Paul Ehrlich is a biologist who has been making dire predictions about the fate of humanity for decades. He has been wrong on every count, yet he still commands attention and influence in the media and academia. This article examines why Ehrlich’s pessimism persists despite the overwhelming evidence of human progress and prosperity.

This article originally appeared in the Wall Street Journal.

Paul Ehrlich’s memoir, “Life: A Journey through Science and Politics,” comes out next week. It probably won’t sell as many copies as “The Population Bomb” (1968). But neither will it flop—and it should. Mr. Ehrlich, 90, whom the media treat with an obsequious deference—see the recent cringe-worthy segment on CBS’s “60 Minutes”—will again profit from the capitalist consumption he’s spent his life decrying.

Mr. Ehrlich is a purveyor of “doom porn” at a time when the world has never been more prosperous. Developed countries are astonishingly rich, and even in developing nations the share of the population in absolute poverty has fallen to single digits. Mr. Ehrlich in 1968 predicted mass starvation; instead obesity is rising, even in Africa. So why don’t people ignore him? Ignorance is no excuse when we carry the entirety of human knowledge in our pockets.

The answer is that humans have evolved to prioritize bad news. “Organisms that treat threats as more urgent than opportunities,” wrote Nobel Prize-winning behavioral psychologist Daniel Kahneman, “have a better chance to survive and reproduce.”

As Peter H. Diamandis and Steven Kotler explain in “Abundance: The Future Is Better Than You Think,” our brains have limited bandwidth and need to focus when a threat arises. Most information is first sifted through the amygdala, a part of the brain that is “responsible for primal emotions like rage, hate, and fear,” Messrs. Diamandis and Kotler write. “The amygdala is always looking for something to fear.”

That is a very powerful impulse that can deceive even the most dispassionate and rational observers. A study by Marc Trussler and Stuart Soroka found that even when people expressly say they are interested in more good news, eye-tracking experiments show they are in fact much more interested in bad news.

Mr. Ehrlich built a career pandering to these inclinations, starting with “The Population Bomb.” In 1970 he said that “if I were a gambler, I would take even money that England will not exist in the year 2000.” That got the attention of Julian Simon, a University of Maryland economist, who a decade later challenged Mr. Ehrlich to a wager.

It was structured as a commodities futures contract. Simon agreed to sell Mr. Ehrlich $200 each worth of chromium, copper, nickel, tin and tungsten in 1990 at 1980 prices. The bet would pay off for Mr. Ehrlich if the metals became scarcer and thus costlier. On the settlement date, the total price had declined from $1,000 to $423.93. Mr. Ehrlich mailed Simon a check for the balance, $576.07.

While issuing one failed prognostication after another, Mr. Ehrlich went on to win a series of prestigious prizes. When the MacArthur Foundation gave him a “genius grant” in 1990, Simon quipped: “MacArthur! I can’t even get a McDonald’s!”

What does Mr. Ehrlich’s memoir say about the bet? The book isn’t out, but its index is already available on Amazon. Simon’s name doesn’t appear.