Among other divergences, the boy forms gangs. Girls do not form gangs. They belong to sets, and sets and gangs are quite different institutions. The set is exclusive, undemocratic. It has no organization, leaders, history, and it owns no property. The set snubs its rivals; the gang fights them. The members of a set also snub one another, quarrel, and backbite. There is none of the deep-seated, instinctive loyalty which the members of a gang have for each other. The normal boy may fight his friend; he does not “get mad at” him. All this is only one aspect of the deep-seated difference between “the only two kinds of people there are in the world, men and women.” Barring dolls and the ability to hurl missiles, little girls and little boys, as they emerge from babyhood, are not so very unlike. But somewhere about the age of ten, the little boy begins to undergo a transformation, which in the girl never takes place at all. He begins to develop the gang-forming instinct. He begins to want to do things which he cannot do at all alone; and cannot, moreover, do with any real satisfaction except in conjunction with a special group of his fellows. The once friendly boy becomes shy of adults, so that only the rare man or woman can retain his full confidence. Girls he scorns. His games tend now to be of the coöperative type, in which there is a definitely organized side, with a leader and more or less specialized functions among the players, and where one side wins or loses to the other as a whole. It is no longer each for himself, but each for the team. A girl can be taught to like this kind of game; a boy takes to it like a duck to water. Apparently, then, a boy joins a gang and a girl does not for precisely the same reason that he throws stones while his sister tends lovingly the dolls that are beneath his contempt. Each is doing instinctively, as a child, for play, what grown men and women have been doing these thousand years for work. For obviously the instinctive activities of the boys’ gang are the necessary duties of the savage man. The civilized boy hunts, fishes, fights, builds huts in the woods, stands loyally by his fellows, and treats all outsiders with suspicion or cruelty, and in general lives the life and thinks the thoughts of the savage man. He is, for the moment, a savage; and he instinctively “plays Indians” as the real savage lives them.