupials, and the longer disputed. Dr. M. Lessona latter from those of the Monctre- writes to me, that he has veri- mata. See, also, a memoir &y Dr fied the observations made by Max Huss, on the mammary gkada, Carolini on Serranus. Prof. Erco- ibid. B. viii. p. 176. Uni has recently shewn (*Accad. Chap. YL Affinities and Genealogy. 1 63 It may be suggested, as another view, that long after the progenitors of the whole mammalian class had ceased to be androgynous, both sexes yielded milk, and thus nourished their young ; and in the case of the Marsupials, that both sexes carried their young in marsupial sacks. This will not appear altogether improbable, if we reflect that the males of existing syngnatbous fishes receive the eggs of the females in their abdominal pouches, hatch them, and afterwards, as some believe, nourish the young ; 80— that certain other male fishes hatch the eggs within their mouths or branchial cavities; — that certain male toads take the chaplets of eggs from the females, and wind them round their own thighs, keeping them there until the tadpoles are born;— that certain male birds undertake the whole duty of incubation, and that male pigeons, as well as the females, feed their nestlings with a secretion from their crops. But the above suggestion first occurred to me from the mammary glands of male mammals being so much more perfectly developed than the rudiments of the other accessory reproductive parts, which are found in the one sex though proper to the other. The mammary glands and nipples, as they exist in male mammals, can indeed hardly be called rudimentary ; they are merely not fully developed, and not functionally active. They are sympa- thetically affected under the influence of certain diseases, like the same organs in the female. They often secrete a few drops of milk at birth and at puberty : this latter fact occurred in the curious case, before referred to, where a young man possessed two pairs of mammae. In man and some other male mammals these organs have been known occasionally to become so well developed during maturity as to yield a fair supply of milk. Now if we suppose that during a former prolonged period male mammals aided the females in nursing their offspring,81 and that afterwards from some cause (as from the production of a smaller number of young) the males ceased to give this aid, disuse of the organs during maturity would lead to their becoming inactive ; and from two well-known principles of inheritance, this state of inactivity would probably be transmitted to the males at the corresponding ago of maturity. But at an earlier age these 80 Mr. Lockwood believes (as by Prof. Wyman, in ' Proc. Boston quoted in* Quart. Journal of Science,' Soc. of Nat. Hist.* Sept. 15,1857; April, 1868, p. 269), from what he also Prof. Turner, in 'Journal oi has observed of the development of Anat. and Phys/ Nov. .1, 1866, p. Hippocampus, that the walls of the 78. Dr. Giinther has likewise d§- abdominal pouch of the male in scribed similar cases, some way afford nourishment. On 31 Madlle. C. Royer has suggested male fishes hatching the ova in their a similar view in her *Origlrse de jcjouths, see a very interesting papcz PHomasb ' &c, 1870. M 2 X&4 The Descent of Man. Par* I, organs would be left unaffected, so that they would be almost equally well developed in the young of both sexes. Conclusion. — Von Baer has defined advancement or progress in the organic scale better than any one else, as resting on the amount of differentiation and specialisation of the several parts of a being, — when arrived at maturity, as I should be inclined to add. Now as organisms have become slowly adapted to diver- sified lines of Life by means of natural selection, their parts will have become more and more differentiated and specialised for various functions, from the advantage gained by the division of physiological labour. The same part appears often to have been modified first for one purpose, and then long afterwards for some other and quite distinct purpose ; and thus all the parts /are rendered more and more complex. But each organism still I retains the general type of structure of the progenitor from I which it was aboriginally derived. In accordance with this view it seems, if we turn to geological evidence, that organisa- tion on the whole has advanced throughout the world by slow and interrupted steps. In the great kingdom of the Vertebrata it has culminated in man. It must not, however, be supposed that groups of organic beings are always supplanted, and dis- appear as soon as they have given birth to other and more perfect groups. The latter, though victorious over their pre- decessors, may not have become better adapted for all places in the economy of nature. Some old forms appear to have survived from inhabiting protected sites, where they have not been exposed to very severe competition ; and these often aid us in constructing our genealogies, by giving us a fair idea of former and lost populations. But we must not fall into the error of looking at the existing members of any lowly-organised group as perfect representatives of their ancient predecessors. The most ancient progenitors in the kingdom of the Vertebrata, at which we are able to obtain an obscure glance, apparently consisted of a group of marine animals,32 resembling the larvae of existing Ascidians. These animals probably gave rise to a 82 The inhabitants of the sea- ditions for many generations, can shore must be greatly affected by hardly fail to run their course in the tides; animals living either regular weekly periods. Now it is a about the mean high-water mark, mysterious fact that in the higher or about the mean low-water mark, and now terrestrial Vertebrata, as *>a«s through a complete cycle of well as in other classes, many nor- tidal changes in a fortnight. Con- mal and abnormal processes have sequently, their food supply will one or more whole weeks as their undergo marked changes week by periods ; this would be rendered week. The vital functions of such intelligible if the Vertebrata are do- tiumals. living under these con- scended from an animal allied U Chap. VI. Affinities and Genealogy. 165 group of fishes, as lowly organised as the lancelet; and from these the Ganoids, and other fishes like the Lepidosiren, must nave been developed. From such fish a very small advauce would carry us on to the Amphibians. We have seen that birds and reptiles were once intimately connected together ; and the Monotremata now connect mammals with reptiles in a slight degree. But no one can at present say by what line of descent the three higher and related classes, namely, mammals, birds, and reptiles, were derived from the two lower vertebrate classes, namely, amphibians and fishes. In the class of mammals the stops are not difficult to conceive which led from the ancient Monotremata to the ancient Marsupials; and from these to the early progenitors of the placental mammals. We may thus ascend to the Lemuridse ; and the interval is not very wide from these to the Simiadae. The Simiad® then branched off into two great stems, the New World and Old World monkeys ; and from the latter, at a remote period, Man, the wonder and glory of the Universe, proceeded. Thus we have given to man a pedigree of prodigious length, but not, it may be said, of noble quality. The world, it has often been remarked, appears as if it had long been preparing for the advent of man : and this, in one sense is strictly true, for he owes his birth to along line of progenitors. If any single link in this chain had never existed, man would not have been exactly what he now is. Unless we wilfully close our eyes, we may, with our present knowledge, approximately recognise our parentage ; nor need we feel ashamed of it. The most humble organism is something much higher than the inorganic dust under our feet ; and no one with an unbiassed mind can study any living creature, however humble, without being struck with enthusiasm at its marvellous structure and properties. the existing tidal Ascidians. Many cess or function, would not, when instances of such periodic processes once gained, be liable to change; might be given, as the gestation of consequently it might be thus trans- mammals, the duration of fevers, &c. mitted through almost any number The hatching of eggs affords also a of generations. Bat if the function good example, for, according to Mr. changed, the period would have to Bartlett (* Land and Water,' Jan. 7, change, and would be apt to change 1871), the eggs of the pigeon are almost abruptly by a whole week, hatched in two weeks ; those of the This conclusion, if sound, is highly fowl in three ; those of the duck in remarkable ; for the period of gesta- fo ir ; those of the goose in five ; tion in each mammal, and the and those of the ostrich in seven hatching of each bird's eggs, and weeks. As far as we can judge, a many other vital processes, thus recurrent period, if approximately betray to us the primordial birfch- ©f the right duration for any pro- place of these animals. 1 66 The Descent of Man. Part I CHAPTER VII. On the Races of Man. Hie nature and value of specific characters — Application to tha races of man — Arguments in favour of, and opposed to, ranking the so-called races of man as distinct species — Sub-species — Monogenists and poly- genists — Convergence of character — Numerous points of resemblance in body and mind between the most distinct races of man — The state of man when he first spread over the earth — Each race not descended from a single pair — The extinction of races — The formation ot races — The effects of crossing — Slight influence of the direct action of the con- ditions of life — Slight or no influence of natural selection — Sexual selection. It is not my intention here to describe the several so-called races of men; but I am about to enquire what is the value of the dif- ferences between them under a classificatory point of view, and how they have originated. In determining whether two or more allied forms ought to be ranked as species or varieties, naturalists are practically guided by the following considerations; namely, the amount of difference between them, and whether such differences relate to few or many points of structure, and whether they are of physiological importance ; but more especially whether they are constant. Constancy of character is what is chiefly valued and sought for by naturalists. Whenever it can be shewn, or rendered probable, that the forms in question have remained distinct for a long period, this becomes an argument of much weight in favour of treating them as species. Even a slight degree of sterility between any two forms when first crossed, or in their offspring, is generally considered as a decisive test of their specific distinctness; and their continued persistence without blending within the same area, is usually accepted as sufficient evidence, either of some degree of mutual sterility, or in the case of animals of some mutual repugnance to pairing. Independently of fusion from intercrossing, the complete absence, in a well-investigated region, of varieties linking together any two closely-allied forms, is probably the most important of all the criterions of their specific distinctness ; and this is a somewhat different consideration from mere constancy j of character, for two forms may be highly variable and yet not I yield intermediate varieties. Geographical distribution is often brought into play unconsciously and sometimes consciously ; so that forms living in two widely separated areas, in which most Chap. VIL The Races of Man. 167 of ;fche other inhabitants are specifically distinct, are themselves usually looked at as distinct ; but in truth this affords 110 aid in dis- tinguishing geographical races from so-called good or true species. Now let us apply these generally-admitted principles to the races of man, viewing him in the same spirit as a naturalist would any other animal. In regard to the amount of difference between the races, we must make some allowance for our nice powers of discrimination gained by the long habit of observing ourselves. In India, as Elphinstone remarks, although a newly-arrived European cannot at first distinguish the various native races, yet they soon appear to him extremely dissimilar j1 and the Hindoo cannot at first perceive any difference between the several European nations. Even the most distinct races of man are much more like each other in form than would at first be sup posed ; certain negro tribes must be excepted, whilst others, as Dr. Kohlfs writes to me, and as I have myself seen, have Caucasian features. This general similarity is well shewn by the French photographs in the Collection Anthropologique du Museum de Paris of the men belonging to various races, the greater number of which might pass for Europeans, as many persons to whom I have shewn them have remarked. Neverthe- less, these men, if seen alive, would undoubtedly appear very distinct, so that we are clearly much influenced in our judgment by the mere colour of the skin and hair, by slight differences in the features, and by expression. There is, however, no doubt that the various races, when \ carefully compared and measured, differ much from each other, ! — as in the texture of the hair, the relative proportions of all parts ■ of the body,8 the capacity of the lungs, the form and capacity of \ the skull, and even in the convolutions of the brain.3 But it would be an endless task to specify the numerous points of difference. The races differ also in constitution, in acclimatisation and in liability to certain diseases. Their mental characteristics are likewise very distinct ; chiefly as it would appear in their emotional, but partly in their intellectual faculties. Every one who has had the opportunity of comparison, must have been 1 * History of India,' 1841, vol. i. * On the urged that the perfect fertility of the intercrossed races of man, I if established, would not absolutely preclude us from ranking Ithem as distinct species. Independently of fertility, the characters presented by the off- spring from a cross have been thought to indicate whether or not the parent-forms ought to be ranked as species or varieties ; but after carefully studying the evidence, I have come to the con- clusion that no general rules of this kind can be trusted. The ordinary result of a cross is the production of a blended or 14 'The Variation of Animals and sterile, it is scarcely possible that Plants under Domestication,' vol. ii. p. 109. I may here remind the reader that the sterility of species when crossed is not a specially- acquired quality, but, like the in- capacity of certain trees to be graft- ed together, is incidental on other acquired differences. The nature of these differences is unknown, but they relate more especially to the re- productive system, and much less so to external structure or to ordinary differences in constitution. One important element in the sterility of crossed species apparently lies in one or both having been long habi- tuated to fixed conditions ; for we know that changed conditions have a special influence on the repro- ductive system, and we have good reason to believe (as before re- marked) that the fluctuating ' con- ditions of domestication tend to eliminate that 'sterility which is so general with species, in a natural state, when crossed. It has else- where been shewn by me (ibid. vol. ii. p. 185, and ' Origin of Species' 5th edit. p. 317), that the sterility of crossed species has not been ac- quired through natural selection : we can see that when two forms have already been rendered very their sterility should be augmented by the preservation or survival of the more and more sterile indi- viduals ; for as the sterility in- creases, fewer and fewer offspring will be produced from which to breed, and at last only single in- dividuals will be produced, at the rarest intervals. But there is even a higher grade of sterility than this. Both Gartner and Kolreuter have proved that in genera of plants including many species, a series can be tbrmed from species which when crossed yield fewer and fewer seeds, to species which never pro- duce a single seed, but yet are affected by the pollen of the other species, as shewn by the swelling of the gevmen. It is here mani- festly impossible to select the more sterile individuals, which have al- ready ceased to yield seeds; so that the acme of sterility, when the germea alone is affected, cannot have been gained through selection. This acme, and no doubt the other grades of sterility, are the incidental results of certain unknown differ- ences in the constitution of the re- productive system of the specie* which are crossed, Chap. VJL The Races of Man. 173 intermediate form ; but in certain cases some of the offspring take closely after one parent-form, and some after the othei. This is especially apt to occur when the parents differ in characters which first appeared as sudden variations or monstrosities.15 I refer to this point, because Dr. Eohlfs informs me that he has frequently seen in Africa the offspring of negroes crossed with members of other races, either completely black or completely white, or rarely piebald. On the other hand, it is notorious that in America mulattoes commonly present an intermediate appearance. We have now seen that a naturalist might feel himself fully justified in ranking the races of man as distinct species ; for ho has found that they are distinguished by many differences in structure and constitution, some being of importance. These differences have, also, remained nearly constant for very long periods of time. Our naturalist will have been in some degree influenced by the enormous range of man, which is a great anomaly in the class of mammals, if mankind be viewed as a single species. He will have been struck with the distribution of the several so-called races, which accords with that of other undoubtedly distinct species of mammals. Finally, he might urge that the mutual fertility of all the races has not as yet been fully proved, and even if proved would not be an absolute proof of their specific identity. On the other side of the question, if our supposed naturalist were to enquire whether the forms of man keep distinct like ordinary species, when mingled together in large numbers in the same country, he would immediately discover that this was by no means the case. In Brazil he would behold an immense mongrel population of Negroes and Portuguese ; in Chiloe, and other parts of South America, he would behold the whole popu- lation consisting of Indians and Spaniards blended in various degrees.16 In many parts of the same continent he would meet with the most complex crosses between Negroes, Indians, and Europeans ; and judging from the vegetable kingdom, such triple crosses afford the severest test of the mutual fertility of the parent-forms. In one island of the Pacific he would find a small population of mingled Polynesian and English blood ; and in the Fiji Archipelago a population of Polynesian and Negritos 15 * The Variation of Animals,' success and energy of the Paulistaa &c, vol. ii. u. 92. in Brazil, who are a much crossed id M. de Quatrefages has given race 01 Portuguese and Indians, with (* Anthropolog. Review,' Jan. 1869, a mixture of the blood of othw p. 22) an interesting account of the races. 174 The Descent of Man. Pirn? I. crossed in all degrees. Many analogous cases could "be be adaed ; for instance, in Africa. Hence the races of man are not suf- t ficiently distinct to inhabit the same country without fusion ; \and the absence of fusion affords the usual and best test 01 | specific distinctness. Our naturalist would likewise be much disturbed as soon as he perceived that the distinctive characters of all the races were highly variable. This fact strikes every one on first beholding the negro slaves in Brazil, who have been imported from all parts of Africa. The same remark holds good with the Polynesians, and with many other races. It may be doubted whether any character can be named which is distinctive of a race and is constant. Savages, even within the limits of the same tribe, are not nearly so uniform in character, as has been often asserted. Hottentot women offer certain peculiarities, more strongly marked than those occurring in any other race, but these are known not to be of constant occurrence. In the several American tribes, colour and hairiness differ considerably; as does colour to a certain degree, and the shape of the features greatly, in the Negroes of Africa. The shape of the skull varies much in some races ;17 and so it is with every other character. Now all naturalists have learnt by dearly-bought experience, how rash it is to attempt to define species by the aid of inconstant characters. \But the most weighty of all the arguments against treating the races of man as distinct species, is that they graduate into each other, independently in many cases, as far as we can judge, of their having intercrossed. Man has been studied more carefully than any other animal, and yet there is the greatest possible diversity amongst capable judges whether he should be classed as a single species or race, or as two (Virey), as three (Jacquinot), as four (Kant), five (Blumenbach), six (Buffon), seven (Hunter), eight (Agassiz), eleven (Pickering), fifteen (Bory St. Vincent), sixteen (Desmoulins), twenty-two (Morton), sixty (Crawfurd), or as sixty-three, according to Burke.18 This diversity of judgment does not prove that the races ought not to be ranked as species, but it shews that they graduate into each 17 For instance with the abori- 18 See a good discussion on this giiies of America and Australia, subject in Waitz, * Introduct. to Prof. Huxley says (' Transact. Inter- Anthropology/ Eng. translat. 1863, nat. Congress of Prehist. Arch/ pp. 198-208, 227. I have taken 1868, p. 105) that the skulls of some of the above statements from many South Germans and Swiss are H. Tuttle's * Origin and Antiquity * as short and as broad as those of of Physical Man,* Boston, 1866, p. * thfc 1 artars," &c. 35. Crap. VlL The Races of Man. i?5 other, and that it is hardly possible to discover clear distinctive \ characters between them. Every naturalist who has had the misfortune to undertake the description of a group of highly varying organisms, has en- countered cases (I speak after experience) precisely like that of man ; and if of a cautious disposition, he will end by uniting all the forms which graduate into each other, under a single species ; for he will say to himself that he has no right to give names to objects which he cannot define. Cases of this kind occur in the Order which includes man, namely in certain genera of monkeys; whilst in other genera, as in Cercopithecus, most of the species can be determined with certainty. In the American genus Cebus, the various forms are ranked by some naturalists as species, by others as mere geographical races. Now if numerous specimens of Cebus were collected from all parts of South America, and those forms which at present appear to be specifically distinct, were found to graduate into each other by close steps, they would usually be ranked as mere varieties or \ races ; and this course has been followed by most naturalists with respect to the races of man. Nevertheless, it must be confessed that there are forms, at least in the vegetable king- dom,19 which we cannot avoid naming as species, but which are connected together by numberless gradations, independently of intercrossing. Some naturalists have lately employed the term " sub-species" to designate forms which possess many of the characteristics of true species, but which hardly deserve so high a rank. Now if we reflect on the weighty arguments above given, for raising the races of man to the dignity of species, and the insuperable diffi- culties on the other side in defining them, it seems that the term "sub-species" might here be used with propriety. But from J long habit the term "race" will perhaps always be employed. 1 The choice of terms is only so far important in that it is desirablo f to use, as far as possible, the same terms for the same degrees of" difference. Unfortunately this can rarely be done : for the larger genera generally include closely-allied forms, which can be distinguished only with much difficulty, whilst the smaller genera within the same family include forms that are perfectly distinct ; yet all must be ranked equally as species. So again, species within the same large genus by no means resemble each other to the same degree : on the contrary, some of them 19 Piof. Nageli has carefully de- has made analogous remarks on scribed several striking cases in his some intermediate forms in the 4 Botanische Mittheilungen/ B. ii. Compos: tse of N. America, 1S66, s. 294-369. Prof. Asa Gray I j6 The Descent of Man , Paw* I can generally be arranged in little groups round other species^ like satellites round planets.20 The question whether mankind consists of one or severa species has of late years been much discussed by anthropologists, who are divided into the two schools of monogenists and polygenists. Those who do not admit the principle of evolution, must look at species as separate creations, or as in some manner as distinct entities ; and they must decide what forms of man they will consider as species by the analogy of the method commonly pursued in ranking other organic beings as species. But it is a hopeless endeavour to decide this point, until some definition of the term "species'* is generally accepted; and the definition must not include an indeterminate element such as an act of creation. We might as well attempt without any definition to decide whether a certain number of houses should be called a village, town, or city. We have a practical illustration of the difficulty in the never-ending doubts whether many closely-allied mammals, birds, insects, and plants, which represent each other respectively in North America and Europe, should bo ranked as species or geographical races ; and the like holds true of the productions of many islands situated at some little distance from the nearest continent. Those naturalists, on the other hand, who admit the principle of evolution, and this is now admitted by the majority of rising men, will feel no doubt that all the races of man are descended from a single primitive stock ; whether or not they may think fit to designate the races as distinct species, for the sake of ex- pressing their amount of difference.21 With our domestic animals the question whether the various races have arisen from one or more species is somewhat different. Although it may be admitted that all the races, as well as all the natural species within the same genus, have sprung from the same primitive stock, yet it is a fit subject for discussion, whether all the domestic races of the dog, for instance, have acquired theii present amount of difference since some one species was first domesticated by man; or whether they owe some of their characters to inheritance from distinct species, which had already been differentiated in a state of nature. With man no such question can arise, for he cannot be said to have been domesticated at any particular period. During an early stage in the divergence of the races of man 70 * Origin of Species/ 5th edit, in the 'Fortnightly Review/ 1885, J\ 68. * p. 275. « See Pzot Hux1gy to this eSbet Chap. VII. The Races of. Man. 177 from a common stock, the differences between the races and their number must have been small; consequently as far as their distinguishing characters are concerned, they then had less claim to rank as distinct species than the existing so-called races. Nevertheless, so arbitrary is the term of species, that such early races would perhaps have been ranked by some naturab'sts as distinct species, if their differences, although extremely slight, had been more constant than they are at present, and had not graduated into each other. It is however possible, though far from probable, that the early progenitors of man might formerly have diverged much in character, until they became more unlike each other than any now existing races; but that subsequently, as suggested by Vogt,22 they converged in character. When man selects the off- spring of two distinct species for the same object, he sometimes induces a considerable amount of convergence, as far as general appearance is concerned. This is the case, as shewn by Von Nathusius,23 with the improved breeds of the pig, which are descended from two distinct species; and in a less marked manner with the improved breeds of cattle. A great anatomist, Gratiolet, maintains that the anthropomorphous apes do not form a natural sub-group; but that the orang is a highly developed gibbon or semnopithecus, the chimpanzee a highly developed macacus, and the gorilla a highly developed mandrill. If this conclusion, which rests almost exclusively on brain- characters, be admitted, we should have a case of convergence at least in external characters, for the anthropomorphous apes are certainly more like each other in many points, than they are to other apes. All analogical resemblances, as of a whale to a fish, may indeed be said to be cases of convergence ; but this term has never been applied to superficial and adaptive resem- blances. It would, however, be extremely rash to attribute to convergence close similarity of character in many points of structure amongst the modified descendants of widely distinct beings. The form of a crystal is determined solely by the mole- cular forces, and it is not surprising that dissimilar substances should sometimes assume the same form; but with organic beings we should bear in mind that the form of each depends on an infinity of complex relations, namely on variations, due to causes far too intricate to be followed, — on the nature of the variations preserved, these depending on the physicial condi- 22 * Lectures on Man,* Eng. trans- schichtc, &c, Schweineschadel, lat. 1864, p. 468. 1864, s. 104. With respect to catt!*, 26 'Die Racen des Schweines,' see M. de Quatrefages, 'Unite' de I860, s, 46 'Vorstadien fur Ge- l'EspeceHumaine/lSei, p. 119 1 7$ The Descent of Man. Part I. tions. and still more on the surrounding organisms which com- pete with each,— and lastly, on inheritance (in itself a fluctuating element) from innumerable progenitors, all of which have had their forms determined through equally complex relations. It appears incredible that the modified descendants of two organ • isms, if these differed from each other in a marked manner, should ever afterwards converge so closely as to lead to a near approach to identity throughout their whole organisation. In the case of the convergent races of pigs above referred to, evi- dence of their descent from two primitive stocks is, according to Von Nathusius, still plainly retained, in certain bones of their skulls. If the races of man had descended, as is supposed by some naturalists, from two or more species, which differed from each other as much, or nearly as much, as does the orang from the gorilla, it can hardly be doubted that marked differences in the structure of certain bones would still be discoverable in man as he now exists. . Although the existing races of man differ in many respects, as /in colour, hair, shape of skull, proportions of the body, &c, yet j if their whole structure be taken into consideration they are ' found to resemble each other closely in a multitude of points. Many of these are of so unimportant or of so singular a nature, that it is extremely improbable that they should have been inde- pendently acquired by aboriginally distinct species or races. The same remark holds good with equal or greater force with respect to the numerous points of mental similarity between the most distinct races of man. The American aborigines, Negroes and Europeans are as different from each other in mind as any three races that can be named; yet I was incessantly struck, whilst living with the Fuegians on board the " Beagle," with the many little traits of character, shewing how similar their minds were to ours; and so it was with a full-blooded negro with whom I happened once to be intimate. He who will read Mr. Tylor/s and Sir J. Lubbock's interesting works 24 can hardly fail to be deeply impressed with the close similarity between the men of all races in tastes, dispositions and habits. This is shewn by the pleasure which they all take in dancing, rude music, acting, painting, tattooing, and otherwise decorating themselves ; in their mutual comprehension of gesture- language, by the same expression in their features, and by the same inarticulate cries, when excited by the same emotions. This similarity, or rather identity, is striking, when contrasted ** Tylor's * Early History of Man- language, see p. 54. Lubbock'a kind/ 1865 : with respect to gestnre- ' Prehistoric .Times,* 2nd edit. 1 86& Chap. VII. The Races of Man. 179 with the different expressions and cries made by distinct species of monkeys. There is good evidence that the art of shooting with bows and arrows has not been handed down from any common progenitor of mankind, yet as Westropp and Nilsson have remarked,25 the stone arrow-heads, brought from the most distant parts of the world, and manufactured at the most remote periods, are almost identical ; and this fM-- ^n ™ily ha mw^intflfl l for bv_the various races having similar inventive or /mental ! \ powers. The same observation has been made by archaeologists 20 witETrespect to certain widely-prevalent ornaments, such as zig- zags, &c. ; and with respect to various simple beliefs and cus- toms, such as the burying of the dead under megalithic struc- tures. I remember observing in South America,27 that there, as in so many other parts of the world, men have generally chosen the summits of lofty hills, to throw up piles of stones, either as a record of some remarkable event, or for burying their dead. Now when naturalists observe a close agreement in numerous small details of habits, tastes, and dispositions between two or more domestic races, or between Nearly-allied natural forms, they use this fact as an argument that they are descended from a common progenitor who was thus endowed ; and consequently that all should be classed under the same species. The same argument may be applied with much force to the races of man. As it is improbable that the numerous and unimportant points of resemblance between the several races of man in bodily struct ture and mental faculties (I do not here refer to similar customs) should all have been independently acquired, they must havo been inherited from progenitors who had these same characters. We thus gain some insight into the early state of man, before he had spread step by step over the face of the earth. The spreading of man to regions widely separated by the sea, no doubt, pre- ceded any great amount of divergence of character in the several races ; for otherwise we should sometimes meet with the same race in distinct continents; and this is never the case. Sir J. Lubbock, after comparing the arts now practised by savages in all parts of the world, specifies those which man could not have known, when he first wandered from his original birth-place; for if once learnt they would never have been forgotten.28 He 25 'On Analogous Forms of Im- 'Journal of Ethnological Soc.' as plements/ in ' Memoirs of Anthropo- given in ' Scientific Opinion/ June log. Soc./ by H. M. Westropp. « The 2nd, 1869, p. 3. Primitive Inhabitants of Scaadi- 2r 'Journal of Researches: Voyags navia/ Eng. translat. edited by Sir of the "Beagle,"' p. 46. J. Lubbock, 1868, p. 104. 28 ' Prehistoric Times/ 1869, p, *• Westropp, ' On Cromlechs/ &c, 574. N 2 180 The Descent of Man. Part L thus shews that " the spear, which is but a development of the •' knife-point, and the club, which is but a long hammer, are the mans of New York ; and in most bers given. cases I have compaiea the Youmans 4* *The Indian Medical Gazette, figures with those given in several Nov. 1, 1871, p, 240. Chap. VII. TIu Extinction of Races. 189 inter-breeding ; but in the above cases infertility has coincided too closely with the arrival of Europeans for us to admit this explanation. Nor have we at present any reason to believe that man is highly sensitive to the evil effects of inter-breeding, especially in areas so large as New Zealand, and the Sandwich archipelago with its diversified stations. On the contrary, it is known that the present inhabitants of Norfolk Island are nearly all cousins or near relations, as are the Todas in India, and the inhabitants of some of the Western Islands of Scotland; and yet they seem not to have suffered in fertility.46 A much more probable view is suggested by the analogy of the lower animals. The reproductive system can be shewn to be susceptible to an extraordinary degree (though why we know not) to changed conditions of life *, and this susceptibility leads both to beneficial and to evil results. A large collection of facts on this subject is given in chap, xviii. of vol. ii. of my ' Variation of Animals and Plants under Domestication/ 1 can here give only the briefest abstract; and every one interested in the subject may consult the above work. Very slight changes increase the health, vigour and fertility of most or all organic beings, whilst other changes are known to render a large number of animals sterile. One of the most familiar cases, is that of tamed elephants not breeding in India; though they often breed in Ava, where the females are allowed to roam about the forests to some extent, and are thus placed under more natural conditions. The case of various American monkeys, both sexes of which have been kept for many years together in their own countries, and yet have very rarely or never bred, is a more apposite in- stance, because of their relationship to man. It is remarkable how slight a change in the conditions often induces sterility in a wild animal when captured ; and this is the more strange as all our domesticated animals have become more fertile than they were in a state of nature ; and some of them can resist the most unnatural conditions with undiminished fertility.46 Certain groups of animals are much more liable than others to be affected by captivity ; and generally all the species of the same group are affected in the same manner. But sometimes a single species in a group is rendered sterile, whilst the others are not bo ; on the other hand, a single species may retain its fertility 45 On the close relationship of the Scotland, Dr. Mitchell, * Edinburgh Norfolk Islanders, see Sir W. Deni- Medical Journal,' March to June, son, * Varieties of Vice-Regal Life/ 1865. vol. i. 1870, p. 410. For the Todas, 4S For the evidence on this head, see CoL Marshall's work, 1873, p. see 'Variation of Animals* &c, 110. For the Western Islands rtf vol, ii. p. Ill, 100 Tfte Descent cf Man. Part I. whilst most of the others fail to breed. The males and females of some species when confined, or when allowed to live almost, but not quite free, in their native country, never unite ; others thus circumstanced frequently unite but never produce offspring ; others again produce some offspring, but fewer than in a state of nature; and as bearing on the above cases of man, it is important to remark that the young are apt to be weak and sickly, or malformed, and to perish at an early age. Seeing how general is this law of the susceptibility of the reproductive system to changed conditions of life, and that it holds good with our nearest allies, the Quadrumana, I can hardly doubt that it applies to man in his primeval state. Hence if savages of any race are induced suddenly to change their habits of life, they become more or less sterile, and their young offspring suffer in health, in the same manner and from the same cause, as do the elephant and hunting-leopard in India, many monkeys in America, and a host of animals of all kinds, on removal from their natural conditions. We can see why it is that aborigines, who have long inha- bited islands, and who must have been long exposed to nearly uniform conditions, should be specially affected by any change in their habits, as seems to be the case. Civilised races can certainly resist changes of all kinds far better than savages; and in this respect they resemble domesticated animals, for though the latter sometimes suffer in health (for instance European dogs in India), yet they are rarely rendered sterile, though a few such instances have been recorded.47 The immunity of civilised races and domesticated animals is probably due to their having been subjected to a greater extent, and therefore having grown somewhat more accustomed, to diversified or varying conditions, than the majority of wild animals; and to their having formerly immigrated or been carried from country to country, and to different families or sub-races having inter-crossed. It appears that a cross with civilised races at once gives to an aboriginal race an immunity from the evil consequences of changed conditions. Thus the crossed offspring from the Tahitians and English, when settled in Pitcairn Island, increased so rapidly that the island was soon overstocked ; and in June 1856 they were removed to Norfolk Island. They then consisted of 60 married persons and 134 children, making a total of 194. Here they likewise in- creased so rapidly, that although sixteen of them returned to Pit- cairn Island in 1859, they numbered in January 1868, 300 souls; « 'Variation of Animals,' &;., vol. iL, p Ifi. Chap* VII. The Extinction of Races. 191 the males and females being in exactly equal numbers. 'What a contrast does this case present with that of the Tasmanians ; the Norfolk Islanders increased in only twelve and a half years from 194 to 300; whereas the Tasmanians decreased during fifteen years from 120 to 46, of which latter number only ten were children.48 So again in the interval between the census of 1866 and 1872 the natives of full blood in the Sandwich Islands decreased by 8081, whilst the half-castes, who are believed to be healthier in- creased by 847 ; but I do not know whether the latter number includes theroffspring from the half-castes, or only the half-castes of the first generation. The cases which I have here given all relate to aborigines, who have been subjected to new conditions as the result of the immigration of civilised men. But sterility and ill-health would probably follow, if savages were compelled by any cause, such as the inroad of a conquering tribe, to desert their homos and to change their habits. It is an interesting circumstance that the chief check to wild animals becoming domesticated, which implies the power of their breeding freely when first captured, and one chief check to wild men, when brought into contact with civilisation, surviving to form a civilised race, is the same, namely, sterility from changed conditions of life. Finally, although the gradual decrease and ultimate extinction of the races of man is a highly complex problem, depending on many causes which differ in different places and at different times ; it is the same problem as that presented by the extinc- tion of one of the higher animals — of the fossil horse, for in- stance, which disappeared from South America, soon afterwards to be replaced, Within the same districts, by countless troops . y^ of the Spanish horse. The New Zealander seems conscious of-"-*""' this parallelism, for he compares his future fate with that of jP the native rat now almost exterminated by the European rat. w Kf f\ Though the difficulty is great to our imagination, and really v#» c % great, if we wish to ascertain the precise causes and their \y J manner of action, it ought not to be so to our reason, as long as ^ f *\, we keep steadily in mind that the increase of each species and each race is constantly checked in various ways; so that if any ^ new check, even a slight one, be superadded, the race will surely \ K decrease in number; and decreasing numbers will sooner- or 48 These details are taken from May 29th, 1863. The following *The Mutineers of the " Bounty," * statements about the Sandwich Is- by Lady Belcher, 1870; and from landers are from the < Honolulu * Pitcaim Island,' ordered to be Gazette,' and from Mr. Coan. piinted by the House of Commons, y 192 The Descent of Man. Past 1 later lead to extinction ; the end, in most cases, being promptly determined by the inroads of conquering tribes. * On the Formation of the Races of Man. — In some cases tho I crossing of distinct races has led to the formation of a new race. The singular fact that Europeans and Hindoos, who belong to the same Aryan stock, and speak a language fundamentally the same, differ widely in appearance, whilst Europeans differ but little from Jews, who belong to the Semitic stock, and speak quite another language, has been accounted for by Broca,49 through certain Aryan branches having been largely crossed by indigenous tribes during their wide diffusion. When two u races in close contact cross, the first result is a heterogeneous * mixture : thus Mr. Hunter, in describing the Santali or hill-tribes of India, says that hundreds of imperceptible gradations may be traced " from the black, squat tribes of the mountains to the tall " olive-coloured Brahman, with his intellectual brow, calm nyes, "and high but narrow head;" so that it is necessary in courts of justice to ask the witnesses whether they are Santalis or Hindoos.60 Whether a heterogeneous people, such as the inhabi- tants of some of the Polynesian islands, formed by the crossing of two distinct races, with few or no pure members left, would ever become homogeneous, is not known from direct evidence. But as with our domesticated animals, a cross-breed can certainly / be fixed and made uniform by careful selection51 in the course of a few generations, we may infer that the free intercrossing of a heterogeneous mixture during a long descent would supply the place of selection, and overcome any tendency to reversion ; so that the crossed race would ultimately become homogeneous, though it might not partake in an equal degree of the characters * of the two parent-races. Of all the differences between the races of man, the colour of the skin is the most conspicuous and one of the best marked. Ii was formerly thought that differences of this kind could be accounted for by long exposure to different climates; but Tallas first shewed that this is not tenable, and he has since been followed by almost all anthropologists.52 This view has been rejected chiefly because the distribution of tho variously coloured races, most of whom must have long inhabited thei* 4^ ' On Anthropology/ transla- 5i PalJas, ' Act. Acad. St. Peters- ticn * Anthropolog. Review,' Jan. burg/ 1780, part ii. p. 69. He was 1368, p. 38. followed by Rudolphi, in his « Bey- 50 i The Annals of Rural Bengal/ trage zur Anthropologic/ 1812. j8fi8, p. 134. An excellent summary of the evi- 51 ' The Variation of Animals and dence is given by Godi on, ' De Plants under Domestication/ vol. ii. PEspece/ 1859, vol. ii. p. 246, &c. p. ys 4 Chai\ VII. The Formation of Races. 193 present homes, does not coincide with corresponding differenced of climate. Some little weight may be given to stich cases as that of the Dutch families, who, as we hear on excellent autho- rity,53 have not undergone the least change of colour after residing for three centuries in South Africa. An argument on the same side may likewise be drawn from the uniform appear- ance in various parts of the world of gipsies and Jews, though the uniformity of the latter has been somewhat exaggerated.64 A very damp or a very dry atmosphere has been supposed to be more influential in modifying the colour of the skin than mere heat ; but as D'Orbigny in South America, and Livingstone in Africa, arrived at diametrically opposite conclusions with respect to dampness and dryness, any conclusion on this head must bo considered as very doubtful.65 Various facts, which I have given elsewhere, prove that the colour of the skin and hair is sometimes correlated in a surpris- ing manner with a complete immunity from the action of certain vegetable poisons, and from the attacks of certain parasites. Hence it occurred to me, that negroes and other dark races might have acquired their dark tints by the darker individuals escaping from the deadly influence of the miasma of their native countries, during a long series of generations. I afterwards found that this same idea had long ago occurred to Dr. Wells.56 It has long been known that negroes, and even* mulattoes, are almost completely exempt from the yellow -fever, \ so destructive in tropical America.37 They likewise escape to a large extent the fatal intermittent fevers, that prevail along at least 2600 miles of the shores of Africa, and which annually cause one-fifth of the white settlers to die, and another fifth to return home invalided.58 This immunity in the negro seems to be partly inherent, depending on some unknown peculiarity of constitution, and partly the result of acclimatisation. Pouchet59 53 Sir Andrew Smith, as quoted the Historical Sketch (p. xvi.) to my by Knox, * Races of Man * 1850, p. . * Origin of Species.' Various cas^s 473. of colour correlated with constitu- 54 See De Quatrefages on this tional peculiarities are given in my head, * Revue des Cours Scienti- * Variation of Animals under Do- fiques,' Oct. 17, 1868, p. 731. mestication,' vol. ii. pp. 227, 335. 55 Livingstone's * Travels and Re- " See, for instance, Nott and searches in S. Africa/ 1857, pp. Gliddon, * Types of Mankind,' p. 68. 