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A massive 37,000-year-old butchery site discovered in New Mexico may be the earliest evidence of humans in North America, according to controversial research. Some of the bones at the site show signs of being handled by humans or even used as tools, making it “some of the most conclusive evidence” yet that humans settled North America much earlier than experts thought before, according to the new study.
If the team is correct about human activity on the site, it would be almost double the amount of time that people spent in North America. However, determining the exact date of the first appearance of humans in North America in the past few decades is controversial, and similar studies have not been possible. Some experts are similarly skeptical about the conclusions the team has drawn from the mammoth remains.
The new site was discovered on the Colorado Plateau in northern New Mexico, after hiker Gary Hartley saw a chunk of tusk protruding from the surface. Researchers have named the site the “Hartley giant area” in his honor.
Excavation at the Hartley site revealed the incomplete remains of two mummies, believed to be an adult female and a juvenile. Most of the bones were grouped in a large pile, with the full-grown woman’s skull resting on top. With carbon dating collagen in the bones, the researchers estimated that the remains could date between 36,250 and 38,900 years ago.
Related: ‘Ghost tracks’ left by ancient hunter-gatherers discovered in Utah desert
Some of the bones appeared to be crafted into knives, possibly used to butcher the mammoths, the researchers said. Other bones showed signs of having been broken by blunt force trauma, possibly through the use of rocks, which were also found in the bone pile. There were also puncture marks in some of the mammoth’s ribs, possibly as a result of people’s attempts to gather the valuable nutrients inside.
Small particles found in the sediment around the bones included crystallized ash from what researchers believe was a fire, possibly used to cook the meat of mammals as well as other small animals.
“What we have is amazing,” lead study author Timothy Rowe, a paleontologist at the University of Texas at Austin, said in a statement (opens in a 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 distinctive weapons – were the first people in North America, arriving around 13,000 years ago. But more recent discoveries which indicated that a genetically distinct group of people, known as pre-Clovis people, probably lived in North America before the arrival of the Clovis people.
It is now firmly established that the pre-Clovis were the first people to inhabit North America, and can be reliably traced back to about 16,000 years ago, according to Justin Tackney, an anthropologist at the University of Kansas who specializes in on the human settlement. of America and was not involved in the study, Live Science said in an email.
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This time frame suggests that the pre-Clovis people arrived in North America after the end of the Last Glacial Maximum (LGM) – the most recent period when the Earth’s ice sheet coverage was at its greatest, between 26,500 and 20,000 years ago. The melting ice sheets probably allowed the pre-Clovis to cross the Bering Land Bridge, a piece of land that once connected North America and Asia.
However, some recent controversial studies have claimed that the pre-Clovis people may have been further back, possibly before the LGM. But this idea is a “much bigger hole to swallow” for most experts because the evidence from these studies is inconclusive, Tackney said.
A 2017 study investigating a similar pile of mammal bones at a site near San Diego showed that the bones may have been handled by humans dating back to around 130,000 years ago, suggesting that humans may be around 10 times longer than previously believed. However, critics argued that the unusual orientation of the bones and “wear and tear” could also be explained by natural processes and were not definitively caused by humans.
Related: Woolly mammoths lived on the North American mainland until 5,000 years ago, DNA reveals
In 2020, another group of researchers claimed to have found unusual rocks in a Mexican cave that may have been used as stone tools and date to around 30,000 years ago. But another study (opens in a new tab)published in 2021, there was serious doubt as to whether the shape of the rocks indicated that they were man-made.
These types of studies can be problematic because the evidence does not focus definitively on people. Instead, humans are only one possible explanation. This means that researchers are often creating a story to fit the evidence, rather than the evidence that clearly shows what actually happened.
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“People in our field tend to be on the side of caution, and the simplest explanations are best,” Tackney said. “In that sense, I’m always very skeptical of reports from sites like this.”
To date, the most definitive evidence of pre-LGM settlement for pre-Clovis people comes from a 2021 study that revealed 60 bare human footprints found at White Sands National Park in New Mexico. The fossil tracks between 21,000 and 23,000 years ago based on organic matter trapped within the footprints, suggesting that pre-Clovis humans may have moved into North America before or during the LGM. But this discovery was not enough to settle the debate.
In the new study, researchers analyzed the bones found at the Hartley site using several techniques, including high-resoln. CT scans and scanning electron microscopy.
These analyzes indicated that a handful of the bones showed signs of being broken by blunt force trauma, including, in particular, the adult’s skull. Most of the ribs showed signs that the vertebrae had been removed and some had puncture marks that the researchers believe may have been made by humans to remove fatty marrow from inside the bone, according to the study. At least one rib shows cut marks similar to marks that might have been left by humans.
“There are really only a few effective ways to skin a cat, so to speak,” Rowe said. “The butchering patterns are quite characteristic.”
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The team also identified about a dozen bone flakes, smaller fragments of bone with sharp edges, which the researchers think could have been used as knives to cut the mammal’s flesh. There were also many more microflakes, less than 1.2 inches (3 centimeters) long, which could have been created as a by-product when the bones were turned into knives. Not all of these flakes and microflakes can be attributed to individual bones, but there is evidence that they were carved perpendicular or parallel to some of the bones, suggesting that they were not created randomly by natural processes, according to the study.
Large boulders and some fist-sized rocks were also found among the giant bones, which the researchers think could have been used to aid in the breaking and breaking of the bones.
The team also found evidence of a controlled fire at the scene. The sediment contained tiny particles of crystallized ash, similar to those found inside ancient hearths from past studies. Chemical analysis of the particles suggests they were formed in a controlled fire and not by a much more powerful wildfire or an ancient lightning strike. There were bone fragments from smaller animals and possibly even fish scales, suggesting that people may have cooked more than one mammal at the site.
However, some experts are skeptical.
“The researchers definitely have a firm date for the death of the mummies, but they don’t have definitive evidence of human activity,” Lauriane Bourgeon, an archaeologist at the University of Kansas who specializes in the bones of ancient animals, including mammals, and did not associated with. the study, told Live Science in an email. “The role of natural factors cannot be definitively ruled out either.”
It can be very difficult to attribute human activity to ancient bones because natural processes — such as weathering, trampling and sediment layering — can cause similar damage to the bones, Bourgeon said.
Without clear and unambiguous tool use or human remains, it is nearly impossible to prove conclusively that the damage was caused by human activity, Bourgeon said. The stones found inside the mammoth pile and the bone flakes are not enough to confirm tool use, she said.
“I think this is going to be another controversial site,” Bourgeon said.
The researchers admitted that some experts may be skeptical of their findings, especially when analyzed individually, but they believe that all the evidence found at the Hartley site together provides a clear picture of human activity.
“It’s not a charismatic site with a beautiful skeleton laid out on its side,” Rowe said. “It’s all busted up, but that’s the story.”
The study was published online July 7 in the journal Frontiers in Ecology and Evolution (opens in a new tab).
It was originally published on Live Science.