422 Hawkins, Sexual Selection and Bird Song. [oct. 



most vigorous and best nourished females, which are the first to 

 breed in the spring. If such females select the more attractive, 

 and at the same time vigorous males, they will rear a larger number 

 of offspring than the retarded females which must pair with the 

 less vigorous and less attractive males. So it will be if the more 

 vigorous males select the more attractive, and at the same time 

 healthy and vigorous females; and this will especially hold good 

 if the male defends the female and aids in providing food for the 

 young. The advantage thus gained by the more vigorous pair 

 in rearing a larger number of offspring, has apparently sufficed to 

 render sexual selection efficient." 



Wallace was the first critic of the sexual selection theory. He 

 admits that the display of gorgeous colors, the antics and songs 

 of the male bird before the female, as fully demonstrated by Darwin 

 but he says, "it by no means follows that slight difference in the 

 shape, pattern, or colors of the ornamental plumes are what lead 

 a female to give the preference to one male over another; still less 

 that all the females of a species, or the great majority of them, 

 over a wide area of country or for many successive generations 

 prefer exactly the same modifications of colors or ornament." 

 Thus he rules out the idea that the female makes a conscious 

 choice of the male most highly colored or who is the best singer. 

 But this does not destroy the idea that there may be an uncon- 

 scious choice. Indeed, Wallace seems to admit this possibility 

 when he says, "As all the evidence goes to show that, so far as 

 female birds exercise any choice, it is of the most ' vigorous, defiant, 

 and mettlesome' males, this form of sexual selection will act in the 

 same direction (as natural selection), and help to carry on the 

 process of plume development to its culmination." If this choice 

 exercised by the female is unconscious rather than conscious, 

 Darwin's theory is not vitally affected. All he is anxious to 

 demonstrate is that the most vigorous bird succeeds in winning 

 the most desirable mate, however the choice may be made, and if 

 he succeeds in this the bird may pass to his offspring his own char- 

 acters which in succeeding generations will become permanent. 



But Wallace goes deeper in his criticism than the mere matter 

 of choice. He attributes the origin of song to natural selection 

 rather than to sexual selection. Darwin begins with sober colors 



