Fossilized footprints show humans arrived in North America much earlier than expected

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The commonly held view is that people arrived in North America Asia via Beringia, a land bridge that once connected the two continents, at the end of the Ice Age around 13,000 to 16,000 years ago. But more recent findings – and some disputed – have suggested humans may have been in North America earlier.

Now, researchers studying fossilized human footprints in New Mexico say they have the first unequivocal evidence that humans were in North America at least 23,000 years ago.

“The settlement of the Americas is one of those things that has been for many years very controversial and many archaeologists have opinions with an almost religious zeal, ”said Matthew Bennett, professor and specialist in ancient footprints at the University of Bournemouth and author of a study on the new discoveries published in the journal Science on Thursday.

“One of the problems is that there are very few data points”, he added.

‘Unequivocal’

Bennett and his colleagues were able to accurately date 61 footprints by radiocarbon dating of the seed layers of aquatic plants that had been preserved above and below them. The footprints discovered in the Tularosa Basin in White Sands National Park, were made 21,000 to 23,000 years ago, the researchers found.

The timing and location of the footprints in southwestern North America suggests humans must have been on the continent much earlier than previously thought, Bennett said. The people who made the footprints – mostly teenagers and children – lived in New Mexico during the height of the last ice age.

Between 19,000 and 26,000 years ago, a period known as the last ice maximum, two massive ice caps covered the northern third of the continent and reached south to New York, Cincinnati and Des Moines, Iowa. Ice and cold temperatures would have made travel between Asia and Alaska impossible during this time, meaning the people who left the footprints likely arrived much sooner.

“This is the first unequivocal site and a good data point that places the people of the American Southwest around the last glacial maximum,” Bennett said.

The prints were dated using seeds buried in layers of sediment below and above the prints.

“This is the important point because it allows you to look at the older sites, the more controversial sites, in a different light.”

One such site is the Chiquihuite Cave in Zacatecas, central Mexico, where man-made carved stone tools dating to 30,000 years ago have been found.

David Rachal, a geoarchaeological consultant who has worked with human and animal tracks in the Tularosa basin for eight years, said the imprint dates provided by Bennett and his team appeared “extremely strong,” with seeds providing very reliable and accurate ages through radiocarbon dating.

“Plus these dates come from seed layers above and below the track surface, which frames the track’s training event. You couldn’t ask for a better setup,” Rachal said. , who did not participate in the study.

However, he said it was surprising that no artifacts, such as stone tools, were found in the area.

“These leads suggest that people were in New Mexico much sooner than expected. It’s a theme that is gaining ground in the literature. However, we need to be careful and do more research before we start doing a lot of waving. arms, ”Rachal said.

An artist's impression of what the landscape would have looked like when the footprints were made.

Children and teenagers

The footprints were probably made in loose soil at the edge of a wetland. The wind likely blew dust across the surface, silting up the footprints, Bennett said.

The hunter-gatherers, he said, would have taken well over 10,000 steps per day, meaning that at least a few footprints would survive in the fossil record.

Footprints tell an interesting story of life during this time, with the traces left mostly by adolescents and young children.

Analysis of the footprints’ dimensions suggested they were made by children aged 9 to 14 – a pattern seen at other fossilized footprint sites. Traces of mammoths, giant land sloths, large wolves and birds are also present on the site.

“One hypothesis for this is that the division of labor, in which adults are involved in skilled tasks while collection and transport are delegated to adolescents,” the study notes.

“Children accompany adolescents and collectively they leave more footprints than those preferably recorded in the fossil record.”

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