The world’s oldest piece of DNA was found in northern Greenland, and researchers have used it to piece together a picture of what life was like there two million years ago. Back then, it was a verdant area full with trees and plants that was home to a variety of species, including the mastodon, which has since become extinct. Today, it is a desolate wasteland in the Arctic.
Due to the scarcity of animal fossils, the researchers decided to extract environmental DNA, commonly known as eDNA, from samples of soil instead. This refers to the genetic content that organisms expel into their surroundings, such as through their hair, excrement, saliva, or the corpses of dead animals that are decomposing. The genetic material degrades over time, leaving researchers with just teeny-tiny shards to work with, which can make it difficult to do research on extremely ancient DNA.
Eske Willerslev, a geneticist at the University of Cambridge and the study’s principal author, noted that researchers were able to extract genetic information from the fragments of damaged DNA that were so minuscule because they used the most recent technology. Scientists did this in their study, which was published on Wednesday in the journal Nature. Specifically, they were seeking for similarities between the DNA of various animals and their own.
According to Willerslev, however, this region went through a period of extreme climatic change many millions of years ago, which caused temperatures to rise. At the location, sediment had most likely been accumulating for tens of thousands of years prior to the environment becoming cooler and cementing the discoveries into permafrost.
The chilly climate would help protect the tiny bits of DNA until scientists came along and drilled the samples out starting in 2006. Before that, the delicate bits of DNA would have a better chance of being lost.
According to the findings of the researchers, during the warm period of the region, when the average temperatures were 20 to 34 degrees Fahrenheit (11 to 19 degrees Celsius) greater than they are today, the area was home to an extraordinary variety of plant and animal species. The DNA pieces point to the possibility of a hybridization between plants that are typically found in milder climes, such as firs and cedars, and arctic flora, such as birch trees and willow shrubs.
In addition, there was evidence that the DNA came from creatures such as geese, hares, reindeer, and lemmings. According to Willerslev, the only indications of animal life that had been found at the location in the past were the remnants of a hare and a dung beetle.
According to Kjaer, the discovery of DNA from an extinct animal called the mastodon, which looks like a cross between an elephant and a mammoth, was one of the biggest surprises. A significant number of mastodon fossils have been discovered in the temperate forests of North America in the past. This location is a significant amount further south and is separated from Greenland by an ocean.
Researchers were able to glean information about the marine life that existed during this time period from the sediment that accumulated at the mouth of a fjord during this time period. Based on the DNA, it appears that horseshoe crabs and green algae once called this location home. The fact that the study was able to identify dozens of species from only a few sand samples underlines some of the benefits of using eDNA.
According to Laura Epp, an expert in environmental DNA from the University of Konstanz in Germany who was not involved in the work, it is difficult to determine for certain if these species genuinely existed side by side, or if the DNA was combined together from various areas of the landscape, based on the evidence that is now available.
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