Broca to the fine form and capacity of the skulls of Les Eyzies, a race of cave-dwellers undoubtedly contemporary with the reindeer in Southern France.[26] He also argues that the loss, by man, of the hairy covering so long persistent in the mammalia, cannot have taken place on account of its lack of usefulness, since even the most savage tribes show a need of it, endeavoring to replace it by artificial coverings, especially on the back. This naked skin is, however, of importance to civilization, since it leads to the adoption of both clothing and houses, and develops, through the former, the sense of modesty. The loss of the prehensile character of the whole foot, and especially of the pedal thumb, is a preparation for civilization. So, too, the capacity of the human voice for music, of little use to savages, since their singing consists only in a sort of monotonous howling, must be regarded as a preparation for the civilized man's delight in music, and probably also for a higher state than that to which we have yet attained. Nor can the sanctity which attaches to virtue, even among savages, be explained by utility or natural selection. The "mystic sense of wrong," which, although few laws enforce truth, yet attaches to untruth, even among whole tribes of utter savages, is an example of such sanctity. Wallace adds, however, in the same breath: "No very severe reprobation follows untruth. In all ages, falsehood has been thought venial or even laudable under certain conditions." He asserts that "the utilitarian doctrine is not sufficient to account for the development of the moral sense," but seems, nevertheless, to adopt a utilitarian principle as the basis of the moral sense when he says: "Where free play is allowed to the relations between man and man, this feeling [_i.e._ of sanctity] attaches itself to those acts of universal utility or self-sacrifice which are the products of our affections and sympathies which we term moral"; and he adds: "while it may be, and often is, perverted to give the same sanction to acts of narrow and conventional utility which are really immoral,--as when the Hindoo will tell a lie, but will sooner starve than eat unclean food; and looks upon the marriage of adult females as gross immorality." The explanation of this inconsistency is, according to Wallace, that the strength of the moral feeling, in any case, will depend on the individual or racial constitution, and on education and habit; and the acts to which its sanctions are applied will depend on the extent of modification of the simple feelings and affections by custom, law, and religion. If a moral sense is an essential part of our nature, it is easy to see that its sanction may often be given to acts which are useless or immoral, just as the natural appetite for drink is perverted by the drunkard into the means of his destruction.