The skull fossil, called Skull 5, is the world’s first completely preserved adult hominid skull from the early Pleistocene.
Unlike other Homo fossils, Skull 5 combines a small braincase with a long face and large teeth. It was discovered alongside the remains of four other early human ancestors, a variety of animal fossils and some stone tools – all of them associated with the same location and time period – which make the find truly unique.
The archaeological site of Dmanisi, located in the Kvemo Kartli region of Georgia about 93 km southwest of the capital Tbilisi, has only been partially excavated so far, but it’s already providing the first opportunity for anthropologists to compare and contrast the physical traits of multiple human ancestors that apparently coincided in the same time and geological space.
“The differences between these Dmanisi fossils are no more pronounced than those between five modern humans or five chimpanzees,” said Dr David Lordkipanidze from the Georgian National Museum in Tbilisi, a lead author of a paper in the journal Science and co-author of a paper published in the Proceedings of the National Academy of Sciences.
Traditionally, researchers have used variation among Homo fossils to define different species. But in light of these new findings, Dr Lordkipanidze and his colleagues suggest that early, diverse Homo fossils, with their origins in Africa, actually represent variation among members of a single, evolving lineage – most appropriately, Homo erectus.
“Had the braincase and the face of Skull 5 been found as separate fossils at different sites in Africa, they might have been attributed to different species,” said Dr Christoph Zollikofer from the Anthropological Institute and Museum in Zurich, Switzerland, a co-author of the Science paper.