Scientists have located the oldest DNA ever discovered, revealing in the process a complex ecosystem that existed 2 million years ago in modern-day Greenland, according to the findings of a new study published in the journal Nature.
Deoxyribonucleic acid (or DNA for short) is a double helix found in almost every cell of our human bodies, and those of the plants and animals that live on our planet.
Each DNA molecule inside contains a genetic code that is unique to each individual, and serves as a vital guidebook for our cells that helps control how our bodies develop and function. It’s also an incredibly useful molecule for scientists looking to decipher the mysteries of the ancient past.
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This is because researchers are able to determine what kinds of animals or plants were present during a particular window in Earth’s evolutionary history by looking for snippets of DNA in well-preserved samples dating back in some cases hundreds of thousands of years.
Once these specimens are identified, scientists can match the genetic codes found in the DNA with their closest modern-day counterparts, in order to determine what kind of animal or species they belonged to. In this way, humanity can build a picture of entire ecosystems that have been lost to the relentless passage of time, and gain valuable insights into the evolution of life on our planet.
Unfortunately, this technique is limited by the lifetime of the DNA molecule. Once cells begin to die, enzymes work to break down the bonds that hold these vital molecules together. Under normal conditions for animals, this decomposition process will render the DNA useless in about 521 years.
However, when the right conditions allow DNA to be preserved quickly and stably, specimens have been known to live longer.
In the new study, scientists were able to recover 41 ancient DNA samples from the mouth of a fjord located at the northernmost point of Greenland, where the landmass meets the Arctic Ocean. Each of the DNA samples extracted from the rock — known as the Copenhaven Formation — was just a few millionths of a millimeter long, and was encased in a protective shell of clay and quartz.
By applying a combination of radiocarbon and molecular dating techniques, the international team of more than 40 scientists was able to estimate that the DNA was, on average, about 2 million years old. This makes her a million years older than the previous record holder for ancient DNA, which was recovered from the bones of a Siberian mammoth.
“Ancient DNA samples were found buried deep in sediments accumulated over 20,000 years,” comments Professor Kurt Keijer of the University of Copenhagen, who helped lead the research. “The sediments were eventually preserved in ice or permafrost and, more importantly, were not disturbed by humans for two million years.”
After painstakingly comparing the DNA with data from the 21st century, the team was able to decipher the fingerprints of a thriving ancient ecosystem locked inside the samples.
At the time the København Formation was created about two million years ago, Greenland was a much more hospitable place, with temperatures roughly 10 to 17 degrees Celsius warmer than they are today.
DNA evidence revealed the presence of countless types of plant life in the ancient environment, including forms of poplars and birches. Among these trees roamed rodents, reindeer, hares, and even giant elephant creatures called mastodons. There were also fragments of DNA that could not be matched to any modern-day animal or plant.
Many samples have been awaiting analysis since they were first collected from the Greenland site in 2006.
Professor Keier explained: “It was not until a new generation of DNA extraction and sequencing equipment was developed that we were able to identify and quantify very small, damaged fragments of DNA in sediment samples.” capable of mapping a two-million-year-old ecosystem.”
The scientists behind the new study believe that the relatively warm environment of ancient Greenland is comparable to the temperatures we could see in the future as a result of global warming. Modern-day climate change is a serious threat to biodiversity on a global scale, and the rate at which species can adapt to changing environments and rising temperatures will be fundamental to their survival.
“The data suggests that more species can evolve and adapt to wildly varying temperatures than previously thought,” said Associate Professor Mikkel Pedersen of the Lundbeck Foundation GeoGenetics Centre, co-first author of the new paper. “But, crucially, these results show that they need time to do so.”
It is hoped that by analyzing the DNA of ancient trees and plants, scientists will be able to unlock the secrets of how they adapted to their hot environment, and perhaps learn how to make today’s endangered species more resilient to climate change.
Moving forward, the team hopes to discover more examples of truly ancient DNA in the mud from Africa that could shed light on humanity’s early ancestors.
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Anthony is a freelance contributor covering science and video game news for IGN. He has more than eight years of experience covering breaking developments in multiple scientific fields and there is absolutely no time to fool you. Follow him on Twitter @BeardConGamer
Image credit: Beth Zaiken
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