评论
打印
The researchers were surprised by some of the species they found.
研究人员对他们发现的一些物种感到惊讶。
Caribou live today in Greenland, as they do across much of the Arctic.
今天，驯鹿生活在格陵兰岛，就像它们生活在北极大部分地区一样。
But until now, their fossil record suggested they evolved a million years ago.
但到目前为止，他们的化石记录表明，它们是在100万年前进化的。
Their DNA now doubles their evolutionary history.
他们的DNA现在使他们的进化史翻倍。
Love Dalén, a paleogeneticist from Stockholm University who last year discovered mammoth DNA in Siberia that was 1.2 million years old, marveled that mastodons turned up in Greenland.
斯德哥尔摩大学的古遗传学家勒夫·达伦去年在西伯利亚发现了120万年前的猛犸象DNA，他对格陵兰岛出现乳齿象感到惊讶。
“What the hell are they doing up there?” he asked.
“它们到底在那里干什么？”他问道。
Dr. Dalén noted that the nearest known mastodon fossils were 75,000-year-old remains in Nova Scotia — which are far younger than the Greenland DNA, and much farther south than Kap Kobenhavn.
达伦博士指出，已知最新的乳齿象化石是新斯科舍省7.5万年前的遗骸——比格陵兰的DNA年轻得多，远比Kap Kobenhavn的位置偏南。
“You can’t go much further north on dry land,” he said.
“在干燥的陆地上，你不能再往北走了。”他说。
The Danish researchers determined that the mastodons in Greenland two million years ago belonged to a deep branch of the mastodon family tree, one that was previously unknown.
丹麦研究人员确定，200万年前格陵兰岛的乳齿象属于乳齿象家族树的一个深分支，这在以前是未知的。
“That could mean they are the ancestors of the late-Pleistocene mastodons that we know of, or that they could represent a new species,” Dr. Dalén said.
“这可能意味着它们是我们所知的晚更新世乳齿象的祖先，或者它们可能代表了一个新的物种。”达伦博士说。
Ecologically, mastodons would fit in well in a poplar-birch forest in Greenland, as they did in North American woodlands.
从生态上讲，乳齿象很适合格陵兰岛的白杨-白桦森林，就像它们很好地适应北美的林地一样。
While caribou are most common on northern tundras, a subspecies lives in Canadian forests, offering clues to how the ancient caribou might have thrived.
虽然北美驯鹿在北部苔原上最常见，但加拿大森林中生活着一个亚种，这为古代驯鹿是如何繁衍生息提供了线索。
But the presence of horseshoe crabs in the shallow coastal waters suggests that the ocean and land alike were remarkably warm.
但在沿海浅水区发现的马蹄蟹表明，海洋和陆地都非常温暖。
Dr. Willerslev and his colleagues are continuing to study the DNA for clues to how all these species were able to thrive a thousand miles north of the Arctic Circle.
威勒斯列夫博士和他的同事们正在继续研究DNA，以寻找所有这些物种在北极圈以北一千英里处繁衍生息的线索。
The trees, for example, had to survive half the year in darkness.
例如，这些树木必须在黑暗中存活半年。
The DNA preserved for two million years may hold their secrets of adaptation.
保存了两百万年的DNA可能隐藏着它们适应环境的秘密。
The scientists are also interested in how the DNA fragments managed to survive so long and defy expectations.
科学家们还感兴趣的是，这些DNA片段是如何存活这么长时间并超出人们的预期。
Their research indicates that the DNA molecules can cling to minerals of feldspar and clay, which protect them from further damage.
他们的研究表明，DNA分子可以附着在长石和粘土等矿物上，保护它们免受进一步损害。
Based on that discovery, the researchers are developing new methods that they hope will let them pull even more DNA out of ancient sediments.
基于这一发现，研究人员正在开发新的方法，他们希望能从古代沉积物中提取更多的DNA。
Dr. Kjaer and his colleagues are scouting four-million-year-old sites in Canada with the hope of breaking their own record.
克亚博士和他的同事们正在侦查加拿大有400万年历史的遗址，希望打破他们自己的记录。
Dr. Dalén said they might succeed.
达伦博士说，他们可能会成功。
But the damage that both he and the Danish researchers are finding in the oldest DNA suggests to him that it will be impossible to find ancient genetic material older than about five million years.
但他和丹麦研究人员在最古老的DNA中发现的损伤表明，不可能找到超过500万年的古代遗传物质。
“This in no way suggests that there will be any DNA coming out of dinosaur-aged fossils,” he said.
“这绝不意味着恐龙时代的化石中会有DNA。”他说。
Dr. Christ said that finding more DNA may help them better understand how human-driven climate change will alter the Arctic.
克里斯特博士说，发现更多的DNA可能有助于他们更好地理解，人类驱动的气候变化将如何改变北极。
We should not assume, he said, that the region will resemble ecosystems in places farther south.
他说，我们不应该假设该地区会与更靠南的地方的生态系统相似。
After all, the ecosystem of Kap Kobenhavn two million years ago has no analog today.
毕竟，两百万年前的Kap Kobenhavn的生态系统与如今的任何生态系统都不相似。
“Life will adapt, but in ways we don’t expect,” Dr. Christ said.
“生命会适应环境，但以我们意想不到的方式，”克里斯特博士说。
