以色列頭蓋骨講述人類走出非洲的故事

Anthropologists exploring a cave in Israel have uncovered a rare 55,000-year-old skull fossil that they say has a story to tell of a reverberating transition in human evolution, at a point when and where some early humans were moving out of Africa and apparently interbreeding with Neanderthals.

古人類學家在以色列探索一座洞穴時發現了一枚5.5萬年前的頭骨化石，他們認爲，這隻頭骨揭示了人類進化史上一次意義深遠的轉變。那是在早期人類離開非洲的時候，並且在大遷徙中可能與尼安德特人發生了混血。

The story is of when the Levant was a corridor for anatomically modern humans who were expanding out of Africa and then across Eurasia, replacing all other forms of early human-related species. Given the scarcity of human fossils from that time, scholars say, these ancestors of present-day non-African populations had remained largely enigmatic.

當時，黎凡特地帶是一條遷徙走廊，解剖學意義上的現代人從這裏走出非洲，走向亞歐大陸，取代了其他所有的早期類人物種。學者說，那個年代遺留下來的人類化石很少，因此，今天非洲以外人類的祖先的情況仍然是個謎。

From the new fossil find, which could be closely related to the first modern humans to colonize Stone Age Europe, it appears that these people already had physical traits a bit different from the Africans they were leaving behind and many other human inhabitants along the corridor.

最近發現的這具化石可能與石器時代移民歐洲的第一批人類關係很近，從化石來看，這羣人已經具備了一些特徵，與當時留在非洲大陸的人類、以及黎凡特走廊沿線其他人類頗不相同。

Could this support recent genetic evidence that modern Homo sapiens and their Neanderthal cousins interbred, perhaps in the Middle East and most likely between 65,000 and 47,000 years ago? The discovery team urged caution on the interbreeding issue, but noted anatomical features of the cranium suggesting that some human-Neanderthal mixture had presumably occurred before any encounters in Europe and Asia.

近來有基因證據表明，現代智人可能在中東地區與他們的近親尼安德特人交配，時間大約是6.5萬到4.7萬年間。這具化石是否支持了這種基因證據？發掘小組的科學家強調在交配假說的問題上需要慎重，但指出，頭蓋骨的解剖學特徵表明，一些智人與尼安德特人混合的跡象可能在這兩種人在歐洲和亞洲相遇前，就已經出現了。

The discovery in Manot Cave in western Galilee, made in 2008 and subjected to years of rigorous analysis, was reported on Wednesday in the journal Nature by an international team of researchers led by Israel Hershkovitz of Tel Aviv University. They said this was “the first fossil evidence from the critical period when genetic and archaeological models predict that African modern humans successfully migrated out of Africa and colonized Eurasia.”

在加利利西部馬諾特洞穴(Manot Cave)發現的化石是2008年出土的，經過了多年嚴謹的分析。研究結果由一個多國科學家組成的科研小組於週三發表在《自然》雜誌上，他們的領隊是特拉維夫大學的伊斯拉埃爾·赫什科維茨(Israel Hershkovitz)。他們說，這是“來自一個關鍵歷史時期的第一份化石證據，基因和考古模型已經預言，非洲現代人類就是在那個時期成功走出非洲，在歐亞大陸定居的”。

The researchers further concluded that the Manot specimen “provides important clues about the morphology of modern humans in close chronological proximity to a probable interbreeding event with Neanderthals.” They also noted that the shape of the cranium established this as a fully modern human at a time when warmer and wetter conditions were favorable for human migration out of Africa.

研究者還進一步得出結論，認爲馬諾特標本“爲現代人類在與尼安德特人發生可能的交配活動前後的形態學特徵提供了重要線索”。他們又說，這枚頭蓋骨經證明屬於一個完全意義上的現代人；當時相對更溫暖溼潤的氣候有利於人類走出非洲。

In other words, Dr. Hershkovitz said in an interview, the Manot cranium “is the missing connection between African and European populations.”

換言之，馬諾特頭蓋骨“是非洲人類和歐洲人類之間缺失的中間環節”，赫什科維茨接受採訪時說。

Scientists not involved with the research team praised the “fascinating new fossil” and the cautious interpretation of its broader implications in understanding the early migrations into Eurasia. “This fossil fits previous predictions,” said Eric Delson, a paleoanthropologist at Lehman College of the City University of New York, “which is a nice rarity in our field.”

