Scientists Study Oldest-known DNA
2022-12-11
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1Scientists discovered the oldest known DNA and used it to study what life was like 2 million years ago in Greenland.
2Today, northern Greenland is an empty, cold area.
3But in the past, it was full of trees, plants, and animals.
4Kurt Kjær of the University of Copenhagen was the study's lead writer.
5He said the research "opens the door into a past that has basically been lost."
6For the study, researchers examined environmental DNA, also known as eDNA, from soil samples.
7eDNA is the genetic material that organisms put into their surroundings, including hair and waste.
8The problem with ancient DNA is that the genetic material breaks down over time, leaving scientists with very small pieces to study.
9But, with the latest technology, Eske Willerslev of the University of Cambridge said researchers were able to get genetic information out of the small, damaged pieces of DNA.
10In the study, which appeared recently in the publication Nature, researchers compared the DNA to that of different species, looking for matches.
11The samples came from an area in Peary Land, which is now a cold, empty place.
12But millions of years ago, the area went through a time of strong climate change that sent temperatures way up, Willerslev said.
13Soil and rocks likely built up for tens of thousands of years in the area before the climate cooled and locked the DNA into permafrost.
14The cold environment helped save the small pieces of DNA - until scientists came along and took the samples out, beginning in 2006.
15The researchers said when average temperatures were 11 to 19 degrees Celsius higher than today, the area had an unusual number of plant and animal life.
16And pieces of DNA suggest a mix of Arctic plants with ones that usually grow in warmer climates.
17The DNA also showed the presence of animals including geese, hares, reindeer and lemmings.
18Previously, a dung beetle and some hare remains had been the only signs of animal life in the area, Willerslev said.
19The researchers said one big surprise was finding DNA from the mastodon, an ancient species that looked like a mix between an elephant and a mammoth.
20Mastodon DNA remains have previously been found in forests in North America, a long way away from Greenland.
21"I wouldn't have, in a million years, expected to find mastodons in northern Greenland," said Love Dalen.
22Dalen, who was not involved in the study, is a researcher at Stockholm University.
23DNA samples also suggest the presence of horseshoe crabs and green algae in the area.
24Kjær explained that nearby waters were likely much warmer back then.
25Laura Epp, who was not involved in the study, is an eDNA expert at Germany's University of Konstanz.
26She said, with the available data, it is hard to say for sure whether these species lived side by side, or if the DNA was mixed together from different parts of the landscape.
27But Epp said this kind of DNA research is valuable to show "hidden diversity" in ancient landscapes.
28Willerslev believes that because these plants and animals survived during a time of extreme climate change,
29their DNA could offer a "genetic roadmap" to help us deal with current warming.
30Stockholm University's Dalen expects ancient DNA research to keep pushing deeper into the past.
31"I wouldn't be surprised if you can go at least one or perhaps a few million years further back, assuming you can find the right samples," Dalen said.
32I'm John Russell.
1Scientists discovered the oldest known DNA and used it to study what life was like 2 million years ago in Greenland. 2Today, northern Greenland is an empty, cold area. But in the past, it was full of trees, plants, and animals. 3Kurt Kjær of the University of Copenhagen was the study's lead writer. He said the research "opens the door into a past that has basically been lost." 4For the study, researchers examined environmental DNA, also known as eDNA, from soil samples. eDNA is the genetic material that organisms put into their surroundings, including hair and waste. 5The problem with ancient DNA is that the genetic material breaks down over time, leaving scientists with very small pieces to study. But, with the latest technology, Eske Willerslev of the University of Cambridge said researchers were able to get genetic information out of the small, damaged pieces of DNA. 6In the study, which appeared recently in the publication Nature, researchers compared the DNA to that of different species, looking for matches. 7The samples came from an area in Peary Land, which is now a cold, empty place. But millions of years ago, the area went through a time of strong climate change that sent temperatures way up, Willerslev said. 8Soil and rocks likely built up for tens of thousands of years in the area before the climate cooled and locked the DNA into permafrost. The cold environment helped save the small pieces of DNA - until scientists came along and took the samples out, beginning in 2006. 9The researchers said when average temperatures were 11 to 19 degrees Celsius higher than today, the area had an unusual number of plant and animal life. And pieces of DNA suggest a mix of Arctic plants with ones that usually grow in warmer climates. 10The DNA also showed the presence of animals including geese, hares, reindeer and lemmings. Previously, a dung beetle and some hare remains had been the only signs of animal life in the area, Willerslev said. 11The researchers said one big surprise was finding DNA from the mastodon, an ancient species that looked like a mix between an elephant and a mammoth. Mastodon DNA remains have previously been found in forests in North America, a long way away from Greenland. 12"I wouldn't have, in a million years, expected to find mastodons in northern Greenland," said Love Dalen. Dalen, who was not involved in the study, is a researcher at Stockholm University. 13DNA samples also suggest the presence of horseshoe crabs and green algae in the area. Kjær explained that nearby waters were likely much warmer back then. 14Laura Epp, who was not involved in the study, is an eDNA expert at Germany's University of Konstanz. She said, with the available data, it is hard to say for sure whether these species lived side by side, or if the DNA was mixed together from different parts of the landscape. But Epp said this kind of DNA research is valuable to show "hidden diversity" in ancient landscapes. 15Willerslev believes that because these plants and animals survived during a time of extreme climate change, their DNA could offer a "genetic roadmap" to help us deal with current warming. 16Stockholm University's Dalen expects ancient DNA research to keep pushing deeper into the past. 17"I wouldn't be surprised if you can go at least one or perhaps a few million years further back, assuming you can find the right samples," Dalen said. 18I'm John Russell. 19Maddie Burakoff reported on this story for the Associated Press. John Russell adapted it for VOA Learning English. 20_________________________________________________________________ 21Words in This Story 22DNA - n. a substance that carries genetic information in the cells of plants and animals - often used before another noun 23basically -- adv. in a general or basic way - used to say that something is true or correct as a general statement even if it is not entirely true or correct 24sample - n. a small amount of something that gives you information about the thing it was taken from 25species -- n. biology : a group of animals or plants that are similar and can produce young animals or plants : a group of related animals or plants that is smaller than a genus 26permafrost - n. a layer of soil that is always frozen in very cold regions of the world 27mammoth - n. a type of large, hairy elephant that lived in ancient times and that had very long tusks that curved upward 28landscape -- n. an area of land that has a particular quality or appearance 29assume -- v. to think that something is true or probably true without knowing that it is true