When President Biden abandoned his re-election campaign this month, citing the need to “pass the torch to a new generation,” some of the most envious accolades he received came from 6,000 miles away.

In central Africa, in coastal Cameroon, many are longing for their president, Paul Biya — at 91 the world’s oldest leader — to take a leaf out of President Biden’s book. But most think he never will.

“He’ll do everything to remain in power,” said Lukong Usheno Kiven, a human rights advocate based in Yaoundé, the capital of Cameroon, where Mr. Biya has been in power for 42 years.

Mr. Biya is just one of dozens of notably aged leaders who are also far older than the populations they serve.

Presidents Xi Jinping of China and Vladimir V. Putin of Russia are both 71. India’s prime minister, Narendra Modi, is 73. Israel’s leader, Benjamin Netanyahu, is 74, while Mahmoud Abbas, the president of the Palestinian Authority, is 88.

But it is in Africa — the world’s youngest continent — where the gerontocracies are most stark. Eleven of the world’s 20 oldest leaders are African, according to research done by the Pew Research Center.