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

Later, during the iciest part of the ice age 20,000 to 25,000 years ago, the "Last Glacial Maximum," northern woolly mammoth populations declined, likely because the area became too barren to be hospitable. However, during that time, the giants became abundant in the warmer interior parts of Siberia.

"There was an old idea that cold glacial conditions like the Last Glacial Maximum were optimal for mammoths," MacDonald said. "That idea now doesn't really hold water."

Northern refuge

Northern mammoth populations grew after the Last Glacial Maximum, but then dipped again during the Younger Dryas period about 12,900 years ago. Although there is controversy as to what happened at that time, "there was certainly a very rapid and profound cooling of many regions then, followed by rapid warming," MacDonald said. "Did this cause the extinction of the mammoth? Absolutely not. They were still present in far northern sites at the end of the Younger Dryas. Right now it's not quite definitive how great an impact the Younger Dryas had."

The last mammoths seen on the continents were concentrated in the north. They apparently disappeared about 10,000 years ago as the climate warmed and peatlands, wet tundra and coniferous forests developed, environments to which mammoths were poorly suited. The long-lasting proximity between mammoths and humans suggested that our species was perhaps a factor in the beasts' decline, possibly killing off the final island populations of woolly mammoths that went extinct 3,700 years ago.

Overall, these findings suggest the mammoths experienced a long decline due to many factors.

"There was no one event that ended the mammoths," MacDonald said. "It was really the coalescence of climate change and the habitat change that triggered [it], and also human predators on the landscape at the end."

These findings regarding mammoths could shed light on what species today might face in the future. [10 Species You Can Kiss Goodbye]

"Mammoths faced profound climate change and very profound changes in their habitat and landscape, and also faced pressure from humans," MacDonald said. "Now think about the 21st century, where we're seeing rapid climate change, massive changes in the landscape and certainly pressure from humans on the environment. Species today are facing the same sorts of challenges the mammoths did, but the rate of those changes today are much greater than what mammoths faced."

Future research can focus on other animals once plentiful across Beringia, such as horse and bison. The scientists detailed their findings online June 12 in the journal Nature Communications.

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