variations supervening at a rather late embryonic period, and being inherited at a corresponding period, how it is that the embryos of wonderfully different forms should still retain, more or less perfectly, the structure of their common progenitor. No other explanation has ever been given of the marvellous fact that the embryos of a man, dog, seal, bat, reptile, &c., can at first hardly be distinguished from each other. In order to understand the existence of rudimentary organs, we have only to suppose that a former progenitor possessed the parts in question in a perfect state, and that under changed habits of life they became greatly reduced, either from simple disuse, or through the natural selection of those individuals which were least encumbered with a superfluous part, aided by the other means previously indicated. Thus we can understand how it has come to pass that man and all other vertebrate animals have been constructed on the same general model, why they pass through the same early stages of development, and why they retain certain rudiments in common. Consequently we ought frankly to admit their community of descent; to take any other view, is to admit that our own structure, and that of all the animals around us, is a mere snare laid to entrap our judgment. This conclusion is greatly strengthened, if we look to the members of the whole animal series, and consider the evidence derived from their affinities or classification, their geographical distribution and geological succession. It is only our natural prejudice, and that arrogance which made our forefathers declare that they were descended from demi-gods, which leads us to demur to this conclusion. But the time will before long come, when it will be thought wonderful that naturalists, who were well acquainted with the comparative structure and development of man, and other mammals, should have believed that each was the work of a separate act of creation. CHAPTER II. ON THE MAN FER OF DEVELOPMENT OF MAN FROM SOME Variability of body and mind in man-Inheritance-Causes of variability -Laws of variation the same in man as in the lower animals-Direct action of the conditions of life-Effects of the increased use and disuse of parts-Arrested development-Reversion-Correlated variationRate of increase-Checks to increase-Natural selection-Man the most dominant animal in the world-Importance of his corporeal structure— The causes which have led to his becoming erect-Consequent changes of structure-Decrease in size of the canine teeth-Increased size and altered shape of the skull-Nakedness-Absence of a tail-Defenceless condition of man. It is manifest that man is now subject to much variability. No two individuals of the same race are quite alike. We may compare millions of faces, and each will be distinct. There is an equally great amount of diversity in the proportions and dimensions of the various parts of the body; the length of the legs being one of the most variable points.1 Although in some quarters of the world an elongated skull, and in other quarters a short skull prevails, yet there is great diversity of shape even within the limits of the same race, as with the aborigines of America and South Australia-the latter a race "probably as pure and homogeneous in blood, customs, and language as any "in existence"-and even with the inhabitants of so confined an area as the Sandwich Islands.2 An eminent dentist assures me that there is nearly as much diversity in the teeth as in the features. The chief arteries so frequently run in abnormal courses, that it has been found useful for surgical purposes to calculate from 1040 corpses how often each course prevails. The muscles are eminently variable: thus those of the foot were found by Prof. Turner1 not to be strictly alike in any two out of fifty bodies; and in some the deviations were considerable. 'Investigations in Military and Anthropolog. Statistics of American Soldiers,' by B. A. Gould, 1869, p. 256. وو 2 With respect to the "Cranial forms of the American aborigines,' see Dr. Aitken Meigs in Proc. Acad. Nat. Sci.' Philadelphia, May, 1868. On the Australians, ee Huxley, in Lyell's Antiquity of Man,' 1863, p. 87. On the Sandwich Islanders, Prof. J. Wynan, 'Observations on Crania,' Boston, 1868, p. 18. 3 6 Anatomy of the Arteries,' by R. Quain. Preface, vol. i. 1844. Transact. Royal Soc. Edin burgh,' vol. xxiv. pp. 175, 189. He adds, that the power of performing the appropriate movements must have been modified in accordance with the several deviations. Mr. J. Wood has recorded the occurrence of 295 muscular variations in thirty-six subjects, and in another set of the same number no less than 558 variations, those occurring on both sides of the body being only reckoned as one. In the last set, not one body out of the thirty-six was "found totally wanting in departures from the standard descriptions of the "muscular system given in anatomical text books." A single body presented the extraordinary number of twenty-five distinct abnormalities. The same muscle sometimes varies in many ways: thus Prof. Macalister describes no less than twenty distinct variations in the palmaris accessorius. Но The famous old anatomist, Wolff, insists that the internal viscera are more variable than the external parts: Nulla particula est quæ non aliter et aliter in aliis se habeat hominibus. has even written a treatise on the choice of typical examples of the viscera for representation. A discussion on the beau-ideal of the liver, lungs, kidneys, &c., as of the human face divine, sounds strange in our ears. The variability or diversity of the mental faculties in men of the same race, not to mention the greater differences between the men of distinct races, is so notorious that not a word need here be said. So it is with the lower animals. All who have had charge of menageries admit this fact, and we see it plainly in our dogs and other domestic animals. Brehm especially insists that each individual monkey of those which he kept tame in Africa had its own peculiar disposition and temper: he mentions one baboon remarkable for its high intelligence; and the keepers in the Zoological Gardens pointed out to me a monkey, belonging to the New World division, equally remarkable for intelligence. Rengger, also, insists on the diversity in the various mental characters of the monkeys of the same species which he kept in Paraguay; and this diversity, as he adds, is partly innate, and partly the result of the manner in which they have been treated or educated.8 I have elsewhere so fully discussed the subject of Inheritance, that I need here add hardly anything. A greater number of Proc. Royal Soc.' 1867, p. 544; also 1868, pp. 483, 524. There is a previous paper, 1866, p. 229. Proc. R. Irish Academy,' vel. . 