Re: OT: Expelled, the movie
- From: Travel <nine510@xxxxxxxxx>
- Date: Sun, 11 May 2008 13:38:33 -0500
Even in this left wing source:
"In the other model, stoutly defended by some prominent scientists,
modern humans are seen as arising virtually simultaneously and
independently in different places in Africa, Europe and Asia."
This didn't get much play...
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Sunday, May 11, 2008
ScienceWorld U.S. N.Y. / Region Business Technology Science Health
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Fan Debate on Human Origins
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DiggFacebookMixxYahoo! BuzzPermalinkBy JOHN NOBLE WILFORD
Published: February 14, 1989
LEAD: NEW fossil discoveries and genetic evidence have fueled a
resounding debate among anthropologists over the timing and
circumstances of the last major event in human physical evolution, the
emergence of the anatomically modern Homo sapiens.
NEW fossil discoveries and genetic evidence have fueled a resounding
debate among anthropologists over the timing and circumstances of the
last major event in human physical evolution, the emergence of the
anatomically modern Homo sapiens.
One view, which is gaining adherents, holds that modern humans evolved
in one place -almost invariably identified as Africa - and then
migrated elsewhere and, in response to various regional conditions,
gradually developed slight racial differences. In the other model,
stoutly defended by some prominent scientists, modern humans are seen
as arising virtually simultaneously and independently in different
places in Africa, Europe and Asia.
No one is disputing the substantial evidence that the earliest human
ancestors evolved in Africa, with the ape-men two million to three
million years ago, and that some of their more adventurous descendants,
Homo erectus, spread through the warmer regions of the Old World. At
issue, instead, is when, where and how their descendants, archaic Homo
sapiens, made the fateful transition to thoroughly modern humans.
There is no question, either, that all modern races are members of the
same species, Homo sapiens sapiens, with the same fundamental genetic
But new fossil findings in an Israeli cave, showing that modern-looking
Homo sapiens lived in the Middle East as long ago as 92,000 years, are
being cited as support for the out-of-Africa theory. Proponents of this
theory say that these cave people were most likely the descendants of
original modern Homo sapiens who had migrated from Africa.
According to this interpretation, the findings also threaten to
displace the Neanderthals, a type of archaic Homo sapiens, from a
central place on the human family tree.
The Neanderthals, whose fossil remains were the first humanlike ones to
be unearthed, lived across Europe, in the Middle East and as far east
as Uzbekistan in central Asia from about 125,000 to 30,000 years ago,
when they mysteriously disappeared. They were the cavemen of popular
lore, stooped and brutish, but some scientists in recent decades had
come to think of them as much less primitive beings and likely close
relatives, perhaps even direct ancestors, of modern humans.
But fossils from another Israeli cave show that Neanderthals inhabited
the area as recently as 60,000 years ago, raising doubt whether they
could have been the ancestors of modern Homo sapiens who were present
30,000 years earlier. Proponents of the out-of-Africa hypothesis
contend that this discovery supports their view that Neanderthals were
a distinct and parallel species that came to a dead end and, therefore,
played no role in modern human evolution. Evidence 'Favors African
Christopher B. Stringer and Peter Andrews, paleontologists at the
British Museum of Natural History in London, writing last year in the
journal Science, fueled the controversy by asserting that the
collective evidence now ''favors a recent African origin of Homo
Nothing of the kind, counters Milford Wolpoff, a professor of
anthropology at the University of Michigan, who is an unbending
advocate of the multi-regional model. The African model, he argues,
overlooks marked paleontological evidence of anatomical features of
Neanderthals and other regional archaic Homo sapiens that persists in
early modern humans, indicating considerable interbreeding and hence
suggesting that the two branches could not be too dissimilar. Apparent
similarities between the cultural aspects of the Neanderthals and the
anatomically modern humans also testify to a close relationship, Dr.
Wolpoff says. For example, the two groups used similar stone tools and
practiced ritual burials of their dead.
In an assessment of the conflicting theories, Fred H. Smith, a
professor of anthropology at the University of Tennessee at Knoxville,
agreed that ''reasonable'' transitional fossils and archeological
samples like tools exist outside Africa. For this and other reasons, he
and colleagues conclude, in a study to be published later this year,
that multi-regional evolution ''is the best explanation for modern
human origins.'' Dating of Flint
But Dr. Smith cautioned that the data so far are not sufficiently
unequivocal to warrant dogmatic assertions by either side in the
''People are going mad,'' said Ofer Bar-Yosef, a professor of Old World
Paleolithic archeology at Harvard University, commenting on the growing
The debate came to a boil last year with a report that modern-looking
Homo sapiens lived in the Middle East as long ago as 92,000 years
-50,000 years earlier than had been estimated.
The date was established by a technique called thermoluminescence,
which is mainly used to date pottery. Flint found in the Qafzeh cave
near Nazareth in Israel was heated to release the energy of electrons
trapped inside since the stone chips were last burned long ago,
presumably when they fell from the hands of toolmakers into a campfire.
