Ancient genome reveals two-million-year-old ecosystem



Pearlyland is an inhospitable place in the extreme north of Greenland. A peninsula so arid that grass never grows and snow never falls, and icy winds sweep across its bare rocks. It is a place where life is hard to imagine.

But exactly that, a living ecosystem, is what scientists are now locating in Pearyland. In this place, where moss, lichen and fungus no longer exist today, a rich fauna and flora grew and thrived two million years ago. Caribou and American mammoths once roamed the tree-lined landscape, horseshoe crabs burrowed through the mud of the shallows, and flocks of geese cackled in the air. The wind played with the leaves of birch and poplar, rabbits hopped through the grass, lemmings dug holes and tunnels to get to the nutritious roots of the grass.

The ancient fauna and flora of Pearyland did not come from the imagination of the researchers – they were able to reconstruct it from ancient DNA preserved in the permafrost. They had previously extracted them from the Cape København geological formation. To do this, they have optimized the previous techniques and made comparisons with existing gene databases. They hope that what they learned about life millions of years ago might even help save species alive today from extinction.

Optimization of the Nobel Prize winning technique

What scientists already knew: Pearyland was less icy in the early Pleistocene. It was much milder there then, the temperatures were about 10 to 17 degrees Celsius higher than today. And the ecosystem was complex: some of the documented animal and plant species now only occur in the Arctic, others in the boreal forests of temperate latitudes. “We are seeing an ecosystem that has no equivalent in modern ecosystems,” says paleogeneticist Eske Willerslev, who researches at the University of Cambridge and is also director of the Lundbeck Foundation GeoGenetics Center at the University of Copenhagen. As he reports with his international research team in “Nature”, he used the method to reconstruct the old DNA that the Swedish researcher Svante Pääbo, who developed at the Max Planck Institute for Evolutionary Anthropology in Leipzig – and for the Pääbo on Saturday the Nobel Prize for Physiology and Medicine is awarded in Stockholm.

The reconstruction of the ancient genome fragments not only reveals a long-forgotten ecosystem, but also breaks a technical record: previously, one million years was the maximum age for DNA reconstruction. Researchers had once succeeded in doing this with genetic material from a mammoth tooth and also once with DNA fragments that were also millions of years old and that were freely available in the environment, i.e. not found in a fossil. But thanks to the technique Willerslev and his team have optimized, scientists can now even get a glimpse of ecosystems that lived two million years ago. You have thus managed to take a giant leap into an even more distant past.



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