As a species with ever-shorter attention spans, it can be difficult to understand how long life has existed on Earth. However, try to understand this one: scientists have unearthed DNA fragments dating back to 1 million years ago.
Found beneath the floor of the Scotia Sea, north of Antarctica, these fragments of organic matter may be invaluable in tracing the region’s history – mapping what lived in the ocean and over what time period. .
technically called sedaADN – for sedimentary ancient DNA – the samples recovered are likely to prove useful in ongoing efforts to understand how climate change could affect Antarctica in the future.
“This includes by far the oldest authenticated navy sedaDNA to date,” says marine ecologist Linda Arbrecht from the University of Tasmania in Australia.
SedaDNA is found in many environments, including terrestrial caves and subarctic permafrost, which have produced sedaDNA dating back 400,000 and 650,000 years respectively.
Cold temperatures, low oxygen and a lack of UV radiation make polar marine environments like the Scotia Sea great places to sedaThe DNA remains intact, waiting for us to find it.
The recovered DNA was mined from the ocean floor in 2019 and went through a comprehensive contamination screening process to ensure the age markers embedded in the material were accurate.
Among other discoveries, the team discovered diatoms (single-celled organisms) dating back to 540,000 years ago. All of this helps inform our insight into how this part of the world has evolved over vast stretches of time.
The team was able to link the abundance of diatoms to warmer periods, the last of which in the Scotia Sea was around 14,500 years ago. This has led to an increase in the overall activity of marine life in the Antarctic region.
“This is an interesting and important change that is associated with a global and rapid rise in sea level and a massive loss of ice in Antarctica due to natural warming,” says geologist Michael Weber from the University. from Bonn in Germany.
This latest study proves that these sedaDNA techniques can be useful in reconstructing ecosystems over hundreds of thousands of years, giving us a whole new level of understanding of how the oceans have changed.
Scientists are steadily getting better at pulling these ancient DNA fragments out of the ground and removing the “noise” and interference left behind by all the modern DNA that has been around since to get an authentic look at the past.
A better understanding of past climate change and ocean ecosystem response means more accurate models and predictions for what might happen next around the South Pole.
“Antarctica is one of the most vulnerable regions to climate change on Earth, and there is an urgent need to study the past and present responses of this polar marine ecosystem to environmental change,” the researchers write in their published paper.
The research has been published in Nature Communication.
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