Judy: When humans first populated North America, and how they arrived, has long been a matter of spirited debate. As Stephanie sy reports, a recent study dig -- detailing what archaeologists believe is the oldest known footprints in the United States is sparking new questions and upending long-held assumptions. Stephanie: Within the sprawling expanse of gypsum sand dunes in dry -- and dry lake fads in white sands national, researchers have spent years examining ancient footprints. >> You can see this. Stephanie: David Bustos says -- is them parts resource program manager. . He and a team of scientists discovered ancient animal tracks here over a decade ago. Ancient camels and mammoths, previously buried under layer of sand and clay, the sequence of footprints called a track what were revealed after a flood. Matthew Bennett is a footprint expert. >> It is probably the most important track in the Americas, both in terms of scale, geographical scale, but also in the frequency of tracks. That is what is really special about it. Stephanie: In 2017, the team confirmed they had found human footprints. >> We are brushing out a set of sloth prints. Matthew found the human print right beside the sloth print. That is what sealed the deal. Yes, you definitely have that megafauna and humans together. That is where the human side of the story began. Stephanie: The footprints show how humans coexisted with large, wild animals. Many are of children and reveal a story about everyday life and play. >> The stories of children in a puddle created by a sloth track, that is one of the most fantastic things. Children love jumping in puddles everywhere. Stephanie: One big unanswered question remained, how old the human footprints were, and whether they showed if humans inhabited North America earlier than previously thought. >> The peopling of the Americas is one of the most controversial archaeological debates, from an indigenous perspective of having always been here, from a more traditional archaeological perspective saying peopling the Americas was quite a recent event. In the controversy, one of the issues is a lack of good data points. Stephanie: That is where Jeff peck gotti, an expert in radiocarbon dating, and Kathleen springer, a geologist and paleontologist, came in. >> We need to be able to find an area where the footprints are in the lawyers of sediment, where we can find something of date the low and above so we can constrain the age of those track ways. >> You need to carve out a big trench to what aisleways say reveal the belly of the beast. And get inside. >> It is like a cross-section. >> Exactly. Then, the hope is ok, we found tracks in cross-section. Than the hope is, there better be something that is suitable for radiocarbon dating. Stephanie: It turns out there was. Layer's of seeds from aquatic grasses that grew near the track way. >> Some places, there is seeds underneath these human footprints. So we know those seeds were, and those plants were actually actively living and dying there. Stephanie: They used radiocarbon dating to determine the age of the seats. >> If we measure the amount of radiocarbon in a seed, and we know how fast it decays, we can calculate how old the plant actually is. Stephanie: Once they crunch the numbers, what they found was astounding. >> At the very bottom where people were starting to walk around, and where we have the lowest seed layer age, it is about 23,000 years old. At the top, where people were still walking around and we have the highest seed layer, is about 21,000 years old. We basically documented 2000 years of human occupation in this area at white sands and long, long time ago. Stephanie: Archaeologists have long believed humans arrived in North America 13,500 to 16,000 years ago, after a time of warming had melted massive glaciers opening up a land passage from Asia to north America. >> This is so much older. And our first reaction is, we better check everything because these better be right. Stephanie: Jeff says he has a 95% confidence level in the accuracy of the dating. >> We are as sure as you can possibly be scientifically, that that is actually the case. >> Put the evidence is not rocksolid, save some archaeologists. >> The critical issues here are, is the dating reliable? Stephanie: David Meltzer is an archaeologist at southern methodist university. He believes dating seeds from an aquatic plant to tell the age of the footprints is problematic, and says it is too early to be confident. >> The people that are doing the work, they are pros. They. Know what they are doing they know what they are about. Nature has a mischievous streak. Nature has fooled us before. The motto here is "Trust, but verify." Stephanie: Jeff peck gotti and Kathleen springer with the U.S. Geological survey expected scrutiny, and are working to carbon date pollen found in the rock layer's. Even then, there is so much yet to uncover. >> We want to expand the story to not just occupation for 2000 years between 23 and 21, but what if it looks more like this? People were here for much longer. Stephanie: If the findings hold up, it could spark a re-examination of similar dry lake bed sites in the southwest, and that could reveal even older evidence of humanity's foothold in North America. For the pbs newshour, I am Stephanie sy.
As Graham has said, history is often completely opposed to the facts.
Feet
Graham is right again!
Clovis wasn't even close to being first
The consensus ages for populating NA got pushed back to at least 30k a while ago now, video isn’t accurate