to what
extent the small groups of men we find in conditions of savagery now
represent primitive conditions. Fortunately, however, some of these
problems of origin are of but little practical importance and their
interest is chiefly antiquarian or historical.

The assumption that in the behavior of original groups of men war
arose as a natural result of the life of the group seems to be an
allowable hypothesis. Whether warlike conduct came by some
modification of the habits brought up from animal life as instinctive
reactions, or whether man invented warfare from some strong motive
peculiar to human life, and produced it intelligently, so to speak,
under stress of circumstances may have to remain an open question so
far as conclusive evidence is concerned. What we lack is a knowledge
of the type and form of the instincts of man in his first stages, and
the degree and kind of intelligence he had. But the reconstructed
pre-human history of man so far as we can make it seems to show, as we
have already suggested, that early man could have had no definite herd
instincts or pack instincts such as some of the animals have, that his
habits were plastic and guided by intelligence rather than by impulse.
His social life, his predaceous habits, the habit of killing large
game, his warfare must have been a gradual acquisition, and from the
beginning have been very different as regards motive and development
from animal behavior which judged externally may seem to be like it in
character and to have the same ends.

There are already inherent in any group of human individuals that fits
into such knowledge of man past and present as we have, all the
necessary motives of warfare in some form. There are the reactions of
anger made to any threat or injury, fear, the predaceous impulse and
habit, originating in hunger, the motives arising in sexual rivalry.
These motives are the source of behavior toward both members of the
group and outsiders. There is no absolute distinction between these
objects. It is of the nature of man to be both aggressive and social.
One instinct or motive did not come from the other, since there are
emotions and desires at every stage that tend, some of them to unite
and some to disrupt, the group. The sense of difference of kind and
the fear of the strange on the one hand, and the effect of propinquity
and practical necessity in the conduct in regard to the familiar on
the other make the reactions different