COLUMN ONE : Just When Did People Get Here? : An ancient Chilean village is shaking up theories about when humans came to the Americas. This scientific treasure trove may help push back the clock in an intercontinental ‘dating game.’
Many scientists envision South America 12,000 years ago as a virgin landscape unknown to humankind. That vision is being shaken up by new evidence that people may have migrated from Asia to the Western Hemisphere much earlier than had been believed.
A theory widely accepted until recently says people first came to North America about 11,500 years ago, walking across a land bridge later consumed by the Bering Sea. They made their way south from Alaska, succeeding generations spreading across North America and then across the Central American isthmus into South America.
Now, finds at archeological sites in South America, including one called Monte Verde here in southern Chile, suggest that people arrived hundreds, perhaps thousands, of years before that.
Revisionists claim a string of finds such as Monte Verde is making us rethink the timetable for America’s first immigrants. Such reckoning also shakes theoretical pillars that have stood since the 1930s to help explain how people spread through the Western Hemisphere, colonizing two huge continents, adapting to strange terrains, climates, flora and fauna.
If Paleo-indians occupied the Americas earlier than has been supposed, basic theories about how they conquered this wild new world must be revised: what patterns their migration took, how their tools for survival evolved, what skills and knowledge they developed to live off the land in the waning stages of the last Ice Age.
At most sites dating back that far, nature has destroyed wood, animal hides and plants. But at Monte Verde, an unusual covering of peat sealed away and protected a trove of evidence. So even if the site cannot be used to pin down when people first arrived, “this is probably one of the few times, if not the only time, in the Americas that a site of the late Pleistocene has yielded this bulk and diversity of early material,” said archeologist Thomas Dillehay, who is directing research on Monte Verde.
Scientists have carefully excavated the Monte Verde encampment and studied everything they have found, from plant particles to stone projectile points to a child’s footprint in hardened clay.
The people lived in pole-frame dwelling clusters built on log foundations and partly covered with hides. Besides meat from mastodons and other animals, they ate a wide variety of fruits, nuts, mushrooms and roots, including wild potatoes. They apparently even used medicinal plants, perhaps to treat skin infections or the flu.
Studies of the material are continuing 18 years after peasant farmers uncovered the site on the banks of Chinchihuapi Creek, 20 miles southeast of the city of Puerto Montt. Such scientific work is painstaking and slow. But radiocarbon dating--analysis of sedimentary strata and long-extinct pollen samples--and other research have convinced Dillehay that the people were at Monte Verde more than 12,000 years ago.
Most of the valuable archeological material is now stored in boxes that fill a dark room on the campus of Austral University in Valdivia. University geologist Mario Pino, who keeps the room under lock and key, hopes that someday Monte Verde can be reconstructed. “We want to assemble the site again under a roof, complete,” said Pino.
Monte Verde deserves a museum. It is the most complete collection yet uncovered of evidence--still inconclusive, hard-liners argue--that people lived in South America as early as 12,000 to 13,000 before the present--”B.P.,” in the jargon of archeologists.
Such a finding would not cause as much of a fuss if the Chilean site were in the United States.
“The problem is that this is much farther south,” Pino said. “You have to add on the amount of time that the guys took to get here.”
For people to be in Monte Verde 12,000 or 13,000 years ago, their ancestors probably had to be in North America by at least 13,000 or 14,000 B.P.--at least 1,000 years before 11,500 B.P.
Most archeologists agree that humans crossed to the Americas over a neck of land later covered by the Bering Sea when melting ice raised ocean levels. Some say southward migration much earlier would have been blocked by huge ice sheets of the frigid Pleistocene epoch, which was coming to an end about 12,000 B.P.
Even many scientific hard-liners who reject pre-12,000 dates admit that people could have skirted coastlines to get around glacial sheets or even trekked over expanses of ice. But they contend that the revisionists have yet to produce unflawed evidence from enough sites to make the earlier dates irrefutable.
