“Today we are in an era of unprecedented demographic divergence, with population trends moving simultaneously in different directions. Some countries are beginning to experience population decline, while others continue to grow rapidly,” says Elizabeth Leahy Madsen, formerly the senior research associate at Population Action International (PAI). In this primer video from ECSP, Madsen explains how global demographic trends affect economic development, national security, and foreign policy.

Three forces drive demographic change:

1. Fertility, which is the average number of children born to each woman, and has the greatest impact on demographic trends;
2. Mortality, which fortunately has declined enough worldwide, so now most children survive to reach adulthood; and,
3. Migration, which has much lower global impact on population size than fertility and mortality, but can have a larger impact at the local level.

Most developed countries reached replacement-level fertility rates (around 2.1 children per woman) in the 1950s. Many countries, including the United States, support family planning programs across the developing world, which have had very significant impacts, particularly on fertility rates in South Asia and Latin America. “But this decline has not been true everywhere,” Madsen says. Fertility rates in sub-Saharan Africa, for example, have declined very slowly – by just one child per woman over the last 40 years.

Demographic projections are based on this history but also assume some convergence toward a common fertility rate (at or below replacement level). The UN projects thousands of different scenarios to come up with high, medium, low, and constant-fertility estimates for each country. For example, the constant fertility estimate for Nigeria, which assumes no change in current total fertility rate (5.61), puts population in 2050 at 504 million. But the medium variant projection, which assumes total fertility rate will fall to 3.2 by 2050, estimates a population of 390 million.

Youth and Capacity Building

“These figures provoke an important question,” says Madsen. “Do these governments have sufficient resources and sufficient willpower to provide for populations that are growing this quickly? And if not, are they likely to reach that capacity in the coming decades?”

“Today we have the largest generation of young people in history, with more than half the world’s population under 30. The vast majority of youth live in developing countries where they will continue to comprise the largest share of the population. The opportunities that are available or not available to these young people will determine their country’s futures.”

Understanding age structure can help us understand trends in governance, democracy, and civil instability. “In a country with a large youthful population, there’s little opportunity cost to joining a rebel group because there are few other alternatives and this facilitates recruitment,” says Madsen.

Adding an Arrow to the Analytical Quiver

Madsen cites the work of demographer Richard Cincotta, who has developed a model for predicting when a country is more likely to start to transition to a liberal democracy based on a historical analysis of age structure and previous transitions. Cincotta’s model predicted that Tunisia would begin such a transition this year, but the still-youthful population age structure of other Middle Eastern countries agitating for change, such as Egypt and Yemen, make a successful transition less likely or very unlikely.

“Demographic analysis, in combination with other political and economic factors, helps identify countries at risk,” Madsen explains. PAI found that 80 percent of all new civil conflict between 1970 and 2007 occurred in countries with at least 60 percent of the population under age 30.

Though Madsen cautions that age structure is never a sole factor for conflict, it does encompass a great many other indicators. And “unlike other social sciences, demography allows for a fairly informed projection into the future,” she says, which makes it a very useful tool for analysts.

“Population trends pressure governments and can facilitate the opportunities and motivation for participation in insurgency,” Madsen concludes. “To counter this, governments needs to scale up the provision of education and jobs for young people. This will be a challenge for many countries, which suggests that demographic projections should be an important component of development and foreign policy planning.”