HUMAN AND ANIMAL EVOLUTION CONTRASTED 9 



cannot, from the standpoints of its results, be com- 

 pared with that of any other animal. It may well, 

 therefore, be possible that his evolution may have 

 been brought about by new forces and controlled by 

 new laws, so that the conclusions drawn from the 

 study of animals may not be legitimate, or at least 

 not adequate, when applied to man. 



The organic evolution of animals and plants in 

 general has been brought about by the action of 

 three great factors, namely, reproduction, variation, 

 and heredity. It has been the task of the last half 

 century to work out the laws by which these factors 

 have brought about the history of the living world 

 which we have called organic evolution. It was 

 Darwin who first set us thinking about this subject. 

 In the years that have passed since Dai-win, new 

 data have forced upon us a considerable modifica- 

 tion of the views advanced first by him. These years 

 have disclosed many details of the method of action 

 of these forces in producing evolution, and while 

 to-day we cannot pretend that we understand the 

 process fully, we certainly have an approximate idea 

 as to how these three forces have interacted with 

 each other to produce the living world of to-day. In 

 applying these principles to man it has been as- 

 sumed that the laws discovered for animals apply 

 also to man. Unquestionably they do up to a cer- 

 tain point. But since the human race is more than 

 a simple animal, it is possible that its unique attri- 

 butes may have been developed under a different set 

 of forces. 



Heredity. — Whatever may have been the details of 

 the method by which organic evolution has been 

 brought about, there is no question that the primary 



