NEW ANSWER TO OLD QUESTION
Proven: Man in America by 15,000 B.C.
Most people probably wouldn't have noticed it, but farmer Harold Conover in 1988 happened to see a stone spear point in the sand on a logging road near his farm in Carson, Va. Conover is not an archaeologist, but he recognized it as a Clovis spear point because there is a known Clovis site on his farm.
He tracked the point to a sand pit owned by the International Paper Co. at the Cactus Hill site, about 70 km south of Richmond, Va., overlooking the Nottoway River.
That chance discovery triggered a decade-long excavation that eventually might resolve the ongoing, often bitter controversy over when humans first migrated to North America. The spear point itself wasn't unusually old, but it led archaeologists Joseph and Lynn McAvoy to a prehistoric campsite that might be as many as 17,000 years old 5,500 years older than the Clovis sites previously thought to be the oldest on this continent.
About 57-75 cm below the surface they found a campsite containing an ancient hearth, scrapers, woodworking tools and several Clovis spear points. Radiocarbon dating of charcoal from the hearth showed it to be about 10,900 years old, appropriate for a Clovis site.
Digging further, they found a second campsite about 10-15 cm lower, again with hearths and stone tools. The tools were distinctly different. Instead of quartzite Clovis spear points, the tools from the lower camp were made of chert and were of a more primitive form called blade flakes or core blades. Radiocarbon dating revealed the hearth was at least 15,000 years old and perhaps as much as 17,000.
The findings indicate that humans have lived in North America much longer than most researchers believed, and hint that their origins might be different from what had been believed.
Other archaeologists have made claims for a number of sites in both North and South America, some apparently dating as far back as 35,000 years. The dates of those sites, however, and the validity of the artifacts found there, are disputed.
Data presented last month by Joseph McAvoy and a team of archaeologists at the Society for American Archaeology meeting in Philadelphia seem to have firmly established the age of the Virginia site, called Cactus Hill.
"This is probably some of the oldest material in North America, if not the entire New World," said archaeologist Dennis Stanford of the Smithsonian's National Museum of Natural History.
The Cactus Hill site is one of several that are overturning the long-reigning theory of how humans first came to the Americas. Archaeologists always assumed that the first inhabitants walked across the Bering Strait to Alaska when ice covered its surface about 12,000 years ago.
Those first migrants quickly moved south, expanding their presence throughout the continent within as few as 500 years. That population is termed "Clovis" because its characteristic fluted spear points and other tools were first discovered near Clovis, N.M. The distinctive Clovis spear points have since been found throughout the continent and, recently, in Northeastern Asia as well, affirming the origin of these nomadic hunters.
Some archaeologists have identified other sites, such as the Meadowcroft rock shelter in Pennsylvania and the Topper site along the Savannah River in Georgia, that appear to be pre-Clovis. Their dates, however, have not been authenticated to everyone's satisfaction.
Others have found evidence that other populations might have migrated to the continent as well. Recent studies suggest that a seafaring population worked its way down the Pacific coast, establishing villages and fishing grounds on land that is now submerged. Some archaeologists believe that the same process occurred along the Atlantic coast as well.
Still, the dates of such events are questioned, and that is why the Cactus Hill site has assumed such importance. The McAvoys and their colleagues have produced dating evidence that might well be irrefutable, thanks in part to Conover's discovery.
When skeptics scoffed at Joseph McAvoy's claim that the Cactus Hill spear points were possibly 17,000 years old, McAvoy organized a team of at least 10 specialists and spent three years "challenging the conclusions" of his original report.
Paleobotanist Lucinda McWeeney of Yale, for example, identified the species of trees that were burned in the hearths. The pre-Clovis hearth contained remnants of white pine, while the Clovis hearths contained hard Southern pine. Trees in the area now are primarily hardwood hickory and oak. That progression of species corresponds with the gradual warming of the region since the last ice age.
She also was able to show that the charcoal in the lower hearths was not produced by a forest fire.
Soil scientist James C. Baker of Virginia Tech used a technique called luminescent dating to show that the sand at the site had not been disturbed over the millennia, suggesting that perturbation of the site by water or burrowing animals had not occurred.
Others were able to demonstrate the presence of distinctive plant fossils, called phytoliths, produced when plants on the surface are damaged, as by human activity. The amounts of phytoliths spiked at the levels of the campsites. The team also found high levels of phosphates in the soil at the levels of the sites. Phosphates are the detritus of human wastes and garbage.
"To me, the evidence is irrefutable," McAvoy said.
So, who were the pre-Clovis settlers?
"My first answer would be paleo-Indians who came across the Bering land bridge" earlier than had been thought, he said.
The Smithsonian's Stanford, however, thinks the tools are remarkably similar to somewhat older tools recently discovered in Spain and France. He suggests that those proto-Spaniards might have sailed across the Atlantic 18,000 years ago or more.
Not everyone is convinced. Archaeologist David Meltzer of Southern Methodist University questions the fact that the two campsites discovered at Cactus Hill, separated in time by several thousand years, are separated in space by only 7-10 cm. "There should have been more soil-forming processes over that period," he said, so that the early site was more deeply buried.