2022年12月11日 VOA慢速英語：科學(xué)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.
科學(xué)家發(fā)現(xiàn)了已知最古老的 DNA，并用它來研究 200 萬年前格陵蘭島的生活情況。
 
Today, northern Greenland is an empty, cold area. But in the past, it was full of trees, plants, and animals.
今天，格陵蘭島北部是一個空曠、寒冷的地區(qū)。但在過去，這里到處都是樹木、植物和動物。
 
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."
哥本哈根大學(xué)的 Kurt Kjær 是這項研究的主要作者。他說這項研究“打開了一扇通向基本上已經(jīng)丟失的過去的大門”。
 
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.
在這項研究中，研究人員檢查了土壤樣本中的環(huán)境 DNA，也稱為 eDNA。 eDNA 是生物體放入周圍環(huán)境（包括毛發(fā)和排泄物）中的遺傳物質(zhì)。
 
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 的問題在于，遺傳物質(zhì)會隨著時間的推移而分解，留給科學(xué)家的研究片段非常小。但是，劍橋大學(xué)的 Eske Willerslev 表示，借助最新技術(shù)，研究人員能夠從受損的小 DNA 片段中獲取遺傳信息。
 
In the study, which appeared recently in the publication Nature, researchers compared the DNA to that of different species, looking for matches.
在最近發(fā)表在出版物中的這項研究中自然，研究人員將 DNA 與不同物種的 DNA 進行比較，尋找匹配項。
 
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.
樣本來自皮里蘭的一個地區(qū)，那里現(xiàn)在是一個寒冷、空曠的地方。但數(shù)百萬年前，該地區(qū)經(jīng)歷了一段劇烈的氣候變化時期，導(dǎo)致氣溫大幅上升，Willerslev 說。
 
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.
土壤和巖石可能在該地區(qū)積累了數(shù)萬年氣候變冷并將 DNA 鎖在永久凍土中。從 2006 年開始，寒冷的環(huán)境幫助保存了小塊 DNA，直到科學(xué)家們出現(xiàn)并取出樣本。
 
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.
研究人員表示，當(dāng)平均氣溫比今天高 11 至 19 攝氏度時，該地區(qū)的植物和動物數(shù)量異常多。 DNA 片段表明北極植物與通常生長在溫暖氣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 還顯示存在動物，包括鵝、野兔、馴鹿和旅鼠。 Willerslev 說，以前，一只蜣螂和一些野兔遺骸是該地區(qū)唯一的動物生命跡象。
 
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.
研究人員說，一個巨大的驚喜是從乳齒象中發(fā)現(xiàn)了 DNA，這是一種看起來很古老的物種就像大象和猛犸象的混合體。以前曾在距格陵蘭島很遠的北美森林中發(fā)現(xiàn)乳齒象 DNA 遺骸。
 
"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.
“我不會期望在一百萬年內(nèi)在格陵蘭島北部找到乳齒象，”說喜歡達倫。達倫是斯德哥爾摩大學(xué)的研究員，他沒有參與這項研究。
 
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 樣本還表明該地區(qū)存在鱟和綠藻。 Kjær 解釋說附近的水域很可能
 
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 沒有參與這項研究，她是德國康斯坦茨大學(xué)的 eDNA 專家。她說，根據(jù)現(xiàn)有數(shù)據(jù)，很難確定這些物種是否比鄰而居，或者 DNA 是否從景觀的不同部分混合在一起。但 Epp 說，這種 DNA 研究對于揭示古代景觀中的“隱藏多樣性”很有價值。
 
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 認為，由于這些植物和動物在極端氣候變化時期幸存下來，它們的 DNA 可以提供一個幫助我們應(yīng)對當(dāng)前變暖的“遺傳路線圖”。
 
Stockholm University's Dalen expects ancient DNA research to keep pushing deeper into the past.
斯德哥爾摩大學(xué)的 Dalen 預(yù)計古代 DNA 研究將繼續(xù)深入到過去。
 
"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.
“我不會感到驚訝如果你能回到至少一年或幾百萬年前，假設(shè)你能找到合適的樣本