Paleoanthropologists have uncovered two new specimens of Homo erectus at the East Turkana site in Kenya. They’ve also verified the age of a skull fragment of Homo erectus — one of the oldest specimens attributable to this species — found earlier at the same site.
This is an artist’s reconstruction of Homo erectus. Image credit: Yale University.
“Homo erectus is the first hominin that we know about that has a body plan more like our own and seemed to be on its way to being more human-like,” said Dr. Ashley Hammond, a researcher at the American Museum of Natural History.
“It had longer lower limbs than upper limbs, a torso shaped more like ours, a larger cranial capacity than earlier hominins, and is associated with a tool industry — it’s a faster, smarter hominin than Australopithecus and earliest Homo.”
In 1974, scientists at the East Turkana site in Kenya found one of the oldest specimens of Homo erectus: a 1.9-million-year-old skull fragment. The specimen is only surpassed in age by a 2-million-year-old skull specimen in South Africa.
But there was pushback within the field, with some paleoanthropologists arguing that the East Turkana specimen could have come from a younger fossil deposit and was possibly moved by water or wind to the spot where it was found.
To pinpoint the locality, Dr. Hammond and colleagues relied on archival materials and geological surveys.
‘We had to go through hundreds of pages from old reports and published research, reassessing the initial evidence and searching for new clues,” said Dr. Dan Palcu, a geoscientist at the University of São Paulo and Utrecht University.
“We also had to use satellite data and aerial imagery to find out where the fossils were discovered, recreate the scene, and place it in a larger context to find the right clues for determining the age of the fossils.”
Although located in a different East Turkana collection area than initially reported, the skull specimen was found in a location that had no evidence of a younger fossil outcrop that may have washed there. This supports the original age given to the fossil.
A partial pelvis of Homo erectus found at the East Turkana site in Kenya. Image credit: A. Hammond / American Museum of Natural History.
Within 50 m of the reconstructed location, the researchers found two new specimens: a partial pelvis and a foot bone.
“Although they could be from the same individual, there’s no way to prove that after the fossils have been separated for so long,” they said.
“But they might be the earliest postcrania specimens yet discovered for Homo erectus.”
“Our work also suggests that this early Homo erectus was found in a paleoenvironment that included primarily grazers that prefer open environments to forest areas and was near a stable body of water, as documented by freshwater sponges preserved in the rocks.”
The findings were published in the journal Nature Communications.
A.S. Hammond et al. 2021. New hominin remains and revised context from the earliest Homo erectus locality in East Turkana, Kenya. Nat Commun 12, 1939; doi: 10.1038/s41467-021-22208-x