SEXUAL SELECTION 403 



DARWIN" AND WALLACE ON SEXUAL SELECTION AND 

 WARNING COLORATION 



By Professor F. H. PIKE 



COLUMBIA UNIVERSITY 



~T~N looking over the life of Wallace recently, my attention was again 

 -*- drawn to the differences in opinion existing between Darwin and 

 himself, with reference to sexual selection. Wallace objected to Darwin's 

 assumption that a bright or peculiar color or a peculiar note or call 

 would attract the attention of other individuals of the same species but 

 of the opposite sex, on the ground that such a process could not become 

 operative in forms which did not have sufficient intelligence to discrim- 

 inate, and hence could not explain the occurrence of such characters 

 in the lower forms. And if the plaint of the eugenists be accepted at 

 its face value, the degree of intelligence even in the human subject 

 to-day is not sufficient to insure discrimination in choosing a mate. 



The development of our knowledge of animal behavior, on the one 

 hand, and the advances in our knowledge of the nervous system, on the 

 other, appear to me to make possible a reconsideration of the matter 

 from the point of view of one or the other of these two lines of work 

 at the present time. It must not be supposed that the approach from 

 this angle will settle the question quite independently of other con- 

 siderations, but such a method of approach may adduce some independ- 

 ent probability of the soundness or unsoundness of Darwin's point of 

 view. 



In the first place, sexual selection with reference to color of coat or 

 plumage or of song is dependent upon the existence of a particular group 

 of sense organs capable of perceiving objects at a distance — the distance 

 receptors as Sherrington 1 calls them. These are the eye and the ear and 

 the olfactory organ. The perception of color and voice depends there- 

 fore upon the development of the eye and the ear. Sexual selection 

 with reference to these two characters can not be operative, therefore, 

 in forms not able to see or hear. 



It is evident that any other process of selection that is dependent 

 upon coloration, even including protective coloration under certain con- 

 ditions, must be considered from the same point of view. We may, 

 therefore, discuss the subjects of colors of flowers as a means of attract- 

 ing bees, warning coloration, protection by mimicry, and certain phases 



1 Sherrington, "Integrative Action of the Nervous System," New York, 

 1906. 



