By: Lynsey Chutel Malcolm Ritter The
Associated Press,
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 cave in South Africa.
The creature shows a surprising mix of human-like 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
17.8 centimetres?
The site, about 30 miles 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
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, 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 village of Magaliesburg. They said they were unable to determine an age for
the fossils because of unusual characteristics of the site, but that they are
still trying
.
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.”
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.
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.
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.
Malcolm Ritter reported from New York.
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