{"collection":"aor","html_url":"https://unchartedknowledge.5gfusion.net/browse/aor/darwin/descent/dm02.htm","path":"aor/darwin/descent/dm02.htm","source_url":"https://sacred-texts.com/aor/darwin/descent/dm02.htm","text":"Chapter II - On the Manner of Development of Man from some Lower Form\n IT is manifest that man is now subject to much variability. No two\nindividuals of the same race are quite alike. We may compare\nmillions of faces, and each will be distinct. There is an equally\ngreat amount of diversity in the proportions and dimensions of the\nvarious parts of the body; the length of the legs being one of the\nmost variable points.* Although in some quarters of the world an\nelongated skull, and in other quarters a short skull prevails, yet\nthere is great diversity of shape even within the limits of the same\nrace, as with the aborigines of America and South Australia- the\nlatter a race \"probably as pure and homogeneous in blood, customs, and\nlanguage as any in existence\"- and even with the inhabitants of so\nconfined an area as the Sandwich Islands.*(2) An eminent dentist\nassures me that there is nearly as much diversity in the teeth as in\nthe features. The chief arteries so frequently run in abnormal\ncourses, that is has been found useful for surgical purposes to\ncalculate from 1040 corpses how often each course prevails.*(3) The\nmuscles are eminently variable: thus those of the foot were found by\nProf. Turner*(4) not to be strictly alike in any two out of fifty\nbodies; and in some the deviations were considerable. He adds, that\nthe power of performing the appropriate movements must have been\nmodified in accordance with the several deviations. Mr. J. Wood has\nrecorded*(5) the occurrence of 295 muscular variations in thirty-six\nsubjects, and in another set of the same number no less than 558\nvariations, those occurring on both sides of the body being only\nreckoned as one. In the last set, not one body out of the thirty-six\nwas \"found totally wanting in departures from the standard\ndescriptions of the muscular system given in anatomical text books.\" A\nsingle body presented the extraordinary number of twenty-five distinct\nabnormalities. The same muscle sometimes varies in many ways: thus\nProf. Macalister describes*(6) no less than twenty distinct variations\nin the palmaris accessorius.\n * Investigations in the Military and Anthropological Statistics of\nAmerican Soldiers, by B. A. Gould, 1869, p. 256.\n *(2) With respect to the \" Cranial forms of the American\naborigines,\" see Dr. Aitken Meigs in Proc. Acad. Nat. Sci.\nPhiladelphia, May, 1868. On the Australians, see Huxley, in Lyell's\nAntiquity of Man, 1863, p. 87. On the Sandwich Islanders, Prof. J.\nWyman, Observations on Crania, Boston, 1868, p. 18.\n *(3) Anatomy of the Arteries, by R. Quain. Preface, vol. i., 1844.\n *(4) Transactions of the Royal Society of Edinburgh, vol. xxiv., pp.\n175, 189.\n *(5) Proceedings Royal Society, 1867, p. 544; also 1868, pp. 483,\n524. There is a previous paper, 1866, p. 229.\n *(6) Proc. R. Irish Academy, vol. x., 1868, p. 141.\n The famous old anatomist, Wolff,* insists that the internal\nviscera are more variable than the external parts: Nulla particula est\nquae non aliter et aliter in aliis se habeat hominibus. He has even\nwritten a treatise on the choice of typical examples of the viscera\nfor representation. A discussion on the beau-ideal of the liver,\nlungs, kidneys, &c., as of the human face divine, sounds strange in\nour ears.\n * Act. Acad. St. Petersburg, 1778, part ii., p. 217.\n The variability or diversity of the mental faculties in men of the\nsame race, not to mention the greater differences between the men of\ndistinct races, is so notorious that not a word need here be said.\nSo it is with the lower animals. All who have had charge of menageries\nadmit this fact, and we see it plainly in our dogs and other\ndomestic animals. Brehm especially insists that each individual monkey\nof those which he kept tame in Africa had its own peculiar disposition\nand temper: he mentions one baboon remarkable for its high\nintelligence; and the keepers in the Zoological Gardens pointed out to\nme a monkey, belonging to the New World division, equally remarkable\nfor intelligence. Rengger, also, insists on the diversity in the\nvarious mental characters of the monkeys of the same species which\nhe kept in Paraguay; and this diversity, as he adds, is partly innate,\nand partly the result of the manner in which they have been treated or\neducated.*\n * Brehm, Illustriertes Thierleben, B. i., ss. 58, 87. Rengger,\nSaugethiere von Paraguay, s. 57.\n I have elsewhere* so fully discussed the subject of Inheritance,\nthat I need here add hardly anything. A greater number of facts have\nbeen collected with respect to the transmission of the most\ntrifling, as well as of the most important characters in man, than\nin any of the lower animals; though the facts are copious enough\nwith respect to the latter. So in regard to mental qualities, their\ntransmission is manifest in our dogs, horses, and other domestic\nanimals. Besides special tastes and habits, general intelligence,\ncourage, bad and good temper, &c., are certainly transmitted. With man\nwe see similar facts in almost every family; and we now know,\nthrough the admirable labours of Mr. Galton,*(2) that genius which\nimplies a wonderfully complex combination of high faculties, tends\nto be inherited; and, on the other hand, it is too certain that\ninsanity and deteriorated mental powers likewise run in families.\n * Variation of Animals and Plants under Domestication, vol. ii.,\nchap. xii.\n *(2) Hereditary Genius: an Inquiry into its Laws and Consequences,\n1869.\n With respect to the causes of variability, we are in all cases\nvery ignorant; but we can see that in man as in the lower animals,\nthey stand in some relation to the conditions to which each species\nhas been exposed, during several generations. Domesticated animals\nvary more than those in a state of nature; and this is apparently\ndue to the diversified and changing nature of the conditions to\nwhich they have been subjected. In this respect the different races of\nman resemble domesticated animals, and so do the individuals of the\nsame race, when inhabiting. a very wide area, like that of America. We\nsee the influence of diversified conditions in the more civilised\nnations; for the members belonging to different grades of rank, and\nfollowing different occupations, present a greater range of\ncharacter than do the members of barbarous nations. But the uniformity\nof savages has often been exaggerated, and in some cases can hardly be\nsaid to exist.* It is, nevertheless, an error to speak of man, even if\nwe look only to the conditions to which he has been exposed, as \"far\nmore domesticated\"*(2) than any other animal. Some savage races,\nsuch as the Australians, are not exposed to more diversified\nconditions than are many species which have a wide range. In another\nand much more important respect, man differs widely from any\nstrictly domesticated animal; for his breeding has never long been\ncontrolled, either by methodical or unconscious selection. No race\nor body of men has been so completely subjugated by other men, as that\ncertain individuals should be preserved, and thus unconsciously\nselected, from somehow excelling in utility to their masters. Nor have\ncertain male and female individuals been intentionally picked out\nand matched, except in the well-known case of the Prussian grenadiers;\nand in this case man obeyed, as might have been expected, the law of\nmethodical selection; for it is asserted that many tall men were\nreared in the villages inhabited by the grenadiers and their tall\nwives. In Sparta, also, a form of selection was followed, for it was\nenacted that all children should be examined shortly after birth;\nthe well-formed and vigorous being preserved, the others left to\nperish.*(3)\n * Mr. Bates remarks (The Naturalist on the Amazons, 1863, vol. ii p.\n159), with respect to the Indians of the same South American tribe,\n\"no two of them were at all similar in the shape of the head; one\nman had an oval visage with fine features, and another was quite\nMongolian in breadth and prominence of cheek, spread of nostrils,\nand obliquity of eyes.\"\n *(2) Blumenbach, Treatises on Anthropology., Eng. translat., 1865,\np. 205.\n *(3) Mitford's History of Greece, vol. i., p. 282. It appears from a\npassage in Xenophon's Memorabilia, B. ii. 4 (to which my attention has\nbeen called by the Rev. J. N. Hoare), that it was a well recognised\nprinciple with the Greeks, that men ought to select their wives with a\nview to the health and vigour of their children. The Grecian poet,\nTheognis, who lived 550 B. C., clearly saw how important selection, if\ncarefully applied, would be for the improvement of mankind. He saw,\nlikewise, that wealth often checks the proper action of sexual\nselection. He thus writes:\n With kine and horses, Kurnus! we proceed\n By reasonable rules, and choose a breed\n For profit and increase at any price:\n Of a sound stock, without defect or vice.\n But, in the daily matches that we make,\n The price is everything: for money's sake,\n Men marry: women are in marriage given\n The churl or ruffian, that in wealth has thriven,\n May match his offspring with the proudest race:\n Thus everything is mix'd, noble and base!\n If then in outward manner, form, and mind,\n You find us a degraded, motley kind,\n Wonder no more, my friend! the cause is plain,\n And to lament the consequence is vain.\n (The Works of J. Hookham Frere, vol. ii., 1872, p. 334.)\n If we consider all the races of man as forming a single species, his\nrange is enormous; but some separate races, as the Americans and\nPolynesians, have very wide ranges. It is a well-known law that\nwidely-ranging species are much more variable than species with\nrestricted ranges; and the variability of man may with more truth be\ncompared with that of widely-ranging species, than with that of\ndomesticated animals.\n Not only does variability appear to be induced in man and the\nlower animals by the same general causes, but in both the same parts\nof the body are effected in a closely analogous manner. This has\nbeen proved in such full detail by Godron and Quatrefages, that I need\nhere only refer to their works.* Monstrosities, which graduate into\nslight variations, are likewise so similar in man and the lower\nanimals, that the same classification and the same terms can be used\nfor both, as has been shewn by Isidore Geoffroy St-Hilaire.*(2) In\nmy work on the variation of domestic animals, I have attempted to\narrange in a rude fashion the laws of variation under the following\nheads:- The direct and definite action of changed conditions, as\nexhibited by all or nearly all the individuals of the same species,\nvarying in the same manner under the same circumstances. The effects\nof the long-continued use or disuse of parts. The cohesion of\nhomologous parts. The variability of multiple parts. Compensation of\ngrowth; but of this law I have found no good instance in the case of\nman. The effects of the mechanical pressure of one part on another; as\nof the pelvis on the cranium of the infant in the womb. Arrests of\ndevelopment, leading to the diminution or suppression of parts. The\nreappearance of long-lost characters through reversion. And lastly,\ncorrelated variation. All these so-called laws apply equally to man\nand the lower animals; and most of them even to plants. It would be\nsuperfluous here to discuss all of them;*(3) but several are so\nimportant, that they must be treated at considerable length.\n * Godron, De l'Espece, 1859, tom. ii., livre 3. Quatrefages, Unite\nde l'Espece Humaine, 1861. Also Lectures on Anthropology, given in the\nRevue des Cours Scientifiques, 1866-1868.\n *(2) Hist. Gen. et Part. des Anomalies de l'Organisation, tom. i.,\n1832.\n *(3) I have fully discussed these laws in my Variation of Animals\nand Plants under Domestication, vol. ii., chaps. xxii. and xxiii. M.\nJ. P. Durand has lately (1868) published a valuable essay, De\nl'Influence des Milieux, &c. He lays much stress, in the case of\nplants, on the nature of the soil.\n The Direct and Definite Action of Changed Conditions.- This is a\nmost perplexing subject. It cannot be denied that changed conditions\nproduce some, and occasionally a considerable effect, on organisms\nof all kinds; and it seems at first probable that if sufficient time\nwere allowed this would be the invariable result. But I have failed to\nobtain clear evidence in favour of this conclusion; and valid\nreasons may be urged on the other side, at least as far as the\ninnumerable structures are concerned, which are adapted for special\nends. There can, however, be no doubt that changed conditions induce\nan almost indefinite amount of fluctuating variability, by which the\nwhole organisation is rendered in some degree plastic.\n In the United States, above 1,000,000 soldiers, who served in the\nlate war, were measured, and the States in which they were born and\nreared were recorded.* From this astonishing number of observations it\nis proved that local influences of some kind act directly on\nstature; and we further learn that \"the State where the physical\ngrowth has in great measure taken place, and the State of birth, which\nindicates the ancestry, seem to exert a marked influence on the\nstature.\" For instance, it is established, \"that residence in the\nWestern States, during the years of growth, tends to produce\nincrease of stature.