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Homo Sapiens Have Been on Earth 100,000 Years Longer Than We Thought

A new discovery rewrites human history.

by Bryson Masse
Jun 7 2017, 5:03pm

Adult mandible found at Jebel Irhoud. Image: Jean-Jacques Hublin/MPI-EVA/Leipzig

A site in Morocco has revealed the fossilized remains of at least five Homo sapiens—a classification that includes us modern living humans—dating back 300,000 years or maybe even longer. These would be the earliest fossils of Homo sapiens ever discovered.

This new research, described in two papers today in Nature, pushes back the timeline of human evolution by thousands of years, and throws a wrench in our current understanding of how the evolution of our species played out across the African continent.

Excavators working on the remaining deposits at Jebel Irhoud. Image: Shannon McPherron, MPI EVA Leipzig

An international team, led by Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology and Abdelouahed Ben-Ncer of the National Institute for Archaeology and Heritage, discovered these fossils at a site called Jebel Irhoud, along with stone tools and animal bones (including gazelles and small mammals).

They found skulls, teeth and long bones from at least five people, using thermoluminescence dating on heated flints to figure out when they were from. By dating them back to 300,000 years ago, they've pushed back our species' origins by 100,000 years.

Some of the Middle Stone Age stone tools from Jebel Irhoud. Image: Mohammed Kamal, MPI EVA Leipzig

Sites like Omo Kibish in Ethiopia had revealed Homo sapiens remains from about 195,000 years ago. But the recent dating of these fossils, located in a cave system about 100 kilometers from Marrakech, suggests that Homo sapiens were more widespread than initially realized: before now, many researchers believed today's humans descended from a group of ancestors living in East Africa some 200,000 years ago.

To the researchers involved in the find, this raises the question: Did Homo sapiens emerge looking like more or less like modern-day humans, or develop slowly and progressively over the last 300,000 years? Hublin told me he believes it's more likely the latter.

"What we see with the discovery of Jebel Irhoud and the new dating is that [early H. sapiens evolution] was a more complicated story and covers a much longer period of time," Hublin told me over the phone. "It involves other regions than East Africa, and maybe more importantly it's not the sort of 'Adamic' emergence of something just like us.

"There is a lot of evolution going on over 300,000 years," he said.

A composite reconstruction of the earliest known Homo sapiens fossils from Jebel Irhoud. Image: Philipp Gunz, MPI EVA Leipzig

Jebel Irhoud has been home to other early hominid finds, in the 1960s. Originally, those fossils were thought to be from a different time period. Initial hypotheses suggested these were Neanderthal or another non-Homo sapiens. But none of the explanations fit the bill.

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"The primary reason why I wanted to re-excavate this site was, first, to obtain a reliable dating, and second, to possibly find more material," said Hublin. "And we were very fortunate because the two expectations have been fulfilled."

The dating of Jebel Irhoud gives us a window into a time when multiple species of hominin shared the same continent. Now we know H. sapiens could have been among them.

Jean-Jacques Hublin pointing at a crushed human skull. Image: Shannon McPherron, MPI EVA Leipzig

While these fossils were similar enough to our present-day selves to be considered modern humans, sharing our delicate cheekbones and flatter face, there were still certain differences. These could highlight how much we've changed over the last 300,000 years.

"[These early humans] still have a rather primitive brain. It's a large brain, but this brain is less globular than our brains. It has a smaller cerebellum," said Hublin. "The modern face and other features evolved very early and the main story was the story of brain evolution."

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