216 
THE DESCENT OF MAN. 
Part 1. 
latter agency, for there is good reason to believe that 
some inherited effect is thus produced . 50 
We have seen in our third chapter that the condi- 
tions 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-slaves . 51 
If, however, we look to the races of man, as distri- 
buted over the world, we must infer that their charac- 
teristic 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 ex- 
posed almost naked to a hot, glaring climate. The un- 
clothed 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 
Arabia, and other analogous cases. Dr. Rolle (‘Der Menseh, seine 
Abstammung,’ &c., 1865, s. 99) states, on the authority of Khanikof, 
that the greater number of German families settled in Georgia, have 
acquired in the course of two generations dark hair and eyes. Mr. D. 
Forbes informs me that the Quichuas in the Andes vary greatly in 
colour, according to the position of the valleys inhabited by them. 
51 Harlan, 4 Medical Researches/ p. 532. Quatrefages (‘Unite de 
TEspece Humaine/ 1861, p. 128) has collected much evidence on this 
head. 