338, 329. D'Orbigny, as quoted by 6* Major Tulloch, in a paper read Godron, * De l'Espece,* vol. ii. p. before the Statistical Society, Apni 266. 20th, 1840, and given in the « Athe- 56 See a paper read before the naeum,' 1840, p. 353. Royal Soc. in 1813, and published M 'The Plurality of the Human in fcis.Essays in 1818. I have given Race ' (transiat.), 1864, p. 60. *a account of Dr. Wells' views in k 194 The Descent of Man. f ah* I. states that the negro regiments recruited near the Soudan, and oorrowed from the Viceroy of Egypt for the Mexican war, escaped the yellow-fever almost equally with the negroes origin- ally brought ffomfarious parts of Africa and accustomed to the climate of the "West Indies. That acclimatisation plays a part, is shewn by the many cases in which negroes have become some- what liable to tropical fevers, after having resided for some time in a colder climate.60 The nature of the climate under which the white races have long resided, likewise has some influence on them; for during the fearful epidemic of yellow-fever in Demerara during 1837, Dr. Blair found that the death-rate of the immigrants was proportional to the latitude of the country whence they had come. With the negro the immunity, as far as it is the result of acclimatisation, implies exposure during a prodigious length of time ; for the aborigines of tropical America who have resided there from time immemorial, are not exempt from yellow fever; and the Eev. H. B. Tristram states, that there are districts in Northern Africa which the native inhabit- ants are compelled annually to leave, though the negroes can remain with safety. That the immunity of the negro is in any degree correlated I with the colour of his skin is a mere conjecture : it may be 1 correlated with some difference in his blood, nervous system, or 1 other tissues. Nevertheless, from the facts above alluded to, and (from some connection apparently existing between complexion and a tendency to consumption, the conjecture seemed to me not improbable. Consequently I endeavoured, with but little success,61 to ascertain how far it holds good. The late Dr. 60 Quatrefages, * Unite de 1'Espece " is some limited degree of relation Humaine,' 1861, p. 205. Waitz, " between the colour of the races of * Iutroduct. to Anthropology/ trans- " man and the climate inhabited by lat. vol. i. 1863, p. 124. Living- " them ; the following investiga- stone gives analogous cases in his " tion seems worth consideration. * Travels.' " Namely, whether there is any re- 61 In the spring of 1862 I ob- " lation in Europeans between the tained permission from the Director- " colour of their hair, and their General of the Medical department " liability to the diseases of tropica! of the Army, to transmit to the " countries. If the surgeons of the surgeons of the various regiments " several regiments, when stationed on foreign service a blank table, " in unhealthy tropical districts, with the following appended re- " would be so good as first to count, marks, but I have received no re- " as a standard of comparison, how turns. " As several well-marked " many men, in the force whence " cases have been recorded with " the sick are drawn, have darii w our domestic animals of a relation " and light-coloured hair, and hah " between the colour of the dermal " of intermediate or doubtful tints ; u appendages and the constitution ; "w^ if a similar account were "and it being notorious that there " kept by the same medical gentle Ckap, VIL The Formation of Races. 195 Daniel], who had long lived on the West Coast of Africa, told me that he did not believe in any such relation. He was himself unusually fair, and had withstood the climate in a wonderful manner. When he first arrived as a boy on the coast, an old and experienced negro chief predicted from his appearance that this would prove the case. Dr. Nicholson, of Antigua, after having attended to this subject, writes to me that he does not think that dark-coloured Europeans escape the yellow-fever more than those that are light-coloured. Mr. J. M. Harris altogether denies that Europeans with dark hair withstand a hot climate better than other men : on the contrary, experience has taught him in making a selection of men for service on the coast oi Africa, to choose • those with red hair.62 As far, therefore, as these slight indications go, there seems no foundation for the hypothesis, that blackness has resulted from the darker and darker individuals having survived better during long exposure to fever-generating miasma. Dr. Sharpe remarks,63 that a tropical sun, which burns and blisters a white skin, does not injure a black one at all ; and, as he adds, this is not due to habit in the individual, for children only six or eight months old are often carried about naked, and are not affected. I have been assured by a medical man, that some years ago during each summer, but not during the winter, his hands became marked with light brown patches, like, *' men, of all the men who suffered " of generations." " from malarious anil yellow fevers, OT * Anthropological Review/ Jan. " or from dysentery, it would soon 1866, p. xxi. Dr. Sharpe also says, " be apparent, after some thousand with respect to India (* Man a Spe- " cases had been tabulated, whether cial Creation,' 1873, p. 118), that " there exists any relation between " it has been noticed by some medi- " the colour of the hair and consti- " cal officers that Europeans with " tutional liability to tropical dis- " light hair and florid complexions " eases. Perhaps no such relation " suffer less from diseases of tropical " would be discovered, but the in- " countries than persons with dark " vestigation is well worth making, "hair and sallow complexions; " In case any positive result were " and, so far as I know, there ap- " obtained, it might be of some " pear to be good grounds for this " practical use in selecting men for " remark." On the other hand, " any particular service. Theoreti- Mr. Heddle, of Sierra Leone " who " cally the result would be of high " has had more clerks killed under "interest, as indicating one means " him than any other man," by the " by which a race of men inhabiting climate of the West African Coast ** from a remote period an un- (W. Reade, * African Sketch Book/ " healthy tropical climate, might vol. ii. p. 522), holds a directly " have become dark-coloured by opposite view, as does Capt. Burton. "the better preservation of dark- 63 * Man a Special Creation/ 1873 " haired or dark-complexioned in- p. 119. * dividuals during a long succession o 2 196 The Descent of Matt. Pass? L although larger than freckles, and that these patches were nevei affected by sun-burning, whilst the white parts of his skin have on several occasions been much inflamed and blistered. With the lower animals there is, also, a constitutional difference in liability to the action of the sun between those parts of the skin clothed with white hair and other parts.64 Whether the saving of the skin from being thus burnt is of sufficient impor- tance to account for a dark tint having been gradually acquired by man through natural selection, I am unable to judge. If it be so, we should have to assume that the natives of tropical America have lived there for a much shorter time than the negroes in Africa, or the Papuans in the southern parts of the Malay archipelago, just as the lighter-coloured Hindoos have resided in India for a shorter time than the darker aborigines of the central and southern parts of the peninsula. Although with: our present knowledge jwe cannot account for the differences of colour in the races of man, through any advantage thus gained, or from the direct action of climate ; yet we must not quite ignore the latter agency, for there is good reason to believe that some inherited effect is thus produced^6 |" We have seen in the second chapter that the conditions of life j affect the development of the bodily frame in a direct manner, I and that the effects are transmitted. Thus, as is generally / admitted, the European settlers in the United States undergo a I slight but extraordinarily rapid change of appearance. Their bodies and limbs become elongated; and I hear from Co/. Bernys that during the late war in the United States, good evidence was afforded of this fact by the ridiculous appearance presented by the German regiments, when dressed in ready-made clothes manufactured for the American market, and which were much too long for the men in every way. There is, also, a con- siderable body of evidence shewing that in the Southern States the house-slaves of the third generation present a markedly different appearance from the field-slaves.63 6* Variation of Animab and settled in Georgia, hare acquired in .Plants under Domestication/ vol. ii. the course of two generations dark: pp. 336, 337. hair and eyes. Mr. D. Forbes in- 65 See, for instance, Quatrefages forms me that the Quichuas in th«s (* Revue des Cours Scientifiques/ Andes vary greatly in colour, ao Oct. 10, 1868, p. 724) on the effects cording io the position of the valleys of residence in Abyssinia and Arabia, inhabited by them. .'*nd other analogous cases. Dr. 66 Harlan, 'Medical Researches/ Rolle (' Der Mensch, seine Abstam- p. 532. Quatrefages (' Unite' d«? mung,' &c, 1865, s. 99) states, on 1'Espece Humaine,' 1861, p. 128) the authority of Khanikof, that the has collected much evidence on thia greater number of German families head. Chap. VII. The Formation of Races. 197 If, however, we look to the races of man as distributed over the world/we must infer that their characteristic differences can- not be accounted for by the direct action of different conditions of life, even after exposure to them for an enormous period of time. The Esquimaux live exclusively on animal food ; they are clothed in thick fur, and are exposed to intense cold and to prolonged darkness; yet they do not differ in any extreme degree from the inhabitants of Southern China, who live entirely on vegetable food, and are exposed almost naked to a hot, glaring climate. The unclothed Fuegians live on the marine produc- tions of their inhospitable shores; the Botocudos of Brazil wander about the hot forests of the interior and live chiefly on vegetable productions ; yet these tribes resemble each other so closely that the Fuegians on board the " Beagle " were mistaken by some Brazilians for Botocudos. The Botocudos again, as well as the other inhabitants of tropical America, are wholly different from the Negroes who inhabit the opposite shores of the Atlantic, are exposed to a nearly similar climate, and follow nearly the same habits of life. Nor can the differences between the races of man be accounted for by the inherited effects of the increased or decreased use of parts, except to a quite insignificant degree. Men who habitu- ally live in canoes, may have their legs somewhat stunted; those who inhabit lofty regions may have their chests enlarged ;j and those who constantly use certain sense-organs may have the cavities in which they are lodged somewhat increased in size, and their features consequently a little modified. With civilised nations, the reduced size of the jaws from lessened use — the habitual play of different muscles serving to express different emotions — and the increased size of the brain from greater intellectual activity, have together produced a considerable effect on their general appearance when compared with savages.^ Increased bodily stature, without any corresponding increase in the size of the brain, may (judging from the pre- viously adduced case of rabbits), have given to some races an elongated skull of the dolichocephalic type. Lastly, the little-understood principle of correlated develop- ment has sometimes come into action, as in the case of great muscular development and strongly projecting supra-orbital '' ridges. The colour of the skin and hair are plainly correlated, as * is the texture of the hair with its colour in the Mandans of North America.88 The colour also of the skin, and tho odour eT See Prof. Schaaffhausen, trans- 88 Mr. Catlin states (*N. Ameri- iat. in 'Anthropological Review,' can Indians,' 3rd edit. 1842, vol. 1. Oct. 1868, p. 439. p. 49) that in the whole tribe of 198 The Descent of Man, Part l emitted "by It, are likewise in some manner connected. With the breeds of sheep the number of hairs within a given space and the number of the excretory pores are related.®9 If we may judge from the analogy of our domesticated animals, many modifica- tions of structure in man probably come under this principle of correlated development. We have now seen that the external characteristic differences between the races of man cannot be accounted for in a satisfac- tory 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, ye are_ therefore led to_incjQiire whether slight individual differences. _to~ which man^is^ emi- nently IJableTmay not have been preserved an. grey hair, which is hereditary. 217. On the pores in the skin, Now this hair is as coarse and Dr. Wilckens, i Die Aufgaben der laarsh as that of a horse's mane, Landwirth. Zootechnik/ 18t'tf, s, 7* whilst the hair of other colours is Chap. VII. Structure of the Brain. 199 unknown agencies which induced them were to act in a more constant manner, aided by long-continued intercrossing. Such variations come under the provisional class, alluded to in our second chapter, which for the want of a better term are often called spontaneous. Nor do I pretend that the effects of sexual selection can be indicated with scientific precision ; but it can be shewn that it would be an inexplicable fact if man had not been modified by this agency, which appears to have acted powerfully on innumerable animals. It can further be shewn that thej differences between the races of man, as in colour, hairiness,/ form of features, &c, are of a kind which might have been/ expected to come under the influence of sexual selection. But in order to treat this subject properly, I have found it necessary to pass the whole animal kingdom in review. I have therefore devoted to it the Second Part of this work. At the close I shall return to man, and, after attempting to shew how far he has been modified through sexual selection, will give a brief summary of the chapters in this First Part. Note on the Resemblances and Differences in the? Structure and the Development of the Brain in Man and Apes. By Professor Huxley, F.R.S. The controversy respecting the nature and the extent of the differ- ences in the structure of the brain in man and the apes, which arose some fifteen years ago, has not yet come to an end, though the subject matter of the dispute is, at present, totally different from what it was formerly. It was originally asserted and re-asserted, with singular pertinacity, that the brain of all the apes, even the highest, differs from • that of man, in the absence of such conspicuous structures as the posterior lobes of the cerebral hemispheres, with the posterior cornu of the lateral ventricle and the hippocampus minor, contained in those lobes, which are so obvious in man. But the truth that the three structures in question are as well deve- loped in apes' as in human brains, or even better ; and that it is character- istic of all the Primates (if we exclude the Lemurs) to have these parts well developed, stands at present on as secure a basis as any proposition in comparative anatomy. Moreover, it is admitted by every one of the long series of anatomists who, of late years, have paid special attention to the arrangement of the complicated sulci and gyri which appear upon the surface of the cerebral hemispheres in man and the higher apes, that they are disposed after the very same pattern in him, ay in them. Every principal gyrus and sulcus of a chimpanzee's brain is clearly represented in that of a man, so that the terminology which applies to the one answers for the other. On this point there is no difference of opinion. Some years since, Professor Bischoff published a memoir 70 on the cerebral convolutions of man and apes; and as the purpose of my learned colleague was certainly not to diminish the value of the ™ 'Die Grosshirn-Windungen des Menschenj' * Abhandiucg^r der K Uayerischen Akaderpie.* Bl x., 1868. 200 The Descent of Man. pArt I differences between apes and men in this respect, I am glad to make a citation from him. " That the^ apes, and especially the orang, chimpanzee and gorilla, " come very close to man in their organisation, much nearer than to any *' other animal, is a well known fact, disputed by nobody. Looking at " the matter from the point of view of organisation alone, no one probably " would ever have disputed the view of Linnaeus, that man should be 44 placed, merely as a peculiar species, at the head of the mammalia and ot ** those apes. Both shew, in all theix- organs, so close an affinity, that the " most exact anatomical investigation is needed in order to demonstrate ** those differences which really exist. So it is with the brains. The " brains of man, the orang, the chimpanzee, the gorilla, in spite of all ** the important differences which they present, come very close to one "'another" (I.e. p. 101). There remains, then, no dispute as to the resemblance in fundamental characters, between the ape's brain and man's ; nor any as to the won- derfully close similarity between the chimpanzee, orang and man, in even the details of the arrangement of the gyri and sulci of the cerebral hemispheres. Nor, turning to the differences between the brains ot the highest apes and that of man, is there any serious question as to the nature and extent of these differences. It is admitted that the man's cerebral hemispheres are absolutely and relatively larger than those of the orang and chimpanzee ; that his frontal lobes are less excavated by the upward protrusion of the roof of the orbits ; that his gyri and sulci are, as a rule, less symmetrically disposed, and present a greater number of secondary plications. And it is admitted that, as a rule, in man, the temporo-occipital or " external perpendicular " fissure, which is usually so strongly marked a feature of the ape's brain is but faintly marked. But it is also clear, that none of these differences constitutes a sharp demarcation between the man's and the ape's brain. In respect to the external perpendicular fissure of Gratiolet, in the human brain, for instance, Professor Turner remarks :71 " In some brains it appears simply as an indentation of the margin of u the hemisphere, but, in others, it extends for some distance more or less " transversely outwards. I saw it in the right hemisphere of a female " brain pass more than two inches outwards ; and in another specimen, " also the right hemisphere, it proceeded for four-tenths of an inch out- u wards, and then extended downwards, as far as the lower margin of the " outer surface of the hemisphere. The imperfect definition of this fissure " in the majority of human brains, as compared with its remarkable dis- " tinctness in the brain of most Quadrumana, is owing to the presence, in " the former, of certain superficial, well marked, secondary convolutions '* which bridge it over and connect the parietal with the occipital lobe. *' The closer the first of these bridging gyri lies to the longitudinal " fissure, the shorter is the external parieto-occipital fissure." (1. c. p. 12.) The obliteration of the external perpendicular fissure of Gratiolet, therefore, is not a constant character of the human brain. On the other hand, its full development is not a constant character of the higher ape's brain. For, in the chimpanzee, the more or less extensive oblitera- tion of the external perpendicular sulcus by 4t bridging convolutions," ou ©ns side or the other, has been noted over and over again by Pro! " 'Convolutions of the Human Cerebrum Topographically Considered. '866, p. 12, Chap. VII. Structure of tlie Brain. 201 JJoIleston, Mr. Marshall, M. Broca and Professor Turner. At the conclusion of a special paper on this subject the latter writes :72 M The three specimens of the brain of a chimpanzee just described, w prove, that the generalisation which Gratiolet has attempted to draw of " the complete absence of the first connecting convolution and the " concealment of the second, as essentially characteristic features in the " brain of this animal, is by no means universally applicable. In only one " specimen did the brain, in these particulars, follow the law which " Gratiolet has expressed. As regards the presence of the superior bridg- " ing convolution, I am inclined to think that it has existed in one hemi- ** sphere, at least, in a majority of the brains of this animal which have, up " to this time, been figured or described. The superficial position of the " second bridging convolution is evidently less frequent, and has as yet, " I believe, only been seen in the brain (A) recorded in this cominuni- li cation. The asymmetrical arrangement in the convolutions of the ** two hemispheres, which previous observers have referred to in their u descriptions is also well illustrated in these specimens." (pp. 8, 9.) Even were the presence of the temporo-occipital, or external per- pendicular, sulcus a mark of distinction between the higher apes and man, the value of such a distinctive character would be rendered very doubtful by the structure of the brain in the Platyrhine apes. In fact while the temporo-occipital is one of the most constant of sulci in the Catarhine, or Old World, apes, it is never very strongly developed in the New World apes; it is absent in the smaller Platyrhini; rudimentary in Pithecia ;73 and more or less obliterated by bridging convolutions in Ateles. ■ A character which is thus variable within the limits of a single group can have no great taxonomie value. It is further established, that the degree of asymmetry of the convolu- tion of the two sides in the human brain is subject to much individual variation ; and that, in those individuals of the Bushman race who have been examined, the gyri and sulci of the two hemispheres are consider- ably less complicated and more symmetrical than in the European brain, while, in some individuals of the chimpanzee, their complexity and asymmetry become notable. This is particularly the case in the brain of a young male chimpanzee figured by M. Broca. (* L'ordre des Primates,' p. 165, fig. 11.) Again, as respects the question of absolute size, it is established that the difference between the largest and the smallest healthy human brain is greater than the difference between the smallest healthy human brain and the largest chimpanzees or orang's brain. Moreover, there is one circumstance in which the orang's and chim- panzee's brains resemble man's, but in which they differ from the lower apes, and that is the presence of two corpora candicantia — the Cynomorpha having but one. In view of these facts I do not hesitate in this year 1874, to repeat and insist upon the proposition which I enunciated in 1863.74 "So far as cerebral structure goes, therefore, it is clear that man n Notes more especially on the " Flower 'On the Anatomy of bridging convolutions in the Brain Pithecia MonacJius* ' Proceedings of of the Chimpanzee, 'Proceedings of the Zoological Society,' 1862. tiw Royal Society of Edinburgh,' :i < Man's PJace in Nature,' p. 102 1365-6. v 202 The Descent of Man. Paiit I, ** differs les3 from the chimpanzee or the orang, than these do even vt from the monkeys, and cnat the difference between the brain of the " chimpanzee and of man is almost insignificant, when compared with " that between the chimpanzee brain and that of a Lemur." In the paper to which I have referred, Professor Bischoff does not deny the second part of this statement, but he first makes the irrelevant remark that it is not wonderful if the brains of an orang and a Lemur are very different ; and secondly, goes on to assert that, " If we succes- * sively compare the brain of a man with that of an orang ; the brain of " this with that of a chimpanzee ; of this with that of a gorilla, and so " on of a Hylobates, Semnopithecus, Ggnocephalus, Cercopithecus, Macacus, " Cebus, Callithrix, Lemur, Stenops, Hapale, we shall not meet with a " greater, or even as great a, break in the degree of development of the "convolutions, as we find between the brain of a man and that of an. " orang or chimpanzee." To which I reply, firstly, that whether this assertion be true or false, it has nothing whatever to do with the proposition enunciated in 'Man's Place in Nature,' which refers not to the development of the convolutions alone, but to the structure of the whole brain. If Professor Bischoff had taken the trouble to refer to p. 96 of the work he criticises, in fact, he would have found the following passage : " And it is a " remarkable circumstance that though, so far as our present know- " ledge extends, there is one true structural break in the series of forms "of Simian brains, this hiatus does not lie between man and the " manlike apes, but between the lower and the lowest Simians, or in •' other words, between the Old and New World apes and monkeys and "the Lemurs. Every Lemur which has yet been examined, in fact, " has its cerebellum partially visible from above ; and its posterior lobe, " with the contained posterior cornu and hippocampus minor, more or "less rudimentary. Every marmoset, American monkey, Old World " monkey, baboon, or manlike ape, on the contrary, has ii3 cerebellum *' entirely hidden, posteriorly, by the cerebral lobes, and possesses a ** large posterior cornu with a well-developed hippocampus minor." This statement was a strictly accurate account of what was known when it was made; and it does not appear to me to be more than apparently weakened by the subsequent discovery of the relatively small development of the posterior lobes in the Siamang and in the Howling monkey. Notwithstanding the exceptional brevity of the posterior lobes in these two species, no one will pretend that their brains, in the slightest degree, approach those of the Lemurs. And if, instead of putting Hapale out of its natural place, as Professor Bischoff most unaccountably does, we write the series of animals he has chosen to mention as follows : Homo, Pithecus, Troglodytes, Hylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus, Callithrix, Hapale, Lemur, Stenops, I venture to reaffirm that the great break in this series lies between Hapale and Lemur*, and that this break is considerably greater than that between any other two terms of that series. Professor Bischoff ignores the fact that long before he wrote, Gratiolet had suggested the separation of the Lemurs from the other Primates on the very ground of the difference in their cerebral characters ; and that Professor Flower had made the following observations in the course of his description of the brain of the Javad Loris '* TS * Transactions of the Zoological Society,' vol. v. 1862. Chap. VII. Structure of the Brain. 203 " And it is especially remarkable that, in the development of the u posterior lobes, there is no approximation to the Lemurine, short " hemisphered, brain, in those monkeys which are commonly supposed •' to approach this family in other respects, viz., the lower members oi *' the Platyrhine group," So far as the structure of the adult brain is concerned, then, the very considerable additions to our knowledge, which have been made by the researches of so many investigators, during the past ten years, fully justify the statement which I made in 1863, But it has been said that, admitting the similarity between the adult brains of man and apes, they are nevertheless, in reality, widely different, because the? exhibit fundamental differences in the mode of their development. No one would be more ready than I to admit the 'force of this argument, if such fundamental differences of development really exist. But I deny that they do exist. On the contrary, there is a fundamental agree- ment in the development of the brain in men and apes. Gratiolet originated the statement that there is a fundamental difference in the development of the brains of apes and that of man — consisting in this ; that, in the apes, the sulci which first make their appearance are situated on the posterior region of the cerebral hemi- spheres, while, in the human foetus, the sulci first become visible on the frontal lobes.76 This general statement is based upon two observations, the one of a Gibbon almost ready to be born, in which the posterior gyri were " well " developed," while those of the frontal lobes were " hardly indicated "7r (1. c. p.. 39), and the.other of a human foetus at the 22nd or 23rd week of uterogestation, in which Gratiolet notes that the insula, was un- covered, but that nevertheless " des incisures sement 1e lobe anterieur, " une scissure peu profonde indique la separation du lobe occipital, tres- Vi " Chez tous les singes, les plis Rolando, and one of the frontal " posterieurs se deVeloppent les pre- sulci, plainly enough. Nevertheless, il miers ; les plis ant^rieurs se M. Alix, in his * Notice sur les " de>eloppent plus tard, aussi la travaux anthropologiques de Gratio- " vertebre occipitale et la parietale let' (Mern. de la Societe d'Anthrp- "sont-ellesrelativementtres-grandes pologie de Paris/ 1868, page 32. ), 44 chez le fetus. L'Homme presente writes thus : " Gratiolet a eu e litre 44 une exception remarquable quant " les mains le cerveau d'un fcetus de 44 a l'^poque de l'apparition des plis " Gibbon, singe erninemment su- " frontaux, qui sont les premiers " p^rieur, et tellement rapproche de " indiqu^s ; mais le developpement " l'orang, que des naturalistes tres- •* g^n^ral du lobe frontal, envisage " comp^tents Pont range parmi les " seulement par rapport a son " anthropo'ides. M. Huxley, par ex- " volume, suit les memeslois que dans " emple, n'hesite pas sur ce point. " les singes:" Gratiolet, 'Memoire " Eh bien, c'est sur le cerveau d'un sur les plis c£r<£braux de THomnie " fcetus de Gibbon que Gratiolet a et des Primates/ p. 39, Tab. iv. " vu les circonvolutions du lobe tern- fig. 3. " poro-sphenoidal deja developpees 77 Gratiolet's words are (1. c. p. " lor squ' il n' existent pas encore deplii 39): "Dans le fcetus dont il s'agit " sur le lobe frontal, II e"tait done " les plis cere*braux posterieurs sont " bien autorise" a dire que, cIipz " bien de>elopp£s, tandis que les " Phomme les circonvolutions appa- il plis du lobe frontal sont a peine " raissent d'a en to, tandis que chei ** indiqnes." the figure, however " les singes elles se d£velc*pent (Fl. iv. fie, 3\ shews the fissure of " d'ou ea «." 204 The Descent of Man. Part L u re'duit, d'ailleurs cles cette epoque. Le reste de la surface cerebrale " est encore absolument lisse." Three views of this brain are given in Plate II. figs, 1, 2, 3, of the work cited, shewing the upper, lateral and inferior views of the hemi- spheres, but not the inner view. It is worthy of note that the figure by no means bears out Gratiolet's description, inasmuch as the fissure (anterotemporal) on the posterior half of the face of the hemisphere; is more marked than any of those vaguely indicated in the anterior half. If the figure is correct it in no way justifies Gratiolet's conclusion : ** II y a done entre ces cerveaux [those of a Callithrix and of a Gibbon] et u celui du foetus humain une difference fondamental. Chez celui-ci, long- " temps avant que les plis temporaux apparaissent, les plis frontaux " essay ent d'exister." Since Gratiolet s time, however, the development of the gyri and sulci of the brain has been made the subject of renewed investigation by Schmidt, Bischoff, Pansch,78 and more particularly by Ecker,79 whose work is not only the latest, but by far the most complete, memoir on the subject. The final results of their inquiries may be summed up as follows : — 1. In the human foetus, the sylvian fissure is formed in the course of the third month of uterogestation. In this, and in the fourth month, the cerebral hemispheres are smooth and rounded (with the exception of the sylvian depression), and they project backwards far beyond the cerebellum. 2. The sulci, properly so called, begin to appear in the interval between the end of the fourth and the beginning of the sixth month of foetal life, but Ecker is careful to point out that, not only the time, but the order, of their appearance is subject to considerable individual variation. In no case, however, are either the frontal or the temporal sulci the earliest. The first which appears, in fact, lies on the inner face of the hemi- sphere (whence doubtless Gratiolet, who does not seem to have examined that face in his foetus, overlooked it), and is either the internal perpen- dicular (occipito-parietal), or the calcarine sulcus, these two being close together and eventually running into one another. As a rule the occipito-parietal is the earlier of the two. 3. At the latter part of this period, another sulcus, the " posterio, parietal," or " Fissure of Kolando " is developed, and it is followed, in the' course of the sixth month, by the other principal sulci of the frontal, parietal, temporal and occipital lobes. There is, however, no clear evidence that one of these constantly appears before the other and it is remarkable that, in the brain at the period described and figured by Ecker (I. c. p. 212-13, Taf. II. figs. 1, 2, 3, 4), the antero- temporal sulcus (scissure paralUle) so characteristic of the ape's brain, is as well, if not better developed than the fissure of Kolando, and is much more marked than the proper frontal sulci. Taking the facts as they now stand, it appears to me that the order of the appearance of the sulci and gyri in the foetal human brain is in perfect harmeny with the general doctrine of evolution, and with the 78 ' Ueber die typische Anordnung 79 ' Zur Entwickelcmgs Geschichte der Furchen und Windungen auf der Furchen und Windungen der den Grosshirn-Hemisp^aren des Grosshirn-Hemispharen im Foetus Meuschen und der Affen.' 'Archiv des MenscheD.' l Archiv fiir Antbro fur Anthropologic,' uh, 1868. pologio,' in., 1868. Chap. Vli. Structure of the Brain. 2oJ view that man has been evolved from some ape- like form ; though thero Can be no doubt that that form was, in many respects, different from any member of the Primates now living. Von Baer taught us, half a century ago, that, in the course of theii development, allied animals put on, at first, the characters of the greater groups to which they belong, and, by degrees, assume those which restrict them within the limits of their family, genus, and species ; and he proved, at the same time, that no developmental stage of a higher animal is precisely similar to the adult condition of any lower animal. It is quite correct to say that a frog passes through the condition of a fish, inasmuch as at one period of its life the tadpole has all the cha- racters of a fish, and, if it went no further, would have to be grouped among fishes. But it is equally true that a tadpole is very different from any known fish. In like manner, the brain of a human foetus, at the fifth month, may correctly be said to be, not only the brain of an ape, but that of an Arctopithecine or marmoset-like ape ; for its hemispheres, with their great posterior lobster, and with no sulci but the sylvian and the calcarine, present the characteristics found only in the group of the Arctopithecine Primates. But it is equally true, as Gratiolet remarks, that, in its widely open sylvian fissure, it differs from the brain of any actual marmoset. No doubt it would be much more similar to the brain of an advanced foetus of a marmoset. But we know nothing whatever of the development of the brain in the marmosets. In the Platyrhini proper, the only observation with which I am acquainted is due to Pansch, who found in the brain of a fcetal Cebus Apella, in addition to the sylvian fissure and the deep calcarine fissure, only a very shallow anterotemporal fissure (scissure parallele of Gratiolet.) Now this fact, taken together with the circumstance that the antero- temporal sulcus is present in such Platyrhini as the Saimiri, which present mere traces of sulci on the anterior half of the exterior of the cerebral hemispheres, or none at all, undoubtedly, so far as it goes, affords fair evidence in favour of Gratiolet's hypothesis, that the posterior sulci appear before the anterior, in the brains of the Platyrhini. But, it by no means follows, that the rule which may hold good for the Platyrhini extends to the Catarhini. We have no in- formation whatever respecting the development of the brain in the Cynnmorpha; and, as regards the Anthropomorpha, nothing but the account of the brain of the Gibbon, near birth, already referred to. At the present moment, there is not a shadow of evidence to shew that the sulci of a chimpanzee's, or orang's, brain do not appear in the same order as a man's. Gratiolet opens his preface with the aphorism. *' II est dangereux " dans les sciences de conclure trop vite." I fear he must have for- gotten this sound maxim by the time he had reached the discussion of the differences between men and apes, in the body of his work.. Nc doubt, the excellent author of one of the most remarkable contributions to the just understanding of the mammalian brain which has ever been made, would have been the first to admit the insufficiency of his data had he lived to profit by the advance of inquiry. The misfortune is that his conclusions have been employed by persons incompetent to appreciate their foundation, as arguments in favour of obscurantism.80 80 For example, M. l'Abb Chap. VII L Sexual Selection, 217 polygamous, but with animals belonging to the lower classes 1 have found no evidence of this habit. The intellectual powers of such animals are, perhaps, not sufficient to lead them to collect and guard a harem of females. That some relation exists between polygamy and the development of secondary sexual characters, appears nearly certain ; and this supports the view that a numerical preponderance of males would be eminently favourable to the action of sexual selection. Nevertheless many animals, which are strictly monogamous, especially birds, display Strongly-marked secondary sexual characters ; whilst some few animals, which are polygamous, do not have such characters. We will first briefly run through the mammals, and then tun; to birds. The gorilla seems to be polygamous, and the male differs considerably from fhe female ; so it is with some baboons, which live in herds containing twice as many adult females as males. In South America the Mycetes car ay a presents well- marked sexual differences, in colour, beard, and vocal organs ; and the male generally lives with two or three wives: the male of the Cebus capucinus differs somewhat from the female, and appears to be polygamous.10 Little is known on this head with respect to most other monkeys, but some species are strictly monogamous. The ruminants are eminently polygamous, and they present sexual differences more frequently than almost any other group of mammals; this holds good, especially in their weapons, but also in other characters. Most deer, cattle, and sheep are polygamous; as are most antelopes, though some are monogamous. Sir Andrew Smith, in speaking of the antelopes of South Africa, says that in herds of about a dozen there was rarely more than one mature male. The Asiatic Aniilope saiga appears to be the most inordinate polygamist in the world ; for Pallas11 states that the male drives away all rivals, and collects a herd of about a hundred females and kids together ; the female is hornless and has softer hair, but does not otherwise differ much from the male. The wild horse of the Falkland Islands and of the Western States of N. America is polygamous, but, except in his greater size and in the proportions of his body, differs but little from the mare. The wild boar presents well-marked sexual 10 On the Gorilla, Savage and Fasc. xii. 1777, p. 29. Sir Andrew Wyman * Boston Journal of Nat. Smith, * Illustrations of the Zoology Hist.' vol. v. 1845-47, p. 423. On of S. Africa/ 1849, pi. 29, on the Cynocephalus, Brehm, * Illust. Thier- Kobus. Owen, in his ' Anatomy of leben,' B. i. 1864, s. 77. On My- Vertebrates ' (vol. iii. 1868, p. 633) cetes, Rengger, 'Naturgesch.: Sauge- gives a table shewing incidentally thiere von Paraguay,' 1830, s. 14, which species of antelopes are gre- 2Q. Cebus, Brehm, ibid. s. 108. garious. 11 Pallas, 'Spicilegia Zoolog., 2 1 8 The Descent of Man. i'art LI, characters, in his great tusks and some other points. In Europe and in India he leads a solitary life, except during the breeding- season ; but as is believed by Sir W. Elliot, who has had many opportunities in India of observing this animal, he consorts at this season with several females. Whether this holds good in Europe is doubtful, but it is supported by some evidence. The adult male Indian elephant, like the boar, passes much of his time in solitude ; but as Dr. Campbell states, when with others, " it is rare to find more than one male with a whole herd " of females ;" the larger males expelling or killing the smaller and weaker ones. The male differs from the female in his immense tusks, greater size, strength, and endurance; so great is the difference in these respects, that the males when caught are valued at one-fifth more than the females.12 The sexes of other pachydermatous animals differ very little or not at all, and, as far as known, they are not polygamists. Nor have I heard of any species in the Orders of Cheiroptera, Edentata, Insectivora and Bodents being polygamous, excepting that amongst the Rodents, the common rat, according to some rat-catchers, lives with several females. Nevertheless the two sexes of some sloths (Edentata) differ in the character and colour of certain patches of hair on their shoulders.13 And many kinds of bats (Cheiroptera) present well-marked sexual differences, chiefly in the males possessing odoriferous glands and pouches, and by their being of a lighter colour.14 In the great order of Eodents, as far as I can learn, the sexes rarely differ, and when they do so, it is but slightly in the tint of the fur. As I hear from Sir Andrew Smith, the lion in South Africa sometimes lives with a single female, but generally with more, and, in one case, was found with as many as five females ; so that he is polygamous. As far as I can discover, he is the only polygamist amongst all the terrestrial Carnivora, and he alone presents well-marked sexual characters. If, however, we turn to the marine Carnivora, as we shall hereafter see, the case is widely different ; for many species of seals offer extraordinary sexual differences, and they are eminently polygamous. Thus, according to Peron, the male sea-elephant of the Southern Ocean always possesses several females, and the sea-lion of Forster is said to be surrounded by from twenty to thirty females. In the North, the male sea-bear of Steller is accompanied by even a 12 Dr. Campbell, in * ?roc. Zoo- 1S Dr. Gray, in ' Annals an J log. Soc.' 1869, p. 138, See also an Mag. of Nat. Hist.' 1871, p. 302. interesting paper, by Lieut. Johii- 14 See Dr. Dobson's excellent stone, in ' Proc. Asiati' Soc. of paper, in * Proc. Zoolog. Soc/ 1S73. Bengal/ May. 1868. p. 241. Chap. \ ill. Sexual Selection. 2ig greater number of females. It is an interesting fact, as Dr. Gill remarks,15 that in the monogamous species, "or those u living in small communities, there is little difference in size " between the males and females ; in the social species, or rather * those of which the males have harems, the males are vastly " larger than the females." Amongst birds, many species, the sexes of which differ greatly from each other, are certainly monogamous. In Great Britain we see well-marked sexual differences, for instance, in the wild- duck which pairs with a single female, the common blackbird, and the bullfinch which is said to pair for life. . I am informed by Mr. Wallace that the like is true of the Chatterers or Cotingidae of South America, and of many other birds. In several groups I have not been able to discover whether the species are polygamous or monogamous.. Lesson says that birds of paradise, so remarkable for their sexual differences, are polygamous, but Mr. Wallace doubts whether he had sufficient evidence. Mr. Salvia tells me he has been led to believe that humming-birds are polygamous. The male widow-bird, remarkable for his caudal plumes, certainly seems to be a polygamist.16 I have been assured by Mr. Jenner Weir and by others, that it is somewhat common for three starlings to frequent the same nest; but whether this is a case of polygamy or polyandry has not been ascertained. The Gallinaceae exhibit almost as strongly marked sexual differences as birds of paradise or humming-birds, and many of the species are, as is well known, polygamous; others being strictly monogamous. What a contrast is presented between the sexes of the polygamous peacock or pheasant, and the mono- gamous guinea-fowl or partridge ! Many similar cases could be given, as in the grouse tribe, in which the males of the poly- gamous capercailzie and black-cock differ greatly from the females ; whilst the sexes of the monogamous red grouse and ptarmigan differ very little. In the Cursores, except amongst the bustards, few species offer strongly-marked sexual dif- ferences, and the great bustard (Otis tarda) is said to be poly- gamous. With the Grallatores, extremely few species differ sexually, but the ruff (Machetes jpugnax) affords a marked 15 The Eared Seals, « American Great Bustard, see L. Lloyd, 'Game Naturalist,' vol. iv., Jan. 1871. Birds of Sweden,' 1867, p. 19, and 16 ' The Ibis,' vol. iii. 1861 p. 182. Montagu and Selby speak of 133, on the Progne Widow-bird. the Black Grov.«e as polygamous See also on the Vidua axillaris^ and of the Red Grouse as mono- ibid. vol. ii. 1860, p. 211. On the gamous. polygamy of the Capercailzie and 220 The Descent of Man, Part II. exception, and this species is believed by Montagu to be a polygamist. Hence it appears that amongst birds there often exists a close relation between polygamy and the development of strongly-marked sexual differences. I asked Mr. Bartlett, of the Zoological Gardens, who has had very large experience with birds, whether the male tragopan (one of the Gallinaceae) was polygamous, and I was struck by his answering, "I do not " know, but should think so from his splendid colours." It deserves notice that the instinct of pairing with a single female is easily lost under domestication. The wild-duck is strictly monogamous, the domestic-duck highly polygamous. The Kev. W. D. Fox informs me that out of some half-tamed wild-ducks, on a large pond in his neighbourhood, so many mallards were shot by the gamekeeper that only one was left for every seven or eight females ; yet unusually large broods were reared. The guinea-fowl is strictly monogamous ; but Mr. Fox finds that his birds succeed best when he keeps one cock to two or three hens. Canary-birds pair in a state of nature, but the breeders in England successfully put one male to four or five females. I have noticed these cases, as rendering it probable that wild monogamous species might readily become either temporarily or permanently polygamous. Too little is known of the habits of reptiles and fishes to enable us to speak of their marriage arrangements. The stickle-back (Gasterosteus), however, is said to be a polygamist;17 and the male during the breeding season differs conspicuously from the female. To sum up on the means through which, as far as we can judge, sexual selection has led to the development of secondary sexual characters. It has been shewn that the largest number of vigorous offspring will be reared from the pairing of the strongest and best-armed males, victorious in contests over other males, with the most vigorous and best-nourished females, which are the first to breed in the spring. If such females select the more attractive, and at the same time vigorous males, they will 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 females ; and this will especially hold good if the male defends the female, and aids in providing food for the young. The ad- vantage thus gained by the more vigorous pairs in rearing a larger number of offspring has apparently sufficed to render sexual selection efficient. But a large numerical preponderance 17 Ncel Humphreys, < River Gardens/ 1857. Chap. VIII. Sexual Selection. 