Analysis of the light emissions determined when the burning last
occurred, and since the skulls of modern humans were found in the same
sediments, it was concluded that these people had occupied the cave at
the same time.
The dating was conducted by a team of French and Israeli scientists
headed by Helene Valladas, a physicist at the Institute for Low-Level
Radiation in Gif sur Yvette, France. Most scientists have accepted the
reliability of the 92,000-year date.
This was good news for the out-of-Africa forces. If modern humans
evolved in Africa, the oldest fossils with modern features would be
expected to be found in or near Africa. Some such fossils have been
excavated in South Africa, at the Border Cave and Klasies River Mouth
sites, and have been dated at about 100,000 years. But many
anthropologists dispute the validity of these findings and say it is
difficult to put a date on the earliest modern humans in Africa any
more precise than somewhere between 40,000 and 100,000 years.
Even Dr. Stringer, a leader of the out-of-Africa school, conceded that
it remains unclear why it then apparently took 50,000 years for the
Qafzeh people to spread into Europe and eastern Asia. And Dr. Smith
noted that there is no known compelling reason - population pressures
or marked changes in technology or food supply - for African
populations to have left their homeland about 92,000 years ago.
For that matter, Dr. Wolpoff asks, why assume that the Qafzeh people
originated in Africa? ''If that date's correct, it means that Eden may
not be in Africa,'' he said. ''It might also be right back where the
According to the model proposed by Dr. Wolpoff and others, the early
Homo erectus hominids spread out of Africa more than a million years
ago. Then regional groups living in relative isolation slowly evolved
into several archaic versions of Homo sapiens, one of these being
Neanderthals. There must have been some ''gene flow'' from mixing of
these regional populations, anthropologists say, or else they might
have evolved into distinct species. Driven to Extinction
The opposing theory holds that the modern species developed in Africa
and moved into the rest of the world. People like the Neanderthals were
driven to extinction.
Out-of-Africa theorists have gained valuable support from molecular
biologists who are adept at tracing genetic lineages. Their research,
reported two years ago, showed that every person living today can trace
his or her maternal ancestry to one woman who lived in Africa 100,000
to 200,000 years ago.
Allan C. Wilson and Mark Stoneking of the University of California at
Berkeley and Rebecca L. Cann of the University of Hawaii deduced the
''African Eve'' by studying a key set of genes, mitochondrial DNA,
passed down only from mothers to their children. They examined these
inherited genes from native Africans and people in the United States
whose ancestors were African, Asian, European or aboriginal Australian.
Finding a greater number of mutations in the genes from people of
African descent, the scientists concluded that Africans have been
diversifying longer and, therefore, represented the earliest modern
branch of the family tree. In a computer analysis of the mutation
rates, they determined when the last common ancestor of all people had
lived in Africa.
Dr. Stringer and Dr. Andrews, in arguing their African-origin theory,
put great store in these findings.
But other researchers have produced results indicating that the common
ancestor might have been Asian. ''There is still much disagreement
among the experts about what the genetic data can and do tell us about
modern human origins,'' Dr. Smith and his colleagues observed. An Issue
A second discovery in Israel, at Kebara Cave at Mt. Carmel, is critical
to the debate. There scientists found skeletons identified as
Neanderthal and dated at 60,000 years.
Some anthropologists point out that the timing makes it difficult to
explain how the Neanderthals could have evolved into modern humans. The
fact that Neanderthals and modern humans probably co-existed there and
elsewhere in Eurasia for thousands of years casts doubt on any
ancestor-descendant relationship and makes it more likely that the two
were separate species.
Examination of the Kebara skeletons by Yoel Rak, a professor of anatomy
and human evolution at Tel Aviv University, revealed striking
differences in the structure and orientation of the sockets into which
the thigh bones fit. They face sideways more than in modern Homo
sapiens, which Dr. Rak and associates attributed to differences in
''locomotion and posture-related biomechanics.'' These and other
anatomical features, he said, convinced him that Neanderthals were a
Whatever their biological relationship, the Kebara Neanderthals and the
Qafzeh modern humans were leading lives of remarkable similarity. ''We
found the same archeological indicators - stone tools, hearths,
burials, use of ochre in body painting - in both sites,'' Dr. Bar-Yosef
To Dr. Bar-Yosef, among other out-of-Africa advocates, the findings
showed that different species could develop some of the same
technologies and cultural attributes, which would mean that these are
not necessarily reliable indicators of close biological affinity. To
Dr. Wolpoff the cultural similarities strongly suggest that the
Neanderthals and early modern humans were no more than different races
of the same species and interbred to produce the line of fully modern
Perhaps the picture is much more complex than imagined in either
theory, as Dr. Bar-Yosef suggested.
''Modern Homo sapiens may have emerged more than once,'' he said.
''Many populations in prehistoric times were small and struggled and
failed and just died out. We have a tendency, because we want to tell a
story, to make up a story that sounds like a continuum. Some of the
modern-looking humans we find 92,000 years ago may have been
unsuccessful. Maybe there have been many more branches along this
evolutionary tree. We need to know more about this and about the
chronology of these evolutionary events. Then we can fight over
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