Archaeologists have found butchered bones from a mother mammoth and her calf and signs of controlled fire at the Hartley locality, an open-air site on the Colorado Plateau in northern New Mexico, the United States.
Recognizing early human occupation sites in the Americas traditionally rests on discovery of elaborately worked stone tools.
The origins of this technology trace back to the ‘Upper Paleolithic revolution’ in Europe approximately 45,000 years ago.
Elaborate, stylized stone tools then spread from Europe into central Asia and Siberia and were later introduced into the Americas by ancestors of Native Americans about 16,000 years ago.
The oldest evidence of Upper Paleolithic stone technology in the Americas is generally equated with arrival of the first humans.
However, genomic evidence for two founding populations raises the possibility of two separate human dispersals, the first preceding arrival of Native Americans by millennia.
If true, the first arrival of humans was an event entirely separate from the introduction of Upper Paleolithic technology into the Americas.
“The Clovis culture, which dates to 16,000 years ago, left behind elaborate stone-wrought tools,” said retired Texas State University Professor Mike Collins, who was not involved in the study.
“But at older sites where stone tools are absent, the evidence gets more subjective.”
The Hartley site in New Mexico includes mammoth fossils with blunt-force fractures and bone flake knives with worn edges.
And thanks to carbon dating analysis on collagen extracted from the bones, it also comes with a settled age of 36,250 to 38,900 years old, making it among the oldest known sites left behind by ancient humans in North America.
“What we’ve got is amazing,” said Professor Timothy Rowe, a paleontologist in the Jackson School of Geosciences at the University of Texas at Austin.
“It’s not a charismatic site with a beautiful skeleton laid out on its side. It’s all busted up. But that’s what the story is.”
Among other finds, CT scans revealed bone flakes with microscopic fracture networks akin to those in freshly knapped cow bones and well-placed puncture wounds that would have helped in draining grease from ribs and vertebral bones.
“There really are only a couple efficient ways to skin a cat, so to speak. The butchering patterns are quite characteristic,” Professor Rowe said.
In addition, chemical analysis of the sediment surrounding the bones showed that particles came from a controlled (domestic) fire, not a lightning strike or wildfire.
The material also contained pulverized bone and the burned remains of small animals, mostly fish, but also birds, rodents and lizards.
“The study adds to a growing body of evidence for pre-Clovis societies in North America while providing a toolkit that can help others find evidence that may have been otherwise overlooked,” Professor Collins said.
A paper on the findings appears in the journal Frontiers in Ecology and Evolution.
Timothy B. Rowe et al. Human Occupation of the North American Colorado Plateau ∼37,000 Years Ago. Front. Ecol. Evol, published online July 7, 2022; doi: 10.3389/fevo.2022.903795