Metagenomics under 2 kilometers of ice

Andrew Curry profiles ancient DNA researcher Eske Willerslev, of the University of Copenhagen. Willerslev is best known for the characterization of chloroplast and mitochondrial DNA from old tundra cores, and this week's paper interpreting local biotic diversity from Greenland ice cores.

Willerslev began to wonder about the ignored ice core bottoms in the building his lab shared with Steffensen's climate research group. "I did the permafrost stuff, and then suddenly it hit me: Silty ice is icy permafrost, right?" Judiciously cutting and melting the core bottoms, Willerslev and his colleagues analyzed the resulting water for signs of DNA. What Willerslev found, and reports on page 111, broke his own record for the oldest DNA ever recovered, and promises to rewrite the history of Greenland's climate. His team identified and dated genetic sequences from coniferous trees, butterflies, beetles, and a variety of other boreal forest plants--traces of ancient forests that Willerslev says covered southern Greenland perhaps as far back as 800,000 years ago.

The paper itself is interesting and brief -- Willerslev and colleagues found DNA from boreal forest tree and insect species at the bottom of a 2-km ice core from south-central Greenland. The trick was dating the thing, and using 4 different methods they conclude the ice is between 500,000 and 1 million years old.

References:

Willerslev E and 29 others. 2007. Ancient Biomolecules from Deep Ice Cores Reveal a Forested Southern Greenland. Science 317:111-114. doi:10.1126/science.1141758