618 THE DESCENT OF MAN. 



attractive to the female. !N"o doubt it is to UP a most 

 grotesque notion that the posterior end of the body should 

 be colored for the sake of ornament even more brilliantly 

 than the face; but this is not more strange than that the 

 tails of many birds should be especially decorated. 



AVith mammals we do not at present possess any evidence 

 that the males take pains to display their charms before 

 tue female; and the elaborate manner in which this is per- 

 formed by male birds and other animals is the strongest 

 argument in favor of the belief that the females admire, 

 or are excitscl by, the ornaments and colors displayed 

 before them. There is, however, a striking parallelism 

 between mammals and birds in all their secondary sexual 

 characters, namely, in their weapons for fighting with rival 

 males, in their ornamental appendages and in their colors. 

 In both classes, when the male differs from the female, the 

 young of both sexes almost always resemble each other, and 

 in a large majority of cases resemble the adult female. In 

 both classes the male assumes the characters proper to his 

 sex shortly before the age of reproduction; and if emas- 

 culated at an early period loses them. In both classes the 

 change of color is sometimes seasonal, and the tints of the 

 naked parts sometimes become more vivid during the act of 

 courtship. In both classes the male is almost always more 

 vividly or strongly colored than the female, and is orna- 

 mented with larger crests of hair or feathers, or other 

 such appendages. In a few exceptional cases the female in 

 both classes is more highly ornamented than the male. 

 AVith many mammals, and at least in the case of one bird, 

 the male is more odoriferous than the female. In both 

 classes the voice of the male is more powerful than that of 

 the female. Considering this parallelism, there can be 

 little doubt that the same cause, whatever it may be, has 

 acted on mammals and birds; and the result, as far as 

 ornamental characters are concerned, may be attributed, 

 as it appears to me, to the long-continued preference of the 

 individuals of one sex for certain individuals of the opposite 

 sex, combined with their success in leaving a larger 

 number of offspring to inherit their superior attractions. 



Equal Transmission of Ornamental Characters to Both 

 Sexes. With many birds, ornaments, which analogy leads 

 us to believe were primarily acquired by the males, have 



