DeathscytheX
May 10th, 2006, 10:34 PM
No link, email from professor.
From the Toronto Star:
Humans cleared of killing off woolly mammoths
Last Updated Wed, 10 May 2006 14:13:18 EDT
CBC News
Climate shifts, not over-hunting, killed off the woolly mammoth and
wild horse, a carbon-dating study suggests.
* FROM NOV. 12, 2003: Climate tied to horse extinction
What caused the animals to become extinct at the end of the last Ice
Age more than 10,000 years ago has been one of prehistory's greatest
whodunits. Biologists have often pointed the finger at over-hunting by expanding
populations of humans.
But new radiocarbon dates give a more precise account of what happened
at the time of the mass extinctions, and shift the focus to global
warming.
Paleobiologist Dale Guthrie analyzed bone samples from bison, moose and
humans, which lived through the extinction period, and from wild horse
and mammoth, which did not survive. The more than 600 samples were
recovered in Alaska and the Yukon. He also studied preserved samples of pollen from
the period.
He found that by the time Homo sapiens started pushing into the region
around 12,300 years ago, the wild horse had already died out and woolly
mammoth were in decline.
Meanwhile, populations of bison, moose and white-rumped elk called
wapiti were increasing, said Guthrie, professor emeritus with the Institute of
Arctic Biology at University of Alaska, Fairbanks.
By analyzing pollen samples, he concluded that a naturally occurring
shift in climate caused the animals to change their diet.
Like their modern cousins, the wild horses and the woolly mammoth of
the past had a large intestinal pouch, or caecum, suited to feeding on
low-quality forage on the steppe.
But as the frozen landscape thawed, higher-quality grasses started to
grow. Those grasses were favoured by the bison and wapiti but were
indigestible to the mammoth, Guthrie suggested.
His results were published in Thursday's edition of the journal Nature.
From the Toronto Star:
Humans cleared of killing off woolly mammoths
Last Updated Wed, 10 May 2006 14:13:18 EDT
CBC News
Climate shifts, not over-hunting, killed off the woolly mammoth and
wild horse, a carbon-dating study suggests.
* FROM NOV. 12, 2003: Climate tied to horse extinction
What caused the animals to become extinct at the end of the last Ice
Age more than 10,000 years ago has been one of prehistory's greatest
whodunits. Biologists have often pointed the finger at over-hunting by expanding
populations of humans.
But new radiocarbon dates give a more precise account of what happened
at the time of the mass extinctions, and shift the focus to global
warming.
Paleobiologist Dale Guthrie analyzed bone samples from bison, moose and
humans, which lived through the extinction period, and from wild horse
and mammoth, which did not survive. The more than 600 samples were
recovered in Alaska and the Yukon. He also studied preserved samples of pollen from
the period.
He found that by the time Homo sapiens started pushing into the region
around 12,300 years ago, the wild horse had already died out and woolly
mammoth were in decline.
Meanwhile, populations of bison, moose and white-rumped elk called
wapiti were increasing, said Guthrie, professor emeritus with the Institute of
Arctic Biology at University of Alaska, Fairbanks.
By analyzing pollen samples, he concluded that a naturally occurring
shift in climate caused the animals to change their diet.
Like their modern cousins, the wild horses and the woolly mammoth of
the past had a large intestinal pouch, or caecum, suited to feeding on
low-quality forage on the steppe.
But as the frozen landscape thawed, higher-quality grasses started to
grow. Those grasses were favoured by the bison and wapiti but were
indigestible to the mammoth, Guthrie suggested.
His results were published in Thursday's edition of the journal Nature.