Appleyard counts the world's gray hairs:

In a new book, Peoplequake, the science writer Fred Pearce provides startling evidence [of the demographic change taking place]. The average citizen of the world is currently less than 30; yet, when he dies, that average age will have risen to 50.

The average age in Britain is 39 and rising, although it may stabilise or fall if mass immigration continues. Thanks to a crash in its birth rate, in the space of 30 years Italy has gone from being Europe’s youngest country to its oldest; after Japan, it is now the second oldest country in the world. There are only 1.3 Italian taxpayers to each pensioner.

For reasons that are not always clear, birth rates are plummeting across the world. Meanwhile, people are living longer. Life expectancy has soared. The global figure a century ago was 30. Today, it is 66, with the Japanese, the longest-lived, surviving on average to 79 for men and 86 for women. Surprisingly to most demographers, life expectancies are continuing to increase. Whether we like it or not, the world is rapidly growing more wrinkled.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.