April 1, 2008

Light Shed on Woolly Mammoth Extinction

Climate change and human development played key roles in the eventual extinction of ancient woolly mammoths, according to a Spanish study released in the journal PLoS Biology on Tuesday.

The cold-adapted mammals had survived previous warming periods, but the species was ultimately weakened following a climate increase during the Holocene epoch that made them susceptible to human expansion.

"The collapse of the climatic niche of the mammoth caused a significant drop in their population size, making woolly mammoths more vulnerable to the increasing hunting pressure from human populations," the researchers wrote.

When the climate began to gradually become warmer and wetter in the mid-Holocene, the habitat of the woolly mammoth shrunk and vegetation in the region was transformed.

Coincidentally, it was during this time that humans began to expand across northern Eurasia. While researchers were able to confirm that humans and mammoths coexisted, they noted that evidence of hunting by humans is scarce.

David Nogues-Bravo, a researcher at Museo Nacional Ciencias Naturales in Spain, who led the study, said the debate over the cause of the woolly mammoth's extinction has been long and vigorous.

He said it was difficult to pin-down the most crucial factor leading to the mammoth's destruction.

In 1967, scientist Paul Martin of the University of Arizona claimed that humans armed with primitive weapons killed off the remainder of the animals who had previously not encountered people.

Researchers reported that humans would have had to kill one woolly mammoth each every three years to cause the animal to fall into extinction. This was based on printed and online source records collected by the team.

"Our analyses suggest that the humans applied the coup de grace and that size of the suitable climatic area available in the mid-Holocene was too small to host populations able to withstand increased human hunting pressure," the researchers wrote.

Commonly referred to as the woolly mammoth, Mammuthus primigenius was an herbivorous mammal that resided in the steppe-tundras of the Northern Hemisphere from late Middle Pleistocene. They are thought to have become extinct on Wrangel Island, Arctic Siberia 3.7 ky ago.


On the Net:

"Climate Change, Humans, and the Extinction of the Woolly Mammoth"