\" On the other hand, it is certain that with\nsailors, their life delays growth, as shewn \"by the great difference\nbetween the statures of soldiers and sailors at the ages of\nseventeen and eighteen years.\" Mr. B. A. Gould endeavoured to\nascertain the nature of the influences which thus act on stature;\nbut he arrived only at negative results, namely that they did not\nrelate to climate, the elevation of the land, soil, nor even \"in any\ncontrolling degree\" to the abundance or the need of the comforts of\nlife. This latter conclusion is directly opposed to that arrived at\nby, Villerme, from the statisties of the height of the conscripts in\ndifferent parts of France. When we compare the differences in\nstature between the Polynesian chiefs and the lower orders within\nthe same islands, or between the inhabitants of the fertile volcanic\nand low barren coral islands of the same ocean,*(2) or again between\nthe Fuegians on the eastern and western shores of their country, where\nthe means of subsistence are very different, it is scarcely possible\nto avoid the conclusion that better food and greater comfort do\ninfluence stature. But the preceding statements shew how difficult\nit is to arrive at any precise result. Dr. Beddoe has lately proved\nthat, with the inhabitants of Britain, residence in towns and\ncertain occupations have a deteriorating influence on height; and he\ninfers that the result is to a certain extent inherited, as is\nlikewise the case in the United States. Dr. Beddoe further believes\nthat wherever a \"race attains its maximum of physical development,\nit rises highest in energy and moral vigour.\"*(3)\n * Investigations in Military and Anthrop. Statistics, &c., 1869,\nby B. A. Gould, pp. 93, 107, 126, 131, 134.\n *(2) For the Polynesians, see Prichard's Physical History of\nMankind, vol. v., 1847, pp. 145, 283. Also Godron, De l'Espece, tom.\nii., p. 289. There is also a remarkable difference in appearance\nbetween the closely-allied Hindoos inhabiting the Upper Ganges and\nBengal; see Elphinstone's History of India, vol. i., p. 324.\n *(3) Memoirs, Anthropological Society, vol. iii., 1867-69, pp.\n561, 565, 567.\n Whether external conditions produce any other direct effect on man is\nnot known. It might have been expected that differences of climate\nwould have had a marked influence, inasmuch as the lungs and kidneys\nare brought into activity under a low temperature, and the liver and\nskin under a high one.* It was formerly thought that the colour of the\nskin and the character of the hair were determined by light or heat;\nand although it can hardly be denied that some effect is thus\nproduced, almost all observers now agree that the effect has been very\nsmall, even after exposure during many ages. But this subject will\nbe more properly discussed when we treat of the different races of\nmankind. With our domestic animals there are grounds for believing\nthat cold and damp directly affect the growth of the hair; but I\nhave not met with any evidence on this head in the case of man.\n * Dr. Brakenridge, \"Theory of Diathesis,\" Medical Times, June 19 and\nJuly 17, 1869.\n Effects of the increased Use and Disuse of Parts.- It is well\nknown that use strengthens the muscles in the individual, and complete\ndisuse, or the destruction of the proper nerve, weakens them. When the\neye is destroyed, the optic nerve often becomes atrophied. When an\nartery is tied, the lateral channels increase not only in diameter,\nbut in the thickness and strength of their coats. When one kidney\nceases to act from disease, the other increases in size, and does\ndouble work. Bones increase not only in thickness, but in length, from\ncarrying a greater weight.* Different occupations, habitually\nfollowed, lead to changed proportions in various parts of the body.\nThus it was ascertained by the United States Commission*(2) that the\nlegs of the sailors employed in the late war were longer by 0.217 of\nan inch than those of the soldiers, though the sailors were on an\naverage shorter men; whilst their arms were shorter by 1.09 of an\ninch, and therefore, out of proportion, shorter in relation to their\nlesser height. This shortness of the arms is apparently due to their\ngreater use, and is an unexpected result: but sailors chiefly use\ntheir arms in pulling, and not in supporting weights. With sailors,\nthe girth of the neck and the depth of the instep are greater,\nwhilst the circumference of the chest, waist, and hips is less, than\nin soldiers.\n * I have given authorities for these several statements in my\nVariation of Animals and Plants under Domestication, vol. ii., pp.\n297-300. Dr. Jaeger, \"Uber das Langenwachsthum der Knochen,\" Jenaische\nZeitschrift, B. v., Heft. i.\n *(2) Investigations, &c., by B. A. Gould, 1869, p. 288.\n Whether the several foregoing modifications would become hereditary,\nif the same habits of life were followed during many generations, is\nnot known, but it is probable. Rengger* attributes the thin legs and\nthick arms of the Payaguas Indians to successive generations having\npassed nearly their whole lives in canoes, with their lower\nextremities motionless. Other writers have come to a similar\nconclusion in analogous cases. According to Cranz,*(2) who lived for a\nlong time with the Esquimaux, \"The natives believe that ingenuity\nand dexterity in seal-catching (their highest art and virtue) is\nhereditary; there is is really something in it, for the son of a\ncelebrated seal-catcher will distinguish himself, though he lost his\nfather in childhood.\" But in this case it is mental aptitude, quite as\nmuch as bodily structure, which appears to be inherited. It is\nasserted that the hands of English labourers are at birth larger\nthan those of the gentry.*(3) From the correlation which exists, at\nleast in some cases,*(4) between the development of the extremities\nand of the jaws, it is possible that in those classes which do not\nlabour much with their hands and feet, the jaws would be reduced in\nsize from this cause. That they are generally smaller in refined and\ncivilized men than in hard-working men or savages, is certain. But\nwith savages, as Mr. Herbert Spencer*(5) has remarked, the greater use\nof the jaws in chewing coarse, uncooked food, would act in a direct\nmanner on the masticatory muscles, and on the bones to which they\nare attached. In infants, long before birth, the skin on the soles\nof the feet is thicker than on any other part of the body;*(6) and\nit can hardly be doubted that this is due to the inherited effects\nof pressure during a long series of generations.\n * Saugethiere von Paraguay, 1830, s. 4.\n *(2) History of Greenland, Eng. translat., 1767, vol. i., p. 230\n *(3) Intermarriage, by Alex. Walker, 1838, p. 377.\n *(4) The Variation of Animals and Plants under Domestication, vol.\ni., p. 173.\n *(5) Principles of Biology, vol. i., p. 455.\n *(6) Paget, Lectures on Surgical Pathology, vol. ii, 1853, p. 209.\n It is familiar to every one that watchmakers and engravers are\nliable to be short-sighted, whilst men living much out of doors, and\nespecially savages, are generally long-sighted.* Short-sight and\nlong-sight certainly tend to be inherited.*(2) The inferiority of\nEuropeans, in comparison with savages, in eyesight and in the other\nsenses, is no doubt the accumulated and transmitted effect of lessened\nuse during many generations; for Rengger*(3) states that he has\nrepeatedly observed Europeans, who had been brought up and spent their\nwhole lives with the wild Indians, who nevertheless did not equal them\nin the sharpness of their senses. The same naturalist observes that\nthe cavities in the skull for the reception of the several\nsense-organs are larger in the American aborigines than in\nEuropeans; and this probably indicates a corresponding difference in\nthe dimensions of the organs themselves. Blumenbach has also\nremarked on the large size of the nasal cavities in the skulls of\nthe American aborigines, and connects this fact with their\nremarkably acute power of smell. The Mongolians of the plains of\nnorthern Asia, according to Pallas, have wonderfully perfect senses;\nand Prichard believes that the great breadth of their skulls across\nthe zygomas follows from their highly-developed sense organs.*(4)\n * It is a singular and unexpected fact that sailors are inferior\nto landsmen in their mean distance of distinct vision. Dr. B. A. Gould\n(Sanitary Memoirs of the War of the Rebellion, 1869 p. 530), has\nproved this to be the case; and he accounts for it by the ordinary\nrange of vision in sailors being \"restricted to the length of the\nvessel and the height of the masts.\"\n *(2) The Variation of Animal and Plants under Domestication, vol.\ni., p. 8.\n *(3) Saugethiere von Paraguay, s. 8, 10. I have had good\nopportunities for observing the extraordinary power of eyesight in the\nFuegians. See also Lawrence (Lectures on Physiology, &c., 1822, p.\n404) on this same subject. M. Giraud-Teulon has recently collected\n(Revue des Cours Scientifiques, 1870, p. 625) a large and valuable\nbody of evidence proving that the cause of short-sight, \"C'est le\ntravail assidu, de pres.\"\n *(4) Prichard, Physical History of Mankind, on the authority of\nBlumenbach, vol. i., 1841, p. 311; for the statement by Pallas, vol.\niv., 1844, p. 407.\n The Quechua Indians inhabit the lofty plateaux of Peru; and Alcide\nd'Orbigny states* that, from continually breathing a highly rarefied\natmosphere, they have acquired chests and lungs of extraordinary\ndimensions. The cells, also, of the lungs are larger and more numerous\nthan in Europeans. These observations have been doubted, but Mr. D.\nForbes carefully measured many Aymaras, an allied race, living at\nthe height of between 10,000 and 15,000 feet; and he informs me*(2)\nthat they differ conspicuously from the men of all other races seen by\nhim in the circumference and length of their bodies. In his table of\nmeasurements, the stature of each man is taken at 1000, and the\nother measurements are reduced to this standard. It is here seen\nthat the extended arms of the Aymaras are shorter than those of\nEuropeans, and much shorter than those of Negroes. The legs are\nlikewise shorter; and they present this remarkable peculiarity, that\nin every Aymara measured, the femur is actually shorter than the\ntibia. On an average, the length of the femur to that of the tibia\nis as 211 to 252; whilst in two Europeans, measured at the same\ntime, the femora to the tibiae were as 244 to 230; and in three\nNegroes as 258 to 241. The humerus is likewise shorter relatively to\nthe forearm. This shortening of that part of the limb which is nearest\nto the body, appears to be, as suggested to me by Mr. Forbes, a case\nof compensation in relation with the greatly increased length of the\ntrunk. The Aymaras present some other singular points of structure,\nfor instance, the very small projection of the heel.\n * Quoted by Prichard, Researches into the Physical History of\nMankind, vol. v., p. 463.\n *(2) Mr. Forbes' valuable paper is now published in the Journal of\nthe Ethnological Society of London, new series, vol. ii., 1870, p.\n193.\n These men are so thoroughly acclimatised to their cold and lofty\nabode, that when formerly carried down by Spaniards to the low eastern\nplains, and when now tempted down by high wages to the\ngold-washings, they suffer a frightful rate of mortality. Nevertheless\nMr. Forbes found a few pure families which had survived during two\ngenerations: and he observed that they still inherited their\ncharacteristic peculiarities. But it was manifest, even without\nmeasurement, that these peculiarities had all decreased; and on\nmeasurement, their bodies were found not to be so much elongated as\nthose of the men on the high plateau; whilst their femora had become\nsomewhat lengthened, as had their tibiae, although in a less degree.\nThe actual measurements may be seen by consulting Mr. Forbes's memoir.\nFrom these observations, there can, I think, be no doubt that\nresidence during many generations at a great elevation tends, both\ndirectly and indirectly, to induce inherited modifications in the\nproportions of the body.*\n * Dr. Wilckens (Landwirthschaft. Wochenblatt, No. 10, 1869) has\nlately published an interesting essay shewing how domestic animals,\nwhich live in mountainous regions, have their frames modified.\n Although man may not have been much modified during the latter\nstages of his existence through the increased or decreased use of\nparts, the facts now given shew that his liability in this respect has\nnot been lost; and we positively know that the same law holds good\nwith the lower animals. Consequently we may infer that when at a\nremote epoch the progenitors of man were in a transitional state,\nand were changing from quadrupeds into bipeds, natural selection would\nprobably have been greatly aided by the inherited effects of the\nincreased or diminished use of the different parts of the body.\n Arrests of Development.- There is a difference between arrested\ndevelopment and arrested growth, for parts in the former state\ncontinue to grow whilst still retaining their early condition. Various\nmonstrosities come under this head; and some, as a cleft palate, are\nknown to be occasionally inherited. It will suffice for our purpose to\nrefer to the arrested brain-development of microcephalous idiots, as\ndescribed in Vogt's memoir.* Their skulls are smaller, and the\nconvolutions of the brain are less complex than in normal men. The\nfrontal sinus, or the projection over the eyebrows, is largely\ndeveloped, and the jaws are prognathous to an \"effrayant\" degree; so\nthat these idiots somewhat resemble the lower types of mankind.