46 COLOR AND SEX. 



In explanation of these remarkable differences of form 

 and habit, we have first Darwin's theory of " sexual se- 

 lection." This is based upon the ardor in love, the cour- 

 age and rivalry of the males, and also upon the powers 

 of perception, taste, and will of the female. 



The spurs of the male, for example, are supposed 

 to have been developed through the battles of the males. 

 At first a mere knob, they were an advantage to the bird 

 possessing them, enabling him to defeat his rivals. The 

 successful male would be more likely to have offspring 

 who would inherit the tendency of their father to have 

 spurs, and thus, by selection, the unspurred cocks would 

 gradually be replaced by those better armed. This is 

 known as the " law of battle." 



But the bright colors and gay plumes of the cock 

 have originated, under this theory, through the taste of 

 the female, who, it is assumed, would be more likely to 

 accept the attentions of a bird pleasing in her eye than 

 one who was less strikingly adorned. This has been 

 termed by Lloyd Morgan " preferential mating." 



Wallace has accepted the law of battle as an effective 

 agent in producing certain characters, but considers it 

 natural, rather than sexual selection, and he denies the 

 existence of any important evidence proving female selec- 

 tion. He therefore attributes many secondary sexual 

 characters to a surplus of vital energy, which, because of 

 a bird's perfect adaptation to the conditions of its exist- 

 ence, can expend itself in the production of bright colors 

 and ornamental plumes without injury to their owners. 

 That is to say, Wallace ascribes to the action of natural 

 selection any secondary sexual character which is of prac- 

 tical use to the male in conflicts with a rival, but denies 

 the female any part in the matter of pairing. Darwin, 

 as I have said, attributes to the female an aesthetic 

 taste which renders the brilliant colors or display of the 