221 of males over females will be still more efficient ; whether the preponderance is only occasional and local, or permanent; whether it occurs at birth, or afterwards from the greater de- struction of the females ; or whether it indirectly follows from the practice of polygamy. The Male generally more modified than the Female. — Throughout the animal kingdom, when the sexes differ in external appearance, it is, with rare exceptions, the male which has been the more modified ; for, generally, the female retains a closer resemblance to the young of her own species, and to other adult members of the same group. £lhe cause of this seems to lie in the males of almost all animals having stronger passions than the females] Hence it is the males that fight together and sedulously display their charms before the females ; and the victors transmit their superiority to their male ofifspringj Why both sexes do not thus acquire the characters of their fathers, will be considered here- after. That the males of all mammals eagerly pursue the females is notorious to every one. So it is with birds ; but many cock birds do not so much pursue the hen, as display their plumage, perform strange antics, and pour forth their song in her presence. The male in the few fish observed seems much more eager than the female ; and the same is true of alligators, and apparently of Batrachians. Throughout the enormous class of insects, as Kirby remarks,18 " the law is, that the male shall seek " the female." Two good authorities, Mr. Blackwall and Mr. C. Spence Bate, tell me that the males of spiders and crustaceans are more active and more erratic in their habits than the females. When the organs of sense or locomotion are present in the one sex of insects and crustaceans and absent in the other, .or when, as is frequently the case, they are more highly developed in the one than in the other, it is, as far as I can discover, almost invariably the male which retains such organs, or has them most developed ; and this shews that the male is the more active member in the courtship of the sexes.19 18 Kirby and Spence, ' Introduc- females of this species are impreg- tion to Entomology/ vol. iii. 1826, nated by the males which are born p. 342. in the same cells with them ; but 19 One parasitic Hymenopterous it is much more probable that the insect (Westwood, ' Modern Class, of females visit other cells, so that Insects/ vol. ii. p. 160) forms an close interbreeding is thus avoided, exception to the rul*, as the male We shall hereafter meet in various has rudimentary wings, and never classes, with a few exceptional eises, quits the cell in which it is born, in which the female, instead of the whilst the female has well-developed male, is the seeker and wooer, wings. Audouin believes that the 222 The Descent of Man. Part II. The female, on the other hand, with the rarest exceptions, is less eager than the male. As the illustrious Hunter w long ago observed, she generally " requires to be courted ;" she is coy, and may often be seen endeavouring for a long time to escape from the male. Every observer of the habits of animals will be able to call to mind instances of this kind. It is shown by various facts, given hereafter, and by the results fairly attributable to sexual selection, that the female, though comparatively passive, generally exerts some choice and accepts one male in preference to others. Or she may accept, as appearances would sometimes lead us to believe, not the male which is the most attractive to her, but the one which is the least distasteful. The exertion of some choice on the part of the female seems a law almost as general as the eagerness of the male. We are naturally led to enquire why the male, in so many and such distinct classes, has become more eager than the female, so that he searches for her, and plays the more active part in court- ship. It would be no advantage and some loss of power if each sex searched for the other; but why should the male almost always be the seeker? The ovules of plants after fertili- sation have to be nourished for a time; hence the pollen is necessarily brought to the female organs— being placed on the stigma, by means of insects or the wind, or by the spontaneous movements of the stamens ; and in the Algae, &c, by the loco- motive power of the antherozooids. With lowly-organised aquatic animals, permanently affixed to the same spot and having their sexes separate, the male element is invariably brought to the female ; and of this we can see the reason, for even if the ova were detached before fertilisation, and did not require subsequent nourishment or protection, there would yet be greater difficulty in transporting them than the male element, because, being larger than the latter, they are produced in far smaller numbers. So that many of the lower animals are, in this re- spect, analogous with plants.21 The males of affixed and aquatic animals having been led to emit their fertilising element in this way, it is natural that any of their descendants, which rose in the scale and became locomotive, should retain the same habit ; and they would approach the female as closely as pos- sible, in order not to risk the loss of the fertilising element in a long passage of it through the water. With some few of the lower 20 { Essays and Observations.* of the male and female reproductive edited by Owen, vol. i. 1861, r. cells, remarks, " verh'alt sich die 194. u erne bei der Vereinigung activ, 21 Prof. Sachs (' Lehrbuch de.- "... die andere erscheint bei del Botanik/ 1870, s. 633) in speaking " Vereinigung passiv." Chap. VIII. Sexual Selection. 223 animals, the females alone are fixed, and the males of these must be the seekers. But it is difficult to understand why the males of species, of which the progenitors were primordially free, should invariably have acquired the habit of approaching the females, instead of being approached by them. But in all cases, in order that the males should seek efficiently, it would be necessary that they should be endowed with strong passions; and the acquire- ment of such passions would naturally follow from the more eager leaving a larger number of offspring than the less eager. The great eagerness of the males has thus indirectly led to their much more frequently developing secondary sexual characters than the females. But the development of such characters would be much aided, if the males were more liable to vary than the females — as I concluded they were — after a long study of domesticated animals. Von Nathusius, who has had very wide experience, is strongly of the same opinion.22 Good evidence also in favour of this conclusion can be produced by a comparison of the two sexes in mankind. During the Novara Expedition 2S a vast number of measurements was made of various parts of the body in different races, and the*men were found in almost every case to present a greater range of variation than the women ; but I shall have to recur to this subject in a future chapter. Mr. J. Wood,24 who has carefully attended to the variation of the muscles in man, puts in italics the conclusion that " the greatest number of *' abnormalities in each subject is found in the males." He had previously remarked that ''altogether in 102 subjects, the varieties " of redundancy were found to be half as many again as in " females, contrasting widely with the greater frequency of " deficiency in females before described." Professor Macalister likewise remarks ^ that variations in the muscles " are probably " more common in males than females." Certain muscles which are not normally present in mankind are also more frequently developed in the male than in the female sex, although exceptions to this rule are said to occur. Dr. Burt Wilder 26 has tabulated the cases of 152 individuals with supernumerary digits, of which 86 were males, and 39, or less than half, females, the remaining 27 being of unknown sex. It should not, however, be overlooked 22 * Vortrage Uber Viehzucht,* my « Variation of Animals and 1872, p. 63. Plants under Domestication,' vol, ii. 23 < Reise der Novara: Anthro- 1868, p. 75. polog. Theil,' 1867, s. 216-269. 24 c Proceedings Royal Soc.' vol. The results were calculated by Dr. xvi. July 1868, pp. 519 and 524. Weisbach from measuiements made 25 •f the Kagistrar-General for 1866.* cennial table is given. CstA*. VtiL Proportion of the Sexes. 24$ Faye states " that iD some districts of Norway there has been " during a decennial period a steady deficiency of boys, whilst c' 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 department, and six times in another, that the female births have exceeded the males. In Eussia the average proportion is as high as 108*9, and in Philadelphia in the United States as 110*5 to 100.49 The average ibr Europe, deduced by Bickes from about seventy million births, is 106 males to 100 females. On the other hand, with white^ children born at the Cape of Good Hope, the proportion of males is so low as to fluctuate during successive years between 90 and 99 males for every 100 females. 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, for instance, in Livonia as 104 to 100.59 Prof. Faye remarks that " 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-torn females, we have in several countries " from 134*6 to 144*9 still-born males. During the first four or " five years of life, alrco, more male children die than females ; " for example in England, during the first year, 126 boys die for " every 100 girls— a proportion which in France is still more " unfavourable."51 Dr. Stockton-Hough accounts for these facts in part by the more frequent defective development of males than of females. "We have before seen that the male sex is more 49 For Norway and Russia, see 343. Dr. Stark also remarks abstract of Prof. Faye's researches, (' Tenth Annual Report of Births, in • British and Foreign Medico- Deaths. &c, in Scotland/ 1867, p. Chirurg. Review/ April, 1867, pp. xxviii.) that "These examples may 343, 345. For France, the ' An- " suffice to shew that, at almost nuaire pour l'An 1867/ p. 213. " every stage of life, the males in For Philadelphia, Dr. Stockton- " Scotland have a greater liability Hough, * Social Science Assoc.' 1874. " to death and a higher death-rate For the Cape of Good Hope, Quetelet " than the females. The fact, how- as quoted by Dr. H. H. Zouteveen, "ever, of this peculiarity being in the Dutch Translation of this " most strongly developed at that work (vol. i. p. 417), where much " infantile period of life when the information is given on the propor- " dress, food, and general treatment tion of the sexes. " of both sexes are alike, seems tc 60 In regard to the Jews, see M. " prove that the higher male death- Thurv, * La Loi de Production des " rate is an impressed, natural, and Sexes/ 1863, p. 25. " constitutional peculiarity due tc 11 * British and Foreign Medico- " sex alone." Qururg. Review/ April, 1867, p. B 2 244 The Descent of Man. Pae* li variable in structure than the female; and variations in im- portant organs would generally be injurious. But the size of the body, and especially of the head, being greater in male than iemale infants is another cause; for the males are thus more liable to be injured during parturition. Consequently the still- born males are more numerous; and, as a highly competent judge, Dr. Crichton Browne,62 believes, male infants often suffer in health for some years after birth. Owing to this excess in the death- rate of male children, both at birth and for some time sub- sequently, and owing to the exposure of grown men to various dangers, and to their tendency to emigrate, the females in all old-settled countries, where statistical records have been kept,63 are found to preponderate considerably over the males. It seems at first sight a mysterious fact that in different nations, under different conditions and climates, in Naples, Prussia, Westphalia, Holland, France, England and the United States, the excess of .male over female births is less when they are illegitimate than when legitimate.54 This has been explained by different writers in many different ways, as from the mothers being generally young, from the large proportion of, first preg- nancies, &c. But wo have seen that male infants, from the large size of their heads, suffer more than female infants during parturition ; and as the mothers of illegitimate children must be more liable than other women to undergo bad labours, from various causes, such as attempts at concealment by tight lacing, hard work, distress of mind, &c, their male infants would proportionably suffer. And this probably is the most efficient of all the causes of the proportion of males to females born alive being less amongst illegitimate children than amongst the legitimate. With most animals the greater size of the adult male than of the female, is due to the stronger males having conquered the weaker in their straggles for the possession of the females, and no doubt it is owing to this fact that the two sexes of at least some animals differ in size at birth. Thus 58 ' West Kiding Lunatic Asylum Paraguay, according to the accurate Reports,' vol. i. 1871, p. 8. Sir J. Azara (4 Voyages dans I'Amerique Simpson has proved that the head merid.' torn. ii. 1809, p. 60, 179), of the male infant exceeds that of the women are to the men in the the female by 3-8ths of an inch in proportion of 14 to 13. circumference, and by l-8th in 54 Babbage, * Edinburgh Journal transverse diameter. Quetelet has of Science,' 1829, vol. i. p. 88 ; also ihewn that woman is born smaller p. 90, on still-born children. Oa than man; see Dr. Duncan, 'Fe- illegitimate children in England, cundity, Fertility, Sterility,* 1871, see 'Report of Registrar-General p. 382. for 1866/ p. xv, ** With the savage Guaranys of Chap. VIII. Proportion of the Sexes. 245 we have the curious fact that we may attribute the more frequent deaths of male than female infants, especially amongst the illegitimate, at least in part to sexual selection. It has often been supposed that the relative age of the two parents determines the sex of the offspring ; and Prof. Leuckart05 has advanced what he considers sufficient evidence, with respect to man and certain domesticated animals, that this is one impor- tant though not the sole factor in the result. So again the period of impregnation relatively to the state of the female has been, thought by some to be the efficient cause ; but recent observa- tions discountenance this belief. According to Dr. Stockton- Hough,66 the season of the year, the poverty or wealth of the parents, residence in the country or o cities, the crossing of foreign immigrants, &c, all influence the proportion of the sexes. With mankind, polygamy has also been supposed to lead to the birth of a greater proportion of female infants ; but Dr. J. Campbell 67 carefully attended to this subject in the harems of Siam, and concludes that the proportion of male to female births is the same as from monogamous unions. Hardly any animal has been rendered so highly polygamous as the English race- horse, and we shall immediately see that his male and female oflspring are almost exactly equal in number. I will now give the facts which I have collected with respect to the proportional numbers of the sexes of various animals ; and will then briefly discuss how far selection has come into play in determining the result. Horses. — Mr. Tegetmeier has been so kind as to tabulate for me from the 'Racing Calendar' the births of race-horses daring a period of twenty-one years, viz., from 1846 to 1867 ; 1849 being omitted, as no returns were that year published. The total births were 25,560,58 con- sisting of 12,763 male3 and 12,797 females, or in the proportion of 99*7 males to 100 females. As these numbers are tolerably large, and as they are drawn from all parts of England, during several years, we may with much confidence conclude that with the domestic horse, or at least with the race-horse, the two sexes are produced in almost equal numbers. The fluctuations in the proportions during successive years 55 Leuckart (in Wagner 'Hand- notice, as shewing how infertile worterbuch der Phys.' L. iv, 1853, these highly-nurtured and rathex s. 774. oiosely-interbred animals have be- 86 Social Science Assoc, of Phila- come, that not far from one-third o! delphia, 1874. ^ the Diazes failed iD produce lmng " * Anthropological Rcriew/ foals. Thus during 1866, 809 male April, 1870, p. cviii. * colts nad 816 female colts were bom, 58 During eleven years a record and 743 mares failed to produce was kept of the number of mares offspring. During 1867, 836 male* which proved barren or prematurely and 902 females were born, ap4 7#4 slipped their foals ; and it observes mares failed, 246 The Descent of Man, Fabs IL 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 tabulated returns the proportions vary in cycles, for the males exceeded tho 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 Registrar's Report for 1866. Dogs. — During a period of twelve years, from 1857 to 1868, the births of a large number of greyhounds, throughout England, were sent to the * Field' newspaper ; and I am again indebted to Mr. Tegetmeier for carefully tabulating tho results. The recorded births were 6878, consisting of 3605 males and 3273 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 probably 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 enquired from several great breeders of dogs, and finds that all without exception believe that females are produced in excess ; but he suggests that this belief may have arisen from females being less valued, and from the consequent disappointment producing a stronger impression on the mind. Sheep. — The sexes of sheep are not ascertained by agriculturists until several months after birth, at the period when the males are castrated ; so that the following returns do not give the proportions at birth. Moreover, I find that several great breeders in Scotland, who annually raise some thousand sheep, are firmly convinced that a larger proportion of males than of females die during the first year or two. Therefore the proportion of males would be somewhat larger at birth than at the age of castration. This is a remarkable coincidence with what, as we have seen, occurs with mankind, and both cases probably depend on the same cause. I have received returns from four gentlemen in England ffho have bred Lowland sheep, chiefly Leicesters, during the last ten to sixteen years; they amount altogether to 8965 births, consisting of 4407 males and 4558 females; that is in the proportion of 96 7 males to 100 females. With respect to Cheviot and black-faced sheep bred in Scotland, I have received returns from six breeders, two of them on a >arge scale, chiefly for the years 1867-1869, but some of the returns extend back to 1862. The total number recorded amounts to 50,685, consisting of 25,071 males and 25,614 females, or in the proportion of 97.9 males to 100 females. If we take the English and Scotch returns together, the total number amounts to 59,650, consisting of 29,478 males and 30,172 females, or as 97*7 to 100. So that with sheep at the age of castration the females are certainly in excess of the males, but probably this would not hold good at birth.59 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- *• I am much indebted to Mr. tion to the premature deaths of the Cnpples for having procured for me males, — a statement subsequently the above returns from Scotland, as confirmed by Mr. Aitchison and well as some of the following re- others. To this latter gentleman, turns on cattle. Mr. R. Elliot, of and to Mr. Payan, I owe my thank* Laighwood, first called my atteu- for Urge returns as to sheep. Chap. VIII. Proportion of the Sexes. 247 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 has enquired from several breeders of Pigs, and most of them estimate the male to the female births as about 7 to 6. This same gentleman has bred Rabbit* for many years, and has noticed that a far greater number of bucks are produced than does. But estimations are of little value. Of mammalia in a state of nature I have been able to learn very little. In regard to the common rat, I have received conflicting statements. Mr. R. Elliot, of Laighwood, informs me that a rat-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 44 than the females ;"60 and as the catching of these animals is a special occupation, the statement may perhaps be trusted. Sir A. Smith, in describing an antelope of S. Africa61 (Kobus ellipsiprymnus), remarks, that in the herds of this and other species, the males are few in number compared with the females : the natives believe that they are born in this proportion; others believe that the younger males 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 when expelled from the herd, would often fall a prey to the many beasts of prey of the country. BIRDS. With respect to the Fowl, I have received only one account, namely, that out of 1001 chickens of a highly-bred stock of Cochins, reared during eight years by Mr. Stretch, 487 proved males and 514 females; i.e., as 94*7 to 100. In regard to domestic pigeons there is good evidence either that the males are produced in excess, or that they live longer ; for these birds invariably pair, and single males, as Mr. Teget- meier informs me, can always be purchased cheaper than females. Usually the two birds reared from the two eggs laid in the same nest are a male and a 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. With respect to birds in a state of nature, Mr. Gould and others67 are convinced that the male.* are generally the more numerous; and as the young males of many species resemble the females, the latter would naturally appear to be the more numerous. Large numbers of pheasants are reared by Mr. Baker of Leadenhall from eggs laid by wild birds, and he informs Mr. Jenner Weir that four or five males to one female are generally produced. An experienced observer remarks.63 69 Bell, ' History of British Quad- iv. s. 990) comes to the same con- rupeds/ p. 100. elusion. 91 ' Illustrations of the Zoology 63 On the authority of L. Lloyd, of S. Africa,' 1849, pi. 29. 'Game Birds of Sweden/ 1867 pp. «* Brehm (' Illiist. Thierleben/ B. 12, 132. 248 The Desce?it of Man. Part II, that in Scandinavia the broods of the capercailzie and black-cock contain more males than females ; and that with the Dal-ripa (a kind of ptarmigan) more males than females attend the leks or places of courtship : bnt this latter circumstance is accounted for by some observers by a greater number of hen birds being killed by vermin. From various facts given by White of Selborne,64 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 Scotland. Mr. Weir on enquiring from the dealers, who receive at certain seasons large numbers of ruffs (Machetes pugnax), was told that the males are much the more numerous. This same naturalist has also enquired for me from the birdcatchers, who annually catch an astonishing numbei of various small species alive for the London market, and he was un- hesitatingly answered by an old and trustworthy man, that with the chaffinch the males are in large excess; he thought as high as 2 males to 1 female, or at least as high as 5 to 3.6a The males of the blackbird. he likewise maintained, were by far the more numerous, whether caught by traps or by netting at night. These statements may apparently be trusted, because this same man said that the sexes are about equal with the lark, the twite (Linaria montana), and goldfinch. On the other hand, he is certain that with the common linnet, the females preponderate greatly, bnt 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 season 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 particular attention to the sexes of the humming-birds in Central America, and he is convinced that with most of the species the males are in excess ; thus one year he procured 204 specimens belonging to ten species, and these consisted of 166 males and of only 38 females. With two other species the females were in excess : but the proportions apparently vary either during different seasons or in different localities; for on one occasion the males of Campylopterus hemileucurus were to the females as 5 to 2, and on another occasion66 in exactly the reversed ratio. As bearing on this latter point, I may add, that Mr. Powys found in Corfu and Epirus the sexes of the chaffinch keeping apart, and " the females by far the " most numerous ;" whilst in Palestine Mr. TriBtram found " the male " flocks appearing greatly to exceed the female in number."67 So again with the Quiscalus major, Mr. G. Taylor68 says, that in Florida there were " very few females in proportion to the males," whilst in Honduras the proportion was the other way, the species there having the character of a polygamist. M * Nat. Hist, of Selborne,' letter ever caught by one man in a single xxix. edit, of 1825, vol. i. p. 139. day was 70. 65 Mr. Jenner Weir received 66 * Ibis,' vol. ii. p. 260, as quoted similar information, on making en- m Gould's * Trochilidse,' 1861, p. quiries during the following year. 52. For the foregoing proportions, To shew the number of living chaf- I am indebted to Mr. Salvin for a finches caught, I may mention that table of his results. in 1869 there was a match between 67 'Ibis,' 1860, p. 137; and 1867 two experts, and one man caught p. 369. in a day 62. and another 40, male 6S 'Ibis/ 1862, p. 137. chaffinches. The greatest number Csjap. VIII. Proportion of the Sexes. 249 FISH. With Fish the proportional numbers of the sexes can be ascertained only by catching them in the adult or nearly adult state ; and there are many difficulties in arriving at any just conclusion.69 Infertile females might readily be mistaken for males, as Dr. Giinther has remarked to me in regard to trout. With some species the males are believed to die soon after fertilising the ova. 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,70 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 this same cause to greater danger than the females. Nevertheless, in tiie few cases in which the proportional numbers have been actually observed, the males appear to be largely in excess. Thus Mr. K. Buist, the superin- tendent of the Stormontfield experiments, says that in 1865, out of 70 salmon first landed for the purpose of obtaining the ova, upwards of 60 were males. In 1867 he again " calls attention to the vast disproportion " of the males to the females. We had at the outset at least ten males " to one female." Afterwards females sufficient for obtaining ova were procured. He adds, " from the great proportion of the males, they aro "constantly fighting and tearing each other on the spawning-beds."71 This disproportion, no doubt, ean be accounted for in part, but whether wholly is doubtful, by the males ascending the rivers before the females. Mr. F. Buckland remarks in regard to trout, that "it is a " curious fact that the males preponderate very largely in number over •* the females. It invariably happens that when the first rush of fish is " made to the net, there will be at least seven or 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.7* Mr. H. Lee informs me that out of 212 trout, taken for this purpose in Lord Portsmouth's park, 150 were males and 62 females. The males of the CyprinidsB likewise seem to be in excess ; but several members of this Family, viz., the carp, tench, bream and minnow, appear regularly to follow the practice, rare in the animal kingdom, of polyandry; far the female whilst spawning is always attended by two males, one on each side, and in the case of the bream by three or four males. This fact is so well known, that it is always recommended to stock a pond with two male tenches to one female, or at least with three males to two females. With the minnow, an excellent observer states, that on the spawning-beds the males are ten times as numerous as the females; when a female comes amongst the 49 Leuckart quotes Bloch (Wag- 18, 1869, p. 369. aer, < Handworterbuch der Phys.' • 1 * The Stormontfield Piscicnl- B. iv. 1853, s. 775), that with fish tural Experiments/ 1866, p. 23, there are twice as many males as The * Field ' newspaper, June 29tn, 1867. 10 Quoted in the 'Farmer,' March n « Land and Water/ 1868, p. 41 250 The Descent of Man. Part TL males, i{ 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." n INSECTS. In this great Class, the Lepidoptera almost alone afford means for judging of the proportional numbers of the sexes ; for they have been collected with special care by many good observers, and have been largely bred from the egg or caterpillar state. I had hoped that some breeders of silk-moths might have kept an exact record, but after writing to France and Italy, and consulting various treatises, I cannot lind that this has ever been done. The general opinion appears to be that the sexes are nearly equal, but in Italy, as I hear from Professor Canestrini, many breeders are convinced that the females are produced in excess. This same naturalist, however, informs me, that in the two yearly broods of the Ailanthus silk-moth (Bombyx cynfhia), the males greatly preponderate in the first, whilst in the second the two sexes are nearly equal, or the females rather in excess. In regard to Butterflies in a state of nature, several observers have been much struck by the apparently enormous preponderance of the males.74 Thus Mr. Bates,75 in speaking of several species, about a hundred in number, which inhabit the Upper Amazons, says that the males are much more numerous than the females, even in the propor- tion of a hundred to one. In North America, Edwards, who had great experience, estimates in the genus Papilio the males to the females as four to one ; and Mr. Walsh, who informed me of this statement, says that with P. turnm this is certainly the case. In South Africa, Mr. R. Trimen found the males in excess in 19 species ;76 and in one of these, which swarms in opvn places, he estimated the number of males as fifty to one female. With another species, in which the males are numerous in certain localities, he collected only five females during seven years. In the island of Bourbon, M. Maillard states that the males of one species of Papilio are twenty times as numerous as the females.77 Mr. Trimen informs me that as far as he has himself seen, or heard from others, it is rare for the females of any butterfly to exceed the males in number; but three South African species per- haps offer an exception. Mr. Wallace 78 states that the females of Ornithoptera crossus, in the Malay archipelago, are more common and more easily caught than the males ; but this is a rare butterfly. I may 73 Yarrell, * Hist. British Fishes,' or four times as numerous as the irol. i. 1826, p. 307 ; on the Cyprinus females. carpio, p. 331 ; on the Tinea vulgaris, 7S * The Naturalist on the Ama- p. 331 ; on the Abramis brama, p. zons,' vol. ii. 1863, p. 228, 347- 336. See, for the minnow {Leu- 7e Four of these cases are given ciscus phoxinus), i Loudon's Mag. of by Mr. Trimen in his i Rhopaloeera Nat. Hist.' vol. v. 1832, p. 682. Africa? Australis/ 74 Leuckart quotes Meinecke " Quoted by Trimen, c Transact. (Wagner, * Handworterbuch der Ent. Soc/ vol. v. part iv. 1866, p. 330, Phys.' B. it. 1853, s. 775) that 78 'Transact. Linn. Soc,' vol, xxv. the males of Butterflies are three p. 37. Chap. VIII. Proportion of the Sexes. 25 1 bete add, that in Hyperythra, a genus of moths, Guenee says, that from four to five females are sent in collections from India for one male. When this subject of the proportional numbers of the sexes of insects was brought before the Entomological Society,79 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 Bombyx Yamamai, are useless at the begin- ning of the season, and the females at the end, from the want of mates.80 I cannot, however, persuade myself that these causes suffice to explain the great excess of males, in the above cases of certain butter- flies which axe extremely common in their native countries. Mr. Stainton, who has paid very close attention during many years to the smaller moths, informs me that when he collected them in the imago state, he thought that the males were ten times as numerous as the females, but that since he has reared them on a large scale from the caterpillar state, he is convinced that the females are the more numerous. Several entomologists concur in this view. Mr. Double- day, however, and some others, take an opposite view, and are con- vinced that they have* reared from the eggs and caterpillars a larger proportion of males than of females. Besides the more active habits of the males, their earlier emergence from the cocoon, and in some cases their frequenting more open stations, other causes may be assigned for an apparent or real difference in the proportional numbers of the sexes of Lepidoptera, when cap- tured in the imago state, and when reared from the egg or caterpillar Btate. I hear from Professor Canestrini, that it is believed by many breeders in Italy, that the female caterpillar of the silk-moth suffers more from the recent disease than the male ; and Dr. Staudinger informs me that in rearing Lepidoptera more females die in the cocoon than males. With many species the female caterpillar is larger than the male, and a collector would naturally choose the finest specimens, and thus unintentionally collect a larger number of females. Three collectors have told me that this was their practice ; but Dr. Wallace is sure that most collectors take all the specimens which they can find of the rarer kinds, which alone are worth the trouble of rearing. Birds when surrounded by caterpillars would probably devour the largest ; and Professor Canestrini informs me that in Italy some breeders believe, though on insuificient evidence, that in the first broods of the Ailanthus silk-moth, the wasps destroy a larger number of the female than of the male caterpillars. Dr. Wallace further remarks that female caterpillars, from being larger than the males, require more time for their development, and consume more food and mois ture ; and thus they would be exposed during a longer time to danger from ichneumons, birds, &c, and in times of scarcity would perish in greater numbers. Hence it appears quite possible thai 79 ' Proc. Entomolog. Soc* Feb. 'Proc. Ent. Soc* 3rd sciieg, ▼©!, v I7th, 1868. l8tJ7?l.487. 8C Quoted by Dr. Wallace in 252 The Descent of Man. Pam n. in a state of nature, fewer female Lepidoptera may reach, maturity than males ; and for our special object we are concerned with their relative 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 indicates 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 in confinement. In the Isle of Wight Mr. Trimen exposed a box in which a female of the Lasiocampa hud been confined on the previous day, and five males soon endeavoured to gain admittance. In Australia, M. Verreaux, having placed the female of a small Bombyx in a box in his pocket, was followed by a crowd of males, so that about 200 entered the house with him.81 Mr. Doubleday has called my attention to M. Staudinger's 82 list of Lepidoptera, which gives the prices of the males and females of 300 species or well-marked varieties of butterflies^Rhopalocera). The prices for both sexes of the very common species are of course the same ; but in 114 of the rarer species they differ; the males being in all cases, excepting one, the cheaper. On an average of the prices of the 113 species, the price of the male to that of the female is as 100 to 149 ; and this apparently indicates that inversely the maks exceed the females in the same proportion. About 2000 species or varieties of moths (Heterocera) are catalogued, those with wingless females being here excluded on account of the difference in habits between the two sexes : of these 2000 species, 141 differ in price according to sex, the males of 130 being cheaper, and those 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 accounted for only by an excess in the number of the males. But I am bound to add that Dr. Staudinger informs me, that he is himself 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 whilst confined 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 •* Blanchard, ' Metamorphoses, 82 < Lepidopteren - Doublet^ MoEurs 4es Insect^,' 1368, pp, 2 .5- Lisfe/ Berlin, No. x. 18§§, 226 CiiAf. vul Proportion of the Sexes. m from eggs or caterpillars, I have received only the few following cases : — Males. | Females- The fiev. J. Hellins83 of Exeter reared, during 1868,1! imagos of 73 species, which consisted of. . . J Mr. Albert Jones of Eltham reared, during 1868,^1 imagos of 9 species, which consisted of . . . J During 1869 he reared imagos from 4 species, con-} sisting of . J Mr. Buckler of Emsworth, Hants, during 1869,} reared imagos from 74 species, consisting of. . / Dr. Wallace of Colchester reared from one brood of Bombyx cynthia Dr. Wallace raised, from cocoons of Bombyx PernyH sent from China, during 1869 / Dr. Wallace raised, during 1868 and 1869, from two\ lots of cocoons of Bombyx yama-mai . . . / Total 153 137 159 126 114 112 180 169 52 48 224 123 52 46 934 761 So that in these eight lots of cocoons and eggs, males were produced in excess. Taken together the proportion of males is as 122*7 to 100 females. But the numbers are hardly large enough to be trustworthy. On the whole, from these various sources of evidence, all pointing in the same direction, I infer that with most species of Lepidoptera the mature males 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 oeen able to collect very little reliable information. With the stag-beetle (Lucanus 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 Elateridse, the males are said to be much more numerous than the females, and ** two or three are often found united with one female ;84 ** so that here polyandry seems to prevail." Writh Siagonium (Staphy- linidse), in which the males are furnished with horns, " the females are 44 far more numerous than the opposite sex." Mr. Janson stated at the Entomological Society that the females of the bark- feeding Tomicus viUosus are so common as to be a plague, whilst the males are so rare us to be hardly known. 83 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 fcund it impossible % tabulate them. 84 Giinther's * Record of Zoo- logical Literature,' 1867, p. 260. On the excess of female Lucanus, ibid.«p. 250. On the males of Luca- nus in England, Westwood, * Modern Class, of insects/ vol. i. p. 187. On the Siagonium, ibid. p. 172. 254 *£}& Descent of Man. Par*! if. It is hardly worth While saying anything about the proportion of the sexes in certain species and even groups of insects, for the inah\» are unknown or very rare, and the females are parthenogenetic, thar is, fertile without sexual union; examples of this are afforded by several of the Cynipidee.85 In ail the gall-making Cynipidse known to Mr. Walsh, the females are four or live times as numerous as the males ; and so it is, as he informs me, with the gall-making Cecidomyiiae (Diptera). With some common species of Saw-flies (Tenthredinse) 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,86 that with certain species (Athalia), bred by him, the males were to the females as six to one ; whilst exactly the reverse occurred with the mature insects of the same species caught in the fields. In the family of Bees, Hermann Miiller,87 collected a large number of specimens of many species, and reared others from the cocoons, and counted the sexes. He found that the males of some species greatly exceeded the females in number ; in others the reverse occurred ; and in others the two sexes were nearly equal. But as in most cases the males emerge from the cocoons before the females, they are at the commencement of the breeding season practically in excess. Miiller also observed that the relative number of the two sexes in some species differed much in different localities. But as H. Miiller has himself remarked to me, these remarks must be received with some caution, as one sex might more easily escape observation than the other. Thus his brother Fritz Miiller has noticed in Brazil that the two sexes of the same species of bee sometimes frequent different kinds of flowers. With respect to the Orthoptera, I know hardly anything about the relative number of the sexes : Korte,88 however, says that out of 500 locusts which he examined, the males were to the females as five to six. With the Neuroptera, Mr. Walsh states that in many, but by no means in all the species of the Odonatous group, there is a great overplus of males : in the genus Hetaerina, 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 in excess, whilst 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, whilst w4th other species of the same genus both sexes are common.89 In England, Mr. MacLachlan 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 seen here.90 With most of these species (excepting the Tenthredinae) there is at present no evidence that the females are subject to parthenogenesis ; and thus we see how ignorant we are of the causes of the apparent discrepancy in the proportion of the two sexes. In the other Classes of the Articulata I have been able to collect still M Walsh, in * The American En- derheuschrecke,' 1828, p. 20. tomologist,' vol. i. 1869, p. 103. 8B * Observations on N. American F. Smith, * Record of Zoological Neuroptera/ by H. Hagen and B. D. Literature/ 1867, p. 328. Walsh, < Proc. Ent. Soc. Phila- 86 * Farm Insects,' pp. 45-46. delphia,' Oct. 1863, pp. 168, 223, *7 * Anwendung der Darwinschen 239. I^hre Verh. d. n. V. Jahrej. xxiv.* 9* lckenaer et P. Gexvais, Class, of Insects,* vol. ii. p. 213. Chap. X. Insects. 275 Mutillidae; and here the females are likewise wingless. Brit we are chiefly concerned with structures by which one male is enabled to conquer another, either in battle or courtship, through his strength, pugnacity, ornaments, or music. The innumerable contrivances, therefore, by which the male is able to seize the female, may be briefly passed over. Besides the complex structures at the apex of the abdomen, which ought perhaps to be ranked as primary organs,2 "it is astonishing," as Mr. B. D. Walsh3 has remarked, " how many different organs are worked in by nature " for the seemingly insignificant object of enabling the male to . " grasp the female firmly." The mandibles or jaws are some- times used for this purpose ; thus the male Corydalis comutus (a neuropterous insect in some degree allied to the Dragon-flies, &c.) has immense curved jaws, many times longer than those of the female ; and they are smooth instead of being toothed, so that . he is thus enabled to seize her without injury.4 One of the stag-beetles of North America (Lucanus elaphus) uses his jaws, which are much larger than those of the female, for the same purpose, but probably likewise for fighting. In one of the sand-wasps (Ammophila) the jaws in the two sexes are closely alike, but are used for widely different purposes : the males, as Professor Westwood observes, " are exceedingly ardent, seizing " their partners round the neck with their sickle-shaped jaws;"5 whilst the females use these organs for burrowing in sand-banks and making their nests. The tarsi of the front-legs are dilated in many male beetles, or are furnished with broad cushions of hairs ; and in many genera of water-beetles they are armed with a round flat sucker, so that the male may adhere to the slippery body of the female. It is a 2 These organs in the male often species having been observed in differ in closely-allied species, and union. Mr. MacLachlan informs afford excellent specific characters, me (vide ' Stett. Ent. Zeitung,* But their importance, from a func- 1867, s. 155) that when several tional point of view, as Mr.' R. species of Phryganidae, which pre- MacLachlan has remarked to me, sent strongly-pronounced differences has probably been overrated. It of this kind, were confined together nas been suggested, that slight dif- by Dr. Aug. Meyer, they coupled, -ferences in these organs woulcf and one pair produced fertile oVa. suffice to prevent the intercrossing * ' The Practical Entomologist,* of well-marked varieties or incipient Philadelphia, vol. ii. May, 1867, species, and would thus aid in their p. 88. development. That this can hardly * Mr. Walsh, ibid. p. 107. be the case, we may infer from the * 'Modern classification of In- many recorded cases (see, for in- sects,' vol. ii. 1840, pp. 205, 206. instance, Bronn, ' Geschichte der Mr. Walsh, who called my attention Xatur,' B. ii. 1843, s. 164; and to the double use of the jaws, say* Westwood, * Transact. Ent. Soc' that he has repeatedly observed} toL iii. 1842, p. 195) of distinct this fact. T 2 2^6 The Descent of Man. Pabt II. much more unusual circumstance that the female of some water- beetles (Dytiscus) have their elytra deeply grooved, and in Acilius sulcatus thickly set with hairs, as an aid to the male. The females of some other water- beetles (Hydroporus) have their elytra punctured for the same purpose.6 In the male of Crabro cribrarius (fig. 9), it is the tibia which is dilated into a broad horny plate, with minute mem- braneous dots, giving to it a sin- gular appearance like that of a riddle.7 In the male of Penthe (a genus of beetles) a few of the middle joints of the antennae are dilated and furnished on the in- ferior surface with cushions of hair, exactly like those on the tarsi of the Carabidse, " and obviously for " the same end." In male dragon- flies, "the appendages at the tip " of the tail are modified in an " almost infinite variety of curious (i patterns to enable them to em- " brace the neck of the female." Lastly, in the males of many in- sects, the legs are furnished with peculiar spines, knobs or spurs ; or the whole leg is bowed or thickened, but this is by no means invariably a sexual character ; or one pair, or all three pairs are elongated, sometimes to an extravagant length.8 The sexes of many species in all the orders present differences, of which the meaning is not understood. One curious case is that of a beetle (fig. 10), the male of which has the left mandible much enlarged; bo that the mouth is greatly distorted. In another Carabidous beetle, Eurygnathus,9 we have the case, 6 We have here a curious and * Introduction to Entomology,' vol. inexplicable case of dimorphism, for iii. 1826, p. 305. Fig. 9. Crabro cribrarius. Upper figure, male; lower figure, female. some of the females of four Euro- pean species of Dytiscus, and of certain species of Hydroporus, have their elytra smooth ; and no inter- mediate gradations between the sulcated or punctured, and the quite smooth elytra have been observed. See Dr. H. Schaum, as quoted in the * Zoologist/ vol. v.-vi. 1847-48, p. 1896. Also Kirby and Spcnce, Westwood, 'Modern Class.' vol. ii. p. 193. The following state- ment about Penthe, and others in inverted commas, are taken from Mr. Walsh, * Practical Entomolo- gist,' Philadelphia, vol. ii. p. 88. 8 Kirby and Spence, ' Introduct.' &c, vol. iii. pp. 332-336. a * Insecta Maderensia/ 1854} p. 20. Chap. X. Insects. w unique 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 extra- ordinary is that certain male butterflies have their fore-legs more or less atrophied, with the tibiae and tarsi reduced to mere ru- dimentary knobs. The wings, also, in the two sexes often differ in neuration,10 and some- times considerably in outline, as in the Ari- coris epitus, which was shewn to me in the British Museum by Mr. A. Butler. The males of certain South American butterflies have tufts of hair on the margins of the wings, and horny excrescences on the discs of the posterior pair.11 In several British butter- flies, as shewn by Mr. Wonfor, the males alone are in parts clothed with peculiar scales. The use of the bright light of the female glow-worm has been subject to much discus- sion. The male is feebly luminous, as are the larvae and even the eggs. It has been sup- posed by some authors that the light serves to frighten away enemies, and by others to guide the male to the female. At last, Mr. Belt12 appears to have solved the difficulty: he finds that all the Lampyridse which he has tried are highly distasteful to insectivorous mammals and birds. Hence it is in accordance with Mr. Bates' view, hereafter to be explained, that many insects mimic the Lampyridse closely, in order to be mistaken for them, and thus to escape destruction. He further be- lieves that the luminous species profit by being at once recognised as unpalatable. It is probable that the same explanation may be extended to the 74. Mr. Wonfor's observations are quoted in * Popular Science Eeview,' 1868, p. 343. 12 ' The Naturalist in Nicaragua? 1874, pp. 316-320. On the phos- phorescence of the eggs, see * Annals and Mag. of Nat. Hist/ 1871/ Nov., p. 372. Fig. 10. Taphroderes distortus (much en- larged). Upper fig- ure, male ; lower figure, female. 10 E. Douhleday, ' Annals and Mag. of Nat. Hist/ vol. i. 1848, p. 379. I may add that the wings in certain Hymenoptera (see Shuckard, * Fossorial Hymenop/ 1837, pp. 39- 43) differ in neuration according to sex. 11 H. W. Bates, jl Journal of Froc. Linn. Soc/ vol. vi. 1862, p. 278 The Descent of Man. Part U. Elates, both sexes of which are highly luminous. It is not known why the wings of the female glow-worm have not been developed ; but in her present state she closely resembles a larva, and as larvae are so largely preyed on by many animals, we can understand why she has been rendered so much more luminous and conspicuous than the male ; and why the larvae themselves are likewise luminous. Difference in Size between the Sexes. — -With insects of all kinds the males are commonly smaller than the females; and this difference can often be detected even in the larval state. So considerable is the difference between the male and female cocoons of the silk-moth (Bombyx mori), that in France they are separated by a particular mode of weighing.18 In the lower classes of the animal kingdom, the greater size of the females seems generally to depend on their developing an enormous number of ova ; and this may to a certain extent hold good with insects. But Dr. Wallace has suggested a much more probable explanation. He finds, after carefully attending to the develop- ment of the caterpillars of Bombyx cynthia and yama?nai, and especially to that of some dwarfed caterpillars reared from a second brood on unnatural food, " that in proportion as the in- " dividual moth is finer, so is the time required for its metamor- phosis 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." H Now as most insects are short-lived, and as they are exposed to many dangers, it would manifestly be ad- vantageous to the female to be impregnated as soon as possible. This end would be gained by the males being first matured in large numbers ready for the advent of the females ; and this again would naturally follow, as Mr. A. B. "Wallace has re- marked,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, whilst tho larger males from being matured later would leave fewer offspring. There are, however, exceptions to the rule of male insects being smaller than the females : and some of these exceptions are intelligible. Size and strength would be an advantage to the males, which fight for the possession of the females; and in these cases, as with the stag-beetle (Lucanus), the males are larger than the females. There are, however, other beetles 13 RoMnet, 'Vers k Soie/ 1848, vol. v. p. 486. ^ 207. is 'Journal of Proc. Ent. Sco M ' Transact. Ent. Soc.' 3rd series, Feb. 4th, 1867, p. lxxi. Chap. X. Thysanura. 