與尼安德塔人混血的早期現代人

原文網址：http://www.sciencedaily.com/releases/2015/06/150622122718.htm

Early modern humans interbred with Neanderthals

An early European had a close Neanderthal ancestor

與尼安德塔人混血的早期現代人

一位擁有尼安德塔近祖的早期歐洲人

Neanderthals became extinct about 40,000 years ago but contributed on average one to three percent to the genomes of present-day Eurasians. Researchers have now analyzed DNA from a 37,000 to 42,000-year-old human mandible from Oase Cave in Romania and have found that six to nine percent of this person's genome came from Neanderthals, more than any other human sequenced to date. Because large segments of this individual's chromosomes are of Neanderthal origin, a Neanderthal was among his ancestors as recently as four to six generations back in his family tree. This shows that some of the first modern humans that came to Europe mixed with the local Neanderthals.

雖然尼安德塔人在40,000年前就已經滅絕，但平均而言，現代歐洲人基因組的1%至3%來自於他們。研究人員分析發現於羅馬尼亞的Oase洞，年代約37,000至42,000年前的人類下顎骨中的DNA，發現此人的基因組中有6%至9%來自於尼安德塔人，比現今所有定序過的人類DNA都要多。由於他有來源為尼安德塔人的大片段染色體，因此觀其族譜，可能他的前4代至前6代祖先中就有一位是尼安德塔人。這顯示前往歐洲的第一批現代人類中，有一些曾與尼安德塔人通婚。

All present-day humans who have their roots outside sub-Saharan Africa carry one to three percent of Neanderthal DNA in their genomes. Until now, researchers have thought it most likely that early humans coming from Africa mixed with Neanderthals in the Middle East around 50,000 to 60,000 years ago, before spreading into Asia, Europe and the rest of the world. However, radiocarbon dating of remains from sites across Europe suggests that modern humans and Neanderthals both lived in Europe for up to 5,000 years and that they may have interbred there, too.

在所有祖先可以追溯至撒哈拉以南非洲之外的現代人來說，他們的基因組中會攜帶1%至3%來自尼安德塔人的DNA。目前為止，研究人員認為離開非洲的早期人類約在50,000至60,000年前，在中東與尼安德塔人混血，爾後才散佈至亞洲、歐洲與世界其他角落。然而，歐洲各地遺址中的骨骸的放射性碳定年結果顯示，現代人與尼安德塔人曾在歐洲共同生活達5,000年之久，因此他們也可能在歐洲混血。

In 2002, a 40,000-year-old jawbone was found by cavers in Oase Cave in south-western Romania and the site was subsequently studied by an international team led by the researchers of the Emil Racovita Institute of Speleology in Romania. Researchers from the Max Planck Institute for Evolutionary Anthropology (Germany), Harvard Medical School (USA), and the Key Laboratory of Vertebrate Evolution and Human Origins in Beijing (China) have now analyzed DNA from this fossil, which is one of the earliest modern-human remains found in Europe. They estimate that five to 11 percent of the genome preserved in the bone derives from a Neanderthal ancestor, including exceptionally large segments of some chromosomes. By estimating how lengths of DNA inherited from an ancestor shorten with each generation, the researchers estimated that the man had a Neanderthal ancestor in the previous four to six generations.

2002年，一些洞穴探索者在羅馬尼亞西南方的Oase洞發現一塊年代為40,000年的下顎骨，此遺址隨後由羅馬尼亞的埃米爾·拉科維澤洞穴學研究所(the Emil Racovita Institute of Speleology)的科學家所領導的國際團隊進行相關研究。馬克斯·普朗克演化人類學研究所(the Max Planck Institute for Evolutionary Anthropology，德國)、哈佛醫學院(Harvard Medical School，美國)與北京脊椎動物演化與人類起源重點實驗室(中國)的研究人員已完成這塊骨骸的DNA分析，其為在歐洲發現的現代人化石中，年代最古老的其中之一。他們估計這塊骨頭保存下來的基因組中有5%至11%來自他的一位尼安德塔人祖先，包括某些染色體中特別長的片段。藉由估算祖先留下來的DNA長度會如何隨著世代傳遞而縮減，研究人員估計這位男士的前4至6代中有一位尼安德塔人祖宗。

"The data from the jawbone imply that humans mixed with Neanderthals not just in the Middle East but in Europe as well" says Qiaomei Fu, one of the lead researchers of the study. "Interestingly, the Oase individual does not seem to have any direct descendants in Europe today," says David Reich from Harvard Medical School who coordinated the population genetic analyses of the study. "It may be that he was part of an early migration of modern humans to Europe that interacted closely with Neanderthals but eventually became extinct."

「從這塊下顎骨中得到的資料顯示，人類與尼安德塔人的混血不僅發生於中東，也會在歐洲發生。」其中一位主要研究人員付巧梅說。「有趣的是，在今日的歐洲似乎沒有這位Oase人的直系後裔。」來自哈佛醫學院，協助本研究的族群遺傳分析(population genetic analyse)的David Reich說。「他可能是早期移民至歐洲的現代人中，與尼安德塔人密切互動，但最終滅絕的族群中的其中一份子。」

"It is such a lucky and unexpected thing to get DNA from a person who was so closely related to a Neanderthal" comments Svante Paabo from the Max Planck Institute for Evolutionary Anthropology who led the study. "I could hardly believe it when we first saw the results." "We hope that DNA from other human fossils that predate the extinction of Neanderthals will help reconstruct the interactions between Neanderthals and modern humans in even more detail," says Mateja Hajdinjak, another key researcher involved in the study.

「能夠從一位與尼安德塔人關係親近的人身上取得DNA，完全是一件幸運至極且出乎意料的事。」領導本研究，來自馬克斯·普朗克演化人類學研究所的Svante Paabo評論。「第一眼看到結果時我們相當難以置信。」「我們希望其他年代為尼安德塔人絕種之前的人類化石中的DNA，可以幫助我們重建尼安德塔人與現代人間是如何互動的更多細節。」 參與本研究的另一位主要科學家，Mateja Hajdinjak說。

"When we started the work on Oase site, everything was already pointing to an exceptional discovery," remembers Oana Moldovan, the Romanian researcher who initiated the systematic excavation of the cave in 2003. "But such discoveries require painstaking research to be confirmed," adds Silviu Constantin, her colleague who worked on dating of the site. "We have previously shown that Oase is indeed the oldest modern human in Europe known so far, and now this research confirms that the individual had a Neanderthal ancestor. What more could we wish for?"

「當我們開始著手Oase遺址的考古工作時，所有跡象就已經指出這裡會有重大發現。」羅馬尼亞學者Oana Moldovan回憶道，她於2003年開始對此洞穴進行系統性的開挖。「但要證實這種大發現需要眾人辛勤的研究，」她的同事Silviu Constantin補充說，其研究為對此遺址進行定年。「我們之前已經顯示Oase確實是目前為止歐洲最古老的現代人，而現在本研究又確認了他有位尼安德塔人祖先。我們還能夠奢求什麼呢？」

引用自：Max-Planck-Gesellschaft. "Early modern humans interbred with Neanderthals: An early European had a close Neanderthal ancestor." ScienceDaily. ScienceDaily, 22 June 2015. 

原文網址：http://www.sciencedaily.com/releases/2015/06/150622122718.htm