First Americans may have crossed Atlantic 50,000 years ago
By Peter N. Spotts | Staff writer of The Christian Science Monitor
In a discovery sure to set off a firestorm of debate over human migration
to
the western hemisphere, archaeologists in South Carolina say they have
uncovered evidence that people lived in eastern North America at least
50,000 years ago - far earlier than any previously known human presence.
If the results hold up, this could spur some significant rewriting of
early
human history. It adds to a growing body of evidence that human
colonization
of the Western Hemisphere is a more complicated - and much older - story
than one involving simply a land bridge from Asia.
Cracks in that theory had already begun to appear in recent years. But the
new evidence - in the form of stone tools buried deep in the South
Carolina
countryside - could be the most credible and provocative yet. Coupled with
other finds, it promises to spur inquiry into the possibility the
hemisphere's first humans may have come from Europe or Africa.
This could also put human migration to the Americas on the same time
footing
as human movement out of Africa and into Australia and Central Asia.
Lead archeologist Al Goodyear concedes that the findings of his group
won't
be accepted without debate. "I expect outright rejection of these
results,"
he said in an interview. But he still asserts that the find is "the real
deal."
The University of South Carolina archaeologist and his team uncovered what
they interpret as simple stone tools in a layer of soil far below previous
layers dated to about 16,000 years ago. "The geology and the [radiocarbon]
dates are solid" for the layer in which the simple flake tools and coring
tools were found.
The dating of the artifacts to some 50,000 years ago, announced at a press
conference Wednesday at the university, comes at a period in North
American
archaeology when researchers are still smarting from bruising battles over
evidence that humans arrived several thousand years earlier than the
so-called Clovis culture, whose artifacts date to between 10,800 and
11,500
years ago.
"This is an interesting piece of information," says Tom Dillehay, an
anthropologist at Vanderbilt University in Nashville. "It really needs to
be
compared against other available evidence. Even people with open minds
will
hesitate on 50,000 years."
Part of a larger story
Yet the South Carolina team's find is not alone in its antiquity - dates
which begin to push the radiocarbon-dating techniques used to their
limits.
One site in Oklahoma has been dated to between 30,000 and 35,000 years
ago.
Brazilian and European archaeologists are working a site in Brazil that
they
say dates to 50,000 to 60,000 years ago. And a site in Chile has yielded
artifacts dating to 33,000 years ago. In all cases, however, the evidence
has been controversial.
Researchers interested in the origins of native Americans once held that
the
first Americans crossed a land bridge between Siberia and North America,
then down into the "lower 48" through a corridor in the glaciers in the
last
ice age.
The idea evolved after unique spear points were discovered in Colorado and
New Mexico, near Clovis in the 1930s. Once people knew what to look for,
Clovis spear points began to appear throughout North America at what have
been interpreted as quarries and kill sites where hunters had brought down
their Pleistocene prey. Scientists applied radiocarbon dating techniques
to
organic material found in the same soil layers as the spear points and
found
them to be between 10,800 and 11,500 years old.
Yet several lines of argument and evidence have chipped away at the
foundations of the Clovis culture as the earliest Americans, according Dr.
Dillehay.
He notes that so far researchers have failed to find sites in Siberia with
primitive hunting technologies similar to those of Clovis people. Only one
or two Clovis habitation sites have been found, so little if anything is
known about the culture's lifestyle. As with Goodyear's site, researchers
have unearthed artifacts at eastern US sites that predate Clovis.
Genetic diversity in the Americas
A Clovis-first approach fails to explain significantly older sites in
Central and South America. And while genetic similarities between modern
native Americans and Asiatic people have been documented, the high level
of
genetic diversity seen in native Americans "is difficult to explain in a
Clovis time frame. It points to a deeper time."
These elements have undermined the Clovis-first theory sufficiently that
now
many researchers are open to the possibility that, like modern immigrants,
people came at different times and from different parts of the globe -
including Africa, Asia, Australia, and perhaps Europe. Indeed, most of the
known Clovis sites are found in the eastern US. Some researchers have
suggested that spear points found on the East Coast bear a striking
resemblance to points found in Europe, raising the possibility that Stone
Age Solutrean culture from what is now southwestern France may have made
their way west.
"The vast majority of North American archaeologists have become convinced
that Clovis doesn't explain the origins of the first people in the
Americas," says Dr. Dillehay, whose work on a 13,000-year-old Monte Verde
site in Chile was instrumental in turning the intellectual tide.
Goodyear and others agree a key point of contention will be whether the
newly dated tools are human-made. Most Clovis-era tools, and even
pre-Clovis
artifacts, are worked on both sides of the rock. The Topper artifacts are
flaked only on one side. Goodyear and others say that based on past
experience, they are convinced that the artifacts were crafted with human
hands. Critics are likely to view them as ambiguous, possibly nothing more
than naturally chipped rocks.
In 1998, Goodyear dug below the level where Clovis artifacts were found
and
found odd stone tools up to 1 meter deeper. The soils in the layer were
dated to 16,000 years ago. Last year, the team dug even deeper and found
tools, as well as charred vegetation they could used for radiocarbon
dating.
The samples were recovered at the site and prepared by Tom Stafford of
Stafford Laboratories in Boulder, Colo. The widely respected specialist
then
sent the samples to the University of California at Irvine for dating.
The resulting dates of up to 51,700 years old are minimum ages
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