DISCOVERY OF OLDEST HOMO SAPIENS SHAKES UP THEORIES OF HUMAN ORIGINS.

Homo sapiens bones have been unearthed in Morocco dating back 300,000 years, challenging the idea that we first evolved in East Africa 200,000 years ago.

A cache of newly discovered fossils unearthed from a disused mine in Morocco has cast doubt upon the commonly held belief that Homo sapiens arose in East Africa 200,000 years ago.

The remains of several individuals, along with a collection of stone tools and animal bones, were found at the Jebel Irhoud archaeological site in Morocco. Using state-of-the-art dating techniques, a team at the Max Planck Institute in Leipzig estimates that the bones date back about 300,000 years, making them the oldest securely dated fossil evidence of our own species.

Previously, the oldest Homo sapiens fossils were found in Omo Kibish in Ethiopia and were estimated to be 195,000 years old. Until now, it was widely believed that all humans descended from a population that lived in East Africa around 200,000 years ago.

“We used to think that there was a cradle of mankind 200,000 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,” said researcher Prof Jean-Jacques Hublin.

The team used highly accurate 3D scans and statistical shape analysis based on hundreds of measurements to show that the facial shape of the Jebel Irhoud fossils is almost indistinguishable from that of modern humans. However, they found that the craniums of the Jebel Irhoud fossils have an elongated braincase – a feature more common in early Homo species.

“The inner shape of the braincase reflects the shape of the brain,” said researcher Dr Philipp Gunz. “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.”

“North Africa has long been neglected in the debates surrounding the origin of our species,” said researcher Abdelouahed Ben-Ncer. “The spectacular discoveries from Jebel Irhoud demonstrate the tight connections of the Maghreb [a region of northwestern Africa] with the rest of the African continent at the time of Homo sapiens’ emergence.”

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Expert comment -Chris Stringer and Julia Galway-Witham

Until recently, most experts thought that modern humans had evolved between 150,000 and 200,000 years ago, with the earliest known fossils found at sites in Ethiopia. It was not until new research was published in Nature in June that we have compelling fossil evidence to suggest that the evolution of our lineage is deeper rooted than previously thought, and not confined to East Africa.

Now dated to about 300,000 years ago, the assemblage of human fossils from Jebel Irhoud represents the earliest known examples of Homo sapiens. However, it is not yet known how peripheral the Irhoud population would have been. Populations of H. heidelbergensis, H. rhodesiensis and H. naledi were living contemporaneously in central and southern Africa and it is likely that there were other populations of early H. sapiens elsewhere in Africa at this time. In light of this new chronology, and combined with the mixture of traits in the Irhoud fossils, it’s possible that still earlier fossils from sites in Morocco and Tanzania might represent an even more primitive form of our species.

While molecular evidence suggests the ancestors of modern humans may have diverged from Neanderthals at least 500,000 years ago, and early Neanderthals from 430,000 years ago have been identified from Sima de los Huesos in Spain, equivalent specimens from the modern human lineage had yet to be identified. The Irhoud fossils are contenders for this position. The clear anatomical differences between the Irhoud and Sima specimens suggest the two lineages were diverging rapidly, even though they lie relatively close to the date of their projected common ancestor. Intriguingly, both the Sima and Irhoud fossils do not display the full suite of features present in later representatives of their respective species. This has interesting implications for understanding how and in what order these anatomical features evolved over the last half a million years.

Edited by Jason Goodyer in "BBC Focus", UK, Summer 2017, excerpts pp. 10-11. Digitized, adapted and illustrated to be posted by Leopoldo Costa.

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