Based on an analysis of 7.2-million-year-old fossil remains, a new study claims that the split of the common lineage of great apes and humans probably occurred in Europe and not — as customarily assumed — in Africa. The findings, published in two papers in the journal PLOS ONE, thus outline a new scenario for the beginning of human history.
The common lineage of great apes and humans split several hundred thousand years earlier than assumed until now, according to the research. The research team analysed the two known specimens of the fossil hominid Graecopithecus freybergi — a lower jaw from Greece and an upper premolar from Bulgaria.
Using computer tomography, they visualised the internal structures of the fossils 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,” said Madelaine Bohme from Senckenberg Centre for Human Evolution and Palaeoenvironment at the University of Tubingen in Germany.
The lower jaw, nicknamed ‘El Graeco’ by the scientists, has additional dental root features, suggesting that the species Graecopithecus freybergi 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 Jochen Fuss from the University of Tubingen.
Furthermore, Graecopithecus is several hundred thousand years older than the oldest potential pre-human from Africa, the six to seven million year old Sahelanthropus from Chad.
The research 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 old.
“It is at the beginning of the Messinian, an age that ends with the complete desiccation of the Mediterranean Sea,” Bohme said. “This dating allows us to move the human-chimpanzee split into the Mediterranean area,” said co-author of this study, David Begun, Professor at University of Toronto, Canada.
Present-day chimpanzees are humans’ nearest living relatives. Where the last chimp-human common ancestor lived is a central and highly debated issue in palaeoanthropology.
Researchers have assumed up to now that the lineages diverged five to seven million years ago and that the first pre-humans evolved in Africa. The beginning of human history could be different if claims of the new study are to be believed — and validated later.