人類的進化史，可不止一條

Fossil by fossil, scientists over the last 40 years have suspected that their models for the more immediate human family tree — the single trunk, straight as a Ponderosa pine, up from Homo habilis to Homo erectus to Homo sapiens — were oversimplified. The day for that serious revision may be at hand.

在過去40年中，通過研究每一個化石，科學(xué)家們懷疑現(xiàn)代人類的進化樹模型——一條如黃松般筆直的樹干, 從下往上依次是能人(Homo habilis)、直立人(Homo erectus)和智人(Homo sapiens) ——過于簡單。大幅修訂進化圖的時刻可能已經(jīng)到來了。

The discovery of three new fossil specimens, announced Wednesday, is the most compelling evidence yet for multiple lines of evolution in our own genus, Homo, scientists said. The fossils showed that there were at least two contemporary Homo species, in addition to Homo erectus, living in East Africa as early as two million years ago.

研究員表示，周三宣布的三個新化石樣本，為證明我們?nèi)祟悡碛卸鄺l進化路線提供了最有力證據(jù)。這些化石表明，早在兩百萬年前，除了直立人外，同時期至少還有其他兩個人種生活在東非。

 

梅亞維·利基(Meave Leakey)和弗雷德·斯普爾(Fred Spoor)在新頭骨化石KNM-ER 62000的發(fā)現(xiàn)地附近收集化石。

Uncovered from sandstone at Koobi Fora, badlands near Lake Turkana in Kenya, the specimens included a well-preserved skull of a late juvenile with a relatively large braincase and a long, flat face, which has been designated KNM-ER 62000 (62000 for short). It bears a striking resemblance to the enigmatic cranium known as 1470, the center of debate over multiple lineages since its discovery in the same area in 1972.

這些化石來自肯尼亞圖爾卡納湖附近的庫比福勒荒原地帶的沙巖中，其中包括一個保存完好的青少年頭骨，他的腦部較大、面部長且平，編號為KNM-ER 62000(簡稱62000)。它與神秘的1470號頭骨化石有著驚人的相似之處。1972年，人們在同一地區(qū)發(fā)現(xiàn)了1470號化石，從那以后，它就成為了進化途徑方面爭論的焦點。

If the 62000 skull showed that 1470 was not a single odd individual, the other two specimens seemed to provide a vital piece of evidence that had been missing. The specimen 1470 had no mandible, or lower jaw. The new finds included an almost complete lower jaw (60000) — considered to be the most complete mandible of an early Homo yet found — and a part of another lower jaw (62000).

如果62000號頭骨化石的出現(xiàn)說明了1470號人不是一個單個的特殊個體, 那另外兩個樣本似乎提供了此前缺失的關(guān)鍵證據(jù)。1470號化石沒有下頜骨，或者下頜。在新發(fā)現(xiàn)的化石中，有一個幾乎完整的下頜化石(60000)，這是到目前為止發(fā)現(xiàn)的最完整的早期人類下頜，另外一塊是有著部分下頜的化石(62000)。

The fossils were collected between 2007 and 2009 by a team led by Meave and Louise Leakey, the mother-and-daughter paleoanthropologists of the Koobi Fora Research Project and members of the famous African fossil-hunting family. Dr. Meave Leakey is the wife of Richard Leakey, a son of Louis and Mary Leakey, who produced the early evidence supporting Africa’s central place in early human origins. Mr. Leakey divides his time between Stony Brook University on Long Island, where he is a professor of anthropology, and the Turkana Basin Institute in Kenya.

2007年到2009年間，庫比福勒研究項目的古人類學(xué)者梅亞維·利基(Meave Leakey)和路易斯·利基(Louise Leakey)領(lǐng)導(dǎo)的團隊發(fā)現(xiàn)了這些化石。這對母女出身于非洲著名的化石搜尋家族。梅亞維·利基博士的丈夫是理查德·利基(Richard Leakey)，理查德的父母路易斯·利基(Louis Leakey)和瑪麗·利基(Mary Leakey)為證明非洲在早期人類起源中的主要地位提供了初期證據(jù)。理查德是長島石溪大學(xué)(Stony Brook University)的一名人類學(xué)教授，他一直在石溪大學(xué)和肯尼亞的圖爾卡納湖盆地研究所(Turkana Basin Institute)之間奔波。

After looking “long and hard” for fossils to confirm the intriguing features of 1470’s face and show what its teeth and lower jaw were like, Dr. Meave Leakey said this week, “At last we have some answers.”

梅亞維博士經(jīng)過“長時間的艱難尋找”，終于找到化石確認了1470號人種的有趣臉部特征，并向人們展示它的牙齒和下顎構(gòu)造。梅亞維·利基博士上周表示，“我們最終得到了一些答案。”

The real crux of matter, said Susan C. Antón of New York University, a member of the team, is how the discovery shapes the interpretation of 1470’s place in the early world of Homo. “These fossils are anatomically like 1470, and we now have some teeth,” she said. “We are more certain that 1470 was not a one-off, and not everything 1470 is big.”

紐約大學(xué)(New York University)的蘇珊·C·安東(Susan C. Antón)是團隊一員，她表示，這項發(fā)現(xiàn)是如何改變了對1470號化石在古人類研究中的地位的看法，才是事情的關(guān)鍵。“這些化石的解剖特征與1470號化石相似，而且我們現(xiàn)在有了一些牙齒，”她說。“我們更加確定，1470不是獨一無二的，而且1470也不是所有部位都很大。”

In their first formal report, Dr. Leakey and her colleagues wrote in the journal Nature, “These three specimens will greatly aid the reassessment of the systematics and early radiation of the genus Homo.”

