每日英語跟讀 Ep.K102: About Earth Science - World’s oldest DNA sequenced from million-year-old mammoths
Teeth from mammoths buried in the Siberian permafrost for more than a million years have yielded the world’s oldest DNA ever sequenced, according to a study published on Wednesday, shining the genetic searchlight into the deep past.
據週三公布的研究，埋在西伯利亞永凍土層超過100萬年的猛獁象牙齒，提供全球最古老的去氧核醣核酸（DNA）定序，讓基因研究的探照燈指向遙遠的過去。
Researchers said the three specimens, one roughly 800,000 years old and two over a million years old, provide important insights into the giant Ice Age mammals, including the ancient heritage of the woolly mammoth.
研究人員表示，這3個樣本，一個約有80萬年歷史，另2個來自超過100萬年前，為現代人瞭解冰河時代猛獁象，包括「真長毛象」（woolly mammoth）的古老傳承，提供重要觀察角度。
The genomes far exceed the oldest previously sequenced DNA － a horse dating between 780,000 to 560,000 years ago.
此前，最古老的DNA定序來自78萬年前到56萬年前的一匹馬，而這些猛獁象基因組的年代更久遠得多。
The mammoths were originally discovered in the 1970s in Siberia and held at the Russian Academy of Sciences in Moscow.
這幾頭猛獁象起初於1970年代在西伯利亞地區被發現，由莫斯科的俄羅斯科學院保管。
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Comet from edge of solar system killed the dinosaurs: study 研究：來自太陽系邊緣的彗星讓恐龍滅絕
Sixty-six million years ago, a huge celestial object struck off the coast of what is now Mexico, triggering a catastrophic "impact winter" that eventually wiped out three-quarters of life on Earth, including the dinosaurs.
6600萬年前，一個巨大星體撞上現在的墨西哥外海，引發釀成巨災的「衝擊性寒冬」，最後導致恐龍在內的地球上4分之3物種滅絕。
A pair of astronomers at Harvard say they have now resolved long standing mysteries surrounding the nature and origin of the "Chicxulub impactor."
哈佛大學2位天文學家表示，他們已經解開長久以來關於「希克蘇魯伯衝擊體」（Chicxulub impactor）的本質和來源之謎。
Their analysis suggests it was a comet that originated in a region of icy debris on the edge of the solar system, that Jupiter was responsible for it crashing into our planet, and that we can expect similar impacts every 250 million to 750 million years.
他們的分析顯示，這是源自太陽系邊緣冰冷碎片區域的一顆彗星，且木星也要為此彗星撞上地球負責。類似規模的彗星撞地球頻率為每2億5000萬年到7億5000萬年。
The duo’s paper, published in the journal Scientific Reports this week, pushes back against an older theory that claims the object was a fragment of an asteroid that came from our solar system’s Main Belt.
2人的論文本週在《科學報告》期刊發表，推翻了之前認為這個物體是來自太陽系「主小行星帶」小行星碎片的理論。
Source article: https://features.ltn.com.tw/english/article/paper/1435663 ; https://features.ltn.com.tw/english/article/paper/1437161
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