The animals have a spontaneous movement of self-defense. Even when they attack for their defense, such a movement implies a retreat in themselves under the form of a curvature of their body.
A human being curves its body, too, when it is threatened by a physical aggression. The backbone takes a bent form; the head bows; the hands are withdrawn near the body; the legs lose the vertical position.
But the most frequent threats of human beings in actual societies have a psychological nature. And the modern societies do not admit the retreat in yourself as a means of self-defense.
It is generally agreed that a successful self-defense of a threatened person should be supported by objective facts. The threatened person must demonstrate her possible psychological injury by presenting objective data in her defense. Any demonstration means to explain yourself to others. You should deliver yourself to them and, thus, you are far away from the natural self-defense as a retreat.
There are at least two consequences: the lack of a natural self-defense makes the human beings more vulnerable to psychological aggressions, because nobody can defend you better than yourself; the aggressive retorts used as means of self-defense are not limited by the movement of retreating in yourself and they become harsher than they naturally should be.