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A 37,000-year-old mammoth slaughterhouse discovered in New Mexico may be the earliest evidence of humans in North America, controversial research has found. According to the new study, some of the bones at the site show signs of being processed or even used as tools by humans, “some of the strongest evidence yet,” but humans settled in North America much earlier than experts previously thought .
If the team is correct about human activity at the site, it would almost double as long as humans occupy North America. However, determining the exact date when people first appeared in North America has been a controversial topic over the past few decades, and similar studies have been dismissed as inconclusive. Some experts are equally skeptical of the team’s conclusions from the mammoth remains.
The new site was discovered on the Colorado Plateau in northern New Mexico after hiker Gary Hartley discovered a large chunk of ivory protruding from the surface. The researchers named the site “Home of the Hartley Mammoth” in his honor.
Excavations at the Hartley site have uncovered the remains of two mammoths believed to be adult females and juveniles. Most of the bones are piled up in huge piles, on which the skulls of adult women lie.go through carbon dating collagen In the skeleton, researchers estimate the remains date from 36,250 to 38,900 years ago.
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Some of the bones appear to have been made into makeshift knives, possibly used to slaughter mammoths, the researchers said. Other bones showed signs of being broken by blunt force trauma, possibly due to the use of stones, which were also found in the bone pile. Some mammoths also had thorns on their ribs, possibly caused by humans trying to collect valuable nutrients from them.
The tiny particles found in the sediment around the bones also included what the researchers suspect is crystallized ash from the fire, which may have been used to cook mammoth meat and other small animals.
“What we have is amazing,” said lead study author Timothy Rowe, a paleontologist at the University of Texas at Austin. said in a statement (opens in new tab).
When did the first Americans arrive?
Until the early 2000s, archaeological evidence suggested that the Clovis people—a group of early humans identifiable by uniquely shaped weapons—were the first humans in North America, arriving about 13,000 years ago.Another point recent discoveries It has been revealed that prior to the arrival of the Clovis people, there may have been a genetically isolated group of humans, known as the Pre-Clovis people, living in North America.
Pre-Clovis people have now been identified as the first humans to live in North America, and they can be reliably dated to about 16,000 years ago, says Justin Tackney, an anthropologist at the University of Kansas who specializes in human settlements. ) people in the Americas were not involved in the study, told Live Science in an email.
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This time frame suggests that people before Clovis arrived in North America after the end of the Last Glacial Maximum (LGM)—the most recent period of the greatest ice sheet coverage on Earth between 26,500 and 20,000 years ago. The melting ice sheet may have provided the pre-Clovis people with the opportunity to cross the Bering Land Bridge, a land that once connected North America and Asia.
However, some recent controversial research claims that pre-Clovis people may date back much earlier, possibly before the LGM. But for most experts, the idea is “a bigger pill” because the evidence from these studies is inconclusive, Tackney said.
A 2017 study investigating a similar pile of mammoth bones at a site near San Diego suggests the bones may have been processed by humans and may Dating back to about 130,000 years ago, suggesting that humans may live more than 10 times longer than previously thought. However, critics argue that the unusual orientation and “wear and tear” of these bones can also be explained by natural processes, rather than being definitely caused by humans.
related: DNA shows woolly mammoths lived on North America until 5,000 years ago
In 2020, another group of researchers claimed to have found unusually shaped rocks in Mexican caves that may have been used as stone tools and Dating back to about 30,000 years ago. but another study (opens in new tab)published in 2021, casts serious doubts about whether the rocks’ shapes suggest they are man-made.
These types of studies can be problematic because the evidence doesn’t clearly point to humans. Rather, humans are just one possible explanation. This means that researchers often create a narrative that fits with the evidence, rather than explicitly stating evidence of what really happened.
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“People in our field generally play with caution and prefer the simplest explanation,” Tackney said. “In that sense, I’m always skeptical of reporting from these sites.”
So far, the strongest evidence of Clovis settlement before the LGM comes from a 2021 study that revealed a set of 60 naked human footprints found in White Sands National Park in New Mexico.petrochemical footprint Dating back to 21,000 to 23,000 years ago Based on organic material trapped within the footprints, this suggests that pre-Clovisians may have moved into North America before or during the LGM. But the finding wasn’t enough to quell the debate.
In the new study, the researchers analyzed bones found at the Hartley site using a variety of techniques, including high-resolution CT scan and scanning electron microscopy.
These analyses showed that a small number of bones showed signs of fracture from blunt force trauma, most notably the skulls of adults. According to the study, most of the ribs showed signs of breaking from the vertebrae, and some had puncture marks, which the researchers believe may have been made by humans to extract fatty marrow from the inside of the bones. At least one rib also shows cutting marks that may have been left by humans.
“There are really only a few effective ways to skin a cat, so to speak,” Luo said. “The slaughter model is very characteristic.”
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The team also found about a dozen ossicles, which are smaller bone fragments with sharp edges that the researchers believe may have been used as knives for cutting mammoth meat. There are many more microflakes, less than 1.2 inches (3 centimeters) long, that may be by-products of when bones were turned into makeshift knives. Research has shown that not all of these flakes and microflakes can be attributed to a single bone, but there is evidence that they were sculpted perpendicular or parallel to some bones, suggesting they were not randomly generated by natural processes.
A huge boulder and several fist-sized rocks were also found in the mammoth’s bones, which researchers believe could be used to help with fractures and broken bones.
The team also found potential evidence of a controlled fire at the site. In the sediments, there were tiny crystalline ash particles, similar to those found in ancient fireplaces in past research. Chemical analysis of the particles showed that they formed in controlled fires rather than by more powerful wildfires or ancient lightning strikes. There were also bone fragments from smaller animals, and possibly even fish scales, suggesting that humans may be cooking more than just mammoths on the spot.
However, some experts remain skeptical.
“Researchers certainly have the exact date the mammoth died, but they lack definitive evidence of human activity,” said Lauriane Bourgeon, an archaeologist at the University of Kansas who specializes in the bones of ancient animals, including mammoths. “He was not involved in the study,” he told Live Science in an email. “Nor can the role of natural factors be definitively ruled out.”
Bourgeon said it’s difficult to attribute human activity to ancient bones because natural processes — such as weathering, trampling and sediment layering — can cause similar types of damage to bones.
Without clear and unambiguous tool use or human remains, Bourgeon said, it is nearly impossible to conclusively prove that the damage was caused by human activity. She added that the stones and bone fragments found inside the mammoth pile were insufficient to confirm tool use.
“I think this will remain another controversial site,” Bourgeon said.
The researchers acknowledge that some experts may be skeptical of their findings, especially when analysed in isolation, but they believe that when combined with all the evidence found at the Hartley site, a clear picture of human activity can be painted.
“It’s not a glamorous place with a beautiful skeleton next to it,” Luo said. “Everything is ruined, but that’s the story.”
The study was published online July 7 in the journal Frontiers in Ecology and Evolution (opens in new tab).
Originally published on Live Science.