"There's no doubt about the age -- it's 33,000 years old," Pino said of the sediment layers bearing the apparent artifacts under the knoll.
The date, which would put the occupation during a warm interlude in the ice ages, is based on radiocarbon examination of burned wood that scientists suspect came from hearths at the hunting camp. Archeologists found the charcoal in three shallow depressions lined with scorched clay. Other hints of human occupation include 24 fractured pebbles, several of which were probably flaked by people using them to cut and scrape meat, hides and plants.
When independent archeologists visited Monte Verde last year and authenticated the younger camp site, Pino said, they also examined the material from the deeper, 33,000-year-old layer. "They said there is no doubt these are real human artifacts," he said. "We were surprised. We expected another fight."
Dillehay is somewhat more circumspect. In an interview by telephone, he said: "We'll open up that level and see what's there. If the results remain ambiguous, we will have done the best we could. But I'm leaning toward accepting the antiquity of the level and the traces of human activity."
Dr. David J. Meltzer, an archeologist at Southern Methodist University in Dallas, who was a member of the review committee that endorsed the younger site, welcomes the new excavations. The older layer is "really intriguing," he said, "but we can't conclude anything about it until we have a better sense of what's there."
What is needed, Meltzer said, are excavations over a much larger area to increase the chances of finding many more artifacts and samples for radiocarbon analysis. If these support the early presence of humans at the site, he predicted, other archeologists will be quicker to accept the findings than they were with the first Monte Verde site.
"Of course, it depends on what they find," he said, "but this time archeologists wouldn't be as resistant because now they are not operating within the framework of Clovis history."
Since the 1930's discovery of distinctive spear points of the so-called Clovis hunters, nearly all archeologists staunchly held the view that the first Americans were big-game hunters who crossed the ice-covered Bering Straits between Siberia and Alaska some 12,000 to 13,000 years ago -- that is, not long before the 11,200-year-old dates of the earliest Clovis weapons. Prior to the Monte Verde breakthrough, several other presumed pre-Clovis sites had been reported, but none has yet met all the requirements to be judged an authentic human site dating earlier than the Clovis people.
Once archeologists accepted the 12,500-year date for the younger Monte Verde camp, they were forced to rethink how long people had already been in the Americas for them to have made it all the way from North America to southern Chile, 500 miles south of Santiago.
Archeologists are also puzzled by the absence so far of any confirmed human sites in North America that predate Monte Verde. The numbers of migrating human bands must have been so small, and their movements so nomadic, that they left no impression on the land -- they were "archeologically invisible."
No scholars seriously consider the possibility that the early Americans landed first in South America. All linguistic, genetic and other evidence points to the Bering Strait as the most likely point of entry.