r importance. The
coming on of the Glacial Age made this question one of major importance.
The supply of fruits and vegetable substances was greatly decreased by
the biting chill, and the number of food animals was correspondingly
reduced; while through much of the year the effects of frost drove the
fish from the streams, and cut off effectually this source of food. Man
was brought into a situation in which only the most active exertion of
his powers of thought could preserve him from annihilation.

He now found the exercise of the art of hunting more difficult than ever
before, one that needed a new development of courage, cunning,
alertness, and endurance, the scarcity of animals obliging him to make
long journeys and attack the strongest creatures. Whether or not he
possessed the poisoned arrow, which the Pygmies now find so effective,
cannot be said, but in all probability he was forced to invent new and
more destructive weapons, a necessity that gave fresh exercise to his
powers of invention. So far as our actual knowledge goes, the art of
chipping stones into weapons and implements was not possessed before
this period, and it may have been a result of the severe exigencies of
the situation and the mental stimulation thence resulting. This art is
not possessed by any of the Pygmies, the nearest approach to it being
the splitting of stone by fire and using the splinters as weapons. Very
likely preglacial man was similarly destitute of this art.

Under the severe strain of the glacial conditions the weak and incapable
doubtless succumbed to the cold and deficiency of food; the strong and
capable survived, gained superior powers, devised new weapons and
implements, and became adapted to a new and decidedly adverse situation.
From long depending, in considerable measure, on his physical powers,
man came to trust more fully than before in his mental faculties, the
result being a much greater variation in the size and activity of his
brain than in other portions of his physical structure. While it had
become more difficult to find and capture food animals, he was at the
same time in greater danger from carnivorous beasts, which were forced
by partial starvation to overcome their dread of man. He was thus
obliged to become as alert and ready in defence as he was in attack, to
associate himself more fully with his fellows in his hunting excursions
and his other labors, and to adapt the forms and forces of nature still
mo