7.2-million-year-old pre-human fossils challenge modern human evolution theory

A jawbone discovered by German troops in Athens during the Second World War could be evidence that apes and humans diverged 200,000 years earlier than the current theory says.

Chimpanzees and bonobos are the nearest known relatives to humans, sharing 99 per cent of our DNA. It's believed that we split between five and seven million years ago. 

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However, researchers analyzing two fossils — a jawbone from a German museum and an upper premolar from a collection in Bulgaria — concluded their ages to be roughly 7.2 million years, and belonging to a pre-human.

But there's another significant finding: that human split occurred in the eastern Mediterranean and not Africa, as it is believed.

Pre-human roots

The researchers came to the conclusion after analyzing the roots of the teeth preserved in the fossils, named Graecopithecus freybergi.

"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," Madelaine Bohme from the Senckenberg Centre for Human Evolution and Palaeoenvironment at the University of Tubingen explained in a statement.

This came as a bit of a surprise to the researchers, who used computer tomography to examine the interior of the roots, which were, unlike the external teeth, in pristine condition. This method allowed a more accurate dating than techniques used in other fossil findings, such as Australopithecus and Ardipithecus, two of the oldest known pre-humans.

"It's an important advance," David Begun, a paleoanthropologist from the University of Toronto and co-author of the paper that appeared in PLoS One, told CBC News. "Because it's not so much that it's older — because it's not hugely older — but that the date is really a good, solid date."

Begun also noted that, because Graecopithecus is so old and no limb bones were found, it's not known whether it was bipedal or used arms and legs to move around.

Skepticism is likely

This conclusion is likely to draw some criticism: the divergence of apes and humans is believed to have taken place in Africa roughly six million years ago. Suggesting instead that it occurred in Europe is not a popular theory.

Begun said that he's already heard some skepticism about the group's findings. 

"People who are skeptical … will say that it evolved in parallel," Begun said. "But that's a special pleading for people who just can't believe … that chimps and humans could have diverged outside of Africa. But there's no reason to start with that premise at all."

A second paper published in PLoS One highlights the geological evidence to support a climate similar to present-day Africa. Giraffes, antelopes and even rhinoceros lived in that region for some time.

The drought-like conditions may have played a role in the splitting of chimps and humans. Changing conditions may have forced the animals and pre-humans toward the equator, to Africa.

Before this finding, the oldest known pre-human was Sahelanthropus from Chad.