詳細報道:南非洞穴內發現新人種骨骼化石

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.

兩年前，南非科學家按照洞穴探險愛好者的指引，在啓星洞(Rising Star Cave)深處發現了探洞者通過石灰岩壁上的縫隙隱約瞥見的東西：大量古老的骨頭。

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.

狹窄洞口內的泥土表面上鋪滿了骨骸。科學家得出結論，在這個巨大、漆黑的洞穴裏面放着的遺體，來自一種屬於早期人類譜系的不知名物種——“納勒迪人”(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.

美國古人類學家李·R·伯傑教授(Lee R. Berger) 帶領的一個國際團隊在週四公佈了這種新的人亞族(hominin)物種，團隊由60多名科學家組成。伯傑在約翰內斯堡的金山大學(University of the Witwatersrand)任人類演化學教授。物種的命名取自那個讓骨骸得以安然保存至今的洞穴；在塞索托語(Sesotho)裏， “納勒迪”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.

在兩篇本週刊登於開放閱讀期刊《eLife》的文章裏，研究人員說，該發現記錄了超過1500件化石，是非洲單個考古地點中發現人亞族樣本最多的一處，在全世界範圍內也居於前列。接着，科學家們還說，洞穴中可能還有大量化石有待發掘，目前發現的這些只是一小部分。目前團隊已經找到了最少15個個體的身體部分。

“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.

“‘納勒迪人’身體上的幾乎所有骨頭都出現過很多次，事實上他們已經是我們這一譜系中得到了最多瞭解的化石成員，”伯傑說。

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.

除了引出一個前人類家族的新成員，該發現還表明，一些早期人亞族動物會故意把死者遺體存放在一個偏僻且很難進入的洞穴裏，這是一種以前被認爲只限於現代人的行爲。一些科學家把這種做法歸爲對遺體的一種儀式性活動，但科學家們說，在“儀式”這個詞上，他們是指故意和反覆的活動，而不一定是一種宗教儀式。

“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.”

“這非常、非常令人着迷，” 紐約的美國自然歷史博物館 (American Museum of Natural History)的人類演化研究權威伊安·泰特薩(Ian Tattersall)說。他沒有參與該研究。“毫無疑問這裏至少有一個新的物種，”他還說， “但是否歸入人屬(Homo)可能存有爭論，儘管該物種和我們之前見過的任何物種都相當不一樣。”

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!”

泰特薩在博物館的同事、紐約市立大學李曼學院(Lehman College of the City University of New York)教授埃裏克·戴爾森(Eric Delson)也對這項研究十分激賞，說這是“伯傑再次出手！”

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.

戴爾森指的是伯傑在2010年發表的另一項轟動發現，其中也涉及到位於約翰內斯堡西北30英里（約合48公里）處的“人類搖籃”內的洞穴。那次他找到的化石比這次少得多，但也足以得出找到了新物種的結論，他把該新物種命名爲南方古猿源泉種(Australopithecus sediba)。地質學家說，該物種在178萬至195萬年前生活在地球上，古猿和人屬早期物種存在於同一時期。

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.

負責分析納勒迪人化石的研究人員還沒測定出化石的年代，由於洞穴內的沉積物混雜在一起，化石周圍亦沒有其他動物遺骸，因此年代測定會很困難。伯傑說，從一些原始的解剖構造看，比如頂多只有普通橙子大小的大腦，此物種已演化到接近或到達人屬之初，也就是說肯定超過了250到280萬年。地質學家認爲洞穴的存在時間不會超過300萬年。

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.

伯傑此次新發現的實地工作及兩年的分析工作均由金山大學、國家地理學會(National Geographic Society)和南非科學與技術部(South African Department of Science and Technology)/南非國家研究基金會(South Africa National Research Foundation)提供支持。除學術論文外，此次發現還會出現在《國家地理雜誌》(National Geographic Magazine)的10月號以及一部2小時的NOVA/國家地理紀錄片中，紀錄片將於週三在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.

研究團隊及沒有參與研究的科學家都注意到，新物種包含了一些迥異的解剖特徵，包括較像現代人的下顎、牙齒和腳，這就證明應該被歸爲人屬的人亞族物種，而非生活在320萬年前的南方古猿屬，也就是著名的露西(Lucy)所在的屬。新發現物種標本中的手令一些科學家想起了此前已知最早的能人(Homo habilis)標本，而能人看來是最早開始製作工具的物種。

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.

在週三的一場新聞發佈會上，論文資深作者、威斯康星大學麥迪遜分校(University of Wisconsin, Madison)的約翰·霍克斯(John Hawks)說，該物種“不像我們之前見過的任何物種”，指出該物種在非常苗條的身體上有一個很小的頭骨，以及只有現代人腦殼三分之一大小的大腦。他說，一個普通的納勒迪人身高大概5尺（約合1.51米），體重將近100磅（約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.”

伯傑研究團隊成員、英格蘭肯特大學(University of Kent)的翠西·凱威爾(Tracy Kivell)說， 讓她十分驚訝的是，納勒迪人“有極度彎曲的手指，比任何早期人亞族物種都要彎，清楚地表明瞭他們的攀爬能力。”

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.

紐約城市大學李曼學院的威廉·哈考特-史密斯(William Harcourt-Smith)亦是美國自然歷史博物館的研究員，他負責對該新物種的腳展開研究，他說他們的腳“與現代人的雙腳基本上沒分別。”結合他們的長腿，他認爲納勒迪人完全適合長時間直立行走。

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.

在期刊隨附的一篇評論中，倫敦自然歷史博物館(Natural History Museum in London)的古人類學家克里斯·斯特林格(Chris Stringer)發現，新物種大致上與前蘇聯格魯吉亞共和國境內的德馬尼西(Dmanisi)發現的化石近似，後者能追溯到約180萬年前。格魯吉亞標本通常被歸類爲早期直立人(Homo erectus)的一個變種。