When we are little, we learn a simplified view of just about everything that both comforts us with the idea that we actually understand the world and sweeps away all the controversies that are alive and well among researchers who don’t all agree on what different data and research actually mean. 

The story of how humans originally came to the Americas, for instance, is taught as an elegant picture where, during the last glacial age, a land bridge stretched from modern-day Siberia to modern-day Alaska, and 15,000-25,000 years ago humans crossed the Bering Sea and over thousands of years, migrated south and west to fill the continents with vibrant societies that were all but destroyed when smallpox came to the Americas with Europeans in the last half millennia. Sometimes books will mention that random boats may have made the trip from Polynesian islands or even from Western Africa to South America. 

What is generally omitted is the highly controversial evidence of human settlement in the American Southwest as early as 30,000 years ago, before the glacial period. None of the sites so far found has been a slam dunk that scholars could look at and say, “Yes, that is from humans, and yes, that is really that old.” Confusion arises in both methods for age-dating and in knowing that rocks that appear shaped into blades were actually shaped by humans and not nature.

Scientists trying to understand how life can arise on a world and how intelligent life can move on to fill a world’s ecosystems look to the Americas and their position so far from South Africa’s cradle of humanity as the final ecosystem humans would have entered. Understanding human migration gives us insight into the rise of life on planets and lets us imagine the rise of life on other planets.

White Sands, New Mexico, is a place where science, technology, and deep history all come together. This sprawling landscape of shockingly white sand is in one area a national park and in another area a missile range. This area is home to the first adaptive optics telescopes, and sites at the foot of Apache Point are the home of the National Solar Observatory and the Sloan Digital Sky Survey. It is also home to ancient footsteps from humans and mammals now extinct that are fossilized in a dry lake bed.

Dating these footprints has been a challenge because sand doesn’t exactly contain the stuff needed to carbon date or otherwise radio-date samples. To give an age to these myriad footprints of different individuals, it was necessary to find imprints that passed between layers containing vegetation – vegetation that can be carbon dated.

In a new paper in the journal Science and led by Michael Bennett, researchers describe a set of tracks, above and below layers of sediment containing seeds, which they were able to radiocarbon date to between 21,000 and 23,000 years ago. There are only two ways to explain these footprints that we know: either they actually are that old and push back the arrival of people in the American Southwest, or the seeds used for radiocarbon dating contained carbon that was absorbed from rocks dating back to 21,000 – 23,000 years ago, and it really looks like it could be that the footprints were just that old. If this is true, it indicates that life will find a way, even if it means finding a way through massive ice sheets or across great oceans to find new places to settle.

I am hoping that this research will trigger a meeting of researchers who will come together to once again look at sites like Mesa Verde, Gault, and Clovis, and to work – as these researchers worked – with the elders of the tribes that have lived on these lands since those original settlers arrived. From story and archeology, we may get at the truth of humanity’s sprawl across planet Earth.

More Information

The University of Arizona press release

Fossilized footprints show humans made it to North America much earlier than first thought (CNN)

“Evidence of humans in North America during the Last Glacial Maximum,” Matthew R. Bennett et al., 2021 September 24, Science