A new analysis of archaeological sites in the Americas challenges relatively new theories that the first human inhabitants of North America arrived before the migration of people from Asia across the Bering Strait. Led by Professor Todd Surovell of the University of Wyoming and his colleagues at UW and five other institutions, the analysis suggests that misinterpretation of archaeological evidence at some sites in North and South America could be responsible for theories that humans arrived long before 13,000 to 14,200 years ago.
The researchers’ findings appear today in PLOS A, a journal published by the Public Library of Science. The document is the latest development in the debate over the peopling of the Americas, in which some are now questioning the long-held consensus that the first Americans were hunter-gatherers who entered North America from Asia via the bridge. land of Beringia up to 14,200 years ago. ago, then dispersed south between two large glaciers which then covered much of the continent.
Surovell and his colleagues’ conclusions are based on an analysis of buried archaeological deposits, using a new statistic called the Apparent Stratigraphic Integrity Index that they developed. While the stratigraphic integrity of early archaeological sites in Alaska is high – yielding strong evidence in support of unambiguous human occupation – sites further south, indicating possible earlier human occupation, show signs of mixing artefacts between several periods.
“If humans managed to break through the continental ice sheets in any significant way before 13,000 years ago, there should be clear evidence in the form of at least a few stratigraphically discrete archaeological components with a relatively high number of artifacts So far, no such evidence exists,” he added. Surovell and his colleagues wrote. “(Our) findings support the hypothesis that the first human arrival in the New World occurred at least 14,200 years ago in Beringia and around 13,000 years ago in the temperate latitudes of North America. Solid evidence of human presence before these dates has yet to be identified in the archaeological record.
Specifically, the new analysis compared the stratigraphic integrity of three sites thought to contain evidence of previous human occupation – two in Texas and one in Idaho – with the integrity of sites in Alaska, Wyoming and Pennsylvania. . The three sites allegedly older than 13,000 years ago all showed significant mixing patterns, while the others did not.
Researchers were unable to obtain detailed information on some other sites in North and South America believed to contain evidence of human occupation earlier than 13,000 years ago.
“Sites allegedly older than 13,000 years ago are few, and data supporting their status as sites have been poorly disseminated,” Surovell and colleagues wrote. “Given the state of available data regarding these sites, we must ask whether there are sites in the Americas south of the ice sheets that exhibit unambiguous and stratigraphically discrete cultural occupation with sufficient numbers of artifacts from clear human fabrication.”
The article does not completely rule out the possibility that humans colonized the Americas at an earlier date. “But if they did, they should have produced stratigraphically discrete occupation surfaces, some of which should contain large numbers of artifacts.
“The fact that they did it in Beringia but failed to do it south of the continental glaciers suggests either that there was something fundamentally different about pre-Clovis human behavior and/or or the geomorphology south of the ice sheets, or that evidence indicating the presence of humans south of the ice sheets has been misinterpreted,” the researchers wrote. “At a minimum, this shows that where stratigraphically discrete occupations are not present, additional studies need to be performed to demonstrate that the stratigraphic integrity of the association between artifacts and dated strata exists.”
Joining Surovell in the research were UW colleagues Sarah Allaun, Robert Kelly, Marcel Kornfeld and Mary Lou Larson; Spencer Pelton, Wyoming State Archaeologist; Barbara Crass and Charles Holmes, of the University of Alaska-Fairbanks; Joseph Gingerich of Ohio University and the Smithsonian Institution’s National Museum of Natural History; Kelly Graf of Texas A&M University; and Kathryn Krasinski and Brian Wygal, both of Adelphi University.
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