The Descent of Man

to these animals "a truly frightful physiognomy."
Therefore, as the jaws and teeth in
man's progenitors gradually become reduced in
size, the adult skull would have come to resemble
more and more that of existing man. As
we shall hereafter see, a great reduction of the
canine teeth in the males would almost certainly
affect the teeth of the females through
inheritance.
As the various mental faculties gradually developed
themselves the brain would almost
certainly become larger. No one, I presume,
doubts that the large proportion which the size
of man's brain bears to his body, compared to
the same proportion in the gorilla or orang, is
closely connected with his higher mental powers.
We meet with closely analogous facts with
insects, for in ants the cerebral ganglia are of
extraordinary dimensions, and in all the Hymenoptera
these ganglia are many times larger
than in the less intelligent orders, such as bee-