erefore, they are
practically at a standstill and have remained so for thousands of years.
The two cases are parallel ones. We can safely say that the later
development of man took place in other situations and under other
conditions. We may fairly say the same in regard to the ape. Vigorous
influences must have been brought to bear upon the ancestor of man as
the instigating causes of its mental development into man; and similarly
vigorous influences must have been brought to bear upon primitive man to
set in train his mental development into intellectual man. And the
general character of these influences in both cases may readily be
pointed out. An extraordinary development has taken place in the human
intellect within a few thousands, or tens of thousands, of years,
yielding the difference which exists between the cultivated man of
to-day and the debased savage who probably preceded him, and whose
counterpart still exists. This has undoubtedly been due to influences of
the highest potency. If we can show that influences of equal potency
acted upon man's ancestor, we shall have done much toward indicating how
the ape brain may have grown into the brain of man.

In both cases the main agency was in all probability that of conflict.
Both ape and man, as we take it, developed through some form of warfare.
In the former case it was warfare with the animal kingdom; in the latter
it was warfare with the conditions of nature and with hostile man. Each
of these has been potent in its effects, and to each we owe the
completion of a great stage in the evolution of man.

In the tropics, the home of the anthropoid apes of to-day and, probably,
of the animal we have named the man-ape, war between man and nature
scarcely exists. Nature is not hostile to man. There is no occasion for
clothing and little for habitation. Food is abundant for the sparse
populations. Little exertion is called for to sustain life. Mental
stagnation is very likely to supervene. Yet there, as elsewhere,
conflict has had much to do with such mental progress as exists. Mastery
in warfare is due to superior mental resources, which gradually arise
from the exigencies of conflict, and manifest themselves in greater
shrewdness or cunning, superior ability in leadership, better
organization, fuller mutual aid, and the invention of more destructive
weapons and more efficient tools. War acts vigorously on men's minds,
peace acts sluggishly. In the former case man'