That's probably true, as far as it goes, but it doesn't say exactly what ultimately did the beasts in. One theory holds that humans hunted them to extinction. According to Paul Martin's 1967 "Blitzkreig" theory, the retreat of the continental glaciers allowed humans to travel farther north and wipe out the mammoths. Proponents of this theory point to the numerous unearthed mass kill sites and the signs of "spear points among the bones of mammoths," according to Drexel's University Academy of Natural Sciences.
But a study of woolly mammoth DNA has found that the animals still existed for thousands of years after humans moved into their territory. A 2009 report in the Proceedings of the National Academy of Sciences concluded that hunting did have an impact but "did not deliver the deathblow" to the species.
Other scientists look to the sky for an explanation. Pointing to fragments of glassy carbon, microscopic diamonds, and enriched iridium at several sites in the United States and Canada, all buried beneath a layer of soot, decayed plants, and other debris, they speculate that, about 13,000 years ago, a comet exploded over Canada, unleashing a shock wave with a force equivalent to millions of nuclear weapons.
"This event was large enough to directly kill most everything instantly. Those that survived would have found their food sources devastated, their water polluted, all kinds of things that would have made it difficult to go on much longer," Richard B. Firestone, a nuclear chemist at the Lawrence Berkely National Laboratory, told the Washington Post. This event is thought to have contributed to the extinction of the saber-toothed cat, the American camel, and the giant ground sloth.
Is it possible that the woolly mammoth could someday roam the earth again? Evolutionary geneticists could someday clone the woolly mammoth by inserting the nuclei of the long-dead beast into the egg of an Asian elephant. Ethicists may debate the morality of resurrecting extinct species, but nobody would deny that it would make for a very interesting trip to the zoo.