SEXUAL SELECTION 97 



such as the spurs of the cock, the antlers of the stag, 

 etc. Although these can be of use also in the life 

 struggle, Darwin classifies them with ornamental 

 characters and attributes to them an equal importance 

 from the view point of sexual selection. 



Here a slight difficulty is encountered : Whenever 

 the males outnumber the females the process of sex- 

 ual selection is easily imagined; none but the fittest 

 or strongest individuals secure females and transmit 

 their fitness to their offspring. Darwin remarks that 

 this is the case with a few mammals, many birds, cer- 

 tain fishes and insects. Polygamy leads to the same 

 results, for if one male takes several females, many 

 males will be prevented from mating. In most spe- 

 cies, however, the number of individuals of both sexes 

 is about even. This is the way, therefore, in which, 

 according to Darwin, sexual selection exerts its in- 

 fluence in order to attain the same results : 



"Thus with migratory birds, the males generally 

 arrive before the females at their breeding place, so 

 that many males are ready to contend for each fe- 

 male. . . . Throughout the great class of in- 

 sects, the males almost always emerge from the pupal 

 state before the other sex." On the other hand, the 

 strongest and most vigorous females are the first to 

 breed, and as the males fight for them, the strongest, 

 and with some species, the best armed, drive away the 

 weaker males and mate with these most vigorous 



