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 iu number ; and as it has ever}" 
where been observed that savages are much opposed to 
any change of habits, by which means injurious checks 
could he 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 Races 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® through the Aryan branches having been 
largely crossed during their wide diffusion by various 
indigenous tribes. When two races in close contact 
3f. .. Or Anthropology,” translation, * Anthropolog. Review,’ J a "' 
186S, p, 38. 
