i68 WHAT EVOLUTION IS 



in the arrival of a new disease. The 

 first coming of Europeans to America 

 is said to have brought to the native 

 Indian a variety of entirely novel mal- 

 adies. Among these was smallpox. 

 This disease is said to have run like 

 wildfire among the natives and to have 

 reduced their numbers to an almost 

 incredible level. Measles is another 

 disorder of the same kind. To the 

 Aleut Indians, of the extreme North- 

 west, this is a disease of great severity 

 and has been known to have exter- 

 minated whole villages. Yet to Eu- 

 ropeans it is a mere bagatelle due 

 doubtless to the long exposure of this 

 race to it and to the partial immu- 

 nity acquired in the course of time 

 through selection. 



The social habits of man have not 

 only had their influence on the kinds 

 of inheritance that he has developed, 

 but they have impressed his nature 



