CREATION BY EVOLUTION
The so-called wisdom teeth of man under certain conditions partake of the nature of vestigial organs. As is well known, the milk dentition of a child contains in each half of each jaw two incisor or cutting teeth, one canine or eye tooth, and two molars or grinding teeth, making twenty milk teeth in all. When these teeth are shed a permanent tooth takes the place of each milk tooth and in addition three extra teeth appear in each half-jaw. These are the permanent molars, and their presence increases the permanent teeth to thirty-two. The last of these permanent molars at the back of each jaw is known as the wisdom tooth. Ordinarily the wisdom teeth are cut when the person is between twenty and twenty-five years of age, and they get their name from the belief that at that age the person has arrived at years of discernment. Not a few fail to cut these teeth or, in fact, even to form them at all. In such persons the number of teeth is four short of the usual total. Teeth that fail to cut the gums are of course useless and, in fact, like the vermiform appendix, they may be worse than useless, for such imperfect teeth may at times form centers of disturbance that call for surgical treatment.
This occasional reduction in the permanent dentition of man is in a way foreshadowed by what is seen in the monkeys. The new-world monkeys have a permanent dentition composed of a total of thirty-six teeth; the old-world forms, including the gorilla, chimpanzee, and other anthropoid apes, have four fewer permanent teeth and agree in this respect with man. Man appears to be going one step farther and to be reducing his dentition by dropping out another group of four teeth, the wisdom teeth, a step which, if finally taken, would place his permanent dental outfit at twenty-eight instead of thirty-two teeth. In man wisdom teeth that fail
[ 44 ]
