Two-million-year-old DNA has been identified for the first time, which “will change the rules of the game” of evolution, admit the authors of this study published in the journal Nature🇧🇷
They achieved this thanks to the discovery of microscopic fragments of environmental DNA in Ice Age sediments in northern Greenland. The development of current technology has made it possible to define that they are one million years older than the previous record, coming from DNA extracted from a Siberian mammoth bone.
This genetic information was used to map an ecosystem from two million years ago that underwent extreme climate change. The researchers hope the results could help predict the long-term environmental consequences of the current climate emergency.
A new chapter of over a million years of history has finally opened and, for the first time, we can directly observe the DNA of an ecosystem so far away in time.
Eske Willerslev of the University of Cambridge
“A new chapter spanning over a million years of history has finally opened, and for the first time, we can directly observe the DNA of an ecosystem from so far back in time,” says Eske Willerslev, co-leader of the research at St. John’s College at the University of Cambridge (UK).
Artist’s impression of the Kap København formation today / Beth Zaiken
Sediment at the mouth of a fjord
The incomplete samples, measuring just a few millionths of a millimeter, were obtained from the København Formation, a sedimentary deposit almost 100 meters thick located at the mouth of a fjord in the Arctic Ocean, at the northernmost point of Greenland. In all, they collected 41 useful samples found hidden in clay and quartz.
“The ancient DNA samples were found buried in sediments that had accumulated [en aquella época] for 20,000 years. The sediment was ultimately preserved in ice or permafrost and, most importantly, was undisturbed by humans for two million years,” says Kurt H. Kjær, who also leads the work at the Center for Geogenetics at the Lundbeck Foundation at the University of Copenhagen. (Denmark), of which Willerslev is director.
The ancient DNA samples were found buried in a sediment that has not been disturbed by humans for two million years.
Kurt H. Kjær of the Lundbeck Foundation
Greenland’s climate at that time was between 10ºC and 17ºC warmer than it is today. Sediment was piling up meter by meter in a shallow bay. “DNA can degrade quickly, but we’ve shown that, under the right circumstances, we can go back further in time than anyone dared to imagine,” said Willerslev.
The organic layers show traces of the rich plant flora and insect fauna that lived two million years ago in Kap København, in northern Greenland. / urt H. Kjær
Reindeer tracks, lemmis and even mastodons
Scientists have uncovered evidence of animals, plants, and microorganisms such as reindeer, hares, lemmings, and birch and poplar trees; They even discovered that the mastodon, an Ice Age mammal, made it as far as Greenland before it went extinct. Previously, it was thought that the range of these elephant-like animals did not extend as far as Greenland from their known origins in North and Central America.
The research work carried out by 40 researchers from Denmark, the United Kingdom, France, Sweden, Norway, the United States and Germany allowed the secrets of DNA fragments to be revealed. The process was painstaking: first they had to determine if there was hidden DNA in the clay and quartz, and if there was, they could separate it from the sediment for examination.
The answer was finally affirmative. The researchers compared each of the DNA fragments with extensive DNA libraries collected from living animals, plants and microorganisms. Thus began to emerge a picture of the DNA of trees, bushes, birds, animals and microorganisms.
Some of the remains were easy to classify as predecessors of current species, others could only be related to genus, and some came from species that were impossible to locate.
Some of the remains were easy to classify as predecessors of current species, others could only be related to genus, and some came from species that were impossible to locate.
Samples from two million years ago also help scholars gain insight into a previously unknown stage in the evolution of the DNA of several species that still exist today.
A two-million-year-old larch trunk still trapped in permafrost within coastal deposits. The tree was washed out to sea by rivers that eroded the former forest landscape. / Svend Founder
A milestone made possible by technological advances
“Expeditions are expensive and many of the samples were collected in 2006 when the team was in Greenland for another project and have been in storage ever since. It was only when a new generation of extraction and sequencing equipment was developed that we were able to locate and identify fragments of extremely small and damaged DNA in the sediment samples. This means that we have finally managed to map a two-million-year-old ecosystem,” says Kjær.
While reviewing ancient genetic remains from the Kap København Formation, they also found a wide range of microorganisms, including bacteria and fungi, which they continue to map. A detailed description of how the interaction between animals, plants and single-celled organisms worked biologically within the ancient ecosystem of the northernmost point of Greenland will be presented in a future research paper.
The Kap København ecosystem, which has no equivalent today, existed at considerably higher temperatures than today.
Mikkel W. Pedersen of the Lundbeck Foundation
It is now hoped that some of the discovered two-million-year-old plant DNA “tricks” could be used to help make some endangered species more resilient to a warmer climate.
“The Kap København ecosystem, which has no equivalent today, existed at considerably higher temperatures than today. At first glance, the climate appears to have been similar to what we expect on our planet in the future due to global warming”, says Mikkel W Pedersen , co-first author of the paper and researcher at the Center for Geogenetics at the Lundbeck Foundation.
Freshly thawed moss from coastal permafrost deposits. / NIColaj K. Larsen
A new step in DNA detection
One of the factors that most arouses interest in this study is to know the extent to which species are able to adapt to the change in conditions produced by a significant increase in temperature.
“The data suggest that there are more species that can evolve and adapt to highly variable temperatures. But above all, these results show that they need time to do it. The current rate of global warming means that organisms and species do not have that time, so the climate emergency remains a major threat to biodiversity and the world: extinction is on the horizon for some species, including plants and trees”, warns Pedersen.
It is possible that genetic engineering could mimic the strategy developed by plants and trees two million years ago to survive in a climate characterized by rising temperatures and avoid the extinction of some species, plants and trees.
Kurt H. Kjær of the Lundbeck Foundation
Researcher Kjær states: “It is possible that genetic engineering mimics the strategy developed by plants and trees two million years ago to survive in a climate characterized by rising temperatures and avoid the extinction of some species, plants and trees. reasons why this scientific breakthrough is so significant, as it may reveal how to try to counteract the devastating impact of global warming.”
DNA tends to survive better in cold, dry conditions, such as those most prevalent in Kap København’s material.
“Now that we’ve managed to extract ancient DNA from clay and quartz, it’s possible that clay preserved ancient DNA in warm, humid environments in deposits found in Africa,” predicts Willerslev, adding: “If we can start exploring Ancient DNA in grains of clay from Africa, we can gather groundbreaking information about the origin of many different species, perhaps even new insights into early humans and their ancestors – the possibilities are endless.”
Reference:
“A 2-million-year-old ecosystem in Greenland uncovered by environmental DNA”. Nature2022