A research team co-directed by Erik Trinkaus, Ph.D., the Mary Tileston Hemenway Professor of Anthropology in Arts & Sciences, has dated a human jawbone from a Romanian bear hibernation cave to between 34,000-36,000 years ago.
That makes it the earliest known modern human fossil found in Europe.
Other human bones from the same cave — a temporal bone, a facial skeleton and a partial braincase — are still undergoing analysis, but are likely to be the same age.
The jawbone was found in February 2002 in Pestera cu Oase — the “Cave With Bones” — in the southwestern Carpathian Mountains. The other bones were found in June 2003.
The results on the jawbone were published in the Sept. 30 Proceedings of the National Academy of Sciences. A report on the other bones will appear in an upcoming issue of the Journal of Human Evolution.
The finds should shed much-needed light on early modern human biology.
“This jawbone is the oldest directly dated modern human fossil,” Trinkaus said. “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.”
To determine the fossils’ implications for human evolution, Trinkaus and his colleagues performed radiocarbon dating of the jawbone and a comparative anatomical analysis. Its age places it in the period during which early modern humans overlapped with late-surviving Neandertals in Europe.
Most of their anatomical characteristics are similar to those of other early modern humans found at sites in Africa, the Middle East and later in Europe, but certain features — such as the unusual molar size and proportions — indicate their archaic human origins and a possible Neandertal connection.
The researchers documented that these early modern humans retained some archaic characteristics, possibly through interbreeding with Neandertals. Nevertheless, because few well-dated remains from this period have been found, the fossil remains should help fill in an important phase in modern human emergence.
“The specimens suggest that there have been clear changes in human anatomy since then,” Trinkaus said. “The bones are also fully compatible with the blending of modern human and Neandertal populations.
“Not only is the face very large, but so are the jaws and the teeth, particularly the wisdom teeth. In the human fossil record, you have to go back a half-million years to find a specimen that has bigger wisdom teeth.”
The jawbone was found by three Romanian cavers, who contacted Oana Moldovan, director of the Institutul de Speologie, a cave research institute in Cluj, Romania. Moldovan in turn, recognizing the importance of the jawbone, contacted Trinkaus.
The two met in Europe in May 2002, and Trinkaus brought the jawbone temporarily to the University for analysis. Trinkaus, Moldovan, the cavers and Ricardo Rodrigo, a Portuguese archaeologist, returned to the cave in June 2003 to produce a map and survey the cave’s surface.
In the process, the cavers and Rodrigo found the facial skeleton, temporal bone and the other pieces.
Since then, Trinkaus and Moldovan have assembled an international team to document and excavate the cave and analyze the material after it is removed. The cave was primarily used for bear hibernation.
It is not known how the human bones got into the cave, but Trinkaus said one possibility is that early humans used it as a mortuary for the ritual disposal of human bodies. Some bear bones in the cave were rearranged by humans, documenting past human activities.
“The jaw was originally found sitting by itself; the material this summer was found mixed up with bear bones,” Trinkaus said. “After they found the face, they collected everything on the surface that might be human, packaged it up and brought it out of the cave. Some of the pieces that they carried out of the cave are, in fact, bear.
“We know that more of the skull is in the same place, but it was buried or not recognized at the time.”
The team plans to return to Romania this summer to continue the analysis of the cave and its contents.
To read the report on the jawbone, go online to pnas.org.