t it is also
true that man through his social life has produced habits that
resemble or are substitutes for primitive instincts. The love of
combat, especially as it is shown in play indicates the presence of
instinctive roots, but it does not show the existence of a definite
instinct of aggression. This play is in part an off-shoot of the
reproductive motive. These fighting plays of children are in part
sexual plays, and we see them clearly in their true light in some of
the higher mammals most closely related to man.

One aspect of the aggressive habit of man has been too much neglected.
It is highly probable that aggression in man has been far more closely
related to the emotion of fear than to any assumed predatory instinct.
It is a question whether the predatory habit of man, ending in
cannibalism and the hunting of animals for food, did not originate in
the time of the long battle man must have had with animals in which
the animals themselves for the most part played the part of
aggressors. It was not for nothing, at any rate, that our animal
ancestors took to the trees, and it is certain that the fear element
in human nature is very strong and very deeply ingrained. We see
throughout animal life fear expressed by aggressive movements, by the
show of anger, as well as by flight. This is seen especially clearly
in the birds. With all their equipment for the defensive strategy of
flight they express fear instinctively by attacking, and this is
apparently not a result merely of the habit of defending the young.
The great carnivora also attack from fear, and seem normally never to
attack such animals as they do not hunt for prey unless they are
frightened. The charge of the rhinoceros and other great ungulates is
probably always a fear reaction. They appear to have no other
aggressive impulses, certainly none connected with the nutritional
motives since they are herbivorous in habit.

The fear motive is probably much deeper in human nature, both in the
lower and the higher social reactions than is commonly supposed, the
concealment of fear being precisely a part of the strategy of defense.
Fear has created more history than it is usually given credit for. The
aggressive motive alone, in all probability, would never have made
history such a story of battles as it has been. Nations usually
attribute more aggressive intentions and motives to their neighbors
than their neighbors possess, and war is certainly often preci