2io Evolution and Adaptation 



other hand, with wolves, foxes, and apparently American 

 squirrels, both sexes are occasionally born black. Hence it 

 is quite possible that with some mammals a difference in 

 color between the sexes, especially when this is congenital, 

 may simply be the result, without the aid of selection, of 

 the occurrence of one or more variations, which from the 

 first were sexually limited in their transmission. Neverthe- 

 less it is improbable that the diversified, vivid, and con- 

 trasted colors of certain quadrupeds, for instance, of the 

 above monkeys and. antelopes, can thus be accounted for." 



Finally, the case of man must be considered from the 

 point of view of sexual selection, for Darwin claims that 

 man has acquired a number of his secondary sexual char- 

 acters in this way. For instance, the beard is an excellent 

 case of a secondary sexual character. Darwin's interpretation 

 is that the beard has been retained, or even developed, 

 through the selection by the females of those males that 

 had this outgrowth best developed. Conversely, the absence 

 of hair on the face of the female is supposed by Darwin to 

 have been brought about by men selecting those women 

 having less hair on their faces. The greater intellect, 

 energy, courage, pugnacity, and size of man are the outcome 

 of the competition of the males with each other, since the 

 individual excelling in these qualities will be able to select 

 the most desirable wife, or wives, and it is assumed will, 

 therefore, leave more descendants. The standard of beauty 

 has been kept up by men selecting the most beautiful women 

 in each generation (the fate of the other married women is 

 ignored), and this beauty is supposed to have been transmitted 

 primarily to their daughters, but also to their sons. 



Although all these forms of selection are imagined to be 

 acting in man, either alternately or simultaneously, yet Dar- 

 win recognizes in man a number of checks to the action 

 of sexual selection : amongst savages, the so-called com- 

 munal marriages ; second, infanticide, generally of the young 



