[Sidenote: Small geographic base of primitive societies.]

Growth has been the law of human societies since the birth of man's
gregarious instinct. It has manifested itself in the formation of ever
larger social groups, appropriating ever larger areas. It has registered
itself geographically in the protrusion of ethnic boundaries,
economically in more intensive utilization of the land, socially in
increasing density of population, and politically in the formation of
ever larger national territorial aggregates. The lowest stages of
culture reveal small tribes, growing very slowly or at times not at all,
disseminated over areas small in themselves but large for the number of
their inhabitants, hence sparsely populated. The size of these primitive
holdings depends upon the natural food supply yielded by the region.
They assume wide dimensions but support groups of only a few families on
the chill rocky coasts of Tierra del Fuego or the sterile plains of
central Australia; and they contract to smaller areas dotted with fairly
populous villages in the fertile districts of the middle Congo or
bordering the rich coast fishing grounds of southern Alaska and British
Columbia. But always land is abundant, and is drawn upon in widening
circles when the food supply becomes inadequate or precarious.

[Sidenote: Influence of small confined areas.]

Where nature presents barriers to far-ranging food-quests, man is forced
to advance from the natural to the artificial basis of subsistence; he
leaves the chase for the sedentary life of agriculture. Extensive
activities are replaced by intensive ones, wide dispersal of tribal
energies by concentration. The extensive forests and grassy plains of
the Americas supported abundant animal life and therefore afforded
conditions for the long survival of the hunting tribes; nature put no
pressure upon man to coerce him to progress, except in the small
mountain-walled valleys of Peru and Mexico, and in the restricted
districts of isthmian Central America. Here game was soon exhausted.
Agriculture became an increasing source of subsistence and was forced by
limited area out of its migratory or _essartage_ stage of development
into the sedentary. As fields become fixed in such enclosed areas, so do
the cultivators. Here first population becomes relatively dense, and
thereby necessitates more elaborate social and political organization in
order to prevent inner friction.

The geographically enclose