[Paleopsych] NYT: For Neanderthals and Homo Sapiens, Was It De-Lovely?
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Fri Apr 15 13:53:43 UTC 2005
For Neanderthals and Homo Sapiens, Was It De-Lovely?
February 15, 2005
By JOHN NOBLE WILFORD
The scientists did not get around to the nitty-gritty question until
the fourth hour of a two-and-a-half-day symposium on Neanderthals,
held recently at New York University.
A strong consensus was emerging, they agreed, that the now-extinct
Neanderthals were a distinct evolutionary entity from modern humans,
presumably a different species. They were archaic members of the human
family, robust with heavy brow ridges and forward-projecting faces,
who lived in Europe and western Asia from at least 250,000 years ago
until they vanished from the fossil record about 28,000 years ago.
Neanderthals may have seen their first modern Homo sapiens some
100,000 years ago in what is now Israel. The two people almost
certainly came in contact in Europe in the last centuries before the
dwindling Neanderthal population was replaced forever by the intruding
Taking his turn at the symposium lectern, Dr. James C. M. Ahern, a
paleoanthropologist at the University of Wyoming, acknowledged:
"Neanderthals are different. The degree of difference is relatively
vast, but that is not the most interesting question out there."
The question was, he continued, "Did Neanderthals and modern humans do
There it was, out in the open again, the question that has persisted
since the first fossils of these people were discovered in the Neander
Valley of Germany in 1856. Could the two people with a shared distant
ancestry and family resemblance have interbred? Is there any evidence
that Europeans today carry some Neanderthal genes?
For the international gathering of scientists, the issue exposed the
uncertainty over the definition of species. Its conventional meaning
is a group of interbreeding creatures that are reproductively isolated
from others. Hybridization of species is rare in mammals. One common
example is the mating of an ass and a mare, producing the sterile
The conferees debated, but never resolved, the possibility that
Neanderthals could have been an evolutionary and anatomical species,
distinct from Homo sapiens, but not strictly an isolated biological
species. That is, the two species may have been enough alike to mate
and produce fertile offspring.
Again, Dr. Ahern encapsulated the issue, "How much difference is too
much" for viable interbreeding to occur?
Dr. Chris Stringer, a paleontologist at the Natural History Museum in
London, noted that some species apparently less close than
Neanderthals and modern humans can interbreed and produce hybrids. Dr.
Stringer is a leading proponent of the theory that modern Homo sapiens
emerged in Africa as early as 150,000 years ago and then spread to
Asia and Europe, replacing the remnants of archaic humans they
Dr. Erik Trinkaus, a Neanderthal expert at Washington University in
St. Louis, who was not at the meeting, contends that the
24,500-year-old skeleton of a young boy found in Portugal appeared to
be a Neanderthal-Homo sapiens hybrid. The interpretation has so far
been viewed with skepticism.
Dr. Mark Stoneking of the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany, said that he and colleagues had
looked for answers in the patterns of genetic variation in
contemporary human populations and the analysis of ancient DNA from
fossils of Neanderthals and early modern humans. Neither approach, he
said, provided any indication of interbreeding between the two
"That does not rule out some genetic contribution" from Neanderthals
to Europeans' ancestry, Dr. Stoneking said.
Dr. David Serre of McGill University in Montreal described the
analysis of the maternally inherited mitochondrial DNA found in 24
Neanderthals and 40 early modern human remains. The results seemed to
exclude any significant contribution of Neanderthal genes to Homo
sapiens, perhaps less than 1 percent. Therefore, he concluded, they
were "two distinct biological species."
Dr. Katerina Harvati, also of the Planck Institute in Leipzig,
recently conducted research applying a "quantitative method" to
determine the degree of anatomical difference that justifies
classifying specimens as different species. She and colleagues
examined the variation of specific parts of the craniums and faces of
modern humans and Neanderthals as well as 12 existing species of
nonhuman primates. The two living species of chimpanzees, for example,
appeared to be more closely related to each other than Neanderthals
are to humans.
Dr. Harvati and Dr. Terry Harrison, a paleontologist at N.Y.U.,
organized the symposium, "Neanderthals Revisited: New Approaches and
More than species differences may have kept Neanderthals and humans
sexually apart, if indeed that was the case. Their opportunities may
have been limited.
Dr. Ahern said in an interview that it was "surprising how little
overlap there was" between the two species in Europe." It had been
thought that modern humans from Africa began arriving in Europe about
40,000 years ago and so could have competed with and mingled with the
local population for at least 12,000 years. But the dating of fossil
and archaeological evidence is now being revised, leaving much less
time when the two species could have had close contact.
"It's a real scientific problem," said Dr. Randall White, an
archaeologist specializing in European ice age culture at N.Y.U. "How
to interpret the overlap of Neanderthals and modern humans, their
interactions and cultural exchanges, the causes of Neanderthal
extinction, all depends on what are the real dates of their possible
Some of the most solid evidence for overlap, the researchers said,
does not appear until toward the end of the Neanderthals' known
existence, when their populations were probably sparse.
Dr. Stringer said some explanations for Neanderthal extinction were
being re-examined. Perhaps the technological superiority of modern
humans was "not as clear-cut as some of us thought," he said. Perhaps
Neanderthals, though adapted to a cold climate, could not survive the
rapid and repeated changes of cold and warm periods of that time.
"It was not bad genes but bad luck for the Neanderthals," Dr. Stringer
said. "Modern humans may have had no direct effect on Neanderthal
extinction. They actually walked into empty spaces where Neanderthals
had already disappeared."
Dr. Ian Tattersall of the American Museum of Natural History was not
entirely joking when he suggested that few genes were exchanged
because "no self-respecting Neanderthal female would fancy a Homo
In making a case for the distinct differences between the two species,
Dr. Tattersall showed slides of upright skeletons of the two. But
skeletons are unrevealing of Paleolithic desire.
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