New research confirms that fossil human footprints in New Mexico are likely the oldest direct evidence of human presence in the Americas, a finding that upends what many archaeologists thought they knew about when our ancestors arrived in the New World. The footprints were discovered at the edge of an ancient lakebed in White Sands National Park and date back to between 21,000 and 23,000 years ago, according to research published Thursday in the journal Science. The estimated age of the footprints was first reported in Science in 2021, but some researchers raised concerns about the dates.