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You may not have seen this article* but this article supports
recent discoveries which indicates that humans migrated from Africa
much later than thought.
The American Anthropological Association has created a website**
about their project Understanding Race and Human Variation. There is
an interesting graphic, created by the Science Museum of Minnesota
(who is developing the exhibition) illustrating the rich genetic
variation contain in the early African population compared to the
populations that evolved later in Eurasia, Asia and Europe..
Cheers,
Martin
*http://www.nytimes.com/2007/01/12/science/12skull.html
**http://www.understandingrace.org/humvar/index.html
January 12, 2007 NY Times
Skull Supports Theory of Human Migration
By JOHN NOBLE WILFORD
From a new analysis of a human skull discovered in South Africa more
than 50 years ago, scientists say they have obtained the first fossil
evidence establishing the relatively recent time for the dispersal of
modern Homo sapiens out of Africa.
The migrants appeared to have arrived at their new homes in Asia and
Europe with the distinct and unmodified heads of Africans.
An international team of researchers reported yesterday that the age
of the South African skull, which they dated at about 36,000 years
old, coincided with the age of the skulls of humans then living in
Europe and the far eastern parts of Asia, even Australia. The skull
also closely resembled skulls of those humans.
The timing, the scientists and other experts said, introduced
independent evidence supporting archaeological finds and recent
genetic studies showing that modern humans left sub-Saharan Africa
for Eurasia between 65,000 and 25,000 years ago; probably closer to
45,000 to 35,000 years ago for Europe.
Until now, however, paleontologists had been frustrated by the
absence of fossils to test the hypothesis of most geneticists that
the people of sub-Saharan Africa and in Eurasia at that time were one
and the same - modern humans. The human fossil record in Africa from
70,000 to 15,000 years ago had been virtually blank.
Some scientists, on the other hand, have contended that the migration
could have begun as early as 100,000 years ago and that in the
intervening time, contact with more archaic populations like the
Neanderthals could have produced recognizable changes in what became
the modern humans of Eurasia. But no scientists in the migration
debate have disputed that ancestors of the human species originated
in Africa.
In a report in today's issue of the journal Science, a research team
led by Frederick E. Grine of the State University of New York at
Stony Brook concluded that the South African skull provided critical
corroboration of the archaeological and genetic evidence indicating
that humans in fully modern form originated in sub-Saharan Africa and
migrated, almost unchanged, to populate Europe and Asia.
Dr. Grine and his colleagues said in an announcement by Stony Brook
that the skull was the first fossil evidence "in agreement with the
out-of-Africa theory, which predicts that humans like those that
inhabited Eurasia should be found in sub-Saharan Africa around 36,000
years ago."
Ted Goebel, an anthropologist at Texas A&M University who was not
connected to the research, said the skull opened the way to important
insights about "the missing years of modern humans."
Writing in an accompanying commentary in the journal, Dr. Goebel
said, "Here is the first skull of an adult modern human from
sub-Saharan Africa that dates to the critical period, and one that
can speak to the relationship of early moderns from Africa and
Europe."
The new findings pivoted on fixing the skull's age. When it was
uncovered in 1952 near the town of Hofmeyr, South Africa, the cranium
was almost complete, but the bone was degraded. Not enough carbon
remained for scientists at the time to extract a radiocarbon date.
Using new technology, Richard Bailey and other researchers at the
University of Oxford measured the amount of radiation that had been
absorbed by sand grains that had filled the braincase since its
burial. They calculated the yearly rate at which radiation had
collected in the sand and checked this with data from a CT scan of
the bone. In this way, they determined that the Hofmeyr skull
belonged to a human who lived 36,000 years ago, plus or minus 3,000
years.
Another member of the team, Katerina Harvati of the Max Planck
Institute for Evolutionary Anthropology in Leipzig, Germany, made a
detailed examination of the shapes, sizes and contours of all parts
of the skull. She compared these three-dimensional measurements with
those of early human skulls from Europe and with skulls of living
humans in Eurasia and southern Africa, including the Khoe-San,
commonly known as the Bushmen.
Because the Bushmen are well represented in the more recent
archaeological record, Dr. Harvati said, they were expected to bear a
close resemblance to the Hofmeyr skull. Instead, the skull was found
to be quite distinct from all recent Africans, including the Bushmen,
she said, and it has "a very close affinity" with fossil specimens of
Europeans living in the Upper Paleolithic, the period best known for
advanced stone tools and cave art.
"Much to my amazement," Dr. Grine said in an interview, "the skull
linked very closely with those from Europe at the time and not with
South African remains 15,000 years on."
Dr. Grine said these modern humans probably originated in East
Africa, which is rich in fossils of ancestors of the species, and
moved into Eurasia and also south to the tip of Africa.
"It would be nice," he conceded, "if we had more than one specimen."
Another report in Science describes one of the earliest occupation
sites of modern humans in Europe, at Kostenki on the Don River, 250
miles south of Moscow. Its stone and bone tools and a human figurine
appeared to have been made about 45,000 years ago, perhaps earlier
than human sites to the west.
The lead author of the report was Michael Anikovich of the Russian
Academy of Sciences. John Hoffecker of the University of Colorado, a
team member, said the small figurine might be "the oldest example of
figurative art ever discovered."
Dr. Goebel said the new research, archaeology, genetics and the
Hofmeyr skull should help explain when and how modern humans leaving
Africa spread out to different environments, which, he added, "is one
of the greatest untold stories in the history of humankind."
--
Martin Weiss, PhD
VP, Science
New York Hall of Science
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