A new analysis of archaeological sites in the Americas challenges relatively new theories that the earliest human inhabitants of North America arrived before the migration of people from Asia across the Bering Strait. Conducted by University of Wyoming Professor Todd Surovell and colleagues from UW and five other institutions, the analysis suggests that misinterpretation of archaeological evidence at certain sites in North and South America might be responsible for theories that humans arrived long before 13,000-14,200 years ago. Show The researchers' findings appear today in PLOS One, a journal published by the Public Library of Science. The paper 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 Beringia land bridge up to 14,200 years ago, and then dispersed southward between two large glaciers that then covered much of the continent. The conclusions of Surovell and colleagues are based on an analysis of buried archaeological deposits, using a new statistic called the Apparent Stratigraphic Integrity Index they developed. While the stratigraphic integrity of early archaeological sites in Alaska is high -- producing strong evidence in support of unambiguous human occupation -- the sites in more southern locations pointing to possible earlier human occupation show signs of artifact mixing among multiple time periods. "If humans managed to breach the continental ice sheets significantly before 13,000 years ago, there should be clear evidence for it in the form of at least some stratigraphically discrete archeological components with a relatively high artifact count. So far, no such evidence exists," Surovell and colleagues wrote. "(Our) findings support the hypothesis that the first human arrival to the New World occurred by at least 14,200 years ago in Beringia and by approximately 13,000 years ago in the temperate latitudes of North America. Strong evidence for human presence before those dates has yet to be identified in the archaeological record." Specifically, the new analysis compared the stratigraphic integrity of three sites argued to contain evidence of earlier human occupation -- two in Texas and one in Idaho -- with the integrity of sites in Alaska, Wyoming and Pennsylvania. The three sites claimed to be older than 13,000 years ago all showed patterns of significant mixing, while the others did not. The researchers were unable to obtain detailed information about some other sites in North and South America purported to contain evidence of human occupation before 13,000 years ago. "Sites claimed to be 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 status of available data regarding these sites, we must question whether there are any sites in the Americas south of the ice sheets that exhibit an unambiguous and stratigraphically discrete cultural occupation with sufficient numbers of artifacts of clear human manufacture." The paper doesn't 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 would be expected to have large numbers of artifacts. "That they did so in Beringia but failed to do so south of the continental glaciers suggests that either there was something fundamentally different about pre-Clovis human behavior and/or geomorphology south of the ice sheets, or that the evidence indicating the presence of humans south of the ice sheets has been misinterpreted," the researchers wrote. "At a minimum, it shows that, when stratigraphically discrete occupations are not present, additional studies must be performed to demonstrate that stratigraphic integrity of association between artifacts and dated strata exist." Joining Surovell in the research were UW colleagues Sarah Allaun, Robert Kelly, Marcel Kornfeld and Mary Lou Larson; Wyoming State Archaeologist Spencer Pelton; 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. Story Source: Materials provided by University of Wyoming. Note: Content may be edited for style and length.  Evidence of very early occupation has been found in the cave in Chiquihite, central Mexico. A decade of archaeology has uncovered a 'failed colonisation' - one that has left no genetic link to the First Peoples of the Americas Share ThisHomeNewsThe earliest Americans arrived in the New World 30,000 years ago People travelled by boat to North America some 30,000 years ago, at a time when giant animals still roamed the continent and long before it was thought the earliest arrivals had made the crossing from Asia, archaeological research reveals today. Researchers from the University of Oxford have published a study, showing important new insights into our understanding of these ‘First Americans’, who made the journey from eastern Eurasia before the last Ice Age. And it reveals that the arrival of humans in numbers coincided with the ‘catastrophic decline’ in now-extinct large animals, including camels, horses and mammoths.
