Do You Know What A Population Pyramid Is?

Mike Magee

If you take a look at the map, you can see that Africa, and to a lesser extent for South and Southeast Asia and Central America, have relatively high numbers of individuals who are young. Gary Fuller in 1995 described this as a “youth bulge”1995. Some have suggested that an excess in especially young adult male population was associated with social unrest, war and terrorism. Others have countered since that the “youth bulge” is not purely determinative, that other factors and circumstances including governance, environment, mobility, disease, and opportunity are equally important. Still few deny that high populations of under-employed, under-educated, and under-advantaged youth create a demographic challenge often leading to mass unrest. (1,2)
One easy way to visualize youth bulges is through the population pyramid, a graphical illustration which consists of two side-by-side bar graphs with males on the left and females on the right organized in 5 year cohorts. The X-axis shows population size and the Y-axis shows age.

A range of professionals use these population graphs to define populations by age and sex, to shed light on the extent of development of a nation, and to define how many people of each age range live in the area. Females tend to predominate due to their longer life expectancy. Fertility and mortality levels may be reflected. For example a pyramid with a broad base and a rapidly narrowing point suggests a high birth rate, a high death rate and a short life expectancy – conditions often present in a developing nation with little birth control, a lack of clean water or sanitation, and little access to health care.

Population pyramids are also used to define levels of dependency, pegging those populations below 15 and above 65. This knowledge can be critical for government sponsored social services to support vulnerable and fragile members of their societies. Looking at a nation’s population period over time exposes trends, and has also been used to peg levels of development over time.

The four stages above have been used historically. In stage one, in an under developed society, death rates and birth rates are high and roughly in balance. In stage two, as the nation develops, death rates drop as food and water supply and sanitation improve, decreasing disease rates. Farming techniques improve, as does basic healthcare, education and access to technology. Countries in this stage experience a large increase in population. Stage three is marked by economic deveolpment and with it an increase in wages, urban migration, modern agriculture, increases in the status and education of women, decreased child labor and increased education, and increased contraception with declining birth rates. Population growth begins to level off. In stage four birth rates and death rates decline. As an example, birth rates in modern times dropped below replacement levels in Germany, Italy, and Japan, leading to shrinking populations, creating human resource challenges for thriving industries.

Here are a few population pyramids:

Afghanistan shows a classical youth bulge.
China had an extreme youth bulge until the 1960s, altered in part by their one-child policy.

USA demographics have been on the move. (click on map to activate changes from 1950 to 2050)

In spite of development, broad public policies and behaviors toward nutrition, smoking, environmental and safety regulation and tobacco can conspire to increase chronic disease burden. In these cases, gains in life expectancy may halt, and quality of life may decline even as quantity rises.

For Health Commentary, I’m Mike Magee.

References:

1. Goldstone, Jack A.: “Revolution and Rebellion in the Early Modern World”, Berkeley 1991
2. Fuller, G: “The Demographic Backdrop to Ethnic Conflict: A Geographic Overview”, in: CIA (Ed.): “The Challenge of Ethnic Conflict to National and International Order in the 1990s”, Washington 1995, 151-154
3. “Youth – An Undervalued Asset: Towards a New Agenda in the Middle East and North Africa, Progress, Challenges and Way Forward,” Middle East and North Africa Region Human Development Department (MNSHD), The World Bank, 2007
4. Fuller,G. The Demographic Backdrop to Ethnic Conflict: A Geographic Overview, was born in 1989 and was produced by Edward Gewin: The Challenge of Ethnic Conflict to National and International Order in the 1990s, Washington: CIA (RTT 95-10039, October), 151-154.