Aging Populations
Countries that successfully complete the Demographic Transition Model face a new problem on the other side: not enough young workers to support a growing number of retirees.
An aging population is one where the proportion of elderly people is growing relative to younger age groups — visible directly in a population pyramid as it shifts from a wide base to something narrower and more top-heavy. This is a natural consequence of reaching Stage 4 or Stage 5 of the Demographic Transition Model: birth rates that have stayed low for decades mean each new generation is smaller than the last, while people live longer than ever.
The economic strain is direct: a shrinking working-age population must support a growing number of retirees through pensions and healthcare systems, pushing the dependency ratio up even in wealthy, developed countries. Japan is the most frequently cited real-world example — decades of low birth rates combined with long life expectancy have made it one of the most aged societies on Earth.
Governments facing this pressure typically reach for a combination of tools: pro-natalist incentives to raise future birth rates, increased immigration of working-age adults to fill labor gaps immediately, automation to reduce reliance on human labor, and raising the official retirement age so more people stay in the workforce longer. No single policy tends to be enough on its own — aging populations are usually addressed with several strategies at once.