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南非洞穴内发现新人种骨骼化石

更新时间:2015-9-13 9:39:22 来源:纽约时报中文网 作者:佚名

New Species of Human Ancestor Is Found in a South African Cave
南非洞穴内发现新人种骨骼化石

Acting on a tip from spelunkers two years ago, scientists in South Africa discovered what the cavers had only dimly glimpsed through a crack in a limestone wall deep in the Rising Star cave: lots and lots of old bones.

两年前,南非科学家按照洞穴探险爱好者的指引,在启星洞(Rising Star Cave)深处发现了探洞者通过石灰岩壁上的缝隙隐约瞥见的东西:大量古老的骨头。

The remains covered the earthen floor beyond the narrow opening. This was, the scientists concluded, a large, dark chamber for the dead of a previously unidentified species of the early human lineage — Homo naledi.

狭窄洞口内的泥土表面上铺满了骨骸。科学家得出结论,在这个巨大、漆黑的洞穴里面放着的遗体,来自一种属于早期人类谱系的不知名物种——“纳勒迪人”(Homo naledi)。

The new hominin species was announced on Thursday by an international team of more than 60 scientists led by Lee R. Berger, an American paleoanthropologist who is a professor of human evolution studies at the University of the Witwatersrand in Johannesburg. The species name, H. naledi, refers to the cave where the bones lay undisturbed for so long; “naledi” means “star” in the local Sesotho language.

美国古人类学家李·R·伯杰教授(Lee R. Berger) 带领的一个国际团队在周四公布了这种新的人亚族(hominin)物种,团队由60多名科学家组成。伯杰在约翰内斯堡的金山大学(University of the Witwatersrand)任人类演化学教授。物种的命名取自那个让骨骸得以安然保存至今的洞穴;在塞索托语(Sesotho)里, “纳勒迪”的意思是  “星星”。

In two papers published this week in the open-access journal eLife, the researchers said that the more than 1,550 fossil elements documenting the discovery constituted the largest sample for any hominin species in a single African site, and one of the largest anywhere in the world. Further, the scientists said, that sample is probably a small fraction of the fossils yet to be recovered from the chamber. So far the team has recovered parts of at least 15 individuals.

在两篇本周刊登于开放阅读期刊《eLife》的文章里,研究人员说,该发现记录了超过1500件化石,是非洲单个考古地点中发现人亚族样本最多的一处,在全世界范围内也居于前列。接着,科学家们还说,洞穴中可能还有大量化石有待发掘,目前发现的这些只是一小部分。目前团队已经找到了最少15个个体的身体部分。

“With almost every bone in the body represented multiple times, Homo naledi is already practically the best-known fossil member of our lineage,” Dr. Berger said.

“‘纳勒迪人’身体上的几乎所有骨头都出现过很多次,事实上他们已经是我们这一谱系中得到了最多了解的化石成员,”伯杰说。

Besides introducing a new member of the prehuman family, the discovery suggests that some early hominins intentionally deposited bodies of their dead in a remote and largely inaccessible cave chamber, a behavior previously considered limited to modern humans. Some of the scientists referred to the practice as a ritualized treatment of their dead, but by “ritual” they said they meant a deliberate and repeated practice, not necessarily a kind of religious rite.

除了引出一个前人类家族的新成员,该发现还表明,一些早期人亚族动物会故意把死者遗体存放在一个偏僻且很难进入的洞穴里,这是一种以前被认为只限于现代人的行为。一些科学家把这种做法归为对遗体的一种仪式性活动,但科学家们说,在“仪式”这个词上,他们是指故意和反复的活动,而不一定是一种宗教仪式。

“It’s very, very fascinating,” said Ian Tattersall, an authority on human evolution at the American Museum of Natural History in New York, who was not involved in the research. “No question there’s at least one new species here,” he added, “but there may be debate over the Homo designation, though the species is quite different from anything else we have seen.”

“这非常、非常令人着迷,” 纽约的美国自然历史博物馆 (American Museum of Natural History)的人类演化研究权威伊安·泰特萨(Ian Tattersall)说。他没有参与该研究。“毫无疑问这里至少有一个新的物种,”他还说, “但是否归入人属(Homo)可能存有争论,尽管该物种和我们之前见过的任何物种都相当不一样。”

A colleague of Dr. Tattersall’s at the museum, Eric Delson, who also is a professor at Lehman College of the City University of New York, was also impressed, saying, “Berger does it again!”

泰特萨在博物馆的同事、纽约市立大学李曼学院(Lehman College of the City University of New York)教授埃里克·戴尔森(Eric Delson)也对这项研究十分激赏,说这是“伯杰再次出手!”

Dr. Delson was referring to Dr. Berger’s previous headline discovery, published in 2010, also involving cave deposits at the Cradle of Humankind site, 30 miles northwest of Johannesburg. He found many fewer fossils that time, but enough to conclude he was looking at a new species, which he named Australopithecus sediba. Geologists said the individuals lived 1.78 million to 1.95 million years ago, when australopithecines and early species of Homo were contemporaries.

