In the quarter century the Wilson Center’s Environmental Change and Security Program has been pondering the issues for which it’s named, the world’s demographic future has been wobbling. A key concern of analysts: How many people will farmers need to feed in 2050? Mainstream projections have teetered between 8.9 billion and 9.8 billion, amounting to an increase of between 13 and 21 percent over today’s 7.7 billion. This significant variation in projections is rarely acknowledged by prognosticators. Many simply round up today’s latest guess and state confidently that there will be 10 billion people in 2050—though just a few years ago, the number most confidently stated was 9 billion.

First published 30 years ago in the National Interest, Francis Fukuyama’s landmark essay, “The End of History?,” argued that, with the fall of fascism and communism, no serious blueprint for modern-state development lay open, save for those paths that would ultimately embrace both political and economic liberalism. Over the past two decades, movement toward this ideal end-state has trickled to a halt. Instead, the political elites of Eurasia’s regional powers—Russia, Turkey, Iran, and China—have crafted stable illiberal regimes that borrow whatever they need from free-market economics, electoral politics, nationalism, and religion. Their ascent has produced a form of “non-endpoint stability”—two mutually antagonistic camps: one composed of liberal democracies, the other a mix of illiberal hybrids. As long as these camps remain stable, the international system falls far short of Fukuyama’s theoretical end of history.

Exactly 25 years ago the international community met in Cairo for the 1994 International Conference on Population and Development. In the aftermath of the Cold War, ethnic conflict seemed to be exploding globally and research on the role of population growth and resource scarcity found an eager audience among policy makers struggling to understand this new international disorder. ECSP’s founding in that same year positioned the program as a leader in bringing together the scholarly and policy communities around non-traditional security issues over the last 25 years. The last two-and-a-half decades have brought tremendous change in population trends, environmental change, and the security landscape. Over the next 25 years three trends will shape the agenda of those working on the nexus of population-environment-security issues.

With rapidly aging populations and rising levels of female employment, the United States and other wealthy nations are facing unprecedented demands for non-familial care. These nations vary in their ability to address such demands. Those with more robust welfare states, including publicly supported, high-quality child care and elder care services and facilities, are generally able to meet growing needs for care, while those with weaker welfare states experience severe “care deficits,” leaving families with few alternatives. Increasingly, in the United States and elsewhere in the developed world, families are turning to migrants—usually women—to solve their care dilemmas.

This year, 2018, marks the 60^th anniversary of a landmark publication by a pair of academic social scientists who first recognized the close relationship between population age structure (the distribution of a country’s population, by age) and development. In Population Growth and Development in Low Income Countries (Princeton U. Press, 1958), demographer Ansley Coale (1917-2002) and economist Edgar M. Hoover (1907-1992) theorized that eventual declines in fertility would transform developing-country age structures. Coale and Hoover demonstrated that these newly transformed age structures would exhibit larger shares of citizens in the working ages, and smaller shares of dependent children and seniors (Fig. 1). This transition, they argued, would someday help lift countries with youthful populations in Asia, Latin America, and Africa out of the low-income bracket.

As populations age, countries around the globe are beginning to focus attention on unpaid caregivers. Such people typically spend hours each day bathing, feeding, and helping an elderly or disabled relative. Often, they undermine their own health and career to take care of a loved one.

In Judy Brady’s iconic essay, “I Want a Wife,” the feminist activist enumerates the dozens of practical and emotional tasks wives perform as a matter of duty. At the end, she asks: “My God, who wouldn’t want a wife?”

The silver tsunami is approaching: Many countries, not all of them rich, are facing the challenges of an ageing population thanks to growing life expectancies and shrinking birth rates.