The question left open by economists is what the consequences will be of such a large surplus of young men. History offers a disquieting answer. According to the German scholar Gunnar Heinsohn, European imperial expansion after 1500 was the result of a male “youth bulge.” Japan’s imperial expansion after 1914 was the result of a similar youth bulge, Heinsohn argues. During the Cold War, it was youth-bulge countries—Algeria, El Salvador, and Lebanon—that saw the worst civil wars and revolutions. Heinsohn has also linked the recent rise of Islamist extremism in countries like Afghanistan, Iraq, and Pakistan to an Islamic youth bulge. Political scientists Valerie Hudson and Andrea den Boer warn that China and India could be the next countries to overdose on testosterone.

That has scary implications. Remember, most of Hemingway’s stories in Men Without Women are about violence. They feature gangsters, bullfighters, and wounded soldiers. The most famous story is called simply “The Killers.”

It may be that the coming generation of Asian men without women will find harmless outlets for their inevitable frustrations, like team sports or videogames. But I doubt it.