This undated photo made available by the National Park Service in September 2021 shows fossilized human fossilized footprints at the White Sands National Park in New Mexico. According to a report published in the journal Science on Thursday, Sept. 23, 2021, the impressions indicate that early humans were walking across North America around 23,000 years ago, much earlier than scientists previously thought. (NPS via AP)

September 23, 2021