A team of archaeologists found fossil bones of Homo sapiens along with stone tools and animal bones at Jebel Irhoud, Morocco dated back to about 300,000 years ago and the oldest ever securely dated fossil evidence of humans, almost 100,000 years earlier than the previous oldest Homo sapiens fossils ever found.
The fossil find by an international research team led by Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology (Leipzig, Germany) and Abdelouahed Ben-Ncer of the National Institute for Archaeology and Heritage (INSAP, Rabat, Morocco) reveal a complex evolutionary history of mankind involving the entire African continent.
Since both genetic data and fossil remains point to an African origin of our own species, Homo sapiens, until now, most researchers believed that all humans living today descended from a population that lived in East Africa around 200,000 years ago. Now it would be dated back by another 100,000 years.
“We used to think that there was a cradle of mankind 200 thousand years ago in east Africa, but our new data reveal that Homo sapiens spread across the entire African continent around 300,000 years ago. Long before the out-of-Africa dispersal of Homo sapiens, there was dispersal within Africa,” says palaeoanthropologist Jean-Jacques Hublin.
The finds from the Moroccan site of Jebel Irhoud has been well known since the 1960s for its human fossils and the Middle Stone Age artefacts. To date them accurately, researchers used the thermoluminescence dating method on heated flints found in the deposits, which yielded an age of approximately 300,000 years ago.
“Well dated sites of this age are exceptionally rare in Africa, but we were fortunate that so many of the Jebel Irhoud flint artefacts had been heated in the past,” says geochronology expert Daniel Richter of the Max Planck Institute in Leipzig (Germany).
The crania of modern humans clearly distinguish us from our ancestors: a small and gracile face, and globular braincase. The fossils from Jebel Irhoud display a modern-looking face and teeth, and a large but more archaic-looking braincase.
Hublin and his team used state-of-the-art micro computed tomographic scans and statistical shape analysis based on hundreds of 3D measurements to show that the facial shape of the Jebel Irhoud fossils is almost indistinguishable from that of modern humans.
The only difference is that the Jebel Irhoud crania retain a rather elongated archaic shape of the braincase. “The inner shape of the braincase reflects the shape of the brain,” explains palaeoanthropologist Philipp Gunz from the Max Planck Institute for Evolutionary Anthropology in Leipzig.
“Our findings suggest that modern human facial morphology was established early on in the history of our species, and that brain shape, and possibly brain function, evolved within the Homo sapiens lineage,” he says.
The findings were published in the June 8th issue of the journal Nature.