Chap. XVI.] THE YOUNG LIKE BOTH ADULTS. 201 



Before proceeding, I may remark that under the pres- 

 ent and two next classes of cases the facts are so complex, 

 and the conclusions so doubtful, that any one who feels 

 no especial interest in the subject had better pass them 

 over. 



The brilliant or conspicuous colors which characterize 

 many birds in the present class, can rarely or never be of 

 service to them as a i3rotection ; so that they have prob- 

 ably been gained by the males through sexual selection, 

 and then transferred to the females and the young. It is, 

 however, possible that the males may have selected the 

 more attractive females ; and if these transmitted their 

 characters to their offspring of both sexes, the same re- 

 sults would follow as from the selection of the more at- 

 tractive males by the females. But there is some evidence 

 that this contingency has rarely, if ever, occurred in any 

 of those groups of birds in which the sexes are generally 

 alike ; for if even a few of the successive variations had 

 failed to be transmitted to both sexes, the females would 

 have exceeded to a slight degree the males in beauty. 

 Exactly the reverse occurs under nature ; for in almost 

 every large group, in which the sexes generally resemble 

 each other, the males of some few species are in a slight 

 degree more brightly colored than the females. It is 

 again possible that the females may have selected the 

 more beautiful males, these males having reciprocally 

 selected the more beautiful females; but it is doubtful 

 whether this double process of selection would be likely 

 to occur, owing to the greater eagerness of one sex than 

 the other, and whether it would be more elEcient than 

 selection on one side alone. It is, therefore, the most 

 probable view that sexual selection has acted, in the pres- 

 ent class, as far as ornamental characters are concerned, in 

 accordance with the general rule throughout the animal 

 kingdom, that is, on the males; and that these have 



