144 THE DESCENT OF MAN. [Part I. 



clined to believe, as we shall see under sexual selection, 

 that man, or rather primarily woman, became divested of 

 hair for ornamental purposes ; and according to this belief 

 it is not surprising that man should differ so greatly in 

 hairiness from all his lower brethren, for characters gained 

 through sexual selection often differ in closely-related 

 forms to an extraordinary degree. 



According to a popular impression, the absence of a 

 tail is eminently distinctive of man ; but as those apes 

 which come nearest to man are destitute of this organ, 

 its disappearance does not especially concern us. Never- 

 theless it may be well to own that no explanation, as far 

 as I am aware, has ever been given of the loss of the tail 

 by certain apes and man. Its loss, however, is not sur- 

 prising, for it sometimes differs remarkably in length in 

 species of the same genera: thus in some species of Maca- 

 cus the tail is longer than the whole body, consisting of 

 twenty-four vertebrae ; in others it consists of a scarcely- 

 visible stump, containing only three or four vertebra?. In 

 some kinds of baboons there are twenty-five, while in the 

 mandrill there are ten very small stunted caudal vertebra?, 

 or, according to Cuvier, 79 sometimes only five. This great 

 diversity in the structure and length of the tail in animals 

 belonging to the same genera, and following nearly the 

 same habits of life, renders it probable that the tail is not 

 of much importance to them ; and if so, we might have ex- 

 pected that it would sometimes have become more or less 

 rudimentary, in accordance with what we incessantly see 



served by various authors. Prof. P. Gervais ('Hist. Nat. des Mammi- 

 fcres,' torn. i. 1854, p. 28), however, states that in the Gorilla the hair ia 

 thinner on the back, where it is partly rubbed off, than on the lower sur- 

 face. 



19 Mr. St. George Mivart, ' Proc. Zoolog. Soc.' 1805, pp*. 562, 583. Dr. 

 J. E. Gray, ' Cat. Brit. Mus. : Skeletons.' Owen, ' Anatomy of Verte- 

 brates,' vol. ii. p. 517. Isidore Geoffroy, ' Hist. Nat. Gen.' torn. ii. p. 244. 



