The oldest DNA ever discovered reveals a thriving ecosystem lost to time

The oldest DNA ever discovered reveals a thriving ecosystem lost to time

Scientists have identified the oldest DNA ever discovered, revealing a complex ecosystem that existed in modern-day Greenland two million years ago, according to the results of a new study published in the journal Nature.

The double-helical molecule of deoxyribonucleic acid (or DNA for short) is present in nearly every cell of our human body, and those of the plants and animals that inhabit our planet.

Each DNA molecule contains a genetic code that is unique to each individual and serves as an essential instruction manual for our cells that helps determine how our bodies develop and function. It is also an incredibly useful molecule for scientists who want to decipher the secrets of the distant past.

This is because researchers can determine what animal or plant species existed during a given window in Earth’s evolutionary history by looking for bits of DNA in well-preserved samples that, in some cases, are hundreds of thousands of years old.

Once these samples are identified, scientists can match the genetic codes in the DNA with their closest modern counterparts to determine what type of animal or species they belong to. In this way, humanity can form a picture of entire ecosystems 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 lifespan of a DNA molecule. Once cells begin to die, enzymes get to work breaking down the bonds that hold these vital molecules together. Under normal conditions in animals, this putrefactive process will render DNA useless in about 521 years.

However, when DNA can be stored quickly and stably under the right conditions, samples are known to survive much longer.

The sediment was eventually preserved in ice or permafrost and, crucially, undisturbed by humans for two million years

In the new study, scientists were able to recover 41 ancient DNA samples from the mouth of a fjord 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 København Formation — was only a few millionths of a millimeter long and encased in a protective shell of clay and quartz.

Using a combination of radiocarbon and molecular dating techniques, the international team of more than 40 scientists estimated that the DNA was on average about 2 million years old. This makes them 1 million years older than the previous record holder for ancient DNA, which was recovered from the bone of a Siberian mammoth.

“The ancient DNA samples were found buried deep in sediment that had built up over 20,000 years,” says Professor Kurt Kjær from the University of Copenhagen, who helped lead the research. “The sediment was ultimately preserved in ice or permafrost and, crucially, not disturbed by humans for two million years.”

After painstakingly comparing the DNA to 21st century data, the team was able to decode the fingerprints of a thriving ancient ecosystem locked inside the samples.

When the København Formation formed about two million years ago, Greenland was a more hospitable place, with temperatures about 10 – 17 degrees Celsius higher than today.

The DNA evidence revealed the presence of numerous plant species in the ancient environment, including forms of poplar and birch. Lemmings, reindeer, hares and even giant elephant-like creatures called Mastadon are said to have roamed among these trees. There were also DNA fragments that could not be compared with any modern animal or plant.

Many of the samples have been awaiting analysis since they were first collected at the Greenland site in 2006.

“It was only when a new generation of DNA extraction and sequencing equipment was developed that we were able to locate and identify extremely small and damaged DNA fragments in the sediment samples,” explains Professor Kjær. “It meant we were finally able to map a two-million-year-old ecosystem.”

The data suggests that more species may evolve and adapt to wildly varying temperatures than previously thought

The scientists behind the new study believe that the relatively warm environment of ancient Greenland is similar to the temperatures we could see in the future due to global warming. Modern day climate change is considered a serious threat to global biodiversity, and the speed at which species can adapt to changing environments and warming temperatures will be critical to their survival.

“The data suggest that more species may evolve and adapt to wildly varying temperatures than previously thought,” said assistant professor Mikkel Pedersen of the Lundbeck Foundation’s GeoGenetics Center, co-first author of the new paper. “But, crucially, these results show that they need time to do this.”

It is hoped that by analyzing the DNA of ancient trees and plants, the scientists can unravel the secrets of how they have adapted to their hot environment, and possibly learn how to make endangered species more resilient to climate change today. .

Looking ahead, the team hopes to uncover more examples of truly ancient DNA in clay from Africa that could shed light on humanity’s earliest 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 in cutting-edge developments in multiple scientific fields and has absolutely no time for your jokes. Follow him on Twitter @BeardConGamer

Image credit: Beth Zaiken

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