70 THE ORIGIN OF SPECIES 



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

 the severest rivalry between the males of many species to attract, 

 by singing, the females. The rock thrush of Guiana, birds of para- 

 dise, and some others, congregate, and successive males display 

 with the most elaborate care, and show off in the best manner, 

 their gorgeous plumage; they likewise perform strange antics be- 

 fore 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 can- 

 not 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 reason to doubt that 

 female birds, by selecting, during thousands of generations, 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 com- 

 parison with the plumage of the young, can partly be explained 

 through the action of sexual selection on variations occurring at 

 different ages, and transmitted to the males alone or to both sexes 

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

 subject. 



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, 

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

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

 cessive 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 peculiarities 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 bird; indeed, had the tuft 

 appeared under domestication it would have been called a mon- 

 strosity. 



ILLUSTRATIONS OF THE ACTION OF NATURAL SELECTION, OR THE 

 SURVIVAL OF THE FITTEST 



In order to make it clear how, as I believe, natural selection 

 acts, I must beg permission to give one or two imaginary illustra- 



