Oldest DNA shows 2 million-year-old life in Greenland
Even though the DNA was broken up into tiny pieces, scientists were still able to piece together genetic information.
The earliest DNA ever found was used by scientists to reconstruct what life was like in northern Greenland two million years ago.
Whereas presently it is a desert in the Arctic, in the past, it was a verdant forest home to many species of creatures, including the mastodon, which has since become extinct.
Author and University of Copenhagen glaciologist Kurt Kjaer commented, “The work opens the door into a past that has been basically forgotten.”
Since animal fossils are so challenging to come by, the team turned to soil samples in order to collect environmental DNA (eDNA).
This refers to the DNA fragments that are released into the environment when an organism dies or decays.
Since DNA degrades over time, studying really ancient DNA often requires studying very small bits of the original DNA.
However, with the help of cutting-edge technology, geneticist and senior author Eske Willerslev of the University of Cambridge was able to extract data from the fragmented, damaged DNA.
The research team looked for genetic connections between the DNA and that of other animals in a paper published Wednesday in Nature.
The samples were collected from the Kap Kbenhavn formation in Peary Land. According to Kjr, the region is now a polar desert.
Willerslev, however, noted that this region had a period of significant climatic change that caused temperatures to rise millions of years ago.
Tens of thousands of years passed as sediment accumulated at the site before the environment cooled, cementing the discoveries into the permafrost.
The DNA fragments would be preserved in the chilly setting until scientists began to drill them out in 2006.
The researchers noted a remarkable diversity of plant and animal life in the region during the warm period, when average temperatures were 20 to 34 degrees Fahrenheit (11 to 19 degrees Celsius) higher than today.
Fragments of DNA indicate a combination of plants that thrive in colder areas, like birch trees and willow shrubs, and those that do better in warmer climes, like firs and cedars.
Animals are as diverse as geese, hares, reindeer, and lemmings were detected in the DNA.
According to Willerslev, a dung beetle and the bones of a hare were the only previous evidence of animal life at the location.
According to Kjr, the discovery of DNA from the mastodon, an extinct animal that resembles a cross between an elephant and a mammoth, was a significant shock.
North America’s temperate woodlands have yielded many fossilized mastodon remains.
According to Willerslev, that’s a lot of further south and across an ocean from Greenland.
Love Dalen, an evolutionary genomics researcher at Stockholm University who was not involved in the study, stated, “I wouldn’t have, in a million years, anticipated discovering mastodons in northern Greenland.”
Researchers were also able to learn about marine life during this time period thanks to the sediment that accumulated at the fjord’s entrance.
According to Kjr, the DNA evidence indicates that horseshoe crabs and green algae once thrived in the area, which suggests that the waters were likely much warmer back then.
Benjamin Vernot, an ancient DNA researcher at Germany’s Max Planck Institute for Evolutionary Anthropology who was not involved in the study, said that the study illustrates some of the advantages of eDNA by extracting dozens of species from just a few sediment samples.
With this method, “you truly get a bigger view of the environment at a certain period,” as Vernot put it.
You can study the plant without tracking down this piece of wood, and the mammoth may be examined without tracking down this bone.
Laura Epp, an eDNA expert from the University of Konstanz in Germany who was not involved in the work, stated that it is difficult to establish with certainty if these species genuinely lived side by side or whether the DNA was mixed together from different sections of the landscape.
However, according to Epp, this type of DNA study is helpful in revealing the “hidden diversity” of long-lost landscapes.
Willerslev thinks their DNA could offer a “genetic roadmap” to help us adapt to present warming because these plants and animals lived through a time of extreme climate change.
Dalen of Stockholm University anticipates that ancient DNA research will continue to go further and further back in time.
He participated in the examination of DNA extracted from a mammoth tooth that held the previous record for “oldest DNA,” estimating its age at roughly a million years.
If you can discover the correct samples, Dalen says, “I wouldn’t be astonished if you can go at least one or probably a few million years further back.”
Source: The Hindu