Ape that lived in Europe 7 million years ago could be human ancestor, controversial study suggests – Washington Post

In 1944, German soldiersconstructing a bunker in Greece uncovered afossilized jawbone. The specimen was in poor shape, just a curve of mandible with its teeth mostly chipped away. It was considered to be a specimen that nobody really knew what to do with, said paleobiologist David R. Begun,a professor at the University of Toronto. But a new analysis of this broken jaw revealed that the bone is about7 million years old. The jawalso has some humanlike characteristics, he says.

Begun and his colleagues say the fossil could represent the oldest known human ancestor. They further suggest that the fossil means our ancestors diverged from apes in Southern Europe not Africa.

Both are bold and highly disputed claims. But the fossil itself is a rare specimen ofan ape from around the time of the last common ancestor of chimpanzees and humans.

Ina pair of reportspublished Monday in the journal PLOS One, the scientists describe the fossil and the possible savanna environment in which the specieslived. Theresearchers claim that the Eastern Mediterranean could just as likely be the location of ape and human diversification, as well as human ancestororigins, as tropical Africa.

Other experts on human prehistory disagree, pointing to extensive fossil evidence that hominins, meaning non-ape humans and their ancestors, originated in Africa and migrated north.

David Begun has repeatedly proposed that the African ape and human clade arose in Europe and that gorillas, chimps and humans arose from an early European member of this group that migrated into Africa, said Jay Kelley, a paleontologist at Arizona State University's Institute of Human Origins. This 'back into Africa' scenario has garnered few if any adherents. The near consensus, Kelley said in an email, is that the hominin lineage arose in Africa.

The jaw in question belonged to a primate that anthropologists had previously namedGraecopithecus freybergi.In the new study, researchers at theUniversity of Tbingen in Germanyused a CT scan to peer insidethe jaw. They also analyzed an upper premolar tooth from another primate, dated via paleomagnetic studies to 7.2 million years ago, discovered in the Balkans in Bulgaria. The authors of the new studiessuggest that this loose tooth could have come from another member of the same species.

The scans of the jaw showed some similarities with human ancestors.Despite the chipped teeth, the roots buried inthe jawbone remained intact. The canine root was very short, Begun said. The premolar roots were simplified, partly fused.Both of those characteristics we find only in members of human lineage.

For the loose tooth, the thickness of the enamel ruled out other, better-documented ancient apes, the scientists said, such asOuranopithecus. But they could not prove with absolute certainty that the tooth camefrom Graecopithecus freybergi.

I really appreciate having a detailed analysis of the Graecopithecus jaw the only fossil of its genus so far, said Richard Potts, a paleoanthropologist who directs the Smithsonian Institutions Human Origins Program.But I think the principal claim of the main paper goes well beyond the evidence in hand.

Potts, who was not involved in this study, noted that the heyday of ape diversity occurred in Eurasia between 12 and 10 million years ago. This diverse group of primates migrated to lower latitudes namely, Africa and Asia to escape cooling northern temperaturesand more powerful seasonal changes. There was little to support the idea that hominins appeared before leavingEurope.

I don't think it's a strong case for hominin origins in Asia rather than Africa. Possible, yes, said New York University'sSusan C. Antn, a professor of anthropology who was not affiliated with the recent study. But because all of the later hominins are found inAfrica, the simplest explanation, she said, is an African origin.

Kelley questioned the significance of the fused premolar root. Some of the earliest hominins didnt have these fused tooth roots, whereas some of the later hominins did, he said. Given this discrepancy, it's a feature that may have evolved independently in several different lineages, he said.

The evidence that canine root reduction indicates the hominin status of Graeco is also not very convincing, Potts said. Only one canine root was studied. Plus, he said, there's no way to consider the root in the context of the entire tooth the canine crown had snapped off.So theres little basis for accepting the exceptional claim that a 7.2 million year old fossil from Greece is the oldest known human ancestor!

I'm the first to admit that what we have is less than ideal, Begun said. We need better-preserved jaws, and some limb bones to tell us if it was bipedal.The site in urban Athens where the jaw was discovered is now too developedto hunt for fossils.But where the lone tooth was found in the Balkans, to the north across the Aegean Seafrom Athens, ancient rocky outcrops remain.

Begun said he plansto travel to Bulgaria tolook for additional fossils.If you have one tooth, he said, that means there has to be other specimens out there.

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Ape that lived in Europe 7 million years ago could be human ancestor, controversial study suggests - Washington Post