CHARLES DARWIN 235 



sexual selection, as the mane of the lion, and the hooked jaw to the 

 male salmon; for the shield may be as important for victory as the 

 sword or spear. 



Amongst birds, the contest is often of a more peaceful character. 

 All those who have attended to the subject believe that there is the 

 severest rivalry between the males of many species to attract, by sing- 

 ing, the females. The rock-thrush of Guiana, birds of paradise, and 

 some others, congregate ; and successive males display with the most 

 elaborate care, and show off in the best manner, their gorgeous plum- 

 age; they likewise perform strange antics before the females, which, 

 standing by as spectators, at last choose the most attractive partner. 

 Those who have closely attended to birds in confinement well know 

 that they often take individual preferences and dislikes : thus Sir R. 

 Heron has described how a pied peacock was eminently attractive 

 to all his hen birds. I cannot here enter on the necessary details ; but 

 if man can in a short time give beauty and an elegant carriage to his 

 bantams, according to his standard of beauty, I can see no good rea- 

 son to doubt that female birds, by selecting, during thousands of gen- 

 erations, the most melodious or beautiful males, according to their 

 standard of beauty, might produce a marked effect. Some well- 

 known laws, with respect to the plumage of male and female birds, 

 in comparison with the plumage of the young, can partly be explained 

 through the action of sexual selection on variations occuring at dif- 

 ferent ages, and transmitted to the males alone or to both sexes at 

 corresponding ages ; but I have not space here to enter on this sub- 

 ject. 



Thus it is, as I believe, that when the males and females of any 

 animal have the same general habits of life, but differ in structure, 

 colour, or ornament, such differences have been mainly caused by 

 sexual selection : that is, by individual males having had, in successive 

 generations, some slight advantage over other males, in their weapons, 

 means of defence, or charms, which they have transmitted to their 

 male offspring alone. Yet, I would not wish to attribute all sexual 

 differences to this agency : for we see in our domestic animals peculiar- 

 ities arising and becoming attached to the male sex, which apparently 

 have not been augmented through selection by man. The tuft of 

 hair on the breast of the wild turkey-cock cannot be of any use, and 

 it is doubtful whether it can be ornamental in the eyes of the female 



