Latest news with #HomoSapiens
Japan Times
5 hours ago
- Science
- Japan Times
Humans adapted to diverse habitats before trekking out of Africa
Small bands of Homo sapiens made a few failed forays leaving our home continent before the species finally managed to launch a major dispersal out of Africa roughly 50,000 years ago, going first into Europe and Asia and eventually the rest of the world. So why was this migration successful after the prior ones were not? New research is offering insight. It documents how human hunter-gatherers in Africa began about 70,000 years ago to embrace a greater diversity of habitats such as thick forests and arid deserts, acquiring an adaptability useful for tackling the wide range of conditions awaiting beyond the continent. "Why the dispersal 50,000 years ago was successful is a big question in human origins research. Our results suggest that one part of the reason is that humans had developed the ecological flexibility to survive in challenging habitats," said Loyola University Chicago archeologist Emily Hallett, co-leader of the study published in the journal Nature. Looking at an array of archeological sites in Africa, the study detailed how human populations expanded their range into the forests of Central and West Africa and the deserts of North Africa in the roughly 20,000 years preceding this dispersal. Some examples of archeological sites dating to this time that illustrate the expansion of human niches to harsh deserts include locales in Libya and Namibia, and examples of expansion to forested habitats include locales in Malawi and South Africa. Homo sapiens arose roughly 300,000 years ago, inhabiting grasslands, savannahs and various other African ecosystems. Impalas graze at the Singita Grumeti Game Reserve in Tanzania. | REUTERS "Starting from about 70,000 years ago, we see that they suddenly start to intensify this exploitation of diverse habitats and also expand into new types of habitat in a way we don't see before. They exploit more types of woodland, more types of closed canopy forests, more types of deserts, highlands and grasslands," said archeologist and study co-leader Eleanor Scerri of the Max Planck Institute of Geoanthropology in Germany. "An Ice Age was coming, which means drier conditions in parts of Africa. It seems possible that humans responded to this squeeze by learning how to adapt to new niches," Scerri added. The increased ecological flexibility of the species appears to have reflected cultural and social advances such as passing knowledge from one generation to the next and engaging in cooperative behavior, the researchers said. "This must have entailed profound changes in their interaction with the natural environment, as it allowed them to occupy not only new environments in Africa, but entirely new conditions in Eurasia as well," said evolutionary biologist and study co-leader Michela Leonardi of the Natural History Museum in London. "Another way to phrase this is that the ability to live in a variety of environments in Africa is not directly the adaptation that allowed a successful out of Africa, but rather a sign that humans by that point were the ultimate generalist, able to tackle environments that went from deep forest to dry deserts," said University of Cambridge evolutionary ecologist and study co-leader Andrea Manica. "This flexibility is the key trait that allowed them, later on, to conquer novel challenges, all the way to the coldest tundras in Siberia." Trekking out of Africa, Homo sapiens encountered not only new environments and unfamiliar animals and plants, but also other human species, including the Neanderthals and Denisovans. The ecological flexibility learned in Africa may have provided an edge when Homo sapiens encountered these other humans, both of whom disappeared relatively soon thereafter, the researchers said. Genetic evidence indicates that today's people outside of Africa can trace their ancestry to the population of humans, numbering perhaps only in the thousands, who engaged in that pioneering migration out of Africa approximately 50,000 years ago. "I think that adaptability and innovation are hallmarks of our species, and that they allowed us to succeed in every environment we encountered," Hallett said. "At the same time, we are almost too good at adapting to different places, to the detriment of most other species on Earth."
Yahoo
16 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.
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."
Yahoo
2 days ago
- Science
- Yahoo
Early humans adapted to extreme habitats. Researchers say it set the stage for global migration
WASHINGTON (AP) — Humans are the only animal that lives in virtually every possible environment, from rainforests to deserts to tundra. This adaptability is a skill that long predates the modern age. According to a new study published Wednesday in Nature, ancient Homo sapiens developed the flexibility to survive by finding food and other resources in a wide variety of difficult habitats before they dispersed from Africa about 50,000 years ago. 'Our superpower is that we are ecosystem generalists,' said Eleanor Scerri, an evolutionary archaeologist at the Max Planck Institute of Geoanthropology in Jena, Germany. Our species first evolved in Africa around 300,000 years ago. While prior fossil finds show some groups made early forays outside the continent, lasting human settlements in other parts of the world didn't happen until a series of migrations around 50,000 years ago. 'What was different about the circumstance of the migrations that succeeded — why were humans ready this time?' said study co-author Emily Hallett, an archaeologist at Loyola University Chicago. Earlier theories held that Stone Age humans might have made a single important technological advance or developed a new way of sharing information, but researchers haven't found evidence to back that up. This study took a different approach by looking at the trait of flexibility itself. The scientists assembled a database of archaeological sites showing human presence across Africa from 120,000 to 14,000 years ago. For each site, researchers modeled what the local climate would have been like during the time periods that ancient humans lived there. 'There was a really sharp change in the range of habitats that humans were using starting around 70,000 years ago,' Hallet said. 'We saw a really clear signal that humans were living in more challenging and more extreme environments.' While humans had long survived in savanna and forests, they shifted into everything from from dense rainforests to arid deserts in the period leading up to 50,000 years ago, developing what Hallet called an "ecological flexibility that let them succeed.' While this leap in abilities is impressive, it's important not to assume that only Homo sapiens did it, said University of Bordeaux archaeologist William Banks, who was not involved in the research. Other groups of early human ancestors also left Africa and established long-term settlements elsewhere, including those that evolved into Europe's Neanderthals, he said. The new research helps explain why humans were ready to expand across the world way back when, he said, but it doesn't answer the lasting question of why only our species remains today. ___ The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute's Science and Educational Media Group and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.
