Philippa Kaur

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  • 125 Shares199 Views

    in Space & Astronomy

    Astronomers are puzzled over an enigmatic companion to a pulsar

    Circling around a pulsar in our galaxy is a mysterious entity that is either a very heavy neutron star, one of the lightest black holes ever discovered, or an exotic and never-before-seen quasi-stellar object.

    The new finding comes from the MeerKAT Radio Telescope in South Africa, which carefully monitored 13 millisecond pulsars in a dense cluster of stars 40,000 light years from Earth. These pulsars are a type of neutron star that quickly spin, rotating in fractions of a second, while sending out powerful beams of radiation like a cosmic lighthouse. More

  • 138 Shares189 Views

    in Humans

    Humans first reached China thousands of years earlier than we thought

    The first members of our species to reach China might have entered the region from the northEsteban De Armas / Alamy
    Modern humans were living in what is now China by 45,000 years ago. The finding means our species reached the area thousands of years earlier than generally thought, possibly via a northerly route through modern-day Siberia and Mongolia.
    A team co-led by Francesco d’Errico at the University of Bordeaux in France re-examined an archaeological site called Shiyu in northern China. It was originally excavated in 1963 during the unrest of China’s cultural revolution. “This was not the best moment to find such an important site,” says d’Errico.

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    Shiyu is an open-air site in a river gully. It holds a 30-metre-deep deposit of sands and other sediment, which the original excavators divided into four horizontal layers, the second from bottom of which was found to hold evidence of human occupation.
    The excavators found over 15,000 stone artefacts and thousands of animal bones. There was also a single piece of hominin skull, which anthropologist Woo Ru-Kang identified as a modern human (Homo sapiens).
    Some of the artefacts were later transferred to the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. But those left at the local facilities – including the hominin bone – were lost. “We have perhaps 10 per cent of the stone tools,” says d’Errico.
    D’Errico and his colleagues have re-excavated Shiyu to determine its age. They dated 15 samples of sediment using a technique called optically stimulated luminescence, and carbon-dated 10 animal bones and teeth. The hominin layer is about 44,600 years old.
    D’Errico is confident that the skull was correctly identified, as the excavators were “knowledgeable”.
    The Shiyu hominins were probably H. sapiens, says Arina Khatsenovich at the Institute of Archaeology and Ethnography in Novosibirsk, Russia, who was not involved in the study.
    As such, the new study implies modern humans had reached northern China about 45,000 years ago. This pushes back our species’ arrival in China by about 5000 years. D’Errico argues the next oldest H. sapiens site in China is Tianyuan cave, which is 40,000 years old.
    Some researchers have claimed our species arrived earlier, potentially up to 260,000 years ago. But d’Errico points out that researchers have critiqued much of the evidence for such an early human presence in the region.
    It may be that, as humans entered Asia from Africa, they spread out via multiple routes, says Khatsenovich. As well as exploring the tropical southern regions of Asia, they also went further north. Khatsenovich says there are signs of a modern human presence in this region, including at Obi-Rakhmat Grotto in Uzbekistan from 48,800 years ago. It may be that our species reached Shiyu, and China, via this northern route.

    As modern humans reached new areas, they encountered hominins that already lived there like the Neanderthals and, further east, the Denisovans. Genetic evidence has shown we interbred with them. There may also have been cultural exchanges: the artefacts at Shiyu include some that look more like archaic human tools.
    There is also evidence of long-distance exchanges. The Shiyu team identified four pieces of obsidian, a volcanic glass. They were able to trace them to sites 800 and 1000 kilometres north-east of Shiyu. D’Errico says it is unlikely the inhabitants travelled these distances themselves, so they were probably part of a network of groups. In line with this, Khatsenovich says some of the Shiyu artefacts resemble pieces found in Korea, far to the east.

    Topics:archaeology/humans More

  • 138 Shares139 Views

    in Humans

    Ancient cities discovered in the Amazon are the largest yet found

    Lidar scans of the Upano valley in Ecuador showing raised platformsStephen Rostain
    Aerial surveys have revealed the largest pre-colonial cities in the Amazon yet discovered, linked by an extensive network of roads.

