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Countries with Aging Populations May Be More Peaceful than Younger Societies

July 17, 2019 – In recent months, news reports in China and the United States have noted with concern that the fertility rates in these countries have fallen to record lows. (China’s current fertility rate is now the lowest since 1961, while the U.S. fertility rate in 2018 was the lowest ever recorded). Although societal aging is likely to reduce economic growth, older societies may make the world more peaceful according to a Dartmouth-led study in International Security. Countries with more young people (ages 15 to 24) however, are more prone to international conflict than countries where populations are proportionally older. The study was the first systematic examination of how changing demographics affect a country’s likelihood to go to war.

The study also noted that while the U.S. is getting older, it is aging much less rapidly than its main geopolitical rivals.  The U.S. is expected to see increases in both its working-age population (ages 25 to 64) and military-age cohort (ages 15 to 24) while China and Russia are expected to experience declines among both of these age groups. As the article reports, “from 2010 to 2050, the number of those ages 15 to 64 in the United States is expected to grow by 13 percent, while Russia’s working-age population is predicted to decline by 23 percent and China’s by 18 percent.” These trends provide the U.S. with two demographic advantages: a young workforce is good for economic development and a large military-age population means that the U.S. can keep its military personnel costs down and slate those funds towards other areas of its defense budget.

Aging Map
Source: United Nations, “World Population Prospects: The 2017 Edition” (New York: UN Department of Economic and Social Affairs/Population Division). Figure 2 from the study.

“Our study shows how aging populations may enhance peace and stability in Asia, Europe and the Middle East. The world is essentially comprised of two demographic worlds— regions with mostly stable older societies, where conflicts are unlikely to be an issue; and regions with mostly younger societies, which appear to be more vulnerable to conflict,” explained Stephen G. Brooks, a professor of government at Dartmouth.

With aging populations, states are likely to shift funds from military spending to welfare spending, resulting in what the researchers refer to as a “crowding out” effect. With older populations and low levels of fertility, the military pool shrinks and the per unit labor costs per soldier increase, making countries more averse to conflict.

The study finds that conflict is more likely in countries with younger populations, most of which are very poor. With a bleak economy and few opportunities for employment, the government may work to harness nationalism to defuse civic unrest.  Moreover, youth are more likely to join rebel groups to challenge the status quo. These dynamics create conditions for the likelihood of a rebellion, and civil conflicts may in turn lead to international conflicts, as foreign countries may be inclined to intervene.

The results demonstrate that the probability of international conflict peaks at a median age of 20 and drops by one-quarter of its peak value by a median age of 30.

Conflict Probability
The probability of conflict in relation to media age. Figure 4 from the study. Chart provided by study co-authors, Deborah Jordan Brooks, Stephen G. Brooks, Brian D. Greenhill, and Mark L. Haas.

Looking at other demographic indicators, the study finds that the probability of conflict peaks when a woman has five births and falls to one-third of the peak level when a woman has two births. In turn, the likelihood of conflict increases as life expectancy approaches 58 years but falls drastically at 75 years.

Although global aging is likely to be a force for peace among the great powers in the long-term, Brooks cautions that it might well produce instability in the short-term: “We’ve never had a rising power that grew old before it rises, as in the case of China or a military superpower like Russia that’s about to become very old,” added Brooks. “These changes introduce a new set of dynamics in world order, where we will see if either of these two great powers opt to capitalize by lashing out before they grow extremely old and become far less able to project military power,” he added.

Although the U.S. is expected to benefit from the peace-promoting effects of global aging, the researchers caution that this is not guaranteed, especially if the U.S. pulls back from the world and fails to continue its “deep engagement” strategy, which hinges on honoring its “security commitments to partners in Europe, East Asia and the Middle East.” Furthermore, Brooks notes that many of America’s demographic advantages could well be placed in jeopardy if it significantly restricts immigration, as the Pew Research Center projects that immigrants and their descendants will account for 88 percent of U.S. population growth through 2065.

Stephen G. Brooks is available for comment at: stephen.g.brooks@dartmouth.edu. The study was co-authored by Deborah Jordan Brooks at Dartmouth, Brian D. Greenhill at Rockefeller College at the University at Albany at the State University of New York, and Mark L. Haas at Duquesne University.