\nTheir intelligence, and most of their mental faculties, are\nextremely feeble. They cannot acquire the power of speech, and are\nwholly incapable of prolonged attention, but are much given to\nimitation. They are strong and remarkably active, continually\ngambolling and jumping about, and making grimaces. They often ascend\nstairs on all-fours; and are curiously fond of climbing up furniture\nor trees. We are thus reminded of the delight shewn by almost all boys\nin climbing trees; and this again reminds us how lambs and kids,\noriginally alpine animals, delight to frisk on any hillock, however\nsmall. Idiots also resemble the lower animals in some other\nrespects; thus several cases are recorded of their carefully\nsmelling every mouthful of food before eating it. One idiot is\ndescribed as often using his mouth in aid of his hands, whilst hunting\nfor lice. They are often filthy in their habits, and have no sense\nof decency; and several cases have been published of their bodies\nbeing remarkably hairy.*(2)\n * Memoires sur les Microcephales, 1867, pp. 50, 125, 169, 171,\n184-198.\n *(2) Prof. Laycock sums up the character of brute-like idiots by\ncalling them theroid; Journal of Mental Science,, July, 1863. Dr.\nScott (The Deaf and Dumb, 2nd ed., 1870, p. 10) has often observed the\nimbeciles smelling their food. See, on this same subject, and on the\nhairiness of idiots, Dr. Maudsley, Body and Mind, 1870, pp. 46-51.\nPinel has also given a striking case of hairiness in an idiot.\n Reversion.- Many of the cases to be here given, might have been\nintroduced under the last heading. When a structure is arrested in its\ndevelopment, but still continues growing, until it closely resembles a\ncorresponding structure in some lower and adult member of the same\ngroup, it may in one sense be considered as a case of reversion. The\nlower members in a group give us some idea how the common progenitor\nwas probably constructed; and it is hardly credible that a complex\npart, arrested at an early phase of embryonic development, should go\non growing so as ultimately to perform its proper function, unless\nit had acquired such power during some earlier state of existence,\nwhen the present exceptional or arrested structure was normal. The\nsimple brain of a microcephalous idiot, in as far as it resembles that\nof an ape' may in this sense be said to offer a case of reversion.*\nThere are other cases which come more strictly under our present\nhead of reversion. Certain structures, regularly occurring in the\nlower members of the group to which man belongs, occasionally make\ntheir appearance in him, though not found in the normal human\nembryo; or, if normally present in the human embryo, they become\nabnormally developed, although in a manner which is normal in the\nlower members of the group. These remarks will be rendered clearer\nby the following illustrations.\n * In my Variation of Animals under Domestication (vol. ii., p.\n57), I attributed the not very rare cases of supernumerary mammae in\nwomen to reversion. I was led to this as a probable conclusion, by the\nadditional mammae being generally placed symmetrically on the\nbreast; and more especially from one case, in which a single efficient\nmamma occurred in the inguinal region of a woman, the daughter of\nanother woman with supernumerary mammae. But I now find (see, for\ninstance, Prof. Preyer, Der Kampf um das Dasein, 1869, s. 45) that\nmammae erraticae, occur in other situations, as on the back, in the\narmpit, and on the thigh; the mammae in this latter instance having\ngiven so much milk that the child was thus nourished. The\nprobability that the additional mammae are due to reversion is thus\nmuch weakened; nevertheless, it still seems to me probable, because\ntwo pairs are often found symmetrically on the breast; and of this I\nmyself have received information in several cases. It is well known\nthat some lemurs normally have two pairs of mammae on the breast. Five\ncases have been recorded of the presence of more than a pair of mammee\n(of course rudimentary) in the male sex of mankind; see Journal of\nAnat. and Physiology, 1872, p. 56, for a case given by Dr. Handyside\nin which two brothers exhibited this peculiarity; see also a paper\nby Dr. Bartels, in Reichert's and du Bois-Reymond's Archiv., 1872,\np. 304. In one of the cases alluded to by Dr. Bartels, a man bore five\nmammae, one being medial and placed above the navel; Meckel von\nHemsbach thinks that this latter case is illustrated by a medial mamma\noccurring in certain Cheiroptera. On the whole, we may well doubt if\nadditional mammae would ever have been developed in both sexes of\nmankind, had not his early progenitors been provided with more than\na single pair.\n In the above work (vol. ii., p. 12), I also attributed, though\nwith much hesitation, the frequent cases of polydactylism in men and\nvarious animals to reversion. I was partly led to this through Prof.\nOwen's statement, that some of the Ichthyopterygia possesses more than\nfive digits, and therefore, as I supposed, had retained a primordial\ncondition; but Prof. Gegenbaur (Jenaische Zeitschrift, B. v., Heft\n3, s. 341), disputes Owen's conclusion. On the other hand, according\nto the opinion lately advanced by Dr. Gunther, on the paddle of\nCeratodus, which is provided with articulated bony rays on both\nsides of a central chain of bones, there seems no great difficulty\nin admitting that six or more digits on one side, or on both sides,\nmight reappear through reversion. I am informed by Dr. Zouteveen\nthat there is a case on record of a man having twenty-four fingers and\ntwenty-four toes! I was chiefly led to the conclusion that the\npresence of supernumerary digits might be due to reversion from the\nfact that such digits, not only are strongly inherited, but, as I then\nbelieved, had the power of regrowth after amputation, like the\nnormal digits of the lower Vertebrata. But I have explained in the\nsecond edition of my Variation under Domestication why I now place\nlittle reliance on the recorded cases of such regrowth. Nevertheless\nit deserves notice, inasmuch as arrested development and reversion are\nintimately related processes; that various structures in an\nembryonic or arrested condition, such as a cleft palate, bifid uterus,\n&c., are frequently accompanied by polydactylism. This has been\nstrongly insisted on by Meckel and Isidore Geoffroy St-Hilaire. But at\npresent it is the safest course to give up altogether the idea that\nthere is any relation between the development of supernumerary\ndigits and reversion to some lowly organized progenitor of man.\n In various mammals the uterus graduates from a double organ with two\ndistinct orifices and two passages, as in the marsupials, into a\nsingle organ, which is in no way double except from having a slight\ninternal fold, as in the higher apes and man. The rodents exhibit a\nperfect series of gradations between these two extreme states. In\nall mammals the uterus is developed from two simple primitive tubes,\nthe inferior portions of which form the cornua; and it is in the words\nof Dr. Farre, \"by the coalescence of the two cornua at their lower\nextremities that the body of the uterus is formed in man; while in\nthose animals in which no middle portion or body exists, the cornua\nremain ununited. As the development of the uterus proceeds, the two\ncornua become gradually shorter, until at length they are lost, or, as\nit were, absorbed into the body of the uterus.\" The angles of the\nuterus are still produced into cornua, even in animals as high up in\nthe scale as the lower apes and lemurs.\n Now in women, anomalous cases are not very infrequent, in which\nthe mature uterus is furnished with cornua, or is partially divided\ninto two organs; and such cases, according to Owen, repeat \"the\ngrade of concentrative development,\" attained by certain rodents. Here\nperhaps we have an instance of a simple arrest of embryonic\ndevelopment, with subsequent growth and perfect functional\ndevelopment; for either side of the partially double uterus is capable\nof performing the proper office of gestation. In other and rarer\ncases, two distinct uterine cavities are formed, each having its\nproper orifice and passage.* No such stage is passed through during\nthe ordinary development of the embryo; and it is difficult to\nbelieve, though perhaps not impossible, that the two simple, minute,\nprimitive tubes should know how (if such an expression may be used) to\ngrow into two distinct uteri, each with a well-constructed orifice,and\npassage, and each furnished with numerous muscles, nerves, glands\nand vessels, if they had not formerly passed through a similar\ncourse of development, as in the case of existing marsupials. No one\nwill pretend that so perfect a structure as the abnormal double uterus\nin woman could be the result of mere chance. But the principle of\nreversion, by which a long-lost structure is called back into\nexistence, might serve as the guide for its full development, even\nafter the lapse of an enormous interval of time.\n * See Dr. A. Farre's well-known article in the Cyclopaedia of\nAnatomy and Physiology, vol. v., 1859, p. 642. Owen, Anatomy of\nVertebrates, vol. iii., 1868, p. 687. Professor Turner, in Edinburgh\nMedical Journal, February, 1865.\n Professor Canestrini, after discussing the foregoing and various\nanalogous cases, arrives at the same conclusion as that just given. He\nadduces another instance, in the case of the malar bone,* which, in\nsome of the Quadrumana and other mammals, normally consists of two\nportions. This is its condition in the human foetus when two months\nold; and through arrested development, it sometimes remains thus in\nman when adult, more especially in the lower prognathous races.\nHence Canestrini concludes that some ancient progenitor of man must\nhave had this bone normally divided into two portions, which\nafterwards became fused together. In man the frontal bone consists\nof a single piece, but in the embryo, and in children, and in almost\nall the lower mammals, it consists of two pieces separated by a\ndistinct suture. This suture occasionally persists more or less\ndistinctly in man after maturity; and more frequently in ancient\nthan in recent crania, especially, as Canestrini has observed, in\nthose exhumed from the Drift, and belonging to the brachycephalic\ntype. Here again he comes to the same conclusion as in the analogous\ncase of the malar bones. In this, and other instances presently to\nbe given, the cause of ancient races approaching the lower animals\nin certain characters more frequently than do the modern races,\nappears to be, that the latter stand at a somewhat greater distance in\nthe long line of descent from their early semi-human progenitors.\n * Annuario della Soc. dei Naturalisti, Modena, 1867, p. 83. Prof.\nCanestrini gives extracts on this subject from various authorities.\nLaurillard remarks, that as he has found a complete similarity in\nthe form, proportions, and connection of the two malar bones in\nseveral human subjects and in certain apes, he cannot consider this\ndisposition of the parts as simply accidental. Another paper on this\nsame anomaly has been published by Dr. Saviotti in the Gazzetta\ndelle Cliniche, Turin, 1871, where he says that traces of the division\nmay be detected in about two per cent of adult skulls; he also remarks\nthat it more frequently occurs in prognathous skulls, not of the Aryan\nrace, than in others. See also G. Delorenzi on the same subject;\n\"Tre nuovi casi d'anomalia dell' osso malare,\" Torino, 1872. Also,\nE. Morselli, \"Sopra una rara anomalia dell' osso malare,\" Modena,\n1872. Still more recently Gruber has written a pamphlet on the\ndivision of this bone. I give these references because a reviewer,\nwithout any grounds or scruples, has thrown doubts on my statements.\n Various other anomalies in man, more or less analogous to the\nforegoing, have been advanced by different authors, as cases of\nreversion; but these seem not a little doubtful, for we have to\ndescend extremely low in the mammalian series, before we find such\nstructures normally present.*\n * A whole series of cases is given by Isidore Geoffroy St-Hilaire,\nHist. des Anomalies, tom, iii, p. 437. A reviewer (Journal of\nAnatomy and Physiology, 1871, p. 366) blames me much for not having\ndiscussed the numerous cases, which have been recorded, of various\nparts arrested in their development. He says that, according to my\ntheory, \"every transient condition of an organ, during its\ndevelopment, is not only a means to an end, but once was an end in\nitself.\" This does not seem to me necessarily to hold good. Why should\nnot variations occur during an early period of development, having\nno relation to reversion; yet such variations might be preserved and\naccumulated, if in any way serviceable, for instance, in shortening\nand simplifying the course of development? And again, why should not\ninjurious abnormalities, such as atrophied or hypertrophied parts,\nwhich have no relation to a former state of existence, occur at an\nearly period, as well as during maturity?\n In man, the canine teeth are perfectly efficient instruments for\nmastication. But their true canine character, as Owen* remarks, \"is\nindicated by the conical form of the crown, which terminates in an\nobtuse point, is convex outward and flat or sub-concave within, at the\nbase of which surface there is a feeble prominence. The conical form\nis best expressed in the Melanian races, especially the Australian.