    “The settlements are much bigger than others in the Amazon,” says Stéphen Rostain at the French National Center for Scientific Research in Paris. “They are comparable with Maya sites.”Advertisement
    What’s more, at between 3000 and 1500 years old, these cities are also older than other pre-Columbian ones discovered in the Amazon. Why the people who built them disappeared isn’t clear.
    It is often assumed that the Amazon rainforest was largely untouched by humans before the Italian explorer Christopher Columbus reached the Americas in the 15th century. In fact, the first Europeans reported seeing many farms and towns in the region.
    These reports, long dismissed, have in recent decades been backed up by discoveries of ancient earthworks and extensive dark soils created by farmers. One estimate puts the pre-Columbian population of the Amazon as high as 8 million.
    Rostain and his colleagues have been studying archaeological sites in the Upano valley of the Ecuadorian Amazon, in the foothills of the Andes, since the 1990s. Traces of ancient settlements were first found there in the 1970s, but only a handful of sites have been excavated.
    In 2015, Rostain’s team did an aerial survey with lidar, a laser scanning technique that can create a detailed 3D map of the surface beneath most vegetation, revealing features not normally visible to us. The findings, which have only now been published, show that the settlements were far more extensive than anyone realised.
    The survey revealed more than 6000 raised earthen platforms within an area of 300 square kilometres. These are where wooden buildings once stood – excavations have revealed post holes and fireplaces on these structures.
    Most platforms are around 10 by 20 metres and 2 metres high, and are thought to be the former sites of houses. The largest is 40 by 140 metres and 5 metres high, and was thought to be the site of monumental buildings used for ceremonies.
    Around the platforms were fields, many of which were drained by small canals dug around them. “The valley was almost completely modified,” says Rostain.
    Analysis of pottery suggests that maize, beans, manioc and sweet potatoes were grown.
    Overall there were five major settlements in the area surveyed. They could be described as garden cities, says Rostain, due to their low density of buildings.
    The survey also revealed a network of straight roads created by digging out soil and piling it on the sides. The longest extends for at least 25 kilometres, but might continue beyond the area that was surveyed.
    The Upano valley in EcuadorStephen Rostain
    What is peculiar is that the Upano people went to great lengths to make the roads straight, says Rostain. In places they dug down 5 metres rather than follow contours, for instance. So the roads probably had symbolic significance, as there was no practical reason to make them straight, he says.
    In places there are also signs of defensive structures such as ditches, so there may have been some conflict between groups.
    In the rest of the Amazon, many settlements were abandoned after the arrival of Europeans, probably because diseases and violence unleashed by the invaders killed a large proportion of the population.
    All the Upano artefacts dated by Rostain’s team are older than 1500 years, however, suggesting the settlements in the valley were abandoned after this time, long before the colonial era. Why isn’t clear, but the team has found layers of volcanic ash, so it is possible a series of eruptions forced people to leave the valley.

    “This shows an unprecedented degree of complexity and density of settlement for this early time frame,” says Michael Heckenberger at the University of Florida. “The authors justifiably conclude that the complexity and scale are comparable with better known cases, such as the Maya, at this time.”
    “This is the largest complex with large settlements so far found in Amazonia,” says Charles Clement at the National Institute of Amazonian Research in Manaus, Brazil.
    What’s more, it was found in a region of the Amazon that other researchers had concluded was sparsely inhabitated during pre-Columbian times, says Clement.

    Topics:archaeology More

  • 163 Shares129 Views

    in Space & Astronomy

    The strongest known fast radio burst has been traced to a 7-galaxy pileup

    NEW ORLEANS — A mind-bogglingly strong spurt of electromagnetic energy has for the first time been traced back to a cluster of seven merging galaxies. The finding could bolster the hypothesis that such mysterious flareups, known as fast radio bursts, originate from bizarre, highly magnetized dead stars called magnetars.

