Scientists have identified the oldest DNA ever discovered, and in the process revealed a complex ecosystem that existed two million years ago in modern-day Greenland. Nature🇧🇷
The double-helical molecule deoxyribonucleic acid (or DNA for short) is present in almost every cell of our human body and in the cells of plants and animals that live on our planet.
Each DNA molecule contains the genetic code unique to each individual and serves as a vital instruction manual for our cells that help control how our bodies develop and function. It is also an incredibly useful molecule for scientists looking to decipher the mysteries of the ancient past.
This is because researchers can determine which animal or plant species were present during a particular window of Earth’s evolutionary history by looking for fragments of DNA in well-preserved specimens, sometimes dating back hundreds of thousands of years.
Once these patterns are identified, scientists can match the genetic code found in the DNA with their closest modern counterparts to determine what type of animal or species they belong to. In this way, humanity can build a picture of all the ecosystems lost to the inexorable 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. As cells begin to die, enzymes go to work to break down the bonds that hold these vital molecules together. Under normal conditions in animals, this decay process will render the DNA useless after about 521 years.
However, when the right conditions allow DNA to be preserved quickly and stably, samples have been found to survive much longer.
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In a new study, scientists were able to extract 41 ancient DNA samples from the mouth of a fjord at the northernmost point of Greenland, where the land 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, an international team of more than 40 scientists was able to estimate that the DNA was about 2 million years old on average. This makes them 1 million years older than the previous record holder for ancient DNA, found in the bone of a Siberian mammoth.
“Ancient DNA Samples Found Deep in Sediments Over 20,000 Years Old” Commentary Professor Kurt Kjær professor at the University of Copenhagen, who helped lead the study. “The sediment was eventually preserved in ice or permafrost and, crucially, was undisturbed by humans for two million years.”
After painstakingly comparing the DNA with 21st-century data, the team was able to decipher the fingerprints of a thriving, ancient ecosystem locked within the samples.
Around two million years ago, when the København Formation formed, Greenland was a more hospitable place, with temperatures about 10 to 17 degrees Celsius warmer than today.
DNA evidence has revealed the presence of a myriad of plant life in the ancient environment, including forms of poplar and birch. Among these trees roamed lemmings, reindeer, rabbits and even a giant elephant creature called Mastadon. There were also pieces of DNA that could not be matched with any animal or plant in our modern era.
Many of the samples have been awaiting analysis since they were first collected from Greenland in 2006.
Professor Kjær explained: “It was only until the next generation of DNA extraction and sequencing equipment was developed that we were able to find and identify very small and damaged DNA fragments in sediment samples. can map a two-million-year-old ecosystem.”
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The scientists behind the new study believe the relatively warm climate of ancient Greenland is comparable to the temperatures we may see in the future as a result of global warming. modern day climate change is considered a serious threat to biodiversity globally, and the speed with which species can adapt to changing environments and warming temperatures will be key to their survival.
“The data show that more species can evolve and adapt to wildly varying temperatures than previously thought,” said Mikkel Pedersen, assistant professor at the Lundbeck Foundation’s Center for GeoGenetics and first author of the new paper. “But importantly, these results show that it takes time to do that.”
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 warmer environments and potentially learn how to make endangered species more resilient to climate change. .
Moving forward, the team hopes to discover truly ancient DNA samples 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 covering events in many scientific fields, and you don’t have time for ambition. Follow him on Twitter @BeardConGamer
Photo credit: Beth Zaiken