279 winch are not known to fight together, of which the males exceed the females in size; and the meaning of this fact is not known; but in some of these cases, as with the huge Dynastes and Megasoma, we can at least see that there would be no necessity for the males to be smaller than the females, in order to be matured before them, for these beetles are not short-lived, and there would be ample time for the pairing of the sexes. So again, male dragon-flies (Libellulidse) are sometimes sensibly larger, and never smaller, than the females;16 and as Mr. MacLachlan believes, they do not generally pair with the females until a week or fortnight has elapsed, and until they have assumed their proper masculine colours. But the most curious case, shewing on what complex and easily-overlooked relations, so trifling a character as difference in size between the sexes may depend, is that of the aculeate Hymenoptera ; for Mr. F. Smith informs me that throughout nearly the whole of this large group, the males, in accordance with the general rule, are smaller than the females, and emerge about a week before them ; but amongst the Bees, the males of Apis mellifica, Anthidium manicatum, and Antkoplwra acervorum, and amongst the Fossores, the males of the Methoca ichneumonides, are larger than the females. The explanation of this anomaly is that a marriage flight is absolutely necessary with these species, and the male requires great strength and size in order to carry the female through the air. Increased size has here been acquired in op- position to the usual relation between size and the period of development, for the males, though larger, emerge before the smaller females. We will now review the several Orders, selecting such facts as more particularly concern us. The Lepidoptera (Butterflies and Moths) will be retained for a separate chapter. • Order, Thysanura. — The members of this lowly organized order are wingless, dull-coloured, minute insects, with ugly, almost misshapen heads and bodies. Their sexes do not differ but they are interesting as shewing us that the males pay sedulous court to the females even low down in the animal scale. Sir J. Lubbock n says : " it is very amusing to see these " little creatures (Smynthurus luteus) coquetting together. The " male, which is much smaller than the female, runs round her, " and they butt one another, standing face to face and moving 11 For this and other statements see p. 344. on the size of the sexes, see Kirby 17 * Transact. Linnean Sofc* tf§L and Spence, ibid. vol. iii. p. 300 ; xxvj. 1868, p. 29$. on the duration of life in insects, sSo The Descent of Man. Part IL * backward and forward like two playful lambs. Then ths " female pretends to run away and the male runs after her with " a queer appearance of anger, gets in front and stands facing " her again ; then she turns coyly round, but he, quicker and " more active, scuttles round too, and seems to whip her " with his antennae ; then for a bit they stand face to face, " play with their antennas, and seem to be all in all to one " another." Order, Diptera (Flies). — The sexes differ little in colour. The greatest difference, known to Mr. F. Walker, is in the genus Bibio, in which the males are blackish or quite black, and the females obscure brownish-orange. The genus Elaphomyia, dis- covered by Mr. Wallace 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 a stag, being either branched or pal- mated. In one of the species, they equal the whole body in length. They might be thought to be adapted for fighting, but as in one species they are of a beautiful pink colour, edged with black, with a pale central stripe, and as these insects have altogether a very elegant appearance, it is perhaps more probable that they serve as ornaments. That the males of some Diptera fight together is certain ; for Prof. Westwood 19 has several times seen this with the Tipulse. The males of other Diptera ap- parently try to win the females by their music : H. Miiller * watched for some time two males of an Eristalis courting a female; they hovered above her, and flew from side to side, making a high humming noise at the same time. Gnats and mosquitoes (Culicidae) also seem to attract each other by hum- ming ; and Prof. Mayer has recently ascertained that the hairs On the antennas of the male vibrate in unison with the notes of a tuning-fork, within the range of the sounds emitted by the female. The longer hairs vibrate sympathetically with the graver notes, and the shorter hairs with the higher ones. Landois also asserts that he has repeatedly drawn down a whole swarm of gnats by uttering a particular note. It may be added that the mental faculties of the Diptera are probably higher than in most other in- sects, in accordance with their highly developed nervous system.21 18 * The Malay Archipelago/ vol. 21 See Mr. B. T. Lowne's interest- ii. 1869, p. 313. . ing work, * On the Anatomy of the 19 4 Modern Classification of In- Blow-fly, Musca vomitoria/ 1870, p. sects/ vol. ii. 1840, p. 526. 14. He remarks (p. 33) that, " the 20 Anwendung, &c, * Verh. d. n. " captured flies utter a peculiar V. Jahrg.' xxix. p. 80. Mayer, in " plaintive note, and that this sountf ' American Naturalist/ 1874, p. 236. " causes other flies to disappear." Chap. X, Hemiptera and Homoptera, 281 Order, Hemiptera (Field-Bugs).— Mr. J. W. Douglas, who has particularly attended to the British species, has kindly given me an account of their sexual differences. The males of some species are furnished with wings, whilst the females are wingless ; tha sexes differ in the form of their bodies, elytra, antennae and tarsi ; but as the signification of these differences are unknown, they may be here passed over. The females are generally larger and more robust than the males. With British, and, as far as Mr. Douglas knows, with exotic species, the sexes do not commonly differ much in colour; but in about six British species the male is considerably darker than the female, and in about four other species the female is darker than the male. Both sexes of some species are beautifully coloured; and as these insects emit an extremely nauseous odour, their con- spicuous colours may serve as a signal that they are unpalat- able to insectivorous animals. In some few cases their colours appear to be directly protective : thus Prof. Hoffmann informs me that he could hardly distinguish a small pink and green species from the buds on the trunks of lime-trees, which this insect frequents. Some species of Reduvidae make a stridulating noise ; and, in the case of Pirates stridulus, this is said 22 to be effected by the movement of the neck within the pro-thoracic cavity. Accord- ing to Westring, Eeduvius personatus also stridulates. But I have no reason to suppose that this is a sexual character, ex- cepting that with non-social insects there seems to be no use for sound-producing organs, unless it be as a sexual call. Order, Eomoptera. — Every one who has wandered in a tropi- cal forest must have been astonished at the din made by the male Cicada. The females are mute; as the Grecian poet Xenarchus says, " Happy the Cicadas live, since they all have " voiceless wives." The noise thus made could be plainly heard on board the " Beagle," when anchored at a quarter of a 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.28 The Cicadidsa usually sing during the day, whilst the Fulgorid® appear to be night-songsters. The sound, according to Landois,2* 22 Westwood, ' Modern Class, of also, on the Fulgoridae, Kirby and Insects,' vol. ii. p. 473. Spence, ' Introduct.' vol. ii. p. 401. i3 These particulars are taken 24 'Zeitschrift fdr wiss^nschaft from Westwood's * Modern Class, of Zoolog.' B, xvii, 1867, 8. 152-158, Insects,' toL ii 1840, p. 422. See, 282 The Descent of Man. Paet H, is produced by the vibration ot the lips of the spiracles, which are set into motion by a current of air emitted from the tracheae ; but this view has lately been disputed. Dr. Powell appears to have proved M that it is produced by the vibration of a mem- brane, set into action by a special muscle. In the living insect, whilst stridulating, this membrane can be seen to vibrate ; and in the dead insect the proper sound is heard, if the muscle, when a little dried and hardened, is pulled with the point of a pin. In the female the whole complex musical apparatus is present, but is much less developed than in the male, and is never used for producing sound. With respect to the object of the music, Dr. Hartman, in speaking of the Cicada septemdecim of the United States, says, 2S " the drums are now (June 6th and 7th, 1851) heard in all " directions. This I believe to be the marital summons from " the males. Standing in thick chestnut sprouts about as high " as my head, where hundreds were around me, I observed the " females ooming around the drumming males." He adds, " this " season (Aug. 1868) a dwarf pear-tree in my garden produced " about fifty larvae of Cic. pruinosa ; and I several times noticed " the females to alight near a male while he was uttering his " clanging notes." Fritz Miiller writes to me from S. Brazil that he has often listened to a musical contest between two or three males of a species with a particularly loud voice, seated at a considerable distance from each other : as soon as one had finished his song, another immediately began, and then another. As there is so much rivalry between the males, it is probable that the females not only find them by their sounds, but that, like female birds, they are excited or allured by the male with the most attractive voice. I have not heard of any well-marked cases of ornamental differences between the sexes of the Homoptera. Mr. Douglas informs me that there are three British species, in which the male is black or marked with black bands, whilst the females are pale-coloured or obscure. Order, Orthoptera (Crickets and Grasshoppers). — The males in the three saltatorial families in this Order are remarkable for tttelr ^wisical powers, namely the Achetidso or crickets, the LocustidaB for which there is no equivalent English name, and the Acridiidso or grasshoppers. The stridulation produced by some ,a 'Transact. New Zealand In- from a * Journal of the Doings of sutnte,' vol. v. 1873, p. 286. Cicada septemdecim ' by Dr. Hart- 36 I am indebted to Mr. Walsh man. for having sent me this extract Ghap. X. Orthoptera. 283 of the Locustidss is so loud that it can be heard during the night at the distance of a mile;27 and that made by certain species is not unmusical even to the human ear, so that the Indians on the Amazons keep them in wicker cages. All observers agree that the sounds serve either to call or excite the mute females. "With respect to the migratory locusts of Russia, K6rte has given 28 an interesting case of selection by the female of a male. The males of this species (Pachytylus migratorius) whilst coupled with the female stridulate from anger or jealousy, if approached by other males. The house-cricket when surprised at night uses its voice to warn its fellows.29 In North America the Katy-did (Platy- phyllum concavmn, one ©f the Locustidse) is described30 as mount- ing on the upper branches of a tree, and in the evening beginning " his noisy babble, while rival notes issue from the neighbouring " trees, and the groves resound with the call of Katy-did-she-did " the live-long night." Mr. Bates, in speaking of the Euro- pean field-cricket (one of the Achetidse), says, " the male has " been observed to place him- " self in the evening at the " entrance of his burrow, and " stridulate until a female ap- " proaches, when the louder " notes are succeeded by a " more subdued tone, whilst " the successful musician ca- " resses with his antennae the " mate he has won."31 Dr. Scudder was able to excite one of these insects to answer him, by rubbing on a file with a quill.32 In both sexes a re- markable auditory apparatus has been discovered by Von Siebold, situated in the front legs.K Fig. 11. Gryllus campestris (from Landois)* Right-hand figure, under side of part of a wing-nervure, much magnified, showing the teeth, st. Left-hand figure, upper surface of wing- cover, with the projecting, smooth nervure, r, across which the teeth (sf) are scraped. 27 L. Guilding, 'Transact Linn. Soc.' vol. xv. p. 154. 28 I state this on the authority of Koppen, ' Ueber die Heuschrecken in Siidrussland,' 1866, p. 32, for I have in vain endeavoured to procure Korte's work. 29 Gilbert White, 'Nat. Hist, of Selborne,' vol. ii. 1825, p. 262. 30 Harris, 'Insects of New Eng- land,' 1842, p. 128. , 3l 'The Naturalist on the Ama- zons,' vol. i. 1863, p. 252. Mr. Bates gives a very interesting dis- cussion on the gradations in the musical apparatus of the three families. See also Westwood, 'Modern Class.' vol. ii. pp. 445 and 453. 32 ' Proc. Boston Soc. of Nat, Hist.' vol. xi. April, 1868. 33 ' Nouveau Manuel d'Anatr Comp.' fFrench translat.), torn, i 1850, p/567. 284 The Descent of Man. Part IL In the three Families the sounds are differently produced. In the males of the Achetidse both wing-covers have the same apparatus; and this in the field-cricket (Gryllus campestris, fig. 11) consists, as described by Landois,34 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 ner- vure (r) on the upper surface of the opposite wing. First one wing is rubbed over the other, and then the movement is reversed. Both wings are raised a little at the same time, so as to increase the resonance. In some species the wing-covers of the males are furnished at the base with a talc-like plate.35 I here give a drawing (fig. 12) of the teeth on the under side of the nervure of another Fig. 12. Teeth of Ner- species of Gryllus, viz., 0. domesticus. With Sr(fromUi^Dd0o?sr respect to the formation of these teeth, Dr. Gruber has shewn36 that they have been de- veloped by the aid of selection, from the minute scales and hairs with which the wings and body are covered, and I came to the same conclusion with respect to those of the Coleoptera. But Dr. Gruber further shews that their- development is in part directly due to the stimulus from the friction of one wing over the other. In the Locustidse the opposite wing-covers differ from each other in structure (fig. 13), and the action cannot, as in the last family, be reversed. The left wing, which acts as the bow, lies over the right wing which serves as the fiddle. One of the nervures (a) on the under surface of the former is finely serrated, and is scraped across the prominent nervures on the upper surface of the opposite or right wing. In our British 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 thickened, coloured brown, and very sharp. In the right wing, but not in the left, there is a little plate, as transparent as talc, surrounded by nervures, and called the speculum. In 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 34 'Zeitschrift fiir wissenschaft. 36 'Ueber der Tonapparat der Zoolog/ B. xvii. 1867, s. 117. Locustiden, em Beitrag zum Dar- 35 Westwood, * Modern Class, of winismus,' 'Zeitsch. fur wissensch. Insects/ vol. i. p. 440. Zoolog.' B. xxii. 1872, p. 100. Chap. X Orthoptera. 285 '* of dome over the wing-covers, and which has probably the " effect of increasing the sound." 37 Fig. 13. Chlorocoelus Tanana (from Bates), a, b. Lobes of opposite wing-covers. We thus see that the musical apparatus is more differentiated or specialised in the Locustidse (which include, I believe, the most powerful performers in the Order), than in the Achetidse, in which both wing-covers have the same structure and the same function.58 Landois, however, detected in one of the Locustidse, namely in Decticus, a short and narrow row of small teeth, mere rudiments, on the inferior surface of the right wing- cover, which underlies the other and is never used as the bow, I observed the same rudimentary structure on the under side of the right wing-cover in Phasgonura viridissima. Hence we may infer with confidence that the Locustidse are descended from a form, in which, as in the existing Achetidse, both wing-covers had serrated nervures on the under surface, and could be /indifferently used as the bow; but that in the Locustidse the two wing-covers gradually became differentiated and perfected* 37 Westwood, * Modern Class, of Insects,* vol. i. p. 453. 58 landois, * Zeitsch. f. wiss. Zoolog.' B. xvii. 1867, s. 121, 122, 286 The Descent of Man. Paet IL on the principle of the division of labour, the one to act ex- clusively as the bow, and the other as the fiddle. Dr. Gruber takes the same view, and has shewn that rudimentary teeth are commonly found on the inferior surface of the right wing. By what steps the more simple apparatus in the Achetidse originated, we do not know, but it is probable that the basal portions of the wing-covers originally overlapped each other as they do at present; and that the friction of the nervures produced a grating sound, as is now the case with the wing-covers of the females.39 A grating sound thus occasionally and accidentally made by the males, if it served them ever so little as a love-call to the females, might readily have been intensified through sexual selection, by variations in the roughness of the nervures having been continually preserved. In the last and third Family, namely the AcridiidaB or grasshoppers, the stridulation, is produced in a very different manner, and according to Dr. Scudder, is not so shrill as in the preceding Families. The inner surface of the femur (fig. 14, r) is furnished with a longitudinal row of minute, elegant, lancet- shaped, elastic teeth, from 85 to 93 in number ;40 and these are scraped across the sharp, projecting nervures on the wing-covers, which are thus made to vibrate and resound. Harris41 says that when one of the males begins to play, he first " bends " the shank of the hind-leg " beneath the thigh, where it " is lodged in a furrow de- " signed to receive it, and " then draws the leg briskly " up and down. He does not fl play both fiddles together, " but alternately, first upon " one and then on the other." In many species, the base of the abdomen is hollowed out into a great cavity which is believed to act as a re- sounding board. In Pneu- mora (fig. 15), a S. African, genus belonging to the same family, we meet with a new Fig. 14. Hind-leg of Stenobothrus pratorum : r, the stridulating ridge ; lower figure, the teeth forming the ridge, much magnified (from Landois). 39 Mr. Walsh also informs me that he has noticed that the female of the Platyphyllum concavum, "when captured makes a feeble "grating noise by shuffling her " wing-covers together." 40 Landois, ibid. s. 113. 41 * Insects of New England,* 1842, p. 133. Chap. X Ofthopierfo 2%J and remarkable modification; in the males a small notched ridge projects obliquely from each side of the abdomen, against which the hind femora are rubbed.42 As the male is furnished with wings (the female being wingless), it is re- markable that the thighs are not rubbed in the usual manner against the wing-covers ; but this may perhaps be accounted for by the unusually small size of the hind-legs. I have not been able to examine the inner surface of the thighs, which, judging Fig. 15. Pneumora (from specimens in the British Museum). Upper figure, male lower figure, female. from analogy, would be finely serrated. The species of Pneumora have been more profoundly modified for the sake of stridulation than any other orthopterous insect; for in the male the whole body has been converted into a musical instrument, being 42-Westwood4 ' Modern Classification,' vol. i. p. 462. 2 88 TJw Descent of Man. Past IL distended with air, like a great pellucid bladder, so as to increase the resonance. Mr. Trimen informs me that at the Cape of Good Hope these insects make a wonderful noise during the night. In the three foregoing families, the females are almost always destitute of an efficient musical apparatus. But there are a few exceptions to this rule, for Dr. Gruber has shewn that both sexes of Epkippiger vitium are thus provided; though the organs differ in the male and female to a certain extent. Hence we cannot suppose that they have been transferred from the male to the female, as appears to have been the case with the secondary sexual characters of many other animals. They must have been independently developed in the two sexes, which no doubt mutually call to each other during the season of love. In most other Locustidse (but not according to Landois in Decticus) the females have rudiments of the stridulatory organs proper to the male; from whom it is probable that these have been transferred. Landois also found such rudiments on the under surface of the wing-covers of the female Achetidse, and on the femora of the female Acridiidae. In the Homoptera, also, the females have the proper musical apparatus in a functionless state ; and we shall hereafter meet in other divisions of the animal kingdom with many instances of structures proper to the male being present in a rudimentary condition in the female. Landois has observed another important fact, namely, that in the females of the Acridiidae, the stridulating teeth on the femora remain throughout life in the same condition in which they first appear during the larval state in both sexes. In the males, on the other hand, they become further developed, and acquire their perfect structure at the last moult, when the insect is mature and ready to breed. From the facts now given, we see that the means by which the males of the Orthoptera produce their sounds are extremely diversified, and are altogether different from those employed by the Homoptera.43 But throughout the animal kingdom wo often find the same object gained by the most diversified means ; this seems due to the whole organisation having undergone mui- . tifarious changes in the course of ages, and as part after part varied different variations were taken advantage of for the same general purpose. The diversity cf means for producing sound in the three families of the Orthoptera and in the ** Landois has recently found in moptera ; and this is a surprising c*rtam Orthoptera rudimentary fact. Stion of colour is certain. He says that the males search eagerly and fight for the possession of the females ; and he accounts through *" P. Huber, ' Recherches sur les Philadelphia,' 1866, pp. 23&-239. Moeurs des Fourmis,' 1810, pp. 150, " * Anwendung der Darwinsckea 165. Lehre auf Bienen/ Vsrn. a. a, * ' Proc. Entomolog. Soc. of JaLrg. xxix. Chap.X Hymenoptera. 293 such contests for the mandibles of the males being in certain species larger than those of the females. In some cases the males are far more numerous than the females, either early in the season, or at all times and places, or locally ; whereas the females in other cases are apparently in excess. In some species the more beautiful males appear to have been selected by the females ; and in others the more beautiful females by the males. Consequently in certain genera (Mtiller, p. 42), the males of the several species differ much in appearance, whilst the females are almost indistinguishable ; in other genera the reverse occurs. H. Miiller believes (p. 82) that the colours gained by one sex fiirough sexual selection have often been transferred in a variable degree to the other sex, just as the pollen-collecting apparatus of the female has often been transferred to the male, to whom it is absolutely useless.61 Mutilla .Europasa makes a stridulating noise ; and according to Goureau 62 both sexes have this power. He attributes the sound to the friction of the third and preceding abdominal segments, and I find that these surfaces are marked with very fine con- centric ridges ; but so is the projecting thoracic collar, into which the head articulates, and this collar, when scratched with the point of a needle, emits the proper sound. It is rather surprising that both sexes should have the power of stridulating, as the male is winged and the female wingless. It is notorious that Bees express certain emotions, as of anger, by the tone of their humming; and according to H. Miiller (p. 80), the males of some species make a peculiar singing noise whilst pursuing the females. 61 M. Perrier in his article * la Se- male grandfathers ? To take a case lection sexuelle d'apres Darwin* (' Re- with ordinary animals as nearly vue Scientifique/ Feb. 1873, p. 868), parallel as possible: if a female ol without apparently having reflected any white quadruped or bird were much on the subject, objects that as crossed by a male of a black breed, the males of social bees are known and the male and female offspring to be produced from unfertilised were paired together, will it be ova, they could not transmit new pretended that the grandchildren characters to their male offspring, would not inherit a tendency to This is an extraordinary objection, blackness from their male grand- A female bee fertilised by a male, father ? The acquirement of new which presented some character fa- characters by the sterile worker-bees cilitating the union of the sexes, or is a much more difficult case, but 1 rendering him more attractive to have endeavoured to show in my the female, would lay eggs which * Origin of Species,' how these steril a would produce only females ; but beings are subjected to the power ot these young females would next natural selection, year produce males , and will it be fl2 Quoted by Westwood, * Modern pretended that such males would Class, of Insects/ vol. ii. p. 214 not inherit the characters of their 294 The Descent of Man. PaktK Order, Coleoptera (Beetles). — Many beetles are coloured so as to resemble the surfaces which they habitually frequent, and they thus escape detection by their enemies. Other species, for instance diamond-beetles, are ornamented with splendid colours, which are often arranged in stripes, spots, crosses, and other elegant patterns. Such colours can hardly serve directly as a protection, except in the case of certain flower-feeding species ; but they may serve as a warning or means of recognition, on the same principle as the phosphorescence of the glow-worm. As with beetles the colours of the two sexes are generally alike, we have no evidence that they have been gained through sexual selection; but this is at ]east possible, for they may have been developed in one sex and then transferred to the other ; and this view is even in some degree probable in those groups which possess other well-marked secondary sexual characters. Blind beetles, which cannot of course behold each other's beauty, never, as I hear from Mr. Waterhouse, jun., exhibit bright colours, though they often have polished coats ; but the expla- nation of their obscurity may be that they generally inhabit caves and other obscure stations. Some Longicorns, especially certain Prionidse, offer an excep- tion to the rule that the sexes of beetles do not differ in colour. Most of these insects are large and splendidly coloured. The males in the genus Pyrodes,6a which I saw in Mr. Bates's col- lection, are generally redder but rather duller than the females, the latter being coloured of a more or less splendid golden-green. On the other hand, in one species the male is golden-green, the female being richly tinted with red and purple. In the genus Esmeralda the sexes differ so greatly in colour that they have been ranked as distinct species ; in one species both are of a beautiful shining green, but the male has a red thorax. On the whole, as far as I could judge, the females of those Prionidsa, in 63 Pyrodes pulcherrimus, in the family of Longicorns. Messrs which the sexes differ conspicuously, R. Trimen and Waterhouse, jun., has been described by Mr. Bates in inform me of two Lamellicorns, ' Transact. Ent. Soc* 1869, p. 50. viz., a Peritrichia and Trichius, the I will specify the few other cases in male of the latter being more which I have heard of a difference obscurely coloured than the female, in colour between the sexes of In Tillus elongatus the male is black, beetle*. Kirby and Spence ('In- and the female always, as it is troduct. to Entomology,' vol. iii. p. believed, of a dark blue colour, with 301) mention a Cantharis, Meloe, a red thorax. The male, also, of Rhagium, and the Leptura testacea ; Orsodacna atra, as I hear from Mr. the male of the latter being tes- Walsh, is black, the female (tht taceous, with a black thorax, and so-called 0. ruficollis) having a the female of a dull red all ovei. ^ifous thorax. These two latter beetles belong to Chap. X. Coleoptera. 295 which the sexes differ, are coloured more richly than the males, and this does not accord with the common rule in regard to colour, when acquired through sexual selection. A most remarkable distinction between the sexes of many- beetles is presented by the great horns which rise from the head, thorax, and clypeus of the males; and in some few cases from the under surface of the body. These horns, in the great family of the Lamellicorns, resemble. those of various quadrupeds, such as stags, rhinoceroses, &c, and are wonderful both from their size and diversified shapes. Instead of describing them, I have given figures of the males and females of some of the more re- markable forms. (Figs. 16 to 20.) The females generally ex- hibit rudiments of the horns in the form of small knobs or ridges ; but some are destitute of even the slightest rudiment. On the other hand, the horns are nearly as well developed in the female as in the male of Phanceus lancifer ; and only a little less well developed in the females of some other species of this genus and of Copris, I am informed by Mr. Bates that the horns do not differ in any manner corresponding with the more important characteristic differences between the several subdivisions of the family : thus within the same section of the genus Onthophagus, there are species which have a single horn, and others which have two. ^Fig, 16. CMoosoma atlas. Upper figure, male (reduced) ; lower figure, female (nat.size). 2Q6 The Descent of Man. Part II Copris isidis. (Left-hand figures, males.) Fig. 18. Phanasus faunus. Dipelicus cantori. Fig* 20. Onthophacrns rangifer. enlarged. Chap. X Coleoptera. 297 In almost all cases, the horns are remarkable from their ex- cessive variability ; so that a graduated series can be formed, from the most highly developed males to others so degenerate that they can barely be distinguished from the females. Mr. Walsh64 found that in Phanceus carnifea, the horns were thrice as long in some males as in others. Mr. Bates, after examining above a hundred males of Onthophagm rangifer (fig. 20), thought that he had at last discovered a species in which the horns did not vary ; but further research proved the contrary. The extraordinary size of the horns, and their widely different structure in closely-allied forms, indicate that they have been formed for some purpose ; but their excessive variability in the males of the same species leads to the inference that this purpose cannot be of a definite nature. The horns do not show marks of friction, as if used for any ordinary work. Some authors sup- pose65 that as the males wander about much more than the females, they require horns as a defence against their enemies; but as the horns are often blunt, they do not seem well adapted for defence. The most obvious conjecture is that they are used by the males for fighting together; but the males have never been observed to fight; nor could Mr. Bates, after a careful examination of numerous species, find any sufficient evidence, in their mutilated or broken condition, of their having been thus used. If the males had been habitual fighters, the size of their bodies would probably have been increased through sexual selection, so as to have exceeded that of the females; but Mr. Bates, after comparing the two sexes in above a hundred species of the CopridaB, did not find any marked difference in this respect amongst well-developed individuals. In Lethrus, moreover, a beetle belonging to the same great division of the Lamellicorns, the males are known to fight, but are not provided with horns, though their mandibles are much larger than those of the female. The conclusion that the horns have been acquired as ornaments is that which best agrees with the fact of their having been so immensely, yet not fixedly, developed, — as shewn by their extreme variability in the same species, and by their extreme diversity in closely-allied species. This view will at first appear extremely improbable; but we shall hereafter find with many animals standing much higher in the scale, namely fishes, amphibians, reptiles and birds, that various kinds of crests, knobs, horns and combs have been developed apparently for this sole purpose. The males of Onitis furcifer (fig. 21), and of some other ** ' Proc. Entomolog. Soc. of •* Kirby and Spence, ' Introduce Philadelphia, 1864, p. 228 Entomolog.' vol. iii. p. 300* S9» The Descent of Man, Part II. species of the genus, are furnished with singular projections on their anterior femora, and with a great fork or pair of horns on the lower surface of the thorax. Judging from other insects, these may aid the male in clinging to the female. Although the males have not even a trace of a horn on the upper surface of the body, yet the fe- males plainly exhibit a rudiment of a single horn on the head (fig. 22, a), and of a crest (b) on the thorax. That the slight thoracic «£ V >S cres* *n ^e ^ema^e *s a rudiment of a pro- T* * ' jection proper to the male, though entirely absent in the male of this particular species, is clear : for the female of Bubas bison (a genus which comes next to Onitis) has a similar slight crest on the thorax, and the male bears a great projection in the same situation. So, again, there can hardly be a doubt that the little point (a) on the head of the female Onitis Fig 21. Onitis furcifer, male viewed from be- neath. Fig. 22. Left-hand figure, male of Onitis furcifer, viewed laterally. Right-hand figure, female, a. Rudiment of cephalic horn. b. Trace of thoracic horn or crest. furcifer, as well as on the head of the females of two or three allied species, is a rudimentary representative of the cephalic horn, which is common to the males of so many Lamellicorn beetles, as in Phanseus (fig. 18). The old belief that rudiments have been created to complete the scheme of nature is here so far from holding good, that we have a complete inversion of the ordinary state of things in the family. We may reasonably suspect that the males originally bore horns and transferred them tc the females in a rudimentary condition, as in so many other Lamellicorns. Why the males subsequently lost their horns, we know not ; but this may have been caused through the principle of compensation, owing to the development of the large horns and projections on the lower surface ; and as these are confined to the males, the rudiments of the upper horns on the females would not have been thus obliterated. Chap. X. Coleoptera. 299 The cases hitherto given refer to the Lamellicorns, but the males of some few other beetles, belonging to two widely distinct groups, namely, the Curculionidae and StaphylinidaB, are fur- nished with horns — in the former on the lower surface of the body,66 in the latter on the upper surface of the head and thorax. In the Staphylinidae, the horns of the males are extraordinarily variable in the same species, just as we have seen with the Lamellicorns. In Siagonium we have a case of dimorphism, for the males can be divided into two sets, differing greatly in the size of their bodies and in the development of their horns, without intermediate gradations. In a species of Bledius (fig. 23), also belonging to the Staphylinidse, Professor Westwood Fig. 23. Bledius taurus, magnified. Left-hand figure, male ; right-handjgure female states that, " male specimens can be found in the same locality " in which the central horn of the thorax is very large, but the " horns of the head quite rudimental; and others, in which the "thoracic horn is much shorter, whilst the protuberances on " the head are long/'67 Here we apparently have a case of compensation, which throws light on that just given of the supposed loss of the upper horns by the males of Onitis. Law of Battle, — Some male beetles, which seem ill-fitted for fighting, nevertheless engage in conflicts for the possession of the females. Mr. Wallace68 saw two males of Leptorhynchus angustatus, a linear beetle with a much elongated rostrum, "' fighting for a female, who stood close by busy at her boring. * They pushed at each other with their rostra, and clawed and " thumped, apparently in the greatest rage." The smaller male, however, "soon ran away, acknowledging himself vanquished." In some few cases male beetles are well adapted for fighting, by possessing great toothed mandibles, much larger than those of the females. This is the case with the common stag-beetlo (Lucanus cervus), the males of which emerge from the pupal state about a week before the other sex, so that several may often be seen pursuing the same female. At this season they 66 Kirby and Spence, 'Introduct. gonium in an intermediate condi- Entomolog.' vol. ill. p. 329. tion, so that the dimorphism is not 67 * Modern Classification of In- strict. sects,' vol. i. p. 172: Siagonium, *>* 'The Malay Archipelago/ vol. p. 172. In the British Museum I ii. 1869, p. 276. Riley, Sixth < Report noticed one male specimen of §ia* on insects of Missouri/ 1874-,p. 114 300 The Descent of Man. Pabt H, engage in fierce conflicts. When Mr. A. H. Davis ^ enclosed two males with one female in a box, the larger male severely pinched the smaller one, until he resigned his pretensions. A friend informs me that when a boy he often put the males together to see them fight, and he noticed that they were much bolder and fiercer than the females, as with the higher animals. The males would seize hold of his finger, if held in front of them, but not so the females, although they have stronger jaws. The males of many of the Lucanidse, as well as of the above-mentioned Leptorhynchus, are larger and more powerful insects than the females. The two sexes of Lethrus cephalotes (one of the Lamellicorns) inhabit the same burrow; and the male has larger mandibles than the female. If, during the breeding-season, a strange male attempts to enter the burrow, he is attacked ; the female does not remain passive, but closes the mouth of the burrow, and encourages her mate by con- tinually pushing him on from behind ; and the battle lasts until the aggressor is killed or runs away.70 The two sexes of another Lamellicorn beetle, the Ateuchus cicatricosus, live in pairs, and seem much attached to each other ; the male excites the female to roll the balls of dung in which the ova are deposited ; and if she is removed, he becomes much agitated. If the male is removed the female ceases all work, and as M. Brulerie71 believes, would remain on the same spot until she died. The great mandibles of the male LucanidaB are extremely variable both in size and structure, and in this respect resemble the horns on the head and thorax of many male Lamellicorns and Staphylinidse. A perfect series can be formed from the best-provided to the worst-provided or degenerate males. Al- though the mandibles of the common stag-beetle, and probably of many other species, are used as eflicient weapons for fighting, it is doubtful whether their great size can thus be accounted for. We have seen that they are used by the Lucanus elcvphus of N. America for seizing the female. As they are so con- spicuous and so elegantly branched, and as owing to their great length they are not well adapted for pinching, the suspicion has crossed my mind that they may in addition serve as an ornament, like the horns on the head and thorax of the various species above described. The male Cktasognathus Grantii of S. Chile — a splendid beetle belonging to the same family — has 69 'Entomological Magazine,' vol. 70 Quoted from Fischer, in 'Diet, i. 1833, p. 82. See also on the Class. d'Hist. Nat.' torn. x. p. 324. conflicts of this species, Kirby and u ' Ann. Soc. Entomolog. France, Spence, ibid. vol. iii. p. 314; and 1866, as quoted in 'Journal of Westwood, ibid. vol. i. p. 187. Travel,' by A. Murray, 1968, p. 105, Chap. X. Coleoptera. 30X enormously developed mandibles (fig. 24) ; he is bold and pug- nacious ; when threatened he faces round, opens his great jaws, and at the same time stridulates loudly. But the mandibles were not strong enough to pinch my finger so as to cause actual pain. Sexual selection, which implies the possession of considerable perceptive powers and of strong passions, seems to have been more effective with the Lamellicorns than with any other family of beetles. "With some species the males are provided with weapons for fighting; some live in pairs and show mutual affection; many have the power of stridulating when excited ; many are furnished with the most ex- traordinary horns, apparently for the sake of ornament ; and some, which are diurnal in their habits, are gor- geously coloured. Lastly, several of the largest beetles in the world belong to this family, which was placed by LinnsBus and Fabricius at the head of the Order.72 Stridulating organs. — Beetles belong- ing to many and widely distinct families possess these organs. The sound thus produced can sometimes be heard at the distance of several feet or even yards,73 but it is not comparable with that made by the Orthoptera. The rasp generally consists of a narrow, slightly-raised surface, crossed by very fine, parallel ribs, sometimes so fine as to cause iridescent colours, and having a very elegant appearance under the microscope. In some cases, as with Typhosus, minute, bristly or scale-like prominences, with which the whole surrounding surface is covered in approximately parallel lines, could be traced passing into the ribs of the rasp. The Fier. 24. Chiasognathus grantii, reduced. Upper figure, male 5 lower figure, female. 72 Westwood, 'Modern Class/ rol. i. p. 184. n Wollaston, ' On certain Musical Curculionidae,' ' Annals and Mag. o\ Nat. Hist.' vol. vi. 1860, p. 14. 302 The Descent of Man. PartH. transition takes place by their becoming confluent and straight, and at the same time more prominent and smooth. A hard ridge on an adjoining part of the body serves as the scrape* for the rasp, but this scraper in some cases has been specially modified for the purpose. It is rapidly moved across the rasp, or conversely the rasp across the scraper. Fig. 25. Necrophorus (from Landois). r. The two rasps. Left-hand figure, part of the rasp highly magnified. These organs are situated in widely different positions. In the carrion-beetles (Necrophorus) two parallel rasps (r, fig. 25) stand on the dorsal surface of the fifth abdominal segment, each rasp74 consisting of 126 to 140 fine ribs. These ribs are scraped against the posterior margins of the elytra, a small portion of which projects beyond the general outline. In many Crioceridse, and in Clyikra punctata (one of the Chrysomelidae), and in some Tenebrionidse, &c.,75 the rasp is seated on the dorsal apex of the abdomen, on the pygidium or pro-pygidium, and is scraped in the same manner by the elytra. In Heterocerus, which belongs to another family, the rasps are placed on the sides of the first abdominal segment, and are scraped by ridges on the femora.76 In certain Curculionidss and Carabidse,77 the parts 74 Landois, 'Zeitschrift fur wiss. Zoolog.' B. xvii. 1867, s. 127. 75 I am greatly indebted to Mr. G. R. Crotch for having sent me many prepared specimens of various beetles belonging to these three families and to others, as well as for valuable information. He believes that the power of stridulation in the Clythra has not been previously observed. I am also much indebted to Mr. E. W. Janson, for informa- tion and specimens. I may add that my son, Mr. F. Darwin, finds that Dermestes murinus stridulates, but he searched in vain for the apparatus. Scolyius has lately been described by Dr. Chapman as a stridulator, in the 'Entomolo- gist's Monthly Magazine,' vol. vi. p. 130. 76 Schiodte, translated in ' Annals and Mag. of Nat. Hist.' vol. xx. 1867, p. 37. 77 Westring has described (Kroyer, * Naturhist. Tidskrift/ B. ii. 1848- 49, p. 334) the stridulating organs in these two, as well as in other families. In the Carabidse I have examined Elaphrus uliginosus and Blethisa multipwnctata, sent to me by Mr. Crotch. In Blethisa the transverse ridges on the furrowed border of the abdominal segment da Chap. X. Coleoptera. 303 are completely reversed in position, for the rasps are seated on the inferior surface of the elytra, near their apices, or along their outer margins, and the edges of the abdominal segments serve as the scrapers. In PeloUus Hermanni (one of Dytiscidas or water-beetles) a strong ridge runs parallel and near to the sutural margin of the elytra, and is crossed by ribs, coarse in the middle part, but becoming gradually finer at both ends, especially at the upper end; when this insect is held under water or in the air, a stridulating noise is produced by the extreme horny margin of the abdomen being scraped against the rasps. In a great number of long-horned beetles (Longi- cornia) the organs are situated quite otherwise, the rasp being on the meso-thorax, which is rubbed against the pro-thorax; Landois counted 238 very fine ribs on the rasp of Ceramhyx heros. Many Lamellicorns have the power of stridulating, and the organs differ greatly in position. Some species stridulate very loudly, so that when Mr. F. Smith caught a Trox sabuhsus, a gamekeeper, who stood by, thought he had caught a mouse ; but I failed to discover the proper organs in this beetle. In Geotrupes and Typhosus a narrow ridge runs obliquely across (r, fig. 26) the coxa of each hind-leg (having in G. ster- corals 84 ribs), which is scraped by a specially projecting part of one of the ab- dominal segments. In the nearly allied Copris 7unarzs, an excessively narrow fine rasp runs along the sutural margin of the elytra, with another short rasp near the basal outer mar- gin; but in some other Coprini the rasp is seated, according to Leconte,78 on the dorsal surface of the abdomen. In Oryctes it is seated on the pro-pygidium ; and, according to the same entomologist, in some other Dynastini, on the under surface of the elytra. Lastly, Westring states that in Omaloplia hrunnea the rasp is placed on the pro-sternum, and the scraper on the meta-sternum, the parts thus occupying the under surface of the body, instead of the upper surface as in the Longicorns. We thus see that in the different coleopterous families the Fig. 26. Hind-leg of Geotrupes stercora- rius (from Landois). r. Rasp. c. Coxa. /. Femur, t. Tibia tr. Tarsi. not, as far as I could judge, come into play in scraping the rasps on the elytra. ■ '" 1 ana indebted to Mr. Walsh, of Illinois, for having sent me ex- tracts from Leconte V Introduction to Entomology,' pp. 101, 143. 304 Ttie Descent of Man. Part XL etridulating organs are wonderfully diversified in position, but not much in structure. Within the same family some species are provided with these organs, and others are destitute of them. This diversity is intelligible, if we suppose that originally various beetles made a shuffling or hissing noise by the rubbing together of any hard and rough parts of their bodies, which happened to be in contact ; and that from the noise thus produced being in some way useful, the rough surfaces were gradually developed into regular stridulating organs. Some beetles as they move, now produce, either intentionally or unintentionally, a shuffling n/ise, without possessing any proper organs for the purpose. Mr. Wallace informs me that the Euchirus longimanus (a Lamellicorn, with the anterior legs wonderfully elongated in the male) " makes, whilst moving, a low hissing sound by the pro- " trusion and contraction of the abdomen ; and when seized it " produces a grating sound by rubbing its hind-legs against the " edges of the elytra." The hissing sound is clearly due to a narrow rasp running along the sutural margin of each elytron ; and I could likewise make the grating sound by rubbing the shagreened surface of the femur against the granulated margin of the corresponding elytron ; but I could not here detect any proper rasp ; nor is it likely that I could have overlooked it in so large an insect After examining Cychrus, and reading what Westring has written about this beetle, it seems very doubtful whether it possesses any true rasp, though it has the power of emitting a sound. From the analogy of the Orthoptera and Homoptera, I expected to find the stridulating organs in the Coleoptera differing according to sex; but Landois, who has carefully examined several species, observed no such difference ; nor did Westring; nor did Mr. G. E. Crotch in preparing the many specimens which he had the kindness to send me. Any difference in these organs, if slight, would, however, be difficult to detect, on account of their great variability. Thus, in the first pair of specimens of Necrophorus humator and of Pelobius which I ex- amined, the rasp was considerably larger in the male than in the female; but not so with succeeding specimens. In Geo- trupes stercorarim the rasp appeared to me thicker, opaquer, and more prominent in three males than in the same number of females; in order, therefore, to discover whether the sexes differed in their power of stridulating, my son, Mr. F. Darwin, collected fifty-seven living specimens, which he separated into two lots, according as they made a greater or lesser noise, when held in the same manner. He then examined all these specimens, and found that the males were very nearly in the same proportion Chap. X. Coleoptera. 