London, Apr 19: The discovery of DNA, by far the oldest, from the animals and plants that populated Siberia and Alaska up to 395,000 years ago from specks of permafrost will give scientists unprecedented power to reconstruct ancient ecosystems and track them through time.
The permafrost contained DNA—not yet authenticated—from eight species of mammals including woolly mammoth, steppe bison and musk ox, dating back 30,000 years, as well as 28 families of trees, shrubs, mosses and herbs, some of which lived 300,000 to 400,000 years ago.

Eske Willerslev and his team at the University of Copenhagen in Denmark sampled permafrost along 1200 kilometres of Siberia's Arctic coast. They drilled to depths of 31 metres, removed cores of soil, and then extracted any DNA remaining in the frozen earth, reports NewScientist.


The researchers looked for segments of several vertebrate mitochondrial genes and a plant chloroplast gene, which vary slightly between different species.

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"From just two grams of soil, you can obtain a meaningful sample of the ecosystem," says Willerslev.



Willerslev was particularly struck by the dramatic shift in vegetation revealed in Siberia during the past 400,000 years. Herbs dominated the oldest landscapes but steadily declined until shrubs strongly dominated by about 10,000 years ago. This shift helps explain the mysterious extinction of most of the region's large mammals about 11,000 years.

According to 'New Scientist', previous claims of ancient DNA have been dogged by the problem of contamination. Modern DNA is ubiquitous, and readily sneaks into samples, with the drilling process itself being one possible source of contamination.
Bureau Report