\nThe canine is more deeply implanted, and by a stronger fang than the\nincisors.\" Nevertheless, this tooth no longer serves man as a\nspecial weapon for tearing his enemies or prey; it may, therefore,\nas far as its proper function is concerned, be considered as\nrudimentary. In every large collection of human skulls some may be\nfound, as Haeckel*(2) observes, with the canine teeth projecting\nconsiderably beyond the others in the same manner as in the\nanthropomorphous apes, but in a less degree. In these cases, open\nspaces between the teeth in the one jaw are left for the reception\nof the canines of the opposite jaw. An inter-space of this kind in a\nKaffir skull, figured by Wagner, is surprisingly wide.*(3) Considering\nhow few are the ancient skulls which have been examined, compared to\nrecent skulls, it is an interesting fact that in at least three\ncases the canines project largely; and in the Naulette jaw they are\nspoken of as enourmous.*(4)\n * Anatomy of Vertebrates, vol. iii., 1868, p. 323.\n *(2) Generelle Morphologie, 1866, B. ii., s. clv.\n *(3) Carl Vogt's Lectures on Man, Eng. translat., 1864, p. 151.\n *(4) C. Carter Blake, on a jaw from La Naulette, Anthropological\nReview, 1867, p. 295. Schaaffhausen, ibid., 1868, p. 426.\n Of the anthropomorphous apes the males alone have their canines\nfully developed; but in the female gorilla, and in a less degree in\nthe female orang, these teeth project considerably beyond the\nothers; therefore the fact, of which I have been assured, that women\nsometimes have considerably projecting canines, is no serious\nobjection to the belief that their occasional great development in man\nis a case of reversion to an ape-like progenitor. He who rejects\nwith scorn the belief that the shape of his own canines, and their\noccasional great development in other men, are due to our early\nforefathers having been provided with these formidable weapons, will\nprobably reveal, by sneering, the line of his descent. For though he\nno longer intends, nor has the power, to use these teeth as weapons,\nhe will unconsciously retract his \"snarling muscles\" (thus named by\nSir C. Bell),* so as to expose them ready for action, like a dog\nprepared to fight.\n * The Anatomy of Expression, 1844, pp. 110, 131.\n Many muscles are occasionally developed in man, which are proper\nto the Quadrumana or other mammals. Professor Vlacovich* examined\nforty male subjects, and found a muscle, called by him the\nischio-pubic, in nineteen of them; in three others there was a\nligament which represented this muscle; and in the remaining\neighteen no trace of it. In only two out of thirty female subjects was\nthis muscle developed on both sides, but in three others the\nrudimentary ligament was present. This muscle, therefore, appears to\nbe much more common in the male than in the female sex; and on the\nbelief in the descent of man from some lower form, the fact is\nintelligible; for it has been detected in several of the lower\nanimals, and in all of these it serves exclusively to aid the male\nin the act of reproduction.\n * Quoted by Prof. Canestrini in the Annuario, della Soc. dei\nNaturalisti, 1867, p. 90.\n Mr. J. Wood, in his valuable series of papers,* has minutely\ndescribed a vast number of muscular variations in man, which\nresemble normal structures in the lower animals. The muscles which\nclosely resemble those regularly present in our nearest allies, the\nQuadrumans, are too numerous to be here even specified. In a single\nmale subject, having a strong bodily frame, and well-formed skull,\nno less than seven muscular variations were observed, all of which\nplainly represented muscles proper to various kinds of apes. This man,\nfor instance, had on both sides of his neck a true and powerful\n\"levator claviculae,\" such as is found in all kinds of apes, and which\nis said to occur in about one out of sixty human subjects.*(2)\nAgain, this man had \"a special abductor of the metatarsal bone of\nthe fifth digit, such as Professor Huxley and Mr. Flower have shewn to\nexist uniformly in the higher and lower apes.\" I will give only two\nadditional cases; the acromio-basilar muscle is found in all mammals\nbelow man, and seems to be correlated with a quadrupedal gait,*(3) and\nit occurs in about one out of sixty human subjects. In the lower\nextremities Mr. Bradley*(4) found an abductor ossis metatarsi quinti\nin both feet of man; this muscle had not up to that time been recorded\nin mankind, but is always present in the anthropomorphous apes. The\nmuscles of the hands and arms- parts which are so eminently\ncharacteristic of man- are extremely liable to vary, so as to resemble\nthe corresponding muscles in the lower animals.*(5) Such\nresemblances are either perfect or imperfect; yet in the latter case\nthey are manifestly of a transitional nature. Certain variations are\nmore common in man, and others in woman, without our being able to\nassign any reason. Mr. Wood, after describing numerous variations,\nmakes the following pregnant remark. \"Notable departures from the\nordinary type of muscular structures run in grooves or directions,\nwhich must be taken to indicate some unknown factor, of much\nimportance to a comprehensive knowledge of general and scientific\nanatomy.\"*(6)\n * These papers deserve careful study by any one who desires to learn\nhow frequently our muscles vary, and in varying come to resemble those\nof the Quadrumana. The following references relate to the few points\ntouched on in my text: Proc. Royal Soc., vol. xiv., 1865, pp. 379-384;\nvol. xv., 1866, pp. 241, 242; vol. xv., 1867, p. 544; vol. xvi., 1868,\np. 524. I may here add that Dr. Murie and Mr. St. George Mivart have\nshewn in their Memoir on the Lemuroidea (Transactions, Zoological\nSociety, vol. vii., 1869, p. 96), how extraordinarily variable some of\nthe muscles are in these animals, the lowest members of the\nprimates. Gradations, also, in the muscles leading to structures found\nin animals still lower in the scale, are numerous in the Lemuroidea.\n *(2) See also Prof. Macalister in Proceedings, Royal Irish\nAcademy, vol. x., 1868, p. 124.\n *(3) Mr. Champneys in Journal of Anatomy and Physiology, Nov., 1871,\np. 178.\n *(4) Ibid., May, 1872, p. 421.\n *(5) Prof. Macalister (ibid., p. 121) has tabulated his\nobservations, and finds that muscular abnormalities are most\nfrequent in the fore-arms, secondly, in the face, thirdly, in the\nfoot, &c.\n *(6) The Rev. Dr. Haughton, after giving (Proc. R. Irish Academy,\nJune 27, 1864, p. 715) a remarkable case of variation in the human\nflexor pollicis longus, adds, \"This remarkable example shows that\nman may sometimes possess the arrangement of tendons of thumb and\nfingers characteristic of the macaque; but whether such a case\nshould be regarded as a macaque passing upwards into a man, or a man\npassing downwards into a macaque, or as a congenital freak of\nnature, I cannot undertake to say.\" It is satisfactory to hear so\ncapable an anatomist, and so embittered an opponent of evolutionism,\nadmitting even the possibility of either of his first propositions.\nProf. Macalister has also described (Proceedings Royal Irish\nAcademy, vol. x., 1864, p. 138) variations in the flexor pollicis\nlongus, remarkable from their relations to the same muscle in the\nQuadrumana.\n That this unknown factor is reversion to a former state of existence\nmay be admitted as in the highest degree probable.* It is quite\nincredible that a man should through mere accident abnormally resemble\ncertain apes in no less than seven of his muscles, if there had been\nno genetic connection between them. On the other hand, if man is\ndescended from some ape-like creature, no valid reason can be assigned\nwhy certain muscles should not suddenly reappear after an interval\nof many thousand generations, in the same manner as with horses,\nasses, and mules, dark-coloured stripes suddenly reappear on the legs,\nand shoulders, after an interval of hundreds, or more probably of\nthousands of generations.\n * Since the first edition of this book appeared, Mr. Wood has\npublished another memoir in the Philosophical Transactions, 1870, p.\n83, on the varieties of the muscles of the human neck, shoulder, and\nchest. He here shows how extremely variable these muscles are, and how\noften and how closely the variations resemble the normal muscles of\nthe lower animals. He sums up by remarking, \"It will be enough for\nmy purpose if I have succeeded in shewing the more important forms\nwhich, when occurring as varieties in the human subject, tend to\nexhibit in a sufficiently marked manner what may be considered as\nproofs and examples of the Darwinian principle of reversion, or law of\ninheritance, in this department of anatomical science.\"\n These various cases of reversion are so closely related to those\nof rudimentary organs given in the first chapter, that many of them\nmight have been indifferently introduced either there or here. Thus\na human uterus furnished with cornua may be said to represent, in a\nrudimentary condition, the same organ in its normal state in certain\nmammals. Some parts which are rudimentary in man, as the os coccyx\nin both sexes, and the mammae in the male sex, are always present;\nwhilst others, such as the supracondyloid foramen, only occasionally\nappear, and therefore might have been introduced under the head of\nreversion. These several reversionary structures, as well as the\nstrictly rudimentary ones, reveal the descent of man from some lower\nform in an unmistakable manner.\n Correlated Variation.- In man, as in the lower animals, many\nstructures are so intimately related, that when one part varies so\ndoes another, without our being able, in most cases, to assign any\nreason. We cannot say whether the one part governs the other, or\nwhether both are governed by some earlier developed part. Various\nmonstrosities, as I. Geoffroy repeatedly insists, are thus\nintimately connected. Homologous structures are particularly liable to\nchange together, as we see on the opposite sides of the body, and in\nthe upper and lower extremities. Meckel long ago remarked, that when\nthe muscles of the arm depart from their proper type, they almost\nalways imitate those of the leg; and so, conversely, with the\nmuscles of the legs. The organs of sight and hearing, the teeth and\nhair, the colour of the skin and of the hair, colour and constitution,\nare more or less correlated.* Professor Schaaffhausen first drew\nattention to the relation apparently existing between a muscular frame\nand the strongly-pronounced supra-orbital ridges, which are so\ncharacteristic of the lower races of man.\n * The authorities for these several statements are given in my\nVariation of Animals and Plants under Domestication, vol. ii., pp.\n320-335.\n Besides the variations which can be grouped with more or less\nprobability under the foregoing heads, there is a large class of\nvariations which may be provisionally called spontaneous, for to our\nignorance they appear to arise without any exciting cause. It can,\nhowever, be shewn that such variations, whether consisting of slight\nindividual differences, or of strongly-marked and abrupt deviations of\nstructure, depend much more on the constitution of the organism than\non the nature of the conditions to which it has been subjected.*\n * This whole subject has been discussed in chap. xxiii., vol. ii. of\nmy Variation of Animals and Plants under Domestication.\n Rate of Increase.- Civilised populations have been known under\nfavourable conditions, as in the United States, to double their\nnumbers in twenty-five years; and, according to a calculation, by\nEuler, this might occur in a little over twelve years.* At the\nformer rate, the present population of the United States (thirty\nmillions), would in 657 years cover the whole terraqueous globe so\nthickly, that four men would have to stand on each square yard of\nsurface. The primary or fundamental check to the continued increase of\nman is the difficulty of gaining subsistence, and of living in\ncomfort. We may infer that this is the case from what we see, for\ninstance, in the United States, where subsistence is easy, and there\nis plenty of room. If such means were suddenly doubled in Great\nBritain, our number would be quickly doubled. With civilised nations\nthis primary check acts chiefly by restraining marriages. The\ngreater death-rate of infants in the poorest classes is also very\nimportant; as well as the greater mortality, from various diseases, of\nthe inhabitants of crowded and miserable houses, at all ages. The\neffects of severe epidemics and wars are soon counterbalanced, and\nmore than counterbalanced, in nations placed under favourable\nconditions. Emigration also comes in aid as a temporary check, but,\nwith the extremely poor classes, not to any great extent.\n * See the ever memorable Essay on the Principle of Population, by\nthe Rev. T. Malthus, vol. i. 1826. pp. 6, 517.\n There is great reason to suspect, as Malthus has remarked, that\nthe reproductive power is actually less in barbarous, than in\ncivilised races. We know nothing positively on this head, for with\nsavages no census has been taken; but from the concurrent testimony of\nmissionaries, and of others who have long resided with such people, it\nappears that their families are usually small, and large ones rare.