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."
If the bones are about as old as the Homo group, that would argue that naledi is "a snapshot of … the evolutionary experimentation that was going on right around the origin" of Homo, he said. If they are significantly younger, it either shows the naledi retained the primitive body characteristics much longer than any other known creature, or that it re-evolved them, he said.
Eric Delson of Lehman College in New York, who also wasn't 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.
"This stuff is like a Sherlock Holmes mystery," declared Bernard Wood of George Washington University in Washington, D.C., who was not involved in the study. Visitors to the cave must have created artificial light, as with a torch, Wood said. The people who did cave drawings in Europe had such technology, but nobody has suspected that mental ability in creatures with such a small brain as naledi, he said.
The fact the fossils were found in a chamber has led paleoanthropologists to believe that the ancient species also appeared to bury its dead, a trait previously believed to be uniquely human, through a process of deduction.
Potts said a deliberate disposal of dead bodies is a feasible explanation, but he added it's not clear who did the disposing. Maybe it was some human relative other than naledi, he said.
Virtually no other remains from other species were found in the cave and the bones bore no claw or tooth marks – suggesting they were not the leftovers from a predator's larder or death trap.
While explaining to Reuters more about Homo naledi, Berger said the species really was like nothing we had ever seen before.
"A tiny little head the size of an orange with very human like size teeth, but also teeth that are shaped like more primitive hominin. The body is unusual, ape like in the shoulders, primitive in the pelvis but the upper limbs and lower limbs are largely human-like, well that is except for the very curved distal phalanges of the fingers which indicate…which create a very odd package, a mosaic hominid, that was clearly a long distance walker but also something that was the very roots of our genus," he said.
He set aside another theory that they may have been hiding their dead deep underground, simply to keep off scavengers like the long-legged hyena.
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 in an email.
At the news conference in South Africa, Berger disputed that.
"Could this be the body of homo erectus? Absolutely not. It could not be erectus," Berger said.
This is not the first time that the study of our relatives, extinct or living, has yielded evidence that humans do not have the monopoly on certain kinds of behavior.
Jane Goodall in 1960 famously observed chimpanzees, our closest living relative, using grass stems for termite "fishing", the first recorded use of a crude tool by non-humans.
Homo naledi, discovered in the cave in September 2013, had a brain slightly larger than a chimpanzee's, but its age remains an enigma.
"We can see from their physical morphology, their appearance, at least where their species originates in time. It must go to the base of our genus, the root of our genus, and if so, and if our present understanding is correct, then that must be in excess of 2.5 million years that is the species originates" said Berger.
There were also no fossils with them from other animals that could provide clues.
The surrounding area is a U.N. World Heritage site, named the "Cradle of Humankind" by the South African government because of its rich collection of hominid fossils.
CCTV America - Agencies
