2. _War for the possession of limited resources is the first rude social remedy for an excess of population._ War is the normal condition of most primitive tribes. Its cause usually appears to be standing feuds and ancient enmities, but the deeper and abiding cause is the struggle for hunting-grounds, for pasturage, for natural resources. The rude industry and economy of hunting, fishing, or pastoral peoples, or of those in the earlier stages of agriculture, requires a large area for a small population. Distant excursions and frequent forays, when food fails, develop rival claims to favored districts, and war is the only settlement. Fighting under these conditions is an activity of such economic importance that much of the energy of the tribe must be strenuously given to it. The ceaseless loss of life in savage wars is almost incredible to modern minds. The invasion of the Roman Empire by the Teutonic tribes, the later successive inundations of medieval Europe by the fierce pastoral tribes from central Asia, are more recent and familiar examples of the economic and political effects of the increase of population and of the outgrowing of resources by barbarian peoples. When the custom arises of capturing enemies and reducing them to slavery instead of killing them, forces are set into operation to reorganize society and to create new checks on the growth of population. [Sidenote: Crude beginnings of volitional control] 3. _Volitional control of population begins by the destruction of offspring before or after birth._ The population problem ceases to be simply biologic, and takes on its sociological aspect, when the awakening intelligence of man first grasps the mystery of birth, and when the first attempts are made in any way to regulate family relations or to interfere with the growth of numbers. The student of primitive peoples finds in the methods applied to prevent the birth of children an almost inconceivable brutality. The same methods to a large degree persist in savage communities to-day. Infanticide was generally practiced in ancient times among peoples of advanced civilization, as, for example, in Sparta and Rome, where not only deformed and weak children, but unwelcome ones, commonly were destroyed. The practice, if not legalized, is at least permitted even to-day by public opinion in great portions of India, China, and other densely populated districts of the world. It is one of the dark spots on our own civilization. [Sidenote: Private property limits population] [Sidenote: The problem a psychic one]