\nThis may be partly accounted for, as it is believed, by the women\nsuckling their infants during a long time; but it is highly probable\nthat savages, who often suffer much hardships, and who do not obtain\nso much nutritious food as civilised men, would be actually less\nprolific. I have shewn in a former work,* that all our domesticated\nquadrupeds and birds, and all our cultivated plants, are more\nfertile than the corresponding species in a state of nature. It is\nno valid objection to this conclusion that animals suddenly supplied\nwith an excess of food, or when grown very fat; and that most plants\non sudden removal from very poor to very rich soil, are rendered\nmore or less sterile. We might, therefore, expect that civilised\nmen, who in one sense are highly domesticated, would be more\nprolific than wild men. It is also probable that the increased\nfertility of civilised nations would become, as with our domestic\nanimals, an inherited character: it is at least known that with\nmankind a tendency to produce twins runs in families.*(2)\n * Variation of Animals and Plants under Domestication, vol ii.,\npp. 111-113, 163.\n *(2) Mr. Sedgwick, British and Foreign Medico-Chirurgical Review,\nJuly, 1863, p. 170.\n Notwithstanding that savages appear to be less prolific than\ncivilised people, they would no doubt rapidly increase if their\nnumbers were not by some means rigidly kept down. The Santali, or\nhill-tribes of India, have recently afforded a good illustration of\nthis fact; for, as shewn by Mr. Hunter,* they have increased at an\nextraordinary rate since vaccination has been introduced, other\npestilences mitigated, and war sternly repressed. This increase,\nhowever, would not have been possible had not these rude people spread\ninto the adjoining districts, and worked for hire. Savages almost\nalways marry; yet there is some prudential restraint, for they do\nnot commonly marry at the earliest possible age. The young men are\noften required to shew that they can support a wife; and they\ngenerally have first to earn the price with which to purchase her from\nher parents. With savages the difficulty of obtaining subsistence\noccasionally limits their number in a much more direct manner than\nwith civilised people, for all tribes periodically suffer from\nsevere famines. At such times savages are forced to devour much bad\nfood, and their health can hardly fail to be injured. Many accounts\nhave been published of their protruding stomachs and emaciated limbs\nafter and during famines. They are then, also, compelled to wander\nmuch, and, as I was assured in Australia, their infants perish in\nlarge numbers. As famines are periodical, depending chiefly on extreme\nseasons, all tribes must fluctuate in number. They cannot steadily and\nregularly increase, as there is no artificial increase in the supply\nof food. Savages, when hard pressed, encroach on each other's\nterritories, and war is the result; but they are indeed almost\nalways at war with their neighbours. They are liable to many accidents\non land and water in their search for food; and in some countries they\nsuffer much from the larger beasts of prey. Even in India, districts\nhave been depopulated by the ravages of tigers.\n * The Animals of Rural Bengal, by W. W. Hunter, 1868, p. 259.\n Malthus has discussed these several checks, but he does not lay\nstress enough on what is probably the most important of all, namely\ninfanticide, especially of female infants and the habit of procuring\nabortion. These practices now prevail in many quarters of the world;\nand infanticide seems formerly to have prevailed, as Mr. M'Lennan* has\nshewn on a still more extensive scale. These practices appear to\nhave originated in savages recognising the difficulty, or rather the\nimpossibility of supporting all the infants that are born.\nLicentiousness may also be added to the foregoing checks; but this\ndoes not follow from failing means of subsistence; though there is\nreason to believe that in some cases (as in Japan) it has been\nintentionally encouraged as a means of keeping down the population.\n * Primitive Marriage, 1865.\n If we look back to an extremely remote epoch, before man had arrived\nat the dignity of manhood, he would have been guided more by\ninstinct and less by reason than are the lowest savages at the present\ntime. Our early semi-human progenitors would not have practised\ninfanticide or polyandry; for the instincts of the lower animals are\nnever so perverted* as to lead them regularly to destroy their own\noffspring, or to be quite devoid of jealousy. There would have been no\nprudential restraint from marriage, and the sexes would have freely\nunited at an early age. Hence the progenitors of man would have tended\nto increase rapidly; but checks of some kind, either periodical or\nconstant, must have kept down their numbers, even more severely than\nwith existing savages. What the precise nature of these checks were,\nwe cannot say, any more than with most other animals. We know that\nhorses and cattle, which are not extremely prolific animals, when\nfirst turned loose in South America, increased at an enormous rate.\nThe elephant, the slowest breeder of all known animals, would in a few\nthousand years stock the whole world. The increase of every species of\nmonkey must be checked by some means; but not, as Brehm remarks, by\nthe attacks of beasts of prey. No one will assume that the actual\npower of reproduction in the wild horses and cattle of America, was at\nfirst in any sensible degree increased; or that, as each district\nbecame fully stocked, this same power was diminished. No doubt, in\nthis case, and in all others, many checks concur, and different checks\nunder different circumstances; periodical dearths, depending on\nunfavourable seasons, being probably the most important of all. So\nit will have been with the early progenitors of man.\n * A writer in the Spectator (March 12, 1871, p. 320) comments as\nfollows on this passage:- \"Mr. Darwin finds himself compelled to\nreintroduce a new doctrine of the fall of man. He shews that the\ninstincts of the higher animals are far nobler than the habits of\nsavage races of men, and he finds himself, therefore, compelled to\nre-introduce,- in a form of the substantial orthodoxy of which he\nappears to be quite unconscious,- and to introduce as a scientific\nhypothesis the doctrine that man's gain of knowledge was the cause\nof a temporary but long-enduring moral deterioration as indicated by\nthe many foul customs, especially as to marriage, of savage tribes.\nWhat does the Jewish tradition of the moral degeneration of man\nthrough his snatching at a knowledge forbidden him by his highest\ninstinct assert beyond this?\"\n Natural Selection.- We have now seen that man is variable in body\nand mind; and that the variations are induced, either directly or\nindirectly, by the same general causes, and obey the same general\nlaws, as with the lower animals. Man has spread widely over the face\nof the earth, and must have been exposed, during his incessant\nmigration,* to the most diversified conditions. The inhabitants of\nTierra del Fuego, the Cape of Good Hope, and Tasmania in the one\nhemisphere, and of the arctic regions in the other, must have passed\nthrough many climates, and changed their habits many times, before\nthey reached their present homes.*(2) The early progenitors of man\nmust also have tended, like all other animals, to have increased\nbeyond their means of subsistence; they must, therefore,\noccasionally have been exposed to a struggle for existence, and\nconsequently to the rigid law of natural selection. Beneficial\nvariations of all kinds will thus, either occasionally or\nhabitually, have been preserved and injurious ones eliminated. I do\nnot refer to strongly-marked deviations of structure, which occur only\nat long intervals of time, but to mere individual differences. We\nknow, for instance, that the muscles of our hands and feet, which\ndetermine our powers of movement, are liable, like those of the\nlower animals,*(3) to incessant variability. If then the progenitors\nof man inhabiting any district, especially one undergoing some\nchange in its conditions, were divided into two equal bodies, the\none half which included all the individuals best adapted by their\npowers of movement for gaining subsistence, or for defending\nthemselves, would on an average survive in greater numbers, and\nprocreate more offspring than the other and less well endowed half.\n * See some good remarks to this effect by W. Stanley Jevons, \"A\nDeduction from Darwin's Theory,\" Nature 1869, p. 231.\n *(2) Latham, Man and his Migrations, 1851, p. 135.\n *(3) Messrs. Murie and Mivart in their \"Anatomy of the Lemuroidea\"\n(Transact. Zoolog. Soc., vol. vii., 1869, pp. 96-98) say, \" some\nmuscles are so irregular in their distribution that they cannot be\nwell classed in any of the above groups.\" These muscles differ even on\nthe opposite sides of the same individual.\n Man in the rudest state in which he now exists is the most\ndominant animal that has ever appeared on this earth. He has spread\nmore widely than any other highly organised form: and all others\nhave yielded before him. He manifestly owes this immense superiority\nto his intellectual faculties, to his social habits, which lead him to\naid and defend his fellows, and to his corporeal structure. The\nsupreme importance of these characters has been proved by the final\narbitrament of the battle for life. Through his powers of intellect,\narticulate language has been evolved; and on this his wonderful\nadvancement has mainly depended. As Mr. Chauncey Wright remarks: \"A\npsychological analysis of the faculty of language shews, that even the\nsmallest proficiency in it might require more brain power than the\ngreatest proficiency in any other direction.\"* He has invented and\nis able to use various weapons, tools, traps, &c., with which he\ndefends himself, kills or catches prey, and otherwise obtains food. He\nhas made rafts or canoes for fishing or crossing over to\nneighbouring fertile islands. He has discovered the art of making\nfire, by which hard and stringy roots can be rendered digestible,\nand poisonous roots or herbs innocuous. This discovery of fire,\nprobably the greatest ever made by man, excepting language, dates from\nbefore the dawn of history. These several inventions, by which man\nin the rudest state has become so pre-eminent, are the direct\nresults of the development of his powers of observation, memory,\ncuriosity, imagination, and reason. I cannot, therefore, understand\nhow it is that Mr. Wallace*(2) maintains, that \"natural selection\ncould only have endowed the savage with a brain a little superior to\nthat of an ape.\"\n * \"Limits of Natural Selection,\" North American Review, Oct.,\n1870, p. 295.\n *(2) Quarterly Review, April, 1869, p. 392. This subject is more\nfully discussed in Mr. Wallace's Contributions to the Theory of\nNatural Selection, 1870, in which all the essays referred to in this\nwork are re-published. The \"Essay on Man,\" has been ably criticised by\nProf. Claparede, one of the most distinguished zoologists in Europe,\nin an article published in the Bibliotheque Universelle, June, 1870.\nThe remark quoted in my text will surprise every one who has read\nMr. Wallace's celebrated paper on \"The Origin of Human Races Deduced\nfrom the Theory of Natural Selection,\" originally published in the\nAnthropological Review, May, 1864, p. clviii. I cannot here resist\nquoting a most just remark by Sir J. Lubbock (Prehistoric Times, 1865,\np. 479) in reference to this paper, namely, that Mr. Wallace, \"with\ncharacteristic unselfishness, ascribes it (i. e. the idea of natural\nselection) unreservedly to Mr. Darwin, although, as is well known,\nhe struck out the idea independently, and published it, though not\nwith the same elaboration, at the same time.\"\n Although the intellectual powers and social habits of man are of\nparamount importance to him, we must not underrate the importance of\nhis bodily structure, to which subject the remainder of this chapter\nwill be devoted; the development of the intellectual and social or\nmoral faculties being discussed in a later chapter.\n Even to hammer with precision is no easy matter, as every one who\nhas tried to learn carpentry will admit. To throw a stone with as true\nan aim as a Fuegian in defending himself, or in killing birds,\nrequires the most consummate perfection in the correlated action of\nthe muscles of the hand, arm, and shoulder, and, further, a fine sense\nof touch. In throwing a stone or spear, and in many other actions, a\nman must stand firmly on his feet; and this again demands the\nperfect co-adaptation of numerous muscles. To chip a flint into the\nrudest tool, or to form a barbed spear or hook from a bone, demands\nthe use of a perfect hand; for, as a most capable judge, Mr.\nSchoolcraft,* remarks, the shaping fragments of stone into knives,\nlances, or arrow-heads, shews \"extraordinary ability and long\npractice.\" This is to a great extent proved by the fact that\nprimeval men practised a division of labour; each man did not\nmanufacture his own flint tools or rude pottery, but certain\nindividuals appear to have devoted themselves to such work, no doubt\nreceiving in exchange the produce of the chase. Archaeologists are\nconvinced that an enormous interval of time elapsed before our\nancestors thought of grinding chipped flints into smooth tools. One\ncan hardly doubt, that a man-like animal who possessed a hand and\narm sufficiently perfect to throw a stone with precision, or to form a\nflint into a rude tool, could, with sufficient practice, as far as\nmechanical skill alone is concerned, make almost anything which a\ncivilised man can make. The structure of the hand in this respect\nmay be compared with that of the vocal organs, which in the apes are\nused for uttering various signal-cries, or, as in one genus, musical\ncadences; but in man the closely similar vocal organs have become\nadapted through the inherited effects of use for the utterance of\narticulate language.