These Footprints Challenge Theory of First Americans

Skeptics will have a harder time doubting the existence of humans in North America more than 20,000 years ago following an expanded look at footprints left by a group along the shores of an Ice Age lake in what is now New Mexico. A 2021 study dating seeds embedded in the prints at White Sands National Park to between 21,000 and 23,000 years old has drawn many critics as the scientific consensus has long been that humans first arrived in the Western Hemisphere via a land bridge that connected Siberia and Alaska about 13,000 years ago, per the Washington Post. Some argued the radiocarbon dating might've been skewed as the seeds of the aquatic plant ditchgrass could have absorbed older carbon in the water during photosynthesis.

In a new study published in Science, researchers confirm the date using other elements found in the same sediment layer as the prints, per the AP. Archaeologists gathered some 75,000 grains of pollen from coniferous trees, which radiocarbon dating revealed to be 22,600 to 23,400 years old, in line with the seed results, the Post reports. They also used a dating method known as "optically stimulated luminescence" to measure the accumulation of energy stored in crystals of quartz, which revealed them to be 21,500 years old, plus or minus 2,000 years. "It's more or less a master class in how you do this," University of Arizona archaeologist Edward Jolie tells the Post. "As Carl Sagan said, 'Extraordinary claims require extraordinary evidence.' They have some extraordinary evidence."

The dating comes as no surprise to Indigenous people, who claim their ancestors occupied the continent for tens or perhaps hundreds of thousands of years. In a 2022 book, Indigenous archaeologist Paulette FC Steeves makes the case that humans have been in the Western Hemisphere for more than 60,000 years and likely more than 100,000 years. She cites various evidence including lithic flakes found in Calico, California. Cast off in the making of stone stools, they're estimated to be 50,000 to 80,000 years old, per Canadian Geographic. Still, some scientists remain unconvinced by more and more and more evidence challenging their long-held assumptions. As Steeves tells the Post, "there is still a lot of racism and bias in American archaeology." (More archaeology stories.)