Controversial study suggests earliest humans lived in Europe - not Africa

Controversial new research suggests that modern humans evolved from apes in the Eastern Mediterranean — not from ancestors in Africa, as long believed by the majority of scientists.

The researchers' bold, potentially paradigm-shifting claims were published in two studies Tuesday in the journal PLOS One. 

The researchers base their arguments on analysis of two Graecopithecus freybergi ape fossils, a lower jaw found in Greece and an upper premolar found in Bulgaria, dating back 7.24 and 7.175 million years, respectively. 

The team argued that several dental features from these fossils — in particular, partially fused premolar roots on the lower jaw fossil— make a convincing case that the Graecopithecus freybergi is the earliest known human ancestor. Scientists have seen partially fused premolar roots in several fossils throughout the human lineage. 

The lower jaw of the 7.175 million year old Graecopithecus freybergi from what is now metropolitan Athens, Greece.  Wolfgang Gerber, University of Tübingen

"We were surprised by our results, as pre-humans were previously known only from sub-Saharan Africa," doctoral student Jochen Fuss said on behalf of the research team in a statement.

If the fossils mark the earliest moment of humans' differentiation, it would significant change the human origin story. The researchers believe these fossils are several hundred thousand years older than the ancient hominin known as Sahelanthropus, a 6- to 7-million-year-old pre-human which was unearthed in Chad. 

However, the study has been met with widespread skepticism from other experts in the field. 

Critics say that the research is not strong enough to undercut the widespread consensus that evidence shows hominins originated in African and migrated north.

"The idea that hominins (human ancestors, defined largely by upright posture, the predominance of bipedal walking, and small canine teeth in both males and females) first emerged in Europe has little to support it," paleoanthropologist Richard Potts, who leads the Smithsonian Institution's human origins program, told CBS News over email. Potts was not affiliated with the study.

The researchers did little to back up the claim that a "fairly isolated place in southern Europe" could have been home to an ancestor of the African hominin, Potts said. 

He criticized the researchers' claim that the Graeco fossil's canine root reduction clearly indicates the Graeco's status as an early hominin, arguing the researchers did not have enough contextual evidence to draw real conclusions from the single canine root (for instance, there was no canine crown to accompany the root).  

"I really appreciate having a detailed analysis of the Graecopithecus jaw – the only fossil of its genus so far.  But I think the principal claim of the main paper goes well beyond the evidence in hand," Potts said. 

Speaking to The Washington Post, anthropologist Susan C. Antón echoed Potts' skepticism. The long line of later hominins found in Africa suggests "an African origin," Antón, who teaches at New York University, said. 

Jay Kelley, a paleontologist at Arizona State University's Institute of Human Origins, also questioned the researchers' conclusion that the fused premolar roots strongly indicate a connection to hominins. Fused tooth roots are not a constant feature across different hominin fossils, he told The Washington Post. 

The team behind the new research included scientists from Germany, Bulgaria, Greece, Canada, France and Australia.