240 THE DESCENT OF MAN. Part I. 



conscious of this parallelism, for he compares his future 

 fate with that of the native rat almost exterminated by 

 the European rat. The difficulty, though great to our 

 imagination, and really great if we wish to ascertain 

 the precise causes, ought not to be so to our reason, 

 as long as we keep steadily in mind that the increase of 

 each species and each race is constantly hindered by 

 various checks ; so that if any new check, or cause of 

 destruction, even a slight one, be superadded, the race 

 will surely decrease in number ; and as it has every- 

 where been observed that savages are much opposed to 

 any change of habits, by which means injurious checks 

 could be counterbalanced, decreasing numbers will 

 sooner or later lead to extinction ; the end, in most 

 cases, being promptly determined by the inroads of 

 increasing and conquering tribes. 



On the Formation of the Baces of Man. — It may be 

 premised that when we find the same race, though 

 broken up into distinct tribes, ranging over a great 

 area, as over America, we may attribute their general 

 resemblance to descent from a common stock. In some 

 cases the crossing of races already distinct has led to 

 the formation of new races. The singular fact that 

 Europeans and Hindoos, who belong to the same Aryan 

 stock and speak a language fundamentally the same, 

 differ widely in appearance, whilst Europeans differ 

 but little from Jews, who belong to the Semitic stock 

 and speak quite another language, has been accounted 

 for by Broca 36 through the Aryan branches having been 

 largely crossed during their wide diffusion by various 

 indigenous tribes. When two races in close contact 



36 " On Anthropology," translation, ' Anthropolog. Eeview,' Jan. 

 1868, p. 38. 



