(单词翻译:单击)
Oldest Known DNA Offers Glimpse of a Once-Lush Arctic
从已知最古老的DNA中窥见曾经郁郁葱葱的北极
In the permafrost at the northern edge of Greenland, scientists have discovered the oldest known fragments of DNA, offering an extraordinary look at an extraordinary ancient ecosystem.
在格陵兰岛北部边缘的永久冻土中，科学家们发现了已知最古老的DNA片段，让人们难得看到了一个不同寻常的古代生态系统。
The genetic material dates back at least two million years -- that's nearly twice as old as the mammoth DNA in Siberia that held the previous record.
这种遗传物质至少可以追溯到200万年前----比此前纪录保持者西伯利亚猛犸象的DNA要古老一倍。
And the samples, described on Wednesday in the journal Nature, came from more than 135 different species. Together, they show that a region just 600 miles from the North Pole was once covered by a forest of poplar and birch trees inhabited by mastodons.
这些样本来自超过135个不同的物种，在周三的《自然》期刊上进行了描述。它们共同表明，距离北极仅600英里的一个地区曾经被白杨树和桦树森林所覆盖，这里也曾是乳齿象的栖息地。
The forests were also home to caribou and Arctic hares. And the warm coastal waters were filled with horseshoe crabs, a species that today cannot be found any farther north of Maine. Independent experts hailed the study as a major advance.
这些森林也是驯鹿和北极野兔的家园。温暖的沿海水域充满了马蹄蟹，这一物种如今在缅因州以北的地方已难寻踪迹。独立专家称赞这项研究是一项重大进步。
"It feels almost magical to be able to infer such a complete picture of an ancient ecosystem from tiny fragments of preserved DNA," said Beth Shapiro, a paleogeneticist at the University of California, Santa Cruz.
"从保存下来的DNA微小片段中推断出一个古老生态系统的完整图景，这让人感觉很神奇。"加州大学圣克鲁斯分校的古遗传学家贝丝·夏皮罗说。
"I think it's going to blow people's minds," said Andrew Christ, a geoscientist at the University of Vermont who studies the ancient Arctic. "It certainly did so for me."
"我认为这会让人们大为震惊。"佛蒙特大学研究古代北极的地球科学家安德鲁·克罗斯说，"反正已经让我感到吃惊了。"
The discovery came after two decades of scientific gambles and frustrating setbacks.
这一发现是历经了二十年的科学赌博和令人沮丧的挫折之后取得的。
One of the leaders of the project, Eske Willerslev, pioneered methods for pulling DNA out of sediment while he was a graduate student at the University of Copenhagen.
该项目的领导者之一埃斯克·威勒斯列夫在哥本哈根大学读研究生时，就开创了从沉积物中提取DNA的方法。
In 2003, studying a chunk of Siberian permafrost, he and his colleagues found DNA from plants such as willow and daisies dating 400,000 years ago. That discovery set a record for the oldest DNA, and many scientists doubted it would be possible to find anything much older.
2003年，在研究西伯利亚的一大块永久冻土时，他和同事们发现了40万年前柳树和雏菊等植物的DNA。这一发现创造了最古老的DNA纪录，许多科学家怀疑是否有可能发现更古老的东西。
But in 2006, Dr. Willerslev and Kurt Kjaer, a geoscientist at the University of Copenhagen, tried to defy the odds in northern Greenland.
但在2006年，威勒斯列夫博士和哥本哈根大学的地球科学家库尔特·克亚，试图在格陵兰岛北部挑战这种可能性。
They made their way to a geological formation called Kap Kobenhavn, a series of bare hills as desolate as a moonscape. Previously, scientists had found plant fossils there that they estimated to be 2.4 million years old.
他们来到了一个名为Kap Kobenhavn的地质构造，这是一些如月球表面般荒凉的光秃秃的小山。此前，科学家在那里发现了植物化石，他们估计这些化石有240万年的历史。
Finding DNA in the sediments would have been astonishing. "If you want to move things forward, you need to take some leaps," Dr. Kjaer said.
在这些沉积物中发现DNA将是令人震惊的。"如果想让事情向前发展，那就需要跳几步。"克亚博士说。
The researchers dug up permafrost and brought it back to Copenhagen to search for DNA. They failed to find any. In later years, Dr. Willerslev and his colleagues had more success when they examined younger sediments and bones from other parts of the world.
研究人员挖出了永久冻土，并将其带回哥本哈根寻找DNA。他们一无所获。在后来的几年里，威勒斯列夫博士和他的同事们在研究世界其他地区较为晚期的沉积物和骨骼时取得了更大的成功。
They discovered a wealth of ancient human DNA that has helped reshape our understanding of our species' history.
他们发现了丰富的古人类DNA，帮助我们重塑了对人类历史的理解。
