Population Pyramid - Youth Bulge

See also: Baby Boom and List of countries by median age

The expansive case was described as youth bulge by Gary Fuller (1995). 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, including European colonialism, 20th-century fascism, rise of Communism during the Cold War, and ongoing conflicts such as that in Darfur and terrorism. This factor has been also used to account for the Arab Spring events. Economic recessions, such as the Great Depression of the 1930s and the Late 2000's recession, are also claimed to be explained in part due to a large youth population who cannot find jobs. Youth bulge can be seen as one factor among many in explaining social unrest and uprisings in society.

Youth bulge theory represents one of the most recently developed theories of war and social unrest, and has become highly influential on U.S. foreign policy as two major U.S. proponents of the theory, political scientists Jack Goldstone and Gary Fuller, have acted as consultants to the U.S. government.

A large population of adolescents entering the labor force and electorate strains at the seams of the economy and polity, which were designed for smaller populations. This creates unemployment and alienation unless new opportunities are created quickly enough - in which case a 'demographic dividend' accrues because productive workers outweigh young and elderly dependants. Yet the 16-30 age range is associated with risk-taking, especially among males. In general, youth bulges in developing countries are associated with higher unemployment and, as a result, a heightened risk of violence and political instability. For Cincotta and Doces (2011), the transition to more mature age structures is almost a sine qua non for democratization.

Many countries with the largest youth bulge are African nations severely afflicted by the HIV/AIDS epidemic, which has decreased overall lifespan dramatically. As of 2012, the largest youth bulge is found in Zimbabwe, which has a population structure with 56.57% between the ages of 15 and 29.

• Afghanistan shows a classic youth bulge.

• Angola shows the same, even more pronounced.

• China had an extreme youth bulge until the 1960s, when it sharply curbed partly as an effect of the one-child policy.

• Population pyramid of Egypt in 2005. Many of those 30 and younger are educated citizens who are experiencing difficulty finding work.

• Nearly half of Libya's 2011 population consists of youths under age 20.