THE TREND OF EVOLUTION 183 



the earth to other living things. Although this has been the 

 history of many dominant species in the past it does not seem 

 probable that it will be the fate of man, for he is able to adapt 

 himself to changed conditions, to modify his environment, and 

 to control his destiny as no other creature that has ever lived 

 on the earth has been able to do. If conditions of life should 

 ever become so adverse that the entire human race should be- 

 come extinct we may probably assume that all other higher 

 animals would also perish. 



It is possible that the entire race may suffer retrogressive 

 evolution and return to a less highly organized condition. 

 Many other types of animals have passed the climax of their 

 evolution and have then declined and their degenerate repre- 

 sentatives still survive. But in these cases other forms better 

 fitted for survival have taken their places and progress has 

 continued in other lines. Intellectual and social evolution has 

 reached a climax in man and it has so greatly increased his 

 control over himself and his environment that it seems scarcely 

 possible that it will universally and permanently decline and be 

 replaced by less adaptable and less efficient characters. 



Perhaps in future ages the progressive evolution of man will 

 continue, somewhere and somehow. If higher species of man 

 evolve in the future it is not unlikely that this will occur, as in 

 the past, in connection with great secular changes, over which 

 man has no control, such as the rising and sinking of conti- 

 nents, the formation of deserts or mountains or oceans, or 

 changes in climate comparable to the glacial and interglacial 

 epochs, during which human evolution made such wonderful 

 progress. 



In the present conditions and tendencies of the human race, 

 in the contest between progressive and retrogressive forces, 

 we see much cause for anxious concern, but thinking on the 

 distant past and the boundless future creates a feeling of de- 

 tachment and of philosophic calm like that of the dwellers on 



