Genghis Khan got lucky with the weather. So did Mark Zuckerberg, says the Pulitzer-winning author of ‘Guns, Germs, and Steel’

At 88, Jared Diamond has metal spikes installed in front of his house.

He put them there, he told Fortune, to protect against angry anthropologists.

“Half of anthropologists have been very helpful to me,” Diamond cheerily said in a Zoom interview from his office in Los Angeles, “and half resent the fact that I — a gallbladder physiologist who happened to have learned a lot about languages and genetics — am trespassing on their specialty.” He called them a “contentious lot,” adding, “they’ve been really nasty.” It’s a well-earned position for Diamond, the contrarian who won a Pulitzer for his smash 1997 non-fiction hit Guns, Germs, and Steel .

Trained as a physiologist at Cambridge, he built a second career studying birds in New Guinea and a third in history and geography.

Now Diamond has published what he calls his final book: Profits, Prophets, Coaches, and Kings , out this fall from Mariner Books.

The argument at its center is one he has been circling since childhood — shaped, he said, by growing up in Hitler’s world.

He writes in the book’s prologue of his family of Jewish immigrants from Eastern Europe and a wife who lost many Polish relatives to the Holocaust.

Do individual leaders actually change the course of events, or are they, as Tolstoy put it, history’s slaves? Diamond points to how only 20% of his neighboring Angelenos bother to vote for the city’s mayor—evidence of a widespread, unexamined conclusion that leaders don’t, in fact, matter.

Boards of directors, on the other hand, pay chief executives hundreds of millions of dollars a year on the belief that they matter very much.

He points to UCLA again, which has spent over $150 million buying out coaches’ contracts since the legendary John Wooden days. (The book has a chapter on the strange alchemy of the Wizard of Westwood.) “I could have told the chancellor [not to do that],” Diamond said, “but they never asked me, that the losing records of every one of our basketball coaches are what you expect from throwing dice.” The industry decides Diamond frames his book as a rejection of both poles of a century-old historical debate.

On one side fits Thomas Carlyle’s “ Great Man theory ,” the idea that history is essentially the biographies of major players.

On the other is Tolstoy’s view, dramatized in War and Peace , that leaders are essentially puppets of forces too large and diffuse to control.

For business leaders, Diamond’s analysis leans on what he calls “natural experiments,” a method borrowed from epidemiology and field biology: when researchers can’t ethically run controlled trials, they look for situations where nature runs them anyway.