MANNER OF DEVELOPMENT. 55 



and otters. Elephants and rhinoceroses 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 ap- 

 pear as if the existing species of hoth 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" than those on the lowlands. May 

 we then infer that man became divested of hair from having abor- 

 iginally 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, favors this in- 

 ference — on the assumption that the hair was lost before man be- 

 came 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,'* is opposed to the supposition that man be- 

 came naked through the action of the sun. Mr. Belt believes™ 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 

 suflScient 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, ac- 

 quired any specialized means of relief. The view which seems to 

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

 became divested of hair for ornamental purposes, as we shall see 

 under Sexual Selection; and, according to this belief, it is not sur- 

 prising that man should differ so greatly in hairiness from aU 



^ Owen, 'Anatomy of Vertebrates,' vol. iii. p, 619. 



88 Isidore Geoffrey St.-HIlaire remarks ('Hist. Nat. Generale,' torn, 

 ii. 1859, pp. 215-217) on the head of man being covered with long hair; 

 also on the upper surfaces of monlceys and of other mammals being 

 more thickly clothed than the lower surfaces. This has likewise been 

 observed by various authors. Prof. P. Gervais ('Hist. Nat. des Mam- 

 miferes,' tom. i. 1854, p. 28), however, states that in the Gorilla the hair 

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

 lower surface. 



*» The 'Naturalist in Nicaragua,' 1874, p. 209. As some confirmation of 

 Mr. Belt's view, I may quote the following passage from Sir "W. Deni- 

 son ('Varieties of Vice-Regal Life' vol. i. 1870, p. 440): "It is said to be 

 "a practice with the Australians, when the vermin get troublesome, 

 "to singe themselves." 



