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VOA慢速英语:俄罗斯的永久冻土提供了埋藏的宝藏

Source: 恒星英语学习网    2019-12-23   English BBS   Favorite  

Call it buried biological treasure.

大世界代理Remains of animals that lived thousands of years ago are being recovered from Russia's far north.

Russian researchers released images of an 18,000-year-old dog last month. The dog had many yellow teeth, and appeared to be young when it died.

Scientists named the ancient creature Dogor. But they cannot say whether it was closer genetically to modern dogs or wolves. They add that Dogor was alive during a period of time when human beings first appeared on Earth.

It is the latest buried treasure from Siberia — the traditionally frozen part of northern Russia. The icy climate has kept large stretches of land frozen for thousands of years.

大世界代理Now the deep freeze has eased as rising temperatures and other developments combine to bring these long buried secrets to light.

Russia's frozen underground — known as permafrost — covers nearly two-thirds of the nation's 17 million square kilometers. The permafrost protected the bodies of prehistoric animals — ones that walked before the end of Earth's last Ice Age.

For about 10 years, the permafrost has melted, broken down or is being dug up for people searching for valuable treasures like ivory.

What is turning up?

What is turning up?

Well-preserved woolly mammoths, woolly rhinoceros, dog-wolves, long-gone big cats and other biological wonders and surprises.

They are giving researchers a better idea of evolutionary and natural history. They provide behavioral, physical and genetic information that might have been lost without them.

Some of the biological material and frozen cells contain DNA, the carrier of genetic information. Now there is controversy over whether DNA from these animals could be used to clone — or bring back to life — creatures from long ago. The process would involve putting their DNA into living animals.

In at least one case, Siberia has provided the seeds of an experiment that returned plants to life after tens of thousands of years in a deep freeze.

The Siberian ice is disappearing, with warmer weather melting parts of the permafrost. This provides a gold mine to the scientists as they come across these well-preserved animals.

大世界代理In 2010, scientists discovered "Yuka," the best-preserved woolly mammoth ever found. She died almost 40,000 years ago. Yuka was young, between 6 and 12 years of age, when she died.

Cloning controversy

With each mammoth find, comes more controversy.
The discovery of such well-preserved biological material started the talk of an effort to use DNA from Yuka's remains, or that of another mammoth, to clone them. Many people believe cloning methods are developed enough to successfully bring back an extinct species like the woolly mammoth with complete DNA.

One problem has been that radiation from outside Earth's atmosphere most likely damaged any DNA and makes it unusable for cloning.
This year, however, researchers announced they had taken "less-damaged nucleus-like structures from the remains" of Yuka. They said they saw "signs of biological activities" in them after placing them into mouse cells capable of forming eggs.

"Our work provides a platform to evaluate the biological activities of nuclei in extinct animal species," they declared in a study大世界代理 published last March in the publication Scientific Reports.

Other prehistoric finds in recent years include:

•The first complete body of a young woolly rhino, including its hair, was found near a Siberian river in 2015. Named Sasha and nearly a meter tall and 2 meters long at just 7 months of age, she would be much taller than modern rhinoceros. Early estimates put the age of Sasha's remains at between 10,000 and 34,000 years old.
•The partial head of a woolly rhino was found in Germany in 2008. The creature lived nearly 500,000 years ago, making it Europe's oldest such find.
•A prehistoric young horse was found in 2018 in eastern Russia. The animal was thought to be about 2 months old when it died, some 40,000 years ago. Its internal organs, tail, and hooves are whole, and even eyelashes and nostril hairs are clearly recognizable. The extinct species is known as a Lena horse.The prospect of harvesting useful DNA from the animal was high. The famous South Korean cloning researcher, Hwang Woo-suk, was part of team that examined the horse earlier this year. Hwang supports cloning techniques to revive woolly mammoths. He reportedly took samples of biological fluids like blood from the horse.
•The head of an ancient subspecies of wolf was also found last year. Its fur, brain and other body parts were said to be the best-preserved of any specimen. Scientists said it is about 25 percent larger than many modern wolves. The ancient animals are thought to have died off in the past 10,000 years or so.
I'm Anne Ball.

大世界代理And I'm Bryan Lynn.

Andy Heil wrote this story for RFE/RL. Anne Ball adapted his story for Learning English. George Grow was the editor.

What do you think of this story? Write to us in the comments section below.


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