At a remote region in southwestern Ethiopia, the Omo River and its long-vanished tributaries have laid bare rugged bluffs and hillsides, exposing a la

East Africa’s Oldest Modern Human Fossil Is Way Older Than Previously Thought

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2022-01-14 01:30:07

At a remote region in southwestern Ethiopia, the Omo River and its long-vanished tributaries have laid bare rugged bluffs and hillsides, exposing a layer cake of ancient sediments and the trapped remains of early humans. Before the Covid pandemic, Céline Vidal and colleagues journeyed to this site known as the Kibish Formation to work in scorching temperatures up to 110 degrees Fahrenheit, picking through the ashes of ancient volcanic eruptions to learn more about some of the oldest members of our species.

“It was an adventure,” says Vidal, a volcanologist at the University of Cambridge, who studies how ancient eruptions impacted climate and civilizations. “This is the part of science that online life isn’t ever going to replace.”

One of the reasons Vidal and colleagues came to the site was to learn about Omo I, one of the oldest known examples of Homo sapiens. Using geochemical clues to match the layer of volcanic ash blanketing the fossil to a specific volcanic eruption, they discovered Omo I is 36,000 years older than previously believed. Ash from an enormous eruption of the Ethiopian Rift’s Shala volcano was put down atop the sediment layer containing the Omo I fossil approximately 233,000 years ago, which means that Omo I and her kind lived here at least that long ago.

“Each eruption has a unique geochemical composition, a kind of fingerprint which we can use to try to figure out exactly which eruption on the Ethiopian Rift would have created a layer of volcanic ash,” Vidal explains. “We found a match for the ash layer that covers the fossils, so we know which eruption produced that ash and the age of that eruption.”