Oldest DNA from northern Greenland shows elephant relatives in the region | Polarjournal
Here in Independence Fjord in North Greenland, buried in the ground and covered by ice and snow, samples provided Kurt Kjaer and Eske Willersley’s team with a view of the region going back 2 million years, setting completely new standards. Photo: NASA

In the vastness of the Arctic regions, hidden under rocks, boulders, sand, ice and snow, lie numerous puzzle pieces that allow researchers to glimpse the Arctic’s past. But finding such places is not only a science in itself, but also involves a lot of luck. An international research team has landed an incomparable bull’s eye in the far north of Greenland, discovering fossils and especially genetic material that takes one’s gaze back two million years and holds great surprises.

An open forest of birch, poplar and thuja in a landscape dominated by grasses, bushes and herbs, in the middle of it all mastodons, an extinct species of elephant relatives, with geese flying overhead, and in the coastal waters horseshoe crabs and corals on the seabed: this is what the far north of Greenland looked like two million years ago. This is the result of a study by an international research team led by Dr. Kurt Kjaer, Dr. Mikkel Winther Pedersen from the University of Copenhagen and Professor Eske Willersley from the University of Cambridge. Their sensational discovery into the past was published today in the prestigious journal Nature. “A new chapter spanning one million extra years of history has finally been opened and for the first time we can look directly at the DNA of a past ecosystem that far back in time,” Professor Willersley enthuses.

The research team owes its findings to the discovery of so-called eDNA (environmental DNA) from sedimentary deposits in the “Cape København” formation in the extreme north of Greenland, which is of interest to geologists. At the entrance to Independence Fjord is the ice-free site where researchers had painstakingly collected samples from five different sites repeatedly over the past 16 years. These samples were rich in organic material and remained frozen thanks to the icy conditions of the region. It was already known from previous studies that the place must once have been greener and richer in species. But it was only thanks to the application of the latest methods for analyzing eDNA and comparison with other already identified sites in the Arctic that the research team was able to look 2 million years into the past, which is a new record. “The ancient DNA samples were found buried deep in sediments that had formed over 20,000 years,” Kurt Kjaer explains. “The sediment was eventually preserved in ice or permafrost and, crucially, not disturbed by humans for two million years.”

This tweet from Mikkel Winther Pedersen, one of the study’s lead authors, shows a rendering of the region where the 2-million-year-old DNA was discovered, as it looks today and appeared 2 million years ago. The images were created by Beth Zaiken.

The team discovered in a total of 41 usable samples that, in addition to relatives of present-day Arctic representatives such as reindeer and various plants, rodents, hares, ants and even mastodons had once lived in the region. Mastodons were once a widespread group of elephant-related animals in North America. The find in Greenland is accordingly also spectacular for paleontologists, as this is the northernmost find of these animals. It also indicates that the region must have once been accessible from the south, but how and where is still unclear. Another aspect results from the mixture of animal species discovered. The conditions that existed for the mastodons, insects, and many plant groups discovered through the samples would actually be difficult for reindeer to endure.

From the DNA remains, researchers also hope to learn more about the adaptations of the organisms at the time. That’s because it could also reveal more about the adaptability of present-day species like muskoxen to rising temperatures in the Arctic. Image: Dr Michael Wenger

The fact that reindeer lived in the same region as mastodons opens up new possibilities and questions for researchers, based on the material discovered and the circumstances of how it was preserved. For on the one hand, it provides information on whether and how species might adapt to such warm conditions. “The data suggest that more species can evolve and adapt to highly variable temperatures than previously thought,” says Mikkel Winther Pedersen. “But, crucially, these results show they need time to do this.” And in the opinion of many experts, that time is now running short. But Kurt Kjaer is thinking one step further here: “It is possible that genetic engineering will mimic the strategy that plants and trees developed two million years ago to survive in a climate characterized by rising temperatures and prevent the extinction of some species, plants and trees.” Thus, looking into the Arctic past might also provide a better view of the future.

Dr Michael Wenger, PolarJournal

Link to study: Kjaer et al (2022) Nature 612 (283-291) A 2-million-year-old ecosystem in Greenland uncovered by environmental DNA; doi.org/10.1038/s41586-022-05453-y

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