Humans May Have Lived in North America Earlier Than Thought

That is a human footprint there. There's a human footprint, right? Yeah, so if you look that is amazing. Here's the hill. Okay, right here Scattered across the landscape are human footprints from thousands of years ago Each track is a trace of an ancient person The shape of their bare feet locked in the sediment, but how long ago were these people here? In order to date the prince the team has dug a trench It reveals layers of sediment deposited over many years along the shore of this ancient lake Stamped on these buried surfaces are human prints and the farther down they are the older they are But just how old are they? I can put them both on. Okay. Sure to help find the answer David has been joined by geologist Kathleen Springer and Jeff Pagotti who is also an expert in radiocarbon dating You've cut a cross-section. What are you trying to see with the cross? So the footprints themselves are just an impression on a surface There's nothing to date. It's an inorganic thing You have to find something organic that you can date above and below the footprints and get good dates on them So that you can actually say that footprint is between these two ages In this trench Kathleen and Jeff have made a crucial find Sandwiched in the layers above and below the footprints are scatterings of ancient seeds Precious organic material which the team can date That way they can establish a window of time for when the prints were made There were actually plants Growing on this on this surface when you know, these critters were walking the same layers that have the tracks will have Above and below them. Yes, so above and below them that that way we can constrain in time So in your seeds are effectively little time pieces, right? They're like little clocks little capsules Yeah, and basically the the these things are really resistant to to decay And so they look like they were put down on the on the landscape just yesterday But in fact, they might be tens and you know tens of thousands of years old at the US Geological Survey Lab Jeff has been analyzing the seeds they found in the sediment layers at White Sands He's been using radiocarbon dating to calculate the age of the seeds and from that the age of the footprints It's the moment of truth After more than a year and a half have Kathleen and Jeff managed to find out the age of the footprints So tell me What were the dates of those footprints? we were able to document that humans were in White Sands National Park between 23,000 years ago and about 21,000 years ago 23,000 years ago. That's way older than there's been good evidence for humans About 10,000 years older than sort of the established sort of thought of when humans Arrived in the Americas and you got tracks at more than one layer Which means that wasn't just one group of people at one moment in time But it was many groups of people over a lot of time 2,000 years I mean 2,000 years itself is a long it is duration. But the fact that they were here 23,000 years ago. Yeah crazy blows my mind. I mean, it's alarm I If these dates are correct that would make the White Sands footprints the earliest direct evidence of humans ever found in North America