305 to the females in both the lots. Mr. F. Smith has kept alive numerous specimens of Monoynchus pseudacoH (Gurculionidse), and is convinced that both sexes stridulate, and apparently in an equal degree. Nevertheless, the power of stridulating is certainly a sexual character in some few Coleoptera. Mr. Crotch discovered that the males alone of two species of Heliopathes (Tenebrionicke) possess stridulating organs. I examined live males of H. gibbus, and in all these there was a well-developed rasp, partially divided into two, on the dorsal surface of the terminal abdominal segment ; whilst in the same number of females there was not even a rudiment of the rasp, the membrane of this segment being transparent, and much thinner than in the male. In H. cribratostriatus the male has a similar rasp, excepting that it is not partially divided into two portions, and the female is completely destitute of this organ ; the male in addition has on the apical margins of the elytra, on each side of the suture, three or four short longitudinal ridges, which are crossed by extremely fine ribs, parallel to and resembling those on the abdominal rasp ; whether these ridges serve as an independent rasp, or as a scraper for the abdominal rasp, I could not decide : the female exhibits no trace of this latter structure. Again, in three species of the Lamellicorn genus Oryctes, we have a nearly parallel case. In the females of 0. gryphus and nasicornis the ribs on the rasp of the pro-pygidium are less continuous and less distinct than in the males; but the chief difference is that the whole upper surface of this segment, when held in the proper light, is seen to be clothed with hairs, which are absent or are represented by excessively fine down in the males. It should be noticed that in all Coleoptera the effective part of the rasp is destitute of hairs. In 0. senegalensis the difference between the sexes is more strongly marked, and this is best seen when the proper abdominal segment is cleaned and viewed as a transparent object. In the female the whole surface is covered with little separate crests, bearing spines ; whilst in the male these crests in proceeding towards the apex, become more and more confluent, regular, and naked ; so that three- fourths of the segment is covered with extremely fine parallel ribs, which are quite absent in the female. In the females, however, of all three species of Oryctes, a slight grating or stridulating sound is produced, when the abdomen of a softened specimen is pushed backwards and forwards. In the case of the Heliopathes and Oryctes there can hardly be a doubt that the males stridulate in order to call or to excite the females; but with most beetles the stridulation 306 The Descent of Man. Part II. apparently serves both sexes as a mutual call. Beetles stridu- late under various emotions, in the same manner as birds use their voices for many purposes besides singing to their mates. *fhe great Chiasognathus stridulates in anger or defiance ; many species do the same from distress or fear, if held so that they cannot escape; by striking the hollow stems of trees in the Canary Islands, Messrs. Wollaston and Crotch were able to discover the presence of beetles belonging to the genus Acalles by their stridulation. Lastly, the male Ateuchus stridulates to encourage the female in her work, and from distress when she is removed.79 Some naturalists believe that beetles make this noise to frighten away their enemies ; but I cannot think that a quadruped or bird, able to devour a large beetle, would be frightened by so slight a sound. The belief that the stridu- lation serves as a sexual call is supported by the fact that death- ticks (Anobium tessellation) are well known to answer each other's ticking, and, as I have myself observed, a tapping noise artificially made. Mr. Doubleday also informs me that he has sometimes observed a female ticking,80 and in an hour or two afterwards has found her united with a male, and on one occasion surrounded by several males. Finally, it is probable that the two sexes of many kinds of beetles were at first enabled to find each other by the slight shuffling noise produced by the rubbing together of the adjoining hard parts of their bodies; and that as those males or females which made the greatest noise succeeded best in finding partners, rugosities on various parts of their bodies were gradually developed by means of sexual selection into true stridulating organs. 79 M. P. de la Brulerie, as quoted Landois, * Zeitschrift f iir wissen. in * Journal of Travel,' A. Murray, Zoolog.' B. xvii. s. 131. Oliver vol. i. 1868, p. 135. says (as quoted by Kirby and 80 According to Mr. Doubleday, Spence, 4 Introduct.' vol. ii. p. 395) " the noise is produced by the in- that the female of Pimelia striata " sect raising itself on its legs as produce* a rather loud sound by " high as it can, and then striking striking her abdomen against any ** its thorax five or six times, in hard substance, " and that the male, ** rapid succession, against the sub- " obedient to this call, sow attend* ** stance upon which it is sitting." " her, *tid they pair." For references on this subiect see Chap. XI. Butterflies and Moths. 307 CHAPTER XL Insects, continued, — Order Lepidopteba. (butterflies and moths.) Courtship of butterflies— Battles — Ticking noise — Colours common to both sexes, or more brilliant in the males — Examples — Not due to the direct action of the conditions of life — Colours adapted for protection — Colours of moths — Display — Perceptive powers of the Lepidoptera— Variability — Causes of the difference in colour between the males and females — Mimicry, female butterflies more brilliantly coloured than the males — Bright colours of caterpillars — Summary and concluding remarks on the secondary sexual characters of insects — Birds and insects compared. In this great Order the most interesting points for us are the differences in colour between the sexes of the same species, and between the distinct species of the same genus. Nearly the whole of the following chapter will be devoted to this subject ; but I will first make a few remarks on one or two other points. Several males may often be seen pursuing and crowding round the same female. Their courtship appears to be a prolonged affair, for I have frequently watched one or more males pirouet- ting round a female until I was tired, without seeing the end of the courtship. Mr. A. G. Butler also informs me that he has several times watched a male courting a female for a full quarter of an hour ; but she pertinaciously refused him, and at last settled on the ground and closed her wings, so as to escape from his addresses. Although butterflies are weak and fragile creatures, they are pugnacious, and an Emperor butterfly * has been captured with the tips of its wings broken from a conflict with another male. Mr. Collingwood, in speaking of the frequent battles between the butterflies of Borneo, says, " They whirl round each other with " the greatest rapidity, and appear to be incited by the greatest " ferocity." The Ageronia feronia makes a noise like that produced by a toothed wheel passing under a spring catch, and which can be heard at the distance of several yards : I noticed this sound at Kio de Janeiro, only when two of these butterflies were chasing each other in an irregular course, so that it is probably made during the courtship of the sexes.2 1 Apatura Iris : ' The Entomolo- Naturalist,' 1868, p. 183. gtst's Weekly Intelligence/ 1859, p. 2 See my ' Journal of Researches, 139. For the Bornaan Butterflies, 1845, p. 33, Mr. Doubleday has fee C. Collingwood, 'Rambles of a detected (' Proc. Ent. Soc/ March x 2 308 The Descent of Man. Paet IL Some moths also produce sounds ; for instance, the males of Thecophora fovea. On two occasions Mr. F. Buchanan White8 heard a sharp quick noise made by the male of Hylophila prasinana, and which he believes to be produced, as in Cicada, by an elastic membrane, furnished with a muscle. He quotes, also, Guenee, that Setina produces a sound like the ticking of a watch, apparently by the aid of " two large tympaniform " vesicles, situated in the pectoral region;" and these "are much " more developed in the male than in the female/' Hence the sound-producing organs in the Lepidoptera appear to stand in some relation with the sexual functions. I have not alluded to the well-known noise made by the Death's Head Sphinx, for it is generally heard soon after the moth has emerged from its cocoon. Girard has always observed that the musky odour, which is emitted by two species of Sphinx moths, is peculiar to the males ;4 and in the higher classes we shall meet with many instances of the males alone being odoriferous. Every one must have admired the extreme beauty of many butterflies and of some moths ; and it may be asked, are their colours and diversified patterns the result of the direct action of the physical conditions to which these insects have been exposed, without any benefit being thus derived ? Or have successive variations been accumulated and determined as a protection, or for some unknown purpose, or that one sex may be at- tractive to the other ? And, again, what is the meaning of the colours being widely different in the males and females of certain species, and alike in the two sexes of other species of the same genus ? Before attempting to answer these questions a body of facts must be given. With our beautiful English butterflies, the admiral, peacock, and painted lady (VanesssB), as well as many others, the sexes are alike. This is also the case with the magnificent Heliconidse, and most of the Danaidse in the tropics. But in certain other tropical groups, and in some of our English butterflies, as the purple emperor, orange-tip, &c. (Apatwra Iris and Anthocharis cardamines), the sexes differ either greatly or slightly in colour. No language suffices to describe the splendour of the males of 3rd, 1845, p. 123) a peculiar mem- observations, * The Scottish Natural branous sac at the base of the ist/ July 1872, p. 214. front wings, which is probably con- 3 * The Scottish Naturalist/ Jul} nected with the production of the 1872, p. 213. sound. For the case of Thecophora, 4 * Zoological Record,' 1869, p, roe ' Zoological Record,' 1869, p. 347, 401. Foi Mr. Buchanan Wh^'s CfcAK XL Butterflies ana Moths. 309 some tropical species. Even within the same genus we often find species presenting extraordinary differences between the sexes, whilst others have their sexes closely alike. Thus in the South American genus Epicalia, Mr. Bates, to whom I am indebted for most of the following facts, and for looking over this whole discussion, informs me that he knows twelve species, the two sexes of which haunt the same stations (and this is not always the case with butterflies), and which, therefore, cannot have been differently affected by external conditions.5 In nine of these twelve species the males rank amongst the most brilliant of all butterflies, and differ so greatly from the comparatively plain females that they were formerly placed in distinct genera. The females of these nine species resemble each other in their general type of coloration; and they likewise resemble both sexes of the species in several allied genera, found in various parts of the world. Hence we may infer that these nine species, and probably all the others of the genus, are descended from an ancestral form which was coloured in nearly the same manner. In the tenth species the female still retains the same general colouring, but the male resembles her, so that he is coloured in a much less gaudy and contrasted manner than the males of the previous species. In the eleventh and twelfth species, the females depart from the usual type, for they are gaily decorated almost like the males, but in a somewhat less degree. Hence in these two latter species the bright colours of the males seem to have been transferred to the females ; whilst in the tenth species the male has either retained or recovered the plain colours of the female, as well as of the parent-form of the genus. The sexes in these three cases have thus been rendered nearly alike, though in an opposite manner. In the allied genus Eubagis, both sexes of sonne of the species are plain-coloured and nearly alike ; whilst with the greater number the males are decorated with beautiful metallic tints in a diversified manner, and differ much from their females. The females throughout the genus retain the same general style of colouring, so that they resemble one another much more closely than they resemble their own males. In the genus Papilio, all the species of the iEneas group are remarkable for their conspicuous and strongly contrasted colours, and they illustrate the frequent tendency to gradation in the amount of difference between the sexes. In a few species, for instance in P. ascanius, the males and females are alike; in * See also Mr. Bates's paper in the same subject, in regard *o * Proc. Ent. Soc. of Philadelphia,* Diadema, in * Transact. Entomolog, 1805, p. 206. Also Mr. Wallace on Soc. of London/ 1869, p. 278. 3 IO The Descent of Man. Part W others the males are either a little brighter, or very much more superb than the females. The genus Junonia, allied to our Vanessae, offers a nearly parallel case, for although the sexes of most of the species resemble each other, and are destitute of rich colours, yet in certain species, as in J, cenone, the male is rather more bright-coloured than the female, and in a few (for instance J. andremiaja) the male is so different from the female that he might be mistaken for an entirely distinct species. Another striking case was pointed out to me in the British Museum by Mr. A. Butler, namely, one of the tropical American Theclse, in which both sexes are nearly alike and wonderfully splendid ; in another species the male is coloured in a similarly gorgeous manner, whilst the whole upper surface of the female is of a dull uniform brown. Our common little English blue butterflies of the genus Lycsena, illustrate the various dif- ferences in colour between the sexes, almost as well, though not in so striking a maimer, as the above exotic genera. In Lycxna agestis both sexes have wings of a brown colour, bordered with small ocellated orange spots, and are thus alike. In L. cegon the wings of the male are of a fine blue, bordered with black whilst those of the female are brown, with a similar border, closely resembling the wings of L. agestis. Lastly, in L. avion both sexes are of a blue colour and are very like, though in the female the edges of the wings are rather duskier, with the black spots plainer ; and in a bright blue Indian species both sexes are still more alike. I have given the foregoing details in order to show, in the first place, that when the sexes of butterflies differ, the male as a general rule is the more beautiful, and departs more from the usual type of colouring of the group to which the species belongs. Hence in most groups the females of the several species resemble each other much more closely than do the males. In some cases, however, to which I shall hereafter allude, the females are coloured more splendidly than the males. In the second place, these details have been given to bring clearly before the mind that within the same genus, the two sexes frequently present every gradation from no difference in colour, to so great a difference that it was long before the two were placed by entomologists in the same genus. In the third place, we have seen that when the sexes nearly resemble each other, this appears due either to the male having transferred his colours to the female, or to the male having retained, or perhaps recovered, the primordial colours of the group. It alsc deserves notice that in those groups in which the sexes differ, the females usually somewhat resemble the males, so that when GtiAp. XL Butterflies and Moths. 311 the males are beautiful to an extraordinary degree, the females almost invariably exhibit some degree of beauty. From the many cases of gradation in the amount of difference between the sexes, and from the prevalence of the same general type of coloration throughout the whole of the same group, we may con- clude that the causes have generally been the same which have determined the brilliant colouring of the males alone of some species, and of both sexes of other species. As so many gorgeous butterflies inhabit the tropics, it has often been supposed that they owe their colours to the great heat and moisture of these zones ; but Mr. Bates 6 has shewn by the comparison of various closely-allied groups of insects from the temperate and tropical regions, that this view cannot be maintained ; and the evidence becomes conclusive when bril- liantly-coloured males and plain-coloured females of the same species inhabit the same district, feed on the. same food, and follow exactly the same habits of life. Even when the sexes resemble each other, we can hardly believe that their brilliant and beautifully-arranged colours are the purposeless result of the nature of the tissues and of the action of the surrounding conditions. With animals of all kinds, whenever colour has been modified for some special purpose, this has been, as far as we can judge, either for direct or indirect protection, or as an attraction between the sexes. With many species of butterflies the upper surfaces of the wings are obscure; and this in all probability leads to their escaping observation and danger. But butterflies would be particularly liable to be attacked by their enemies when at rest ; and most kinds whilst resting raise their wings vertically over their backs, so that the lower surface alone is exposed to view. Hence it is this side which is often coloured so as to imitate the objects on which these insects commonly rest. Dr. Ebssler, I believe, first noticed the similarity of the closed wings of certain VanessaB and other butterflies to the bark of trees. Many analogous and striking facts could be given. The most interesting one is that recorded by Mr. Wallace 7 of a common Indian and Sumatran butterfly (Kallima), which disappears like magic when it settles on a bush ; for it hides its head and antennae between its closed wings, which, in form, colour and veining, cannot be distinguished from a withered leaf with its footstalk. In some other cases the lower 8 'The Naturalist on the Ama- 1867, p. 10. A woodcut of th* zoos/ vol. i. 1863, p. 19. Kallima is given by Mr. Wallace in 7 S?e the interesting article in ' Hard wickers Science Gossip,' Sept, the * Westminster Review,' July 1867, p. 196. 312 The Descent of Man. Pabt IL surfaces of the wings are brilliantly coloured, and jet are protective ; thus in Thecla rubi the wings when closed are of an emerald green, and resemble the young leaves of the bramble, on which in spring this butterfly may often be seen seated. It is also remarkable that in very many species in which the sexes differ greatly in colour on their upper surface, the lower surface is closely similar or identical in both sexes, and serves as a protection.8 Although the obscure tints both of the up])er and under sides of many butterflies no doubt serve to conceal them, yet we cannot extend this view to the brilliant and conspicuous colours on the upper surface of such species as our admiral and peacock Vanessse, our white cabbage-butterflies (Pieris), or the great swallow-tail Papilio which haunts the open fens — for these butterflies are thus rendered visible to every living creature. In these species both sexes are alike ; but in the common brim- stone butterfly (Gonepteryx rhamni), the male is of an intense yellow, whilst the female is much paler; and in the orange- tip (Anthocharis cardamines) the males alone have their wings tipped with bright orange. Both the males and females in these cases are conspicuous, and it is not credible that their difference in colour should stand in any relation to ordinary protection. Prof. Weismann remarks,9 that the female of one of the LycsensB expands her brown wings when she settles on the ground, and is then almost invisible ; the male, on the other hand, as if aware of the danger incurred from the bright blue of the upper surface of his wings, rests with them closed ; and this shews that the blue colour cannot be in any way protective. Nevertheless, it is probable that conspicuous colours are in- directly beneficial to many species, as a warning that they are unpalatable. For in certain other cases, beauty has been gained through the imitation of other beautiful species, which inhabit the same district and enjoy an immunity from attack by being in some way offensive to their enemies; but then we have to account for the beauty of the imitated species. As Mr. Walsh has remarkad to me, the females of our orange- tip butterfly, above referred to, and of an American species (Anth. genutia) probably shew us the primordial colours of the parent-species of the genus; for both sexes of four or five widely-distributed species are coloured in nearly the same manner. As in several previous cases, we may here infer that it is the males of Anth. cardamines and genutia which have departed from the usual type of the genus. In the Anth. sara 8 Mr. G. Fraser, in < Nature,' 9 < Einfluss der Isolirong anf di» April 1871, p. 489. Artbildimg,' 1872, p. 58. Chap. XI. Butterflies and Moths. 3 1 3 from California, the orange-tips to the wings have been partially developed in the female ; but they are paler than in the male, and slightly different in some other respects. In an allied Indian form, the Iphias glaucippe, the orange-tips are fully developed in both sexes. In this Iphias, as pointed out to me by Mr. A. Butler, the under surface of the wings marvellously resembles a pale- coloured leaf; and in our English orange-tip, the under surface resembles the flower-head of the wild parsley, on which the butterfly often rests at night.10 The same reason which compels us to believe that the lower surfaces have here been coloured for the sake of protection, leads us to deny that the wings have been tipped with bright orange for the same purpose, especially when this character is confined to the males. Most Moths rest motionless during the whole or greater part of the day with their wings depressed ; and the whole upper surface is often shaded and coloured in an admirable manner, as Mr. Wallace has remarked, for escaping detection. The front- wings of the Bombycidse and Noctuidse,11 when at rest, generally overlap and conceal the hind- wings; so that the latter might be brightly coloured without much risk; and they are in fact often thus coloured. During flight, moths would often be able to escape from their enemies ; nevertheless, as the hind-wings are then fully exposed to view, their bright colours must generally have been acquired at some little risk. But the following fact shews how cautious we ought to be in drawing conclusions on this head. The common Yellow Under- wings (TriphsBna) often fly about during the day or early evening, and are then conspicuous from the colour of their hind- wings. It would naturally be thought that this would be a source of danger ; but Mr. J. Jenner Weir believes that it actually serves them as a means of escape, for birds strike at these brightly coloured and fragile surfaces, instead of at the body. For in- stance, Mr. Weir turned into his aviary a vigorous specimen of Triphcena pronuba, which was instantly pursued by a robin; but the bird's attention being caught by the coloured wings, the moth wajs not captured until after about fifty attempts, and small portions of the wings were repeatedly broken off. He tried the same experiment, in the open air, with a swallow and T. fimbria; but the large size of this moth probably interfered with its capture.12 We are thus reminded of a statement made 10 See the interesting observations Science Gossip/ Sept. 1867, p. 193. by Mr. T. W. Wood, * The Student/ 12 See also, on this subject, Mr. Sept. 1868, p. 81. Weir's paper in * Transact. Ent. Soc." 11 Mr. Wallace in 'Hardwicke's 1869, p. 23. 314 The Descent of Man. Past It by Mr. Wallace,13 namely, that in the Brazilian forests and Malayan islands, many common and highly-decorated butterflies are weak flyers, though furnished with a broad expanse of wing ; and they " are often captured with pierced and broken wings, " as if they had been seized by birds, from which they had " escaped : if the wings had been much smaller in proportion u to the body, it seems probable that the insect would more " frequently have been struck or pierced in a vital part, and *' thus the increased expanse of the wings may have been in- * directly beneficial." Display, — The bright colours of many butterflies and of some moths are specially arranged for display, so that they may be readily seen. During the night colours are not visible, and there can be no doubt that the nocturnal moths, taken as a body, are much less gaily decorated than butterflies, all of which are diurnal in their habits. But the moths of certain families, such as the Zygsenidse, several Sphingidse, Uraniidse, some Arctiidse and Saturniidse, fly about during the day or early evening, and many of these are extremely beautiful, being far brighter coloured than the strictly nocturnal kinds. A few exceptional cases, however, of brightrcoloured nocturnal species have been recorded.14 There is evidence of another kind in regard to display. Butterflies, as before remarked, elevate their wings when at rest, but whilst basking in the sunshine often alternately raise and depress them, thus exposing both surfaces to full view ; and although the lower surface is often coloured in an obscure manner as a protection, yet in many species it is as highly decorated as the upper surface, and sometimes in a very different manner. In some tropical species the lower surface is even more brilliantly coloured than the upper.16 In ti?e Eng- lish fritillaries (Argynnis) the lower surface alone is orna- mented with shining silver. Nevertheless, as a general rule, the upper surface, which is probably more fully exposed, is coloured more brightly and diversely than the lower. Hence the lower surface generally affords to entomologists the more 11 * Westminster Review/ July Insects of New England,' 1842, p. 315. 1867, p. 16. 15 Such differences between the 14 For instance, Lithosia ; but upper and lower surfaces of the Prof. Westwood (* Modern Class, of wings of several species of PapiHo, Insects,' vol. ii. p. 390) seems sur- may be seen in the beautiful plates prised at this case. On the relative to Mr. Wallace's * Memoir on the colours of diurnal and nocturnal Papilionidse of the Malayan Region/ Lepidoptera, see ibid. pp. 333 and in * Transact. Linn. Soc.' vol. xxv. S92 j also Harris, 4 Treatise on the part i. 1865. Chap. XI Butterflies and Moths. 315 useful character for detecting the affinities of the various species. Fritz Mull er informs me that three species of Castnia are found near his house in S. Brazil : of two of them the hind- wings are obscure, and are always covered by the front- winga when these butterflies are at rest; but the third species has black hind-wings, beautifully spotted with red and white, and these are fully expanded and displayed whenever the butterfly rests. Other such cases could be added. If we now turn to the enormous group of moths, which, as I hear from Mr. Stainton, do not habitually expose the under surface of their wings to full view, we find this side very rarely coloured with a brightness greater than, or even equal to, that of the upper side. Some exceptions to the rule, either real or apparent, must be noticed, as the case of Hypopyra.16 Mr. Trimen informs me that in Guenee's great work, three moths are figured, in which the under surface is much the more brilliant. For instance, in the Australian Gastrophora the upper surface of the fore-wing is pale greyish-ochreous, while the lower surface is magnificently ornamented by an ocellus of cobalt-blue, placed in the midst of a black mark, surrounded by orange-yellow, and this by bluish^white. But the habits of these three moths are unknown ; so that no explanation can be given of their unusual style of colouring. Mr. Trimen also informs me that the lower surface of the wings in certain other GeometrsB17 and quadrifid NoctusB are either more variegated or more brightly-coloured than the upper surface; but some of these species have the habit of " holding their wings quite erect " over their backs, retaining them in this position for a con- " siderable time," and thus exposing the under surface to view. Other species, when settled on the ground or herbage, now and then suddenly and slightly lift up their wings. Hence the lower surface of the wings being brighter than the upper surface in certain moths is not so anomalous as it at first appears. The Saturniidae include some of the most beautiful of all moths, their wings being decorated, as in our British Emperor moth, with fine ocelli ; and Mr. T. W. Wood18 observes that they resemble butterflies in some of their movements; "for " instance, in the gentle waving up and down of the wings as if " for display, which is more characteristic of diurnal than of " nocturnal Lepidoptera." 18 See Mr. Wormald on this the GeoinetrcB) in 'Transact. Eat. vnoth : *Proc. Ent. Soc.' March 2nd, Soc.' new series, vo]. v. pi. xr. and 1868. xvi- " See also an account of the S. *• * Proc. Ent. Soc. of London/ American genus Erateina (cne of July 6, 1 S68, p. xxyii. 3 * 6 The Descent of Man. Past TI It is a singular fact that no British moths which are bril- liantly coloured, and, as far as I can discover, hardly any foreign species, differ much in colour according to sex ; though this is the case with many brilliant butterflies. The male, however, oi one American moth, the Saturnia lo, is described as having its fore-wings deep yellow, curiously marked with purplish-red spots ; whilst the wings of the female are purple-brown, marked with grey lines.19 The British moths which differ sexually in colour are all brown, or of various dull yellow tints, or nearly white. In several speGies the males are much darker than the females,20 and these belong to groups which generally fly about during the afternoon. On the other hand, in many genera, as Mr. Stainton informs me, the males have the hind- wings whiter than those of the female — of which fact Agrotis exclamationis offers a good instance. In the Ghost Moth (Hepialus humuli) the difference is more strongly marked ; the males being white, and the females yellow with darker markings.21 It is probable that in these cases the males are thus rendered more conspicuous, and more easily seen by the females whilst flying about in the dusk. From the several foregoing facts it is impossible to admit that the brilliant colours of butterflies, and of some few moths, have commonly been acquired for the sake of protection. We have seen that their colours and elegant patterns are arranged and exhibited as if for display. Hence I am led to believe that the females prefer or are most excited by the more brilliant 19 Harris, 'Treatise,* &c, edited which were fond of eating othei by Flint, 1862, p. 395. moths ; so that if the Cycnia was *° For instance, I observe in my commonly mistaken by British birds son's cabinet that the males are for the Spilosoma, it would escape darker than the females in the being devoured, and its white de- Zasiocampa quercus, Odonestis pota- ceptive colour would thus be highly toria, Hypogymna dispar, Dasychira beneficial. \ pudibunda, and Cycnia mendica. In 21 It is remarkable, that in the this latter species the difference in Shetland Islands the male of this colour between the two sexes is moth, instead of differing widely strongly marked ; and Mr. Wallace from the female, frequently re- informs me that we here have, as sembles her closely in colour (see he believes, an instance of protective Mr. MacLachlan, ' Transact. lint. mimicry confined to one sex, as Soc* vol. ii. 1866, p. 459). Mr. will hereafter be more fully ex- G. Fraser suggests (« Nature,* April plained. The white female of the 1871, p. 489) that at the season of Cycnia resembles the very common the year when the ghost-moth ap- Spilosoma menthrasti, both sexes of pears in these northern islands, ths which are white ; and Mr. Stainton whiteness of the males would not observed that this latter moth was be needed to render them visible to rejected with utter disgust by a the females in the twilight night, whole brood of young turkeys, Chap. XI. Butterflies and Moths. 31*" males ; for on any other supposition the males would, as far as we can see, be ornamented to no purpose. We know that ants and certain Lamellicorn beetles are capable of feeling an attach- ment for each other, and that ants recognise their fellows after an interval of several months. Hence there is no abstract improbability in the Lepidoptera, which probably stand nearly or quite as high in the scale as these insects, having sufficient mental capacity to admire bright colours. They certainly discover flowers by colour. The Humming-bird Sphinx may often be seen to swoop down from a distance on a bunch of flowers in the midst of green foliage ; and I have been assured by two persons abroad, that these moths repeatedly visit flowers painted on the walls of a room, and vainly endeavour to insert their proboscis into them. Fritz MUller informs me that several kinds of butterflies in S. Brazil shew an unmistakable prefer- ence for certain colours over others: he observed that they very often visited the brilliant red flowers of five or six genera of plants, but never the white or yellow flowering species of the same and other genera, growing in the same garden; and 1 have received other accounts to the same effect. As I hear from Mr. Doubleday, the common white butterfly often flies down to a bit of paper on the ground, no doubt mistaking it for one of its own species. Mr. Collingwood22 in speaking of the difficulty in collecting certain butterflies in the Malay Archipelago, states that "a dead specimen pinned upon a " conspicuous twig will often arrest an insect of the same species " in its headlong flight, and bring it down within easy reach of " the net, especially if it be of the opposite sex." The courtship of butterflies is, as before remarked, a prolonged affair. The males sometimes fight together in rivalry; and many may be seen pursuing or crowding round the same female. Unless, then, the females prefer one male to another, the pairing must be left to mere chance, and this does not appear probable. If, on the other hand, the females habitually, or even occasionally, prefer the more beautiful males, the colours of the latter will have been rendered brighter by degrees, and will have been transmitted to both sexes or to one sex, according to the law of inheritance which has prevailed. The process of sexual selection will have been much facilitated, if the conclusion can be trusted, arrived at from various kinds of evidence in the supplement to the ninth chapter; namely, that the males of many Lepidoptera, at least in the imago state, greatly exceed the females in number. Some facts, however, are opposed to the belief that female ** ' Rambles of a Naturalist in the Chinese Seas/ 1868, p. 182. 3 1 8 The Descent of Man. Part II, butterflies prefer the more beautiful males ; thus, as I hare been assured by several collectors, fresh females may frequently be seen paired with battered, faded, or dingy males ; but this is a circumstance which could hardly fail often to follow from the males emerging from their cocoons earlier than the females. With moths of the family of the Bombycidse, the sexes pair immediately after assuming the imago state; for they cannot feed, owing to the rudimentary condition of their mouths. The females, as several entomologists have remarked to me, lie in an almost torpid state, and appear not to evince the least choice in regard to their partners. This is the case with the common silk-moth (B. mori)y as I have been told by some continental and English breeders. Dr. Wallace, who has had great experience in breeding Bombyx cynthia, is convinced that the females evince no choice or preference. He has kept above 300 of these moths together, and has often found the most vigorous females mated with stunted males. The reverse appears to occur seldom ; for, as he believes, the more vigorous males pass over the weakly females, and are attracted by those endowed with most vitality. Nevertheless, the Bombycidse, though obscurely-coloured, are often beautiful to our eyes from their elegant and mottled shades. I have as yet only referred to the species in which the males are brighter coloured than the females, and I have attributed their beauty to the females for many generations having chosen and paired with the more attractive males. But converse cases occur, though rarely, in which the females are more brilliant than the males ; and here, as I believe, the males have selected the more beautiful females, and have thus slowly added to their beauty. W« do not know why in various classes of animals the males of some few species have selected the more beautiful females instead of having gladly accepted any female, as seems to be the general rule in the animal kingdom; but it, contrary to what generally occurs with the Lepidoptera, the females were much more numerous than the males, the latter would be likely to pick out the more beautiful females. Mr. Butler shewed me several species of Callidryas in the British Museum, in some of which the females equalled, and in others greatly surpassed the males in beauty; for the females alone have the borders of their wings suffused with crimson and orange, and spotted with black. The plainer males of these species closely resemble each other, showing that here the females have been modified ; whereas in those cases, where the males are the more ornate, it is these which have been modified, the females remaining closely alike. Chap. XI. Butterflies and Moths. 319 In England we have some analogous cases, though not bo marked. The females alone of two species of Thecla have a bright-purple or orange patch on their fore-wings. In Hip- parchia the sexes do not differ much ; but it is the female of H. janira which has a conspicuous light-brown patch on her wings ; and the females of some of the other species are brighter coloured than their males. Again, the females of Colias edusa and hyale have " orange or yellow spots on the black marginal (t border, represented in the males only by thin streaks;" and in Pieris it is the females which " are ornamented with black " spots on the fore-wings, and these are only partially present " in the males." Now the males of many butterflies are known to support the females during their marriage flight ; but in the species just named it is the females which support the males ; so that the part which the two sexes play is reversed, as is their relative beauty. Throughout the animal kingdom the males commonly take the more active share in wooing, and their beauty seems to have been increased by the females having accepted the more attractive individuals ; but with these but- terflies, the females take the more active part in the final mar- riage ceremony, so that we may suppose that they likewise do so in the wooing; and in this case we can understand how it is that they have been rendered the more beautiful.' Mr. Meldola, from whom the foregoing statements have been taken, says in conclusion ; " Though I am not convinced of the action of " sexual selection in producing the colours of insects, it cannot " be denied that these facts are strikingly corroborative of " Mr. Darwin's views."2* As sexual selection primarily depends on variability, a few words must be added on this subject. In respect to colour there is no difficulty, for any number of highly variable Lepi- doptera could be named. One good instance will suffice. Mr. Bates shewed me a whole series of specimens of Papilio sesostris an 1 P. childrence ; in the latter the males varied much in the extent of the beautifully enamelled green patch on the fore- wings, and in the size of the white mark, and of the splendid crimson stripe on the hind- wings ; so that there was a great contrast amongst the males between the most and the least gaudy. The male of Papilio sesostris is much less beautiful than of P. childrence ; and it likewise varies a little in the size of 23 'Nature/ April 27th, 1871, p. whilst pairing. See also Mr. G, 508. Mr. Meldola quotes Donzel, Fraser, in 'Nature/ April 20th, in ' Soc. Ent. de France/ 1837, p. 1871, p. 489, on the sexual differ- 77, on the flight of butterflies ences of several British to tterflies. j20 The Descent of Man. Part n the green patch on the fore-wings, and in the occasional ap- pearance of the small crimson stripe on the hind-wings, borrowed, as it would seem, from its own female ; for the femalea of this and of many other species in the iEneas group possess this crimson stripe. Hence between the brightest specimens of P. sesostris and the dullest of P. childrence, there was but a small interval ; and it was evident that as far as mere varia- bility is concerned, there would be no difficulty in permanently increasing the beauty of either species by means of selection. The variability is here almost confined to the male sex; but Mr. Wallace and Mr. Bates have shewn24 that the females of some species are extremely variable, the males being nearly constant. In a future chapter I shall have occasion to shew that the beautiful eye-like spots, or ocelli, found on the wings of many Lepidoptera, are eminently variable. I may here add that these ocelli offer a difficulty on the theory of sexual selection ; for though appearing to us so ornamental, they are never present in one sex and absent in the other, nor do they ever differ much in the two sexes.26 This fact is at present inexplicable ; but if it should hereafter be found that the for- mation of an ocellus is due to some change in the tissues of the wings, for instance, occurring at a very early period ox development, we might expect, from what we know of the laws of inheritance, that it would be transmitted to both sexes, though arising and perfected in one sex alone. On the whole, although many serious objections may be urged, it seems probable that most of the brilliantly coloured species of Lepidoptera owe their colours to sexual selection, excepting in certain cases, presently to be mentioned, in which conspicuous colours have been gained through mimicry as a protection. From the ardour of the male throughout the animal kingdom, he is generally willing to accept any female ; and it is the female which usually exerts a choice. Hence, if sexual selection has been efficient with the Lepidoptera, the male, when the sexes differ, ought to be the more brilliantly coloured, and this undoubtedly is the case. When both sexes are brilliantly coloured and resemble each other, the characters acquired by the males appear to have been transmitted to both. 24 Wallace on the Papilionidac of tomolog. Soc/ Nov. 19th, 1866. p. the Malayan Region, in * Transact, si. Linn. Soc.' vol. xxv. 1865, pp. 8, 25 Mr. Bates was so kind as to *}6. A striking case of a rare lay this subject before the Entonoo- variety, strictly intermediate be- logical Society, and I hare received tween two other well-marked female answers to this effect from scrsral rarieties, is given by Mr. Wallace, entomologists. See also Mr. Bates, in ' Proc. En- Chap. XL Butterflies and Moths. 3 2 1 We are led to this conclusion by cases, even within the same genus, of gradation from an extraordinary amount of difference to identity in colour between the two sexes. But it may be asked whether the differences in colour between the sexes may not be accounted for by other means besides sexual selection. Thus the males and females of the same species of butterfly are in several cases known26 to inhabit different stations, the former commonly basking in the sunshine, the latter haunting gloomy forests. It is therefore possible that different conditions of life may have acted directly on the two sexes ; but this is not probable,27 as in the adu.*t state they are exposed to different conditions during a very short period ; and the larvaa of both are exposed to tLe same conditions. Mr. Wallace believes that the difference between the sexes is due not so much to the males having been modified, as to the females having in all or almost all cases acquired dull colours for the sake of protection. It seems to me, on the contrary, far more probable that it is the males which have been chiefly modified through sexual selection, the females having been comparatively little changed. We can thus understand how it is that the females of allied species generally resemble one another so much more closely than do the males. They thus shew us ap- proximately the primordial colouring of the parent-species of the group to which they belong. They have, however, almost always been somewhat modified by the transfer to them of some of the successive variations, through the accumulation of which the males were rendered beautiful. But I do not wish to deny that the females alone of some species may have been specially modified for protection. In most cases the males and females of distinct species will have been exposed during their prolonged larval state to different conditions, and may have been thus affected ; though with the males any slight change of colour thus caused will generally have been masked by the brilliant tints gained through sexual selection. When we treat of Birds, I shall have to discuss the whole question, as to how far the differences in colour between the sexes are due to the males having been modified through sexual selection for ornamental purposes, or to the females having been modified through natural selection for the sake of protection, so that I will here say but little on the subject. In all the cases in which the more common form of equal 28 H. W. Bates, 'The Naturalist 2T On this whole subject see 'The cm tV Amazons/ vol. ii. 1863, p. Variation of Animals and Plants 228. A. R. Wallace, in * Transact. wader Domesticat on,' 1868, vol. ii Juinn. Soc.' vol. xxv. 1865, p. 10. chap, jxiii. y 322 The Descent of Man. Tart II. inheritance by both, sexes has prevailed, the selection of bright- coloured males would, tend to make the females bright-coloured; and the selection of dull-coloured females would tend, to make the males dull. If both processes were carried on simultaneously, they would tend to counteract each other ; and the final result would depend on whether a greater number of females from being well protected by obscure colours, or a greater number of males by being brightly-coloured and thus finding partners, succeeded in leaving more numerous offspring. In order to account for the frequent transmission of characters to one sex alone, Mr. Wallace expresses his belief that the more common form of equal inheritance by both sexes can be changed through natural selection into inheritance by one sex alone, but in favour of this view I can discover no evidence. We know from what occurs under domestication that new characters often appear, which from the first are transmitted to one sex alone ; and by the selection of such variations there would not be the slightest difficulty in giving bright colours to the males alone, and at the same time or subsequently, dull colours to the females alone. In this manner the females of some butterflies and moths have, it is probable, been rendered inconspicuous for the sake of protection, and widely different from their males. I am, however, unwilling without distinct evidence to admit that two complex processes of selection, each requiring the transference of new characters to one sex alone, have been carried on with a multitude of species, — that the males have been rendered moie brilliant by beating their rivals, and the females more dull-coloured by having escaped from their enemies. The male, for instance, of the common brimstone butterfly (Gonepteryx), is of a far more intense yellow than the female, though she is equally conspicuous ; and it does not seem probable that she specially acquired her pale tints as a protec- tion, though it is probable that the male acquired his bright colours as a sexual attraction. The female of Anthocharis mr- damines does not possess the beautiful orange wing-tips of the male ; consequently she closely resembles the white butterflies (Pieris) so common in our gardens ; but we have no evidence that this resemblance is beneficial to her. As, on the other hand, she resembles both sexes of several other species of the genus inhabiting various quarters of the world, it is probable that she has simply retained to a large extent her primordial colours. Finally, as we have seen, various considerations lead to the conclusion that with the greater number of brilliantly-coloured Lepidoptera it is the male which has been chiefly modified through sexual selection; the amount of difference between Chap. XI. Butterflies and Moths. 