PLoS Biol. 6, e79 (2008)

Credit: ROB PONGSAJAPAN

The extinction of the woolly mammoth some 3,600 years ago was driven by the disappearance of its icy habitat combined with the emergence of human hunters, scientists have confirmed. The relative importance of climate and hunting for the mammoth's fate has long been debated but rarely assessed quantitatively.

David Nogués-Bravo of the National Museum of Natural Sciences in Madrid, Spain, and colleagues combined climate and population models to unravel the roles of natural and human factors in the demise of the herbivorous mammal. They first inferred the mammoth's 'climate envelope' — the temperature and precipitation limits within which the animals could survive — from simulated paleoclimate data corresponding to the locations and ages of mammoth fossil finds. This defined a tundra environment widespread across northern Eurasia during the mammoth's ice-age heyday 42,000 years ago, which by 6,000 years ago had dwindled to a few isolated outposts as glaciers withdrew.

Although mammoths had weathered similar warm conditions during the previous interglacial period, this time the encroaching warmth brought humans with it. Connecting the habitat map with a mammoth population model, the researchers found that only slight hunting pressure, as little as one kill per year per 200 humans, could have sufficed to destroy the mammoths' few interglacial holdouts.