EVOLUTION OF SOCIAL STRUCTURES 593
of reproduction by division in the Protozoa, and this is what I characterize as the protosocial stage in race-development.
But the multiplication of clans through continuous repro- duction in a geometrical progression, coupled with the limits prescribed by the food-supply, results in the wider and wider separation of the clans, until at length certain clans or hordes \\ill have become so far removed from the primary center of dispersion as to lose all connection with it. At the low stage of mental development necessary to such a race of beings scarcely as much as a tradition would ultimately remain of the existence of a primordial group from which all had descended. One clan would keep budding off from another, and moving out farther and farther along lines of least resistance, until a great area of the earth's surface would at last become thus sparsely inhabited by a multitude of clans, each knowing only the few that are located nearest to it. As the dispersion takes place in all direc- tions from the original center, or as nearly so as the configuration of the country and the nature of the food-supply will permit, those migrating in opposite directions become, after a sufficient lapse of time, so widely separated from one another as to constitute wholly distinct peoples. They all have languages, but in time the local variations that they naturally undergo render them to all intents and purposes different languages, at least so much so that if individuals of these long-separated groups should chance to meet, they could not understand one another. It would be the same with their customs, beliefs, and religion. They would have become in all essential respects different races.
We will suppose that in the end a whole continent is thus peopled with these alien hordes and clans, which would now have become innumerable. The process by which this is brought about is what I have called "social differentiation." But it cannot always last. A new process supervenes, and the stage of social differentiation is succeeded by a stage of social integration. The protosocial stage closes, and the metasocial stage comes on. In the protosocial stage the social structure is the simplest possible. The horde or clan is composed altogether of similar elements. The multiplication of such groups can be nothing but a repetition