    Fast radio bursts, or FRBs, are fleeting explosive events: They last fractions of a second but release as much energy as the sun does in a month. It remains unclear what causes these strange spectacles, first discovered in 2007 (SN: 7/25/14). More

  • 125 Shares169 Views

    in Space & Astronomy

    Salt may have carved out Mercury’s terrains, including glacierlike features

    Mercury’s surface might not be quite so terra firma, at least on geologic timescales.

    The closest planet to the sun is a world sculpted by volatiles — ephemeral compounds that can freeze, flow or float into space over time, analogous to water on Earth. Salt, the primary volatile on Mercury, appears to have reshuffled the planet’s landscape over billions of years and might even flow — very slowly — in glacierlike landforms, researchers report in the November Planetary Science Journal. The volatile could possibly even form habitable niches deep underground, the authors speculate. More

  • 175 Shares99 Views

    in Space & Astronomy

    A bar of stars at the center of the Milky Way looks surprisingly young

    The biography of our home galaxy may be due for some revisions. That’s because a bar-shaped collection of stars at the center of the Milky Way appears to be much younger than expected.

    The bar is a prominent feature of our galaxy (SN: 6/25/21). It spans thousands of light-years and links the galaxy’s spiraling arms of stars, making them resemble streams of water coming from a spinning lawn sprinkler. In computer simulations of the Milky Way’s evolution, the bar tends to form early in the galaxy’s roughly 13-billion-year lifetime. But the ages and locations of metal-rich stars suggest the bar finished forming just a few billion years ago, researchers report. The study, submitted November 28 to arXiv.org, is in press at Astronomy & Astrophysics Letters.

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    “These metal-rich stars are basically like fossil records of ancient stars that are telling the story of our home galaxy,” says Samir Nepal, an astrophysicist at the Leibniz Institute for Astrophysics Potsdam in Germany.

    Stars with large proportions of metal elements are built from the remnants of stars that have since exploded, ejecting the metals they forged from lighter elements. Those spewed metals enrich the materials in the core of galaxies like the Milky Way, which is why a new generation of metal-rich stars can form only deep inside galaxies. The spinning bar at the center of the Milky Way then scattered some of those stars throughout our galaxy.

    Using data from the European Space Agency’s Gaia space telescope, Nepal and colleagues reconstructed the development of the Milky Way bar through its influence on the distribution of metal-rich stars (SN: 5/9/18). They inferred the bar’s history, just as you might deduce where the batters stand in a baseball game by looking at the flight of the balls they hit, even if you can’t see home plate.

    In tracking the ages of the metal-rich stars, the researchers identified a burst of star formation in the central part of the galaxy that petered out about 3 billion years ago. The downturn seems to mark the end of the Milky Way bar’s developmental phase, the researchers report. After that burst, they say, the inflow of new material into the bar probably dropped off substantially. That suggests the bar we see today is a stable feature that’s about 10 billion years younger than the galaxy as a whole.

    The new insights about the metal-rich stars “are like the tip of the iceberg” of data coming from the Gaia telescope, says astrophysicist Cristina Chiappini, also with the Leibniz Institute for Astrophysics Potsdam. Assuming the revised age estimate of the bar is confirmed, future models of the galaxy’s evolution will have to account for why the bar developed so late.

    The study has broader implications than correcting the history of our galaxy, says Ortwin Gerhard, an astrophysicist at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, who was not involved in the research. “The possibility of detailed observations of the motions and chemical abundances of stars in the Milky Way, particularly based on [data] from the Gaia satellite,” he says, means we can “expect to learn about the evolution of bars [in other galaxies] generally by studying the bar in the Milky Way.” More

