Although, in an extreme case, man is able to survive the total loss of the teeth, it cannot yet be said that teeth are useless or harmful. None the less, a study of the human dentition reveals that this set of organs is out of harmony with the fundamental needs of our race. The monkeys of the old world (_Catarrhines_), although they belong obviously to the brute creation, already exhibit a tendency to reduction in the number of teeth. While American monkeys (_Platyrrhines_) may possess thirty-six teeth, the old world forms do not possess more than thirty-two in all, at least as a normal occurrence. Selenka[67] has shown that among gorillas and ourangs individuals with a fourth pair of molars, bringing up the number of teeth to thirty-six, are not rare. He found these additional molars in 20 per cent. of one hundred and ninety-four adult skulls of ourangs. On the other hand, in the cases of the chimpanzee and the gibbon, the third pair of molars differ from the others in smaller size and occasional absence. This reduction is to be associated with the smaller jaws and less powerful mastication of these anthropoids. Cases of supplementary molars are very rare in man, and occur more frequently in the lower races, such as negroes, Australians, and natives of New Caledonia.[68] On the other hand, absence of the third pair of molars, that is to say, of the wisdom teeth, is quite frequent, especially in the white races. Nearly 10 per cent. of Europeans throughout their lives have no more than twenty-eight teeth, the wisdom teeth being absent. This absence is more common in the upper jaw, where it occurs in from 18 to 19 per cent. of men. The loss of the wisdom teeth[69] is on the whole to be regarded as an advantage. Certainly from the “physiological point of view the part played by the wisdom teeth is subordinate. Their power of masticating is feeble; the loss does not appreciably interfere with mastication. The complete absence of all four has no influence on mastication.”[70] These teeth are cut very late, often not appearing until the thirtieth year and sometimes being delayed to extreme old age.