1868, p. 141. Act. Acad. St. Petersburg,' 1778, part i 217 Brehm, Thierleben,' B. 1. s. 38, 87. Rengger, Säugethiere von Paraguay,' s. 57. Variation of Animals and Plants under Domestication,' vol .i. chap. xii. facts have been collected with respect to the transmission of the most trifling, as well as of the most important characters in man, than in any of the lower animals; though the facts are copious enough with respect to the latter. So in regard to mental qualities, their transmission is manifest in our dogs, horses, and other domestic animals. Besides special tastes and habits, general intelligence, courage, bad and good temper, &c., are certainly transmitted. With man we see similar facts in almost every family; and we now know, through the admirable labours of Mr. Galton," that genius which implies a wonderfully complex combination of high faculties, tends to be inherited; and, on the other hand, it is too certain that insanity and deteriorated mental powers likewise run in families. With respect to the causes of variability, we are in all cases very ignorant; but we can see that in man as in the lower animals, they stand in some relation to the conditions to which each species has been exposed, during several generations. Domesticated animals vary more than those in a state of nature; and this is apparently due to the diversified and changing nature of the conditions to which they have been subjected. In this respect the different races of man resemble domesticated animals, and so do the individuals of the same race, when inhabiting a very wide area, like that of America. We see the influence of diversified conditions in the more civilised nations; for the members belonging to different grades of rank, and following different occupations, present a greater range of character than do the members of barbarous nations. But the uniformity of savages has often been exaggerated, and in some cases can hardly be said to exist." It is, nevertheless, an error to speak of man, even if we look only to the conditions to which he has been exposed, as "far more domesticated" than any other animal. Some savage races, such as the Australians, are not exposed to more diversified conditions than are many species which have a wide range. In another and much more important respect, man differs widely from any strictly domesticated animal; for his breeding has never long been controlled, either by methodical or unconscious selection. No race or body of men has been so 10 Hereditary Genius: an Inquiry into its Laws and Consequences,' 1869. Mr. Bates remarks (The Naturalist on the Amazons,' 1863, vol. ii. P. 159), with respect to the Indians of the same South American tribe, no two of them were at all similar in the shape of the head; one "man had an oval visage with fine "features, and another was quite "Mongolian in breadth and pro "minence of cheek, spread of nos "trils, and obliquity of eyes." 12 Blumenbach, Treatises on Anthropolog.' Eng. translat., 1865, p 205. completely subjugated by other men, as that certain individuals should be preserved, and thus unconsciously selected, from somehow excelling in utility to their masters. Nor have certain male and female individuals been intentionally picked out and matched, except in the well-known case of the Prussian grenadiers; and in this case man obeyed, as might have been expected, the law of methodical selection; for it is asserted that many tall men were reared in the villages inhabited by the grenadiers and their tall wives. In Sparta, also, a form of selection was followed, for it was enacted that all children should be examined shortly after birth; the well-formed and vigorous being preserved, the others left to perish.13 If we consider all the races of man as forming a single species, his range is enormous; but some separate races, as the Americans and Polynesians, have very wide ranges. It is a well-known law that widely-ranging species are much more variable than species with restricted ranges; and the variability of man may with more truth be compared with that of widely-ranging species, than with that of domesticated animals. Not only does variability appear to be induced in man and the lower animals by the same general causes, but in both the same parts of the body are affected in a closely analogous manner. This, has been proved in such full detail by Godron and 13 Mitford's History of Greece,' vol. i. p. 282. It appears also from passage in Xenophon's Memorabilia,' B. ii. 4 (to which my attention has been called by the Rev. J. N. Hoare), that it was a well recognised principle with the Greeks, .hat men ought to select their wives with a view to the health and vigour of their children. The Grecian poet, Theognis, who lived 550 B.C., clearly saw how important selection, if carefully applied, would be for the improvement of mankind. He saw, likewise, that wealth often checks the proper action of sexual selection. He thus writes: "With kine and horses, Kurnus! we proceed If then in outward manner, form, and mind, You find us a degraded, motley kind, Wonder no more, my friend! the cause is plain, (The Works of J. Hookham Frere, vol. ii. 1872, p. 334.) |