A lost world in a pinch of dirt
At the northernmost tip of Greenland lies the Kap København Formation, a polar desert landscape. Buried in these sediments, preserved for two million years in permafrost, are microscopic fragments of environmental DNA (eDNA). These fragments—some just a few millionths of a millimeter long—are the genetic remnants of an entire ecosystem. For years, researchers led by Eske Willerslev and Kurt Kjær repeatedly failed to extract these tiny clues from the sediment. Finally, advances in gene sequencing technology allowed them to isolate the ancient DNA from clay and quartz particles it had bonded to.
The result, published in the journal Nature, shattered the previous record for the oldest DNA ever sequenced, which belonged to a one-million-year-old mammoth bone. The Kap København eDNA is twice as old, dating back approximately two million years to a time when northern Greenland was 11-19°C warmer than it is today.
The genetic data revealed a landscape with no modern equivalent: an open boreal forest populated by a strange mix of temperate and Arctic species. DNA from over 100 genera of plants and animals showed poplar, birch, and thuja trees growing alongside Arctic shrubs. The sequences also identified reindeer, hares, lemmings, and geese. Most unexpectedly, the mud contained the DNA of the mastodon (Mammut), an extinct relative of elephants previously thought to have lived only in the forests of North America, thousands of kilometers to the south.
Genetic ghosts and future crops
The discovery of mastodons in Greenland rewrites the known range of the Ice Age mammal. No mastodon fossils have ever been found on the island, so their presence was completely unknown until their DNA appeared in the sediment samples. The ecosystem revealed by the eDNA was a unique blend of species, with temperate-forest animals coexisting with Arctic mainstays like reindeer (Rangifer) and lemmings. Marine eDNA also pointed to the presence of Atlantic horseshoe crabs (Limulus polyphemus), suggesting much warmer coastal waters.
Besides cataloging this vanished world, the ancient DNA offers clues for modern science. Researchers identified a specific gene mutation in the poplar tree DNA. This gene relates to the plant's blue-light receptors, which influence how it captures sunlight—an important function in the high Arctic, with its low sun angle and extreme seasonal light shifts.
This ancient genetic adaptation is now the focus of applied research. In partnership with the Carlsberg Laboratory, scientists are engineering this two-million-year-old gene into modern barley. The experiments aim to determine if the prehistoric poplar's survival trick for low-light conditions can be transferred to modern crops, potentially making them more resilient and productive as the global climate changes.