Chap. IV. MANNEK OF DEVELOPMENT. Ill 



now know through the admirable labours of Mr. G-alton 10 

 that genius, which implies a wonderfully complex com- 

 bination 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 the same 

 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 staud in some relation with 

 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 appa- 

 rently due to the diversified and changing nature of 

 their conditions. The different races of man resemble 

 in this respect 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, 

 the members of which belong to different grades of rank 

 and follow different occupations, presenting a greater 

 range of character than the members of barbarous 

 nations. But the uniformity of savages has often been 

 exaggerated, and in some cases can hardly be said 

 to exist. 11 It is nevertheless an error to speak of man, 

 even if we look only to the conditions to which he 

 has been subjected, as " far more domesticated " 12 than 



10 ' Hereditary Genius : an Inquiry into its Laws and Consequences,' 

 1869. 



11 Mr. Bates remarks (' The Naturalist on the Amazons,' 18G3, vol. ii. 

 p. 159 , with respect to the Indians of the same S. 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 prominence of cheek, spread of nostrils, 

 " aud obliquity of eyes." 



12 Blumenbach, ' Treatises on Anthropolog.' Eng. translat., 1865, 

 p. 205. 