The horizon of 11,500 B.P. was established in the 1930s by research on early hunters who used a distinctive style of fluted spear point. These “Clovis points,” named for a site near Clovis, N.M., have been found all around the Americas. But none has been clearly associated with material dated before the Clovis horizon or “barrier.”
Because radiation deteriorates over time at a steady rate, scientists can date organic matter by measuring the radioactive carbon 14 it contains. Recent advances in radiocarbon dating have made the process more accurate, but it still is not foolproof.
Pino, a carbon-dating specialist, is part of an international team of scientists that has researched Monte Verde under Dillehay’s direction. While Dillehay, a University of Kentucky archeologist, has contributed to skirmishes over dates, he says he is not very interested in what he and some other archeologists call “the dating game.”
“I wish people would just see the site for what it is and move beyond the dating game,” said Dillehay, 45. Speaking by telephone from his Lexington, Ky., home, he described Monte Verde as a uniquely rich record of late Pleistocene people adapting to the temperate rain-forest ecology of southern South America.
An estimated 30 to 50 Monte Verdeans lived for several months in elaborate huts built on solid wood foundations beside the creek. Dillehay calls them the earliest known architects in the hemisphere.
Not only did they hunt or scavenge meat from the elephant-like mastodons, paleo-llamas and “other critters,” they used edible plants brought to camp from nearby and distant places, including a seashore 30 miles away, he said.
He said he has been especially impressed by what appears to be the presence of medicinal plants in Monte Verde. Parts of many species--and only the parts with medicinal value--were brought from remote places, he said. “These plant parts are not edible,” he said. (They are still used by local Mapuche Indians for treating such ailments as intestinal problems and skin infections.)
Dillehay said radiocarbon dating, verified by three reputable laboratories, has given dates between 12,300 and 13,500 B.P. for “demonstrable artifacts and demonstrable human presence, such as fire pits.”
By throwing out the earliest and latest dates, and averaging the most reliable ones, the ancient camp is “securely dated between 12,400 and 12,800,” he said.
It would be more secure, of course, if Monte Verde contained a human skeleton that could be carbon-dated. The problem is, Dillehay said, “there probably isn’t in all of the Americas a single reliable human skeleton in any late Pleistocene archeological site that predates, securely, 10,000 B.P.”
People of that era were mobile hunters and gatherers, he explained. “It may well be that people were simply buried along the trail, so to speak, and not in the domestic sites.”
With or without bodies, increasing evidence from other sites is being used to corroborate the Monte Verde time frame. “Like lightning bugs popping up in the night, you’ve got sites scattered all over the place,” Dillehay said.
Among the brightest is a Venezuelan coastal site called Taima-Taima. The skeletal remains of two mastodons were found there, and in the pubic area of each was a broken spearhead. Both sets of bones have been carbon-dated at about 13,000 B.P., said Alan Bryan, a University of Alberta archeologist who researched Taima-Taima.
“It has been argued that the dates must be wrong somehow,” Bryan said by telephone from Canada. “We don’t see how.”
Bryan published his findings in 1978, but his dates were not widely accepted by U.S. archeologists. Now, he said, with growing acceptance of Dillehay’s findings at Monte Verde, Taima-Taima is also gaining credibility.
Dillehay said three sites in Colombia that have received little international attention also yield promising examples of early dating. Tequendama, El Abra and Tibito were excavated by scientists from the National University in Bogota. Carbon dates, taken from bones of extinct animals associated with human activity in the sites, range from 12,000 to 14,000 B.P., Dillehay said.
In Argentina, archeologist Augusto Cardich has spent more than 20 years working on cave sites near Santa Cruz, in southern Patagonia. In one called Los Toldos, Cardich said his team from the University of La Plata has found human artifacts and food in sediment dated at 12,600 B.P.
“They were men who ate (now) extinct animals,” Cardich said.
