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新化石显示人类拥有多条进化路线

New Fossils Indicate Early Branching of Human Family Tree
新化石显示人类拥有多条进化路线

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.

在过去40年中,通过研究每一个化石,科学家们怀疑现代人类的进化树模型——一条如黄松般笔直的树干, 从下往上依次是能人(Homo habilis)、直立人(Homo erectus)和智人(Homo sapiens) ——过于简单。大幅修订进化图的时刻可能已经到来了。

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.

研究员表示,周三宣布的三个新化石样本,为证明我们人类拥有多条进化路线提供了最有力证据。这些化石表明,早在两百万年前,除了直立人外,同时期至少还有其他两个人种生活在东非。
 

梅亚维·利基(Meave Leakey)和弗雷德·斯普尔(Fred Spoor)在新头骨化石KNM-ER 62000的发现地附近收集化石。

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.

这些化石来自肯尼亚图尔卡纳湖附近的库比福勒荒原地带的沙岩中,其中包括一个保存完好的青少年头骨,他的脑部较大、面部长且平,编号为KNM-ER 62000(简称62000)。它与神秘的1470号头骨化石有着惊人的相似之处。1972年,人们在同一地区发现了1470号化石,从那以后,它就成为了进化途径方面争论的焦点。

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号头骨化石的出现说明了1470号人不是一个单个的特殊个体,  那另外两个样本似乎提供了此前缺失的关键证据。1470号化石没有下颌骨,或者下颌。在新发现的化石中,有一个几乎完整的下颌化石(60000),这是到目前为止发现的最完整的早期人类下颌,另外一块是有着部分下颌的化石(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年间,库比福勒研究项目的古人类学者梅亚维·利基(Meave Leakey)和路易斯·利基(Louise Leakey)领导的团队发现了这些化石。这对母女出身于非洲著名的化石搜寻家族。梅亚维·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)和玛丽·利基(Mary Leakey)为证明非洲在早期人类起源中的主要地位提供了初期证据。理查德是长岛石溪大学(Stony Brook University)的一名人类学教授,他一直在石溪大学和肯尼亚的图尔卡纳湖盆地研究所(Turkana Basin Institute)之间奔波。

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.”

梅亚维博士经过“长时间的艰难寻找”,终于找到化石确认了1470号人种的有趣脸部特征,并向人们展示它的牙齿和下颚构造。梅亚维·利基博士上周表示,“我们最终得到了一些答案。”

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.”

纽约大学(New York University)的苏珊·C·安东(Susan C. Antón)是团队一员,她表示,这项发现是如何改变了对1470号化石在古人类研究中的地位的看法,才是事情的关键。“这些化石的解剖特征与1470号化石相似,而且我们现在有了一些牙齿,”她说。“我们更加确定,1470不是独一无二的,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.”

梅维亚·利基博士和同事在《自然》(Nature)上发表了他们的第一份正式报告,其中写道,“这三个化石样本为重新评估人类体系和早期人类分布提供了极大帮助。”

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.

尽管如此,他们认为在对当代人类进行更多研究之前,不应该把这些化石归类为任何现存的或新的物种。1470号化石样本有着200万年的历史;新发现的脸部和破碎的颌骨的历史在190万年到195万年之间;那个保存更为完好的下颌骨的历史较短,在183万年左右。

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.

探险队的成员、负责实验分析的弗雷德·斯普尔(Fred Spoor)在一次远程新闻发布会中说,研究明确显示,“人类进化并不像以前认为的那样,是一条直线。”他说,东非“过去是个十分拥挤的地方,有很多人种”,而且这些人种还可能依赖不同食物。

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.

斯普尔是伦敦大学学院(University College London)和德国莱比锡的马克斯·普朗克进化人类学研究所(Max Planck Institute for Evolutionary Anthropology) 的古人类学家。实验工作得到了该研究所的支持。国家地理学会(National Geographic Society)为野外勘探工作提供了资金,化石的年代测定工作主要由来自罗格斯大学(Rutgers University)的克雷格·S·费贝尔(Craig S. Feibel)完成,由利基基金会(Leakey Foundation)提供赞助。

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.”

虽然一些人类起源专家仍然质疑,目前尚不充分的证据是否足以支持那些新的结论。纽约市美国自然历史博物馆(American Museum of Natural History)的伊恩·塔特萨尔(Ian Tattersall) 并没有参与这项新发现,但他则认为,“这个新材料必然证实了那个逐渐获得认可的观点,库比福勒的化石显示,早期人类的发展存在多个体系。”

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.”

塔特萨尔接着说,“这也支持了一个观点,人类的早期历史涉及对新种属的生物和行为潜能进行有力试验,而不是以一个种属为发展中轴线的缓慢改进过程。”

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.”

乔治·华盛顿大学(George Washington University)的伯纳德·伍德(Bernard Wood)研究过早期人类化石记录,他在《自然》(Nature)的一篇相关文章中写道,“总而言之,对这些样本的解剖分析支持了早期人种具有多样性的假说。”

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,伍德权衡了把新发现的化石和发现于1964年的能人化石样本,或者和一个独立而具有争议性的平行人种——鲁道夫人(1470号人经常被暂时归入此类)——归于一类的利与弊。直人大概出现在同一时期,加入了非洲另外两个人种的行列。

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.”

伦敦自然历史博物馆(Natural History Museum of London)的克里斯·斯特林格(Chris Stringer)未参与研究。他同意新的发现似乎“肯定了1470号人的独特性”,并且“确定了在大约180万到200万年前,的确存在一种不同种类的早期人类。”但是,他指出,关于1470号化石以及“它是否仍然只是能人的一个大型样本,仍存在很多疑问”。
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