Male Mammoths Didn't Have Anyone to Ask for Directions and Died More Often Because of It

A woolly mammoth skeleton. Peter Macdiarmid/Getty Images

Male mammoths were more likely than female mammoths to wander off on their own and then die, a new study suggests.

The first inkling of that finding arose after paleontologist Love Dalen noticed there were many more males than females among a handful of wooly mammoth remains he was studying. "Fairly early, when we started looking at this and doing the samples we had, we realized it was way more males that were killed then we were expecting," Dalen told Newsweek. He studies the genetics of ancient species at the Swedish Museum of Natural History.

Since mammals tend to give birth to about the same number of male and female offspring, the sex ratios Dalen was finding among his samples were puzzling. Dalen and his colleagues then tracked down more samples—98 in all. And the males kept pouring in. All told, Dalen and his colleagues identified more than twice as many males as females from the remains they were able to track down. That sex ratio held true both in mainland Siberia and on Wrangel Island, where the very last mammoths to walk the Earth lived and died. The team report the results of the analysis in a new article published in the journal Current Biology.

"It seemed very odd that there were so many males," Dalen said. "But then we started thinking about it a bit more carefully I guess and it started to make more sense." The secret, he and his colleagues believe, isn't in mammoth births—it's in mammoth lives and mammoth deaths.

After all, scientists have discovered the remains of only a small fraction of all the woolly mammoths that ever lived. While those could theoretically be a representative, random sample, there's no rule to how death and preservation works that dictates it must be so.

Most of the woolly mammoths scientists have studied died in what's called a natural trap—perhaps by falling through a thin sheet of ice over a lake and drowning, or accidentally wandering into a bog and getting stuck. Those conditions are very bad news for the mammoth, of course, but very good news for paleontologists, since they can keep carcasses in good condition for tens of thousands of years.

A baby female mammoth that was found by scientists in Siberia. Kazuhiro Nogi/AFP/Getty Images

And looking at mammoths' closest living relatives, it makes some sense that males might encounter these natural traps more often than females. Elephant herds today are made up of females, led by the eldest, most experienced female. Males have some social bonds, but are much more likely to wander off on their own. That could put them at higher risk of natural traps than females traveling with older, more experienced relatives who might know to avoid getting caught.

"You do expect males in general to be more risk-taking," Dalen said. "But the second component is of course the social structure in the woolly mammoth or at least in elephants, where you have these female-dominated herds that are led by an old matriarch."

He adds that this trend likely didn't shape how mammoths actually went extinct—just modern scientists' perception of what the mammoths we have were doing when they died.

Hannah Osborne contributed reporting to this article.