SEXUAL SELECTION. 221 



powerful and pugnacious than the cocks; these characters being 

 transmitted to the female offspring alone. 



It may be suggested that in some cases a double. process of se- 

 lection has been carried on; that the males have selected the 

 more attractive females, and the latter the more attractive males. 

 This process, however, though it might lead to the modification of 

 both sexes, would not make the one sex different from the other, 

 unless indeed their tastes for the beautiful differed; but this is a 

 supposition too improbable to be worth considering in the case of 

 any animal, excepting man. There are, however, many animals 

 in which the sexes resemble each other, both being furnished with 

 the same ornaments, which analogy would lead us to attribute to 

 the agency of sexual selection. In such cases it may be suggested 

 with more plausibility, that there has been a double or mutual 

 process of sexual selection; the more vigorous and precocious fe- 

 males selecting the more attractive and vigorous males, the latter 

 rejecting all except the more attractive females. But from what 

 we know of the habits of animals, this view is hardly probable, 

 for the male is generally eager to pair with any female. It is 

 more probable 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 or provided with special ornaments, and 

 yet the members of both sexes or of one alone have probably ac- 

 quired simple colors, such as white or black, through sexual selec- 

 tion. 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 pos- 

 session of the females, and yet no effect will have been produced, 

 unless a larger number of offspring were left by the more success- 

 ful males to inherit their superiority, than by the less successful; 

 and this, as previously shown, depends on many complex contin- 

 gencies. 



Sexual selection acts in a less rigorous manner than natural se- 

 lection. The latter produces its effects by the life or death at all 

 ages of the more or less successful individuals. Death, Indeed, 



