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Show 2-16 THE DESCENT OF MAN. PART I. latter agency, for there is good reason to believe that some inherited effect is thus produced.60 ·vv e have seen in our third chapter that the conditions of life, such as abundant food and general comfort, affect in a direct manner the development of the bodily frame, the effects being transmitted. Through the combined influences of climate and changed habits of life, European settlers in the United States undergo, as is generally admitted, a slight but extraordinarily rapid change of appearance. There is, also, a considerable body of evidence shewing that in the Southern States the house-slaves of the third generation present a markedly different appearance from the :field-slavesY If, however, we look to the races of man, as distributed over the world, we must infer that their characteristic differences cannot be accounted for by the direct action of different conditions of life, even after exposure to them for an enormous period of time. The Esquimaux live exclusively on animal food; they are clothed in thick fur, and are exposed to intense cold and to prolonged darkness ; yet they do not differ in any extreme degree from the inhabitants of Southern China, who live entirely on vegetable food and are exposed almost naked to a hot, glaring climate. 1'he unclothed Fuegians live on the marine productions of their inhospitable shores ; the Botocudos of Brazil wander 50 See, for instance, Quatrefages ('Revue des Cours Scientifiques,' Oct. _10, 1868, p. 724) on the effects of residence in Abyssinia and Arabut, and other analogous cases. Dr. Rolle (' Der Mensch, seine Abstammung,' &c., 18G5, s. 99) states, on the authority of Khanikof, that the greater number of German families settled in GeorO'ia have acquire~ in the course of two generations dark hair and eyes."' Mr. D. Forbes mfor~s me that t~e. Quichuas in tho Andes vary greatly in oolour, accordmg to the posltwn of the valleys inhabited by them. , 51 !farlan, '~e~ical Researches,' p. 532. Quatrefages ('Unite de 1 Espcce Humame, 1861, p. 128) has collected much evidence on tllis hen d. ICU.AP. VII. THE RACES OF MAN~ 247 about the hot forests of the interior and live chiefly on vegetable productions; yet these tribes resemble each other so closely that the Fuegians on board the "Beagle" were mistaken by some Brazilians for Botocudos. 'fhe Botocudos again, as well as the other inhabitants of tropical America, are wholly different from the N~groes who inhabit the opposite shores of the AtlantiC, are ~xposed to a nearly similar climate, and follow nearly the same habits of life. Nor can the differences between the races of man be accounted for, except to a quite insignificant degree, by the inherited effects of the increased or decreased use of parts. Men who habitually live in canoes, may have their legs somewhat stunted; those who inhabit lofty reaions have their chests enlarged; and those who con- o . . • stantly use certain sense-organs have the cav1tles m which they are lodged somewhat increased in size, and their features consequently a little modified. With ·civilised nations, the reduced size of the jaws from lessened use, the habitual play of different muscles serving to express different emotions, and the increased :Size of the brain from greater intellectual activity, hav:e together produced a considerable effect on their general appearance in comparison with savages.52 It is also possible that increased bodily stature, with no corresponding increase in the size of the brain, may have ,given to some races (judging from the previously adduced cases of the rabbits) an elongated skull of the dolichocephalic type. Lastly, the little-understood principle of correlation will almost certainly have come into action, as in the case of great muscular development and strongly pro- 52 See Prof. Schaaffhausen, translat. in 'Anthropological Review., .Oct. 1868, p. 429. |