Footprints Show Humans in the Americas over 20,000 Years Ago
The Enduring Story of Human Wanderlust
A recently calculated time frame for a series of ancient human footprints at White Sands National Park, New Mexico, is bringing people, especially anthropologists and archeologists, to their feet.
These footprints were discovered in 2009 by park staff; turns out there are thousands of preserved human other animal footprints — mammoth and giant sloths, for example — all over White Sands. But The United States Geological Survey has just completed working out the age of human prints, and their date of 23,000 years old significantly changes our understanding the great human migration into the Americas.
Long ago in graduate school, I was taught that people arrived here about 12,000 years ago by walking across the Bering Strait, the water gap between Siberia and Alaska. According to that story, people had moved out of Africa over many millennia and eventually found themselves in Europe, Russia, Australia, the Near and the Far East, and up into Siberia. And then, presumably following herds of large game, some ventured across the Bering Strait when the water level was low and there was a contiguous land bridge between the continents. This bridge apparently appeared several times over the last 10,000 years as water s rose and fell, letting immigrants pass into a new environment in waves, even if they didn’t know they were walking from one continent to another.
This hypothesis was the norm because it had been supported by stone tools dated about 13,000 years ago found near Clovis, New Mexico. And so, every year, for decades, I repeated that scenario in my introductory biological anthropology courses and showed the class a charming illustration of a group of weary unkempt people trudging across the Being Strait with spears and determined faces.
But I knew that such scenarios can always change, as they often do when paleontologists and archaeologists unearth new discoveries. Eventually, there was another camp of scholars who felt the date of human migration into the Americas must have happened much earlier, and they also had evidence. Over the years, archaeologists have found stone tools, animal remains, chewed up wads of seaweed, and burned areas that suggest human-made fire dated 18,000 years ago at a site called Monte Verde in Chile, which is at the tip of South America and very far from the Bering Strait. Other finds pushed the date back even further. For example, there is now a group of stone tools from a Brazilian cave dated 22,000 years ago, and layers of purposefully burnt wood below those tools. A pile of animal bones that might have been dinner has also been excavated in a Mexican cave dated about 30,000 years ago and those bones, too, are associated with stone tools.
But dates of some of these older finds have been disputed in the way that academic archaeologists love to argue — “Those stones could just be tumbled rock!” “The animal bones could have been put there by wolves!” “Your dating methods suck!” And so, the history of humans coming to the Americas has lately been in flux.
Interwoven within all the technical chat about dates and artifacts is the social question of how and why humans made such a long trek from Siberia to Chile and what path they took. The first story I heard was that our ancestors crossed the Strait and then hugged the Pacific Coast walking down into South America. Years later, a teaching assistant of mine who was an archeologist corrected that story to add the possibility that the various waves of incoming humans from the Strait might have fanned out across North America and opportunistically headed south through various verdant corridors revealed by melting glaciers. Most recently, there has been another proposal that humans came across the Pacific in boats from East Asia and landed all along the West coast of the Americas. And yet, in all these travel venues, the timeline has always seemed too short for nomadic hunter and gathering peoples to make it so far across both North and South America and all the way down to the southernmost tip of Chile.
That’s why a solid and much older date for entry into the Americas makes sense, and why human footprints in New Mexico 23,000 years ago are an intriguing piece of this historical puzzle. The geologists used a standard dating technique of comparing known dates of flora or fauna to evaluate another similar geological layer containing evidence such as footprints that can’t, in themselves, be directly dated. They compared the presence of preserved ditch grass seed pods and their known dates to the layers of the footprints and to their shock, which means the footprints were 23,000 years old. Apparently, adults and children were prancing around White Sands in the Western part of the United States, probably hunting and eating the other animals, long before whoever might have come across the Bering Strait 15,000 or so years ago.
These old footprints are also significant because they speak to the apparently innate tendency of humans to be on the move. After our ancestors stood up on two legs about 6 million years ago, they set off across the savannahs and forests of Africa and headed northeast and out of that continent, and no one knows why. Other animals migrate for various reasons — food, safe mating grounds, familiar sites to have babies — but humans seem to have a more elusive, and compelling, urge to go somewhere else, taking geographical complexity in stride. Like other migrating animals, our ancestors might have been following food on the hoof or leaving places of drought and withering vegetation, but really, how hard would have been thousands or millions of years ago to find food when the forests and seas were more full of game and plants than they are now? If not food, then maybe we have always been a species that runs away from trouble and all this early migration was simply about moving from a bad place to a better place, like much of emigration today.
No matter the impetus, humans have walked all over the world, never daunted by mountain ridges, deserts, or bodies of water, and that’s quite an accomplishment for one species. But in that glorious global trek, we highly mobile humans have also concluded that we own the earth and all its resources, and that has turned into a curse. In the end, our ancient wanderlust might just be our downfall.
