Latest news with #ScienceAdvances
Yahoo
15 hours ago
- Science
- Yahoo
Neanderthal extinction: a space physicist reopens the debate
Neanderthals have long been the subject of intense scientific debate. This is largely because we still lack clear answers to some of the big questions about their existence and supposed disappearance. One of the latest developments is a recent study from the University of Michigan, published in the journal Science Advances. It proposes that Neanderthals went extinct for astrophysical reasons. The work was led by Agnit Mukhopadhyay, an expert in space physics, a discipline that studies natural plasmas, especially those found within our own solar system. Plasma is the state of matter that dominates the universe: the Sun and stars are huge balls of plasma, as are the northern lights. Mukhopadhyay's research suggests that a shift in the Earth's magnetic poles around 41,000 years ago, known as the Laschamp event, may have contributed to the extinction of Neanderthals. According to his work, the extreme weakening of the Earth's magnetic field during that event allowed for greater penetration of cosmic and ultraviolet radiation. This would have generated more aggressive environmental conditions that Neanderthals could not withstand, giving our own species, Homo sapiens, an edge. In this context, sapiens would have had an advantage over Neanderthals thanks to their presumed use of close-fitting clothing, ochre – a mineral with protective properties against the sun – and taking shelter in caves. Caves which, by the way, on numerous occasions were inhabited by both Neanderthals and our own species. The hypothesis is interesting, and is based on innovative three-dimensional models of the Earth's geospatial system during this period. However, as with many hypotheses that attempt to explain complex phenomena on the basis of a single variable, its scope and some of the assumptions on which it is based need to be examined more closely. One of the pillars of this hypothesis is that Neanderthals did not wear tight-fitting clothing, and would therefore have been more exposed to the harmful effects of solar radiation. It is true that sewing needles have not been definitvely linked to Neanderthals. The first needles documented in Eurasia are associated with either Denisovan or sapiens populations around 50,000 years ago, and in western Europe they did not appear until around 23,000 years ago. But this does not mean that Neanderthals did not wear clothing. In fact, the Homo sapiens who lived during episodes of extreme cold (such as the Heinrich 4 event, which occurred some 39,600 years ago) did not have sewing needles either, but they did have enough technology to make garments, and possibly tents and footwear. There is ample archaeological evidence of Neanderthals processing hides, such as the systematic use of scrapers and other tools associated with the tanning process. However, the use of fur or clothing has much older origins. In fact, the genetic study of lice has revealed that humans were already wearing clothing at least 200,000 years ago. Furthermore, in cold environments such as those they inhabited in Europe, it would have been unfeasible to survive without some form of body protection. Even if they did not have needles, it is very plausible that they used alternative systems such as ligatures or bone splinters to adapt animal hides to the body. The absence of needles should not be confused with the absence of functional clothing. The study also highlights the use of ochre by Homo sapiens, which it says offered protection against solar radiation. Although experiments have been carried out to demonstrate certain blocking capacities of ochre against ultraviolet (UV) rays, its use by human populations is not limited to a single group. In fact, evidence of pigment use during the same period has been found in Africa, the Near East and the Iberian Peninsula, and among different human lineages. The use of ochre has been documented in Neanderthal contexts for more than 100,000 years, both in Europe and in the Levant. Its application may have had multiple purposes: symbolic, therapeutic, cosmetic, healing, and even an insect repellent. There are no solid grounds for claiming that its use for protective purposes was exclusive to Homo sapiens, especially when both species shared spaces and technologies for millennia. Nor can we be sure that it was used as a protective sunscreen. Leer más: One of the most significant factors may have been the marked difference in population size. There were fewer Neanderthals, meaning they would have been assimilated by the much more numerous