The New York Times
April 8, 2001

On the Trail of a Few More Ancestors
By JOHN NOBLE WILFORD

Fossils of what may be the earliest known ancestor of the human family have
been unearthed in Kenya. The bones and teeth are about 6 million years old,
at least 1.5 million years earlier than any similar finds, and so their
discovery could be a major advance shaking up the human family tree yet again.
They are already shaking up the family of paleontologists.

As details emerged in recent weeks, the age of the fossils was the only
aspect that seemed beyond dispute. To assertions by the discoverers that
the individual mostly walked upright and was a direct ancestor of modern
humans, many prominent scientists have reacted with head- shaking
skepticism bordering on disbelief.

These critics think the fossils are more likely to be of a chimpanzee or
one of its ancestors. This in itself would be a significant find because
the early fossil record of chimpanzees, the nearest relatives to humans, is
barren.

But some researchers suspect the growing controversy may be fueled in part
by personal animosities and territorial disputes. One of the discoverers,
Dr. Martin Pickford of the College de France, has made important enemies in
his profession, notably Richard Leakey of the Kenyan fossil-hunting family.
Others among Dr. Pickford's critics suggested the newly found fossils might
have been collected illegally on the turf of another paleontologist.
On Friday, Dr. Pickford and Dr. Brigitte Senut, an anatomist at the
National Museum of Natural History in Paris, denied the charge of digging
without a permit and said that most of the scientific criticism was coming
from paleontologists who had not seen the original fossils or even casts of
them.

"The newly discovered material probably troubles the established scenario
about human evolution and especially evolution of bipedalism," Dr. Senut
said in an e-mail message from Paris. "Our findings have been unfairly
judged by a few colleagues."

If the discoverers are correct, the fossils represent a hominid of an
entirely new genus and species, which has been named Orrorin tugenensis.
Orrorin means "original man" in the local dialect. At an age of 6 million
years, it could be one of the first hominids living after their split from
other lineages leading to apes.

In a journal of the French Academy of Sciences, Dr. Senut and Dr. Pickford,
a paleontologist, reported that partial remains of thigh bones bore signs
suggesting that the creature "was already adapted to habitual or perhaps
even obligate bipedalism when on the ground, but that it was also a good
climber."

Bipedality, walking upright on two legs, is considered a defining
characteristic of hominids, so whether Orrorin could do so is the point of
sharpest dispute among scientists. Their conclusion that it could, as well
as the fact that its teeth were smaller than those of apes and many other
subsequent hominids, persuaded Dr. Senut and Dr. Pickford that Orrorin
stood on a direct line leading to modern humans, bypassing intermediate
groups such as Australopithecus afarensis, best known by the 3.2
million-year-old Lucy skeleton found in Ethiopia in 1974.

The story of early human origins has already been thrown into confusion by
a discovery announced last month by Dr. Meave G. Leakey, a paleontologist
and the wife of Richard E. Leakey. She reported finding in Kenya the
3.5-million-year-old skull and other fossils of another new genus and
species, Kenyanthropus platyops. The skull also appeared to push Lucy off
to a side branch of the family tree, Dr. Leakey said. Her interpretation
was generally greeted with peer approval, unlike the Senut- Pickford find.
In a carefully worded response, Dr. Leslie C. Aiello and Dr. Mark Collard,
paleontologists of University College London, wrote in the journal Nature
that the sediments where the Orrorin fossils were excavated, in the Tungen
Hills northwest of Nairobi, had been thoroughly studied before and were
established to have been laid down about six million years ago.
The oldest previously recognized member of the hominid lineage is
Ardipithecus ramidus, based on 4.5- million-year-old specimens collected in
Ethiopia. It is not yet clear whether this species walked upright. Dr.
Senut and Dr. Pickford contend that Ardipithecus was more likely an
ancestor of African apes than of humans. They also cast most
australopithecines out of the human ancestral line.

Of the 12 fossils in the new collection, fragments of the upper parts of
femurs, or thigh bones, have received the closest attention. The
discoverers maintain that the head of the bone is large and humanlike in
relation to the size of the neck of the bone. This and other
characteristics, they argue, supports the conclusion that this species was
bipedal.

But Dr. Alan Walker, an anatomist at Pennsylvania State University who has
often excavated with the Leakeys, said he was "not impressed with their
evidence" for bipedality of the species. Evidence from the lower end of the
femur would have been more convincing, he said, but that was missing, and
other cited evidence could have contradictory interpretations.

"If Orrorin was not bipedal then neither was Lucy, and we have to go back
to the drawing board," Dr. Pickford responded. "In many ways, the Orrorin
femur is closer to those of modern humans than they are to Lucy's, and they
are quite different from those of chimps."

Dr. Daniel E. Lieberman, a George Washington University paleontologist,
said: "I swear the fossils are so chimpanzeelike that it's incredible. If
it were a chimpanzee, it would be the first record we have of their early
evolution."

Although he said the discoverers were competent researchers, Dr. Milford
Wolpoff of the University of Michigan complained of the "low density of
information, not enough to be claiming all this."

Dr. Andrew Hill, a Yale paleontologist, said he had conducted excavations
near the discovery site for more than two decades and still had a
legitimate permit that covered the land where the Orrorin fossils were
found. He said Dr. Pickford had encroached on his territory by sidestepping
usual channels to obtain a permit to work the same land.

Dr. Pickford said he had a research permit that was issued in 1998 by the
office of President Daniel arap Moi of Kenya, and it was valid through Dec.
31, 2001. The fossils in question were collected last year. His sponsorig
institution was the Community Museums of Kenya, which he had helped found
Previously, all permits were granted through the National Museums of Kenya,
where Dr. Meave Leakey is the principal paleontologist and her husband was
director for a long time.

Several scientists suggested that personal animosities might be behind much
of the controversy. Dr. Pickford and Mr. Leakey once worked together, but
had a falling- out that became public in 1985 when Dr. Pickford was barred
from the national museum. Eventually, Dr. Pickford co-wrote a book,
"Richard E. Leakey: Master of Deceit."

In March last year, Dr. Pickford was arrested on charges of collecting
fossils without a permit and spent five days in a Kenyan jail. Now he has
sued Mr. Leakey, among others, alleging unlawful arrest and malicious
harassment.

The debate would probably be equally intense on a scientific level
because, paleontologists said, so much such as claims of finding the earliest
known human ancestor  is being made of a modest, though fascinating,
collection of fossils. Everyone seemed to expect the dispute to last for
months, even years.

Oryginal:
http://www.nytimes.com/2001/04/08/science/08FOSS.html

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