Long-lost relative
Discovery of new human ancestor raises many questions,
MAGALIESBURG, SOUTH AFRICA— Scientists say they’ve discovered a new member of the human family tree, revealed by a huge trove of bones in a barely accessible, pitch-dark chamber of a cave in South Africa.
The creature shows a surprising mix of humanoid and more primitive characteristics — some experts called it “bizarre” and “weird.”
And the discovery presents some key mysteries: How old are the bones? And how did they get into that chamber, reachable only by a complicated pathway that includes squeezing through passages as narrow as about 18 centimetres?
The site, about 50 kilometres northwest of Johannesburg, has yielded some 1,550 specimens since its discovery in 2013. The fossils represent at least 15 individuals.
Researchers named the creature Homo naledi. That reflects the “Homo” evolutionary group, which includes modern people and our closest extinct relatives, and the word for “star” in a local language. The find was made in the Rising Star cave system.
The creature, which evidently walked upright, represents a mix of traits. For example, the hands and feet look like Homo, but the shoulders and the small brain recall Homo’s more ape-like ancestors, the researchers said.
Lee Berger, a professor at the University of the Witwatersrand in Johannesburg who led the work, said naledi’s anatomy suggest it arose at or near the root of the Homo group, which would make the species between 2.5 million and 2.8 million years old. The discovered bones themselves may be younger, he said.
The researchers announced the discovery Thursday in the journal eLife and at a news conference in the Cradle of Humankind, a site near the Magaliesburg. They said they were unable to determine an age for the fossils because of unusual characteristics of the site, but are still trying.
Berger said researchers are not claiming that naledi was a direct ancestor of modern-day people, and experts unconnected to the project said they believed it was not.
Rick Potts, director of the human origins program at the Smithsonian Institution’s Natural History Museum, who was not involved in the discovery, said that without an age, “there’s no way we can judge the evolutionary significance of this find.”
Not everybody agreed that the discovery revealed a new species. Tim White of the University of California, Berkeley, called that claim questionable. “From what is presented here, (the fossils) belong to a primitive Homo erectus, a species named in the 1800s,” he said.