Researchers said that they used the fingerprints of geochemistry to study a thick layer of ash that was found on deposits with fossils, to confirm that it was caused by the eruption of a volcano that caused the release of lava and ash over a large area of Ethiopia about 233,000 years ago.
The researchers pointed out that the presence of fossils under this ash means that the presence of fossils preceded the eruption of the volcano, but it was not clear how long it lasted in years. Previously, the fossils were believed to be approximately 200,000 years old.
The fossils, called Omo 1, were discovered in southwestern Ethiopia in an area called the Omo-Kepesh Geological Formation during an expedition led by anthropologist Richard Leakey. The fossils include a nearly complete skull and mandible, some phalanges of the spine, and parts of the arms and legs.
Scientists are seeking to reveal more about the timing of the origin of the human race in Africa.
The new findings are consistent with the latest scientific models that place the emergence of Homo sapiens sometime between 350,000 and 200,000 years ago, says Céline Vidal, a volcanologist at the University of Cambridge and lead author of the study published in the journal Nature.
Research published in 2017 showed that the bones and teeth discovered at the Jebel Irhoud site in Morocco are more than 300,000 years old, and represent the oldest fossils attributed to Homo sapiens.
But some scientists are raising doubts about whether the Jebel Irhud fossils really belong to our species.