Human Fossils Dated to 195,000 Years

摘要：
    对化石的深入分析使现代人的历史可以追溯到19.5万年以前。
    Researchers determined¹ that the specimens³ are around 195,000 years old.

    对化石的深入分析使现代人的历史可以追溯到19.5万年以前。通过对1967年于非洲埃塞俄比亚出土的人类骨骼化石进行新一轮的分析研究，科学家日前确定，这些化石的历史比先前认为的还要早大约6.5万年。这一结论说明，现代人类的化石记录可以追溯到大约20万年以前。

    据美联社1月16日报道，科学家们认为，这些化石大约有19.5万年的历史，比人们以前推测的还要早6.5万年。遗传学研究曾推测，智人（即现代人）应起源于大约20万年以前，而这项新的研究结果恰好与遗传学研究结果相一致。

    这些智人遗骨化石是于1967年在埃塞俄比亚的奥莫河（omo）附近被发掘出来的。出土的包括一些头骨和躯干骨的化石残片。当时，科学家将这些化石称为现代智人（Homo sapiens）化石，并将其历史暂定为13万年。

    日前，美国纽约Stony⁴ Brook⁵大学的约翰·弗利格尔和他的同事通过考察化石出土地点，并利用更先进的时间测定仪器分析当地的地质结构和岩石标本，他们发现这些化石应该具有19.5万年的历史。（其中允许有5000 年的误差）

    科学家认为，重新修订的时间使“现代人起源于非洲”这一理论更具说服力。日期的提前让这些早期现代人有更充足的时间发展他们的文化属性，使他们从非洲大陆分散到亚欧各地。报道说，在此之前，被认为是最古老的智人遗骨化石是由美国科学家1997年在埃塞俄比亚发现的，该化石的历史约为16万年。

    一个多世纪以来，智人的起源是人类进化研究中根本性的重大问题。许多科学家认为，智人与人类更原始的祖先一样，发源于非洲。但也有科学家提出，智人是在世界不同地区分别发展起来的。

    A new analysis of bones unearthed⁶ nearly 40 years ago in Ethiopia has pushed the fossil record of modern humans back to nearly 200,000 years ago perhaps close to the dawn of the species.

    Researchers determined that the specimens are around 195,000 years old. Previously⁷, the oldest known fossils of Homo sapiens were Ethiopian skulls⁹ dated to about 160,000 years ago.

    Genetic¹⁰ studies estimate that Homo sapiens arose about 200,000 years ago, so the new research brings the fossil record more in line with that, said John Fleagle of Stony Brook University in New York, an author of the study.

    The fossils were found in 1967 near the Omo River in southwestern Ethiopia. One location yielded Omo I, which includes part of a skull⁸ plus skeletal bones. Another site produced Omo II, which has more of a skull but no skeletal bones. Neither specimen² has a complete face.

    Although Omo II shows more primitive¹¹ characteristics than Omo I, scientists called both specimens Homo sapiens and assigned a tentative age of 130,000 years.

    Now, after visiting the discovery sites, analyzing¹² their geology and testing rock samples with more modern dating techniques, Fleagle and colleagues report in Thursday's issue of the journal Nature that both specimens are 195,000 years old, give or take 5,000 years.

    Fleagle said the more primitive traits of Omo II may mean the two specimens came from different but overlapping¹³ Homo sapiens populations, or that they just represent natural variation within a single population.

    To find the age of the skulls, the researchers determined that volcanic¹⁴ rock lying just below the sediment¹⁵ that contained the fossils was about 196,000 years old. They then found evidence that the fossil-bearing sediment was deposited soon after that time.

    Paul Renne, director of the Berkeley Geochronology Center, which specializes in dating rocks, said the researchers made "a reasonably good argument" to support their dating of the fossils.

    "It's more likely than not," he said, calling the work "very exciting and important."