bly some of the strongest motives that led men to attack
animals also included man as an object, since the alien group was
regarded as in some degree different in kind from the in-group. It
may have been in the great migrations when all the aggressive motives
were increased that cannibalism became fixed as a habit.

Cannibalism may well have been the primitive motive of warfare as
serious deadly combat, but all predatory habits must have contributed
to establishing a more or less habitual state of warfare among all
groups of men. The predatory raid, with the reaction of defense, when
carried on as a group activity in any form, is in fact war, so far as
attack and defense were serious and deadly, and intelligence and
weapons were sufficiently developed to make man a dangerous opponent.
This predatory motive, of course, extended to all desired objects, and
these objects must have included all objects that could most simply be
acquired by stealing. They included food, women, and all other
possessions. The custom of driving out young males from the group, by
the jealousy of the old males, and of preventing males from obtaining
females within the group must have been one of the earliest and one of
the strongest incentives to predatory warfare. At first all property
of the group, for so long as groups were wandering, was to some extent
common, and attack and defense must have been common. The objects of
predatory raids which produced group combat must have changed with the
social life. When habitation became fixed and property therefore more
individual, probably the predatory impulse itself became relatively a
less important factor in combat.

Two motives grow out of the practical motives of combat, which we may
assume to have been the original motives. These are both emotional
rather than instinctive. Fear and anger, that is to say, become more
or less detached motives for attack. Fear is increased with the
increase of intelligence up to a certain point at least--with the
increase of the capacity for understanding danger, and of the powers
of man to become dangerous. All the experience of combat engenders
anger and hatred, and these moods of hatred toward enemies are
cumulative, absorb all the detached motives and feelings of antagonism
between groups, preserve and give continuity to the memories of
conflict, and so produce among groups the fear and hate motive. The
feeling of fear arouses the motive of aggression, and the