Oldest DNA samples found on Greenland

[milmor_1]

Oldest DNA samples found on Greenland
By Steve Connor, Science Editor
Published: 06 July 2007
The world's oldest DNA samples, retrieved from beneath a mile-deep cap of ice, have revealed a "lost world" of forest animals and plants that once thrived on Greenland before it became a frozen desert.

Muddy sediments from the bottom of a 2km (1.2 mile) ice core have, for the first time, provided direct evidence that Greenland was covered in a dense forest teeming with flora and fauna less than a million years ago. Scientists have extracted fragments of DNA estimated at 450,000-900,000 years old from a rich variety of organisms. These include beetles, butterflies and moths.

It is the oldest authenticated DNA to be recovered from ancient biological material and represents a triumph for scientists trying to reconstruct past habitats destroyed by climate change.

"We have shown for the first time that southern Greenland, which is hidden under 2km of ice, was once very different to the Greenland we see today. Back then, it was inhabited by a diverse array of conifer trees and insects," said Professor Eske Willerslev of the University of Copenhagen, who led the research team.

"This genetic material presents a biological environment which is completely different to today. We have found grain, pine, yew and alder. These correspond to the landscapes we find in eastern Canada and in Swedish forests today," Professor Willerslev said.

"The trees provide a backdrop from which we can also ascertain the climate since each species has its own temperature requirements. The yew trees reveal that the temperature during the winter could not have been lower than minus 17C and the presence of other trees shows that summer temperatures were at least 10C," he said.

The study, published in the journal Science, shows that the Greenland ice cap has existed continuously, in some form or other, for many hundreds of thousands of years longer than previously supposed, given that the last organisms to live there have been shown to be so ancient.

"These findings allow us to make a more accurate environmental reconstruction of the time period from which these samples were taken. We've learnt that this part of the world was significantly warmer than most people thought," said Martin Sharp, a glaciologist at the University of Alberta.

The discovery appears to disprove the theory that Greenland had been ice-free around 125,000 years ago when the global climate was about 5C warmer than it is today. The study suggests the ice cap has been in place for at least 450,000 years.

Professor Willerslev said the findings indicate the ice sheet may be more stable than was thought. "This may have implications for how the ice sheets respond to global warming. We know that, in the last interglacial, sea levels rose by 5-6m, but this must have come from other sources, such as the Antarctic ice. I would anticipate that, as the earth warms from man-made climate change, these sources would still contribute to a rise in sea levels," he said.

Dr Sharp added: "It could mean our current warming is the result of natural processes and human influences. We may be heading for bigger temperature increases than we thought."

Oldest DNA samples found on Greenland - Independent Online Edition > Sci_Tech

[conlor]

I wonder why this wasn't done before. It's very cool!

Maybe they'll finally find Yeti!