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INFLUENCE OF CIVILIZATION ON DECAY. 219

That the frequency of decay is greater in civilized races than
among savages has also been established by numerous observa-
tions. Mummery's interesting communications are especially
worthy of mention. He found decay among the old Britons of
the dolichocephalous type in 2.94 per cent., among the brachy-
cephalous Britons in 21.87 per cent., among the Anglo-Saxons in
15.78 per cent., among the Romano-Britons in 28.67 per cent.,
and among the ancient Egyptians in 41.66 per cent.
There is no doubt that a deterioration of the teeth accompanies
the progress of civilization. The reasons for this are many. The
mode of life of most unei^^lized races not only conditions a
sound, well-developed body, but the osseous system, of course
including the teeth, shows the same ^-igorous development, and
above all a compact structure. An individual whose youth is
spent in the open air, unrestricted in his bodily freedom, is likely
to posse'ss a body better developed in all its parts than one who
has been brought up in a modern school-room.
The quality of the food also exerts an influence on the teeth
not to be underrated. They form no exception to the rule that
an unused member will be less perfectly developed than one
constantly used.
The pressure brought to bear upon the teeth by mastication
causes a more lively circulation in the periosteum and in the
pulp, thereby inducing an increased deposit of lime-salts or a
more complete calcification. Practical experience also teaches
that children brought up on soft food (lu'oths, paps, etc.) gener-
ally have bad teeth. If a race of human lacings or of animals
were to make no use of their teeth for several generations, we
should expect to find a gradual deterioration of the dental struc-
ture. It is, to say the least, highly probable that the soft qual-
ity of many of our foods, as compared to those of unci^'ilized
races, conditions a soft, porous dental substance, as well as an
imperfect development of the jaw-bone, and a concomitant
crowded position of the teeth.
Then again, the chemical composition of the food is of great
influence upon the origin and extension of caries. Whoever
grants the truth of our proposition,—no caries without acid,—and
recognizes the fermentative processes in the mouth as the chief