The advanced age of many world leaders came into sharp focus in 2024, when 81-year-old Joe Biden was pressed to withdraw from America’s presidential race over concerns about his mental acuity. Americans then elected Donald Trump who, at 78, is no spring chicken.

Mr Biden is far from the world’s oldest leader. Paul Biya, who has led Cameroon since 1982, is now 91 years old. The world’s two most populous countries, China and India, also have leaders in their 70s.

Going into 2025, the world’s leaders are, on average, older than ever. Over the past five decades, the average age of all leaders has risen from 55 to 62.

The trend in democratic countries, however, is the opposite. The average age of freely elected leaders is 59, a bit younger than fifty years ago. In 1975, no democratic country’s leader was under 45. Today, three are.

Some are older, too: in 1975, no leader of a democratic country was older than 75. Now five have passed this milestone, including Mr Biden and his successor.

America is an outlier among democracies. Not only is it electing older presidents, its legislators are the oldest in the world. The new administration is unlikely to change that.

Meanwhile, the worldwide trend toward ageing leaders is largely being driven by autocracies. The average dictator is now 64—12 years older than in 1975. This isn't surprising, as autocratic leaders have historically been reluctant to give up power.

Advances in medicine over the past 50 years have allowed leaders to live longer, with 11 autocrats today aged over 75.

But the same forces letting leaders live longer affect the general population, too. While the average leader is seven years older than 50 years ago, the average age of citizens has risen by eleven years.