ADVANCE OF ANTHROPOLOGY. 495 



might arise a heightened sociality rich in progressive 

 influence. 



(e) With the development of tool-using and sen- 

 tence-making, with the gaining of firmer foothold in 

 nature, with the occasional emergence of the genius, 

 there might arise in permanent products, in sym- 

 bols, in traditions an external heritage, which, it 

 appears to us, has been the most potent factor in se- 

 curing and furthering human progress. For man is 

 relatively a slowly reproducing, slowly varying or- 

 ganism. 



We have not expanded these suggestions, for mere 

 may-be's have no place in science, and a further 

 elucidation of the factors in the evolution of man 

 must be one of the tasks of the twentieth century. 



