How Do We Achieve World Peace? We Get Older

The world is experiencing an era of unprecedented demographic change. Due to major reductions in fertility levels and significant increases in life expectancies over the course of the last century-and especially since the end of the Second World War-almost all countries are growing older. By 2073, the United Nations predicts that there will be more people ages 65 and older in the world than under 15, which will be a historical first.

Analysts and policymakers frequently criticize population aging's domestic costs, especially likely slowing economic growth and massive new public expenditures for elderly welfare. But aging has a major yet largely unrecognized international benefit:  it significantly increases the likelihood of international peace, according to a new study published in International Security co-authored by Dr. Mark Haas at Duquesne University.

Haas, a professor of political science and endowed chair in international relations, worked with researchers from Dartmouth College and the University of Albany at the State University of New York to examine how countries' demographic profiles affect their likelihood of going to war. The study finds that younger societies are more likely to become involved in international conflicts while older societies are much more peaceful.

According to the study, countries with large numbers of young people (ages 15 to 24) as a percentage of the total adult population are more likely to engage in international hostilities than ones with older populations. With a surplus of military-aged citizens, soldiers are cheaper and easier to recruit and replace. Younger populations are also more easily radicalized, especially when the country is poorer with fewer economic opportunities.

"In societies with young populations, many citizens often operate by a 'what do we have to lose?' mentality," says Haas. "There aren't enough jobs. Many young adults may not be married or have children. The result is high capacity and high motives for rebellion and/or violence, which can also lead to international wars."

The reverse dynamics occur in older societies. With populating aging, states are likely to dedicate an increasing percentage of their budgets to spending on elderly welfare, which is likely to reduce expenditures in all other areas, including on the military.  Moreover, with fewer military-age citizens, soldiers can demand higher salaries, making them more expensive to recruit and replace. Governments of older societies are therefore less likely to jeopardize their soldiers by engaging in conflict.

"We found that societal aging significantly reduces the likelihood of international aggression," explains Haas. "Because much of the world, including all of the great powers, is aging, demography is likely to be an important source of international peace over the course of the twenty-first century." 

While the U.S. population is aging, it is doing so at a slower pace than its main international rivals, China and Russia. For example, while America's working-age population (ages 15 to 64) is forecasted to increase by 13% by 2050, Russia's is expected to decline by 23% and China's by 18%. These very different demographic trajectories give the U.S. a substantial comparative advantage, both economically and militarily. 

The United States' major demographic advantages are, however, tightly connected to immigration. The Pew Research Center projects that immigrants and their descendants will account for 88% of U.S. population growth through 2065. Consequently, "the current domestic contestation over immigration policies places a lot at stake in terms of the U.S.'s geopolitical positioning," says Haas. "The outcomes of this debate could have major implications for US economic growth, military power and relative dominance worldwide."

Duquesne University

Founded in 1878, Duquesne is consistently ranked among the nation's top Catholic universities for its award-winning faculty and tradition of academic excellence. Duquesne, a campus of nearly 9,500 graduate and undergraduate students, has been nationally recognized for its academic programs, community service and commitment to sustainability. Follow Duquesne University on Facebook, Twitter and Instagram.
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