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Yahoo
14 hours ago
- Science
- Yahoo
Evidence is building that people were in the Americas 23,000 years ago
When you buy through links on our articles, Future and its syndication partners may earn a commission. The age of "rarely preserved" ancient human footprints dotting the landscape at White Sands National Park in New Mexico has been hotly debated for years. Now, a new study has found that these footprints really are around 23,000 years old — but the date isn't accepted by everyone. If the 23,000-year-old age is accurate, it would mean that humans were in North America around the peak of the Last Glacial Maximum, the coldest part of the last ice age — far earlier than archaeologists had previously thought. In the new study, the researchers radiocarbon-dated organic sediment in core samples from the site, which provided dates for the footprints as well as for the entire paleolake and river system that once existed there. The analysis was done in labs unaffiliated with earlier studies. "Our data supports the original data" that dated the site to 23,000 years ago, study first author Vance Holliday, a professor emeritus of anthropology and geosciences at the University of Arizona, told Live Science. "Plus, we now have an idea of what the landscape was like when people were out there." The saga of dating the roughly 60 footprints goes back to 2021, when a study reported the discovery of the footprints and dated them to between 21,000 and 23,000 years old. However, a 2022 rebuttal took issue with using the seeds of ditch grass (Ruppia cirrhosa), a water plant, for radiocarbon dating. Water plants get their carbon from underwater, which can be much older than carbon from the atmosphere. This can skew the levels of carbon 14, a radioactive version of the atom, in the samples, making the plants appear older than they really are. So, in 2023, researchers redated the site with optically stimulated luminescence (OSL) dating, which revealed when quartz or feldspar grains in the tracks were last exposed to sunlight, and radiocarbon dating of ancient conifer pollen from the footprint layer — which proved to be another way to use carbon 14 without relying on water plants. Related: The 1st Americans were not who we thought they were Again, the scientists found that the footprints were 21,000 to 23,000 years old. While some scientists called the results "very convincing," others, including those who wrote the 2022 rebuttal, were still wary of the results, saying the samples weren't taken from the right layer. Now, the new study offers more evidence that the footprints date to the Last Glacial Maximum, when the area was a vast wetland inhabited by ice age animals. The footprints likely came from hunter-gatherers who arrived in the Americas after traveling along the Bering Land Bridge, which connected Siberia and Alaska when sea levels were lower, research suggests. For decades, researchers thought the earliest Americans were the Clovis, who lived in North America around 13,000 years ago. But the footprint discovery and others are slowly revealing that Indigenous people reached the Americas much earlier than thought. Holliday has been working at White Sands since 2012, and some of his data was used in the original 2021 study, making him a co-author, he noted. This time, Holliday and his colleagues radiocarbon-dated mud cores from the site. They found that the trackways date to between 20,700 and 22,400 years ago, which closely matches the original dates. When added together, there are now a total of 55 radiocarbon-dated samples of mud, seeds and pollen from the footprint layer that support the 21,000- to 23,000-year-old dates, Holliday said. Ancient human footprints are "so rarely preserved," he said. And now, scientists have "dates on three different materials that all coincide" on a time for these tracks. "You get to the point where it's really hard to explain all this away," he said in a statement. "As I say in the paper, it would be serendipity in the extreme to have all these dates giving you a consistent picture that's in error." However, more work is needed to securely date the footprints at White Sands, said Michael Waters, director of the Center for the Study of the First Americans at Texas A&M University, who was not involved with the study. "Even with these new data, I remain concerned about the radiocarbon ages generated to date the footprints at White Sands," Waters told Live Science in an email. He reiterated the known Ruppia issue, saying the radiocarbon dates "are likely too old" because the plant got its carbon from the water. In fact, the same underwater carbon issues could have also affected the sediments dated in the new study, he said. "The new ages on bulk organic sediments presented in this paper are interesting, but it is unclear about the origin of the carbon being dated," Waters said. RELATED STORIES —13 of the oldest archaeological sites in the Americas —Ice age children frolicked in 'giant sloth puddles' 11,000 years ago, footprints reveal —How did humans first reach the Americas? Furthermore, Holliday and his colleagues acknowledge that their study doesn't address another hot-button issue: Where are the artifacts or settlements from these ice age people at White Sands? That question remains to be answered, Holliday said. But it's unlikely that hunter-gatherers would have left behind valuable items in the short time it took them to trek around the wetland. "These people live by their artifacts, and they were far away from where they can get replacement material," Holliday said in the statement. "They're not just randomly dropping artifacts. It's not logical to me that you're going to see a debris field."
