792 THE DESCENT OF MAN 



distinct genera. Such strongly marked differences must be 

 in some manner highly important; and we know that they 

 have been acquired in some instances at the cost not only 

 of inconvenience, but of exposure to actual danger. 



The belief in the power of sexual selection rests chiefly 

 on the following considerations: Certain characters are con- 

 fined to one sex; and this alone renders it probable that in 

 most cases they are connected with the act of reproduction. 

 In innumerable instances these characters are fully devel- 

 oped only at maturity, and often during only a part of the 

 year, which is always the breeding season. The males 

 (passing over a few exceptional cases) are the more active 

 in courtship; they are the better armed, and are rendered 

 the more attractive in various ways. It is to be especially 

 observed that the males display their attractions with elabo- 

 rate care in the presence of the females, and that they rarely 

 or never display them excepting during the season of love. 

 It is incredible that all this should be purposeless. Lastly, 

 we have distinct evidence, with some quadrupeds and birds, 

 that the individuals of one sex are capable of feeling a 

 strong antipathy or preference for certain individuals of 

 the other sex. 



Bearing in mind these facts, and the marked results of 

 man's unconscious selection, when applied to domesticated 

 animals and cultivated plants, it seems to me almost certain 

 that if the individuals of one sex were during a long series 

 of generations to prefer pairing with certain individuals of 

 the other sex, characterized in some ■ peculiar manner, the 

 offspring would slowly but surely become modified in this 

 same manner. I have not attempted to conceal that, except- 

 ing when the males are more numerous than the females, 

 or when polygamy prevails, it is doubtful how the more 

 attractive males succeed in leaving a larger number of 

 offspring to inherit their superiority in ornaments or other 

 charms than the less attractive males; but I have shown 

 that this would probably follow from the females — espe- 

 cially the more vigorous ones, which would be the first to 



