Human technology

A prehistoric eruption has helped recalibrate our timeline of human origins in Africa

In the late 1960s, archaeologists discovered a set of familiar bones in Ethiopia: a skull bone, a lower jaw and parts of a torso.

This collection is known as Omo 1 and, at 200,000 years old, it is believed to be one of the oldest human remains ever discovered. Now, a new study claims the bones are at least 33,000 years older than originally thought.

This period is key to understanding how humans evolved in Africa, according to Tim White, a professor of integrative biology at the University of California, Berkeley.

“Building that time frame requires accurate dating techniques,” he said. “Unfortunately, we’re just beyond the range of radiocarbon or C-14 dating, so you have to use other techniques to determine the true age of these fossils.”

One such technique involves determining the age of the environment where the bones were found – in the case of Omo 1, a layer of volcanic ash.

“There has been a bit of controversy because the way Omo 1 was first dated was using a layer of ash that would have been found just below,” said Céline Vidal, a volcanologist at the University of Cambridge. “But it wasn’t found where the fossils were found. It was found a bit further afield.”

Vidal said the ash layer above Omo 1 was flour-thin, which is difficult for scientists to date.

But in a new analysis, Vidal and his colleagues found that volcanic ash had the same chemical fingerprint as a massive volcanic eruption more than 233,000 years ago.

“It’s based on the principle that every eruption has a unique chemical fingerprint, a unique chemical signature,” she said. “So when it is possible to analyze a signature of an ash layer and if it correlates with the signature of an ash layer elsewhere and we know the age of one of the deposits, then we can indirectly guess the age of the deposits with which it is correlated.”

As Omo 1 was under this ash, Vidal believes the bones are at least 33,000 years older than previously thought.

The study, published in the journal Nature, raises many questions about Homo sapiens at that time.

“When did these peoples develop from Africa? What is their technology? What was the environment they occupied? What was Africa like at that time? It all depends on a strong geological framework but mostly of a timeline,” White said. noted. “And that’s what this new work has provided for one of the most complete skeletons of this period.”

In other words, if these human remains are much older than we thought, so could human history.

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