“Homo sapiens” was already on the american continent before the end of the last ice age.
Footprints dating back some 23,000 years have been discovered in the White Sands, New Mexico. A study revealed on Thursday 23 September suggests that human settlement of North America was already underway long before the end of the last Ice Age, which is thought to have enabled this migration. The footprints were left in the mud on the shores of a now-dry lake that has given way to a white gypsum desert in New Mexico’s White Sands National Park.
Over time, the sediments filled in the footprints and hardened, protecting them until erosion reopened the evidence of the past, much to the delight of scientists. “Many of the tracks appear to be those of adolescents and children; large adult footprints are less common,” write the authors of the study published in the American journal Science. Animal tracks, mammoths and prehistoric wolves were also identified. Some, such as those of giant sloths, are even contemporary and close to human footprints on the shores of the lake.
Beyond the emotion and the anecdote, the discovery is decisive for the debate raging about the origins of the arrival of Homo sapiens in America, the last continent populated by our species. For the dating of the White Sands tracks “means that humans were present in the landscape at least 23,000 years ago, with evidence of occupation spanning approximately two millennia,” the study says.
Bering Strait theory challenged
For decades, the most commonly accepted theory has been that settlement originated in eastern Siberia : our ancestors crossed a land bridge - the present-day Bering Strait - to land in Alaska and then spread further south. Archaeological evidence, including spearheads used to kill mammoths, has long suggested a 13,500-year-old settlement associated with a so-called "Clovis culture" - named after a town in New Mexico - considered the first American culture, from which the ancestors of the American Indian originated.
This "early Clovis culture" model has been challenged over the past twenty years, with new discoveries that have pushed back the age of the first settlements. But generally, this date was no more than 16,000 years after the end of the "last glacial maximum". This episode of glaciation is crucial, because it is commonly accepted that the ice caps covering most of the northern part of the continent at the time made human migration from Asia, through the Bering Strait or, as recent discoveries suggest, along the Pacific coast, impossible or at least very difficult.
“From my point of view, of all the data published to date on the first settlement of America, this site is the most convincing for pre-20,000 year-old sites,” says Yan Axel Gomez Coutouly, a researcher at the American Archaeology joint research and training unit (CNRS, Paris-I Panthéon-Sorbonne) . And this is true even if there is no lithic material or associated tools, since the footprints confirm the human origin.
“For most of the ancient sites - Chiquihuite Cave in Mexico dated at 30 000 years, Pedra Furada rock shelter in Brazil dated at up to 50 000 years, Bluefish Caves in the Yukon with dates up to 24 000 years, Cerutti Mastodon site in California with dates up to 120 000 years -, reminds the archaeologist, a large majority of researchers consider that the evidence of human presence presented (traces of cutting, simple tools, fireplaces, etc... are in fact the product of phenomena such as the presence of a large number of people in the area) are in fact the product of natural phenomena : rather than artefacts (human products), they are geofacts (natural products).”
In the case of these footprints of about 22,000 years, he adds, “the study shows a discovery that is unquestionably anthropogenic. So if these dates are confirmed and not questioned, this will be one of the major discoveries in American prehistory in recent decades.”
