The Making of Species 



males, or those provided with the best weapons, 

 have prevailed under nature, and have led to 

 the improvement of the natural breed or 

 species." 



"With mammals," says Darwin (loc. cit., 

 p. 763), "the male appears to win the female 

 much more through the law of battle than 

 through the display of his charms." 



In the case of birds, however, feminine prefer- 

 ence comes more into play. It is well known 

 that cocks display their charms to the hens at 

 the breeding season, and Darwin believed that 

 the hen selected the most beautiful of her rival 

 suitors. 



"Just as man," he writes (p. 326 of The 

 Descent of Man, new edition, 1901), "can give 

 beauty, according to his standard of taste, to his 

 male poultry, or, more strictly, can modify the 

 beauty originally acquired by the parent species, 

 can give to the Sebright bantam a new and 

 elegant plumage, an erect and peculiar carriage, 

 so it appears that female birds in a state of 

 nature have, by a long selection of the more 

 attractive males, added to their beauty or other 

 attractive qualities." 



Thus the theory of sexual selection is based 

 on three assumptions. Firstly, that there is in 

 all species competition among the males for 

 females with which to mate. Secondly, that 

 this results in either "the law of battle" among 



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