\n * Quoted by Mr. Lawson Tait in his \"Law of Natural Selection,\"\nDublin Quarterly Journal of Medical Science, Feb., 1869. Dr. Keller is\nlikewise quoted to the same effect.\n Turning now to the nearest allies of men, and therefore to the\nbest representatives of our early progenitors, we find that the\nhands of the Quadrumana are constructed on the same general pattern as\nour own, but are far less perfectly adapted for diversified uses.\nTheir hands do not serve for locomotion so well as the feet of a\ndog; as may be seen in such monkeys as the chimpanzee and orang, which\nwalk on the outer margins of the palms, or on the knuckles.* Their\nhands, however, are admirably adapted for climbing trees. Monkeys\nseize thin branches or ropes, with the thumb on one side and the\nfingers and palm on the other, in the same manner as we do. They can\nthus also lift rather large objects, such as the neck of a bottle,\nto their mouths. Baboons turn over stones, and scratch up roots with\ntheir hands. They seize nuts, insects, or other small objects with the\nthumb in opposition to the fingers, and no doubt they thus extract\neggs and young from the nests of birds. American monkeys beat the wild\noranges on the branches until the rind is cracked, and then tear it\noff with the fingers of the two hands. In a wild state they break open\nhard fruits with stones. Other monkeys open mussel-shells with the two\nthumbs. With their fingers they pull out thorns and burs, and hunt for\neach other's parasites. They roll down stones, or throw them at\ntheir enemies: nevertheless, they are clumsy in these various actions,\nand, as I have myself seen, are quite unable to throw a stone with\nprecision.\n * Owen, Anatomy of Vertebrates, vol. iii., p. 71.\n It seems to me far from true that because \"objects are grasped\nclumsily\" by monkeys, \"a much less specialised organ of prehension\"\nwould have served them* equally well with their present hands. On\nthe contrary, I see no reason to doubt that more perfectly constructed\nhands would have been an advantage to them, provided that they were\nnot thus rendered less fitted for climbing trees. We may suspect\nthat a hand as perfect as that of man would have been\ndisadvantageous for climbing; for the most arboreal monkeys in the\nworld, namely, Ateles in America, Colobus in Africa, and Hylobates\nin Asia, are either thumbless, or their toes partially cohere, so that\ntheir limbs are converted into mere grasping hooks.*(2)\n * Quarterly Review, April, 1869, p. 392.\n *(2) In Hylobates syndactylus, as the name expresses, two of the\ntoes regularly cohere; and this, as Mr. Blyth informs me, is\noccasionally the case with the toes of H. agilis, lar, and\nleuciscus. Colobus is strictly arboreal and extraordinarily active\n(Brehm, Illustriertes Thierleben, B. i., s. 50), but whether a\nbetter climber than the species of the allied genera, I do not know.\nIt deserves notice that the feet of the sloths, the most arboreal\nanimals in the world, are wonderfully hooklike.\n As soon as some ancient member in the great series of the primates\ncame to be less arboreal, owing to a change in its manner of procuring\nsubsistence, or to some change in the surrounding conditions, its\nhabitual manner of progression would have been modified: and thus it\nwould have been rendered more strictly quadrupedal or bipedal. Baboons\nfrequent hilly and rocky districts, and only from necessity climb high\ntrees;* and they have acquired almost the gait of a dog. Man alone has\nbecome a biped; and we can, I think, partly see how he has come to\nassume his erect attitude, which forms one of his most conspicuous\ncharacters. Man could not have attained his present dominant\nposition in the world without the use of his hands, which are so\nadmirably adapted to act in obedience to his will. Sir C. Bell*(2)\ninsists that \"the hand supplies all instruments, and by its\ncorrespondence with the intellect gives him universal dominion.\" But\nthe hands and arms could hardly have become perfect enough to have\nmanufactured weapons, or to have hurled stones and spears with a\ntrue aim, as long as they were habitually used for locomotion and\nfor supporting the whole weight of the body, or, as before remarked,\nso long as they were especially fitted for climbing trees. Such\nrough treatment would also have blunted the sense of touch, on which\ntheir delicate use largely depends. From these causes alone it would\nhave been an advantage to man to become a biped; but for many\nactions it is indispensable that the arms and whole upper part of\nthe body should be free; and he must for this end stand firmly on\nhis feet. To gain this great advantage, the feet have been rendered\nflat; and the great toe has been peculiarly modified, though this\nhas entailed the almost complete loss of its power of prehension. It\naccords with the principle of the division of physiological labour,\nprevailing throughout the animal kingdom, that as the hands became\nperfected for prehension, the feet should have become perfected for\nsupport and locomotion. With some savages, however, the foot has not\naltogether lost its prehensile power, as shewn by their manner of\nclimbing trees, and of using them in other ways.*(3)\n * Brehm, Illustriertes Thierleben, B. i., s. 80.\n *(2) \"The Hand,\" &c., Bridgewater Treatise, 1833, p. 38.\n *(3) Haeckel has an excellent discussion on the steps by which\nman became a biped: Naturliche Schopfungsgeschicte, 1868, s. 507.\nDr. Buchner (Conferences sur la Theorie Darwinienne, 1869, p. 135) has\ngiven good cases of the use of the foot as a prehensile organ by\nman; and has also written on the manner of progression of the higher\napes, to which I allude in the following paragraph: see also Owen\n(Anatomy of Vertebrates, vol. iii., p. 71) on this latter subject.\n If it be an advantage to man to stand firmly on his feet and to have\nhis hands and arms free, of which, from his pre-eminent success in the\nbattle of life, there can be no doubt, then I can see no reason why it\nshould not have been advantageous to the progenitors of man to have\nbecome more and more erect or bipedal. They would thus have been\nbetter able to defend themselves with stones or clubs, to attack their\nprey, or otherwise to obtain food. The best built individuals would in\nthe long run have succeeded best, and have survived in larger numbers.\nIf the gorilla and a few allied forms had become extinct, it might\nhave been argued, with great force and apparent truth, that an\nanimal could not have been gradually converted from a quadruped into a\nbiped, as all the individuals in an intermediate condition would\nhave been miserably ill-fitted for progression. But we know (and\nthis is well worthy of reflection) that the anthropomorphous apes\nare now actually in an intermediate condition; and no one doubts\nthat they are on the whole well adapted for their conditions of\nlife. Thus the gorilla runs with a sidelong shambling gait, but more\ncommonly progresses by resting on its bent hands. The long-armed\napes occasionally use their arms like crutches, swinging their\nbodies forward between them, and some kinds of Hylobates, without\nhaving been taught, can walk or run upright with tolerable\nquickness; yet they move awkwardly, and much less securely than man.\nWe see, in short, in existing monkeys a manner of progression\nintermediate between that of a quadruped and a biped; but, as an\nunprejudiced judge* insists, the anthropomorphous apes approach in\nstructure more nearly to the bipedal than to the quadrupedal type.\n * Prof. Broca, \"La Constitution des vertebres caudales\"; La Revue\nd'Anthropologie, 1872, p. 26, (separate copy).\n As the progenitors of man became more and more erect, with their\nhands and arms more and more modified for prehension and other\npurposes, with their feet and legs at the same time transformed for\nfirm support and progression, endless other changes of structure would\nhave become necessary. The pelvis would have to be broadened, the\nspine peculiarly curved, and the head fixed in an altered position,\nall which changes have been attained by man. Prof. Schaaffhausen*\nmaintains that \"the powerful mastoid processes of the human skull\nare the result of his erect position\"; and these processes are\nabsent in the orang, chimpanzee, &c., and are smaller in the gorilla\nthan in man. Various other structures, which appear connected with\nman's erect position, might here have been added. It is very difficult\nto decide how far these correlated modifications are the result of\nnatural selection, and how far of the inherited effects of the\nincreased use of certain parts, or of the action of one part on\nanother. No doubt these means of change often co-operate: thus when\ncertain muscles, and the crests of bone to which they are attached,\nbecome enlarged by habitual use, this shews that certain actions are\nhabitually performed and must be serviceable. Hence the individuals\nwhich performed them best, would tend to survive in greater numbers.\n * \"On the Primitive Form of the Skull,\" translated in\nAnthropological Review, Oct., 1868, p. 428. Owen (Anatomy of\nVertebrates, vol. ii., 1866, p. 551) on the mastoid processes in the\nhigher apes.\n The free use of the arms and hands, partly the cause and partly\nthe result of man's erect position, appears to have led in an indirect\nmanner to other modifications of structure. The early male forefathers\nof man were, as previously stated, probably furnished with great\ncanine teeth; but as they gradually acquired the habit of using\nstones, clubs, or other weapons, for fighting with their enemies or\nrivals, they would use their jaws and teeth less and less. In this\ncase, the jaws, together with the teeth, would become reduced in size,\nas we may feel almost sure from innumerable analogous cases. In a\nfuture chapter we shall meet with a closely parallel case, in the\nreduction or complete disappearance of the canine teeth in male\nruminants, apparently in relation with the development of their horns;\nand in horses, in relation to their habit of fighting with their\nincisor teeth and hoofs.\n In the adult male anthropomorphous apes, as Rutimeyer,* and\nothers, have insisted, it is the effect on the skull of the great\ndevelopment of the jaw-muscles that causes it to differ so greatly\nin many respects from that of man, and has given to these animals \"a\ntruly frightful physiognomy.\" Therefore, as the jaws and teeth in\nman's progenitors gradually become reduced in size, the adult skull\nwould have come to resemble more and more that of existing man. As\nwe shall hereafter see, a great reduction of the canine teeth in the\nmales would almost certainly affect the teeth of the females through\ninheritance.\n * Die Grenzen der Thierwelt, eine Betrachtung zu Darwin's Lehre,\n1868, s. 51.\n As the various mental faculties gradually developed themselves the\nbrain would almost certainly become larger. No one, I presume,\ndoubts that the large proportion which the size of man's brain bears\nto his body, compared to the same proportion in the gorilla or\norang, is closely connected with his higher mental powers. We meet\nwith closely analogous facts with insects, for in ants the cerebral\nganglia are of extraordinary dimensions, and in all the Hymenoptera\nthese ganglia are many times larger than in the less intelligent\norders, such as beetles.* On the other hand, no one supposes that\nthe intellect of any two animals or of any two men can be accurately\ngauged by the cubic contents of their skulls. It is certain that there\nmay be extraordinary mental activity with an extremely small\nabsolute mass of nervous matter: thus the wonderfully diversified\ninstincts, mental powers, and affections of ants are notorious, yet\ntheir cerebral ganglia are not so large as the quarter of a small\npin's head. Under this point of view, the brain of an ant is one of\nthe most marvellous atoms of matter in the world, perhaps more so than\nthe brain of a man.\n * Dujardin, Annales des Sciences Nat., 3rd series, Zoolog., tom.\nxiv., 1850, p. 203. See also Mr. Lowne, Anatomy and Phys. of the Musca\nvomitoria, 1870, p. 14. My son, Mr. F. Darwin, dissected for me the\ncerebral ganglia of the Formica rufa.\n The belief that there exists in man some close relation between\nthe size of the brain and the development of the intellectual\nfaculties is supported by the comparison of the skulls of savage and\ncivilised races, of ancient and modern people, and by the analogy of\nthe whole vertebrate series. Dr. J. Barnard Davis has proved,* by many\ncareful measurements, that the mean internal capacity of the skull\nin Europeans is 92.3 cubic inches; in Americans 87.5; in Asiatics\n87.1; and in Australians only 81.9 cubic inches. Professor Broca*(2)\nfound that the nineteenth century skulls from graves in Paris were\nlarger than those from vaults of the twelfth century, in the\nproportion of 1484 to 1426; and that the increased size, as\nascertained by measurements, was exclusively in the frontal part of\nthe skull- the seat of the intellectual faculties. Prichard is\npersuaded that the present inhabitants of Britain have \"much more\ncapacious braincases\" than the ancient inhabitants. Nevertheless, it\nmust be admitted that some skulls of very high antiquity, such as\nthe famous one of Neanderthal, are well developed and capacious.