LAWS CONTROLLING HUMAN SOCIAL HEREDITY 337 



acquired characteristics not only play a part but 

 that they constitute almost the whole social evolu- 

 tion. With this understanding of the development 

 of civilization, it is clear that the problem of explain- 

 ing the evolution of society is not like the problem 

 of the evolution of animals. All attempts made to 

 compare the development of society with the develop- 

 ment of the organism are fundamentally vitiated by 

 these radical differences in the nature of the phe- 

 nomena to be explained. In one case we have the 

 explanation of the gradual modification of the organ- 

 ism through the laws of selection and descent. In 

 the other case we have merely the accumulation of 

 a series of artificial products which heap themselves 

 up age after age, through the process of accretion. 

 The development of society under the force of social 

 heredity is a phenomenon entirely distinct from that 

 of the development of animals under the laws of 

 organic evolution, and they must never be confused 

 with each other. The laws which regulate the one 

 are clearly not the laws that regulate the other. Or- 

 ganic heredity has produced the human animal, 

 but social heredity has produced the modern social 

 man. 



The two different classes of influences which de- 

 termine what any living being shall be have some- 

 times been referred to under the terms "nature" 

 and "nurture," the former referring to that derived 

 by organic inheritance and the latter by social inher- 

 itance. It has been a general result of the last thirty 

 years to emphasize nature and minimize nurture. 

 Perhaps this was natural, since the previous gen- 

 erations had placed more emphasis upon nurture 

 and failed to appreciate nature. Our study of the 



