298 THE DESCENT OF MAN 



habits of animals, this view is hardly probable, for the male 

 is generally eager to pair with any female. It is more prob- 

 able that the ornaments common to both sexes were acquired 

 by one sex, generally the male, and then transmitted to the 

 offspring of both sexes. If, indeed, during a lengthened 

 period the males of any species were greatly to exceed the 

 females in number, and then during another lengthened 

 period, but under different conditions, the reverse were 

 to occur, a double, but not simultaneous, process of sexual 

 selection might easily be carried on, by which the two sexes 

 might be rendered widely different. 



We shall hereafter see that many animals exist of which 

 neither sex is brilliantly colored nor provided with special 

 ornaments, and yet the members of both sexes or of one 

 alone have probably acquired simple colors, such as white 

 or black, through sexual selection. The absence of bright 

 tints or other ornaments may be the result of variations of 

 the right kind never having occurred, or of the animals 

 themselves having preferred plain black or white. Obscure 

 tints have often been developed through natural selection 

 for the sake of protection, and the acquirement through 

 sexual selection of conspicuous colors appears to have been 

 sometimes checked from the danger thus incurred. But in 

 other cases the males during long ages may have struggled 

 together for the possession of the females, and yet no effect 

 will have been produced, unless a larger number of off- 

 spring were left by the more successful males to inherit 

 their superiority, than by the less successful: and this, as 

 previously shown, depends on many complex contingencies. 



Sexual selection acts in a less rigorous manner than natu- 

 ral selection. The latter produces its effects by the life or 

 death at all ages of the more or less successful individuals. 

 Death, indeed, not rarely ensues from the conflicts of rival 

 males. But generally the less successful, male merely fails 

 to obtain a female, or obtains a retarded and less vigoroiis 

 female later in the season, or, if polygamous, obtains fewer 

 females; so that they leave fewer, less vigorous, or no off- 