*(3)\nWith respect to the lower animals, M. E. Lartet,*(4) by comparing\nthe crania of tertiary and recent mammals belonging to the same\ngroups, has come to the remarkable conclusion that the brain is\ngenerally larger and the convolutions are more complex in the more\nrecent forms. On the other hand, I have shewn*(5) that the brains of\ndomestic rabbits are considerably reduced in bulk, in comparison\nwith those of the wild rabbit or hare; and this may be attributed to\ntheir having been closely confined during many generations, so that\nthey have exerted their intellect, instincts, senses and voluntary\nmovements but little.\n * Philosophical Transactions, 1869, p. 513.\n *(2) \"Les Selections,\" M. P. Broca, Revue d'Anthropologie,, 1873;\nsee also, as quoted in C. Vogt's Lectures on Man, Engl. translat.,\n1864, pp. 88, 90. Prichard, Physical History of Mankind, vol. i.,\n1838, p. 305.\n *(3) In the interesting article just referred to, Prof. Broca has\nwell remarked, that in civilised nations, the average capacity of\nthe skull must be lowered by the preservation of a considerable number\nof individuals, weak in mind and body, who would have been promptly\neliminated in the savage state. On the other hand, with savages, the\naverage includes only the more capable individuals, who have been able\nto survive under extremely hard conditions of life. Broca thus\nexplains the otherwise inexplicable fact, that the mean capacity of\nthe skull of the ancient troglodytes of Lozere is greater than that of\nmodern Frenchmen.\n *(4) Comptes-rendus des Sciences, &c., June 1, 1868.\n *(5) The Variation of Animals and Plants under Domestication, vol.\ni., pp. 124-129.\n The gradually increasing weight of the brain and skull in man must\nhave influenced the development of the supporting spinal column,\nmore especially whilst he was becoming erect. As this change of\nposition was being brought about, the internal pressure of the brain\nwill also have influenced the form of the skull; for many facts shew\nhow easily the skull is thus effected. Ethnologists believe that it is\nmodified by the kind of cradle in which infants sleep. Habitual spasms\nof the muscles, and a cicatrix from a severe burn, have permanently\nmodified the facial bones. In young persons whose heads have become\nfixed either sideways or backwards, owing to disease, one of the two\neyes has changed its position, and the shape of the skull has been\naltered apparently by the pressure of the brain in a new direction.* I\nhave shewn that with long-eared rabbits even so trifling a cause as\nthe lopping forward of one ear drags forward almost every bone of\nthe skull on that side; so that the bones on the opposite side no\nlonger strictly correspond. Lastly, if any animal were to increase\nor diminish much in general size, without any change in its mental\npowers, or if the mental powers were to be much increased or\ndiminished, without any great change in the size of the body, the\nshape of the skull would almost certainly be altered. I infer this\nfrom my observations on domestic rabbits, some kinds of which have\nbecome very much larger than the wild animal, whilst others have\nretained nearly the same size, but in both cases the brain has been\nmuch reduced relatively to the size of the body. Now I was at first\nmuch surprised on finding that in all these rabbits the skull had\nbecome elongated or dolichocephalic; for instance, of two skulls of\nnearly equal breadth, the one from a wild rabbit and the other from\na large domestic kind, the former was 3.15 and the latter 4.3 inches\nin length.*(2) One of the most marked distinctions in different\nraces of men is that the skull in some is elongated, and in others\nrounded; and here the explanation suggested by the case of the rabbits\nmay hold good; for Welcker finds that short \"men incline more to\nbrachycephaly, and tall men to dolichocephaly\";*(3) and tall men may\nbe compared with the larger and longer-bodied rabbits, all of which\nhave elongated skulls or are dolichocephalic.\n * Schaaffhausen gives from Blumenbach and Busch, the cases of the\nspasms and cicatrix in Anthropological Review, Oct., 1868, p. 420. Dr.\nJarrold (Anthropologia, 1808, pp. 115, 116) adduces from Camper and\nfrom his own observations, cases of the modification of the skull from\nthe head being fixed in an unnatural position. He believes that in\ncertain trades, such as that of a shoemaker, where the head is\nhabitually held forward, the forehead becomes more rounded and\nprominent.\n *(2) Variation of Animals and Plants under Domestication, vol. i.,\np. 117, on the elongation of the skull; p. 119, on the effect of the\nlopping of one ear.\n *(3) Quoted by Schaaffhausen, in Anthropological Review, Oct., 1868,\np. 419.\n From these several facts we can understand, to a certain extent, the\nmeans by which the great size and more or less rounded form of the\nskull have been acquired by man; and these are characters eminently\ndistinctive of him in comparison with the lower animals.\n Another most conspicuous difference between man and the lower\nanimals is the nakedness of his skin. Whales and porpoises\n(Cetacea), dugongs (Sirenia) and the hippopotamus are naked; and\nthis may be advantageous to them for gliding through the water; nor\nwould it be injurious to them from the loss of warmth, as the species,\nwhich inhabit the colder regions, are protected by a thick layer of\nblubber, serving the same purpose as the fur of seals and otters.\nElephants and rhinoceroses are almost hairless; and as certain extinct\nspecies, which formerly lived under an arctic climate, were covered\nwith long wool or hair, it would almost appear as if the existing\nspecies of both genera had lost their hairy covering from exposure\nto heat. This appears the more probable, as the elephants in India\nwhich live on elevated and cool districts are more hairy* than those\non the lowlands. May we then infer that man became divested of hair\nfrom having aboriginally inhabited some tropical land? That the hair\nis chiefly retained in the male sex on the chest and face, and in both\nsexes at the junction of all four limbs with the trunk, favours this\ninference- on the assumption that the hair was lost before man\nbecame erect; for the parts which now retain most hair would then have\nbeen most protected from the heat of the sun. The crown of the head,\nhowever, offers a curious exception, for at all times it must have\nbeen one of the most exposed parts, yet it is thickly clothed with\nhair. The fact, however, that the other members of the order of\nprimates, to which man belongs, although inhabiting various hot\nregions, are well clothed with hair, generally thickest on the upper\nsurface,*(2) is opposed to the supposition that man became naked\nthrough the action of the sun. Mr. Belt believes*(3) that within the\ntropies it is an advantage to man to be destitute of hair, as he is\nthus enabled to free himself of the multitude of ticks (acari) and\nother parasites, with which he is often infested, and which\nsometimes cause ulceration. But whether this evil is of sufficient\nmagnitude to have led to the denudation of his body through natural\nselection, may be doubted, since none of the many quadrupeds\ninhabiting the tropics have, as far as I know, acquired any\nspecialised means of relief. The view which seems to me the most\nprobable is that man, or rather primarily woman, became divested of\nhair for ornamental purposes, as we shall see under Sexual\nSelection; and, according to this belief, it is not surprising that\nman should differ so greatly in hairiness from all other primates, for\ncharacters, gained through sexual selection, often differ to an\nextraordinary degree in closely related forms.\n * Owen, Anatomy of Vertebrates, vol. iii., p. 619.\n *(2) Isidore Geoffroy St-Hilaire remarks (Histoire Nat. Generale,\ntom. ii., 1859, pp. 215-217) on the head of man being covered with\nlong hair; also on the upper surfaces of monkeys and of other\nmammals being more thickly clothed than the lower surfaces. This has\nlikewise been observed by various authors. Prof. P. Gervais\n(Histoire Nat. des Mammiferes, tom. i., 1854, p. 28), however,\nstates that in the gorilla the hair is thinner on the back, where it\nis partly rubbed off, than on the lower surface.\n *(3) The Naturalist in Nicaragua, 1874, p. 209. As some confirmation\nof Mr. Belt's view, I may quote the following passage from Sir W.\nDenison (Varieties of Vice-Regal Life, vol. i., 1870, p. 440): \"It\nis said to be a practice with the Australians, when the vermin get\ntroublesome, to singe themselves.\"\n According to a popular impression, the absence of a tail is\neminently distinctive of man; but as those apes which come nearest\nto him are destitute of this organ, its disappearance does not\nrelate exclusively to man. The tail often differs remarkably in length\nwithin the same genus: thus in some species of Macacus it is longer\nthan the whole body, and is formed of twenty-four vertebrae; in others\nit consists of a scarcely visible stump, containing only three or four\nvertebrae. In some kinds of baboons there are twenty-five, whilst in\nthe mandrill there are ten very small stunted caudal vertebrae, or,\naccording to Cuvier,* sometimes only five. The tail, whether it be\nlong or short, almost always tapers towards the end; and this, I\npresume, results from the atrophy of the terminal muscles, together\nwith their arteries and nerves, through disuse, leading to the atrophy\nof the terminal bones. But no explanation can at present be given of\nthe great diversity which often occurs in its length. Here, however,\nwe are more specially concerned with the complete external\ndisappearance of the tail. Professor Broca has recently shewn*(2) that\nthe tail in all quadrupeds consists of two portions, generally\nseparated abruptly from each other; the basal portion consists of\nvertebrae, more or less perfectly channelled and furnished with\napophyses like ordinary vertebrae; whereas those of the terminal\nportion are not channelled, are almost smooth, and scarcely resemble\ntrue vertebrae. A tail, though not externally visible, is really\npresent in man and the anthropomorphous apes, and is constructed on\nexactly the same pattern in both. In the terminal portion the\nvertabrae, constituting the os coccyx, are quite rudimentary, being\nmuch reduced in size and number. In the basal portion, the vertebrae\nare likewise few, are united firmly together, and are arrested in\ndevelopment; but they have been rendered much broader and flatter than\nthe corresponding vertebrae in the tails of other animals: they\nconstitute what Broca calls the accessory sacral vertebrae. These\nare of functional importance by supporting certain internal parts\nand in other ways; and their modification is directly connected with\nthe erect or semi-erect attitude of man and the anthropomorphous apes.\nThis conclusion is the more trustworthy, as Broca formerly held a\ndifferent view, which he has now abandoned. The modification,\ntherefore, of the basal caudal vertebrae in man and the higher apes\nmay have been effected, directly or indirectly, through natural\nselection.\n * Mr. St. George Mivart, Proc. Zoolog. Soc., 1865, pp. 562, 583. Dr.\nJ. E. Gray, Cat. Brit. Mus: \" Skeletons.\" Owen, Anatomy of\nVertebrates, vol. ii., p. 517. Isidore Geoffroy, Hist. Nat. Gen., tom.\nii., p. 244.\n *(2) Revue d'Anthropologie, 1872; \"La Constitution des vertebres\ncaudales.\"\n But what are we to say about the rudimentary and variable\nvertebrae of the terminal portion of the tail, forming the os\ncoccyx? A notion which has often been, and will no doubt again be\nridiculed, namely, that friction has had something to do with the\ndisappearance of the external portion of the tail, is not so\nridiculous as it at first appears. Dr. Anderson* states that the\nextremely short tail of Macacus brunneus is formed of eleven\nvertebrae, including the imbedded basal ones. The extremity is\ntendinous and contains no vertebrae; this is succeeded by five\nrudimentary ones, so minute that together they are only one line and a\nhalf in length, and these are permanently bent to one side in the\nshape of a hook. The free part of the tail, only a little above an\ninch in length, includes only four more small vertebrae. This short\ntail is carried erect; but about a quarter of its total length is\ndoubled on to itself to the left; and this terminal part, which\nincludes the hook-like portion, serves \"to fill up the interspace\nbetween the upper divergent portion of the callosities\"; so that the\nanimal sits on it, and thus renders it rough and callous. Dr. Anderson\nthus sums up his observations: \"These facts seem to me to have only\none explanation; this tail, from its short size, is in the monkey's\nway when it sits down, and frequently becomes placed under the\nanimal while it is in this attitude; and from the circumstance that it\ndoes not extend beyond the extremity of the ischial tuberosities, it\nseems as if the tail originally had been bent round by the will of the\nanimal, into the interspace between the callosities, to escape being\npressed between them and the ground, and that in time the curvature\nbecame permanent, fitting in of itself when the organ happens. to be\nsat upon.