Rising Star Cave,
South Africa (CNN)When an amateur caver and university geologist arrived at Lee
Berger's house one night in late 2013 with a fragment of a fossil jawbone in
hand, they broke out the beers and called National Geographic.
Berger, a professor
at the University of the Witwatersrand in Johannesburg, South Africa, had
unearthed some major finds before. But he knew he had something big on his
hands.
What he didn't know
at the time is that it would shake up our understanding of the progress of
human evolution and even pose new questions about our identity.
Two years after they
were tipped off by cavers plumbing the depths of the limestone tunnels in the
Rising Star Cave outside Johannesburg, Berger and his team have discovered what
they say is a new addition to our family tree.
The team is calling
this new species of human relative "Homo naledi," and they say it
appears to have buried its dead -- a behavior scientists previously thought was
limited to humans.
Berger's team came
up with the startling theory just days after reaching the place where the
fossils -- consisting of infants, children, adults and elderly individuals --
were found, in a previously isolated chamber within the cave.
The team believes
that the chamber, located 30 meters underground in the Cradle of Humanity world
heritage site, was a burial ground -- and that Homo naledi could have used fire
to light the way.
Homo naledi's skull
protected a brain about the size of an average orange, researchers say.
Homo naledi's teeth
are similar to those of the earliest-known members of our genus, scientists
say.
The six women were
able to fit through a 7-inch opening in the cave to reach the chamber where the
bones were found.
"We have just
encountered another species that perhaps thought about its own mortality, and
went to great risk and effort to dispose of its dead in a deep, remote, chamber
right behind us," Professor Lee Berger, the director of the project, told
CNN.
Scientists say
they've discovered a new species of human relative in the Rising Star cave in
the Cradle of Humankind world heritage site outside Johannesburg
A composite skeleton
of Homo naledi is surrounded by some of the hundreds of other fossil elements
recovered from the Dinaledi Chamber of the cave.
"Overall, Homo
naledi looks like one of the most primitive members of our genus, but it also
has some surprisingly human-like features, enough to warrant placing it in the
genus Homo," said John Hawks of the University of Wisconsin-Madison.
Homo naledi's feet
are almost identical to ours -- indicating that it was well-suited to long
distance walking.
Homo naledi's hands
suggest tool-making and climbing capabilities.
The braincase of a
composite male skull of Homo naledi measures just 560 cubic centimeters in
volume — less than half that of the modern human skull pictured behind it.
Homo naledi's skull
protected a brain about the size of an average orange, researchers say.
Homo naledi's teeth
are similar to those of the earliest-known members of our genus, scientists
say.
"There is no
damage from predators, there is no sign of a catastrophe. We had to come to the
inevitable conclusion that Homo naledi, a non-human species of hominid, was
deliberately disposing of its dead in that dark chamber. Why, we don't know,"
Berger told CNN.
"Until the
moment of discovery of 'naledi,' I would have probably said to you that it was
our defining character. The idea of burial of the dead or ritualized body
disposal is something utterly uniquely human."
Standing at the
entrance to the cave this week, Berger said: "We have just encountered
another species that perhaps thought about its own mortality, and went to great
risk and effort to dispose of its dead in a deep, remote, chamber right behind
us."
"It absolutely
questions what makes us human. And I don't think we know anymore what
does."
The first undisputed
human burial dates to some 100,000 years ago, but because Berger's team hasn't
yet been able to date naledi's fossils, they aren't clear how significant their
theory is.
Berger tried to put
the new find into perspective.
"This is like
opening up Tutankhamen's tomb," he said. "It is that extreme and
perhaps that influential in this stage of our history."
Almost human but not
quite
Homo naledi is a
strange mosaic of the ancient and the thoroughly modern.
Naledi's brain was
no bigger than an orange, scientists say. Its hands are superficially
human-like, but the finger bones are locked into a curve -- a trait that
suggests climbing and tool-using capabilities.
Homo naledi was
relatively big: it stood about 5 feet tall, had long legs, and its feet are
almost identical to ours, suggesting it had the ability to walk long distances.
The braincase of a
male Homo naledi is less than half the size of the modern human skull.
"Overall, Homo
naledi looks like one of the most primitive members of our genus, but it also
has some surprisingly human-like features, enough to warrant placing it in the
genus Homo," says John Hawks of the University of Wisconsin-Madison, a senior
author on the papers describing the new species that were published Thursday.
The scientists can
make these claims, in part, because of the sheer scale of the find.
In the vault at the
University of Witwatersrand, hundreds of priceless specimens lie in padded
cases across the room.
So far they've
unearthed more than 1,500 fossil remains in total -- the largest single hominin
find yet revealed on the continent of Africa, the cradle of human evolution.
Gathering the
fossils was dangerous work.
Berger, a National
Geographic Explorer-in-Residence, was already well-known for his discovery of
"Australopithecus sediba," another species of human ancestor, in
2008. But this expedition would face unique challenges.
The fossils were
found at the end of a series of chambers and tight squeezes deep underground,
some 90 meters (100 yards) from the cave entrance. To get there, scientists
would have to squeeze through a 7-inch wide cave opening.
So Berger put out a
call on social media for skinny scientists and cavers who could fit through the
tiny chute and bring up the bones.
Within days Berger
had dozens of responses, and he eventually selected a team of six
"underground astronauts" -- all women -- to do the job.
Berger himself could
not reach the chamber where the remains lay, but he followed all of the
exploration on real-time monitors above ground and communicated with his team.
"It is the
heart of exploration. What we are privileged enough to do is going into the
next new unexplored spaces," says Berger.
A field of bones
In the first few
days of the expedition, the biggest problem was knowing where to step.
"The first
thing that you would see, especially in the early stages of the investigation,
was just bones. Bone debris everywhere," says K. Lindsay Hunter, an
American scientist and one of the "astronauts" on the Rising Star
expeditions, which were conducted in November 2013 and March 2014.
Marina Elliott,
another of Berger's astronauts, described the scene underground as "some
of the most difficult and dangerous conditions ever encountered in the search
for human origins."
"We found
everything from infants to babies to toddlers to teens, young adults, old
individuals. It is like nothing that we could have ever imagined," says
Berger. "Homo naledi is already practically the best-known fossil member
of our lineage."
The team claims to
have uncovered remains of at some 15 distinct individuals, but say this is only
the beginning.
"The chamber
has not given up all its secrets," Berger says. "There are
potentially hundreds if not thousands of remains of Homo naledi still down
there."
Berger says their
discovery raises haunting questions about our deep past, and about our very
identity. Many mysteries remain, and other scientists may well challenge some
of the team's controversial conclusions. But few will dispute that Homo naledi
is truly significant.
Years of careful
exploration lie ahead. "This was right under our nose," says Berger.
"And we didn't see it. What else is out there?"
No comments:
Post a Comment