New analysis confirms that fossil human footprints in New Mexico are probably the oldest direct proof of human presence within the Americas, a discovering that upends what many archaeologists thought they knew about when our ancestors arrived within the New World.
The footprints have been found on the fringe of an historic lakebed in White Sands Nationwide Park and date again to between 21,000 and 23,000 years in the past, in response to analysis published Thursday within the journal Science.
The estimated age of the footprints was first reported in Science in 2021, however some researchers raised considerations concerning the dates. Questions targeted on whether or not seeds of aquatic crops used for the unique relationship might have absorbed historic carbon from the lake — which might, in idea, throw off radiocarbon relationship by 1000’s of years.
The brand new examine presents two extra traces of proof for the older date vary. It makes use of two fully totally different supplies discovered on the website, historic conifer pollen and quartz grains.
The reported age of the footprints challenges the once-conventional knowledge that people didn’t attain the Americas till a couple of thousand years earlier than rising sea ranges coated the Bering land bridge between Russia and Alaska, maybe about 15,000 years in the past.
“It is a topic that’s at all times been controversial as a result of it’s so important — it’s about how we perceive the final chapter of the peopling of the world,” stated Thomas City, an archaeological scientist at Cornell College, who was concerned within the 2021 examine however not the brand new one.
Thomas Stafford, an impartial archaeological geologist in Albuquerque, New Mexico, who was not concerned within the examine, stated he “was a bit skeptical earlier than” however now’s satisfied.
“If three completely totally different strategies converge round a single age vary, that’s actually important,” he stated.
The brand new examine remoted about 75,000 grains of pure pollen from the identical sedimentary layer that contained the footprints.
“Courting pollen is arduous and nail-biting,” stated Kathleen Springer, a analysis geologist at america Geological Survey and a co-author of the brand new paper. Scientists imagine radiocarbon relationship of terrestrial crops is extra correct than relationship aquatic crops, however there must be a big sufficient pattern dimension to investigate, she stated.
The researchers additionally studied amassed harm within the crystal lattices of historic quartz grains to supply an age estimate.
Historic footprints of any type — left by people or megafauna like massive cats and dire wolves — can present archaeologists with a snapshot of a second in time, recording how folks or animals walked or limped alongside and whether or not they crossed paths. Animal footprints have additionally been discovered at White Sands.
Whereas different archeological websites within the Americas level to related date ranges — together with pendants carved from giant ground sloth remains in Brazil — scientists nonetheless query whether or not such supplies actually point out human presence.
“White Sands is exclusive as a result of there’s no query these footprints have been left by folks, it’s not ambiguous,” stated Jennifer Raff, an anthropological geneticist on the College of Kansas, who was not concerned within the examine.
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