Humans may have originated in Europe – and not in Africa – much earlier than previously thought, according to the study of a 7.2 million-year-old pre-human fossil that could potentially rewrite the history of evolution.
According to an international research team, the common lineage of great apes and humans split several hundred thousand years earlier than assumed.
The researchers, led by Madelaine Bohme from the University of Tubingen in Germany and Nikolai Spassov from the Bulgarian Academy of Sciences, studied two fossils of Graecopithecus freybergi with state-of-the-art methods and came to the conclusion that they belong to pre-humans.
The findings, published in the journal PLOS ONE, further indicate that the split of the human lineage occurred in the Eastern Mediterranean and not – as customarily assumed – in Africa.
Present-day chimpanzees are humans' nearest living relatives. Where the last chimp-human common ancestor lived is a central and highly debated issue.
Researchers have assumed up to now that the lineages diverged five to seven million years ago and that the first pre-humans developed in Africa.
According to the 1994 theory of French researcher Yves Coppens, climate change in Eastern Africa could have played a crucial role.
The new research now outlines a new scenario for the beginning of human history.
The 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 Bohme.
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, a PhD student at University of Tubingen.
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 before present.
“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 Professor David Begun, a University of Toronto.
Researchers demonstrated that the North African Sahara desert originated more than seven million years ago. The team concluded this based on geological analyses of the sediments in which the two fossils were found.
Although geographically distant from the Sahara, the red-coloured silts are very fine-grained and could be classified as desert dust.
“These data document for the first time a spreading Sahara 7.2 million years ago, whose desert storms transported red, salty dusts to the north coast of the Mediterranean Sea in its then form,” researchers said.
“The incipient formation of a desert in North Africa more than seven million years ago and the spread of savannahs in Southern Europe may have played a central role in the splitting of the human and chimpanzee lineages,” said Bohme.