Rediscovering America
The New World may be 20,000 years older than experts thought
Accumulating evidence. But after years of being almost alone as a challenger of Clovis, Adovasio suddenly has company. Similar deposits are being reported by archaeologists at sites throughout the Americas, including one called Cactus Hill, in coastal Virginia. That project's leader, Joseph McAvoy of the privately supported Nottaway River Survey in Sandston, Va., can't discuss his newest findings because he's under a gag order from the National Geographic Society, which is helping pay for the excavation. But in a 1996 report, McAvoy described his discovery of possible pre-Clovis tools that Adovasio says look a lot like his at Meadowcroft.
Evidence also has shown up in Wisconsin. For 10 years, David Overstreet, director of the Great Lakes Archaeological Research Center in Milwaukee, has excavated two mammoth butchery sites that he says are at least 12,500 years old, and where stone tools lie among giant bones and long, curved ivory tusks. Nearby are bones of two more of the extinct elephants, 1,000 years older, bearing what appear to be the distinctive cut marks made by people chopping out meat for food. The roughly shaped tools look nothing like the precisely grooved Clovis points. Overstreet figures that by the time any corridor through the glaciers opened, somebody had already been living for a few millenniums along the ice front, hunting the megafauna of the plains south of it.
But the big break that persuaded many to rethink the conventional theory has come thousands of miles from Clovis in Monte Verde, Chile. There, archaeologist Tom Dillehay of the University of Kentucky has, for 20 years, been excavating wood, bone, and stone tools from rolling pasture land. Last year he was joined by a blue-ribbon group of archaeologists, including many who were skeptical of Dillehay's long-controversial assertions that the artifacts probably are at least 12,500 years old. The expert panel viewed the site and wound up agreeing with Dillehay: The tools bore no resemblance to those of the vanished Clovis culture. Dillehay and his Chilean colleagues now are planning more excavation to explore hints that people were at the site as many as 30,000 years ago.
Some scientists say one needs only to study modern Indians to conclude that their ancestors got here before Clovis time. One hint is in genetic material passed down only from mothers to offspring, called mitochondrial DNA. Such genes carry a molecular clock--if a single population splits into isolated groups, the buildup of random, but distinct, mutations allows geneticists to estimate how long the original groupings have been separated. "For the last five years, the genetic evidence has been saying early, early entry" into the Americas, says Theodore Schurr, a geneticist at Emory University in Atlanta. When Schurr counts the mutations accumulated among American Indians, the molecular data are consistent with departures from Asia between 15,000 and 30,000 years ago. The analysis revealed three distinct families of mutations common among American Indians and found elsewhere only in Siberia or Mongolia. Strangely, about 3 percent of Native Americans also have a genetic trait that occurs elsewhere only in a few places in Europe. This could mean either that some Asian populations migrated both west, into Europe, and east to the Americas, or that Ice Age Europeans may have trickled into the New World many thousands of years ago, perhaps by skirting the Arctic ice pack over the North Atlantic.
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