462 THE ANTIQUITY OF MAN 
" overlapping " bite. In England, during the Anglo- 
Saxon period, the incisor teeth met edge to edge in the 
majority of the inhabitants ; the overlapping bite was 
exceptional. The edge-to-edge incisor bite occurs in all 
primitive human races ; it is also the simian form. In a 
thousand years or less, then, a very remarkable change has 
appeared in the bite of English people ; the overlapping 
incisor bite has become the prevalent form. With the 
change has come a marked tendency to contraction of the 
palate and to irregularities in the arrangement of the teeth. 
At first sight it seems as if a marked evolutionary change 
had been wrought on our teeth and jaws in the course of 
twenty or thirty generations. The changes in our teeth 
and jaws are of a functional nature ; they are comparable 
to certain alterations produced in our feet by the use of 
modern boots and shoes. Were we to abandon boots 
and walk barefooted, as has been the habit in all primitive 
human races, our feet, we believe, would resume their 
natural form. We have every reason to suppose that 
the changes in our mouths are of a similar nature. If 
we had to return to the " hard " fare of our early ancestors 
we should have to use our front teeth in a different manner 
and restore the edge-to-edge bite. 
The manner in which the edge-to-edge incisor bite 
is produced has a very direct bearing on the problems 
relating to changes in man's front teeth. It will be found 
that there is a double mechanism at work during mastica- 
tion. One of these has to do chiefly with the front teeth — 
the biting mechanism ; the other with the back or molar 
teeth — the grinding mechanism. How different these 
mechanisms are the reader may prove by personal 
observation. The great temporal muscle can be felt at 
work on the side of the head, anywhere between the 
ear and lateral margin of the forehead. If ordinary 
chewing movements are made, those which grind the 
lower molar teeth against the upper and force the condyle 
of the lower jaw into the depth of its socket in front of 
the ear-passage, the temporal muscle will be felt to be 
strongly at work ; it swells and subsides at each phase of 