populations of Homo sapiens. This assimilation is reflected in the DNA of current populations, suggesting that, rather than becoming extinct, Neanderthals were absorbed into the evolutionary process. Technology also played a part– as far as we know, Neanderthals did not use hunting weapons at a distance. The invention and use of projectiles associated with hunting activities – first in stone and later in hard animal materials – appear to be an innovation specific to Homo sapiens. Their development may have given them an adaptive advantage in open environments, and a greater capacity to exploit different prey and environments. Leer más: Associating the Neanderthal 'extinction' to their supposed failure to adapt to increased solar radiation during the Laschamp excursion oversimplifies a phenomenon that remains the subject of heated debate. Put simply, the archaeological record does not support Mukhopadhyay's hypothesis. There is no evidence of an abrupt demographic collapse coinciding with this geomagnetic event, nor of a widespread catastrophic impact on other human or animal species. Moreover, if solar radiation had been such a determining factor, one would expect high mortality also among populations of sapiens that did not wear tight clothing or live in caves (in warm regions of Africa, for instance). As far as we know, this did not happen. When trying to explain the disappearance of Neanderthals, it is vital that we integrate multiple lines of archaeological, paleoanthropological and genetic evidence. These humans were not simply victims of their own technological clumsiness or of a hostile environment that they failed to cope with. They were an adaptive and culturally complex species that, for more than 300,000 years, survived multiple climatic changes – including other geomagnetic shifts such as the Blake event, which occurred about 120,000 years ago. Neanderthals developed sophisticated tools, dominated vast territories and shared many more traits with us than was assumed for decades. So did the magnetic reversal of the Earth's magnetic poles wipe out the Neanderthals? The answer is: probably not. Este artículo fue publicado originalmente en The Conversation, un sitio de noticias sin fines de lucro dedicado a compartir ideas de expertos académicos. Lee mas: Neanderthals: the oldest art in the world wasn't made by Homo sapiens Modern human DNA contains bits from all over the Neanderthal genome – except the Y chromosome. What happened? How Neanderthal language differed from modern human – they probably didn't use metaphors Las personas firmantes no son asalariadas, ni consultoras, ni poseen acciones, ni reciben financiación de ninguna compañía u organización que pueda obtener beneficio de este artículo, y han declarado carecer de vínculos relevantes más allá del cargo académico citado anteriormente.
Daily Maverick
20 hours ago
- Science
- Daily Maverick
New research strengthens case for age of ancient New Mexico footprints
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.'
Yahoo
3 days ago
- Science
- Yahoo
As Earth's Magnetic Field Grows Stronger, Oxygen Levels Rise
When the magnetic field around the Earth grows stronger, oxygen levels rise. That is the surprising finding of a new study looking at more than half a billion years of planetary history. Researchers can track the rise and fall in oxygen levels by studying charcoal left over from ancient wildfires. The more oxygen, the larger the fires. And they can gauge changes in the geomagnetic field by studying rocks formed by ancient volcanic eruptions. Magnetic crystals found in cooling lava align with the geomagnetic field, offering some indication of its strength. The new study combined these data, revealing a powerful link between oxygen levels and the strength of the geomagnetic field. Over the last 540 million years, the strength of the magnetic field has trended up, and so has the level of oxygen, making the planet more hospitable to life. The findings were published in Science Advances. 'We don't really have a good explanation for it,' coauthor Benjamin Mills, of the University of Leeds, told Nature, though he offered a few ideas. As the tectonic plates have shifted, over hundreds of millions of years, their movements have, at times, unleashed essential nutrients, such as zinc and phosphorus, into the ocean, fueling massive algal blooms. Those blooms produced huge volumes of oxygen. It may be the case, scientists propose, that the same currents driving the movement of the tectonic plates may also be affecting the Earth's iron core, the source of its magnetic field. Can Toxic Mining Waste Help Remove CO2 from the Atmosphere?
