Essay on the irregularities of the teeth : with special reference to a theory of causation and the principles of prevention and treatment / by J. Sim Wallace.

  • Wallace, J. Sim (James Sim), 1869-1951.
Date:
1904
Catalogue details

Licence: Public Domain Mark

Credit: Essay on the irregularities of the teeth : with special reference to a theory of causation and the principles of prevention and treatment / by J. Sim Wallace. Source: Wellcome Collection.

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    that they are essentially town dwellers, and they more fre- quently fall a prey to the mal-environment. Of course I do not contend that Jews have not any hereditary racial char- acters, but only that what is generally supposed to be their chief one is probably in many cases to a great extent rather the result of their environment. Another example may be mentioned. In certain races the outer canthus of the eye is tilted upwards. From casual ob- servation I believe that this is a characteristic even among well-developed English children. The usual depressed canthus 1s, as a rule, more pronounced in narrow-faced and thin people, and no doubt this feature, which is by no means as merry looking as the raised outer canthus, might seldom exist among us if we had been fed on foods which necessitated mastication and supplied the body with its physiological requisites. Another speculation which seems to offer ground for con- sideration is the effect of the upright posture in bringing about a diminution in size of the jaw. There is a marked difference in the size of the jaws of the higher apes and those of the aboriginal Australians, and yet their food may not be so very different as regards its physical qualities. It seems possible that the drag on the hyoid, produced by the erect position, may largely account for the diminution in size. It should be remembered, too, that the anthropoid apes make very much more use of their arms than any men. Thus the muscles of the trunk and neck are much more fully developed, and prevent any undue drag on the hyoid. The normal re- lations would no doubt be maintained among children if they were allowed or encouraged to play their own little games, frequently involving a more or less horizontal position. This society will not permit, and even though it sacrifices the health of the child it would be considered ridiculous to ad- vocate games which might dirty the knees or wear holes in trousers. It is rather more in keeping with modern civilisa- tion to drill in erect and strained positions or to sit bolt up- right working with books or “behaving.” Still, the day may L