Chap. iv. 
MANNEB OF DEVELOPMENT. 
Ill 
How 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 
ail cases very ignorant ; but we can see that in man as 
in the lower animals, they stand 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 ; aud 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 
°f diversified conditions in the more civilised nations, 
the members of which belong to different grades of rank 
mid 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 ” u than 
10 ‘Hereditary Genius : an Inquiry into its Laws and Consequences,’ 
1869. 
11 Mr. Bates remarks (• The Naturalist on the Amazons,’ 1863, vol. ii. 
J>- 159), with respect to the Indians of the same S. American tribe, 
jno 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, 
ai b(l obliquity of eyes.” 
12 Blumenbach, 1 Treatises on Anthropolog.’ Eng. translate 1865, 
P- 205. 