NDTV
12-06-2025
- Science
- NDTV
6,000-Year-Old Skeletons Have Distinctive DNA With No Link To Modern Humans
In a major archaeological breakthrough, scientists revealed that ancient human remains, unearthed in the Bogota Altiplano in central Colombia, do not match any indigenous human population in the region. The skeletons are 6,000 to 500 years old, and the study revealed that some of the individuals belonged to a previously unknown population. A team of researchers studied the genetic data of 21 individuals and published findings in the journal Science Advances in May. Earlier studies have revealed that two lineages existed - northern Native American and southern Native American. It developed when people started to move south after first arriving on the continent from Siberia. The southern Native American is further divided into at least three sub-lineages. However, scientists have yet to find the exact time and other details when the first people would have moved from Central America to South America. "We show that the hunter-gatherer population from the Altiplano dated to around 6000 yr B.P. lack the genetic ancestry related to the Clovis-associated Anzick-1 genome and to ancient California Channel Island individuals," the study noted. "The analysed Preceramic individuals from Colombia do not share distinct affinity with any ancient or modern-day population from Central and South America studied to date," the study added. "Colombia_Checua_6000BP can thus be modeled as a previously undescribed distinct lineage deriving from the radiation event that gave rise to multiple populations across South America during its initial settlement," it mentioned. The study author, Andrea Casas Vargas, a researcher at the Universidad Nacional de Colombia, told CNN on Wednesday (June 11) that the research team was "very surprised" with the findings. "We did not expect to find a lineage that had not been reported in other populations," Vargas added. Kim-Louise Krettek, lead author and a PhD student at the Senckenberg Center for Human Evolution in Germany, said, as quoted by Express UK, that this area is key to understanding "how the Americas were populated". "It was the land bridge between North and South America and the meeting point of three major cultural regions: Mesoamerica, Amazonia, and the Andes." Krettek added. The study is very important, Vargas said, adding that it is the first to sequence complete genomes in ancient samples from Colombia. Vargas said that the results raise questions "as to where they came from and why they disappeared. "We are not certain what happened at that time that caused their disappearance, whether it was due to environmental changes, or if they were replaced by other population groups," she said, further adding that more research will provide some answers, hopefully.
Yahoo
11-06-2025
- Science
- Yahoo
6,000-year-old skeletons found in Colombia have unique DNA
Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. Scientists studying ancient human remains uncovered in Colombia have found that the people they were researching have no known ancestors or modern descendants. In a study published May 30 in the journal Science Advances, a team of researchers reported on the genetic data of 21 individuals whose skeletal remains were found in the Bogotá Altiplano in central Colombia, some of whom lived as long as 6,000 years ago, that belonged to a previously unknown population. Previous studies have proven the existence of two lineages, northern Native American and southern Native American, which developed after people first arrived on the continent across an ice bridge from Siberia and started to move south. The latter split into at least three sub-lineages whose movements have been traced in South America, but scientists have not yet ascertained when the first people would have moved from Central America to South America. The study helps to map the movements of the first settlers, who would have been nomadic hunter-gatherers, study author Andrea Casas Vargas, a researcher at the Universidad Nacional de Colombia, told CNN on Wednesday, but it also found that they have unique DNA. Casas Vargas said the team were 'very surprised' to find that the remains did not share DNA with other people in the genetic record. 'We did not expect to find a lineage that had not been reported in other populations,' she said. Casas Vargas underlined that Colombia's position as the entry point to South America makes it significant to our understanding of the population of the Americas. 'This study is very important because it is the first to sequence complete genomes in ancient samples from Colombia,' she said, The results raise questions 'as to where they came from and why they disappeared,' said Casas Vargas. 'We are not certain what happened at that time that caused their disappearance, whether it was due to environmental changes, or if they were replaced by other population groups,' she added. Further research will hopefully provide some answers, said Casas Vargas. 'Our next investigations will look for other archaeological remains from other regions of the country and analyze them at the genetic level and complement this first discovery,' she said. Christina Warinner, a professor of scientific archaeology at Harvard University, told CNN that Colombia 'is a key region for understanding the peopling of South America… but until now it has been a blank spot in ancient DNA studies of the Americas.' 'This study highlights the deep history of population migration and mixing in the formation today's populations, and points to Central America as a key region that influenced the development of complex societies in both North and South America,' she added.
