600 ^tlE DESCENT OF MAN, 



CHAPTER XVIII. 



SECONDARY SEXUAL CHARACTERS OF MAMMALS 



continued. 



Voice Remarkable sexual peculiarities in seals Odor Develop- 

 ment of the hair Color of the hair and skin Anomalous case 

 of the female being more ornamented than the male Color and 

 ornaments due to sexual selection Color acquired for the sake 

 of protection Color, though common to both sexes, often due to 

 sexual selection On the disappearance of spots and stripes in 

 adult quadrupeds On the colors and ornaments of the quad- 

 rumana Summary. 



Quadrupeds use their voices for various purposes, as a 

 signal of danger, as a call from one member of a troop to 

 another, or from the mother to her lost offspring, or from 

 the latter for protection to their mother; but such uses 

 need not here be considered. We are concerned only with 

 the difference between the voices of the sexes; for instance, 

 between that of the lion and lioness, or of the bull and 

 cow. Almost all male animals use their voices much more 

 during the rutting-season than at any other time ; and 

 some, as the giraffe and porcupine,* are said to be com- 

 pletely mute excepting at this season. As the throats {i.e. 

 of the larynx and thyroid bodies f) of stags periodically 

 become enlarged at the beginning of the breeding-season, 

 it might be thought that their powerful voices must be 

 somehow of high importance to them; but this is very 

 doubtful. From information given to me by two experi- 

 enced observers, Mr. McNeill and Sir P. Egerton, it seems 

 that young stags under three years old do not roar or 

 bellow; and that the old ones begin bellowing at the com- 

 mencement of the breeding-season, at first only occasionally 

 and moderately, while they restlessly wander about in 

 search of the females. Their battles are prefaced by loud 



*Owen, " Anatomy of Vertebrates," vol. iii, p. 585. 

 t Ibid, p. 595. 