Yahoo
18 hours ago
- Science
- Yahoo
New research strengthens case for age of ancient New Mexico footprints
By Will Dunham (Reuters) -A new line of evidence is providing further corroboration of the antiquity of fossilized footprints discovered at White Sands National Park in New Mexico that rewrite the history of humans in the Americas. Researchers used a technique called radiocarbon dating to determine that organic matter in the remains of wetland muds and shallow lake sediments near the fossilized foot impressions is between 20,700 and 22,400 years old. That closely correlates to previous findings, based on the age of pollen and seeds at the site, that the tracks are between 21,000 and 23,000 years old. The footprints, whose discovery was announced in 2021, indicate that humans trod the landscape of North America thousands of years earlier than previously thought, during the most inhospitable conditions of the last Ice Age, a time called the last glacial maximum. The age of the footprints has been a contentious issue. Asked how the new findings align with the previous ones, University of Arizona archaeologist and geologist Vance Holliday, the study leader, replied: "Spectacularly well." Homo sapiens arose in Africa roughly 300,000 years ago and later spread worldwide. Scientists believe our species entered North America from Asia by trekking across a land bridge that once connected Siberia to Alaska. Previous archaeological evidence had suggested that human occupation of North America started roughly 16,000 years ago. The hunter-gatherers who left the tracks were traversing the floodplain of a river that flowed into an ancient body of water called Lake Otero. The mud through which they walked included bits of semi-aquatic plants that had grown in these wetlands. Radiocarbon dating is used to determine the age of organic material based on the decay of an isotope called carbon-14, a variant of the element carbon. Living organisms absorb carbon-14 into their tissue. After an organism dies, this isotope changes into other atoms over time, providing a metric for determining age. "Three separate carbon sources - pollen, seeds and organic muds and sediments - have now been dated by different radiocarbon labs over the course of the trackway research, and they all indicate a last glacial maximum age for the footprints," said Jason Windingstad, a University of Arizona doctoral candidate in environmental science and co-author of the study published this week in the journal Science Advances. The original 2021 study dated the footprints using radiocarbon dating on seeds of an aquatic plant called spiral ditchgrass found alongside the tracks. A study published in 2023 used radiocarbon dating on conifer pollen grains from the same sediment layers as the ditchgrass seeds. But some scientists had viewed the seeds and pollen as unreliable markers for dating the tracks. The new study provides further corroboration of the dating while also giving a better understanding of the local landscape at the time. "When the original paper appeared, at the time we didn't know enough about the ancient landscape because it was either buried under the White Sands dune field or was destroyed when ancient Lake Otero, which had a lot of gypsum, dried out after the last Ice Age and was eroded by the wind to create the dunes," Holliday said. Today, the landscape situated just west of the city of Alamogordo consists of rolling beige-colored dunes of the mineral gypsum. "The area of and around the tracks included water that came off the mountains to the east, the edge of the old lake and wetlands along the margins of the lake. Our dating shows that this environment persisted before, during and after the time that people left their tracks," Holliday said. The area could have provided important resources for hunter-gatherers. "We know from the abundant tracks in the area that at least mammoths, giant ground sloths, camels and dire wolves were around, and likely other large animals. Given the setting, there must have been a large variety of other animals and also plants," Holliday added. The climate was markedly different than today, with cooler summers and the area receiving significantly more precipitation. "It is important to note that this is a trackway site, not a habitation site," Windingstad said. "It provides us a narrow view of people traveling across the landscape. Where they were going and where they came from is obviously an open question and one that requires the discovery and excavation of sites that are of similar age in the region. So far, these have not been found."
