The age distribution is a major source of variation among human populations. In general, populations with a high proportion of young dependents have a high death rate and a low birth rate, while populations with a high proportion of older persons have a low death rate but a high birth rate. The population of a nation is grouped into 3 broad categories:
- Children (generally below 15 years): They are economically unproductive and need to be provided with food, clothing, education and medical care.
- Working Age (15—59 years): They are economically productive and biologically reproductive. They comprise the working population.
- Aged (Above 59 years): They may be working voluntarily but they are not available for employment through recruitment.
