5o THE POPULAR SCIENCE MONTHLY 



the tendency is to preserve the best and strongest features and eliminate 

 the weak and faulty ones. I remember an elaborate article in some 

 magazine, some years ago, which explained the great prevalence of poor 

 teeth in America by saying, that they are caused by our habit of shaving 

 our faces, while the orientals have sore and weak eyes because they 

 shave their heads. The filth in which the latter live was not taken 

 into account, nor the fact that the American women, who do not shave, 

 have as bad teeth as the men. 



A rather ingenious explanation of the marked disproportion between 

 the size of the teeth and that of the jaw in many Americans, as for 

 example, large teeth in small jaws, so that the former are crowded out 

 of position and overlap one another, is that the big teeth are inherited 

 from one parent and the small jaws from the other. This sounds plaus- 

 ible and since no systematic effort has, so far as I know, been made to 

 find out the truth of the matter, it has been tentatively accepted for 

 want of a better explanation of an exceedingly common phenomenon. 



Eecently some good observers, notably Dr. Sim Wallace and Dr. 

 Harry Campbell, of England, have said that the trouble is not hered- 

 itary at all, but begins in each person's babyhood, and that our teeth 

 are poor and irregular and our jaws contracted because we do not exer- 

 cise these parts sufficiently from infancy to manhood; especially from 

 weaning until six years of age, when the permanent teeth begin to 

 erupt. In support of this statement they point out that the first set 

 of teeth is practically never irregular, never overlaps and is very seldom 

 defective. The beautiful lines of a baby's face are not distorted by 

 irregular or protruding teeth, nor sunken by reason of the non-support 

 of sufficiently wide jaws. The teeth of savages, Hottentots and Esqui- 

 maux are almost invariably excellent, and their jaws and tongues are 

 wider and stronger than ours. This has been proved by the measure- 

 ment of thousands of skulls as well as by observations upon the living 

 inhabitants of the tropics and the arctic regions. 



Dr. Campbell also points out that the frequent occurrence of 

 adenoids in young children is caused by feeding them chiefly "pap." 

 He calls this the " pap age." The good old-fashioned plan of chewing 

 sufficiently hard and dry food to properly exercise and develop the jaws 

 and teeth, seems to have been abandoned in our effete civilization. 

 Instead of the honest " johnny cake " (called in the south " corn pone " 

 or " hoe cake ") upon which such sturdy characters as Andrew Jackson 

 and Abraham Lincoln were wont to subsist — and, by the way, the 

 American negro had good teeth and practically escaped tuberculosis so 

 long as he lived upon simple corn bread and bacon and the vegetables 

 and fruits from the plantation. I started to say, however, instead of 

 corn bread and Boston brown bread and rye and " injun " bread, the 

 breads of our grandfathers, which required mastication and insalivation 



