21 8 THE DESCENT OF MAN. 



interesting circumstance that the ch;ef check to wild ani- 

 mals becoming domesticated, which implies the power of 

 their breeding freely when first captured, and one chief 

 check to wild men, when brought into contact with civil- 

 ization, surviving to form a civilized race, is the same, 

 namely, sterility from changed conditions of life. 



Finally, although the gradual decrease and ultimate 

 extinction of the races of man is a highly complex 

 problem, depending on many causes which differ in 

 different places and at different times ; it is the same 

 problem as that presented by the extinction of one of 

 the higher animals of the fossil horse, for instance, which 

 disappeared from South America, soon afterward to be 

 replaced, within the same districts, by countless troups of 

 the Spanish horse. The New Zealander seems conscious of 

 this parallelism, for he compares his future fate with that 

 of the native rat now almost exterminated by the Euro- 

 pean rat. Though the difficulty is great to our imagi- 

 nation, and really great, if we wish to ascertain the precise 

 causes and their manner of action, it 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 checked 

 in various ways; so that if any new check, even a slight 

 one, be superadded, the race will surely decrease in number; 

 and decreasing numbers will sooner or later lead to extinc- 

 tion; the end, in most cases, being promptly determined 

 by the inroads of conquering tribes. 



On the Formation of the Races of Man. In some cases 

 the crossing of distinct races has led to the formation of a 

 new race. The singular fact that the Europeans and Hin- 

 doos, who belong to the same Aryan stock and speak 'a 

 language fundamentally the same, differ widely in appear- 

 ance, while Europeans differ but little from Jews, who 

 belong to the Semitic stock and speak quite another lan- 

 guage, has been accounted for by Broca,* through certain 

 Aryan branches having been largely crossed by indigenous 

 tribes during their wide diffusion. AVhen two races in 

 close contact cross the first result is a heterogeneous mix- 

 ture; thus Mr. Hunter, in describing the San tali or hill- 



*" On Anthropology," translation " Antliropolog. Review," Jan., 

 1868, p. 88. 



