(USA TODAY) — Digging on a hilltop in the Sahara Desert, scientists have found the most ancient known members of our own species, undermining longstanding ideas about the origins of humanity.
The newfound Homo sapiens fossils — three young adults, one adolescent and a child of 7 or 8 — date back roughly 300,000 years, says a study in this week’s Nature. The next-oldest fossils of Homo sapiens, the scientific name for humans, are about 200,000 years old.
The 200,000-year-old fossils were found in eastern Africa, sometimes called the “Garden of Eden” for its supposedly pivotal role as the birthplace of humanity. But the new fossils are from Morocco in far northern Africa, supporting the theory that the evolution of modern humans was a piecemeal affair that played out across the continent.
“There is no Garden of Eden in Africa,” said Jean-Jacques Hublin, co-author of two new studies describing the fossils and a paleontologist at Germany’s Max Planck Institute for Evolutionary Anthropology. “Or if there is a Garden of Eden, it’s … the size of Africa.”
The new finds confirm “modern humans do not suddenly appear like the Big Bang, with all the bells and whistles that we associate with modern humans,” agrees paleoanthropologist Bernard Wood of George Washington University, who was not associated with the study.
The fossils were excavated at a site called Jebel Irhoud, where similar fossils were unearthed in the 1960s and assigned an age of 40,000 years. Hublin’s team returned to the site in 2004 hoping to clarify that date — and instead stumbled upon more fossils. They also applied new dating methods, which pushed back the age of all the fossils to a stunning 300,000 years.
The trove of fossils is a snapshot of a species in transition. The Irhoud people had more elongated, primitive-looking skulls than current humans. But these ancient people had small faces and small chins much like ours, and their teeth look like ours, too. The new date for the fossils suggests some elements of Homo sapiens anatomy developed a more modern appearance much earlier than thought, says Adam Van Arsdale of Wellesley College, who was not involved with the study.
This mix of archaic and modern features supports the theory that Homo sapiens didn’t burst onto the African scene fully formed. Instead, the earliest people had a mix of advanced and primitive characteristics, and over time and across the continent, Homo sapiens evolved into the humans of today, Hublin said.
Though the new fossils have features that don’t seem entirely human, such as a low skull, “I think we have a good instance of early Homo sapiens from Irhoud,” says Rick Potts, head of the Smithsonian Institution’s Human Origins Program, who was also not part of the study team. But he says the idea that Homo sapiens “was assembled gradually” is “by no means a slam dunk” and needs to be shored up by more fossils from around Africa.
Artifacts found with the fossils suggest that activities typical of modern humans also emerged by 300,000 years ago, says paleoanthropologist Alison Brooks of George Washington University. Alongside the Irhoud fossils, researchers found gazelle bones marked with stone tools, the remnants of ancient fires and sharpened pieces of flint probably used as spear points. The study’s authors say the site, which was once a cave, may have been used as a hunting camp.
The new date for the Irhoud skeletons “changes a lot,” Brooks says. “It pushes (the fossils) into a fairly unknown time range, but one that is clearly very important for the evolution of our species.”
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