REED WARBLER 



state the position with regard to the theory of sexual selection, 

 for, as I shall presently show, a struggle for territory is not 

 compatible with one part of that theory. 



The theory of sexual selection really contains two 

 distinct propositions; in the one the male is represented as 

 attaining to reproduction by conquering other males, while 

 in the other by directly exciting the pairing impulse of the 

 female. The first of these is the law of battle, to which is 

 attributed the greater strength of the male, the development 

 of the antlers of the stag, or the mane of the lion, since it 

 is only the better equipped males that will conquer, and thus 

 be enabled to reproduce and leave descendants similarly 

 endowed, and differs altogether from the second proposition, 

 which refers to a peaceable process, whereby it is claimed 

 that vocal and instrumental music, plumes, and colours in 

 birds have been developed owing to the fact that the males, 

 which possess a greater development of those characters 

 excite the females in a higher degree, and are thus more 

 likely to attain to reproduction. This second proposition 

 leaves no scope for the law of battle. Inasmuch, therefore, 

 as they ignore or regard as of secondary importance the 

 desperate and frequent struggles in bird life, while at the 

 same time pleading the immense importance of similar 

 struggles amongst the mammals, the advocates of sexual 

 selection are not consistent, for I cannot believe that such 

 battles have, in the one case, decided the question of reproduc- 

 tion, but in the other in no way influenced it. Moreover, they 

 admit that the conflicts at the period of sexual activity are 

 not confined to mammals, but that they occur amongst the 

 lower vertebrates, amongst beetles and crustaceans, amongst 

 some insects, and even amongst some birds. And I therefore 

 submit that, on their own showing, it is highly improbable that 

 this scheme by which the male has attained to reproduction, 

 the standard of efficiency of the species has been maintained, 

 and the position of the species improved in its relation to 

 the struggle for existence — a scheme elsewhere so uniform 



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