梅維亞·利基博士和同事在《自然》(Nature)上發(fā)表了他們的第一份正式報告，其中寫道，“這三個化石樣本為重新評估人類體系和早期人類分布提供了極大幫助。”

They, however, chose not to assign the fossils to any existing or new species until more analysis is conducted on contemporary hominids. The 1470 specimen was two million years old; the new face and fragmentary jaw are 1.9 million to 1.95 million years old; the better-preserved lower jaw is younger still, at 1.83 million years old.

盡管如此，他們認為在對當代人類進行更多研究之前，不應(yīng)該把這些化石歸類為任何現(xiàn)存的或新的物種。1470號化石樣本有著200萬年的歷史;新發(fā)現(xiàn)的臉部和破碎的頜骨的歷史在190萬年到195萬年之間;那個保存更為完好的下頜骨的歷史較短，在183萬年左右。

Fred Spoor, a member of the discovery team who directed the laboratory analysis, said in a news teleconference that the research showed clearly that “human evolution is not this straight line it was once thought to be.” Instead, East Africa, he said, “was quite a crowded place, with multiple species” with presumably different diets.

探險隊的成員、負責(zé)實驗分析的弗雷德·斯普爾(Fred Spoor)在一次遠程新聞發(fā)布會中說，研究明確顯示，“人類進化并不像以前認為的那樣，是一條直線。”他說，東非“過去是個十分擁擠的地方，有很多人種”，而且這些人種還可能依賴不同食物。

Dr. Spoor is a paleoanthropologist at University College London and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. The lab work was supported by the institute. The fieldwork was financed by the National Geographic Society, and the dating of the fossils, mainly by Craig S. Feibel of Rutgers University, was supported by the Leakey Foundation.

斯普爾是倫敦大學(xué)學(xué)院(University College London)和德國萊比錫的馬克斯·普朗克進化人類學(xué)研究所(Max Planck Institute for Evolutionary Anthropology) 的古人類學(xué)家。實驗工作得到了該研究所的支持。國家地理學(xué)會(National Geographic Society)為野外勘探工作提供了資金，化石的年代測定工作主要由來自羅格斯大學(xué)(Rutgers University)的克雷格·S·費貝爾(Craig S. Feibel)完成，由利基基金會(Leakey Foundation)提供贊助。

Although a few specialists in human origins questioned whether the still sparse evidence was sufficient to back the new conclusions, Ian Tattersall of the American Museum of Natural History in New York City, who was not involved in the new discovery, concluded, “This new material certainly substantiates the idea, long gathering ground, that multiple lineages of early Homo are present in the record at Koobi Fora.”

雖然一些人類起源專家仍然質(zhì)疑，目前尚不充分的證據(jù)是否足以支持那些新的結(jié)論。紐約市美國自然歷史博物館(American Museum of Natural History)的伊恩·塔特薩爾(Ian Tattersall) 并沒有參與這項新發(fā)現(xiàn)，但他則認為，“這個新材料必然證實了那個逐漸獲得認可的觀點，庫比福勒的化石顯示，早期人類的發(fā)展存在多個體系。”

Dr. Tattersall continued, “And it supports the view that the early history of Homo involved vigorous experimentation with the biological and behavioral potential of the new genus, instead of a slow process of refinement in a central lineage.”

塔特薩爾接著說，“這也支持了一個觀點，人類的早期歷史涉及對新種屬的生物和行為潛能進行有力試驗，而不是以一個種屬為發(fā)展中軸線的緩慢改進過程。”

Bernard Wood of George Washington University, who has studied the early Homo fossil record, wrote in a companion article in Nature, “In a nutshell, the anatomy of the specimens supports the hypothesis of multiple early Homo species.”

喬治·華盛頓大學(xué)(George Washington University)的伯納德·伍德(Bernard Wood)研究過早期人類化石記錄，他在《自然》(Nature)的一篇相關(guān)文章中寫道，“總而言之，對這些樣本的解剖分析支持了早期人種具有多樣性的假說。”

Dr. Wood then weighed the pros and cons of placing the new fossils with the species H. habilis, first discovered in 1964, or a separate and controversial parallel species known as H. rudolfensis, to which 1470 has often been tentatively assigned. H. erectus emerged around the same time, joining the other two species in Africa.

之后，伍德權(quán)衡了把新發(fā)現(xiàn)的化石和發(fā)現(xiàn)于1964年的能人化石樣本，或者和一個獨立而具有爭議性的平行人種——魯?shù)婪蛉?1470號人經(jīng)常被暫時歸入此類)——歸于一類的利與弊。直人大概出現(xiàn)在同一時期，加入了非洲另外兩個人種的行列。

Chris Stringer of the Natural History Museum of London, who had no part in the research, agreed that it looked as if the new discoveries “confirm the distinctiveness of 1470” and “therefore confirm the existence of a distinctive kind of early human around 1.8 to 2.0 million years ago.” But he noted that “there remain many uncertainties” about the 1470 fossil “and whether it might still be just a large specimen of Homo habilis.”

倫敦自然歷史博物館(Natural History Museum of London)的克里斯·斯特林格(Chris Stringer)未參與研究。他同意新的發(fā)現(xiàn)似乎“肯定了1470號人的獨特性”，并且“確定了在大約180萬到200萬年前，的確存在一種不同種類的早期人類。”但是，他指出，關(guān)于1470號化石以及“它是否仍然只是能人的一個大型樣本，仍存在很多疑問”。