A landmark archaeological site in Chile may be thousands of years younger than originally thought, a new study claims. If validated, the finding would upend a key piece of evidence that humans reached South America about 14,500 years ago and force a rethink of how and when the Americas were first settled.
The site, called Monte Verde, has long underpinned claims that people were living in South America more than 1,000 years before the Clovis culture, which is dated to around 13,000 years ago. But the new analysis, published March 19 in Science, suggests people lived at Monte Verde only 4,200 to 8,200 years ago.
Not everyone agrees: The archaeologist who first dated Monte Verde calls the new work a misreading of the site, and several outside experts say the evidence is not convincing.
Archaeologist Todd Surovell of the University of Wyoming in Laramie gets why there’s criticism. “In terms of understanding the peopling of the Americas, this site has been incredibly important for 30 years,” he says. “The interpretation that it is one of the oldest sites in the Americas has become a universally accepted fact…. I anticipate our work to be not only impactful but controversial.”
Surovell and his colleagues say a key to their claims is their discovery of a layer of volcanic ash at the site, which they determined was from an eruption of the Michinmahuida volcano in Patagonia about 11,000 years ago. The team says the ash layer is beneath the evidence of human occupation and must have predated it.
“Some archaeologists will say our findings change everything about our understanding of the peopling of the Americas, [but] some archaeologists will tell you it hardly changes anything,” Surovell says. “I think that disagreement speaks to the nature of the discipline and really shows how much we don’t know.”
The Monte Verde site was discovered in late 1975, about 800 kilometers south of Santiago. Excavations, led in part by anthropologist and archaeologist Tom Dillehay then at the Universidad Austral de Chile, revealed remarkably well-preserved pieces of wood, leather, rope, plant fibers and the remains of wooden huts that had been buried in a peat bog at the swampy location. Those finds led Dillehay, now at Vanderbilt University in Nashville, and his colleagues to report in 2008 that people were living at Monte Verde between 13,980 and 14,220 years ago. (Dillehay later updated the age to about 14,500 years ago.)
That put Monte Verde’s occupation at roughly 1,500 years before what was until then thought to be the oldest evidence of people in the Americas. That evidence — including spear points and butchered mammoth remains — comes from archaeological sites near the small New Mexico city of Clovis, which have been dated to about 13,000 years ago. The idea that people were in South America “pre-Clovis,” based mainly on the findings from Monte Verde, has since become a central tenet of archaeology in the region.
Surovell and colleagues’ new study suggests that wood and other organic material thought to show “pre-Clovis” people living at Monte Verde had been washed down by a creek at the site into lower levels of sediments, which made them seem older than they really were. Instead, radiocarbon dating of nearby sediments and studies using optically stimulated luminescence (which can date mineral grains) indicate that the site is between 4,000 and 8,000 years old — placing it firmly in the “post-Clovis” era, Surovell says.
The new findings directly challenge Dillehay’s work and the idea of the “pre-Clovis” peopling of South America. “There are other sites that have been proposed to be pre-Clovis, but none of them are terribly convincing,” Surovell says.
But Dillehay thinks the new findings are flawed. “The study contains many methodological and empirical errors,” he wrote in an emailed statement, noting that the data were “a mixture of inventions and misunderstandings” and that “the authors present a morass of largely unintegrated and contradictory data.”
The researchers, he says, took samples from locations that were not part of the original study, and spent only a few hours at Monte Verde — not enough time to properly research the complex geological, ecological and paleoenvironmental processes there: “We stand by our work, which is highly regarded and has stood the test of time.”
Geoarchaeologist Michael Waters of Texas A&M University in College Station also says the new study “falls short.” The researchers argue that the Monte Verde site dates to the middle Holocene Period, but don’t demonstrate that in the paper, he says, noting that the arrangement of sediment layers proposed in the paper isn’t possible. “I don’t know how they overlooked that. I’m kind of shocked,” he says.
Archaeologist Jon Erlandson, an emeritus professor at the University of Oregon in Eugene, echoes some of the critiques, saying that the latest study doesn’t fully address all the details recorded at Monte Verde. While some “old wood” might have been redeposited by the creek, “the authors can’t prove there was 11,000-year-old volcanic ash directly beneath the artifacts and features excavated by Dillehay’s team,” he says. “I’m not convinced.”
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