Population often is said to be the biggest problem facing the world. However, precisely what this problem is varies, depending on whether the issue is meeting basic human needs, the stress placed on the natural environment by increased consumption, changes in family structures, or demographic transitions within nations. Population is at once a conceptual, scientific, technological, ethical, and political issue.

Definitions

The simple definition of population as the total number of persons in a geographic area indicates the relativity of population to sometimes arbitrary boundaries. Other relevant factors in population studies are fertility, mortality, and mobility; empirical studies of those factors are often difficult to pursue and are subject to contentious interpretative frameworks. Scientific theories of population growth and its relationship to social stability or economic development often rely on intuitive or "commonsense" views that have not proved reliable. The influence of technologies on population growth or delimitation...