Researchers estimate that mammoths disappeared from North America’s mainland 10,000 to 14,000 years ago. But they persisted on St. Paul for millennia after that. The animals also survived — for even longer — on Wrangel Island, deep in the Russian Arctic. Researchers there have found teeth that are only 4,000 years old; the Wrangel mammoths were alive as Egypt erected its great pyramids.
Like Wrangel, St. Paul hasn’t always been an island. At the peak of the last ice age, around 21,000 years ago, it was a volcanically active spot on the southern edge of the Bering Land Bridge. Mammoths, saber-toothed cats, short-faced bears and other large animals, or megafauna, roamed the passage between North America and Eurasia. Then, around 11,000 years ago, the climate began to warm and sea level rose, swallowing the land bridge and turning the area into an island over the next 2,000 years. The mammoths were trapped, but their very isolation may have protected them — at least for a while.
Researchers debate what caused the mammoths to die out on the mainland at the end of the last ice age. Some say it was the changing climate, while others argue that humans were the culprits, hunting mammoths to extinction.
Even within Graham’s team, there’s a friendly difference of opinion. “To me, one of the telling patterns is that the timing of extinction around the world roughly corresponds to the timing of human migration dispersion around the world,” says Williams, who sees humans as the major culprits. On the mainland of North America, the arrival of humans, climatic changes and the mammoth’s extinction happened at roughly the same time. But mammoths weathered many other climatic shifts over the hundreds of thousands of years they roamed Earth, Williams notes.
Graham, on the other hand, thinks climate was the driving force. Humans may have sped things up, he says, but mammoths and other Ice Age megafauna were on their way out anyway. “I think the extinctions would have occurred whether humans came or not,” he says. He believes each climate shift that the mammoths survived actually weakened the species, pushing them closer to extinction.