64 THE DESCENT OF MAtf. 



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 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 * 

 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, favors 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 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 supposi- 

 tion that man became naked through the action of the sun. 

 Mr. Belt believes that within the tropics it is an advant- 

 age 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 some- 

 times cause ulceration. But whether this evil is of suffi- 

 cient 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 



*0wen, "Anatomy of Vertebrates," vol. iii, p. 619. 



f Isidore Geoffroy 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 monkeys and of other mammals 

 being more thickly clothed than the lower surfaces. This has like- 

 wise been observed by various authors. Prof. P. Gervais (" Hist. 

 Nat. des Mammiferes," torn, 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 confirma- 

 tion of Mr. Belt's view, I may quote the following passage from Sir 

 W. Denison ("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." 



