The Cycle of Cosmic Catastrophes:
Flood, Fire, and Famine
in the History of Civilization
by Richard Firestone,
Allen West, and
Simon Warwick-Smith
Posted on 06/11/2007 10:35:44 AM PDT by blam
Aren’t the Russians trying to clone a mammoth from frozen DNA ?
Monday 17 December 2007
How forests wiped out woolly mammoths
Last Updated: 12:01am GMT 16/12/2007
Woolly mammoths were among the biggest mammals to have walked the earth, but it appears they were driven into extinction by nothing more dangerous than trees.
A leading expert on the ice age will claim this week that, rather than being wiped out by human hunters, the giant creatures were doomed by the spread of forests around the world at the end of the last ice age 10,000 years ago.
Professor Adrian Lister, a palaeobiologist at University College London, has found that the extensive areas of frozen grassland on which mammoths thrived were gradually replaced by forests, leaving the animals nothing to eat.
Analysis on the DNA extracted from hundreds of fossils has revealed that the genetic differences between individual mammoths were so slight that the animals were unable to adapt to the changes in their environment.
It contrasts with previous theories that humans hunted the woolly beasts into extinction or that rising temperatures left them unable to cope. Prof Lister will present his findings at the annual meeting of the Palaeontological Association in Sweden on Monday.
He will reveal a detailed picture of how mammoths first evolved about seven million years ago in tropical Africa, migrated north and adapted to the cold that allowed them to thrive in the ice age before dying out.
“In the middle of the last ice age, around 30,000 years ago, there were millions of mammoths roaming over a huge area,” said Prof Lister. “Around 20,000 years later there were hardly any left.
“As the forests moved in, the mammoths were pushed out of their normal habitat. These animals are mostly governed by vegetation rather than climate and so they were squeezed into very small populations as the forests took over the cold grasslands.
“I don’t think that people played a major role in wiping them out, although they may have pushed those final populations over the edge. The major impact factor was the change in the vegetation from grassland to trees.”
Prof Lister, with colleagues at the Natural History Museum and the Royal Holloway in London, analysed hundreds of mammoth fossils, extracting and comparing DNA sequences.
He said: “The DNA we have been able to extract from mammoth bones is like a clock and allows us to trace the evolutionary story in great detail now.”
American research revealed last week that mammoths and other great beasts from the last ice age were blasted by meteorites. Tusks from Alaska, 35,000 years old, were found to have been peppered with fragments.
Richard Firestone, of the Lawrence Berkeley National Laboratory, believes that this impact, along with another 13,000 years ago, caused big mammals such as the mammoth to disappear.
He said: “These large animals were particularly exposed to the shockwave produced by a large impact and had few places of refuge where they might have survived.
“There are probably strong parallels to the demise of the dinosaurs.”
Woolly giants: grazers of the frozen grassland
Weighed eight tons and reached 11ft tall.
Tusks of up to 11ft long were used to clear snow.
Ate more than 300lb of grass a day.
Four inches of fat, and hair up to 3ft long insulated them from the cold.
Closest living relative is the Asian elephant.
Perfectly preserved baby mammoth was found in Siberia last year.
© Copyright of Telegraph Media Group Limited 2007
The Cycle of Cosmic Catastrophes:
Flood, Fire, and Famine
in the History of Civilization
by Richard Firestone,
Allen West, and
Simon Warwick-Smith
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