323 the sexes mostly depending on the form of inheritance which has prevailed. Inheritance is governed by so many unknown laws or conditions, that it seems to us to act in a capricious manner j28 and we can thus, to a certain extent, understand how it is that with closely allied species the sexes either differ to an astonishing degree, or are identical in colour. As all the suc- cessive steps in the process of variation are necessarily trans- mitted through the female, a greater or less number of such steps might readily become developed in her ; and thus we can understand the frequent gradations from an extreme difference to none at all between the sexes of allied species. These cases of gradation, it may be added, are much too common to favour the supposition that we here see females actually undergoing the process of transition and losing their brightness for the sake of protection ; for we have every reason to conclude that at any one time the greater number of species are in a fixed condition. Mimicry, — This principle was first made clear in an admirable paper by Mr. Bates,29 who thus threw a flood of light on many obscure problems. It had previously been observed that certain butterflies in S. America belonging to quite distinct families, resembled the Heliconidae so closely in every stripe and shade of colour, that they could not be distinguished save by an ex- perienced entomologist. As the HeliconidsB are coloured in their usual manner, whilst the others depart from the usual colouring of the groups to which they belong, it is clear that the latter are the imitators, and the Heliconidae the imitated. Mr. Bates further observed that the imitating species are com- paratively rare, whilst the imitated abound, and that the two sets live mingled together. From the fact of the Heliconidae being conspicuous and beautiful insects, yet so numerous in individuals and species, he concluded that they must be pro- tected from the attacks of enemies by some secretion or odour ; and this conclusion has now been amply confirmed,30 especially by Mr. Belt. Hence Mr. Bates inferred that the butterflies which imitate the protected species have acquired their present marvellously deceptive appearance through variation and natural selection, in order to be mistaken for the protected kinds, and tiius to escape being devoured. No explanation is here attempted of the brilliant colours of the imitated, but only of the imitating butterflies. We must account for the colours of the former in the same general manner, as in the cases previously discussed 24 * The Variation of Animals and xxiii. 1862, p. 495. Plants under Domestication,' vol. ii: 30 * Prcc. Ent. Soc* Dec. Srt^ chap. xii. p. 17. 1866, p. xlv. ?* 4 Transact. Linn. Soc* vol. i2 , 324 The Descent of Man. Pari II, in this chapter. Since the publication of Mr. Bates' paper, similar and equally striking facts have been observed by Mr. Wallace in the Malayan region, by Mr. Trimen in South Africa, and by Mr. Biley in the United States.81 As some writers have felt much difficulty in understanding how the first steps in the process of mimicry could have been effected through natural selection, it may be well to remark that the process probably commenced long ago between forms not widely dissimilar in colour. In this case even a slight variation would be beneficial, if it rendered the one species more like the other ; and afterwards the imitated species might be modi- fied to an extreme degree through sexual selection or other means, and if the changes were gradual, the imitators might easily be led along the same track, until they differed to an equally extreme degree from their original condition ; and they would thus ultimately assume an appearance or colouring wholly unlike that of the other members of the group to which they belonged. It should also be remembered that many species of Lepidoptera are liable to considerable and abrupt variations in colour. A few instances have been given in this chapter ; and many more may be found in the papers of Mr. Bates and Mr. Wallace. With several species the sexes are alike, and imitate the two sexes of another species. But Mr. Trimen gives, in the paper already referred to, three cases in which the sexes of the imitated ■form differ from each other in colour, and the sexes of the imitating form differ in a like manner. Several cases have also been recorded where the females alone imitate brilliantly- coloured and protected species, the males retaining "the " normal aspect of their immediate congeners." It is here obvious that the successive variations by which the female has been modified have been transmitted to her alone. It is, however, probable that some of the many successive variations would have been transmitted to, and developed in, the males had not such males been eliminated by being thus rendered less attractive to the females; so that only those variations were preserved which were from the first strictly limited in their transmission to the female sex. We have a partial illus- tration of these remarks in a statement by Mr. Belt;32 that 31 Wal -ace, « Transact. Linn. Soc* 163-168. This latter essay is valu- vol. xxv. 1865, p. 1 ; also ' Transact, able, as Mr. Riley here discusses all Ent. Sqc' vol. iv. (3rd series), 1867, the objections which have been p. 301. Trimen, * Linn. Transact.' raised against Mr. Bates' theory, vol. xxvi. 1869, p. 497. Riley, 82 * The Naturalist in ^caiagnn, ♦Third Annual Report on the Noxi- 1874, p. 385. •us Insects of Missouri,' 1871, pp- oiur. XI. Butterflies and Moths. 325 the males of some of the Leptalides, which imitate protected species, still retain in a concealed manner some of their original characters. Thus in the males " the upper half of the lower " wing is of a pure white, whilst all the rest of the wings is " barred and spotted with black, red and yellow, like the species " they mimic. The females have not this white patch, and the " males usually conceal it by covering it with the upper wing, " so that I cannot imagine its being of any other use to them " than as an attraction in courtship, when they exhibit it to the " females, and thus gratify their deep-seated preference for the " normal colour of the Order to which the Leptalides belong." Bright Colours of Caterpillars. — Whilst reflecting on the beauty of many butterflies, it occurred to me that some cater- pillars were splendidly coloured ; and as sexual selection could not possibly have here acted, it appeared rash to attribute the beauty of the mature insect to this agency, unless the bright colours of their larvae could be somehow explained. In the first place, it may be observed that the colours of caterpillars not stand in any close correlation with those of the mature insect. Secondly, their bright colours do not serve in any ordinary manner as a protection. Mr. Bates informs me, as an instance of this, that the most conspicuous caterpillar which he ever beheld (that of a Sphinx) lived on the large green leaves of a tree on the open llanos of South America ; it was about four inches in length, transversely banded with black and yellow, and with its head, legs, and tail of a bright red. Hence it caught the eye of any one who passed by, even at the distance of many yards, and no doubt that of every passing bird. I then applied to Mr. Wallace, who has an innate genius foi solving difficulties. After some consideration he replied : " Most " caterpillars require protection, as may be inferred from some " kinds being furnished with spines or irritating hairs, and " from many being coloured green like the leaves on which they " feed, or being curiously like the twigs of the trees on which they " live." Another instance of protection, furnished me by Mr. J. Mansel Weale, may be added, namely, that there is a caterpillar of a moth which lives on the mimosas in South Africa, and fabricates for itself a case quite indistinguishable from the surrounding thorns. From such considerations Mr. Wallace thought it probable that conspicuously-coloured caterpillars were protected by having a nauseous taste ; but as their skin is extremely tender, and as their intestines readily protrude from a wound, a slight peck from the beak of a bird would be as fatal to them as if they had been devoured. Hence, as 326 The Descent of Man. Part Li Mr. Wallace remarks, " distastefulness alone would be insufficient " to protect a caterpillar unless some outward sign indicated to " its would-be destroyer that its prey was a disgusting morsel." Under these circumstances it would be highly advantageous to a caterpillar to be instantaneously and certainly recognised as unpalatable by all birds and other animals. Thus the most gaudy colours would be serviceable, and might have been gained by variation and the survival of the most easily-re- cognised individuals. This hypothesis appears at first sight very bold, but when it was brought before the Entomological Society ^ it was supported by various statements ; and Mr. J. Jenner Weir, who keeps a large number of birds in an aviary, informs me that he has made many trials-, and finds no exception to the rule, that ali caterpillars of nocturnal and retiring habits with smooth skins, all of a green colour, and ali which imitate twigs, are greedily devoured by his birds. The hairy and spinose kinds are invariably rejected, as were four conspicuously-coloured species. When the birds rejected a caterpillar, they plainly shewed, by shaking their heads, and cleansing their beaks, that they were disgusted by the taste.84 Three conspicuous kinds of cater- pillars and moths were also given to some lizards and frogs, by Mr. A. Butler, and were rejected, though other kinds were eagerly eaten. Thus the probability of Mr. Wallace's view is confirmed, namely, that certain caterpillars have been made conspicuous for their own good, so as to be easily recognised by their enemies, on nearly the same principle that poisons are sold in coloured bottles by druggists for the good of man. We cannot, however, at present thus explain the elegant diversity in the colours of many caterpillars ; but any species which had at some former period acquired a dull, mottled, or striped appear- ance, either in imitation of surrounding objects, or from the direct action of climate, &c, almost certainly would not become uniform in colour, when its tints were rendered intense and bright; for in order to make a caterpillar merely conspicuous, there would be no selection in any definite direction. Summary and Concluding Remarks on Insects, — Looking back 83 'Proc. Entomolog. Soc.' Dec. analogous facts in the * Third An- 3rd, 1866, p. xlv., and March 4th, nual Report on the Noxious Insecu 1867, p. Ixxx. of Missouri/ 1871, p. 148. Some 34 See Mr. J. Jenner Weir's opposed cases are, however, given by paper on Insects and Insectivorous Dr. Wallace and M. H. d'Orville; Birds, in * Transact. Ent. Soc* 1869, see * Zoological Record/ 1869, p. p. 21 ; also Mr. Butler's paper, 549. ibid. p. 27. Mr. Riley has give» Osap. XI. Summary on Insects. 327 to the several Orders, we see that the sexes often differ in various characters, the meaning of which is not in the least understood. The sexes, also, often differ in their organs of sense and means of locomotion, so that the males may quickly discover and reach the females. They differ still oftener in the males possessing diversified contrivances for retaining the females when found. We are, however, here concerned only in a secondary degree with sexual differences of these kinds. In almost all the Orders, the males of some species, even of weak and delicate kinds, are known to be highly pugnacious ; and some few are furnished with special weapons for fighting with their rivals. But the law of battle does not prevail nearly so widely with insects as with the higher animals. Hence it probably arises, that it is in only a few cases that the males have been rendered larger and stronger than the females. On the contrary, they are usually smaller, so that they may be developed within a shorter time, to be ready in large numbers for the emergence of the females. In two families of the Homoptera and in three of the Orthop- tera, the males alone possess sound-producing organs in an efficient state. These are used incessantly during the breeding- season, not only for calling the females, but apparently for unarming or exciting them in rivalry with other males. No one who admits the agency of selection of any kind, will, after reading the above discussion, dispute that these musical instru- ments have been acquired through sexual selection. In four other Orders the members of one sex, or more commonly of both sexes, are provided with organs for producing various sounds, which apparently serve merely as call-notes. When both sexes are thus provided, the individuals which were able to make the loudest or most continuous noise would gain partners before those which were less noisy, so that their organs have probably been gained through sexual selection. It is instructive to reflect on the wonderful diversity of the means for producing sound, possessed by the males alone, or by both sexes, in no less than six Orders. We thus learn how effectual sexual selection has been in leading to modifications which sometimes, as with the Homoptera, relate to important parts of the organisation. From the reasons assigned in the last chapter, it is probable that the great horns possessed by the males of many Lamel- licorn, and some other beetles, have been acquired as ornaments. From the small size of insects, we are apt to undervalue their appearance. If we could imagine a male Chalcosoma (fig. 16), with its polished bronzed coat of mail, and its vast complex 328 The Descent of Man. Taut It horns, magnified to the size of a horse, or even of a dog, it would be one of the most imposing animals in the world. The colouring of insects is a complex and obscure subject. "When the male differs slightly from the female, and neither are brilliantly-coloured, it is probable that the sexes have varied in a slightly different manner, and that the variations have been transmitted by each sex to the same, without any benefit or evil thus accruing. When the male is brilliantly-coloured and differs conspicuously from the female, as with some dragon-flies and many butterflies, it is probable that he owes his colours to sexual selection ; whilst the female has retained a primordial or very ancient type of colouring, slightly modified by the agencies before explained. But in some cases the female has apparently been made obscure by variations transmitted to her alone, as a means of direct protection ; and it is almost certain that she has sometimes been made brilliant* so as to imitate other protected species inhabiting the same district. When the sexes resemble each other and both are obscurely coloured, there is no doubt that they have been in a multitude of cases so coloured for the sake of protection. So it is in some instances when both are brightly-coloured, for they thus imitate protected species, or resemble surrounding objects such as flowers; or they give notice to their enemies that they are unpalatable. In other cases in which the sexes resemble each other and are both brilliant, especially when the colours are arranged for display, we may conclude that they have been gained by the male sex as an attraction, and have been transferred to the female. We are more especially led to this conclusion whenever the same type of coloration prevails throughout a whole group, and we find that the males of some species differ widely in colour from the females, whilst others differ slightly or not at all, with intermediate gradations connecting these extreme states. In the same manner as bright colours have often been partially transferred from the males to the females, so it has been with the extraordinary horns of many Lamellicorn and some other beetles. So again, the sound-producing organs proper to the males of the Homoptera and Orthoptera have generally been transferred in a rudimentary, or even in a nearly perfect condition, to the females ; yet not sufficiently perfect to be of any use. It is also an interesting fact, as bearing on sexual selection, that the stridulating organs of certain male OrthQptera are not fully developed until the last moult; and that the colours of certain male dragon-flies are not fully developed until some little time after their emergence from the pupal state, and when they are ready to breed. Chap. XI. Summary on Insects .. 329 Sexual selection implies that the more attractive individuals Eire preferred by the opposite sex ; and as with insects, when tne sexes differ, it is the male which, with some rare exceptions, is the more ornamented, and departs more from the type to which the species belongs ; — and as it is the male which searches eagerly for the female, we must suppose that the females habitually or occasionally prefer the more beautiful males, and that these have thus acquired their beauty. That the females in most or all the orders would have the power of rejecting any particular male, is probable from the many singular con- trivances possessed by the males, such as great jaws, adhesive cushions, spines, elongated legs, &c, for seizing the female ; for these contrivances shew that there is some difficulty in the act, so that her concurrence would seem necessary. Judging from what we know of the perceptive powers and affections of various insects, there is no antecedent improbability in sexual selection having come largely into play ; but we have as yet no direct evidence on this head, and some facts are opposed to the belief. Nevertheless, when we see many males pursuing the same female, we can hardly believe that the pairing is left to blind chance — that the female exerts no choice, and is not influenced by the gorgeous colours or other ornaments with which the male is decorated. If we admit that the females of the Homoptera and Orthoptera appreciate the musical tones of their male partners, and that the various instruments have been perfected through sexual se- lection, there is little improbability in the females of other insects appreciating beauty in form or colour, and consequently in such characters having been thus gained by the males. But from the circumstance of colour being so variable, and from its having been so often modified for the sake of protection, it is difficult to decide in how large a proportion of cases sexual selection has played a part. This is more especially difficult in those Orders, such as Orthoptera, Hymenoptera, and Coleop- tera, in which the two sexes rarely differ much in colour; for we are then left to mere analogy. With the Coleoptera, however, as before remarked, it is in the great Lamellicorn group, placed by some authors at the head of the Order, and in which we sometimes see a mutual attachment between the sexes, that we find the males of some species possessing weapons for sexual strife, others furnished with wonderful horns, many with stridu- lating organs, and others ornamented with splendid metallic tints. Hence it seems probable that all these characters have been gained through the same means, namely sexual selection. *With butterflies we have the best evidence, as the males 330 The Descent of Man. Past IL sometimes take pains to display their beautiful colours ; and we cannot believe that they would act thus, unless the display was of use to them in their courtship. When we treat of Birds, we shall see that they present in their secondary sexual characters the closest analogy with insects. Thus, many male birds are highly pugnacious, and some are furnished with special weapons for fighting with their rivals. They possess organs which are used during the breeding- season for producing vocal and instrumental music. They are frequently ornamented with combs, horns, wattles and plumes of the most diversified kinds, and are decorated with beautiful colours, all evidently for the sake of display. We shall find that, as with insects, both sexes in certain groups are equally beautiful, and are equally provided with ornaments which are usually confined to the male sex. In other groups both sexes are equally plain-coloured and unornamented. Lastly, in some few anomalous cases, the females are more beautiful than the males. We shall often find, in the same group of birds, every gradation from no difference between the sexes, to an extreme difference. We shall see that female birds, like female insects, often possess more or less plain traces or rudiments of characters which properly belong to the males and are of use only to them. The analogy, indeed, in all these respects between birds and insects is curiously close. Whatever explanation applies to the one class probably applies to the other ; and this explanation, as we shall hereafter attempt to shew in further detail, is sexual selection. CHAPTEB Xn. Secondaby Sexual Chakaoters of Fishes, Amphibians, and Eeptiles. Fishes : Courtship and battles of the males — Larger size of the females — Males, bright colours and ornamental appendages; other strange characters — Colours and appendages acquired by the males durind the breeding-season alone — Fishes with both sexes brilliantly coloured — Protective colours — The less conspicuous colours of the female cannot be accounted for on the principle of protection — Male fishes building nests, and taking charge of the ova and young. Amphibians: Dif- ferences in structure and colour between the sexes — Vocal organs. Reptiles : Chelonians — Crocodiles — Snakes, colours in some cases pro- tective— Lizards, battles of — Ornamental appendages — Strange dif- ferences in structure between the sexes — Colours — Sexual differences almost as great as with birds. We have now arrived at the great sub-kingdom of the Vertebrate, and will commence with the lowest elass* that of Fishes. The* Chap. XII. FisJies. 331 males of Plagiostomous fishes (sharks, rays) and of Chimseroid fishes are provided with claspers which serve to retain the female, like the various structures possessed by many of the lower animals. Besides the claspers, the males of many rays have clusters of strong sharp spines on their heads, and several rows along " the upper outer surface of their pectoral fins." These are present in the males of some species, which have other parts of their bodies smooth. They are only temporarily developed during the breeding-season ; and Dr. Gunther suspects that they are brought into action as prehensile organs by the doubling inwards and downwards of the two sides of the body. It is a remarkable fact that the females and not the males of some species, as of Rata clavata, have their backs studded with large hook-formed spines.1 The males alone of the capelin (Mallotus vittosus, one of Salmonidae), are provided with a ridge of closely-set, brush-like scales, by the aid of which two males, one on each side, hold the female, whilst she runs with great swiftness on the sandy beach, and there deposits her spawn.2 The widely distinct Monacanthus scopas presents a somewhat analogous structure. The male, as Dr. Gunther informs me, has a cluster of stiff, straight spines, like those of a comb, on the sides of the tail ; and these in a specimen six inches long were nearly one and a half inches in length ; the female has in the same place a cluster of bristles, which may be compared with those of a tooth-brush. In another species, M. peronii, the male has a brush like that possessed by the female of the last species, whilst the sides of the tail in the female are smooth. In some other species of the same genus the tail can be perceived to be a little roughened in the male and perfectly smooth in the female; and lastly in others, both sexes have smooth sides. The males of many fish fight for the possession of the females. Thus the male stickleback (Gasterosteus leiurus) has been de- scribed as " mad with delight," when the female comes out of her hiding-place and surveys the nest which he has made for her. " He darts round her in every direction, then to his accumulated u materials for the nest, then back again in an instant ; and as " she does not advance he endeavours to push her with his snout, '.' and then tries to pull her by the tail and side-spine to the nest."8 1 Yarrell's 'Hist, of British 1871, p. 119. Fishes/ vol. ii. 1836, pp. 417, 425, 3 See Mr. R. Warington's in- 436. Dr. Giinther informs me that teresting articles in * Annals and the spines in R. clavata are peculiar Mag. of Nat. Hist' Oct. 1852 and to the female. Nov. 1855. 8 * The American Naturalist/ April 332 The Descent of Man. Far* II The males are said to be polygamists ;4 they are extraordinarily bold and pugnacious, whilst "the females are quite pacific." Their battles are at times desperate; "for these puny com- " batants fasten tight on each other for several seconds, tumbling " over and over again, until their strength appears completely " exhausted." With the rough-tailed stickleback (O. trachurus) the males whilst fighting swim round and round each other, biting and endeavouring to pierce each other with their raised lateral spines. The same writer adds,5 " the bite of these little " furies is very severe. They also use their lateral spines with " such fatal effect, that I have seen one during a battle absolutely " rip his opponent quite open, so that he sank to the bottom and " died." When a fish is conquered, " his gallant bearing forsakes " him ; his gay colours fade away ; and he hides his disgrace "among his peaceable companions, but is for some time the " constant object of his conqueror's persecution." The male salmon is as pugnacious as the little stickleback ; and so is the male trout, as I hear from Dr. Gunther. Mr. Shaw saw a violent contest between two male salmon which lasted the whole day ; and Mr. K. Buist, Superintendent of Fisheries, informs me that he has often watched from the bridge at Perth the males driving away their rivals, whilst the females were spawning. The males " are constantly fighting and tearing each " other on the spawning-beds, and many so injure each other as " to cause the death of numbers, many being seen swimming near " the banks of the river in a state of exhaustion, and apparently " in a dying state."6 Mr. Buist informs me, that in June 1868, the keeper of the Stormontfield breeding-ponds visited the northern Tyne and found about 300 dead salmon, all of which with one exception were males ; and he was convinced that they had lost their lives by fighting. The most curious point about the male salmon is that during the breeding-season, besides a slight change in colour, " the " lower jaw elongates, and a cartilaginous projection turns " upwards from the point, which, when the jaws are closed, " occupies a deep cavity between the intermaxillary bones of the .ipper jaw." 7 (Figs. 27 and 28.) In our salmon this change of structure lasts only during the breeding-season: but in the 4 Noel Humphreys, * River Gar- experienced observer (Scrope's * Days dens,' 1857. of Salmon Fishing/ p. 60) remarks 5 Loudon's « Mag. of Nat. History/ that like the stag, the male would, vol. iii. 1830, p. 331. if he could, keep all other malts 6 4Th« Field/ June 29th, 1867. away. For Mr. Shaw's statement, see T Yarrell, * History of BritlBfl 1 Edinburgh Review/ 1843. Another Fishes/ v0). ii. 1836, p. 10. Chap. XH. Fishes. 333 Salmo lycaodon of N.-W. America the change, as Mr. J. K. Lord8 believes, is permanent, and best marked in the older males which have previously ascended the rivers. In these old males the jaw becomes developed into an immense hook-like projection, and Fig. 21. Head of male common salmon (Salmo safcw) during the breeding-season. TThis drawing, as well as all the others in the present chapter, have been executed by the well-known artist, Mr. G. Ford, from specimens in the British Museum, under the kind superintendence of Dr. Gtother.] fche teeth grow into regular fangs, often more than half an inch in length. With the European salmon, according to Mr. Lloyd,9 the temporary hook-like structure serves to strengthen and 8 < The Naturalist in Vancouver's 9 * Scandinavian Adventures,* vol Island/ vol ' 1866, p 54. i. 1854, pp. 100, 104. 334 The Descent of Man. Part IL protect the jaws, when one male charges another with wonderful violence ; but the greatly developed teeth of the male American salmon may be compared with the tusks of many male mammals, and they indicate an offensive rather than a protective purpose. Fig 23. Head of female salmon. The salmon is not the only fish in which the teeth differ in the two sexes ; as this is the case with many rays. In the thornback (ftaia clavata) the adult male has sharp, pointed teeth, directed backwards, whilst those of the female are broad and flat, and form a pavement ; so that these teeth differ in the two sexes of the same species more than is usual in distinct genera of the same family. The teeth of the male become sharp only when he is adult : whilst young they are broad and flat Chap. XII. Fishes. 335 like those of the female. As so frequently occurs with secondary sexual characters, both sexes of some species of rays (for instance JR. batis), when adult, possess sharp pointed teeth ; and here a character, proper to and primarily gained by the male, appears to have been transmitted to the offspring of both sexes. The teeth are likewise pointed in both sexes of R. maculata, but only when quite adult ; the males acquiring them at an earlier age than the females. We shall hereafter meet with analogous cases in certain birds, in which the male acquires the plumage common to*both sexes when adult, at a somewhat earlier age than does the female. With other species of rays the males even when old never possess sharp teeth, and consequently the adults of both sexes are provided with broad, flat teeth like those of the young, and like those of the mature females of the above-mentioned species.10 As the rays are bold, strong and voracious fish, we may suspect that the males require their sharp teeth for fighting with their rivals ; but as they possess many parts modified and adapted for the prehension of the female, it is possible that their teeth may be used for this purpose. In regard to size, M. Carbonnier ll maintains that the female of almost all fishes is larger than the male ; and Dr. Giinther does not know of a single instance in which the male is actually larger than the female. With some Cyprinodonts the male is not even half as large. As in many kinds of fishes the males habitually fight together, it is surprising that they have not generally become larger and stronger than the females through the effects of sexual selection. The males suffer from their small size, for according to M. Carbonnier, they are liable to be devoured by the females of their own species when carnivorous, and no doubt by other species. Increased size must be in some manner of more importance to the females, than strength and size are to the males for fighting with other males ; and this perhaps is to allow of the production of a vast number of ova. In many species the male alone is ornamented with bright colours ; or these are much brighter in the male than the female. The male, also, is sometimes provided with appendages which appoar to be of no more use to him for the ordinary purposes of life, than are the tail feathers to the peacock. I am indebted for most of the following facts to the kindness of Dr. Giinther. There is reason to suspect that many tropical fishes differ sexually in colour and structure; and there are some striking cases with our British fishes. The male Callionymus lyra 10 See YarrelPs account of the cellent figure, and p. 422, 432. rays in his * Hist, of British Fishes/ " As quoted in 'The Fanner, vol. ii. 1836, p. 416, with an ex- 1S68S p. 369. 33^ The Descent of Man. PautIL has been called the gemmeous dragonet " from its brilliant gem- " like colours." "When fresh caught from the sea the body is yellow of various shades, striped and spotted with vivid blue on the head ; the dorsal tins are pale brown with dark longitudinal bands; the ventral, caudal, and anal fins being bluish-black. The female, or sordid dragonet, was considered by Linnaeus, and by many subsequent naturalists, as a distinct species ; it is of a dingy reddish-brown, with the dorsal fin brown and the other Fig. 29. Callionymus lyra. Upper figure, male ; lower figure, female. N.B. The lower figure is more reduced than the upper. fins white. The sexes differ also in the proportional size of the head and mouth, and in the position of the eyes;12 but the most striking difference is the extraordinary elongation in the male (fig. 29) of the dorsal fin. Mr. W. Saville Kent remarks that this " singular appendage appears from my observations tc of the species in confinement, to be subservient to the same " end as the wattles, crests, and other abnormal adjuncts of u the male in gallinaceous birds, for the purpose of fascinating 12 I have drawn up this description from Yarrell's ' British Fishes.'rol. i. 1836, pp. 261 and 266* Ciiap. XII. Fishes. 337 " their mates." ls The young males resemble the adult females in structure and colour. Throughout the genus Callionymus/4 the male is generally much more brightly spotted than the female, and in several species, not only the dorsal, but the anal fin is much elongated in the males. The male of the Cottus scorpius, or sea-scorpion, is slenderer and smaller than the female. There is also a great difference in colour between them. It is difficult, as Mr. Lloyd15 remarks, " for any one, who has not seen this fish during the spawning- tc season, when its hues are brightest, to conceive the admixture " of brilliant colours with which it, in other respects so ill- " favoured, is at that time adorned." Both sexes of the Labrus mixtus, although very different in colour, are beautiful; the male being orange with bright blue stripes, and the female bright red with some black spots on the back. Fig. 30. Xipkophorus Hellerii. Upper figure, male ; lower figure, female. In the very distinct family of the CyprinodontidsB— inhabitants of the fresh waters of foreign lands— the sexes sometimes differ much in various characters. In the male of the Mollienesia petenensis,16 the dorsal fin is greatly developed and is marked 16 With respect to this and the following species I am indebted to Dr. Giinther for information: see also his paper on the * Fishes of Central America/ in ' Transact* Zoolog. Soc.' vol. vi 1868, p. 485. Z '3 * Nature,' July 1873, p. 264. 14 ' Catalogue of Acanth. Fishes In the British Museum,' by Dr. Giinther, 1861, pp. 138-151. 15 < Game Birds of Sweden/ &e„ 1887, p. 466. 3j8 The Descent of Man. IVkflt with a row of large, round, ocellated, bright-coloured spots; whilst the same fin in the female is smaller, of a different shape, and marked only with irregularly curved brown spots. In the male the basal margin of the anal fin is also a little produced and dark coloured. In the male of an allied form, the Xipho- phorus IJellerii (fig. 30), the inferior margin of the caudal fin is developed into a long filament, which, as I hear from Dr. Giinther, is striped with bright colours. This filament does not contain any muscles, and apparently cannot be of any direct use to the fish. As in the case of the Callionymus, the males whilst young resemble the adult females in colour and structure. Sexual -differences such as these may be strictly compared with those which are so frequent with gallinaceous birds.17 In a siluroid fish, inhabiting the fresh waters of South America, the Plecostomus barbatus 18 (fig. 31), the male has its mouth and inter-operculum fringed with a beard of stiff hairs, of which the female shows hardly a trace. These hairs are of the nature of scales. In another species of the same genus, soft flexible ten- tacles project from the front part of the head of the male, which are absent in the female. These tentacles are prolongations of the true skin, and therefore are not homologous with the stiff hairs of the former species ; but it can hardly be doubted that both serve the same purpose. What this purpose may be, it is difficult to conjectures ornament does not here seem probable, but we can hardly suppose* that stiff hairs and flexible filaments can be useful in any ordinary way to the males alone. In that strange monster, the JJhimcera mo?istrosa, the male has a hook- shaped bone on the top of the head, directed forwards, with its end rounded and covered with sharp spines ; in the female " this " crown is altogether absent," but what its use may be to the male is utterly unknown.19 The structures as yet referred to are permanent in the male after he has arrived at maturity ; but with some Blennies, and in another allied genus,20 a crest is developed on the head of the male only during- the breeding-season, and the body at the same time becomes more brightly-coloured. There can be little k oubt that this crest serves as a temporary sexual ornament, fot the female does not exhibit a trace of it. In other species o&the same genus both sexes possess a crest, and in at least one sproies " Dr< Giinther makes this re- Water/ July 1868, p. 377, wirfc, a mark ; Catalogue of Fishss in the figure. Many other cases coulj&e British Museum/ vol. iii. 1861, p. added of structures peculiar to ipe 141. male, of which the uses are not N* See Dr. Giinther on this genus, known. in <%oc. Zoolog. Soc.' 1868, p. 232. 20 Dr. Giinther, * Catalogue ot 19 $ Buckland, in * Land and Fishes/ vol. iii. pp. 221 and 240, Csaip.XII. *& Fishes. 339 > Fig. 31. Plecostonras barbatus. Upper figure, head of male ; lower figure, female 2 % ■ 340 The Descent of Man. C Vkwll neither sex is thus provided. In many of the Chromidse, foi instance in Geophagus and especially in Cichla, the males, as 1 hear from Professor Agassiz,21 have a conspicuous protuberance on the forehead, which is wholly wanting in the females and in the young males. Professor Agassiz adds, " I have often " observed these fishes at the time of spawning when the pro- " tuberance is largest, and at other seasons when it is totally " wanting, and the two sexes shew no difference whatever in the " outline of the profile of the head. I never could ascertain that " it subserves any special function, and the Indians on the " Amazon know nothing about its use." These protuberances resemble, in their periodical appearance, the fleshy caruncles on the heads of certain birds ; but whether they serve as ornaments must remain at present doubtful. I hear from Professor Agassiz and Dr. Giinther, that the males of those fishes, which differ permanently in colour from the females, often become more brilliant during the breeding-season. This is likewise the case with a multitude of fishes, the sexes of which are identical in colour at all other seasons of the year. The tench, roach, and perch may be given as instances. The male salmon at this season is "marked on the cheeks with " orange-coloured stripes, which give it the appearance of a " Labrus, and the body partakes of a golden orange tinge. The " females are dark in colour, and are commonly called black- " fish." B An analogous and even greater change takes place with the Salmo eriox or bull trout; the males of the char (S. umbla) are likewise at twis season rather brighter in colour than the females.23 The colours of the pike (Esox reticulatus) of the United States, especially of the male, become, during the breeding-season, exceedingly intense, brilliant, and iridescent.2* Another striking instance out of many is afforded by the male stickleback (Gasterostetts Uiurus), which is described by Mr. Warington,25 as being then "beautiful beyond description." The back and eyes of the female are simply brown, and the belly white. The eyes of the male, on the other hand, are " of the " most splendid green, having a metallic lustre like the green " feathers of some humming-birds. The throat and belly are " of a bright crimson, the back of an ashy-green, and the whole " fish appears as though it were somewhat translucent and 21 See also « A Journey in Brazil/ Mag. of Nat. Hktory/ vol. vi. 184 1, by Prof, and Mrs. Agassiz, 1868, p. p. 440. 220. S4 t "j'jjg American Agriculturist, K Tarrell, « British Fishes/ vol. 1868, p. 100. ii. 1836, pp. 10, 12, 35. « * Annals and Mag. of Nat. Hist. ** W. Thompson, in ' Annals and Oct. 1852. Chai\ XII. Fishes. 341 " glowed with an internal incandescence." After the breeding- season these colours all change, the throat and belly become of a paler red, the back more green, and the glowing tints subside. With respect to the courtship of fishes, other cases have been observed since the first edition of this book appeared, besides that already given of the stickleback. Mr. W. S. Kent says that the male of the Ldbrus mixtus, which, as we have seen, differs in colour from the female, makes " a deep hollow in the sand of the " tank, and then endeavours in the most persuasive manner to in- " duce a female of the same species to share it with him, swim- " ming backwards and forwards between her and the completed " nest, and plainly exhibiting the greatest anxiety for her to follow." The males of Cantharus lineatus become, during the breeding- season, of deep leaden-black ; they then retire from the shoal, and excavate a hollow as a nest. " Each male now mounts vigilant •' guard over his respective hollow, and vigorously attacks and " drives away any other fish of the same sex. Towards his com- " panions of the opposite sex his conduct is far different; many of " the latter are now distended with spawn, and these he endeavours " by all the means in his power to lure singly to his prepared " hollow, and there to deposit the myriad ova with which they are " laden, which he then protects and guards with the greatest care.26 A more striking case of courtship, as well as of display, by the males of a Chinese Macropus has been given by M. Carbonnier, who carefully observed these fishes under confinement.27 The males are most beautifully coloured, more so than the females. During the breeding-season they contend for tho possession of the females; and, in the act of courtship, expand their fins, which are spotted and ornamented with brightly coloured rays, in the same manner, according to M. Carbonnier, as the peacock. They then also bound about the females with much vivacity, and appear by " l'etalage de leurs vives couleurs chercher a attirer " l'attention des femelles, lesquelles ne paraissaient indifferentes " a ce manage, elles nageaient avec une molle lenteur vers les " males et semblaient se complaire dans leur voisinage." After the male has won his bride, he makes a little disc of froth by blowing air and mucus out of his mouth. He then collects the fertilised ova, dropped by the female, in his mouth ; and this caused 3£ Carbonnier much alarm, as he thought that they were going to be devoured. But the male soon deposits them in the disc of froth, afterwards guarding them, repairing the froth, and taking care of the young when hatched. I mention these par- ticulars because, as we shall presently see, there are fishes, the *» Mature/ May, 1873, p. 25. 2r 'Bull, de la Soc. d'Acclimat Paris, July 1869, a&d Jan. 1870, 34^ The Descent of Man. Paet II, males of "which hatch their eggs in their mouths ; and those who do not believe in the principle of gradual evolution might ask how could such a habit have originated ; but the difficulty is much diminished when we know that there are fishes which thus collect and carry the eggs; for if delayed by any cause in depositing them, the habit of hatching them in their mouths might have been acquired. To return to our more immediate subject. The case stands thus : female fishes, as far as I can learn, never willingly spawn except in the presence of the males ; and the males never fertilise the ova except in the presence of the females. The males fight for the possession of the females. In many species, the males whilst young resemble the females in colour ; but when adult become much more brilliant, and retain their colours throughout life. In other species the males become brighter than the females and otherwise more highly ornamented, only during the season of love. The males sedulously court the females, and in one case, as we have seen, take pains in displaying their beauty before them. Can it be believed that they would thus act to no purpose during their courtship ? And this would be the case, unless the females exert some choice and select those males which please or excite them most. If the female exerts such choice, all the above facts on the ornamentation of the males become at once intelligible by the aid of sexual selection. We have next to enquire whether this view of the bright colours of certain male fishes having been acquired through sexual selection can, through the law of the equal transmission of characters to both sexes, be extended to those groups in which the males and females are brilliant in the same, or nearly the same degree and manner. In such a genus as Labrus, which includes some of the most splendid fishes in the world — for instance, the Peacock Labrus (L. pavo), described,38 with pardonable exaggera- tion, as formed of polished scales of gold, encrusting lapis-lazuli, rubies, sapphires, emeralds, and amethysts — we may, with much probability, accept this belief; for we have seen that the sexes in at least one species of the genus differ greatly in colour. With some fishes, as with many of the lowest animals, splendid colours may be the direct result of the nature of their tissues and of the surrounding conditions, without the aid of selection of any kind. The gold-fish (Cyprinus auratus), judging from the analogy of the golden variety of the common carp, is perhaps a case in point, as it may owe its splendid colours to a single abrupt variation, due to the conditions to which this fish has been subjected under 48 Bory de Saint Vincent, in * Diet. Class. d'Hist. Nat.' torn. ix. 1826 p 151. Chap. XII. Fishes. 343 confinement. It is, however, more probable that these colonra nave been intensified through artificial selection, as this species nas been carefully bred in China from a remote period.29 Under natural conditions it does not seem probable that beings so nighly organised as fishes, and which live under such complex relations, should become brilliantly coloured without suffering .some evil or receiving some benefit from so great a change, and consequently without the intervention of natural selection. What, then, are we to conclude in regard to the many fishes, both sexes of which are splendidly coloured? Mr. Wallace30 believes that the species which frequent reefs, where corals and other brightly-coloured organisms abound, are brightly coloured in order to escape detection by their enemies ; but according to my recollection they were thus rendered highly conspicuous. In the fresh- waters of the tropics * there are no brilliantly- coloured corals or other organisms for the fishes to resemble ; yet many species in the Amazons are beautifully coloured, and many of the carnivorous Cyprinidae in India are ornamented with "bright longitudinal lines of various tints."31 Mr. M'Clel- land, in describing these fishes, goes so far as to suppose that " the peculiar brilliancy of their colours" serves as "a better " mark for king-fishers, terns, and other birds which are " destined to keep the number of these fishes in check;" but at the present day few naturalists will admit that any animal has been made conspicuous as an aid to its own destruction. It is possible that certain fishes may have been rendered conspicuous in order to warn birds and beasts of prey that they were unpalatable, as explained when treating of caterpillars ; but it is not, I believe, known that any fish, at least any fresh-water fish, is rejected from being distasteful to fish-devouring animals. On the whole, the most probable view in regard to the fishes, of which both sexes are brilliantly. coloured, is that their colours were acquired by the males as a sexual ornament, and were transferred equally, or nearly so, to the other sex. 29 Owing to some remarks on this has been " produced at Hangchow a subject, made in my work ' On the " variety called the fire-fish, from its Variation of Animals under Domesti- "intensely red colour. It is uni- oation/ Mr. W. F. Mayers (' Chinese " versally admired, and there is not Notes and Queries,' Aug. 1868, p. " a household where it is not cul- 123) has searched the ancient " tivated, in rivalry as to its colour, Chinese encyclopedias. He finds " and as a source of profit." that gold-fish were first reared in 30 * Westminster Review,' July confinement during the Sung Dy- 1867, p. 7. nasty, which commenced a.d. 960. 