New Twist on Ancient Human Fossils
A dusty layer of volcanic ash from a long‑gone eruption has turned researchers’ dating tools on their head. In fact, it shows that the famous early Homo sapiens fossils found in Ethiopia back in 1967 are older than anyone thought.
How the Ash Helped (and Why the Date Was Tough)
The dark ash sits on top of the soil where the bones were buried. Scientists used the ash’s geochemical fingerprints to match it with a known eruption that happened about 233,000 years ago.
- The ash arrived from the Shala volcano, about 230 miles (370 km) away.
- Its grains were too fine for conventional dating, but a detailed chemical profile gave the researchers a reliable age.
Because the fossils lie beneath this ash, they must predate the eruption – meaning they’re at least 233,000 years old, not the 200,000 years that was previously the consensus. How much older, however, is still a mystery.
Who are the Omo I Fossils?
Discovered by the legendary paleoanthropologist Richard Leakey, Omo I includes a pretty complete skull vault, a lower jaw, some vertebrae, and fragments of arms and legs. These pieces help scientists piece together early human evolution in Africa.
What’s the Big Picture for Human Origins?
Modern models of our species place the birth of Homo sapiens somewhere between 350,000 and 200,000 years ago. The Omo I fossils now fit nicely into that range, confirming that early modern humans were already thriving in a geologically volatile region.
Other historic finds, like the 300,000‑year‑old bones at Jebel Irhoud in Morocco, have raised questions because they lack certain modern traits (tall skulls, chin, etc.). Omo I, however, displays all those key features and “is the oldest Homo sapiens with unequivocal modern human traits,” as noted by study co‑author Clive Oppenheimer.
Why the Rift Valley Was a Perfect Habitat
“It’s probably no coincidence that our earliest ancestors lived in such a geologically active rift valley — it gathered rainfall into lakes, offered fresh water, attracted animals, and served as a natural migration corridor stretching thousands of kilometres,” says volcanologist Celine Vidal.
“The volcanoes gave plenty of stone for tools, and the occasional eruption forced us to sharpen our cognitive skills as the landscape changed,” she adds.
More Questions on the Horizon
The study pinned down a minimum age for the fossils, but the maximum age remains uncertain. There’s an ash layer below the fossils that hasn’t been dated yet. Pinning that down would give researchers the upper limit for the bones’ age.
So, while the ash layer gave a new “fresh coat of age” to the Omo I fossils, the story of our early ancestors continues to unfold. Stay tuned for the next piece of volcanic evidence that might just turn the timeline yet again.
