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Ancient tools and bone found in Florida could help rewrite the story
of the first Americans
By Sarah Kaplan May 13
Thousands of years ago, some of the first Americans knelt beside a
pond in what is now Florida. Clutching sharp stone knives, they hacked
at the tusk of a slain mastodon, slicing meat away from the long bone.
Then, with their work completed, they got up and walked away, leaving
behind some tools and the stripped carcass .
Centuries passed. Sea levels rose. The ancient site was submerged by
layers of sediment, and then by a rising river. Wave after wave of
human inhabitants came and went: hunters, farmers, explorers,
colonizers, retirees from New York. Until, in 2012, a team of
archaeologists descended into the river's murky depths to dig up the
artifacts below.
The ancient tools and bone are 14,550 years old, they reported Friday
in the journal Science Advances, making them the most ancient human
remnants ever found in the southeastern United States. The researchers
say the find is unequivocal proof that people were in Florida more
than 1,000 years earlier than anyone had imagined — a discovery that
could help rewrite the history of humans on the continent.
The new study comes as something of a vindication for the swampy site
in the Florida panhandle, named Page-Ladson for the diver who
discovered it and the family whose land it is on. In the 1980s,
archaeologist James Dunbar and paleontologist David Webb dug up the knife-scarred mastodon tusk that had been left there and estimated it
to be more than 14,400 years old.
But the anthropological community was quick to cast doubt on that
date. For half a century it had been assumed that the Clovis people —
skilled hunters famous for their distinctive fluted spear points —
were the first to migrate from Asia and then down through Canada after
the glaciers began to melt at the end of the last ice age, roughly
13,000 years ago.
The age given for the tusk didn't fit that paradigm, other scientists
said — the ice-free corridor wouldn't even have been open yet.
Something must have gone wrong with the dig or the radiocarbon dating,
or perhaps the marks on the tusk were caused by something other than a
human. Even Dunbar and Webb expressed some misgivings about their
results.
"I always felt that Dunbar and Webb had been kind of maligned," said
Mike Waters, the director of the Center for the Study of the First
Americans at Texas A&M and a principal investigator on the latest
Page-Ladson report. "So when I was given the chance to go back there,
I jumped at it."
This time, Waters and his colleagues were armed with dating techniques
orders of magnitude more precise than their predecessors'. They also
had an increasingly compelling case for "pre-Clovis" occupation of the Americas: genetic analyses showing that Native Americans' ancestors
arrived here some 16,000 years ago and archaeological sites as
far-flung as Oregon and Chile bearing evidence of human presence long
before Clovis.
"What we tried to do at Page-Ladson is make a really strong case that
would be unassailable ... that these artifacts are man-made and
they're exactly where those people left them 14,550 years ago," Waters
said.
[Surprising infant grave may solve the mystery of North American
migration]
The project involved years of painstaking excavation in the Aucilla
River, a slow-moving, coffee-colored waterway shaded by cypress trees
and inhabited by alligators. Underwater archaeologists dug up and
dated layer after layer of sediment from the river bottom, sifting
through each patch of dirt for evidence that humans had once been
there.
They uncovered what co-author Tom Stafford calls a "chronological
layer cake." More than 70 samples of ancient organic material taken
from the site and radiocarbon dated at Stafford's lab showed that each
layer was slightly older than the one before it. They prove that
nothing had disturbed or mixed up the sediments as they were laid down
over time.
By the time archaeologists reached the 14,500-year-old stratum, they
began to find objects they say could only have come from humans: five
sharpened rocks that were carried in from elsewhere in the region, and
a double-sided stone knife, or biface, that would have been among the
most advanced technologies of the time. The team then re-examined the
mastodon tusk found by Webb and Dunbar (who was also part of this
excavation) and determined that it was most likely butchered by
humans.
"It's really exciting," said Jessi Halligan, an archaeologist at
Florida State University and Waters's fellow principal investigator.
"We have these unambiguous cultural artifacts found in an intact
geological stratum that dates to more than 1,500 years older than
Clovis. That's why it's a big deal. That's why we have to revisit our
theory for how the Americas were colonized."
[Girl’s 12,000-year-old skeleton found in cave may solve mystery of
Native American origins]
Donald Grayson, an anthropologist at the University of Washington who specializes in American prehistory, noted that there's some doubt
about radiocarbon dates coming out of the Aucilla River. Ancient
carbon dissolved in the water can contaminate samples, causing them to
appear older than they really are.
Halligan countered that the dates coming out of Stafford's lab match
what is known about environmental changes at the time. For example, a
layer of rapidly deposited dirt was estimated to have been laid down
between 14,500 and 14,000 calendar years before present — at exactly
the time that rising sea levels would have caused a huge influx of
sediment. If the samples were contaminated, that wouldn't be the case.
"These are the most precise ages we can get," she said.
The discovery also jibes with other pre-Clovis archaeological finds
across the Americas, including the more than 14,300-year-old Paisley
Caves site in south-central Oregon. Dennis Jenkins, an archaeologist
for the Museum of Natural and Cultural History at the University of
Oregon who co-led excavations of the caves, said that report offered
"yet another data point" in favor of an increasingly popular new
theory about America's first humans.
"I believe that the majority of professional archaeologists have
reached a point that, yes, they agree there was something here a
minimum of 1000 years before Clovis ... and since the ice free
corridor wasn't open yet, obviously there are a lot implications for
getting people down from the interior of Alaska," Jenkins said.
A member of the team, Valérie Brosseau of the University of Toronto,
makes final preparations before her descent. (Brendan Fenerty)
It seems likely that the first Americans sailed down the Pacific
coast, where pockets of land and seal-rich seas would have sustained
them as they migrated south to places like Paisley Caves and Monte
Verde in Chile. From there, they may have followed America's river
systems to the other side of the continent, or trekked across Central
America at its narrowest point and sailed up into the Gulf of Mexico.
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The Page-Ladson find also challenges another piece of anthropology
orthodoxy: Scientists have long-believed that the arrival of human
hunters in the Americas precipitated a "blitzkrieg" extinction of the
region's megafauna — mammoths, giant bison, ground sloths, and others
— because Clovis points appear at exactly the moment in the
archaeological record where giant mammal fossils vanish. But the
discovery of tools and a butchered mastodon bone suggest that humans
and these large animals co-existed for at least 1,500 years.
So, how did the Page-Ladson people get to Florida? And what happened
when they arrived?
"We just don't know yet," Waters said. "But what we do know now is
that there were people at Page-Ladson 14,550 years ago ... and I'm
hoping that it will blow the fence sitters off on to the pre-Clovis
side and maybe it will open the eyes of the Clovis First proponents."
"And then," he added, "we can start looking for answers to all those
other questions."
https://www.washingtonpost.com/news/speaking-of-science/wp/2016/05/13/ancient-tools-and-bone-found-in-florida-could-help-rewrite-the-story-of-the-first-americans/
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