Cliff paintings in Brazil’s northeastern state of Piaui have been radiocarbon-dated as far back as 12,000 years. And digs nearby, at a place called Pedra Furada, have produced controversial evidence of human presence that Brazilian archeologist Niede Guido claims dates from 50,000 B.P.
In North America, early sites also flicker with signs of pre-Clovis occupation, but many have been discredited because of doubts about their dating or evidence. Two new sites have just joined the “dating game”:
Jiri Chlachula, a Czech archeologist studying in Canada, has discovered human artifacts under undisturbed sedimentary strata along an eroded bank of the Bow River, where it passes through Silver Springs and Varsity Estates sectors of Calgary, Alberta. Bryan, at the University of Alberta, said Chlachula found stone fragments dated at least 21,000 years ago.
Pendejo, a cave site near Orogrande, N.M., on the Ft. Bliss military reserve, has been excavated recently by Richard McNeish of the Andover Foundation for Archaeological Research in Massachusetts. Speaking from New Mexico, McNeish said he has human hair dating from 19,000 B.P. and “human fingerprints in clay that go back to 36,000 years ago.” McNeish predicted that the three volumes he plans to publish on the site starting next fall will help lay the Clovis theory to rest.
“We’re about to put a major nail in the coffin,” he said.
Among longer-known pre-Clovis sites, one of the most widely cited examples is Bluefish Caves in the Canadian Yukon, discovered in 1975. Carbon dates taken from mammoth bones apparently used as tools there go back to before 15,000 B.P.
Dillehay said “the kingpin site that simply will not go away” in North America is Meadowcroft Rock Shelter, in southwestern Pennsylvania. Archeologist James Adovasio of Mercyhurst College in Erie has been studying Meadowcroft since 1973. A final report on the site is in production.
Adovasio said Meadowcroft and other sites investigated in the Cross Creek Drainage have produced detailed evidence of human presence in the area by 15,000 B.P. “at the latest.”
He said critics questioned the evidence, saying that the oldest layers of sediment had been “contaminated” by intruding material from upper layers.
“This was not the case,” he insisted in a telephone interview.
Adovasio complained that archeologists who teach the Clovis theory have imposed “a chronological strait jacket” on the concept of early cultural development in the Americas. But he said sites in both continents are undermining the Clovis barrier.
Revisionists like Adovasio portray “die-hard” Clovis theorists as unyielding and adamant. But Thomas Lynch, a leading skeptic on pre-Clovis findings, said he is open to solid evidence.
Lynch, who retired from teaching at Cornell University last year, said pre-Clovis evidence from most sites has been rejected because it is flawed or inconclusive. But he added: “If I were a gambler, I would bet that before I die an occupation of 12,000 to 15,000 years ago that is good will be found.”
He said Taima-Taima has some “good dates,” and “I think Meadowcroft and Monte Verde are hanging in there. Most archeologists that I respect are keeping an open mind on them.”
Other skeptics ask why there are so few pre-Clovis sites with good evidence. Brian Fagan, an archeologist at UC Santa Barbara, said early Americans probably moved often from place to place and “were very, very thin on the ground.”
“It’s not surprising we’ve found almost none of them,” Fagan said by phone. “I mean, the original population of the Americas was not in the thousands but in the hundreds.”
Rob Bonnichsen, director of the Center for the Study of the First Americans at Oregon State University, said the number of good pre-Clovis investigations is gradually rising and people such as Adovasio of Mercyhurst and Dillehay of Kentucky are successfully “dealing with the assaults by Clovis-first” archeologists.
“The Clovis ‘barrier’ has been broken,” Bonnichsen declared. “We still have pitiable few pre-Clovis sites, but these people have done it.”
Dillehay is finishing a second volume of findings on Monte Verde, to be published by the Smithsonian Institution at the end of the year. The volume is expected to deal with many of the questions raised by skeptics about dating.
“We’ve done everything we can to demonstrate that the dates are not contaminated and they are what they are,” Dillehay said.
Times special correspondent Mac Margolis in Rio de Janeiro also contributed to this report.
