Population pyramid

[1] Males are usually shown on the left and females on the right, and they may be measured in absolute numbers or as a percentage of the total population.

[2] It is also used in ecology to determine the overall age distribution of a population; an indication of the reproductive capabilities and likelihood of the continuation of a species.

The measures of central tendency (mean, median, and mode) should be considered when assessing a population pyramid.

A series of population pyramids could give a clear picture of how a country transitions from high to low fertility rates.

There are usually more females than males in the older age ranges since, for a variety of reasons, women have a greater life expectancy.

Lastly, in stage five, the pyramid starts to take on the shape of a kite as the base continues to decrease.

Gunnar Heinsohn (2003) argues that an excess in especially young adult male population predictably leads to social unrest, war, and terrorism, as the "third and fourth sons" that find no prestigious positions in their existing societies rationalize their impetus to compete by religion or political ideology.

Heinsohn claims that most historical periods of social unrest lacking external triggers (such as rapid climatic changes or other catastrophic changes of the environment) and most genocides can be readily explained as a result of a built-up youth bulge.

In general, youth bulges in developing countries are associated with higher unemployment and, as a result, a heightened risk of violence and political instability.

[16] To reverse the effects of youth bulges, specific policies such as creating more jobs, improving family planning programs, and reducing overall infant mortality rates should be a priority.

"[18] Structural changes in service provision, especially health care, beginning in the 1960s created the conditions for a demographic explosion, which has resulted in a population consisting primarily of younger people.

In turn, this declining dependency ratio can have a positive impact on overall economic growth, creating a demographic dividend.