Posted on Oct 7, 2023
Fossil footprints in New Mexico suggest humans have been here longer than we thought
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https://www.npr.org/2023/10/07/ [login to see] /fossil-footprints-in-new-mexico-suggest-humans-have-been-here-longer-than-we-tho
How long have humans lived on the American continent?
For decades, one prevailing answer was perhaps 14,000 years, based largely on the age of early human stone tools known as Clovis points, first discovered in Clovis, NM.
But a new analysis of fossilized human footprints adds weight to the case for a longer human history in the Americas.
The footprints are among thousands made by humans, mammoths, giant sloths and others in White Sands National Park, an ethereal landscape in southern New Mexico where waves of white gypsum dunes lap across the vast Tularosa basin.
That basin held a lake during the last Ice Age, and its dried-out banks preserve the prints.
How long have humans lived on the American continent?
For decades, one prevailing answer was perhaps 14,000 years, based largely on the age of early human stone tools known as Clovis points, first discovered in Clovis, NM.
But a new analysis of fossilized human footprints adds weight to the case for a longer human history in the Americas.
The footprints are among thousands made by humans, mammoths, giant sloths and others in White Sands National Park, an ethereal landscape in southern New Mexico where waves of white gypsum dunes lap across the vast Tularosa basin.
That basin held a lake during the last Ice Age, and its dried-out banks preserve the prints.
Fossil footprints in New Mexico suggest humans have been here longer than we thought
Posted from npr.orgPosted in these groups: State of New MexicoU.S. Geological Survey (USGS)
National Park Service
Science
National Park Service Science
Posted 7 mo ago
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PO1 William "Chip" Nagel
..."'How did people get here?'
In 2021, researchers from the National Park Service, the U.S. Geological Survey and others published a paper in the journal Science saying those footprints were between 21,000 and 23,000 years old.
That was controversial.
"These ages were really much older than the accepted paradigm of when humans entered North America," said Kathleen Springer, one of the US Geological Survey researchers who wrote the report.
She says scientists had thought humans might have crossed from what is now Siberia to Alaska toward the end of the last Ice Age. But if her team's analysis of the footprints was correct, maybe that was wrong, and humans found a way onto the continent even when its northern lands were still ice-bound.
"It opens up whole avenues of migratory pathways," she said. "How did people get here?"
The overlapping tracks – and timeline – of humans and megafauna also opened new questions about how long the species coexisted, and what role humans might or might not have played in their extinction.
Critics challenged the research. Another paper published in Science said the dating technique used was flawed: The scientists had carbon-dated seeds from Ruppia cirrhosa, a grasslike aquatic plant that lives in lakes and that was embedded along with the footprints. But aquatic plants can absorb older carbon from water, skewing the results.
So, after some pandemic-related delays, the researchers returned to the excavation site, this time to carbon-date tree pollen, for better accuracy. Also, they took samples of the lake bed.
"They're like tubes pounded in the sedimentary sequence and taken back to a laboratory and analyzed," said Springer."..
..."'How did people get here?'
In 2021, researchers from the National Park Service, the U.S. Geological Survey and others published a paper in the journal Science saying those footprints were between 21,000 and 23,000 years old.
That was controversial.
"These ages were really much older than the accepted paradigm of when humans entered North America," said Kathleen Springer, one of the US Geological Survey researchers who wrote the report.
She says scientists had thought humans might have crossed from what is now Siberia to Alaska toward the end of the last Ice Age. But if her team's analysis of the footprints was correct, maybe that was wrong, and humans found a way onto the continent even when its northern lands were still ice-bound.
"It opens up whole avenues of migratory pathways," she said. "How did people get here?"
The overlapping tracks – and timeline – of humans and megafauna also opened new questions about how long the species coexisted, and what role humans might or might not have played in their extinction.
Critics challenged the research. Another paper published in Science said the dating technique used was flawed: The scientists had carbon-dated seeds from Ruppia cirrhosa, a grasslike aquatic plant that lives in lakes and that was embedded along with the footprints. But aquatic plants can absorb older carbon from water, skewing the results.
So, after some pandemic-related delays, the researchers returned to the excavation site, this time to carbon-date tree pollen, for better accuracy. Also, they took samples of the lake bed.
"They're like tubes pounded in the sedimentary sequence and taken back to a laboratory and analyzed," said Springer."..
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