经济学人下载:你,似曾相识

Human evolution
人类的进化

You look familiar
你，似曾相识

Another piece of humanity’s family tree is fitted into place
确定另一支人类谱系

THE opening scene of Mel Brooks’s film “History of the World: Part One” dispenses with human origins in one line: “And the ape stood, and became man.” Would that it were that easy for palaeontologists to sort out. The transition to humanity is generally agreed to have occurred between Australopithecus, a genus of small-brained, bipedal primates whose most famous member is a fossil nicknamed “Lucy”, and the big-brained species Homo erectus. But pinning down when precisely this took place, and which of the various australopithecine species were involved, has been challenging. Now the most human-like australopithecine found to date is clarifying things—and staking a claim to be the species from which early humans evolved.

梅尔布鲁克斯的电影“世界历史：第一部”一开场就用一句台词概括了人类的起源：“猿猴站立起来了，然后变成了人”。对古生物学家来说，（人类的起源）要是真能如此解释，那也未免太容易了。人们普遍认为，人类是在南猿（Australopithecus）,（一种脑量小，靠两脚行走的灵长类动物。其最有名的成员是一个外号叫“露西”的化石)和直立猿人（Homo erectus）（一种脑量大的物种）之间完成人类进化过渡的。但至于这段过渡期确切发生在什么时候，又属于众多南猿物种的哪一分支，人们众说纷纭。而目前发现的与人类长得最像的南猿，让一切变得清晰起来，同时，它也被确定是后来进化为早期人类的物种。

Fossils of the new species, Australopithecus sediba, were discovered in 2008 in a cave in South Africa. Initial research, led by Lee Berger of the University of the Witwatersrand, in Johannesburg, concluded that the species came too late in the fossil record to be the ancestor of the Homo lineage. This week, however, a range of new research into sediba, again led by Dr Berger, has been published in Science. These studies conclude that sediba did in fact predate Homo erectus and, moreover, that parts of its anatomy are surprisingly similar to modern man.

新发现的物种化石---南猿源泉种（Australopithecus sediba）于2008年在南非一个山洞中被发现。约翰内斯堡的威特沃特斯兰德大学教授Lee Berger，带领的研究团队经初步研究发现，新物种是化石史上最接近猿人谱系（Homo lineage）的祖先。本周，科学杂志发表了 Berger博士对源泉种的一系列新发现，称源泉种实际上要早于直立猿人，并且其结构的某些部分与现代人也极为相似。

The fossils examined in the Science papers are of an adolescent boy and an adult woman. They are well preserved, and encased in sediments that allow uncommonly precise dating. They lived 1.977m years ago, predating the appearance of Homo erectus by 77,000 years. The period is an especially muddled one for palaeontology, being full of fragmentary fossils that are difficult to assign either to Homo or to Australopithecus. The sediba fossils, by contrast, have some of the most complete features in the early human record.

“科学”杂志发表的论文研究的化石对象，一个是少年，一个是成年女子。这两具化石保存完好，由于是在沉积层出土，所以可以很精确的确定它们的年代。他们生活在197,7000年前，比直立猿人早出现7,7000年。这段时期令古生物学家一直很迷惑不解，因为所有的化石碎片很难确定到底是属于南猿还是直立猿人。相比较而言，源泉种化石具有部分早期人类最完整的特征。