Fossils from the oldest identified Homo sapiens particular person in East Africa are extra historical than beforehand thought.
A partial H. sapiens cranium and related skeletal elements present in 1967 within the Kibish rock formation alongside Ethiopia’s Omo River date to at the least round 233,000 years in the past, pushing again the age of the fossils by 36,000 years or extra. An age effectively exceeding 200,000 years for the Ethiopian fossils, often called Omo 1, suits with current fossil discoveries suggesting that H. sapiens developed throughout Africa beginning roughly 300,000 years in the past (SN: 6/7/17).
A volcanic eruption about 233,000 years in the past left a layer of ash atop the sediment that yielded the Omo H. sapiens fossils, say volcanologist Céline Vidal of the University of Cambridge and colleagues. That ash layer displayed a chemical fingerprint matching that of a volcanic crater positioned 350 kilometers northeast of the fossil website. A large eruption there spewed volcanic ash that wafted to Omo, the researchers say. Dating of hardened ash on the volcanic crater led to the brand new age estimate for the human fossils, the scientists report January 12 in Nature.
Another Omo ash layer mendacity close to the fossil-bearing sediment, however with unsure origins, had already been dated to about 197,000 years in the past, offering the earlier age estimate (SN: 2/22/05). All sediment ages depend on measures of the decay of a radioactive type of the factor argon.
Further work will look at whether or not ash layers under Omo’s fossil-ceding sediment resulted from earlier volcanic blasts. “If successful, we might be able to bracket Omo 1 with a maximum age,” Vidal says.