Scientists have uncovered yet another tiny piece of the puzzle of our origins. Findings published online this week by the Proceedings of the National Academy of Sciences describe a lower jawbone that they say is the earliest evidence of anatomically modern humans in Europe.

Three Romanian spelunkers recovered the mandible in February 2002 at a site in the southwestern Carpathian Mountains known as Pestera cu Oase, or the "Cave with Bones." The cave also housed other fossils including a facial skeleton, a temporal bone and a partial braincase that are currently undergoing examination. Radiocarbon analysis dates the jawbone to between 34,000 and 36,000 years ago, report Erik Trinkaus of Washington University and his colleagues. "The jawbone is the oldest directly dated modern human fossil," Trinkaus remarks. "Taken together, the material is the first that securely documents what modern humans looked like when they spread into Europe. Although we call them 'modern humans,' they were not fully modern in the sense that we think of living people."

According to the researchers, the jawbone provides perspective on the emergence of anatomically modern humans in the northwestern Old World, which is a far from simple story. The two most prominent theories are the Out of Africa model, which states that Homo sapiens arose in Africa between 150,000 and 200,000 years ago and went on to replace archaic hominids such as the Neandertals, and the multiregional evolution model, which holds that modern humans instead emerged from these archaic populations across the Old World. The newly characterized jawbone has many features in common with remains of other early modern humans found at sites in Africa, the Middle East and later European locales, but the large face size inferred from the jaw also hints at the retention of some archaic characteristics. Notes Trinkaus, "the specimens suggest that there have been clear changes in human anatomy since then."

In 1999, Trinkaus and his colleagues reported on the discovery of a 25,000-year-old skeleton from Portugal said to share a mix of Neandertal and modern characteristics. The Pestera cu Oase finds, he adds, "are also fully compatible with the blending of modern human and Neandertal populations."