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Skulls Offer First Glimpse of Early Human Faces

June 11, 2003
By JOHN NOBLE WILFORD


In the 160,000-year-old fossilized skulls of three
Ethiopians - two adults and a child - scientists think they
see for the first time the faces of the immediate ancestors
of modern humans.

Except for a few archaic characteristics, they are as
recognizable as Hamlet's poor Yorick. They are longer than
those of earlier ancestors or any contemporary Neanderthals
in Eurasia. Their midfaces are broad, but the nasal bones
are tall and narrow. The brow ridges are less prominent
than the glowering visages looking down from earlier
branches of the family tree. And the cranial vaults are
higher and within modern dimensions.

The discovery of the oldest near-modern human remains,
announced today, is considered a major step in establishing
the time and place for the emergence of anatomically modern
Homo sapiens - probably about 150,000 years ago, as genetic
studies have suggested, in Africa.

"We can now see what our direct ancestors looked like,"
said Dr. Tim D. White, a paleoanthropologist from the
University of California at Berkeley, who is a leader of
the international team that excavated and analyzed the
skulls.

That had been impossible until now because of the
frustrating gap in fossil evidence between 100,000 and
300,000 years ago, the presumed interval of transition from
prehumans to modern humans.

Dr. Christopher Stringer of the Natural History Museum in
London, who did not participate in the research, hailed the
findings as "some of the most significant discoveries in
early Homo sapiens so far."

Another independent observer, Dr. Richard G. Klein of
Stanford University, said, "These are basically modern
people, remarkably modern in appearance."

The discovery team and other scientists said in interviews
that the research appeared to confirm the idea that modern
humans originated in Africa and then spread into Asia and
Europe. In that case, they said, the enigmatic
Neanderthals, which became extinct in Europe 30,000 years
ago, could not have been direct forebears of today's
humans.

In a report in new issue of the journal Nature, released
online this morning, Dr. White and his collaborators
concluded that the Ethiopian skulls "represent the probable
immediate ancestors of anatomically modern humans" and that
"their anatomy and antiquity constitute strong evidence of
modern-human emergence in Africa."

The "out of Africa" hypothesis, forcefully advocated by Dr.
Stringer among others, had gained wide support in the two
decades since molecular research on the genetic diversity
among human populations pointed to a common ancestor in
Africa, which inevitably became known as the African Eve.
The research was based on evolutionary changes in
mitochondrial DNA, which is passed from mother to daughter.
Other studies of the male Y chromosome reached similar
conclusions.

But scientists had been unable to pin down the time of
origin or find supporting fossil evidence. The earliest
fossils of modern Homo sapiens, from Ethiopia, South Africa
and Israel, are not much more than 100,000 years old.

If correct, Dr. White's group emphasized, the new research
ruled out the alternative multiregional hypothesis, held by
a minority of scientists. They proposed that modern humans
evolved in different parts of Africa, Asia and Europe at
roughly the same time from ancient local populations. The
Homo erectus species, which had migrated out of Africa much
earlier, were thought to have evolved into Asian humans and
European humans, possibly through intermediate stages,
including Neanderthals.

Dr. Milford Wolpoff of the University of Michigan, who is a
leading proponent of the multiregional theory, questioned
whether the skulls had any bearing one way or other on the
Neanderthals' place in human evolution.

"All the specimens show is that there was a trend of
evolution in Africa toward modernity, just as there was in
China and Europe," Dr. Wolpoff said.

But Dr. White's group said the fossil skulls showed that
Homo sapiens with almost entirely human characteristics had
already evolved in Africa before Neanderthals evolved into
their classic form. Soon afterward, fully modern Homo
sapiens entered Europe, presumably from Africa by way of
the Middle East, and the Neanderthals went into their
fateful decline.

"We can conclusively say that Neanderthals had nothing to
do with modern humans," said Dr. Berhane Asfaw, a co-leader
of the discovery team from the Rift Valley Research in
Addis Ababa, the Ethiopian capital.

In a background news release to the journal articles, the
discoverers said that even if descendants of the
transitional people from Ethiopia "interbred with surviving
Neanderthal populations, the latter appear to have
contributed very little to the modern human gene pool."

The team concluded, "In this sense, we are all African."

The skull fossils were found in 1997 in an arid valley
bordering the Middle Awash River near the village of Herto,
140 miles northeast of Addis Ababa. The fossils were buried
between layers of volcanic ash, from which project
geologists determined their age to be about 160,000 years.
When the people the skulls belonged to lived there,
paleontologists said, they hunted and fished on the shore
of a shallow freshwater lake teeming with catfish,
crocodiles and hippos.

The fossils were so badly fragmented, however, that it took
years of cleaning, reassembling and analyzing before the
discoverers felt they could report their findings. They
also kept hoping they would gather more remains. They
collected more than 600 stone tools, including hand axes.
But they never uncovered the lower jaws to the skulls or
any parts of the skeletons.

Anthropologists suspect that the skulls had been
deliberately removed from the bodies as part of some
ancient mortuary practice. Close inspection revealed
parallel incisions around the perimeter of one skull, more
cut marks on the other two. Similar modifications have been
observed by anthropologists in societies, including some in
New Guinea, in which the skulls of ancestors are preserved
and worshiped.

The three skulls, all missing the lower jaws, were
excavated a few hundred feet from one another. The most
complete one, probably that of an adult male, especially
impressed scientists with its humanlike size and shape,
very nearly modern.

So the discoverers decided the specimen belonged in the
same genus and species as modern humans, Homo sapiens. But
there were just enough differences, the scientists
concluded, that the fossils were probably a subspecies,
Homo sapiens idàltu, to differentiate them from fully
modern humans, Homo sapiens sapiens. Idàltu is a word
meaning "elder" in the local Afar language.

"When we compared the cranium to thousands of modern human
crania, several dimensions and characters were outside the
modern range," Dr. White said in an interview. "If we just
called it homo sapiens sapiens, that implied it's the same
thing, and it's actually not the same, though very close."

In a commentary accompanying the journal reports, Dr.
Stringer said this fossil "helps to clarify the pattern of
early Homo sapiens evolution in Africa, as it shows an
interesting combination of features from archai, early
modern and recent humans."

The second skull was of an even larger adult with modern
human characteristics. The third was the skull of a child
who died at the age of about 6 or 7 years. All the
specimens are being studied at the National Museum of
Ethiopia in Addis Ababa.

"The key point is that we now have good fossil evidence of
people like us evolving in Africa when the only people in
Europe were Neanderthals," said Dr. Klein of Stanford. "The
Herto humans are anything but Neanderthals."

http://www.nytimes.com/2003/06/11/sc...c70ca1a69df2ec