Chap. II. Manner of Development. 57 



through the water ; nor would it be injurious to them from the 

 loss of warmth, as the species, which inhabit the colder regions, 

 are protected by a thick layer of blubber, serving the same 

 purpose as the fur of seals and otters. Elephants and rhino- 

 ceroses are almost hairless ; and as certain extinct species, 

 which formerly lived under an Arctic climate, were covered with 

 long wool or hair, it would almost appear as if the existing 

 species of both genera had lost their hairy covering from exposure 

 to heat. This appears the more probable, as the elephants in 

 India which live on elevated and cool districts are more hairy 87 

 than those on the lowlands. May we then infer that man 

 became divested of hair from having aboriginally inhabited some 

 tropical land ? That the hair is chiefly retained in the male sex on 

 the chest and face, and in both sexes at the junction of all four 

 limbs with the trunk, favours this inference — on the assumption 

 that the hair was lost before man became erect ; for the parts 

 which now retain most hair would then have been most protected 

 from the heat of the sun. The crown of the head, however, 

 offers a curious exception, for at all times it must have been one 

 of the most exposed parts, yet it is thickly clothed with hair. 

 The fact, however, that the other members of the order of 

 Primates, to which man belongs, although inhabiting various hot 

 regions, are well clothed with hair, generally thickest on the upper 

 surface, 88 is opposed to the supposition that man became naked 

 through the action of the sun. Mr. Belt believes 89 that within 

 the tropics it is an advantage to man to be destitute of hair, as 

 he is thus enabled to free himself of the multitude of ticks (acari) 

 and other parasites, with which he is often infested, and which 

 sometimes cause ulceration. But whether this evil is of sufficient 

 magnitude to have led to the denudation of his body through 

 natural selection, may be doubted, since none of the many 

 quadrupeds inhabiting the tropics have, as far as I know, 

 acquired any specialised means of relief. The view which seems 

 to me the most probable is that man, or rather primarily woman, 



87 Owen, 'Anatomy of Verte- ever, states that in the Gorilla the 

 brates,' vol. iii. p. 619. hair is thinner on the back, where 



88 Isidore Geoffroy St.-Hilaire re- it is partly rubbed off, than on the 

 marks (' Hist. Nat. Generale,' torn. lower surface. 



ii. 1859, pp. 215-217) on the head of 89 The ' Naturalist in Nicaragua,' 



man being covered with long hair; 1874, p. 209. As some contirma- 



also on the upper surfaces of mon- tion of Mr. Belt's view, I may quote 



keys and of other mammals being the following passage from Sir W. 



more thickly clothed than the lower Demson ('Varieties of Vice-Regal 



surfaces. This has likewise been Life,' vol. i. 1870, p. 440): "It is said 



observed by various authors. Prof. " to be a practice with the Aus- 



P. Gervais (' Hist. Nat. des Mam- " tralians, when the vermin gel 



miferes,' torn. i. 1854, p. 28), how- " troublesome, to singe themselves* ' 



4 