\" Under these circumstances it is not surprising that the\nsurface of the tail should have been roughened and rendered callous,\nand Dr. Murie,*(2) who carefully observed this species in the\nZoological Gardens, as well as three other closely allied forms with\nslightly longer tails, says that when the animal sits down, the tail\n\"is necessarily thrust to one side of the buttocks; and whether long\nor short its root is consequently liable to be rubbed or chafed.\" As\nwe now have evidence that mutilations occasionally produce an\ninherited effect,*(3) it is not very improbable that in short-tailed\nmonkeys, the projecting part of the tail, being functionally\nuseless, should after many generations have become rudimentary and\ndistorted, from being continually rubbed and chafed. We see the\nprojecting part in this condition in the Macacus brunneus, and\nabsolutely aborted in the M. ecaudatus and in several of the higher\napes. Finally, then, as far as we can judge, the tail has\ndisappeared in man and the anthropomorphous apes, owing to the\nterminal portion having been injured by friction during a long lapse\nof time; the basal and embedded portion having been reduced and\nmodified, so as to become suitable to the erect or semi-erect\nposition.\n * Proceedings Zoological Society, 1872, p. 210.\n *(2) Proceedings Zoological Society, 1872, p. 786.\n *(3) I allude to Dr. Brown-Sequard's observations on the transmitted\neffect of an operation causing epilepsy in guinea-pigs, and likewise\nmore recently on the analogous effects of cutting the sympathetic\nnerve in the neck. I shall hereafter have occasion to refer to Mr.\nSalvin's interesting case of the apparently inherited effects of\nmotmots biting off the barbs of their own tail-feathers. See also on\nthe general subject Variation of Animals and Plants under\nDomestication, vol. ii., pp. 22-24.\n I have now endeavoured to shew that some of the most distinctive\ncharacters of man have in all probability been acquired, either\ndirectly, or more commonly indirectly, through natural selection. We\nshould bear in mind that modifications in structure or constitution\nwhich do not serve to adapt an organism to its habits of life, to\nthe food which it consumes, or passively to the surrounding\nconditions, cannot have been thus acquired. We must not, however, be\ntoo confident in deciding what modifications are of service to each\nbeing: we should remember how little we know about the use of many\nparts, or what changes in the blood or tissues may serve to fit an\norganism for a new climate or new kinds of food. Nor must we forget\nthe principle of correlation, by which, as Isidore Geoffroy has\nshewn in the case of man, many strange deviations of structure are\ntied together. Independently of correlation, a change in one part\noften leads, through the increased or decreased use of other parts, to\nother changes of a quite unexpected nature. It is also well to reflect\non such facts, as the wonderful growth of galls on plants caused by\nthe poison of an insect, and on the remarkable changes of colour in\nthe plumage of parrots when fed on certain fishes, or inoculated\nwith the poison of toads;* for we can thus see that the fluids of\nthe system, if altered for some special purpose, might induce other\nchanges. We should especially bear in mind that modifications acquired\nand continually used during past ages for some useful purpose, would\nprobably become firmly fixed, and might be long inherited.\n * The Variation of Animals and Plants under Domestication, vol. ii.,\npp. 280, 282.\n Thus a large yet undefined extension may safely be given to the\ndirect and indirect results of natural selection; but I now admit,\nafter reading the essay by Nageli on plants, and the remarks by\nvarious authors with respect to animals, more especially those\nrecently made by Professor Broca, that in the earlier editions of my\nOrigin of Species I perhaps attributed too much to the action of\nnatural selection or the survival of the fittest. I have altered the\nfifth edition of the Origin so as to confine my remarks to adaptive\nchanges of structure; but I am convinced, from the light gained during\neven the last few years, that very many structures which now appear to\nus useless, will hereafter be proved to be useful, and will\ntherefore come within the range of natural selection. Nevertheless,\nI did not formerly consider sufficiently the existence of\nstructures, which, as far as we can at present judge, are neither\nbeneficial nor injurious; and this I believe to be one of the greatest\noversights as yet detected in my work. I may be permitted to say, as\nsome excuse, that I had two distinct objects in view; firstly, to shew\nthat species had not been separately created, and secondly, that\nnatural selection had been the chief agent of change, though largely\naided by the inherited effects of habit, and slightly by the direct\naction of the surrounding conditions. I was not, however, able to\nannul the influence of my former belief, then almost universal, that\neach species had been purposely created; and this led to my tacit\nassumption that every detail of structure, excepting rudiments, was of\nsome special, though unrecognised, service. Any one with this\nassumption in his mind would naturally extend too far the action of\nnatural selection, either during past or present times. Some of\nthose who admit the principle of evolution, but reject natural\nselection, seem to forget, when criticising my book, that I had the\nabove two objects in view; hence if I have erred in giving to\nnatural selection great power, which I am very far from admitting,\nor in having exaggerated its power, which is in itself probable, I\nhave at least, as I hope, done good service in aiding to overthrow the\ndogma of separate creations.\n It is, as I can now see, probable that all organic beings, including\nman, possess peculiarities of structure, which neither are now, nor\nwere formerly of any service to them, and which, therefore, are of\nno physiological importance. We know not what produces the\nnumberless slight differences between the individuals of each species,\nfor reversion only carries the problem a few steps backwards, but each\npeculiarity must have had its efficient cause. If these causes,\nwhatever they may be, were to act more uniformly and energetically\nduring a lengthened period (and against this no reason can be\nassigned), the result would probably be not a mere slight individual\ndifference, but a well-marked and constant modification, though one of\nno physiological importance. Changed structures, which are in no way\nbeneficial, cannot be kept uniform through natural selection, though\nthe injurious will be thus eliminated. Uniformity of character\nwould, however, naturally follow from the assumed uniformity of the\nexciting causes, and likewise from the free intercrossing of many\nindividuals. During successive periods, the same organism might in\nthis manner acquire successive modifications, which would be\ntransmitted in a nearly uniform state as long as the exciting causes\nremained the same and there was free intercrossing. With respect to\nthe exciting causes we can only say, as when speaking of so-called\nspontaneous variations, that they relate much more closely to the\nconstitution of the varying organism, than to the nature of the\nconditions to which it has been subjected.\n Conclusion.- In this chapter we have seen that as man at the present\nday is liable, like every other animal, to multiform individual\ndifferences or slight variations, so no doubt were the early\nprogenitors of man; the variations being formerly induced by the\nsame general causes, and governed by the same general and complex laws\nas at present. As all animals tend to multiply beyond their means of\nsubsistence, so it must have been with the progenitors of man; and\nthis would inevitably lead to a struggle for existence and to\nnatural selection. The latter process would be greatly aided by the\ninherited effects of the increased use of parts, and these two\nprocesses would incessantly react on each other. It appears, also,\nas we shall hereafter see, that various unimportant characters have\nbeen acquired by man through sexual selection. An unexplained residuum\nof change must be left to the assumed uniform action of those\nunknown agencies, which occasionally induce strongly marked and abrupt\ndeviations of structure in our domestic productions.\n Judging from the habits of savages and of the greater number of\nthe Quadrumana, primeval men, and even their ape-like progenitors,\nprobably lived in society. With strictly social animals, natural\nselection sometimes acts on the individual, through the preservation\nof variations which are beneficial to the community. A community which\nincludes a large number of well-endowed individuals increases in\nnumber, and is victorious over other less favoured ones; even although\neach separate member gains no advantage over the others of the same\ncommunity. Associated insects have thus acquired many remarkable\nstructures, which are of little or no service to the individual,\nsuch as the pollen-collecting apparatus, or the sting of the\nworker-bee, or the great jaws of soldier-ants. With the higher\nsocial animals, I am not aware that any structure has been modified\nsolely for the good of the community, though some are of secondary\nservice to it. For instance, the horns of ruminants and the great\ncanine teeth of baboons appear to have been acquired by the males as\nweapons for sexual strife, but they are used in defence of the herd or\ntroop. In regard to certain mental powers the case, as we shall see in\nthe fifth chapter, is wholly different; for these faculties have\nbeen chiefly, or even exclusively, gained for the benefit of the\ncommunity, and the individuals thereof have at the same time gained an\nadvantage indirectly.\n It has often been objected to such views as the foregoing, that\nman is one of the most helpless and defenceless creatures in the\nworld; and that during his early and less well-developed condition, he\nwould have been still more helpless. The Duke of Argyll, for instance,\ninsists* that \"the human frame has diverged from the structure of\nbrutes, in the direction of greater physical helplessness and\nweakness. That is to say, it is a divergence which of all others it is\nmost impossible to ascribe to mere natural selection.\" He adduces\nthe naked and unprotected state of the body, the absence of great\nteeth or claws for defence, the small strength and speed of man, and\nhis slight power of discovering food or of avoiding danger by smell.\nTo these deficiencies there might be added one still more serious,\nnamely, that he cannot climb quickly, and so escape from enemies.\nThe loss of hair would not have been a great injury to the inhabitants\nof a warm country. For we know that the unclothed Fuegians can exist\nunder a wretched climate. When we compare the defenceless state of man\nwith that of apes, we must remember that the great canine teeth with\nwhich the latter are provided, are possessed in their full development\nby the males alone, and are chiefly used by them for fighting with\ntheir rivals; yet the females, which are not thus provided, manage\nto survive.\n * Primeval Man, 1869, p. 66.\n In regard to bodily size or strength, we do not know whether man\nis descended from some small species, like the chimpanzee, or from one\nas powerful as the gorilla; and, therefore, we cannot say whether\nman has become larger and stronger, or smaller and weaker, than his\nancestors. We should, however, bear in mind that an animal\npossessing great size, strength, and ferocity, and which, like the\ngorilla, could defend itself from all enemies, would not perhaps\nhave become social: and this would most effectually have checked the\nacquirement of the higher mental qualities, such as sympathy and the\nlove of his fellows. Hence it might have been an immense advantage\nto man to have sprung from some comparatively weak creature.\n The small strength and speed of man, his want of natural weapons,\n&c., are more than counterbalanced, firstly, by his intellectual\npowers, through which he has formed for himself weapons, tools, &c.,\nthough still remaining in a barbarous state, and, secondly, by his\nsocial qualities which lead him to give and receive aid from his\nfellow-men. No country in the world abounds in a greater degree with\ndangerous beasts than southern Africa; no country presents more\nfearful physical hardships than the arctic regions; yet one of the\npuniest of races, that of the bushmen, maintains itself in southern\nAfrica, as do the dwarfed Esquimaux in the arctic regions. The\nancestors of man were, no doubt, inferior in intellect, and probably\nin social disposition, to the lowest existing savages; but it is quite\nconceivable that they might have existed, or even flourished, if\nthey had advanced in intellect, whilst gradually losing their\nbrute-like powers such as that of climbing trees, &c. But these\nancestors would not have been exposed to any special danger, even if\nfar more helpless and defenceless than any existing savages, had\nthey inhabited some warm continent or large island, such as Australia,\nNew Guinea, or Borneo, which is now the home of the orang. And natural\nselection arising from the competition of tribe with tribe, in some\nsuch large area as one of these, together with the inherited effects\nof habit, would, under favourable conditions, have sufficed to raise\nman to his present high position in the organic scale.","title":"Chapter II - On the Manner of Development of Man from some Lower Form","type":"page"}