人類的進(jìn)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(guò)去40年中，通過(guò)研究每一個(gè)化石，科學(xué)家們懷疑現(xiàn)代人類的進(jìn)化樹(shù)模型——一條如黃松般筆直的樹(shù)干, 從下往上依次是能人(Homo habilis)、直立人(Homo erectus)和智人(Homo sapiens) ——過(guò)于簡(jiǎn)單。大幅修訂進(jìn)化圖的時(shí)刻可能已經(jīng)到來(lái)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(gè)新化石樣本，為證明我們?nèi)祟悡碛卸鄺l進(jìn)化路線提供了最有力證據(jù)。這些化石表明，早在兩百萬(wàn)年前，除了直立人外，同時(shí)期至少還有其他兩個(gè)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(lái)自肯尼亞圖爾卡納湖附近的庫(kù)比福勒荒原地帶的沙巖中，其中包括一個(gè)保存完好的青少年頭骨，他的腦部較大、面部長(zhǎng)且平，編號(hào)為KNM-ER 62000(簡(jiǎn)稱62000)。它與神秘的1470號(hào)頭骨化石有著驚人的相似之處。1972年，人們?cè)谕坏貐^(qū)發(fā)現(xiàn)了1470號(hào)化石，從那以后，它就成為了進(jìn)化途徑方面爭(zhēng)論的焦點(diǎn)。

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(hào)頭骨化石的出現(xiàn)說(shuō)明了1470號(hào)人不是一個(gè)單個(gè)的特殊個(gè)體, 那另外兩個(gè)樣本似乎提供了此前缺失的關(guān)鍵證據(jù)。1470號(hào)化石沒(méi)有下頜骨，或者下頜。在新發(fā)現(xiàn)的化石中，有一個(gè)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(kù)比福勒研究項(xiàng)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(tuán)隊(duì)發(fā)現(xiàn)了這些化石。這對(duì)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(zhǎng)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(guò)“長(zhǎng)時(shí)間的艱難尋找”，終于找到化石確認(rèn)了1470號(hào)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(tuán)隊(duì)一員，她表示，這項(xiàng)發(fā)現(xiàn)是如何改變了對(duì)1470號(hào)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(hào)化石相似，而且我們現(xiàn)在有了一些牙齒，”她說(shuō)。“我們更加確定，1470不是獨(dú)一無(wú)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(bào)告，其中寫(xiě)道，“這三個(gè)化石樣本為重新評(píng)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(rèn)為在對(duì)當(dāng)代人類進(jìn)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(hào)化石樣本有著200萬(wàn)年的歷史;新發(fā)現(xiàn)的臉部和破碎的頜骨的歷史在190萬(wàn)年到195萬(wàn)年之間;那個(gè)保存更為完好的下頜骨的歷史較短，在183萬(wàn)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(xiǎn)隊(duì)的成員、負(fù)責(zé)實(shí)驗(yàn)分析的弗雷德·斯普爾(Fred Spoor)在一次遠(yuǎn)程新聞發(fā)布會(huì)中說(shuō)，研究明確顯示，“人類進(jìn)化并不像以前認(rèn)為的那樣，是一條直線。”他說(shuō)，東非“過(guò)去是個(gè)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(guó)萊比錫的馬克斯·普朗克進(jìn)化人類學(xué)研究所(Max Planck Institute for Evolutionary Anthropology) 的古人類學(xué)家。實(shí)驗(yàn)工作得到了該研究所的支持。國(guó)家地理學(xué)會(huì)(National Geographic Society)為野外勘探工作提供了資金，化石的年代測(cè)定工作主要由來(lái)自羅格斯大學(xué)(Rutgers University)的克雷格·S·費(fèi)貝爾(Craig S. Feibel)完成，由利基基金會(huì)(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(guó)自然歷史博物館(American Museum of Natural History)的伊恩·塔特薩爾(Ian Tattersall) 并沒(méi)有參與這項(xiàng)新發(fā)現(xiàn)，但他則認(rèn)為，“這個(gè)新材料必然證實(shí)了那個(gè)逐漸獲得認(rèn)可的觀點(diǎn)，庫(kù)比福勒的化石顯示，早期人類的發(fā)展存在多個(gè)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(shuō)，“這也支持了一個(gè)觀點(diǎn)，人類的早期歷史涉及對(duì)新種屬的生物和行為潛能進(jìn)行有力試驗(yàn)，而不是以一個(gè)種屬為發(fā)展中軸線的緩慢改進(jìn)過(guò)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(guò)早期人類化石記錄，他在《自然》(Nature)的一篇相關(guān)文章中寫(xiě)道，“總而言之，對(duì)這些樣本的解剖分析支持了早期人種具有多樣性的假說(shuō)。”

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(gè)獨(dú)立而具有爭(zhēng)議性的平行人種——魯?shù)婪蛉?1470號(hào)人經(jīng)常被暫時(shí)歸入此類)——歸于一類的利與弊。直人大概出現(xiàn)在同一時(shí)期，加入了非洲另外兩個(gè)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(hào)人的獨(dú)特性”，并且“確定了在大約180萬(wàn)到200萬(wàn)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(hào)化石以及“它是否仍然只是能人的一個(gè)大型樣本，仍存在很多疑問(wèn)”。