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Scientists Study Oldest-known DNA

时间:2022-12-15 02:35:51

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Scientists Study Oldest-known DNA1

Scientists discovered the oldest known DNA and used it to study what life was like 2 million years ago in Greenland.

Today, northern Greenland is an empty, cold area. But in the past, it was full of trees, plants, and animals.

Kurt Kjaer 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."

For the study, researchers examined environmental DNA, also known as eDNA, from soil samples. eDNA is the genetic2 material that organisms put into their surroundings, including hair and waste.

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.

In the study, which appeared recently in the publication Nature, researchers compared the DNA to that of different species, looking for matches.

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.

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.

The researchers said when average temperatures were 11 to 19 degrees Celsius3 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.

The DNA also showed the presence of animals including geese, hares, reindeer4 and lemmings. Previously5, a dung beetle6 and some hare remains7 had been the only signs of animal life in the area, Willerslev said.

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 mammoth8. Mastodon DNA remains have previously been found in forests in North America, a long way away from Greenland.

"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.

DNA samples also suggest the presence of horseshoe crabs9 and green algae10 in the area. Kjaer explained that nearby waters were likely much warmer back then.

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.

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.

Stockholm University's Dalen expects ancient DNA research to keep pushing deeper into the past.

"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.

Words in This Story

DNA – n. a substance that carries genetic information in the cells of plants and animals — often used before another noun

basically -- 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 entirely11 true or correct

sample – n. a small amount of something that gives you information about the thing it was taken from

species -- 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

permafrost – n. a layer of soil that is always frozen in very cold regions of the world

mammoth – n. a type of large, hairy elephant that lived in ancient times and that had very long tusks12 that curved upward

landscape -- n. an area of land that has a particular quality or appearance

assume -- v. to think that something is true or probably true without knowing that it is true


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1 DNA 4u3z1l     
(缩)deoxyribonucleic acid 脱氧核糖核酸
参考例句:
  • DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
  • Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。
2 genetic PgIxp     
adj.遗传的,遗传学的
参考例句:
  • It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
  • Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。
3 Celsius AXRzl     
adj.摄氏温度计的,摄氏的
参考例句:
  • The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
  • The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。
4 reindeer WBfzw     
n.驯鹿
参考例句:
  • The herd of reindeer was being trailed by a pack of wolves.那群驯鹿被一只狼群寻踪追赶上来。
  • The life of the Reindeer men was a frontier life.驯鹿时代人的生活是一种边区生活。
5 previously bkzzzC     
adv.以前,先前(地)
参考例句:
  • The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • Let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
6 beetle QudzV     
n.甲虫,近视眼的人
参考例句:
  • A firefly is a type of beetle.萤火虫是一种甲虫。
  • He saw a shiny green beetle on a leaf.我看见树叶上有一只闪闪发光的绿色甲虫。
7 remains 1kMzTy     
n.剩余物,残留物;遗体,遗迹
参考例句:
  • He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
  • The remains of the meal were fed to the dog.残羹剩饭喂狗了。
8 mammoth u2wy8     
n.长毛象;adj.长毛象似的,巨大的
参考例句:
  • You can only undertake mammoth changes if the finances are there.资金到位的情况下方可进行重大变革。
  • Building the new railroad will be a mammoth job.修建那条新铁路将是一项巨大工程。
9 crabs a26cc3db05581d7cfc36d59943c77523     
n.蟹( crab的名词复数 );阴虱寄生病;蟹肉v.捕蟹( crab的第三人称单数 )
参考例句:
  • As we walked along the seashore we saw lots of tiny crabs. 我们在海岸上散步时看到很多小蟹。 来自《简明英汉词典》
  • The fish and crabs scavenge for decaying tissue. 鱼和蟹搜寻腐烂的组织为食。 来自《简明英汉词典》
10 algae tK6yW     
n.水藻,海藻
参考例句:
  • Most algae live in water.多数藻类生长在水中。
  • Algae grow and spread quickly in the lake.湖中水藻滋蔓。
11 entirely entirely     
ad.全部地,完整地;完全地,彻底地
参考例句:
  • The fire was entirely caused by their neglect of duty. 那场火灾完全是由于他们失职而引起的。
  • His life was entirely given up to the educational work. 他的一生统统献给了教育工作。
12 tusks d5d7831c760a0f8d3440bcb966006e8c     
n.(象等动物的)长牙( tusk的名词复数 );獠牙;尖形物;尖头
参考例句:
  • The elephants are poached for their tusks. 为获取象牙而偷猎大象。
  • Elephant tusks, monkey tails and salt were used in some parts of Africa. 非洲的一些地区则使用象牙、猴尾和盐。 来自英语晨读30分(高一)

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