Humans and chimpanzees split from their last common ancestor several hundred thousand years earlier than believed, according to Prof. Böhme and co-authors.
Their findings, published in the journal PLoS ONE, also indicate that the split of the human lineage occurred not in Africa, but in the Eastern Mediterranean.
“Present-day chimpanzees are humans’ nearest living relatives. Where the last chimp-human common ancestor lived, however, is a central and highly debated issue in paleoanthropology,” Prof. Böhme and co-authors said.
“Scientists have assumed up to now that the lineages diverged 5-7 million years ago and that the first pre-humans developed in Eastern Africa.”
“According to the 1994 theory of French paleoanthropologist Yves Coppens, climate change in the region could have played a crucial role.
“Our discovery outlines a new scenario for the beginning of human history,” added co-author Professor David Begun, from the University of Toronto.
The researchers analyzed two known specimens of Graecopithecus freybergi: a lower jaw from Pyrgos, Greece, and an upper premolar from Azmaka, Bulgaria.
Using computer tomography, they visualized the internal structures of the specimens and demonstrated that the roots of premolars are widely fused.
“While great apes typically have two or three separate and diverging roots, the roots of Graecopithecus converge and are partially fused — a feature that is characteristic of modern humans, early humans and several pre-humans including Ardipithecus and Australopithecus,” Prof. Böhme said.
“The lower jaw of Graecopithecus freybergi has additional dental root features, suggesting that the species might belong to the pre-human lineage.”
“We were surprised by our results, as pre-humans were previously known only from sub-Saharan Africa,” said co-author Jochen Fuss, a PhD student at the University of Tübingen.
“Furthermore, Graecopithecus freybergi is several hundred thousand years older than the oldest potential pre-human from Africa, the 6-7 million-year-old Sahelanthropus tchadensis from Chad.”
The team dated the sedimentary sequence of the Graecopithecus fossil sites in Greece and Bulgaria with physical methods and got a nearly synchronous age for both fossils: 7.24 and 7.175 million years before present.
Questioning the "out of Africa" anthropological orthodoxy is racism. :-) To read more, click here.