What killed the woolly mammoth? A whole bunch of things, say scientists. (+video)

Woolly mammoths were apparently driven to extinction by a multitude of culprits, with climate change, human hunters and shifting habitats all playing a part in the long decline of these giants, researchers say.

Woolly mammoths (Mammuthus primigenius) wandered the planet for about 250,000 years, ranging from Europe to Asia to North America covered in hair up to 20 inches (50 centimeters) long and possessing curved tusks up to 16 feet (4.9 meters) long. Nearly all of these giants vanished from Siberia by about 10,000 years ago, although dwarf mammoths survived on Wrangel Island in the Arctic Ocean until 3,700 years ago.

Scientists have often speculated over what might have driven the mammoths to extinction. For instance, for years researchers suspected that ancient human tribes hunted the mammoths and other ice age giants to oblivion. Others have suggested that a meteor strike might have drastically altered the climate in North America about 12,900 years ago, wiping out most of the large mammals there, the so-called "Younger Dryas impact hypothesis."

Now an analysis of thousands of fossils, artifacts and environmental sites spanning millennia suggest that no one killer is to blame for the demise of the woolly mammoths.

"These findings pretty much dispel the idea of any one factor, any one event, as dooming the mammoths," researcher Glen MacDonald, a geographer at the University of California, Los Angeles, told LiveScience.

Mammoth database

Scientists investigated the extinction of woolly mammoths living in Beringia, the last refuge of mammoths that nowadays lies mostly submerged under the icy waters of the Bering Strait. To get an idea of woolly mammoth abundance, past climate and other environmental factors, they analyzed samples from more than 1,300 woolly mammoths, nearly 450 pieces of wood, nearly 600 archaeological sites and more than 650 peatlands, compiling their ages and locations to see how these giants and their environments changed over time. They also probed mammoth genetic data found in fossils of the titans.

"There will be people talking about the incompleteness of the fossil record, and there'll always be uncertainties here, no question, but the size of our database is thousands of data points, so I think we can see the general patterns," MacDonald said.

Their results revealed woolly mammoths flourished in the open steppe of Beringia between 30,000 to 45,000 years ago, with its relatively abundant grass and willow trees. The area wasn't as warm then as today, but not as cold as the height of the ice age. "That seemed to be very favorable for mammoths, in terms of abundance," MacDonald said. Humans coexisted with mammoths back then, clearly not driving them to extinction at that time. [Gallery: The World's Biggest Beasts]

1 | 2

Next