Mr. Darwin also thinks that the differences in external appearance between man and the lower animals are, to a certain extent, due to sexual selection. The chief character of the human race which he proposes to account for in this way is the general hairlessness of the body. “No one supposes,” he says, “that the nakedness of the skin is any direct advantage to man; his body therefore cannot have been divested of hair through natural selection.”[1623] It is curious that the hairlessness of man has puzzled so many anthropologists,[1624] as it may very easily be explained by the law of variation. When man had invented the art of making fire, and the idea of covering himself to secure protection from cold had occurred to his mind, hairlessness was no serious disadvantage in the struggle for existence. Hence natural selection ceased to operate in the matter, and a hairless race gradually arose. We find the same principle at work in various other ways. Civilized man does not need such keen vision as savages;[1625] consequently many of us are short-sighted and few Europeans could match a Red Indian in his power of detecting the symptoms of a trail. For the same reason we are generally inferior to savages in the capacity for discriminating odours, and our teeth are apt to be very much less sound and vigorous than theirs. That sexual selection has had _some_ influence on the physical aspect of mankind is probable. Accurate observers in different parts of the world have remarked that personal deformities are very rare in savage races unaffected by European influence.[1626] This chiefly depends upon the fact that deformed individuals seldom survive the hardships of early life, but, as Sir W. Lawrence says, if they do survive, they are prevented by the kind of aversion they inspire from propagating their deformities.[1627] It is not unlikely that the selection of the best representatives of the race contributes to keep the racial type pure. Sexual selection, too, may be the cause why, among savages, the men are so often handsomer than the women—that is, better specimens of their sex and their race;[1628] whilst, in civilized society, the reverse is true. We have seen that savage women have great liberty of disposing of their own hand, and that, at lower stages of civilization, celibacy occurs almost exclusively among the men. Among us, on the contrary, the unmarried women outnumber the unmarried men, and, whilst a man’s ability to marry depends only to a small extent upon his personal appearance, the like may certainly not be said of women. CHAPTER XIII THE LAW OF SIMILARITY