LIGHT THROWN BY THE EXPERIMENTAL 

 STUDY OF HEREDITY UPON THE FAC- 

 TORS AND METHODS OF EVOLUTION 1 



DR. C. B. DAVENPORT 

 Cold Spring Harbor, N. Y. 



The most important contribution of modern studies in 

 heredity to the topic of evolution has been a neir form il- 

 lation of the problem. Until a decade ago the problem 

 of organic evolution was regarded as synonymous with 

 that of the origin of species. We were, however, not 

 agreed as to the definition of species ; on the contrary, 

 we realized that our notion of the term was exceedingly 

 hazy. And, doubtless, the reason why we made so little 

 progress in getting at the methods of evolution was be- 

 cause of this bad formulation. 



To-day all this is changed. We think less of the origin 

 of species and more of characteristics; of their nature, 

 their origin and their distribution. The concrete ques- 

 tion of the origin of a given species has become broken 

 up into the questions of the origin of its differential 

 characters. Thus, the problem of the origin of man has 

 been broken up into the problems of loss of the tail, of 

 the hairy coat, of skin pigmentation, of melanic iris pig- 

 mentation, the acquisition of a more complicated brain 

 structure, the reduction of the lower part of the face, 

 the acquisition of the ability to learn to count and 

 talk, to wear clothes, to be honest, truthful, regardful <>t 

 the property rights of others, and to exercise self-control 

 in the sex sphere. So long as we formulated our problem 

 as the explanation of the ''origin of the human species," 

 as though the human species were an indivisible unit, so 



1 Bead (with slight alterations) before the American Society o a u- 



