Oldest Human Remains: Controversy Surrounding Omo I’s Actual Age Explained

The oldest human remains unearthed are the Omo I bones unearthed in Ethiopia. However, there was a controversy surrounding its actual age.

Oldest Human Remains

Famed paleoanthropologist Richard Leakey and colleagues found Omo I near the southern Ethiopian town of Kibish in 1967. Originally, scientists dated freshwater mollusk shells found with the skull to conclude that the remains were about 130,000 years old. They also saw from the beginning, quite clearly, that the skull's flat face, prominent chin, and high forehead were distinctly modern and that this ancient person should be classified as a member of our species.

For over half a century, the fossil has been known as one of the oldest Homo sapiens skulls worldwide. In 2005, a radioactive dating study pushed back the age of the fossil skull significantly to 195,000 years ago. However, a recent study suggests that Omo I is thousands of years older.

One of the reasons volcanologist Céline 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 Omo I and her kind lived at least that long ago.

Each eruption has a unique geochemical composition, a kind of fingerprint that can be used to figure out exactly which eruption on the Ethiopian Rift would have created a layer of volcanic ash, Vidal explained. They found a match for the ash layer that covered the fossils, so they knew which eruption produced that ash and the age of that eruption.

Vidal believes the bones are at least 33,000 years older than originally believed since Oma 1 was buried beneath that ash, "All Things Considered" host Ailsa Chang said. That's because the bones could never be younger than the ground layer above them.

Geographers, not paleontologists, carried out the research endeavor. This was because it was decided to date the sediment on top of the fossils rather than try to date the fossils themselves. Omo I's exact age remains unknown, but the researchers provided a trustworthy estimation for the minimum age of the fossils.

Omo Fossils Explained

Omo is a collection of hominin bones. They were found in Omo Kibish sites close to the Omo River, which flows through Omo National Park in southwest Ethiopia between 1967 and 1974. Omo I refers to the remnants from Kamoya's Hominid Site (KHS), and Omo II refers to the remnants from Paul I. Abell's Hominid Site (PHS).

Homo sapiens are referred to as early modern humans (EMH) or anatomically modern humans (AMH) to distinguish them from extinct archaic human species. This distinction is significant for periods and areas where anatomically modern and archaic people co-existed.

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