A skull found in Dmanisi, Georgia, by anthropologists from the University of Zurich, is the best-preserved fossil find yet from the early era of our genus and has the potential to rewrite evolutionary history.
Named ‘skull 5’ after being the fifth ancient skull to be discovered in Dmanisi, it has the largest face, the most massively built jaw and teeth and the smallest brain within the Dmanisi group – all the other skulls were found in the same location and date from the same time period. According to the Swiss scientists, the discovery suggests that all Homo species were once one.
Until now it was believed that different characteristics among the Homo fossils, including those from Homo habilis, Homo rudolfensis and Homo erectus, showed they were distinct, different species. However, this research casts this theory into doubt.
Scientists from the Anthropological Institute and Museum in Zurich say Skull 5 indicates that rather than several specialised Homo species, a single Homo species that was able to cope with a variety of ecosystems emerged from Africa some two million years ago.
In other words, the individuals simply looked different to each other but belonged to the same species – according to the researchers, the differences between the Dmanisi fossils are no more pronounced than those between five modern humans. If this is the case, researchers will be forced to rewrite the classification system for early human ancestors.
“'The Dmanisi finds look quite different from one another, so it's tempting to publish them as different species,” said Christoph Zollikofer from the Swiss museum. “Yet we know that these individuals came from the same location and the same geological time, so they could, in principle, represent a single population of a single species.”
The discovery suggests that early, diverse Homo fossils with their origins in Africa, represent variation among members of a single, evolving lineage - most appropriately Homo erectus.