Mammoth bones and ‘ghost’ footprints fuel heated debate over early humans in North America

Mammoth bones and the “ghost” footprints of ancient people are the latest evidence for scientific debate about when the first humans reached the Americas.

Fossilized bones, in particular, could suggest that people lived in North America tens of thousands of years before the generally accepted date for the arrival of the first Native Americans of around 10,000 BC.

Researchers say radiocarbon dates of chemicals in mammoth bones, of a mother and her calf, indicate that the animals lived about 37,000 years ago in what is now New Mexico. Patterns of fractures on the bones show they were slaughtered by humans, so they must have lived there at the same time, the researchers added. But the findings are disputed by other scientists, who say the fractures may have been caused naturally.

The latest “ghost” footprints, meanwhile, were discovered a few weeks ago at an Air Force missile range in a Utah desert. Scientists believe they are around 12,000 years old, but this is only the second time such footprints have been found, and they support the discovery last year of ghost footprints in New Mexico that would have at least 21,000 years old – although this discovery, too, is disputed.

A footprint discovered at an archaeological site is marked with a pin flag on the Utah Test and Training Range on July 18, 2022. (R. Nial Bradshaw/US Air Force)

Mammoth bones from what is called the Hartley site in northern New Mexico, on rocks above a tributary of the Rio Grande, are being hailed as the most conclusive evidence yet that humans arrived in the Americas up to 50,000 years ago by walking on “earth”. bridge” between what is now Siberia and Alaska.

Researchers say they are confident from their dating and interpretation that the fractures on them were caused by repeated impacts with sharp objects during their deliberate butchering. They also say there is evidence that fire was used selectively to cook many bones.

“I think it’s rock-solid radiocarbon dating,” said paleontologist Timothy Rowe, a professor at the Jackson School of Geosciences at the University of Texas at Austin. “Skeptics will put everything under the microscope, but I think we ticked every box.”

Rowe is lead author of a mammoth bone study published last month in the journal Frontiers in Ecology and Evolution.

He said the fractures and tiny splinters of bone caused by the butchery process are also distinctive and seen at butchery sites of a similar age in Europe and Asia: “If this site were in northern Siberia, no one would blink.”

The upper rib shows a fracture due to a blunt impact;  the middle rib shows a puncture wound, probably made by a tool;  lower rib has hash marks.  (Timothy Rowe/University of Texas at Austin)

The upper rib shows a fracture due to a blunt impact; the middle rib shows a puncture wound, probably made by a tool; lower rib has hash marks. (Timothy Rowe/University of Texas at Austin)

The idea that mammoths were slaughtered by early humans is supported by other recent discoveries, including human footprints at White Sands National Park in New Mexico and what are said to be stone tools. made 33,000 years ago in a cave in northern Mexico.

But the idea and the evidence are disputed by other scientists. The dating of the White Sands footprints has been questioned, and some scientists believe the objects from Mexico are not tools at all, but naturally sharp rocks.

And they dispute that the fractures on mammoth bones could only have been made by humans; instead, they could have been caused by a landslide or other natural event.

“The fracture patterns on these mammoth bones at this site can certainly be caused by humans,” said anthropologist Andre Costopoulos, a professor at the University of Alberta in Edmonton, who published a detailed review in latest research line. “But they are not necessarily diagnostic of a human presence.”

“We don’t have clear evidence yet, because there are other possible explanations that need to be ruled out first, and they haven’t been,” he said.

The lack of distinctive stone tools at the Hartley site is also a problem. Researchers say the people who slaughtered the mammoths may not have used sophisticated stone tools, just primitive tools indistinguishable from natural bone or rock.

A mixture of ribs, broken skull bones, a molar, bone fragments and stone pebbles that belonged to mammoths have been discovered in New Mexico.  It was kept under the skull and tusks of the adult mammoth.  (Timothy Rowe/University of Texas at Austin)

A mixture of ribs, broken skull bones, a molar, bone fragments and stone pebbles that belonged to mammoths have been discovered in New Mexico. It was kept under the skull and tusks of the adult mammoth. (Timothy Rowe/University of Texas at Austin)

But other scientists say there is no evidence for this, and that even primitive humans at this time could expect to have better tools.

Archaeologist Ben Potter, a professor at the University of Alaska Fairbanks, said there is evidence in Africa, Europe and the Far East that Homo sapiens used intricate stone tools from about 47,000 years ago, and so their absence from the Hartley site is significant.

He said in an email that he was unconvinced by the latest research on mammoth bones and the idea that it shows people arrived in the Americas so long ago. “Anything is possible. However, we just need to have evidence to back up that claim,” he said. “I don’t think they have enough evidence yet, and certainly not on this site.”

Some other scientists are more convinced, however, and suggest that others may be reluctant to face the possibility that some humans arrived in the Americas 50,000 years ago.

“The research seems very thorough,” said Spencer Lucas, curator of paleontology at the New Mexico Museum of Natural History and Science. “When will the archaeological community wake up and smell like coffee? There is so much evidence,” he said.

“I’m not saying this is the last piece of evidence…but you have the prints from White Sands, and the [Mexico] site – there’s all sorts of evidence piling up that points to human occupation of the New World before 20,000 years ago, and I don’t understand why this idea is still worth debating.

CORRECTION (August 4, 2022, 6:34 PM ET): A previous version of this article misrepresented Ben Potter’s employment at the University of Alaska Fairbanks. He is currently a teacher there, not previously.

Leave a Comment