31 « Indian Cyprinidse/ by Mr. Jn the year 1129 these fishes M'Clelland, 'Asiatic Researches, abounded. In another place it is vol. xix. part ii, 1839, p. 230. said that since the year 1548 there 344 27'^ Descent of Man, Past H, We have now to consider whether, when the male differs in a marked manner from the female in colour or in other orna- ments, he alone has been modified, the variations being inherited by his male offspring alone; or whether the female has been specially modified and rendered inconspicuous for the sake of protection, such modifications being inherited only by the females. It is impossible to doubt that colour has been gained by many fishes as a protection : no one can examine the speckled upper surface of a flounder, and overlook its resemblance to the sandy bed of the sea on which it lives. Certain fishes, moreover, can through the action of the nervous system, change their colours in adaptation to surrounding objects, and that within a short time.32 One of the most striking instances ever recorded of an animal being protected by its colour (as far as it can bo judged of in preserved specimens), as well as by its form, is that given by Dr. Gunther33 of a pipe-fish, which, with its reddish streaming filaments, is hardly distinguishable from the sea-weed to which it clings with its prehensile tail. But the question now under consideration is whether the females alone have been modified for this object. We can see that, one sex will not be modified through natural selection for the sake of protection more than the other, supposing both to vary, unless one sex is exposed for a longer period to danger, or has less power of escaping from such danger than the other; and it does not appear that with fishes the sexes differ in these respects. As far as there is any difference, the males, from being generally smaller and from wandering more about, are exposed to greater danger than the females; and yet, when the sexes differ, the males are almost always the more conspicuously coloured. The ova are fertilised immediately after being deposited; and when this process lasts for several days, as in the case of the salmon,34 the female, during the whole time, is attended by the male. After the ova are fertilised they are, in most cases, left unprotected by both parents, so that the males and females, as far as oviposition is concerned, are equally exposed to danger, and both are equally important for the production of fertile ova ; consequently the more or less brightly-coloured individuals ot either sex would be equally liable to be destroyed or preserved, and both would have an equal influence on the colours of their offspring. Certain fishes, belonging to several families, make nests, and some of them take care of their young when hatched. Both ** G. Pouchet, L'Institut. Nov. 1, 327, pi. xiv. and xr. L871, p. 134. " Yarrell, * British Fisfce*/ to] w 'Froc. Zoolog. Soc' 1865, p. \l p, H Chap. XII.' Fishes. 34S sexes of the bright coloured Crenilabrus massa and melops wort together in building their nests with sea-weed, shells, &C.86 But the males of certain fishes do all the work, and afterwards take exclusive charge of the young. This is the case with the dull- coloured gobies,88 in which the sexes are not known to differ in colour, and likewise with the sticklebacks (Grasterosteus), in which the males become brilliantly coloured during the spawning season. The male of the smooth-tailed stickleback (G. leiurus) performs the duties of a nurse with exemplary care and vigilance during a long time, and is continually employed in gently leading back the young to the nest, when they stray too far. He courageously drives away all enemies, including the females of his own species. it would indeed be no small relief to the male, if the female, after depositing her eggs, were immediately devoured by some enemy, for he is forced incessantly to drive her from the nest.37 The males of certain other fishes inhabiting South America and Ceylon, belonging to two distinct Orders, have the extra- ordinary habit of hatching within their mouths or branchial cavities, the eggs laid by the females.88 I am informed by Professor Agassiz that the males of the Amazonian species which follow this habit, " not only are generally brighter than " the females, but the difference is greater at the spawning-season " than at any other time." The species of Geophagus act in the same manner ; and in this genus, a conspicuous protuberance becomes developed on the forehead of the males during the breeding-season. With the various species of Chromids, as Professor Agassiz likewise informs me, sexual differences in colour may be observed, " whether they lay their eggs in the " water among aquatic plants, or deposit them in holes, leaving " them to come out without further care, or build shallow nests " in the river mud, over which they sit, as our Pomotis does. " It ought also to be observed that these sitters are among the " brightest species in their respective families ; for instance, " Hygrogonus is bright green, with large black ocelli, encircled " with the most brilliant red." Whether with all the species of Chromids it is the male alone which sits on the eggs is not known. It is, however, manifest that the fact of the eggs being 85 According to the observations nals and Mag. of Nat. Hist.' Novem- of M. Gerbe ; see Giinther's * Record ber 1855. cf Zoolog. Literature/ 1865, p. M Prof. Wvman, in ' Proc. Boston \ 94. Soc. of Nat. "Hist/ Sept. 15, 1857. 86 Cuvier, * Regne Animal/ vol. Also Prof. Turner, in * Journal of J, 1829, p. 242. Anatomy and Phys.' Nov. 1, 1866, 17 See Mr. Warington's most p. 78. Dr. Giinther has likewia« interesting description of the habits described other casss, of the GasterosieHsIeiurw, in 'An- 346 The Descent of Man, Pabi II protected or unprotected by the parents, has had little or no influence on the differences in colour between the sexes. It is further manifest, in all the cases in which the males take exclusive charge of the nests and young, that the destruction of the blighter-coloured males would be far more influential on the character of the race, than the destruction of the brighter- coloured females ; for the death of the male during the period of incubation or nursing would entail the death of the young, so that they could not inherit his peculiarities; yet, in many of these very cases the males are more conspicuously coloured than the females. In most of the Lophobranchii (Pipe-fish, Hippocampi, &c.) the males have either marsupial sacks or hemispherical de- pressions on the abdomen, in which fche ova laid by the female are hatched. The males also shew great attachment to their young.39 The sexes do not commonly differ much in colour; but Dr. Giinther believes that the male Hippocampi are rather brighter than the females. The genus Solenostoma, however, offers a curious exceptional case,40 for the female is much more vividly-coloured and spotted than the male, and she alone has a marsupial sack and hatches the eggs; so that the female of Solenostoma differs from all the other Lophobranchii in this latter respect, and from almost all other fishes, in being more brightly-coloured than the male. It is improbable that this remarkable double inversion of character in the female sho#uld be an accidental coincidence. As the males of several fishes, whiGh take exclusive charge of the eggs and young, are more brightly coloured than the females, and as here the female Sole- nostoma takes the same charge and is brighter than the male, it might be argued that the conspicuous colours of that sex which is the more important of the two for the welfare of the offspring, must be in some manner protective. But from the large number of fishes, of which the males are either permanently or period- ically brighter than the females, but whose life is not at all more important for the welfare of the species than that of the female, this view can hardly be maintained. When we treat of birds we shall meet with analogous cases, where there has been a complete inversion of the usual attributes of the two sexes, and we shall then give what appears to be the probable explanation, namely, that the males have selected the more attractive females, instead of the latter having selected, in 3° Yarrell, « Hist, of British Fishes of Zanzibar/ by Col. Playfair, Fishes,* vol. ii. 1836, pp. 329, 338. 1866, p. 137, has re-examined th» *• Dr. Giinther, since publishing specimens, and has given .me the in account of this species in 'The above information. Chap. XII* Fishes 347 accordance with the usual rule throughout the animal kingdom, the more attractive males. ' . . On the whole we may conclude, that with most fishes, in which the sexes differ in colour or in other ornamental charac- ters, the males originally varied, with their variations trans- mitted to the same sex, and accumulated through sexual selection by attracting or exciting the females. In many cases, however, such characters have been transferred, either partially or completely, to the females. In other cases, again, both sexes have been coloured alike for the sake of protection ; but in no instance does it appear that the female alone has had her colours or other characters specially modified for this latter purpose. The last point which need be noticed is that fishes are known to make various noises, some of which are described as being musical. Dr. Dufosse, who has especially attended to this subject, says that the sounds are voluntarily produced in several ways by different fishes : by the friction of the pharyngeal bones — by the vibration of certain muscles attached to the swim- bladder, which serves as a resounding board — and by the vibra- tion of the intrinsic muscles of the swim-bladder. By this latter means the Trigla produces pure and long-drawn sounds which range over nearly an octave. But the most interesting case for us is that of two species of Ophidium, in which the males alone are provided with a sound-producing apparatus, consisting of small movable bones, with proper muscles, in connection with the swim-bladder.41 The drumming of the Umbrinas in the European seas is said to be audible from a depth of twenty fathoms ; and the fishermen of Eochelle assert " that the males " alone make the noise during the spawning-time ; and that it " is possible by imitating it, to take them without bait."42 From this statement, and more especially from the case of Ophidium, it is almost certain that in this, the lowest class of the Yerte- brata, as with so many insects and spiders, sound-producing instruments have, at least in some cases, been developed through sexual selection, as a means for bringing the sexes together. 41 ' Comptes Rendus.' Tom. xlvi. the Dutch translation of this work 1858, p. 353. Tom. xlvii. 1858, p. (vol. ii., p. 36), gives some further 916. Tom. liv. 1862, p. 393. The particulars on the sounds made by noist; made by the Umbrinas {Scwsna fishes. aquild), is said by some authors to 42 The Rev. C. Kingsley, in be more like that of a flute or organ, ' Nature/ May 1870, p. 40. than drumming : Dr. Zouteveen, in 348 The Descent of Man, Part II. Amphibians. Urodela. — I will begin with the tailed amphibians. The sexes of salamanders or newts often differ much both in colour and structure. In some species prehensile claws are developed on the fore-legs of the males during the breeding-season : and at this season in the male Triton palmipes the hind-feet are pro- vided with a swimming-web, which is almost completely absorbed during the winter; so that their feet then resemble Fig. 32. Triton cristatus (half natural size, from BU's « British Reptiles ')• Upper figure, male during the breeding-season; lower figure, female. those of the female.43 This structure no doubt aids the male in his eager search and pursuit of the female. Whilst courting her he rapidly vibrates the end of his tail. With our common newts (Triton punctatm and cristatus) a deep, much indented crest is developed along the back and tail of the male during the breeding-season, which disappears during the winter. Mr. St. George Mivart informs me that it is not furnished with muscles, and therefore cannot be used for locomotion. As during the season of courtship it becomes edged with bright colours, there can hardly be a doubt that it is a masculine ornament. In many species the body presents strongly contrasted, though lurid tints, and these become more vivid during the breeding- season. The male, for instance, of our common little newt (Triton punctatus) is "brownish-grey above, passing into yellow «3 Bell, ' History of British Reptiles,' 2nd edit. 1849, pp. 156-159, Chap. XII Amphibians, 349 " beneath, which in the spring becomes a rich bright orange, " marked everywhere with round dark spots." The edge of the crest also is then tipped with bright red or violet The female is usually of a yellowish-brown colour with scattered brown dots, and the lower surface is often quite plain.*4 The young are obscurely tinted. The ova are fertilised during the act of deposition, and are not subsequently tended by either parent. We may therefore conclude that the males have acquired their strongly-marked colours and ornamental appendages through sexual selection ; these being transmitted either to the male offspring alone, or to both sexes. Anura or Batrachia, — With many frogs and toads the colours evidently serve as a protection, such as the bright green tints of tree-frogs and the obscure mottled shades of many terrestrial species. The most conspicuously-coloured toad whieh I ever saw, the Phryniwus nigricans ,45 had the whole upper surface of the body as black as ink, with the soles of the feet and parts of the abdomen spotted with the brightest vermilion. It crawled about the bare sandy or open grassy plains of La Plata under a scorching sun, and could not fail to catch the eye of every pass- ing creature. These colours are probably beneficial by making this animal known to all birds of prey as a nauseous mouthful. In Nicaragua there is a little frog " dressed in a bright livery " of red and blue " which does not conceal itself like most other species, but hops about during the daytime, and Mr. Belt says46 that as soon as he saw its happy sense of security, he felt sure that it was uneatable. After several trials he succeeded in tempting a young duck to snatch up a young one, but it was instantly rejected ; and the duck " went about jerking its head, " as if trying to throw off some unpleasant taste." With respect to sexual differences of colour, Dr. Giinther does not know of any striking instance either with frogs or toads ; yet he can often distinguish the male from the female, by the tints of the former being a little more intense. Nor does he know of any striking difference in external structure between the sexes, excepting the prominences which become developed during the breeding-season on the front-legs of the male, by which he is enabled to hold the female.47 It is surprising that 44 Bell, * History of British Rep- sikmmensis (Dr. Anderson, * Proc. tiles/ 2nd edit. 1849, pp. 146, 151. Zoolog. Soc.,' 1871, p. 204) has two 45 * Zoology of the Voyage of the plate-like callosities on the thorax " Beagle," * 1843. Bell, ibid. p. 49. and certain rugosities on the lingers, 46 * The Naturalist in Nicaragua/ which perhaps subserve the same en** 1874, p. 321. as the above-mentioned prominence* 47 The male alone of the Bufo 350 The Descent of Man. PaiitU these animals have not acquired more strongly-marked sexual characters; for though cold-blooded their passions are strong Dr. G-unther informs me that he has several times found an unfortunate female toad dead and smothered from having been so closely embraced by three or four males. Frogs have been observed by Professor Hoffman in Giessen fighting all day long during the breeding-season, and with so much violence, that one had its body ripped open. Frogs and toads offer 'one interesting sexual difference, namely, in the musical powers possessed by the males; but to speak of music, when applied to the discordant and overwhelming sounds emitted by male bull-frogs and some other species, seems, according to our taste, a singularly inappropriate expression. Nevertheless, certain frogs sing in a decidedly pleasing manner. Near Rio Janeiro I used often to sit in the evening to listen to a number of little Hylse, perched on blades of grass close to the water, which sent forth sweet chirping notes in harmony. The various sounds are emitted chiefly by the males during the breeding-season, as in the case of the croaking of our common frog.48 In accordance with this fact the vocal organs of the males are more highly-developed than those of the females. In some genera the males alone are provided with sacs which open into the larynx.49 For instance, in the edible frog (Bana esculenta) "the sacs are peculiar tc the males, and become, when filled " with air in the act of croaking, large globular bladders, stand- " ing out one on each side of the head, near the corners of the *f mouth." The croak of the male is thus rendered exceedingly powerful ; whilst that of the female is only a slight groaning noise.60 In the several genera of the family the vocal organs differ considerably in structure, and their development in all cases may be attributed to sexual selection. Bkptiles. Chelonia. — Tortoises and turtles do not offer well-marked sexual differences. In some species, the tail of the male is longer than that of the female. In some, the plastron or lower surface of the shell of the male is slightly concave in relation to the back of the female. The male of the mud-turtle of the United States (Chrgsemys picta) has claws on its front-feet twice as long as those of the female ; and these are used when ** Bell, * History of British *• J. Bishop, in * Todd's Cyclop. Reptiles/ 1849, p. 93. of Anat. and Phvs.' vol. iv. p. 1503 *> Bell, ibid. p. 112-114. Oil A*. £11. Reptiles. 351 the sexes unite.61 With the huge tortoise of the Galapagos Islands (Testudo nigra) the males are said to grow to a larger size than the females: during the pairing-season, and at no other time, the male utters a hoarse bellowing noise, which can be heard at the distanco of more than a hundred yards ; the female, on the other hand, never uses her voice.62 With the Testudo elegans of India, it is said " that the combats " of the males may be heard at some distance, from the noise " they produce in butting against each other." M Crocodilia.— The sexes apparently do not differ in colour ; nor do I know that the males fight together, though this is pro- bable, for some kinds make a prodigious display before the females. Bartram64 describes the male alligator as striving to win the female by splashing and roaring in the midst of a lagoon, "swollen to an extent ready to burst, with its " head and tail lifted up, he spins or twirls round on the " surface of the water, like an Indian chief rehearsing his feats of war." During the season of love, a musky odour is emitted by the submaxillary glands of the crocodile, and pervades their haunts.56 ■ ■ . Ophidia. — Dr. Gunther informs me that the males are always smaller than the females, and generally have longer and slenderer tails ; but he knows of no other difference in external structure. In regard to colour, he can almost always distinguish the male from the female by his more strongly-pronounced tints ; thus the black zigzag band on the back of the male English viper is more distinctly denned than in the female. The difference js much plainer in the rattle-snakes of N. America, the male of which, as the keeper in the Zoological Gardens shewed me, can at once be distinguished from the female by having more lurid yellow about its whole body. In S. Africa the Bucephalus capensis presents an analogous difference, for the female "is " never so fully variegated with yellow on the sides as the " male." fi6 The male of the Indian Dipsas cynodon, on the other hand, is blackish-brown, with the belly partly black, whilst the female is reddish or yellowish-olive, with the belly either uniform yellowish or marbled with black. In the Tragops dispar of the same country, the male is bright green, and the "Mr.- C. J. Maynard, « The British India/ 1864, p. 7. American Naturalist,* Dec. 1869, p. ** 'Travels through Carolina, 555. &c, 1791, p. 128. 52 See ray ' Journal of Researches 65 Owen, * Anatomy of Verte- during the Voyage of the " Beagle," ' bratcs,' vol. i. 1866, p. 615. 1845, p. 384. 66 Sir Andrew Smith, ' Zoolog. of *3 Dr Gunther, « Reptiles of S. Africa : Repdlia,' 1849, pi. x. 352 The Descent of Man. PAtiT II female bronze-coloured.67 No doubt the colours of some snakes axo protective, as shewn by the green tints of tree-snakes, and the various mottled shades of the species which live in sandy places ; but it is doubtful whether the colours of many kinds, for instance of the common English snake and viper, serve to conceal them; and this is still more doubtful with the many foreign species which are coloured with extreme elegance. The colours of oertain species are very different in the adult and young states.58 During the breeding-season the anal scent-glands of snakes are in active function ;69 and so it is with the same glands in lizards, and as we have seen with the submaxillary glands of crocodiles. As the males of most animals search for the females, these odoriferous glands probably serve to excite or charm the fen ale, rather than to guide her to the spot where the male may be found. Male snakes, though appearing so sluggish, are amorous ; for many have been observed crowding round the same female, and even round her dead body. They are not known to fight together from rivalry. Their intellectual powers are higher than might have been anticipated. In the Zoological Gardens they soon learn not to strike at the iron bar with which their cages are cleaned ; and Dr. Keen of Philadelphia informs me that some snakes which he kept, learned after four or five times to avoid a noose, with which they were at first easily caught. An excellent observer in Ceylon, Mr. E. Layard, saw 15° a cobra thrust its head through a narrow hole and swallow a toad. " With this encumbrance he could not withdraw him- " self; finding this, he reluctantly disgorged the precious mor- " sel, which began to move off; this was too much for snake " philosophy to bear, and the toad was again seized, and again " was the snake, after violent efforts to escape, compelled to part " with its prey. This time, however, a lesson had been learnt, " and the toad was seized by one leg, withdrawn, and then " swallowed in triumph." The keeper in the Zoological Gardens is positive that certain snakes, for instance Crotalus and Python, distinguish him from all other persons. Cobras kept together in the same ca£? apparently feel some attachment towards each other.61 *7 Dr. A. Giinther, * Reptiles of brates,' vol. i. 1866, p. 615. British India,' Ray Soc 1864, pp. tf0 * Rambles in Ceylon,' in * Aimau 304, 308. and Mag. of Nat. Hist.' 2nd sene*, *8 Dr. Stoliczka, « Journal of vol. ix. 1852, p. 333. Asiatic Soc. of Bengal,' vol. xxxix. al Dr. Giinther, * Reptiles of 1870, pp. 205, 211. British India/ 1864, p 340. 69 Owen, 'Anatomy of Verte- Ohak XII. Reptiles. 353 It does not, however, follow because snakes have some reasoning power, strong passions and mutual affection, that they should likewise be endowed with sufficient, taste to admire brilliant colours in their partners, so as to lead to the adorn- ment of the species through sexual selection. Nevertheless, it is difficult to account in any other manner for the extreme teauty of certain species ; for instance, of the coral-snakes of S. America, which are of a rich red with black and yellow transverse bands. I well remember how much surprise I felt at the beauty of the first coral-snake which I saw gliding across a path in Brazil. Snakes coloured in this peculiar manner, as Mr. Wallace states on the autnority of Dr. Gunther,62 are found nowhere else in the world except in S. America, and here no less than four genera occur. One of these, Elaps, is venomous ; a second and widely-distinct genus is doubtfully venomous, and the two others are quite harmless. The species belonging to these distinct genera inhabit the same districts, and are so like each other, that no one "but a naturalist would distinguish the " harmless from the poisonous kinds." Hence, as Mr. Wallace believes, the innocuous kinds have probably acquired their colours as a protection, on the principle of imitation ; for they would naturally be thought dangerous by their enemies. The cause, however, of the bright colours of the venomous Elaps remains to bo explained, and this may perhaps be sexual selection. Snakes produce other sounds besides hissing. The deadly Echis carinata has on its sides some oblique rows of scales of a peculiar structure with serrated edges ; and when this snake is excited, these scales are rubbed against each other, which pro- duces " a curious prolonged, almost hissing sound." 63 With respect to the rattling of the rattle-snake, we have at last some definite information : for Professor Aughey states,64 that on twc occasions, being himself unseen, he watched from a little distance, a rattle-snake coiled up with head erect, which continued to rattle at short intervals for half an hour : and at last he saw another snake approach, and when they mot they paired. Hence he is satisfied that one of the uses of the rattle is to bring the sexes together. Unfortunately he did not ascertain whether it was the male or the female which remained stationary and called for the other. But it by no means follows from the above fact that the rattle may not be of use to these snakes in other ways, as a warning to animals which would otherwise 68 < Westminster Review/ July 1st, Soc/ 1871, p. 196. 1867, p. 32. ** * The American Naturalist,1 »W. Anderson, 'Proc. Zoolog. 1873, p. 85. 2 A 354 3H** Descent of Man, Part U , attack them. Nor can I quite disbelieve the several accounts which have appeared of their thus paralysing their prey with fear. Some other snakes also make a distinct noise by rapidly vibrating their tails against the surrounding stalks of plants ; and I have my- self heard this in the case of a Trigonocephalus in S. America. Lacertilia.— The males of some, probably of many kinds of lizards fight together from rivalry. Thus the arboreal Anolis cristatellus of S. America is extremely pugnacious : "During the " spring and early part of the summer, two adult males rarely " meet without a contest. On first seeing one another, they nod " their heads up and down three or four times, and at the same " time expanding the frill or pouch beneath the throat ; their " eyes glisten with rage, and after waving their tails from " side to side for a few seconds, as if to gather energy, they dart " at each other furiously, rolling over and over, and holding (S firmly with their teeth. The conflict generally ends in one of "* the combatants losing his tail, which is often devoured by the " victor." The male of this species is considerably larger than the female;66 and this, as far as Dr. GUnther has been able to ascertain, is the general rule with lizards of all kinds. The males alone of the Cyrtodactylus rubidus of the Andaman Islands possesses pre-anal pores ; and these pores judging from analogy probably serve to emit an odour.66 The sexes often differ greatly in various external characters. The male of the above-mentioned Anolis is furnished with a crest which runs along the back and tail, and can be erected at pleasure ; but of this crest the female does not exhibit a trace. In the Indian Cophotis ceylanica, the female has a dorsal crest, though much less developed than in the male ; and so it is, as Dr. Giinther informs me, with the females of many Iguanas, Chameleons, and other lizards. In some species, however, the crest is equally developed in both sexes, as in the Iguana tubercu- lata. In the genus Sitana, the males alone are furnished with a large throat-pouch (fig. 33), which can be folded up like a fan, and is coloured blue, black, and red ; but these splendid colours are exhibited only during the pairing-season. The female does not possess even a rudiment of this appendage. In the Anolis crtstateUus, according to Mr. Austen, the throat pouch, which is bright red marbled with yellow, is present in the female, though in a rudimental condition. Again, in certain other lizards, both sexes are equally well provided with throat pouches. Here we M Mr. N. L. Austen kept these 6S Stoliczka, ' Journal of Asiatic animals alive for a considerable Soc. of Bengal,* vol. xxxir. 1870, p. time ; see * Land and Water/ July 166. 1867, p. 0 Chap. Xlt Reptiles. 3S5 Fig. 31. Sitana minor. Male with t'»e gular pouch expanded (Irom Giintlier's * Reptiles of India ')• see with species belonging to the same group, as in so many- previous cases, the same character either confined to the males, or more largely developed in them than in the females, or again equally developed in both sexes. The little lizards of the genus Draco, which glide through the air on their rib- supported parachutes, and which in the beauty of their colours baffle description, are furnished with skinny appen- dages to the throat ." like the wattles of gallinaceous birds." These become erected when the animal is excited. They occur in both sexes, but are best developed when the male arrives at maturity, at which age the middle appendage is sometimes twice as long as the head. Most of the species like- wise have a low crest running along the neck ; and this is much more developed in the full-grown males, than in the females or young males.67 A Chinese species is said to live in pairs during the spring ; " and if " one is caught, the other falls from " the tree to the ground, and allows " itself to be captured with impu- t6 nity/'— I presume from despair.6* There are other and much more remarkable differences between the sexes of certain lizards. The male of Ceraiophora aspsra bears on the extremity of his snout an appendage half as long as the head. It is cylindrical, covered with scales, flexible, and apparently capable of erection: in the female it is quite rudimental. In a second species of the same genus a terminal scale forms a minute horn on the summit of the flexible appendage; Y ^} t?ie f°re&oing statements nificent work on the 'Reptiles ot Fig. 34. Ceratopnora Stoddartii LTpper figure, male ; lower figure, female. and quotations, in regard to Cophotis, Sitana and Draco, as well as the following facts in regard to Cerato- phora and Chamaeleon, are from Dr. Gtinther himself, or from his mag- British India,' Ray Soc. 1864, pp. 122, 130, 135. 68 Mr. Swinhoe, 'Proc. Zoolog. Soc.' 1870, p. 240. 2 a 2 SSo The Descent of Man. t*AfiT It and in a third species (C. Stoddartii, fig. 34) the whole appen- dage is converted into a horn, which is usually of a white colour, but assumes a purplish tint when the animal is excited. In the adult male of this latter species the horn is half an inch in length, but it is of quite minute size in the female and in the yoang. These appendages, as Dr. Giinther has remarked to me, may be compared with the combs of gallinaceous birds, and apparently serve as ornaments. Fig. 35. Chamseleon bifurcus. Upper figure, male ; lower figure, female. In the genus Chamseleon we come to the acme of difference between the sexes. The upper part of the skull of the male C. bifurcus (fig. 35), an inhabitant of Madagascar, is produced into two great, solid, bony projections, covered with scales like the rest of the head; and of this wonderful modification of structure the feiwle exhibits only a rudiment. Again, in Chap. XII. Reptiles. 357 Chamcelem Owenii (tig. 36), from the West Coast of Africa, the male bears on his snout and forehead three curious horns, of which the female has not a trace. These horns consist of an excrescence of bone covered with a smooth sheath, forming part of the general integu- ments of the body, so that they are identical in struc- ture with those of a bull, goat, or other sheath -horned ru- minant. Although the three horns differ so much in appearance from the two great pro- longations of the skull in C. h'furcus, we can hardly doubt that they serve the same general pur- pose in the economy of these two ani- mals. The first con- jecture, which will occur to every one, is that they are UFed by the males for fighting together; and as these animals are very quarrelsome,69 this is probably a correct view. Mr. T. \V. Wood also informs me that he once watched two individuals of C. pumilus, fighting violently on the branch of a tree ; they flung their heads about and tried to bite each other ; they then rested for a time, and afterwards continued their battle. With many lizards, the sexes differ slightly in colour, the tints and stripes of the males being brighter and more distinctly defined, than in the females. This, for instance, is the case with the above Cophotis and with the Acanthodactylus capensis of S. Africa. In a Cordylus of the latter country, the male is either much redder or greener than the female. In the Indian Calotes nigrilabris there is a still greater difference ; the lips also of the male are black, whilst those of the female are green. In our common little viviparous lizard (Zootoca vivipara) "the " under side of the body and base of the tail in the male are " bright orange, spotted with black ; in the female these parts "are pale-greyish-green without spots"70 We have seen that 69 Dr. Bucholz, * Monatsbericht ™ Bell, < History of British K. Preuss. Akad.' Jan. 1$74? p. 78. Eeptiles,' 2nd edit. 1849, p. 40. Fig 36. Cbanueleon Owenii. Upper figure, male lower figure, female. 358 The Descent of Man, Pabt II. the males alone of Sitana possess a throat-pouch ; and this is splendidly tinted with blue, black, and red. In the Proctotretus tenuis of Chile the male alone is marked with spots of blue, green, and coppery-red.71 In many cases the males retain the same colours throughout the year, but in others they become much brighter during the breeding-season; I may give as an additional instance the Calotes maria, which at this season has a bright red head, the rest of the body being green.72 Both sexes of many species are beautifully coloured exactly alike ; and there is no reason to suppose that such colours are protective. No doubt with the bright green kinds which live in the midst of vegetation, this colour serves to conceal them ; and in N. Patagonia I saw a lizard {Proctotretus multimaculatus) which, when frightened, flattened its body, closed its eyes, and then from its mottled tints was hardly distinguishable from the surrounding sand. But the bright colours with which so many lizards are ornamented, as well as their various curious appen- dages, were probably acquired by the males as an attraction, and then transmitted either to their male offspring alone, or to both sexes. Sexual selection, indeed, seems to have played almost as important a part with reptiles as with birds ; and the less conspicuous colours of the females in comparison with the males cannot be accounted for, as Mr. Wallace believes to be the case with birds, by the greater exposure of the females to danger during incubation. CHAPTER XKL Secondary Sexual Characters op Birds. Sexual differences — Law of battle — Special weapons — Vocal organs — Instrumental music — Love-antics and dances — Decorations, permanent and seasonal — Double and single annual moults — Display of ornaments by the males. Secondary sexual characters are more diversified and con- spicuous in birds, though not perhaps entailing more important changes of structure, than in any other class of animals. I shall, therefore, treat the subject at considerable length. Male birds sometimes, though rarely, possess special weapons for fighting ,l For Proctotretus see ' Zoology the Indian Calotes, see ' Reptiles of of the Voyage of the "Beagle:" British India/ by Dr Giinther, p. Keptiles,' by Mr. Bell, p. 8. For 143. the Lizards of S. Africa, see * Zoology n Giinther m * Proc. £oolog. Soc' of S. Africa: Reptiles,' by Sir 1870, p. 778, with a coloured Andrew Smith, pi. 25 and 39. For figure. Chap. XIIT, Birds. 359 with each other. They charm the female by vocal or instru- mental music of the most varied kinds. They are ornamented by all sorts of combs, wattles, protuberances, horns, air-distended sacks, top-knots, naked shafts, plumes and lengthened feathers gracefully springing from all parts of the body. The beak and naked skin about the head, and the feathers are often gorgeously coloured. The males sometimes pay their court by dancing, or by fantastic antics performed either on the ground or in the air. In one instance, at least, the male emits a musky odour, which we may suppose serves to charm or excite the female ; for that excellent observer, Mr. Bamsay,1 says of the Australian musk- duck (Biziura lobata) that " the smell which the male emits " during the summer months is confined to that sex, and in " some individuals is retained throughout the year ; I have " never, even in the breeding-season, shot a female which had " any smell of musk." So powerful is this odour during the pairing-season, that it can be detected long before the bird can be seen.2 On the whole, birds appear to be the most aesthetic of all animals, excepting of course man, and they have nearly the same taste for the beautiful as we have. This is shewn by our enjoyment of the singing of birds, and by our women, both civilised and savage, decking their heads with borrowed plumes, and using gems which are hardly more brilliantly coloured than the naked skin and wattles of certain birds. In man, however, when cultivated, the sense of beauty is manifestly a far more complex feeling, and is associated with various intellectual Before treating of the sexual characters with which we are here more particularly concerned, I may just allude to certain differences between the sexes which apparently depend on differences in their habits of life; for such cases, though common in the lower, are rare in the higher classes. Two humming-birds belonging to the genus Eustephanus, which inhabit the island of Juan Fernandez, were long thought to be specifically distinct, but are now known, as Mr. Gould informs me, to be the male and female of the same species, and they differ slightly in the form of the beak. In another genus of humming-birds (Grypus), the beak of the male is serrated along the margin and hooked at the extremity, thus differing much from that of the female. In the Neomorpha of New Zealand, there is, as we have seen, a still wider difference in the form of the beak in relation to the manner of feeding of the two sexes. Something of the same kind has been observed with the gold- 1 ' Ibis,' vol. iii-(new series) 1867, 2 Gould, ' Handbook to the Birds p. 414. of Australia/ 1865, vol. ii. p. 383. 360 Tlie Descent of Man. Part H finch (Carduelis elegant), for I am assured by Mr. J. Jenner Weir that the birdcatchers can distinguish the males by their slightly longer beaks. The flocks of males are often found feeding on the seeds of the teazle (Dipsacus), which they can reach with their elongated beaks, whilst the females more commonly feed on the seeds of the betony or Scrophularia. With a slight difference of this kind as a foundation, we can see how the beaks of the two sexes might be made to differ greatly through natural selection. In some of the above cases, however, it is possible that the beaks of the males may have been first modified in relation to their contests with other males; and that this afterwards led to slightly changed habits of life. Law of Battle. — Almost all male birds are extremely pug- nacious, using their beaks, wings, and legs for fighting together. We see this every spring with our robins and sparrows. The smallest of all birds, namely the humming-bird, is one of the most quarrelsome. Mr. Gosse8 describes a battle in which a pair seized hold of each other's beaks, and whirled round and round, till they almost fell to the ground ; and M. Montes de Oca, in speaking of another genus of humming-bird, says that two males rarely meet without a fierce aerial encounter : when kept in cages " their fighting has mostly ended in the splitting of " the tongue of one of the two, which then surely dies from " being unable to feed."* With Waders, the males of the common water-hen (Gallinula chloropus) "when pairing, fight "violently for the females: they stand nearly upright in the " water and strike with their feet." Two were seen to be thus engaged for half an hour, until one got hold of the head of the other, which would have be6n killed, had not the observer interfered; the female all the time looking on as a quiet spec- tator.6 Mr. Blyth informs me that the males of an allied bird (Gallicrex cristatus) are a third larger than the females, and are so pugnacious during the breeding-season, that they are kept by the natives of Eastern Bengal for the sake of fighting. Various other birds are kept in India for the same purpose, for instance, the bulbuls (Pycnonotus hsemorrhous) which " fight with great "spirit."6 The polygamous ruff (Machetes pugnax, fig. 37) is notorious for his extreme pugnacity ; and in the spring, the males, which are considerably larger than the females, congregate day after 3 Quoted by Mr. Gould, ' Intro- Ireland : Birds/ vol. ii. 1850, p Auction to the Trochilidae/ 1861, 327. p. 29. • Jerdon, « Birds of India/ 1863; 4 Gould, ibid. p. 52. rol. ii. p. 96. * W Thompson, * Nat. Hist, of Chap. XIIT. Law of Battle. 361 day at a particular spot, where the females propose to lay their eggs. The fowlers discover these spots by the turf being trampled somewhat bare. Here they fight very much like game- cocks, seizing each other with their beaks and striking with their wings. The great ruff of feathers round the neck is then erected, and according to Col. Montagu " sweeps the ground as ** a shield to defend the more tender parts;" and this is the only 362 The Descent of Man. Part II instance known to me in the case of birds, of any structure serving as a shield. The ruff of feathers, however, from its varied and rich colours probably serves in chief part as an orna- ment. Like most pugnacious birds, they seem always ready to fight, and when closely confined often kill each other; but Montagu observed that their pugnacity becomes greater during the spring, when the long feathers on their necks are fully developed ; and at this period the least movement by any one bird provokes a general battle.7 Of the pugnacity of web-footed birds, two instances will suffice : in Guiana " bloody fights occur *' during the breeding-season between the males of the wild " musk-duck (Cairina moschata); and where these fights have " occurred the river is covered for some distance with feathers."8 Birds which seem ill-adapted for fighting engage in fierce con- flicts ; thus the stronger males of the pelican drive away the weaker ones, snapping with their huge beaks and giving heavy blows with their wings. Male snipe fight together, "tugging " and pushing each other with their bills in the most curious " manner imaginable/' Some few birds are believed never to fight ; this is the case, according to Audubon, with one of the woodpeckers of the United States (Picus auratus), although " the " hens are followed by even half a dozen of their gay suitors." 9 The males of many birds are larger than the females, and this no doubt is the result of the advantage gained by the larger and stronger males over their rivals during many generations. The difference in size between the two sexes is carried to an extreme point in several Australian species ; thus the male musk-duck (Biziura) and the male Cincloramphus cruratis (allied to our pipits) are by measurement actually twice as large as their respective females.10 With many other birds the females are larger than the males ; and as formerly remarked, the explana- tion often given, namely, that the females have most of the work in feeding their young, will not suffice. In some few cases, as we shall hereafter see, the females apparently have acquired their greater size and strength for the sake of conquering other females and obtaining possession of the males. The males of many gallinaceous birds, especially of the poly- gamous kinds, are furnished with special weapons for fighting with their rivals, namely spurs, which can be used with fearful 7 Macgillivray, ' Hist. Brit. i. p. 191. For pelicans and snipes, Birds/ vol. iv. 1852, pp. 177-181. see vol. iii. pp. 138, 477. 8 Sir R. Schomburgk, in ' Journal 10 Gould, * Handbook of Birds or of R. Geograph. Soc' vol. xiii. 1843, Australia,* vol. i. p. 395 ; vol it p. p. 31. 383 9 'Ornithological Biography,* vol. Chap. XIII. Law of Battle, 363 effect. It has been recorded by a trustworthy writer n that in Derbyshire a kite struck at a game-hen accompanied by her chickens, when the cock rushed to the rescue, and drove his spur right through the eye and skull of the aggressor. The spur was with difficulty drawn from the skull, and as the kite though dead retained his grasp, the two birds were firmly locked together; but the cock when disentangled was very little injured. The invincible courage of the game-cock is notorious: a gentleman who long ago witnessed the brutal scene, told me that a bird had both its legs broken by some accident in the cockpit, and the owner laid a wager that if the legs could be spliced so that the bird could stand upright, he would continue fighting. This was effected on the spot, and the bird fought with undaunted courage until he received his death- stroke. In Ceylon a closely allied, wild species, the Gallus Stanleyi, is known to fight desperately "in defence of his " seraglio," so that one of the combatants is frequently found dead.12 An Indian partridge ( Ortygornis gularis), the male of which is furnished with strong and sharp spurs, is so quarrel- some, " that the scars of former fights disfigure the breast of " almost every bird you kill." 13 The males of almost all gallinaceous birds, even those which are not furnished with spurs, engage during the breeding-season in fierce conflicts. The Capercailzie and Black-cock (Tetrao urogallm and T. tetrix), which are both polygamists, have regular appointed places, where during many weeks they congregate in numbers to fight together and to display their charms before the females. Dr. W. Kovalevsky informs me that in Russia he has soon the snow all bloody on the arenas where the capercailzie ha ve fought ; and the black-cocks " make the feathers fly in every " direction/' when several " engage in a battle royal." The elder Brehm gives a curious account of the Balz, as the love- dances and love-songs of the Black-cock are called in Germany. The bird utters almost continuously the strangest noises : " he u holds his tail up and spreads it out like a fan,~he lifts up his " head and neck with all the feathers erect, and stretches his u wings from the body. Then he takes a few jumps in different " directions, sometimes in a circle, and presses the under part of " his beak so hard against the ground that the chin feathers are " rubbed off. During these movements he beats his wings and w turns round and round. The more ardent he grows the more " lively he becomes, until at last the bird appears like a frantic 11 Mr. Hewitt in the 'Poultry Nat. Hist.' vol. xiv. 1854, p. 63. Book by Tegetmeier/ 1866, p. 137* 13 Jerdon, * Birds of India./ roL '* Layard, 'Annals and Mag. of iii. p. 5" 4.* 364 The Descent of Man. Part IL " creature." At such times the black-cocks are so absorbed that they become almost blind and dea£ but less so than the caper- cailzie : hence bird after bird may be shot on the same spot, or even caught by the hand. After performing these antics the males begin to fight : and the same black-cock, in order to prove his strength over several antagonists, will visit in the course of one morning several Balz-places, which remain the same during successive years.14 The peacock with his long train appears more like a dandy than a warrior, but he sometimes engages in fierce contests : the Rev. W. Darwin Fox informs me that at some little distance from Chester two peacocks became so excited whilst fighting, that they flew over the whole city, still engaged, until they alighted on the top of St. John's tower. The spur, in those gallinaceous birds which are thus provided, is generally single ; but Polyplectron (see fig. 51, p. 397) has two or more on each leg ; and one of the Blood- pheasants (Ithayinis cruentus) has been seen with five spurs. The spurs are generally confined to the male, being represented by mere knobs or rudi- ments in the female ; but the females of the Java peacock (Pavo muticus) and, as I am informed by Mr. Blyth, of the small fire- backed pheasant (Euplocamus erythropthalmus) possess spurs. In Galloperdix it is usual for the males to have two spurs, and for the females to have only one on each leg.15 Hence spurs may be considered as a masculine structure, which has been occasion- ally more or less transferred to the females. Like most other secondary sexual characters, the spurs are highly variable, both in number and development, in the same species. Various birds have spurs on their wings. But the Egyptian goose (Chenalopex cegyptiacus) has only "bare obtuse knobs," and these probably shew us the first steps by which true spurs have been developed in other species. In the spur-winged goose, Plectropterus gambensis, the males have much larger spurs than the females ; and they use them, as I am informed by Mr. Bartlett, in fighting together, so that, in this case, the wing-spurs serve as sexual weapons ; but according to Livingstone, they are chiefly used in the defeLue of the young. The Palamedea (fig. 38) is armed with a pair of spurs on each wing ; and these are such formidable weapons, that a single blow has been known to drive a dog howling away. But it does not appear that the spurs in this case, or in that of some of the spur-winged rails, 14 Brehm, ' Must. Thierleben, Sweden,' &c, 1867, p. 79. 