戴尔森指的是伯杰在2010年发表的另一项轰动发现,其中也涉及到位于约翰内斯堡西北30英里(约合48公里)处的“人类摇篮”内的洞穴。那次他找到的化石比这次少得多,但也足以得出找到了新物种的结论,他把该新物种命名为南方古猿源泉种(Australopithecus sediba)。地质学家说,该物种在178万至195万年前生活在地球上,古猿和人属早期物种存在于同一时期。

Researchers analyzing the H. naledi fossils have not yet nailed down their age, which is difficult to measure because of the muddled chamber sediments and the absence of other fauna remains nearby. Some of its primitive anatomy, like a brain no larger than an average orange, Dr. Berger said, indicated that the species evolved near or at the root of the Homo genus, meaning it must be in excess of 2.5 million to 2.8 million years old. Geologists think the cave is no older than three million years.

负责分析纳勒迪人化石的研究人员还没测定出化石的年代,由于洞穴内的沉积物混杂在一起,化石周围亦没有其他动物遗骸,因此年代测定会很困难。伯杰说,从一些原始的解剖构造看,比如顶多只有普通橙子大小的大脑,此物种已演化到接近或到达人属之初,也就是说肯定超过了250到280万年。地质学家认为洞穴的存在时间不会超过300万年。

The field work and two years of analysis for Dr. Berger’s latest discovery were supported by the University of the Witwatersrand, the National Geographic Society and the South African Department of Science and Technology/National Research Foundation. In addition to the journal articles, the findings will be featured in the October issue of National Geographic Magazine and in a two-hour NOVA/National Geographic documentary to air Wednesday on PBS.

伯杰此次新发现的实地工作及两年的分析工作均由金山大学、国家地理学会(National Geographic Society)和南非科学与技术部(South African Department of Science and Technology)/南非国家研究基金会(South Africa National Research Foundation)提供支持。除学术论文外,此次发现还会出现在《国家地理杂志》(National Geographic Magazine)的10月号以及一部2小时的NOVA/国家地理纪录片中,纪录片将于周三在PBS播出。

Scientists on the discovery team and those not involved in the research noted the mosaic of contrasting anatomical features, including more modern-looking jaws and teeth and feet, that warrant the hominin’s placement as a species in the genus Homo, not Australopithecus, the genus that includes the famous Lucy species that lived 3.2 million years ago. The hands of the newly discovered specimens reminded some scientists of the earliest previously identified specimens of Homo habilis, who were apparently among the first toolmakers.

研究团队及没有参与研究的科学家都注意到,新物种包含了一些迥异的解剖特征,包括较像现代人的下颚、牙齿和脚,这就证明应该被归为人属的人亚族物种,而非生活在320万年前的南方古猿属,也就是著名的露西(Lucy)所在的属。新发现物种标本中的手令一些科学家想起了此前已知最早的能人(Homo habilis)标本,而能人看来是最早开始制作工具的物种。

At a news conference on Wednesday, John Hawks of the University of Wisconsin, Madison, a senior author of the paper describing the new species, said it was “unlike any other species seen before,” noting that a small skull with a brain one-third the size of modern human braincases was perched atop a very slender body. An average H. naledi was about five feet tall and weighed almost 100 pounds, he said.

在周三的一场新闻发布会上,论文资深作者、威斯康星大学麦迪逊分校(University of Wisconsin, Madison)的约翰·霍克斯(John Hawks)说,该物种“不像我们之前见过的任何物种”,指出该物种在非常苗条的身体上有一个很小的头骨,以及只有现代人脑壳三分之一大小的大脑。他说,一个普通的纳勒迪人身高大概5尺(约合1.51米),体重将近100磅(约45公斤)。

Tracy Kivell of the University of Kent, in England, an associate of Dr. Berger’s team, was struck by H. naledi’s “extremely curved fingers, more curved than almost any other species of early hominin, which clearly demonstrates climbing capabilities.”

伯杰研究团队成员、英格兰肯特大学(University of Kent)的翠西·凯威尔(Tracy Kivell)说, 让她十分惊讶的是,纳勒迪人“有极度弯曲的手指,比任何早期人亚族物种都要弯,清楚地表明了他们的攀爬能力。”

William Harcourt-Smith of Lehman College of the City University of New York, a researcher at the American Museum of Natural History, led the analysis of the feet of the new species, which he said are “virtually indistinguishable from those of modern humans.” These feet, combined with its long legs, suggest that H. naledi was well suited for upright long-distance walking, Dr. Harcourt-Smith said.

纽约城市大学李曼学院的威廉·哈考特-史密斯(William Harcourt-Smith)亦是美国自然历史博物馆的研究员,他负责对该新物种的脚展开研究,他说他们的脚“与现代人的双脚基本上没分别。”结合他们的长腿,他认为纳勒迪人完全适合长时间直立行走。

In an accompanying commentary in the journal, Chris Stringer, a paleoanthropologist at the Natural History Museum in London, found overall similarities between the new species and fossils from Dmanisi, in the former Soviet republic of Georgia, dated to about 1.8 million years ago. The Georgian specimens are usually assigned to an early variety of Homo erectus.

在期刊随附的一篇评论中,伦敦自然历史博物馆(Natural History Museum in London)的古人类学家克里斯·斯特林格(Chris Stringer)发现,新物种大致上与前苏联格鲁吉亚共和国境内的德马尼西(Dmanisi)发现的化石近似,后者能追溯到约180万年前。格鲁吉亚标本通常被归类为早期直立人(Homo erectus)的一个变种。

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