26 



NATURAL HISTORY OF VERTEBRATE ANIMALS 



Adaptation in the Human Species. — The case of man appears 

 to be somewhat different from that of the rest of the animal world. 

 While it appears that animals must become adapted to their 

 environment, must change with the changing demands of exist- 

 ence, or perish, man has succeeded to a surprising extent in alter- 

 ing his environment instead of becoming himself modij&ed by 

 the forces of nature. The beaver that builds a dam and constructs 



Fig. 12. — American, beaver and "house." A beaver pond in background with 



dam to left. 



(Photo, by courtesy of the American Museum of Natural History.) 



its "lodge" by felling trees and cutting them in pieces (Fig. 12), 

 or the colony of bees with its nest, alters the environment to suit 

 its needs; but even these extreme cases show relatively little 

 control of the environment when compared with that secured by 

 mankind, unless one accepts a view of the purposeful actions cf 

 animals with which many biologists are not in agreement. Civil- 

 ized man has created for himself conditions that may be charac- 

 terized as " artificial " in contrast with those of nature. He does 

 this by virtue of his intelligence, by understanding nature and by 

 modifying natural conditions to suit his needs. By contrast, other 

 animals must conform to changes in environment or perish. 

 Having persisted in his present manner of life, man cannot return 



