A fossilised jawbone found poking out of the ground in Ethiopia has set the story of human origins back nearly half a million years to a time when early man shared the vast grassland plains of eastern Africa with a rich variety of prehistoric animals.
Scientists have confirmed that the jawbone belongs to the Homo genus and, at 1.8 million years old, is more than 400,000 years older than the oldest previous fossil of the same group of early humans who eventually gave rise to our own species, Homo sapiens.
The discovery begins to fill in a huge gap in human origins between the primitive “ape man” of Australopithecus afarensis – best known from the Lucy fossil discovered in Ethiopia in 1974 – and the earliest known members of the “human” family, the species Homo habilis or “handy man”.
“The jaw helps to narrow the evolutionary gap between Australopithecus and early Homo. It’s an excellent case of a transitional fossil in a critical time period in human evolution,” said Bill Kimbel, director of the Institute of Human Origins at Arizona State University in Tempe.
The incomplete mandible with teeth was found by graduate student Chalachew Seyoum of the Authority for Research and Conservation of Cultural Heritage in Addis Ababa, who made the discovery while surveying a hill in the Ledi-Geraru area of the Afar region of Ethiopia, where many early human fossils have been unearthed.
“After I had climbed up to the plateau, I saw a premolar coming out of the sediment and it attracted my eye,” Mr Seyoum said, explaining that the jawbone had already become partially exposed by the weathering of the surrounding rock.