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“Caveful of Clues About Early
Humans”
Interbreeding With Neanderthals Among Theories Being Explored
- September 20, 2004; Page A06
See text of paper below.
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Caveful of Clues About Early Humans
By Fredric Heeren
Special to The Washington Post
“Field research” projects
often require scientists to endure discomfort and danger to get
where they need to be, but not many can trump this
summer’s expedition to what may be the world’s most
inaccessible human fossil site, a cave in the foothills of
Romania’s Carpathian Mountains.
For the seven-member team, the hazards of
reaching the site, accessible only by diving through frigid
underwater passages, were worth it. Their finds may help answer
some of the most hotly debated questions about early humans:
Did they make love or war with Neanderthals? Were Neanderthals
intellectually inferior to our human ancestors?
This may be asking a lot of the scanty
fossil remains of three individuals who lived 35,000 years ago,
but their age makes them the earliest modern humans ever found
in Europe. The uniqueness of the site, which was discovered in
2002, was motivation enough for the specially trained team to
devote a month of cold and dangerous underground journeys to
reach and excavate the site known as Pestera cu Oase -- Cave
with Bones.
The team included a Portuguese shipwreck
diver and archaeologist, a French Neanderthal specialist, a
Romanian cave biologist, and the three Romanian adventurers who
discovered the human fossils while exploring submerged caves.
At the start of each day’s nine-hour
excursion underground, team members stepped into a frigid
mountain river that flows into a cave, their helmet-mounted
lights piercing the perpetual fog of the cave’s 100
percent humidity. As the equipment-laden crew sloshed past
stalagmites, the cave narrowed and the air temperature plunged
from the 90s to the upper 40s Fahrenheit.
Further in, the ceiling lowered until they
were forced, first, to swim on their backs and, finally, don
their diving masks and enter a narrow, 80-foot-long underwater
passage called “the sump.” Underwater visibility
was about three feet.
Lead diver Stefan Milota warned newcomers:
“Do you know how long it takes to die in the sump?
Twenty, thirty seconds and you’re gone.”
When Milota first told biologist Oana
Moldovan in 2002 that he had found a human jaw in a closed-off
chamber, Moldovan wanted to see for herself -- even though she
had to learn to dive to do it.
“I had to see the cave,” said
Moldovan, now the team’s project coordinator. “So I
was very motivated. But I was very scared. My first time, it
was horrible.”
Surfacing inside another chamber, the
divers peeled off their wetsuits and changed into warm
clothing. The next step was climbing “the pit,” a
series of underground cliff faces that the cavers scaled in
dizzying climbs up a succession of ladders they had carried in
earlier.
Finally, to reach the gallery of bones,
they passed through “the gate,” an opening that
Milota had first spotted when he felt warmer air emerging. He
and his explorer friends widened it just enough for the
thinnest of them to squeeze through. Each day, the cavers had
to plunge head-and-arms first at a slight uphill angle, then
wriggle and rest, wriggle and rest, to cover the final, winding
10 feet.
Inside the final gallery, there was room
for only three workers at a time because the rest of the floor
was covered with thousands of fragile fossils. Most belonged to
a cave bear species that became extinct 10,000 years ago --
animals almost twice as big as today’s bears.
The original entrance caved in long ago,
sealing off the galleries from the outside. After two labs
independently yielded radiocarbon dates of about 35,000 years
for the jaw, or mandible, that Milota had found, more
scientists took interest. In a 2003 expedition, they found a
full face and an ear region of a skull from two more
individuals, with puzzling traits that suggested a mix of
Neanderthal and human features, something scientists had
thought impossible.
Anthropologist Erik Trinkaus of Washington
University in St. Louis and Joao Zilhao of Cidade University in
Lisbon joined this summer’s excavation to look for more
specimens and to try to find out how the human remains got into
the cave. Because they turned up no sign of torches, charcoal
or tools, they concluded that the human remains had washed in
through fissures.
The biggest payoff of the summer was the
discovery of more fragments of the three individuals found
earlier, which added to the evidence of hybrid traits.
Trinkaus said the Oase fossils show
features of modern humans: projecting chin, no brow ridge, a
high and rounded brain case. But they also have clear archaic
features that place them outside the range of variation for
modern humans: a huge face, a large crest of bone behind the
ear and enormous teeth that get even larger toward the back.
Trinkaus made a CT scan of the face to
measure the unerupted teeth. “To find wisdom teeth that
big,” he said, “you have to go back 500,000
years.”
The team considered whether early humans
might have interbred with other hominids with Neanderthal-like
features, but “in this time period,” said Trinkaus,
“the only archaic humans those modern humans could have
interbred with were Neanderthals.” The mosaic of
Neanderthal and modern traits remind Trinkaus and Zilhao of
similar traits they found in a 25,000-year-old fossil of a
child in Portugal.
Researchers pondering why the Neanderthals
died out have speculated that early humans might have killed
them off, and Zilhao said the signs of interbreeding do not
exclude that possibility. “We know that even when people
fight, the winner might kill the males and keep the females
from the other side,” he said.
The signs of interbreeding challenge the
standard wisdom that Neanderthals were a distinct, less
intelligent species.
“If you look at the archaeological
evidence,” argued Trinkaus, “which includes things
like burials, there is very little difference between what we
find associated with Neanderthals and what we find associated
with early modern humans -- from the same time period.”
Richard Klein of Stanford University
thinks this holds true only until about 50,000 years ago, when
modern human behavior changed dramatically. “There could
have been interbreeding,” Klein conceded. “But all
the genetic evidence we have suggests that, if it occurred, it
was remarkably rare.”
Six years ago, Zilhao and Francesco
d’Errico of the University of Bordeaux published evidence
that Neanderthals independently invented and used personal
ornamentation. Zilhao said these finds have changed the view
that Neanderthals were an inferior species.
Klein said the picture is changing, but
not in that direction. The real question today, he said, is
“whether modern humans fully replaced the Neanderthals or
simply swamped them” genetically, with greater numbers.
“And it may never be possible to say.”
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