Cavemen innocent in MAMMOTH MURDER case: DNA evidence
It was the climate wot done it, reckon Swedish researchers
Boffins have claimed that the demise of the woolly mammoth was caused by climate change, offering up an alternate theory to the premise that its spot on the human menu was to blame for the species' extinction.
British and Swedish researchers examined 300 mammoth carcasses from around the world and found that populations tumbled during warm periods known as interglacials, which fell between chilly ice ages. Populations of the hairy beasts became split up during these long warm spells, with smaller populations clinging on in cold, icy regions in different parts of the world.
In the hotter eras, populations became "extremely dynamic", with numbers of mammoths plunging dramatically in some places and shooting up in others, depending on the climate.
We are currently living in an interglacial period which has lasted since the the end of the Pleistocene Era, the era when modern humans started to use tools. It was previously believed that group of hungry humans used these tools to hunt the slow-moving mammoths to extinction.
“We found that a previous warm period some 120,000 years ago caused populations to decline and become fragmented, in line with what we would expect for cold-adapted species such as the woolly mammoth”, said Eleftheria Palkopoulou from the Swedish Museum of Natural History, who was lead author of the report.
During this ancient heatwave, when sea levels were high and the climate was roughly as warm as it is today, mammoths became confined to small, cold areas.
“This suggests that spells of warm climate made the mammoth more susceptible to extinction”, said Dr Love Dalén, who also works at the Swedish Museum of Natural History.
This population fragmentation also led to the development of a unique type of mammoth in Europe, which existed when the continent was frozen solid.
The team found that a genetically distinct species of European mammoth was then muscled out by Siberian mammoths when the world froze about 30,000 years ago.
The Russian mammoths' reign last about 16,000 years, until the world once again began to warm.
“It thus seems likely that environmental changes played a significant role in shaping the woolly mammoth's demographic history, with warm periods restricting the amount of available habitat and cold periods leading to population expansions,” the report said.
Now the team wants to resolve why the mammoth survived "in refugia"(a phrase used to denote small pockets of once common animals) during early interglacials but not the Holocene, the name for the current warm period we are living through.
"To understand why the species as a whole became extinct, we therefore must look more closely into these final places where mammoths survived, such as St. Paul and Wrangel Islands [in the Bering Sea]”, added Dr. Ian Barnes from Royal Holloway University, London.
The report is titled Holarctic genetic structure and range dynamics in the woolly mammoth and was published by the Royal Society. ®
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