Sunday, February 20, 2022

Way Older Than Previously Thought

 From Smithsonian:

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.”

The findings, published this week in the journal Nature, show that Omo I had to be older than the layer that later fell from the sky to rest atop her remains, but they don’t reveal her maximum age. It may later be possible to determine the oldest possible date for Omo I if the team can similarly identify another volcanic layer from below the fossil. (Read more.)


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