Reuters
a day ago
- Science
- Reuters
New research strengthens case for age of ancient New Mexico footprints
June 19 (Reuters) - A new line of evidence is providing further corroboration of the antiquity of fossilized footprints discovered at White Sands National Park in New Mexico that rewrite the history of humans in the Americas. Researchers used a technique called radiocarbon dating to determine that organic matter in the remains of wetland muds and shallow lake sediments near the fossilized foot impressions is between 20,700 and 22,400 years old. That closely correlates to previous findings, based on the age of pollen and seeds at the site, that the tracks are between 21,000 and 23,000 years old. The footprints, whose discovery was announced in 2021, indicate that humans trod the landscape of North America thousands of years earlier than previously thought, during the most inhospitable conditions of the last Ice Age, a time called the last glacial maximum. The age of the footprints has been a contentious issue. Asked how the new findings align with the previous ones, University of Arizona archaeologist and geologist Vance Holliday, the study leader, replied: "Spectacularly well." Homo sapiens arose in Africa roughly 300,000 years ago and later spread worldwide. Scientists believe our species entered North America from Asia by trekking across a land bridge that once connected Siberia to Alaska. Previous archaeological evidence had suggested that human occupation of North America started roughly 16,000 years ago. The hunter-gatherers who left the tracks were traversing the floodplain of a river that flowed into an ancient body of water called Lake Otero. The mud through which they walked included bits of semi-aquatic plants that had grown in these wetlands. Radiocarbon dating is used to determine the age of organic material based on the decay of an isotope called carbon-14, a variant of the element carbon. Living organisms absorb carbon-14 into their tissue. After an organism dies, this isotope changes into other atoms over time, providing a metric for determining age. "Three separate carbon sources - pollen, seeds and organic muds and sediments - have now been dated by different radiocarbon labs over the course of the trackway research, and they all indicate a last glacial maximum age for the footprints," said Jason Windingstad, a University of Arizona doctoral candidate in environmental science and co-author of the study published this week in the journal Science Advances, opens new tab. The original 2021 study dated the footprints using radiocarbon dating on seeds of an aquatic plant called spiral ditchgrass found alongside the tracks. A study published in 2023 used radiocarbon dating on conifer pollen grains from the same sediment layers as the ditchgrass seeds. But some scientists had viewed the seeds and pollen as unreliable markers for dating the tracks. The new study provides further corroboration of the dating while also giving a better understanding of the local landscape at the time. "When the original paper appeared, at the time we didn't know enough about the ancient landscape because it was either buried under the White Sands dune field or was destroyed when ancient Lake Otero, which had a lot of gypsum, dried out after the last Ice Age and was eroded by the wind to create the dunes," Holliday said. Today, the landscape situated just west of the city of Alamogordo consists of rolling beige-colored dunes of the mineral gypsum. "The area of and around the tracks included water that came off the mountains to the east, the edge of the old lake and wetlands along the margins of the lake. Our dating shows that this environment persisted before, during and after the time that people left their tracks," Holliday said. The area could have provided important resources for hunter-gatherers. "We know from the abundant tracks in the area that at least mammoths, giant ground sloths, camels and dire wolves were around, and likely other large animals. Given the setting, there must have been a large variety of other animals and also plants," Holliday added. The climate was markedly different than today, with cooler summers and the area receiving significantly more precipitation. "It is important to note that this is a trackway site, not a habitation site," Windingstad said. "It provides us a narrow view of people traveling across the landscape. Where they were going and where they came from is obviously an open question and one that requires the discovery and excavation of sites that are of similar age in the region. So far, these have not been found."
CNA
a day ago
- Science
- CNA
New research strengthens case for age of ancient New Mexico footprints
A new line of evidence is providing further corroboration of the antiquity of fossilized footprints discovered at White Sands National Park in New Mexico that rewrite the history of humans in the Americas. Researchers used a technique called radiocarbon dating to determine that organic matter in the remains of wetland muds and shallow lake sediments near the fossilized foot impressions is between 20,700 and 22,400 years old. That closely correlates to previous findings, based on the age of pollen and seeds at the site, that the tracks are between 21,000 and 23,000 years old. The footprints, whose discovery was announced in 2021, indicate that humans trod the landscape of North America thousands of years earlier than previously thought, during the most inhospitable conditions of the last Ice Age, a time called the last glacial maximum. The age of the footprints has been a contentious issue. Asked how the new findings align with the previous ones, University of Arizona archaeologist and geologist Vance Holliday, the study leader, replied: "Spectacularly well." Homo sapiens arose in Africa roughly 300,000 years ago and later spread worldwide. Scientists believe our species entered North America from Asia by trekking across a land bridge that once connected Siberia to Alaska. Previous archaeological evidence had suggested that human occupation of North America started roughly 16,000 years ago. The hunter-gatherers who left the tracks were traversing the floodplain of a river that flowed into an ancient body of water called Lake Otero. The mud through which they walked included bits of semi-aquatic plants that had grown in these wetlands. Radiocarbon