Acting on a tip from spelunkers two years ago, scientists in South Africa discovered what the cavers had only dimly glimpsed through a crack in a limestone wall deep in the Rising Star cave: lots and lots of old bones.
The remains covered the earthen floor beyond the narrow opening. This was, the scientists concluded, a large, dark chamber for the dead of a previously unidentified species of the early human lineage — Homo naledi.
The new hominin species was announced on Thursday by an international team of more than 60 scientists led by Lee R. Berger, an American paleoanthropologist who is a professor of human evolution studies at the University of the Witwatersrand in Johannesburg. The species name, H. naledi, refers to the cave where the bones lay undisturbed for so long; “naledi” means “star” in the local Sesotho language.
In two papers published this week in the open-access journal eLife, the researchers said that the more than 1,550 fossil elements documenting the discovery constituted the largest sample for any hominin species in a single African site, and one of the largest anywhere in the world. Further, the scientists said, that sample is probably a small fraction of the fossils yet to be recovered from the chamber. So far the team has recovered parts of at least 15 individuals.
“With almost every bone in the body represented multiple times, Homo naledi is already practically the best-known fossil member of our lineage,” Dr. Berger said.
Besides introducing a new member of the prehuman family, the discovery suggests that some early hominins intentionally deposited bodies of their dead in a remote and largely inaccessible cave chamber, a behavior previously considered limited to modern humans. Some of the scientists referred to the practice as a ritualized treatment of their dead, but by “ritual” they said they meant a deliberate and repeated practice, not necessarily a kind of religious rite.
“It’s very, very fascinating,” said Ian Tattersall, an authority on human evolution at the American Museum of Natural History in New York, who was not involved in the research. “No question there’s at least one new species here,” he added, “but there may be debate over the Homo designation, though the species is quite different from anything else we have seen.”
A colleague of Dr. Tattersall’s at the museum, Eric Delson, who also is a professor at Lehman College of the City University of New York, was also impressed, saying, “Berger does it again!”
Dr. Delson was referring to Dr. Berger’s previous headline discovery, published in 2010, also involving cave deposits at the Cradle of Humankind site, 30 miles northwest of Johannesburg. He found many fewer fossils that time, but enough to conclude he was looking at a new species, which he named Australopithecus sediba. Geologists said the individuals lived 1.78 million to 1.95 million years ago, when australopithecines and early species of Homo were contemporaries.