Page:Popular Science Monthly Volume 15.djvu/268

256 has been often abundantly shown. Hence we should naturally expect the denudation to proceed further in her case than in that of man. Especially among savage and naked races we should conclude that hairlessness on the body would be esteemed a beauty; and we find as a matter of fact that most such races have absolutely smooth and glistening skins. But in Europe men often develop hair about the chest and legs, though not upon the back and shoulders, while women seldom or never do so. Here we see that the hair reappears in the less differentiated male sex rather than in the more differentiated females, with whom sexual selection has produced greater effects; while it also reappears only on those parts where the original denudating causes do not exert any influence. Similarly, the smooth-bodied negroes, transported to America, and subjected at once to a change of conditions and to circumstances which would render sexual selection impossible as regards the hairlessness of the body, rapidly redevelop hair upon the chest. For we must remember that sexual selection can only act in this direction while a race remains wholly or mainly naked. Clothing, by concealing the greater part of the skin, necessarily confines the selective process to features, complexion, and figure.

As to the poll, beard, whiskers of certain races, we must believe that they are the result of selective preferences acting upon general tendencies derived from earlier ancestors, and perhaps aided in the first-mentioned instance by natural selection. The comparative definiteness of these hairy patches, as of the callosities in the monkeys, stamps them at once as of sexual origin. The poll is probably derived by us from some of our anthropoid ancestors, as crests of hair frequently appear upon the heads of the quadrumana. But as man gradually became more erect and less forestine, as he took to haunting open plains and living more in the sunlight, the existence of such a natural covering, as a protection from excessive heat and light upon the head, would doubtless prove of advantage to him; and it might, therefore, very possibly be preserved by natural selection. Certainly it is noticeable that this thick mat of hair occurs in the part of his body which the erect position most exposes to the sunlight, and is thus adaptively analogous to the ridge of hair which runs along the spine or top of the back in many quadrupeds, and which is not visible in any quadrumanous animal that I have examined. The beard also bears marks of a quadrumanous origin, as Mr. Darwin has shown; but its varying presence or absence in certain races affords us a good clew to the general course of evolution in this particular. For among the bearded races a fine and flowing beard is universally admired; while among the beardless races stray hairs are carefully eradicated, thus displaying the same aversion to the intermediate or half-hairy state which, as I suppose, has been mainly instrumental in completely denuding the body of man. Certainly it is a fact that while we can admire a European with a full and handsome development of hair