MAGALIESBURG // 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 human-like and more primitive characteristics – some experts called it “bizarre” and “weird”.
The discovery also presented 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 17.8 centimetres?
The fossils – which represent at least 15 individuals – were found by a spelunker, 48 kilometres northwest of Johannesburg. The site has yielded some 1,550 specimens since its discovery in 2013.
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.
Lee Berger, a professor at the University of the Witwatersrand in Johannesburg who led the work, said naledi’s anatomy suggest that it arose at or near the root of the Homo group, which would make the species some 2.5 million to 2.8 million years old. The discovered bones themselves may be younger, said Mr Berger.
At a news conference on Thursday in the Cradle of Humankind, a site near the town of Magaliesburg where the discovery was made, bones were arranged in the shape of skeleton in a glass-covered wooden case. Fragments of small skulls, an almost complete jawbone with teeth, and pieces of limbs, fingers and other bones were arrayed around the partial skeleton.
The researchers, who announced the discovery in the journal eLife, said they could not determine an age for the fossils because of unusual characteristics of the site.
Mr Berger said researchers are not claiming that neledi 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”.
Eric Delson of Lehman College in New York, who also was not involved with the work, said his guess is that naledi fits within a known group of early Homo creatures from around 2 million year ago.
Besides the age of the bones, another mystery is how they got into the difficult-to-reach area of the cave. The researchers said they suspect the naledi may have repeatedly deposited their dead in the room, but alternatively it may have been a death trap for individuals that found their own way in.
* Associated Press
