ASPEN, Colo.—Throughout human history, plotting populations by age group has yielded a pyramid. Across societies, the young (the base) exceeded the old (the tip).
But in recent decades, these pyramids have been morphing into rectangles and other previously unseen shapes. Just look at how the age breakdown of the U.S. population is expected to change between 1950 and 2060, in the GIF below. As early as 2030, the percentage of Americans 65 and older could surpass the percentage that is younger than 15.
"This is uncharted water," according to Paul Taylor, who researches demographic and generational changes at the Pew Research Center.
This trend isn't confined to the United States. Between 2010 and 2050, global population growth is forecast not only to slow but also to be strongest among older age groups (the phenomenon is blunted somewhat by rapid population growth in regions such as Africa).
In fact, the shifts are even more pronounced in some European and Asian countries than they are in America. Demographers anticipate that by 2050, the majority of people in countries such as Japan, South Korea, and Germany will be older than 50.
By mid-century, China, in part because of its one-child policy, will have an age pyramid resembling a "top-heavy trapezoid," Taylor said in a talk on Saturday at the Aspen Ideas Festival, which is organized by the Aspen Institute and The Atlantic. In Germany, deaths have exceeded births every year for the last four decades. And the most dramatic manifestation of the phenomenon is in Japan.
"Japan has among the lowest birth rates in human history," Taylor explained. "It has among the greatest advances in human longevity in human history. And, frankly, it doesn't cotton to immigrants all that much. Immigration tends to make countries younger."
There are reasons to cheer the shifting shape of age around the world. For example, rectangle-shaped breakdowns are primarily the result of longer life expectancy and lower birth rates, which in turn reflect advances in medicine and family planning. But the trendlines are also worrying on a number of levels. Fewer working-age people could slow economic growth. Grayer populations could put a greater strain on the earth's resources and force people to work well into old age rather than retire.
Most alarming, working-age people in developed countries are supporting an increasing number of dependents, threatening social-welfare services. It's the reason why programs like Social Security and Medicare, in their current form at least, are unsustainable for future generations of Americans.
"Today, 10,000 Baby Boomers will turn 65. And tomorrow, another 10,000 Baby Boomers will turn 65. And the next day, and so on every single day between now and 2030," Taylor said. When members of this generation go from being taxpayers to beneficiaries, "you suddenly have a social compact between old and young that doesn't work anymore." A top-heavy rectangle is a poor foundation for a social safety net.