CHAP. X.] SEXUAL SELECTION. 323 



the action of colour on the safety of woodpeckers, and is full 

 of &quot; possibilities &quot; and &quot; doubts :&quot; 



&quot; As in several woodpeckers the head of the male is bright crimeon, 

 whilst that of the female is plain, it occurred to me that this colour 

 might possibly make the female dangerously conspicuous, whenever 

 she put her head out of the hole containing her nest, and consequently 

 that this colour, in accordance with Mr. Wallace s belief, had been 

 eliminated. This view is strengthened by what Malherbe states with 

 respect to Indo/iicus carlotta ; namely, that the young females, like the 

 young males, have some crimson about their heads, but that this colour 

 disappears in the adult female, whilst it is intensified in the adult male. 

 Nevertheless, the following considerations render this view extremely 

 doubtful : the male takes a fair share in incubation, and would be thus 

 far almost equally exposed to danger; both sexes of many species 

 have their heads of an equally bright crimson ; in other species the 

 difference between the sexes in the amount of scarlet is so slight that 

 it can hardly make any appreciable difference in the danger incurred ; 

 and lastly, the colouring of the head in the two sexes often differs 

 slightly in other ways.&quot; vol. ii. p. 174. 



As to the alleged action of sexual selection on our own 

 species two points may be noticed. Mr. Darwin seximi seioc- 

 considers that we owe to it our power of song and man.*&quot;&quot; 1 

 our hairlessness of body, and that also to it is due the for 

 mation and conservation of the various races and varieties of 

 the human species. 



First, as to the absence of hair. This is a character which 

 Mr. Darwin admits cannot be accounted for by &quot; natural 

 selection,&quot; because manifestly not beneficial ; it is therefore 

 attributed to &quot; sexual selection,&quot; incipient man being sup 

 posed to have chosen mates with less and less hairy bodies ; 

 and the possibility of such action is thought by Mr. Darwin 

 to be supported by the fact that certain monkeys have parts 

 of the body naked. Yet it is a fact that the highest apes 

 have not this posterior nakedness, or have it in a much 

 smaller degree. 



As to the races of mankind, Mr. Darwin s theory, indeed, 

 requires the alternation of constancy and caprice to account 

 for the selection first, and subsequently the conservation, of 

 marked varieties. In order that each race may possess and 



Y 2 



