Excavations suggest new human timeline in U.S.

Kulapavana · November 14, 2005

Southern archaeologists revise history

By MIKE TONER

The Atlanta Journal-Constitution

Published on: 11/14/05

A wave of archaeological revisionism, fueled in part by unfolding discoveries in South Carolina, is challenging long-held views about the first Americans – who they were, where they came from, when they arrived, and even what happened after they got here.

Generations of students have learned that hardy hunters — ancestors of today's Native Americans — crossed a land bridge from Siberia into Alaska as the last ice age was ending 13,000 years ago and, within several centuries, had spread out across much of North and South America.

But increasing evidence from archeological excavations and new analyses of prehistoric human migrations is testing that once widely accepted view of "coming to America."

"I think we had human activity here 40,000 to 50,000 years ago," said University of South Carolina archaeologist Albert Goodyear, who has, over the last few years, found signs of prehistoric toolmaking from deeper and deeper excavations along the Savannah River in Allendale County, S.C.

"The old ideas on New World origins are based on informed speculation and not supported by evidence," said Smithsonian Institution archaeologist Dennis Stanford. "Through time and repetition — and in the absence of clear alternatives — the theory became dogma, and ultimately ideology."

New set of questions

As doubts about the "dogma" grow, Stanford and other scientists at a recent conference in Columbia are airing a host of emerging new theories. Did they come by land or sea? And if by sea, was it via the Pacific or the Atlantic? From Siberia, or Iberia? Or perhaps by way of Australia? Did they inhabit Alaska first or the American South? Might they have been here 20,000 years ago, or even 40,000 to 50,000 years ago? Did their hunting prowess drive the woolly mammoths and other ice age "megafauna" to extinction, or were human populations decimated by some global catastrophe that also extinguished other species in North America around 12,000 years ago?

For a half century, archaeologists have held that the first Americans were the people who made a distinctive style of stone tools – broadly fluted, carefully crafted blades and projectile points first found near Clovis, N.M.

Although Clovis points have since been found throughout the country, they always occur at sites generally dated to between 12,500 and 12,900 years ago — soon after the opening of an ice-free corridor through western Canada that is thought to have provided these "first Americans" with ready access to the interior of the continent.

"Like other archaeologists, I didn't believe there was anything earlier," said Goodyear, who found a Clovis "tool factory" on a hillside near Martin, S.C. "And we didn't look for what we didn't think was there so we didn't find anything earlier."

In recent years, however, several locations along the Eastern Seaboard, in Central America, and in southern Chile have yielded archaeological evidence — some persuasive, some disputed — that humans were widely distributed in America long before Clovis technology and the people who developed it.

Sites with simpler man-made tools have been unearthed in a cave at Meadowcroft, Pennsylvania, in a sand dune at Cactus Hill, Virginia, and in a river bottom in northern Florida.

Radiocarbon dates place the presence of humans at those sites somewhere between 14,000 and 17,000 years ago.

Spurred by such discoveries, Goodyear decided to dig deeper at his site — wondering if the large outcropping of flint-like chert might have attracted people to the banks of the Savannah River in an earlier time.

The deeper he went, the further back in time he went. Over the last several years, he has unearthed what may be the oldest hints yet of humans in North America — a thin strip of burned plant material that could be an ancient hearth, and chipped and flaked chert that he believes are the oldest tools ever found in North America.

"I think we had human activity at 40,000 to 50,000 years ago," he said.

Some archaeologists have attempted to explain such dates by suggesting that there were earlier waves of immigrants from Asia who trickled down the coast of Alaska and California, perhaps even to South America.

European origins?

Genetic and linguistic similarities between today's Native Americans and the people of Siberia strongly support the notion that, at whatever time they arrived, the first Americans came from Asia.

But Stanford and Exeter University archaeologist Bruce Bradley contend that archaeological evidence of Asian origins is less convincing. They say most of the prehistoric sites in eastern Siberia, the likely jumping-off point for immigration to America, are younger than Clovis sites in America. Even more perplexing, they say, is that stone tools found in Siberia have little in common with finely crafted Clovis points.

But Stanford and Exeter say made-in-America Clovis technology does resemble stone tools of the Solutrian culture, which arose in southern France and northern Spain 15,000 to 20,000 years ago.

How did they get here? Stanford said the ice age climate was so cold that Solutrian hunters in skin or wooden boats could have easily followed seals and other game along the ice front connecting northern Europe with Labrador — perhaps reaching the shores of North America by accident.

Stanford said his theory explains why Clovis archaeological sites in the eastern United States tend to be older than those in the western states and Alaska. He thinks Clovis people moved out of the Southeast into the west and north as the ice sheets covering North America retreated.

But Stanford conceded that while the "Solutrian solution" may reveal the origins of Clovis culture, it doesn't explain the primitive tools being found in South Carolina, which — if the dates are correct and the tools really are tools — reflect human activity thousands of years earlier.

While scientists ponder where Clovis culture came from, others are trying to explain where it went. Based on the tools by which we know them, Clovis people took the country by storm in a matter of a few centuries — and then faded quickly from the archaeological record.

Richard Firestone, a nuclear scientist at the Department of Energy's Lawrence Berkeley National Laboratory, thinks that the Clovis era may literally have ended with a bang – a supernova, a star that exploded somewhere in the galactic neighborhood 41,000 years ago and unleashed a rain of cosmic debris that reached the earth about 13,000 years ago.

He said heightened levels of radiation and microscopic magnetic spherules recovered from nine Clovis sites in North America, including the one in South Carolina, suggest a major impact of space debris at about that time.

Firestone said the impact, perhaps a large comet ejected by the supernova, wasn't as big a cataclysm as the one blamed for the demise of the dinosaurs 65 million years ago, but he believes it was sufficient to disrupt human and animal life over a large part of North America.

Firestone's theory has been challenged by other physicists, but it also competes with more mundane explanations for the decline of Clovis culture.

Some archaeologists contend that the disappearance of mammoths and other big game at the end of the ice age left the hunters with nothing to hunt. Some suspect they may have failed to adapt to a changing climate, or been decimated by disease.

"The more we know, the more we realize how complex the situation is," said University of Tennessee archaeologist David Anderson. It's clear that we're going to have to start thinking of the peopling of the Americas as a process, not an event.

"The fact is that we don't have a simple story to tell, but that's what makes this an exciting time for archaeology."