1867, B. iv. s. 351. Some of the ,5 Jerdon, 'Birds of India: on foregoing statements are taken from Ithaginis, vol. iii. p. 523 ; on Gano- id Lloyd, 'The Game Birds of perdix, p. 541. f Australia, this is an exception to the common vol. ii. p. 220. For the Holopteras, rule; possibly the hens may lie see Mr. Allen in the 'Ibis,' vol. v, hidden in the surrounding bushes, 1863, p. 156. as is known to be the case with the 18 Audubon, * Ornith. Biography, grey-liens in Scandinavia, and with vol. ii. p. 492 ; vol. i. pp. 4-13. other species in N. America. 19 Mr. Blyth, Land and Water, 21 * Ornithological Biography, 1867, p. 212. vol. ii. p. 275. Oka?. XG1. Law of Battle. 367 " them beyond his dominions." Generally the males try to drive away or kill their rivals before they pair. It does not, however, appear that the females invariably prefer the victorious males. I have indeed been assured by Dr. W. Kovalevsky that the female capercailzie sometimes steals away with a young male who has not dared to enter the arena with the older cocks, in the same manner as occasionally happens with the does of the red-deer in Scotland. When two males contend in presence ot a single female, the victor, no doubt, commonly gains his desire; but some of these battles are caused by wandering males trying to distract the peace of an already mated pair.22 Even with the most pugnacious species it is probable that the pairing does not depend exclusively on the mere strength and courage of the male ; for such males are generally decorated with various ornaments, which often become more brilliant during the breeding-season, and which are sedulously displayed before the females. The males also endeavour to charm or excite their mates by love-notes, songs, and antics ; and the courtship is, in many instances, a prolonged affair. Hence it is not probable that the females are indifferent to the charms of the opposite sex, or that they are invariably compelled to yield to the victorious males. It is more probable that the females are excited, either before or after the conflict, by certain males, and thus un- consciously prefer them. In the case of Tetrao umbettus, a good observer a goes so far as to believe that the battles of the males " are all a sham, performed to show themselves to the greatest " advantage before the admiring females who assemble around ; for " I have never been able to find a maimed hero, and seldom more " than a broken feather/' I shall have to recur to this subject but I may here add that with the Tetrao cupido of the United States, about a score of males assemble at a particular spot, ano strutting about, make the whole air resound with tfoeir extra ordinary noises. At the first answer from a female the maleb begin to fight furiously, and the weaker give way ; but then, according to Audubon, both the victors and vanquished search for the female, so that the females must either then exert a choice, or the battle must be renewed. So, again, with one of the field-starlings of the United States (Sturnella ludoviciana) the males engage in fierce conflicts, " but at the sight of a female u they all fly after her, as if mad." 2i 32 Brehm, * Thierleben, &c, B. 24 Audubon's ' Ornitholog. Bio* i«. 1867, p. 990. Audubon, * Ornith. graphy j' on Tetrao cupido, vol. ii« Biography,* vol. ii. p. 492. p. 492 ; on the Sturnus, vol. ii. p » 'Land and Water,' Jul/ 25th, 219. 1868, p. 14. 368 The Descent of Man. Vhm 12. Vocal and instrumental music. — With birds the voice serves to express various emotions, such as distress, fear, anger, triumph, or mere happiness. It is apparently sometimes used to excite terror, as in the case of the hissing noise made by some nestling- birds. Audubon ^ relates that a night-heron (Ardea nycticorax, Linn.) which he kept tame, used to hide itself when a cat approached, and then "suddenly start up uttering one of the *' most frightful cries, apparently enjoying the cat's alarm and " flight." The common domestic cock clucks to the hen, and the hen to her chickens, when a dainty morsel is found. The hen, when she has laid an egg, " repeats the same note very often, " and concludes with the sixth above, which she holds for a longer time ; " 26 and thus she expresses her joy. Some social birds apparently call to each other for aid ; and as they flit from tree to tree, the flock is kept together by chirp answering chirp. During the nocturnal migrations of geese and other water-fowl, sonorous clangs from the van may be heard in the darkness overhead, answered by clangs in the rear. Certain cries serve as danger' signals, which, as the sportsman knows to his cost, are understood by the same species and by others. The domestic cock crows, and the humming-bird chirps, in triumph over a defeated rival. The true song, however, of most birds and various strange cries are chiefly uttered during the breed- ing-season, and serve as a charm, or merely as a call-note, to the other sex. Naturalists are much divided with respect to the object of the singing of birds. Few more careful observers ever lived than Montagu, and he maintained that the " males of song-birds and " of many others do not in general search for the female, but, " on the contrary, their business in the spring is to perch on some '•" conspicuous spot, breathing out their full and amorous notes, " which, by instinct, the female knows, and repairs to the spot to " choose her mate." 27 Mr. Jenner "Weir informs me that this is certainly the case with the nightingale. Bechstein, who kept birds during his whole life, asserts, "that the female canary " always chooses the best singer, and that in a state of nature " the female finch selects that male out of a hundred whoso " notes please her most." 28 There can be no doubt that birds closely attend to each other's song. Mr. Weir has told me of 24 4 Ornithological Biograph.' vol. vogel,' 1840, s. 4. Mr. Harrison v. p. 601. Weir likewise writes to me : — " I 26 The Hon. Daines Barrington, " am informed that the best singing ' Philosoph. Transact.' 1773, p. 252. " males generally get a mate first, *T * Ornithological Dictionary/ "when they are bred in the sam* 1833, p. 475. " room,'* 28 'Naturgcschichtc der Stubea- Chap. XIII. Vocal Music. 369 the case of a bullfinch which had been taught to pipe a German waltz, and who was so good a performer that he cost ten guineas ; when this bird was first introduced into a room where other birds were kept and he began to sing, all the others, con- sisting of about twenty linnets and canaries, ranged themselves on the nearest side of their cages, and listened with the greatest interest to the new performer. Many naturalists believe that the singing of birds is almost exclusively " the effect of rivalry " and emulation/' and not for the sake of charming their mates. This was the opinion of Daines Barrington and White of Selborne, who both especially attended to this subject.29 Bar- rington, however, admits that " superiority in song gives to " birds an amazing ascendancy over others, as is well known to " bird-catchers." It is certain that there is an intense degree of rivalry between the males in their singing. Bird-fanciers match their birds to see which will sing longest; and I was told by Mr.Yarrellthat a first-rate bird will sometimes sing till he drops down almost dead, or according to Bechstein,30 quite dead from rupturing a vessel in the lungs. Whatever the cause maybe, male birds, as I hear from Mr. Weir, often die suddenly during the season of song. That the habit of singing is sometimes quite independent of love is clear, for a sterile, hybrid canary-bird has been de- scribed 31 as singing whilst viewing itself in a mirror, and then dashing at its own image; it likewise attacked with fury a female canary, when put into the same cage. The jealousy excited by the act of singing is constantly taken advantage of by bird-catchers; a male, in good song, is hidden and protected, whilst a stuffed bird, surrounded by limed twigs, is exposed to view. In this manner, as Mr. Weir informs me, a man has in the course of a single day caught fifty, and in one instance seventy, male chaffinches. The power and inclination to sing differ so greatly with birds that although the price of an ordinary male chaffinch is only sixpence, Mr. Weir saw one bird for which the bird-catcher asked three pounds; the test of a really good singer being that it will continue to sing whilst the cage is swung round the owner's head. That male birds should sing from emulation as well as for charming the female, is not at all incompatible ; and it might have been expected that these two habits would have concurred, like those of display and pugnacity. Some authors, however, 29 'Philosophical Transactions,' 8o ' Naturgesch. der Stubenvogel/ 1773, p. 263. White's 'Natural 1840, s. 252. Hi'story of Selborne/ 1825, vol. i. p. 31 Mr. Bold, ' Zoologist/ 1843-44, 245. p. 659. 2 B 3/0 The Descent of Man. Part IL argue that tlie song of the male cannot serve to charm the female, because the females of some few species, such as of the canary, robin, lark, and bullfinch, especially when in a state of widow- hood, as Bechstein remarks, pour forth fairly melodious strains. In some of these cases the habit of singing may be in part attributed to the females having been highly fed and confined,31 for this disturbs all the usual functions connected with the repro- duction of the species. Many instances have already been given of the partial transference of secondary masculine characters to the female, so that it is not at all surprising that the females of some species should possess the power of song. It has also been argued, that the song of the male cannot serve as a charm, be- cause the males of certain species, for instance of the robin, sing during the autumn.38 But nothing is more common than for animals to take pleasure in practising whatever instinct they follow at other times for some real good. How often do we see birds which fly easily, gliding and sailing through the air ob- viously for pleasure ? The cat plays with the captured mouse, and the cormorant with the captured fish. The weaver-bird (Ploceus), when confined in a cage, amuses itself by neatly weaving blades of grass between the wires of its cage. Birds which habitually fight during the breeding-season are generally ready to fight at all times; and the males of the capercaiJzie sometimes hold their Balzen or leks at the usual place of as- semblage during th^ autumn.34 Hence it is not at all surprising that male birds should continue singing for their own amuse- ment after the season for courtship is over. As shewn in a previous chapter, singing is to a certain extent an art, and is much improved by practice. Birds can be taught various tunes, and even the unmelodious sparrow has learnt to sing like a linnet. They acquire the song of their foster parents,85 and sometimes that of their neighbours." All the common songsters belong to the Order of Insessores, and their vocal organs are much more complex than those of most other birds ; yet it is a singular fact that some of the Insessores, such as ravens, crows, and magpies, possess the proper apparatus,37 82 D. Barrington, 'Phil. Transact.* Bechstem, ibid. s. 5. 1773, p. 262. BecfcsTOin, ' Stuben- 3fl Dureau de la Malle gives a vogel/ 1840, s. 4. curious instance (' Annales des Sc. 33 This is likewise the case with Nat/ 3rd series, Zoolog. torn. x. p. taa water-ouzel, see Mr. Hepburn 118) of some wild blackbirds in his in the 'Zoologist/ 1845-1846, p. garden in Paris, which naturally 1068. learnt a republican air from a caged 34 L. Lloyd, 'Game Birds of bird. Sweden/ 1867, p. 25. * Bishop, in * Todd's Cyclop, of Sd Barrington, ibid. p. 264. Anat. and Phys.' vol. iv. p. I4$H> Chap. XIII. Vocal Music. 37 1 though they never sing, and do not naturally modulate their voices to any great extent. Hunter asserts 38 that with the true songsters the muscles of the larynx are stronger in the males than in the females ; but with this slight exception there is no difference in the vocal organs of the two sexes, although the males of most species sing so much better and more continuously than the females. It is remarkable that only small birds properly sing. The Australian genus Menura, however, must be excepted ; for the Menura Alberti, which is about the size of a half-grown turkey, not only moc£s other birds, but " its own whistle is exceedingly " beautiful and varied." The males congregate and form " cor- roborying places," where they sing, raising and spreading their tails like peacocks, and drooping their wings.39 It is also remark- able that birds which sing well are rarely decorated with brilliant colours or other ornaments. Of our British birds, excepting the bullfinch and goldfinch, the best songsters are plain-coloured. The kingfisher, bee-eater, roller, hoopoe, woodpeckers, &c, utter harsh cries; and the brilliant birds of the tropics are hardly ever songsters.40 Hence bright colours and the power of song seem to replace each other. We can perceive that if the plumage did not vary in brightness, or if bright colours were dangerous to tho species, other means would be employed to charm the females ; and melody of voice offers one such means. In some birds the vocal organs differ greatly in the two sexes. In the Tetruo cupido (fig. 39) the male has two bare, orange- coloured sacks, one on each side of the neck; and these are largely inflated when the male, during the breeding-season, makes his curious hollow sound, audible at a great distance Audubon proved that the sound was intimately connected with this apparatus (which reminds us of the air-sacks on each side ot the mouth of certain male frogs), for he found that the sound was much diminished when one of the sacks of a tame bird was pricked, and when both were pricked it was altogether stouped. The female has " a somewhat similar, though smaller naked space u of skin on the neck ; but this is not capable of inflation." 41 The 88 As stated by Barrington in in Canada/ by Major W. Ross King, < Philosoph. Transact.' 1773, p. 262. 1866, pp. 144-146. Mr. T. W. 39 Gould, ' Handbook to the Birds Wood gives in the 'Student* of Australia,' vol. i. 1865, pp. 308- (April, 1870, p. 116) an excellent 310. See also Mr. T. W. Wood in account of the attitude aDd habits the < Student,' Anril 1870, p. 125. of this bird during its courtship. 40 See remarks to this effect in He states that the ear-tufts or neck- mould's * Introduction to the Trochi- plumes are erected, so that they lidae,* 1861, p. 22. meet over the crown of the head* *2 ' The Sportsman and Naturalist See his drawing, fig. 39. 2 B 2 372 The Descent of Man. Part II. male of another kind of grouse (Tefrao urophasianus), whilst courting the female, has his " bare yellow oesophagus inflated to " a prodigious size, fully half as large as the body ; " and he then utters various grating, deep, hollow tones. With his neck- feathers erect, his wings lowered, and buzzing on the gound, and his long pointed tail spread out like a fan, he displays a variety of grotesque attitudes. The oesophagus of the female is not in any way remarkable.42 42 Richardson, < Fauna Bor. American: Birds/ 1831, p. 359. Auduboii bid. vol. iv. p. 507. Chap. XIII. Vocal Music. 375 It seems now well made out that the great throat pouch oi the European male bustard (Otis tarda), and of at least four other species, does not, as was formerly supposed, serve to hold water, but is connected with the utterance during the breeding- Fig. 40. The Umbrella-bird or Cephalopterus ornatus male irom Brehm). season of a peculiar sound resembling "oak."43 A crow-lik& bird inhabiting South America (Cephalopterus ornatus, fig. 40) is called the umbrella-bird, from its immense top knot, formed of * 43 The following papers have been lately written on this subject r Prof. A. Newton, in the 4 Ibis/ 1862, p. 107 , Dr. Cullen, ibid. 1865, p. 145 ; Mr Flower, in * Proc. Zool. Soc.' 1865, p. 747 ; and Dr Murie, in 'Proc Zool. Soc. 1868. p. 471. In this latter paper an excellent figure is given of the male Austra* ban Bustard in full display- with the sack distended. It is a singular fact that the sack is not developed in all the males of the same species, 374 Ike descent of Man. Pabt TL bare white quills surmounted by dark-blue plumes, which it can elevate into a great dome no less than five inches in diameter, covering the whole head. This bird has on its neck a long, thin, cylindrical fleshy appendage, which is thickly clothed with scale- like blue feathers. It probably serves in part as an ornament, but likewise as a resounding apparatus ; for Mr. Bates found that it is connected " with an unusual development of the " trachea and vocal organs." It is dilated when the bird utters its singularly deep, loud and long sustained fluty note. The head- crest and neck-appendage are rudimentary in the female.44 The vocal organs of various web-footed and wading birds are extraordinarily complex, and differ to a certain extent in the two sexes. In some cases the trachea is convoluted, like a French horn, and is deeply embedded in the sternum. In the wild swan (Cygnusferus) it is more deeply embedded in the adult male, than in the adult female or young male. In the male Merganser the enlarged portion of the trachea is furnished with an additional pair of muscles.45 In one of the ducks, however, namely Anas punctata, the bony enlargement is only a little more developed in the male than in the female.46 But the meaning of these differences in the trachea of the two sexes of the Anatidse is not understood; for the male is not always the more vociferous; thus with the common duck, the male hisses, whilst the female utters a loud quack.47 In both sexes of one of the cranes (Grus virgo) the trachea penetrates the sternum, but presents " certain " sexual modifications." In the male of the black stork there is also a well-marked sexual difference in the length and curvature of the bronchi48 Highly important structures have, therefore, in these cases been modified according to sex. It is often difficult to conjecture whether the many strango cries and notes uttered by male birds during the breeding- season, serve as a charm or merely as a call to the female. The soft cooing of the turtle-dove and of many pigeons, it may be presumed, pleases the female. When the female of the wild 44 Bates, * The Naturalist on the of eight, and yet this bird (Jerdon, Amazons,* 1863, vol. ii. p. 284; * Birds of India/ vol. iii. p. 703) is "Wallace, in * Proc. Zool. Soc.' 1850, mute ; but Mr. Blyth informs me p. 206. A new species, with a still that the convolutions are not con- larger neck-appendage (C. pendu- stantly present, so that perhaps tiger), has lately been discovered, they are now tending towards see * Ibis/ vol. i. p. 457. abortion. 45 Bishop, in Todd's * Cyclop, of 48 * Elements of Comp. Anat/ by jmat. and Phys.' vol. iv. p. 1499. E. Wagner, Eng. translat. 1845, p. 46 Prof. Newton, 'Proc. Zoclog. 111. With respect to the swan, as Soc/ 1871, p. 651. given above, Yarrell's ' Hist. of 47 The spoonbill (Platalea) has British Birds/ 2nd edit. 1845, vo* Kb trachea convoluted into a figure iii. p. 193. Chap. XIII. Instrumental Musk. 375 turkey utters her call in the morning, the male answers by a note which differs from the gobbling noise made, when with erected feathers, rustling wings and distended wattles, he puffs and struts before her.49 The spel of the black-cock certainly serves as a call to the female, for it has been known to bring four or five females from a distance to a male under confinement; but as the black-cock continues his spel for hours during successive days, and in the case of the capercailzie " with an agony of " passion/' we are led to suppose that the females which are present are thus charmed.60 The voice of the common rook is known to alter during the breeding-season, and is therefore in some way sexual.61 But what shall we say about the harsh screams of, for instance, some kinds of macaws; have these birds as bad taste for musical sounds as they apparently have for colour, judging by the inharmonious contrast of their bright yellow and blue plumage ? It is indeed possible that without any advantage being thus gained, the loud voices of many male birds may be the result of the inherited effects of the continued use of their vocal organs, when excited by the strong passions of love, jealousy and rage; but to this point we shall recur when we treat of quadrupeds. We have as yet spoken only of the voice, but the males of various birds practise, during their courtship, what may be called instrumental music. Peacocks and Birds of Paradise rattle their quills together. Turkey-cocks scrape their wings against the ground, and some kinds of grouse thus produce a buzzing sound. Another North American grouse, the Tetrao umbellus, when with his tail erect, his ruffs displayed, " he shows off his finery to tbe " females, who lie hid in the neighbourhood," drums by rapidly striking his wings together above his back, according to Mr. R. Haymond, and not, as Audubon thought, by striking them against his sides. The sound thus produced is compared by some to distant thunder, and by others to the quick roll of a drum. The female never drums, " but flies directly to the place u where the male is thus engaged." The male of the Kalij- pheasant, in the Himalayas, " often makes a singular drumming " noise with his wings, not unlike the sound produced by shaking " a stiff piece of cloth." On the west coast of Africa the little black-weavers (Ploceus ?) congregate in a small party on the bushes round a small open space, and sing and glide through 49 C. L. Bonaparte, quoted m the Sweden,' &c, 1867, pp. 22, 81. 'Naturalist Library: Birds/ vol. " Jenner, * Philosnph. TraftMO* lriv. p. 126. tions,' 1824, p. 20. M L. Lioyd3 ' The Game Bird* of $76 The Descent of Man. Part II the air with quivering wings, '"' which make a rapid whirring " sound like a child's rattle/' One bird after another thus performs for hours together, but only during the courting-season. At this season and at no other time, the males of certain night-jars (Capri- mulgus) make a strange booming noise with their wings. The various species of wood-peckers strike a sonorous branch %ith their beaks, with so rapid a vibratory movement that " the head " appears to be in two places at once." The sound thus pro- duced is audible at a considerable distance, but cannot be described ; arid I feel sure that its source would never be con- jectured by any one hearing it for the first time. As this jarring sound is made chiefly during the breeding-season, it has been considered as a love-song; but it is perhaps more strictly a love-call. The female, when driven from her nest, has been observed thus to call her mate, who answered in the same manner and soon appeared. Lastly, the male Hoopoe ( Upupa epops) combines vocal and instrumental music ; for during the breeding-season this bird, as Mr. Swinhoe observed, first draws in air, and then taps the end of its beak perpendicularly down against a stone or the trunk of a tree, " when the breath being " forced down the tubular bill produces the correct sound." If the beak is not thus struck against some object, the sound is quite different. Air is at the same time swallowed, and the oesophagus thus becomes much swollen ; and this probably acts as a resonator, not only with the hoopoe, but with pigeons and other birds.62 In the foregoing cases sounds are made by the aid of structures already present and otherwise necessary ; but in the following cases certain feathers have been specially modified for the express purpose of producing sounds. The drumming, bleating, neigh- ing, or thundering noise (as expressed by different observers) made by the common snipe (Scolopax gallinago) must have sur- prised every one who has ever heard it. This bird, during the pairing-season, flies to " perhaps a thousand feet in height," and 52 For the foregoing facts see, Weavers, 'Livingstone's Expedition on Birds of Paradise, Brehm, to the Zambesi/ 1865, p. 425. On * Thierleben,' Band iii. s. 325. On . Woodpeckers, Macgillivray, * Hist. Grouse, Richardson, * Fauna Bor. of British Birds,* vol. iii. 1840, pp. Americ. : Birds,' pp. 343 and 359 ; 84, 88, 89, and 95. On the Hoopoe, Major W. Ross King, * The Sports- Mr. Swinhoe, in * Proc. Zoolog. Soc.' man in Canada,' 1866, p. 156; Mr. June 23, 1863 and 1871, p. 348 Haymond, in Prof. Cox's t Geol. On the Night-jar, Audubon, ibid. Survey of Indiana,' p. 227 ; Audu- vol. ii. p. 255, and ' American Natu- bon, * American Ornitholog. Bio- ralist,' 1873, p. 672. The English graph.' vol. i. p. 216. On the Night-jar likewise makes in the Kalij-pheasant, Jerdon, * Birds of spring a curious noise during its India,' vol. iii. p. 533. On the rapid flight. Chap. XIII. Instrumental Music, m after zig-zagging about for a time descends to the earth in a curved line, with outspread tail and quivering pinions, and surprising velocity. The sound is emitted only during this rapid descent. No one was able to explain the cause, until M. Mesves observed that on each side of the tail the outer feathers are peculiarly formed (fig. 41), having a stiff sabre-shaped shaft Fig. 41. Outer tail-feather of Scolopax gallinago (from * Proc. Zool. Soc' 1358). with the oblique barbs of unusual length, the outer webs being strongly bound together. He found that by blowing on these feathers, or by fastening them to a long thin stick and waving them rapidly through the air, he could reproduce the drumming noise made by the living bird. Both sexes are furnished with these feathers, but they are generally larger in the male than in the female, and emit a deeper note. In some species, as in S. frenaia (fig. 42), four feathers, and in S. javensis (fig. 43), no less than eight on each side of the tail are greatly modified. Different tones are emitted by the feathers of the different species when waved through the air ; and the Scolopax Wilsonii of the United States makes a switching noise whilst descending rapidly to the earth.53 In the male of the Charncepetes unicolor (a large gallinaceous bird of America) the first primary wing-feather is arched towards the tip and is much more attenuated than in the female. In an allied bird, the Penelope nigra, Mr. Salvin observed a male, which, whilst it flew downwards " with outstretched wings, gave forth '" a kind of crashing rushing noise/' like the falling of a tree.54 Fig. 42. Outer tail-feath-r of Scolopax frenata. Fig. 43. Outer tail-feather of Scolopax javensis. 63 See M. Meves' interesting paper in 'Proc. Zool. Soc.' 1858, p. 199. For the habits of the snipe, Macgillivray, < Hist. British Birds,' vol. iv. p. 371. For the American snipe, Capt. Blakiston, * Ibis,* vol. r. 1863, p. 131. 54 Mr. Salvin, in « Proc. Zool. Soc/ 1867, p. 160. I am much in- debted to this distinguished orni- thologist for sketches of the feathers of the Chama?petes, and for other information. 37* The Descent of Man, Part II. Fig. 44. Primary wing-feather of a Humming-bird, the Sdasphorus pla- tycercus (from a sketch by Mr. Sal- vin). Upper figure, that of male; lower figure, corresponding feather of female. The male alone of one of the Indian bustards (Sypheotides auritus) has its primary wing-feathers greatly acuminated; and the male of an allied species is known to make a humming noise whilst courting the female.55 In a widely different group of birds, namely Humming-birds, the males alone of certain kinds have either the shafts of their primary wing- feathers broadly dilated, or the webs abruptly excised towards the extremity. The male, for in- stance, of Selasphorus platycercus, when adult, has the first primary wing-feather (fig. 44), thus excised. Whilst flying from flower to flower he makes " a shrill, almost whist- ling noise ;"66 but it did not appear to Mr. Salvin that the noise was intentionally made. Lastly, in several species of a sub-genus of Pipra or Manakin, the males, as described by Mr. Sclater, have their secondary wing- feathers modified in a still more remarkable manner. In the brilliantly-coloured P. deliciosa the first three secondaries are thick-stemmed and curved towards the body; in the fourth and fifth (fig. 45, a) the change is greater; and in the sixth and seventh (&, c) the shaft " is thickened to an extraordinary degree, " forming a solid horny lump." The barbs also are greatly changed in shape, in comparison with the corresponding feathers (d> e, /) in the female. Even the bones of the wing, which support these singular feathers in the male, are said by Mr. Praser to be much thickened. These little birds make an extraordinary noise, the first " sharp note being not unlike the " crack of a whip." 67 The diversity of the sounds, both vocal and instrumental, made by the males of many birds during the breeding-season, and the diversity of the means for producing such sounds, are highly remarkable. We thus gain a high idea of their importance for sexual purposes, and are reminded of the con- clusion arrived at as to insects. It is not difficult to imagine the steps by which the notes of a bird, primarily used as a mere call or for some other purpose, might have been improved 55 Jerdon, * Birds of India,' vol. iii. pp. 618, 621. 56 Gould, 'Introduction to the Trochilidae/ 1861, p. 49. Salvin, Jerdon, ' Birds of folia,' vol. Birds,' vol. xiv. p. 166. Hi. p. 620. «» Sclater, in the 'Ibis/ vol. vi '• < Proc.Zoolog.Soc/lS73, p. 429 Chap. XIII. Decoration. ^85 A.gain, the barbs of the feathers in various widely-distinct birds are filamentous or plumose, as with some herons, ibises, tarda of paradise, and Gallinacese. In other cases the barbs disappear, leaving the shafts bare from end to end ; and these in the tail of the Paradisea apoda attain a length of thirty-four inches:71 in P. Papuana (fig. 47) they are much shorter and thin. Smaller feathers when thus denuded appear like bristles, as on the breast of the turkey-cock. As any fleeting fashion in dress comes to be admired by man, so with birds a change of almost any kind in the structure or colouring of the feathers in the male appears to have been admired by the female. The fact of the feathers in widely distinct groups, having been modified in an analogous manner, no doubt depends primarily on all the feathers having nearly the same structure and manner of development, and consequently tending to vary in the same manner. "We often see a tendency to analogous variability in the plumage of our domestic breeds belonging to distinct species. Thus top-knots have appeared in several species. In an extinct variety of the turkey, the top-knot consisted of bare quills surmounted with plumes of down, so that they somewhat resembled the racket-shaped feathers above described. In certain breeds of the pigeon and fowl the feathers are plumose, with some tendency in the shafts to be naked. In the Sebas- topol goose the scapular feathers are greatly elongated, curled, or even spirally twisted, with the margins plumose.** In regard to colour hardly anything need here be said, for every one knows how splendid are the tints of many birds, and how harmoniously they are combined. The colours are often metallic and iridescent. Circular spots are sometimes sur- rounded by one or more differently, shaded zones, and are thus converted into ocelli. Nor need much be said on the wonderful difference between the sexes of many birds. The common peacock offers a striking instance. Female birds of paradise are obscurely coloured and destitute of all ornaments, whilst the males are probably the most highly decorated of all birds, and in so many different ways, that they must be seen to be appre- ciated. The elongated and golden-orange plumes which spring from beneath the wings of the Paradisea apoda, when vertically erected and made to vibrate, are described as forming a sort oi halo, in the centre of which the head " looks like a little emerald " sun with its rays formed by the two plumes."73 In another 71 Wallace, in ' Annals and Mag. 72 See my work on ' The Variation of Nat. Hist.' vol. xx. 1857, p. 416 of Animals and Plants under Dome»- and in his * Malay Archipelago, tication,' vol. i. pp. 289, 293. vol. ii. 1869, p. 300." " Quoted from M. de Lafresnaye 2 g 386 The Descent of Man. PabtIT most beautiful species the head is bald, " and of a rich cobalt " blue, crossed by several lines of black velvety feathers."74 in 'Annals and Mag. of Nat. Hist/ * Malay Archipelago/ vol. xih. 1854, p. 157: see also Mr. 7* Wallace, 'The Malay Archi- Wallace's much fuller account in pelage/ vol. ii. 1869, p. 405, vol. xx. 1857, p. 412, and in his Chap. XIII. Decoration. 387 Male humming-birds (figs. 48 and 49) almost vie with birds of paradise in their beauty, as every one will admit who has seen Mr. Gould's splendid volumes, or his rich collection. It is very remarkable in how many different ways these birds are orna- mented. Almost every part of their plumage has been taken advantage of, and modified; and the modifications have been 1% 48. Lophornis ornatus, male and female (from Brehm). 2 c 2 338 The Descent of Man. Pae* IL carried, as Mr. Gould shewed me, to a wonderful extreme in some species belonging to nearly every sub-group. Such, cases are curiously like those which we see in our fancy breeds, reared by man for the sake of ornament: certain individuals originally varied in one character, and other individuals of the fig. 49. Spathura underwood!, male and female (from Brebm). Chap. XIII. Decoration, jgg same species in other characters ; and these have been seized on by man and much augmented— as shewn by the tail of the fan- tail-pigeon, the hood of the jacobin, the beak and wattle of the carrier, and so forth. The sole difference between these cases is that in the one, the result is due to man's selection, whilst in the other, as with humming-birds, birds of paradise, &c, it is due to the selection by the females of the more beautiful males. I will mention only one other bird, remarkable from the ex- treme contrast in colour between the sexes, namely the famous bell-bird (Ghasmorhynchus niveus) of S. America, the note of which can be distinguished at the distance of nearly three miles, and astonishes everyone when first hearing it. The male is pure white, whilst the female is dusky-green ; and white is a very rare colour in terrestrial species of moderate size and in- offensive habits. The male, also, as described by Waterton, has a spiral tube, nearly three inches in length, which rises from the base of the beak. It is jet-black, dotted over with minute downy feathers. This tube can be inflated with air, through a communication with the palate; and when not inflated hangs down on one side. The genus consists of four species, the males of which are very distinct, whilst the females, as described by Mr. Sclater in a very interesting paper, closely resemble each other, thus offering an excellent instance of the common rule that within the same group the males differ much more from each other than do the females. In a second species (C. nudi- collis) the male is likewise snow-white, with the exception of a large space of naked skin on the throat and round the eyes, which during the breeding-season is of a fine green colour. In a third species (C. tricarunculatus) the head and neck alone of the male are white, the rest of the body being chesnut-brown, and the male of this species is provided with three filamentous projections half as long as the body— one rising from the base of the beak, and the two others from the corners of the mouth.™ The coloured plumage and certain other ornaments of the adult males are either retained for life, or are periodically re- newed during the summer and breeding-season. At this same season the beak and naked skin about the head frequently change colour, as with some herons, ibises, gulls, one of the bell-birds just noticed, &c. In the white ibis, the cheeks, the inflatable skin of the throat, and the basal portion of the beak then become crimson.76 In one of the rails, Qallicrex cristatus, a 75 Mr. Sclater, * Intellectual Ob- plate, in the ' Ibis,* 1865, p. 90. (server,* Jan. 1867.: 'Waterton's 78 'Land and Water/ 3867, i> Wanderings,' p. 118. See aJ so Mr. 394. Salvin'g interesting paper, with a 390 The Descent of Man, Part IL large red caruncle is developed during this period on the head of the male. So it is with a thin horny crest on the beak of one of the pelicans, P. erythrorhynchus ; for after the breeding- season, these horny crests are shed, like horns from the heads of stags, and the shore of an island in a lake in Nevada was found covered with these curious exuvia).77 Changes of colour in the plumage according to the season depend, firstly on a double annual moult, secondly on an actual change of colour in the feathers themselves, and thirdly on their dull-coloured margins being periodically shed, or on these three processes more or less combined. The shedding of the de- ciduary margins may be compared with the shedding of their down by very young birds; for the down in most cases arises from the summits of the first true feathers.78 With respect to the birds which annually undergo a double moult, there are, firstly, some kinds, for instance snipes, swallow- plovers (Glareolse), and curlews, in which the two sexes resemble each other, and do not change colour at any season. I do not know whether the winter plumage is thicker and warmer than th® summer plumage, but warmth seems the most probable end attained of a double moult, where there is no change of colour. Secondly, there are birds, for instance, certain species of Totanus and other Grallatores, the sexes of which resemble each other, but in which the summer and winter plumage differ slightly in colour. The difference, however, in these cases is so small that it can hardly be an advantage to them ; and it may, perhaps, be attributed to the direct action of the different conditions to which the birds are exposed during the two seasons. Thirdly, there are many other birds the sexes of which are alike, but which are widely different in their summer and winter plumage. Fourthly, there are birds, the sexes of which differ from each other in colour ; but the females, though moulting twice, retain the same colours throughout the year, whilst the males undergo a change of colour, sometimes a great one, as with certain bustards. Fifthly and lastly, *here are birds the sexes of which differ from each other in both their summer and winter plumage ; but the male undergoes a greater amount of change at each recurrent season than the female— of which the ruff {Machetes pugnax) offers a good instance. With respect to the cause or purpose of the differences in colour between the summer and winter plumage, this may in some instances, as with the ptarmigan,79 serve during both " Mr. D. G. Elliot, in « Proc. edited by P L. Sclater. Ray Soc Zool. Soc/ 1869, p. 589. 1867. p. 14. n Xi^zsch's ' Pterylography/ '* The brown mottled summej Chap. XIIL Double A nnual Moult 39 1 seasons as a protection. When the difference between the two plumages is slight, it may perhaps be attributed, as already remarked, to the direct action of the conditions of life. But with many birds there can hardly be a doubt that the summer plumage is ornamental, even when both sexes are alike. Wo may conclude that this is the case with many herons, egrets, &c, for they acquire their beautiful plumes only during the breeding-season. Moreover, such plumes, top-knots, &c, though possessed by both sexes, are occasionally a little more developed in the male than in the female; and they resemble the plumes and ornaments possessed by the males alone of other birds. It is also known that confinement, by affecting the reproductive system of male birds, frequently checks the development of their secondary sexual characters, but has no immediate influence on any other characters ; and I am informed by Mr. Bartlett that eight or nine specimens of the Knot (Tringa canutus) re- tained their unadorned winter plumage in the Zoological Gardens throughout the year, from which fact we may infer that the summer plumage though common to both sexes partakes of the nature of the exclusively masculine plumage of many other birds.80 From the foregoing facts, more especially from neither sex of certain birds changing colour during either annual moult, or changing so slightly that the change can hardly be of any service to them, and from the females of other species moulting twice yet retaining the same colours throughout the year, we may conclude that the habit of annually moulting twice has not been acquired in order that the male should assume an orna* mental character during the breeding-season; but that the double moult, having been originally acquired for some distinct purpose, has subsequently been taken advantage of in certain cases for gaining a nuptial plumage. It appears at first sight a surprising circumstance that some closely-allied species should regularly undergo a double annual plumage of the ptarmigan is of as statements on moulting, see, on much importance to it, as a pro- snipes, &c, Macgillivray, * Hist, tection, as the white winter plu- Brit. Birds,' vol. iv. p. 371; on mage ; for in Scandinavia, during Glareolae, curlews, and bustards, the spring, when the snow has Jerdon, * Birds of India,' vol. iii. pp. disappeared, this bird is known to 615, 630, 683; on Totanus, ibid. p. suffer greatly from birds of prey, 700 ; on the plumes of herons, ibid, before it has acquired its summer p. 738, and Macgillivray, vol. iv. dress : see Wilhelra von Wright, in pp. 435 and 444, and Mr. Stafford Lloyd, * Game Birds of Sweden,' Allen , in the * Ibis,' vol. v. 1963, p. '867, p. 125. 33. *• Id regard to the previous 392 The JJe^cmt of Man. Paet IL moult, and others only a single one. The ptarmigan, for instance, moults twice or even thrice in the year, and the black- cock only once : some of the splendidly coloured honey-suckers (Nectarinise) of India and some sub-genera of obscurely coloured pipits (Anthus) have a double, whilst others have only a single annual moult.81 But the gradations in the manner of moulting, which are known to occur with various birds, shew us how species, or whole groups, might have originally acquired their double annual moult, or having once gained the habit, have again lost it. With certain bustards and plovers the vernal moult is far from complete, some feathers being renewed, and some changed in colour. There is also reason to believe that with certain bustards and rail-like birds, which properly under- go a double moult, some of the older males retain their nuptial plumage throughout the year. A few highly modified feathers may merely be added during the spring to the plumage, as occurs with the disc-formed tail-feathers of certain drongos (Bhringa) in India, and with the elongated feathers on the back, neck, and crest of certain herons. By such steps as these, the vernal moult might be rendered more and more complete, until a perfect double moult was acquired. Some of the birds of paradise retain their nuptial feathers throughout the year, and thus have only a single moult ; others cast them directly after the breeding-season, and thus have a double moult ; and others again cast them at this season during the first year, but not afterwards ; so that these latter species are intermediate in their manner of moulting. There is also a great difference with many birds in the length of time during which the two annual plumages are retained ; so that the one might come to be re- tained for the whole year, and the other completely lost. Thus in the spring Machetes pugnax retains his ruff for barely two months. In Natal the male widow-bird (Chera progne) acquires his fine plumage and long tail-feathers in December or January, and loses them in March; so that they are retained only for about three months. Most species, which undergo a double moult, keep their ornamental feathers for about six months The male, however, of the wild Gallus bankiva retains his neck- hackles for nine or ten months ; and when these are cast off, the underlying black feathers on the neck are fully exposed tc view. Bat with the domesticated descendant of this species, the neck- hackles of the male are immediately replaced by new ones • so •* On the moulting of the ptar- 359, 365, 369. On the moulting of migan, sae Gould's l Birds of Great Anthus, see Elytb, in 'Ibis,' 1867f Britain.' On the honey-suckers, p. 32. Jeir4o&, * Birds of Irdia,' vol, i. pp. Chap . XTII. Double A finnal Moult 393 that we here see, as to part of the plumage, a double moult changed under domestication into a single moult.82 The common drake (Anas boschas) after the breeding- season is well known to lose his male plumage for a period of three months, during which time he assumes that of the female. The male pintail-duck (Anas acuta) loses his plumage for the shorter period of six weeks or two months ; and Montagu remarks that " this double mourt within so short a time is a most extra- ' ordinary circumstance, that seems to bid defiance to all human " reasoning." But the believer in the gradual modification of species will be far from feeling surprise at finding gradations of all kinds. If the male pintail were to acquiro his new plumage within a still shorter period, the new male feathers would almost necessarily be mingled with the old, and both with some proper to the female ; and this apparently is the case with the male of a not distantly-allied bird, namely the Merganser serrator, for the males are said to " undergo a change of plumage, which " assimilates them in some measure to the female." By a little further acceleration in the process, the double moult would be completely lost.83 Some male birds, as before stated, become more brightly coloured in the spring, not by a vernal moult, but either by an actual change of colour in the feathers, or by their obscurely- coloured deciduary margins being shed. Changes of colour thus caused may last for a longer or shorter time. In the Pelecanus ohocrotalus a beautiful rosy tint, with lemon-coloured marks on the breast, overspreads the whole plumage in the spring ; but these tints, as Mr. Sclater states, " do not last long, disappearing " generally in about six weeks or two months after they have " been attained." Certain finches shed the margins of their feathers in the spring, and then become brighter coloured, while other finches undergo no such change. Thus the Fringilla tristis of the United States (as well as many other American species) 82 For the foregoing statements of the Herodias bubulcus, Mr. S. S. in regard to partial moults, and Allen, in *Ibis,' 1863, p. 33. Oa on old males retaining their nuptial Oallus bankiva, Blyth, in * Annals plumage, see Jerdou, on bustards and Mag. of Nat. Hist.' vol. i. 1848, and plovers, in ' Birds of India,' vol. p. 455 ; see, also, on this subject, iii. pp. 617, 637, 799, 711. Also my * Variation of Animals under Blyth in * Land and Wat**-,* 1867, Domestication,' vol. i. p. 236. p. 84. On the moulting of Para- 8S See Macgillivray, * Hist. British disea, see an interesting article by Birds ' (vol. v. pp. 34, 70, and 223), Dr. W. Marshall, ' Archives Neerlan- on the moulting of the Anatidas, daises,' torn. vi. 1871. On the Vidua, with quotations from Waterton and 'Ibis,' vol. iii. 1861, p. 133. On Montagu. Also Yarrell, 'Hist. of the Dron go-shrikes, Jerdon, ibid. British Birds,' vol. iii. p, 243t vpl, i. p. 435 Oo the vernal moult 394 The Descent of Man. Pabt II, exhibits its bright colours only when the winter is past, wliilst our goldfinch, which exactly represents this bird in habits, and our siskin, which represents it still more closely in structure, undergo no such annual change. But a difference of this kind in the plumage of allied species is not surprising, for with the common linnet, which belongs to the same family, the crimson forehead and breast are displayed only during the summer in England, whilst in Madeira these colours are retained through- out the year.84 Display by Male Birds of their Plumage. — Ornaments of all kinds, whether permanently or temporarily gained, are sedulously displayed by the males, and apparently serve to excite, attract, or fascinate the females. But the males will sometimes display their ornaments, when not in the presence of the females, as occasionally occurs with grouse at their balz-places, and as may be noticed with the peacock; this latter bird, however, evidently wishes for a spectator of some kind, and, as I have often seen, will shew off his finery before poultry, or even pigs.86 All natu- ralists who have closely attended to the habits of birds, whether in a state of nature or under confinement, are unanimously of opinion that the males take delight in displaying their beauty. Audubon frequently speaks of the male as endeavouring in various ways to charm the female. Mr. Gould, after describing some peculiarities in a male humming-bird, says he has no doubt that it has the power of displaying them to the greatest advantage before the female. Dr. Jerdon 86 insists that the beautiful plum- age of the male serves " to fascinate and attract the female." Mr. Bartlett, at the Zoological Gardens, expressed himself to me in the strongest terms to the same effect. It must be a grand sight in the forests of India " to come " suddenly on twenty or thirty pea -fowl, the males displaying ■ " their gorgeous trains, and strutting about in all the pomp ot ' pride before the gratified females." The wild turkey-cock erects his glittering plumage, expands his finely-zoned tail and barred wing-feathers, and altogether, with his crimson and blue wattles, makes a superb, though to our eyes, grotesque 84 On the pelican, see Sclater, in 1863, p. 230. 'Proc. Zool. Soc.' 1868, p. 265. 85 See also « Ornamental Poultry,' On the American finches, see Au- by Rev. E. S. Dixon, 1848, p. 8. dabon, * Ornith. Biography/ vol. i. 8