2022年12月11日 VOA慢速英语：科学家研究已知最古老的 DNA

 


Scientists discovered the oldest known DNA and used it to study what life was like 2 million years ago in Greenland.
科学家发现了已知最古老的 DNA，并用它来研究 200 万年前格陵兰岛的生活情况。
 
Today, northern Greenland is an empty, cold area. But in the past, it was full of trees, plants, and animals.
今天，格陵兰岛北部是一个空旷、寒冷的地区。但在过去，这里到处都是树木、植物和动物。
 
Kurt 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."
哥本哈根大学的 Kurt Kjær 是这项研究的主要作者。他说这项研究“打开了一扇通向基本上已经丢失的过去的大门”。
 
For 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.
在这项研究中，研究人员检查了土壤样本中的环境 DNA，也称为 eDNA。 eDNA 是生物体放入周围环境（包括毛发和排泄物）中的遗传物质。
 
The 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.
古代 DNA 的问题在于，遗传物质会随着时间的推移而分解，留给科学家的研究片段非常小。但是，剑桥大学的 Eske Willerslev 表示，借助最新技术，研究人员能够从受损的小 DNA 片段中获取遗传信息。
 
In the study, which appeared recently in the publication Nature, researchers compared the DNA to that of different species, looking for matches.
在最近发表在出版物中的这项研究中自然，研究人员将 DNA 与不同物种的 DNA 进行比较，寻找匹配项。
 
The 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.
样本来自皮里兰的一个地区，那里现在是一个寒冷、空旷的地方。但数百万年前，该地区经历了一段剧烈的气候变化时期，导致气温大幅上升，Willerslev 说。
 
Soil 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.
土壤和岩石可能在该地区积累了数万年气候变冷并将 DNA 锁在永久冻土中。从 2006 年开始，寒冷的环境帮助保存了小块 DNA，直到科学家们出现并取出样本。
 
The 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.
研究人员表示，当平均气温比今天高 11 至 19 摄氏度时，该地区的植物和动物数量异常多。 DNA 片段表明北极植物与通常生长在温暖气候下的植物混合存在。
 
The 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.
DNA 还显示存在动物，包括鹅、野兔、驯鹿和旅鼠。 Willerslev 说，以前，一只蜣螂和一些野兔遗骸是该地区唯一的动物生命迹象。
 
The 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.
研究人员说，一个巨大的惊喜是从乳齿象中发现了 DNA，这是一种看起来很古老的物种就像大象和猛犸象的混合体。以前曾在距格陵兰岛很远的北美森林中发现乳齿象 DNA 遗骸。
 
"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.
“我不会期望在一百万年内在格陵兰岛北部找到乳齿象，”说喜欢达伦。达伦是斯德哥尔摩大学的研究员，他没有参与这项研究。
 
DNA 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.
DNA 样本还表明该地区存在鲎和绿藻。 Kjær 解释说附近的水域很可能
 
Laura 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.
Laura Epp 没有参与这项研究，她是德国康斯坦茨大学的 eDNA 专家。她说，根据现有数据，很难确定这些物种是否比邻而居，或者 DNA 是否从景观的不同部分混合在一起。但 Epp 说，这种 DNA 研究对于揭示古代景观中的“隐藏多样性”很有价值。
 
Willerslev 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.
Willerslev 认为，由于这些植物和动物在极端气候变化时期幸存下来，它们的 DNA 可以提供一个帮助我们应对当前变暖的“遗传路线图”。
 
Stockholm University's Dalen expects ancient DNA research to keep pushing deeper into the past.
斯德哥尔摩大学的 Dalen 预计古代 DNA 研究将继续深入到过去。
 
"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.
“我不会感到惊讶如果你能回到至少一年或几百万年前，假设你能找到合适的样本