Chapter 2: Global Demography: Population size and Age Characteristics

Population changes are measurable phenomena that are more and more being measured in all countries. They are also, given time, controllable by restrictive, expansive, or eugenic population policies. Thus, if the effect on international relations of such changes proved to be determinate, statesmen would have at their disposal a means both for predicting and controlling international relations. ‘As the incidence of war and peace overshadows most other social, economic, and political problems, this would be no small convenience in every field of affairs.

Unfortunately, it appears that no such determinate relation exists. A general increase in the world’s population may lead to closer cooperation among peoples, or it may lead to more friction and war between peoples. Extreme differentials in the density of population in different areas may lead to mutually advantageous exchanges and peaceful interdependence, as is customarily found in the relations between the city and the rural areas of a country, or in the relations between the motherland and a young migration colony. Population differentials may, however, lead to tension, mass migration, aggression, wars and conquest, as did the relation of Europe to the American Indians in the sixteenth and seventeenth centuries. A country whose population is growing more rapidly than its neighbours may start a war of conquest and a country whose population is growing less rapidly than its neighbours may start a preventive war, or neighbouring countries whose population rates are very different may live at peace.

Population changes, like climatic changes, geographical and geological discoveries, and technological and social inventions, greatly influence political behaviour; but the more “civilized” peoples become, the less determinate is this relationship. Among primitive peoples, possible alternatives are limited, definite and predictable. It may be said that these people behave under “necessity” although ethnological investigation proves that the behaviour is dictated, not by physical or physiological laws, but by tribal custom. These patterns have sometimes prescribed war or migration in case of population pressure. When desert Arabs increased in population beyond their pasturage, they raided their neighbours. When desiccation reduced the pasturage of nomads of the Steppes, great hordes moved into the agricultural areas of Russia or China. When a Pacific island became overcrowded, certain Polynesians took to their boats to find new islands. But, as Hiller points out, “whether there shall be feticide or infanticide, parricide, human sacrifice, blood feuds or war, is largely a matter of the mores.” But what the mores say, it is necessary for the tribesman to do.