It’s a long-held sexist stereotype. Now, the prestigious British Medical Journal, no less, asserts that there’s truth to it: Men really can be idiots.

In fact, in a study released December 11, the authors reveal to the world their new “Male Idiot Theory,” or MIT: “Men are idiots, and idiots do stupid things.”

The authors came to their conclusion after analyzing more than 300 winners of the annual Darwin Awards over the past 20 years. Winners of the award are chosen for dying in such monumentally idiotic ways that the human race, they argue, is better off without them in the gene pool. More than 88 percent were men.

Winners, the study notes, include a man who shot himself in the head with a “spy pen” weapon to show his friend it was real. A man who hitched a shopping cart to the back of a train thinking he’d get a free ride home, only to be dragged two miles to his death. And a terrorist who mailed a letter bomb, and when it was returned for insufficient postage, opened it.

The idea for the study, “The Darwin Awards: Sex differences in idiotic behavior,” came from one of the report authors, Ben Alexander Daniel Lendrem, a 15-year-old student in Newcastle in the UK, who is now the youngest author published in the august medical journal, according to his father and second author, Dennis Lendrem, a statistician who studies decision making at the Institute of Cellular Medicine.

Ben was fascinated by the royally stupid ways people offed themselves in the Darwin awards, and, as he was regaling his father with “macabre” tales of fatal idiocy, pointed out that most of the winners were men. So the father and son and two other co-authors analyzed the data and found that that, indeed, was true.

They expected that more men than women would die stupidly. A raft of research has found that men get into more car crashes than women. They’re admitted to Emergency Rooms for accidents and injuries more often. They’re more physically and verbally aggressive. They’re more likely to drive fast, to commit crime, to climb mountains, skydive, use drugs, take risks and act impulsively.

They just didn’t expect that nearly 90 percent of the winners would be men.

“The size of the difference between men and women is what really surprised us,” Dennis said. “It was much bigger than we expected.”

Just why men behave in more idiotic ways than women, however, remains a puzzle not only for the report authors, but for scientists who study evolution, sex differences, genetics, human behavior and psychology.

“Presumably, idiotic behavior confers some, as yet unidentified, selective advantage on those who do not become its casualties,” the Lendrems write. “Until MIT gives us a full and satisfactory explanation of idiotic male behavior, hospital emergency departments will continue to pick up the pieces, often literally.”

Indeed, picking up the pieces of men who’ve done idiotic, risky or impulsive things is what one of the report co-authors, Andy Gray, a consultant trauma surgeon, actually does. “Usually every Friday or Saturday night,” Dennis said.

Anne Campbell, a psychologist who studies evoltion and sex differences at Durham University, said the evolutionary argument goes like this: “Males (of many species) engage in far more risk-taking behaviour as a result of their greater fitness variance (bigger difference between male winners and losers in terms of reproduction compared to females) and the fact that their investment in offspring is not obligate,” she wrote in an email. “Female mammals need to stay alive to ensure their infants survival (and thus their own reproductive success).”

In other words, male idiocy can get them the girl.

The Lendrems said examples of male idiocy abound, not just in the Darwin awards. Consider TV shows like Jackass, the BBC’s World’s Craziest Fools with Mr. T. And Tosh. 0, which gives people a chance at “web redemption” after posting videos on the Internet of them doing stupid things that usually go very, very wrong. Like the guy who jumped off a 100-foot cliff during spring break, and nearly missed the lake. (“Don’t do it, you idiot!” one girl screamed as she watched the failed jump from below.)

“It may be that in the past, males have found themselves in situations where those rapid reaction impulsive behaviors are adaptive, to ensure survival. I’m thinking in fights or battle, or when, trying to take down a saber-tooth tiger, those kinds of situations,” Dennis Lendrem said.

But why men may be inclined to idiocy in the 21st century? “We really don’t know, is the honest answer.”