Wolfgang Gerber / University of Tübingen
Analysis of 7.2 million year old remains in Europe and the areas surrounding the sites has led an international research team to suggest two key things: the origin of humankind may be in Europe and not in Africa, and environmental changes may have been the driving force for human-chimp divergence, according to two studies published together today.
The two studies, both published in PLOS ONE:
- The dental study examines specimens of a lower jaw from Greece and an upper premolar from Bulgaria from a relatively new species called Graecopithecus freybergi and concluded they most likely belong to pre-humans called hominin. Both fossils were dated at about 7.2 million years before present — several hundred thousand years older than the (previously oldest) potential pre-human found in Chad.
- The environmental study looks at the area surrounding the fossil finds and demonstrates evidence of severe environmental changes and concluded that a savannah biome formed in those areas of Europe around the same time as the Graecopithecus lived.
What it means: Where the last chimp-human common ancestor lived is a highly debated issue in palaeoanthropology. "This dating allows us to move the human-chimpanzee split into the Mediterranean area," David Begun, co-author of the study and a University of Toronto paleoanthropologist, said.
Yes, but: These studies do not prove the fossils are pre-humans (since there are not large enough bones) or that climate change triggered the divergence of humans from chimpanzees (just that it occurred at roughly the same time as the graecopithecus lived). Some researchers remain unconvinced and believe the fossils are from apes that lived in Europe at the time.
Details of dental study: Using computer tomography, the team was able to visualize the internal structures of the fossils and demonstrated that the roots of premolars are widely fused and that the lower jaw had additional features normally found in pre-humans.st
"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," according to Madelaine Böhme, head of the international research team and a professor at the University of Tübingen.
Details of the environment study: Taking a geological analysis of the sediments surrounding the fossil finds and using new methodologies to study microscopic fragments of charcoal and plant phytoliths, Böhme said the evidence showed severe droughts and recurring vegetation fires. Begun said climate change may explain why there was a split between human and chimp lineages.
"The transition to hominins probably involved increased terrestriality while still maintaining a dependency on trees," Begun said. "Increased [terrestriality] would theoretically be advantageous in a drier climate with few trees and arboreal resources."
Another perspective: Carol Ward, biological anthropologist at University of Missouri not involved in this study, agrees the studies do not prove pre-humans originated 7.2 million years ago in the Balkans area or that the divergence was due to climate change, but added the studies bring anthropologists closer to answers. Ward also admires the way the studies used advanced technology in new ways to examine fossils closer — such as seeing the internal structure of the roots of the teeth. "These are more weapons in our scientific arsenal," she said.