dating is used to determine the age of organic material based on the decay of an isotope called carbon-14, a variant of the element carbon. Living organisms absorb carbon-14 into their tissue. After an organism dies, this isotope changes into other atoms over time, providing a metric for determining age. "Three separate carbon sources - pollen, seeds and organic muds and sediments - have now been dated by different radiocarbon labs over the course of the trackway research, and they all indicate a last glacial maximum age for the footprints," said Jason Windingstad, a University of Arizona doctoral candidate in environmental science and co-author of the study published this week in the journal Science Advances. The original 2021 study dated the footprints using radiocarbon dating on seeds of an aquatic plant called spiral ditchgrass found alongside the tracks. A study published in 2023 used radiocarbon dating on conifer pollen grains from the same sediment layers as the ditchgrass seeds. But some scientists had viewed the seeds and pollen as unreliable markers for dating the tracks. The new study provides further corroboration of the dating while also giving a better understanding of the local landscape at the time. "When the original paper appeared, at the time we didn't know enough about the ancient landscape because it was either buried under the White Sands dune field or was destroyed when ancient Lake Otero, which had a lot of gypsum, dried out after the last Ice Age and was eroded by the wind to create the dunes," Holliday said. Today, the landscape situated just west of the city of Alamogordo consists of rolling beige-colored dunes of the mineral gypsum. "The area of and around the tracks included water that came off the mountains to the east, the edge of the old lake and wetlands along the margins of the lake. Our dating shows that this environment persisted before, during and after the time that people left their tracks," Holliday said. The area could have provided important resources for hunter-gatherers. "We know from the abundant tracks in the area that at least mammoths, giant ground sloths, camels and dire wolves were around, and likely other large animals. Given the setting, there must have been a large variety of other animals and also plants," Holliday added. The climate was markedly different than today, with cooler summers and the area receiving significantly more precipitation. "It is important to note that this is a trackway site, not a habitation site," Windingstad said. "It provides us a narrow view of people traveling across the landscape. Where they were going and where they came from is obviously an open question and one that requires the discovery and excavation of sites that are of similar age in the region. So far, these have not been found."
Forbes
2 days ago
- Health
- Forbes
University Of Arizona To Offer A Three-Year MD Program
The University of Arizona is joining the ranks of institutions offering an accelerated three-year ... More medical degree. The University of Arizona has become the latest institution in the nation to offer a three-year medical degree. The program, approved this month by the Arizona Board of Regents, is intended to address the shortage of primary care physicians in the state, particularly in its rural communities. The new three-year medical degree program will be offered at both of the university's separately accredited medical schools in Tucson and Phoenix. 'We appreciate the Arizona Board of Regents' approval of this new medical degree pathway, which will allow us to leverage the strength of the University of Arizona's two medical schools to improve access to health care for all Arizonans,' said University of Arizona Provost Patricia Prelock, in a news release. 'We are committed to reducing the state's primary care physician shortage, and these new programs will allow us to move expeditiously to improve the well-being of all Arizona residents.' More than 30 universities in the U.S. offer a three-year medical degree program. Most of them are members of the Consortium of Accelerated Medical Pathway Programs (CAMPP), an organization of medical schools in the United States and Canada that was formed in 2015 by an original consortium of eight institutions: New York University School of Medicine, McMaster University, Texas Tech University Health Sciences Center School of Medicine, Mercer University School of Medicine, University of California Davis, Medical College of Wisconsin , University of Louisville and Penn State College of Medicine Since then, more than two dozen other medical schools have joined the group with each of the member schools developing their own unique version of a three-year MD degree or other accelerated curricula leading to the MD. All students in the University of Arizona's three-year program will be required to complete the same core coursework and clerkships as those in its four-year program. The accelerated pathway shaves time off the degree by eliminating some electives in the curriculum and the transition-to-residency coursework that's usually offered in the fourth year. According to the news release, Arizona currently meets only 39.2% of its primary care physician needs and requires an additional 600 primary care physicians to satisfy that need. The university projects that 2,000 more physicians will be needed by 2030 to serve the state's growing population. The College of Medicine – Tucson's program will focus on competency-based education and provide a pathway to a family medicine residency. The College of Medicine – Phoenix will emphasize early immersion in clinical experiences during medical students' first and second years, providing direct interactions with faculty members from a primary care residency program. The two medical schools hope to enroll a combined 36 medical students in the accelerated program across the next three years. The first cohort will begin this fall. According to CAMPP, three-year MD programs have several advantages. They appeal to future doctors who may opt for primary care specialties like family medicine, internal medicine and pediatrics. They reduce the total cost of medical school and help minimize student debt loads. And, as in Arizona, they tackle the problem of doctor shortages, increasing the capacity of states to offer primary medical care, especially in underserved communities.