Based on a powerful statistical approach, the international team, led by Oxford’s Professor Tom Higham, Director of the Oxford Radiocarbon Accelerator Unit, School of Archaeology, was able to build a chronological framework for the arrival of humans into North America – and their dispersal across the continent. This showed that people were present long before previous estimates - before, during and after the ‘Last Glacial Maximum’, the peak of the Ice Age, when temperatures fell to their lowest for tens of thousands of years. But, the research, also shows that they must have come by sea, rather than across a land bridge. According to Professor Higham, ‘A combination of new excavations and cutting-edge archaeological science is allowing us to uncover a new story of the colonisation of the Americas. The First Americans came from eastern Eurasia, and it looks as though there was a surprisingly-early movement of people into the continent. ‘The people that travelled into these new lands must have come by boat, because the northern parts of North America were impenetrable and sealed off from eastern Eurasia by a massive ice sheet until 13,000 years ago.
‘The discovery that people were here more than 30,000 years ago raises a range of key new questions about who these people were, how they lived, how widespread they were and, ultimately, what their fate was.’ In addition, when the timeline for humans was compared with dates obtained for extinct animals, the analysis showed human expansion, during this warmer period, happened at broadly the same time as their disappearance. The team suggests an increase in human population seems to be linked to a significant impact on the catastrophic decline of these large megafauna. One of the team, Dr Lorena Becerra-Valdivia (now with the University of New South Wales), says, ‘The peopling of the Americas was a complex and dynamic process...What is clear is that humans were present in the continent well before previously accepted dates. But it was only around 14,700 years ago that those people became more highly visible in the archaeological record, likely due to an increase in population.’
Alongside this research, another team, led by Dr Ciprian Ardelean, from the University of Zacatecas, Mexico, and the University of Exeter, has disclosed the results of a decade of excavation of a high-altitude cave in Chiquihite, central Mexico. The cave has shown occupation earlier than anything previously known and, according to Dr Ardelean, ‘It seems likely to us that the people of Chiquihuite represent a ‘failed colonization’, one which may well have left no genetically detectable heritage in today’s First Americans’ populations.’ Dr Jean-Luc Schwenniger, who heads Oxford’s Luminescence Dating Laboratory at the School of Archaeology, notes, ‘Our involvement in the dating of this extraordinary site stretches back almost ten years and finally to see the results published is immensely satisfying...the publication of these new discoveries and findings, which rock and challenge long established views, required extra amounts of diligence, scrutiny, patience and perseverance.’ The Oxford results are based on hundreds of dates obtained from 42 archaeological sites in North America and Beringia (the ancient land bridge connecting the continent to Asia). The team used a statistical approach known as Bayesian age modelling performed on software (OxCal) developed in Oxford by Professor Christopher Bronk Ramsey. The analysis estimates the start of human occupation at different sites, as well as the commencement of three distinct stone tool traditions in these regions. Dates were combined statistically along with stratigraphic information from the deposits to estimate the start and end of human occupation at each of the sites and then plotted spatially across the continent. The Oxford work was funded by the Natural Environment Research Council (NERC; grant NF/2017/1/2), Merton College, Santander, and the Clarendon Fund. The latter also provided the funding for the paper titled, “The timing and impact of the earliest human arrivals in North America”. LatestWhat is the leading theory to how humans came to inhabit the North American continent?In the 1970s, college students in archaeology such as myself learned that the first human beings to arrive in North America had come over a land bridge from Asia and Siberia approximately 13,000 to 13,500 years ago.
What theories explain how the first people arrived in the Americas?The Bering Land Bridge has been the longstanding theory because that's the clearest connection between Asia and North America, up in the Arctic, and it only appears when ice is locked up on land and sea levels drop. It's the only place where you could walk from one side to the other.
What are the possible theories of the first human migration to the Americas?The conventional thought has been that the first migrants who populated the North American continent arrived across an ancient land bridge from Asia once the enormous Cordilleran and Laurentide ice sheets receded to produce a passable corridor nearly 1,000 miles long that emerged east of the Rocky Mountains in present- ...
When did humans first come to the Americas?When did humans settle in North America? 20,000 years before we once thought, study says. Mammoth remains found in 2013 in New Mexico suggest humans settled in North America about 37,000 years ago. The discovery means humans might have been in North America 20,000 years before scientists previously thought.
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What is the leading theory about how early humans arrived on the American continents
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