未參與這個研究項目的科學家讚揚了這塊“奇妙的新化石”的發現，以及關於它對理解人類進入亞歐大陸過程的意義的謹慎解讀。“這塊化石與此前的預言吻合，這在我們這個學科領域，是少有的，”紐約市立大學李曼學院的古人類學家埃裏克·戴爾森(Eric Delson)說。

Dr. Delson, also a researcher at the American Museum of Natural History, added, “As always, we want more fossils to document variations in and details about this presumed fossil population.”

戴爾森還是美國自然歷史博物館的研究員，他補充說：“我們總是希望獲得更多化石樣本，以便記錄這個可能存在的羣體的變異和有關他們的詳細情況。”

In an email, Dr. Delson praised the journal authors “for hitting the mark with their analyses and interpretations, reaching all the possible conclusions one could think of: The partial skull combines a basically modern human form with a few features also found in Neanderthals.” In addition, he pointed out, the analysis “supports the similarity of its shapes” to those of modern Africans and early modern humans from Europe, such as the Cro-Magnons.

戴爾森在電子郵件中讚揚論文作者的“分析和解讀十分恰當，得出了我們能想像得到的所有結論：這塊頭骨既有現代人類的基本特徵，也有一些尼安德特人的特徵”。此外，他也指出，他們的分析“可以支持頭骨形狀近似”現代非洲人和早期歐洲人——比如克羅馬儂人——的事實。

The partial skull, designated Manot 1, is of a fairly small adult individual, its sex undetermined. The distinctive bunlike shape at the base of the skull resembles modern African and European skulls but differs from other anatomically modern humans from the Levant, and is thus a strong clue that these were among the first humans to settle Europe, scientists said.

這塊頭蓋骨被命名爲馬諾特1號，屬於一個身材較小的成年人，性別待定。顱骨基部明顯的髻狀突起接近現代非洲人和歐洲人，但有別於其他在黎凡特地帶發現的現代人種，因此強有力地暗示着，這可能是早期進入歐洲的人類。

Dr. Delson agreed that the evidence “makes it possible that this individual is (or is descended from) a ‘hybrid’ between modern humans and Neanderthals, but as the authors note, such a conclusion cannot be reached from a single fossil, especially as hybrids between species of modern primates usually have some genetically related anatomical oddities.”

戴爾森同意，這些證據“可能說明這個人是現代人與尼安德特人的混血（或其後代）。但正如論文作者所說的，不能從一塊化石就得出這樣的結論，特別是考慮到現代靈長類動物的跨物種混血後代往往都存在某些遺傳上的解剖學異常”。

One concern is that the fossil skull is fairly small, with a somewhat lower braincase capacity than in modern humans. With only one specimen, it is hard to know whether this is normal for the general population, scientists said. And Dr. Delson said it would be interesting to test for DNA in the skull to support its possible hybrid status in a time of overlapping modern human-Neanderthal populations when early humans were making their way, as he phrased it, to “that small zoological backwater of Eurasia known as Europe.”

顧慮之一，是這件顱骨化石相對較小，腦容量比現代人小。因爲只有一件化石標本，科學家很難判斷，這是不是這個羣體的普遍特徵。戴爾森說，如果能檢測頭骨的DNA，從而證實這的確是現代人與尼安德特人共存時代的一個混血人種，那將是很誘人的。他說，“今天所謂的歐洲，是亞歐大陸物種進化的一個小支流”。

Excavations at Manot Cave are expected to continue through at least 2020, searching deeper for more fossils and artifacts from the migrating people. Israel, Dr. Hershkovitz said, “is like a Swiss cheese, lots of caves everywhere.”

在馬諾特洞穴的挖掘預計將至少持續到2020年，更加深入地尋找更多遷徙人類留下來的化石和器物。赫什科維茨說，以色列就像“一塊瑞士奶酪，到處都是窟窿”。

Several caves in the vicinity of Manot were occupied for long times by Neanderthals between 65,000 and 50,000 years ago. In this respect, Dr. Hershkovitz said, Manot is an excellent place to search for possible hybrids, but they may be difficult to recognize from surface features. “Only DNA study will solve the problem,” he said.

馬諾特洞穴附近的一些洞穴，在6.5到5萬年前，長期被尼安德特人棲居。考慮到這一點，赫什科維茨說，馬諾特是尋找混血人種的理想場所，但從表面特徵上，可能很難識別。“只有DNA研究能給我們答案，”他說。