(CNN) — The startling discovery of giant fossils in a paleontologist’s backyard has led to an even more unexpected discovery.
The remains of a female mammoth and her calf, some 37,000 years old, show clear signs of carnage, providing new evidence that humans may have arrived in North America much earlier than previously thought.
Paleontologist Timothy Rowe became aware of the fossils in 2013, when a neighbor noticed something sticking out of a hillside owned by Rowe, a New Mexico property.
Upon closer inspection, Rowe found a tooth, a sunken giant skull and other bones that appeared to be intentionally broken. I thought this was the place where the two mammoths were bitten.
“What we have here is amazing,” Rowe said in a statement. “It’s not a charismatic site with a beautiful skeleton lying on its side. It’s all broken. But that’s the story.”
Rowe, a professor in the Jackson School of Geosciences at the University of Texas at Austin, specializes in vertebrate paleontology and does not typically study mammoths or early humans. But he could not help working on the investigation because of the location of the find.
Rowe said two six-week excavations were carried out at the site in 2015 and 2016, but laboratory analysis has taken and is ongoing. Rowe is the lead author of a new study offering an analysis of the site and its implications, published in July in the academic journal Frontiers in Ecology and Evolution.
“I have yet to fully process the cosmic coincidence I see in my backyard,” Rowe wrote in an email.
Several finds of the site paint a picture of what happened there thousands of years ago, including bone tools, evidence of fire, broken bones and other signs of human butchering of animals.
Disposable knife-shaped long mammoth bones were used to break up animal carcasses before a fire helped melt their fat.
According to the study, fractures produced by brute force have been observed in bones. There were no stone tools at the site, but researchers found a scaling knife made of bone with rough edges.
A chemical analysis of the sediments around the mammoth bones showed that the fire was sustained and controlled and was not caused by wildfires or lightning. There was also evidence of pulverized bones and burnt remains of small animals, including birds, fish, rodents and lizards.
The research team used CT scans to analyze the bones at the site to detect puncture wounds that would have removed fat from the ribs and vertebrae. Rowe said the humans who killed the mammoths were all over.
“I have excavated dinosaurs that were eaten by scavengers, but the pattern of disintegration and breakage of bones resulting from human carnage was unlike anything I had seen,” Rowe said.
The most surprising detail of the site is that it is located in New Mexico, and previous tests have suggested that humans were not there until thousands of years later.
tracing the first human steps
Collagen extracted from mammoth bones helped researchers determine that the animals were slaughtered at the site between 36,250 and 38,900 years ago. This age range makes the New Mexico site one of the oldest humans ever created in North America, the researchers said.
Scientists have debated for years when the first humans arrived in North America.
The 16,000-year-old Clovis culture is known for the stone tools it left behind. But a growing body of evidence suggests that the oldest sites in North America were home to pre-Clovis populations that had a distinct genetic lineage. Older sites have a different kind of evidence, such as preserved footprints, bone tools, or animal bones with cut marks dating back more than 16,000 years.
“Humans have lived in the Americas for more than twice as long as archaeologists have kept for many years,” Rowe said. “This site indicates that humans reached global distribution much earlier than previously thought.”
According to the study, the location of the site, which is within the western interior of North America, suggests that the first humans arrived 37,000 years ago. These early humans probably traveled by overland or coastal routes.
Rowe said he would like to sample the site to look for signs of further ancient DNA.
“Tim has done an outstanding and thorough job that represents cutting-edge research,” retired Texas State University professor Mike Collins said in a statement. “He is creating a path that others can learn from and follow.”
Collins was not involved in the study. He led research at the Gault Archaeological Site, which includes Clovis and pre-Clovis artifacts near Austin, Texas.
“I think the discovery of a deeper meaning of the early human achievement of global distribution is an important new question,” Rowe said. “Our new techniques have provided subtle evidence of human presence in the archaeological record, and I suspect there are other sites of comparable or even greater age that have gone unrecognized.”