Scientists have found the oldest DNA sequence and in the process revealed a complex ecosystem that existed two million years ago in present-day Greenland, according to the results of a new study published in the journal Nature.
The double helix shapeless molecule Deoxyribonucleic Acid (or DNA for short) is present in almost every cell of our human bodies, and the plants and animals that inhabit our planet.
Each DNA molecule contains the genetic code unique to each individual, and serves as a vital instruction manual for cells that control how our bodies develop and function. It is also an incredibly useful molecule for scientists looking to unravel the secrets of the ancient past.
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This is because researchers can determine which species of animal or plant existed during a given window in Earth’s evolutionary history by looking for fragments of DNA in well-preserved samples, which in some cases date back hundreds of thousands of years.
By identifying these samples, scientists can match the genetic codes found in the DNA with their modern-day counterparts to determine what type of animal or species they belong to. In this way, humanity can create a picture of the entire ecosystem, which has been lost to the inexorable passage of time, and can gain valuable insights into the evolution of life on our planet.
Unfortunately, this technique is limited by the life span of the DNA molecule. When cells begin to die, enzymes get to work loosening the bonds that hold vital molecules together. Under normal conditions in animals, a defective process will render the DNA useless in some 521 years.
However, when the right conditions allow DNA to be stored quickly and stably, samples are known to survive much longer.
In a new study, scientists were able to recover 41 samples of ancient DNA from the mouth of a fjord located at the northernmost point of Greenland, where land meets the Arctic Ocean. The individual DNA samples extracted from the rock — known as the København Formation — were a few million miles long, and were enclosed in a safe shell of clay and quartz.
By applying a combination of radiocarbon dating and molecular technology, an international team of more than 40 scientists were able to estimate the DNA to be 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 a Siberian mammoth bone.
“Ancient DNA samples were found deep in sediment that had built up over 20,000 years ago,” comments Professor Kurt Kjær of the University of Copenhagen, who helped lead the research. “The pit was eventually preserved in ice or permafrost and, crucially, disturbed by humans for two million years.”
After carefully comparing the DNA with data from the 21st century, the team was able to decipher the fingerprints of a thriving, ancient ecosystem embedded within the samples.
At the time the København Formation was created two million years ago, Greenland was a more hospitable place, with temperatures roughly 10 – 17 degrees Celsius warmer than today.
DNA evidence has revealed the presence of countless species of plants in ancient life, including forms of humans and birch trees. Among these trees roamed lemmings, reindeer, hares, and even huge elephantine beasts called Mastadons. There were also DNA fragments that cannot be compared to any modern day animal or plant.
Many samples await analysis since they were first collected from the Greenland site in 2006.
“It wasn’t until a new type of DNA extraction and sequencing tool was developed that we were able to locate and visualize the smallest and most fragmented DNA particles in the sediment samples,” explained Professor Kjær. able to describe a two-million-year-old ecosystem. “
The scientists behind the new study believe that Greenland’s ancient, relatively warm environment could be compared to the temperatures we could see in the future as a result of global warming. Today’s climate change is considered a serious threat to biodiversity on a global scale, and species that can adapt to environmental changes and warming temperatures will be key to their survival.
“The data suggests that more species are evolving and adapting to different temperatures than previously thought,” said Assistant Professor Mikkel Pedersen of the Lundbeck Foundation’s GeoGenetics Center, co-first author of the new paper. “But, above all, these results show that it is time to do this.”
The hope is that by examining the DNA of ancient trees and plants, scientists will be able to unravel the mysteries of how they adapted to their warm environment, and potentially learn how endangered species are coping with today’s climate change. .
The advancing team hopes to discover more samples of really ancient DNA in clay from Africa, which could shed light on early human ancestors.
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Anthony is a freelance clothing science contributor and video game reporter for IGN. He has over eight years of experience in covering developments in multiple scientific fields and has absolutely no time for your shenanigans. Follow him on Twitter @BeardConGamer
Image Credit: Beth Zaiken
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