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    in Humans

    The 2023 discoveries that made us rethink the story of human evolution

    Stone age paintings in Chauvet cave in FranceFine Art Images/Heritage Images/Getty Images
    This is an extract from Our Human Story, our newsletter about the revolution in archaeology. Sign up to receive it in your inbox for free every month.
    At this point it’s a truism that the story of human evolution is being rethought. Discoveries in recent years have forced us to rethink many crucial points, such as how old our species is – about 300,000 years old as opposed to 200,000 – and what extinct hominins like the Neanderthals were really like.
    2023 was equally dizzying: discoveries continued to come thick and fast. But because there are so many species and eras involved, it’s hard to discern the common threads linking them – at least, beyond “we found out some more stuff”.Advertisement
    However, I do think it’s possible to draw out some overall messages from the blizzard of archaeological finds. Two things stand out to me. One is the growing evidence that many supposedly “advanced” behaviours, such as architecture and art, can be traced much further back in time than we thought, often to hominins that existed before modern humans. And the other is that we have badly misunderstood gender roles in prehistoric societies, imposing patriarchal values onto cultures that had very different ideas about how women should behave.

    Ancient achievements
    Let’s start with architecture. At Kalambo Falls in Zambia, researchers found buried logs that had been shaped with stone tools so that they interlocked. They seem to have once been part of a larger structure, perhaps a building. Which would be unsurprising if they weren’t 476,000 years old. That’s almost 200,000 years before our species, Homo sapiens, evolved.
    Extinct hominins also managed to settle in extreme places. For instance, we now know that hominins like the Denisovans lived on the frigid heights of the Tibetan plateau 200,000 years ago – upending the old notion that the plateau was only settled by modern humans around 3600 years ago.
    Art also seems to have been invented by older hominins. We already had evidence that Neanderthals painted on cave walls, and 2023 saw more Neanderthal art from La Roche-Cotard cave in France. Even earlier species like Homo erectus may also have made art, for example by engraving patterns on shells.
    By far the most contentious claim in this area is that Homo naledi made art. H. naledi lived around 250,000 years ago, making it a contemporary of our species. However, it had quite a small brain, typical of older hominins – and was therefore, according to palaeoanthropological dogma, incapable of complex behaviours.
    Nevertheless, in the Rising Star cave system in South Africa where the H. naledi remains were found, researchers have found what seem to be etchings on the cave walls, though these have yet to be firmly dated. They also claim to have found evidence of H. naledi burying their dead in the cave. These assertions were the subject of a Netflix documentary, Cave of Bones.

    To say these claims are controversial is to understate the situation. Many researchers say the evidence presented so far is completely inadequate to support them. The dispute has only been heightened by the way the results were released, in a non-traditional journal that publishes peer reviews publicly alongside the paper.
    My views on the H. naledi controversy are complicated. I do think more evidence is needed: in particular, I want to know how old the engravings are. At the same time, I think the species’ small brains are a distraction. Palaeoanthropologists got fixated on brain size because it was what they could see: if what you have is skeletons, then all you know about brains are their shapes and sizes. But other properties like the brain’s internal wiring are surely equally important and may explain how a species like H. naledi could do complicated things despite their small brains.
    In a sense, we shouldn’t be surprised that so many of these behaviours had their origins in older, extinct hominins. Evolution usually works by gradual steps, and so does technology – the first birds weren’t great at flying, and the first mobile phones weren’t great at, well, anything really.
    The idea that there was a sudden explosion of intelligence and creativity at some point in our evolution isn’t inherently ridiculous: sometimes a system hits a tipping point and undergoes runaway change. But there was never that much evidence that human evolution worked this way. Instead, it seems that Homo erectus, the Neanderthals and many others all walked so we could run.

    Alternative societies
    One way or another, the H. naledi story is going to be an example of letting our preconceptions get in the way of the evidence. The same is true for our ideas about gender in prehistory. Archaeology was invented by societies with sexist ideas, and those notions bled into the research (see also: scientific racism and homophobia). Researchers are now trying to unpick this stuff, and 2023 saw some significant steps.
    Perhaps the most dramatic was the demolition of “Man the Hunter”. This was the idea, promoted for decades, that in most prehistoric societies the men went out to hunt and the women stayed home. However, a meta-analysis published in June compiled data on several dozen foraging societies and found women hunted in 80 per cent of them. In line with this, it emerged that an ancient spear-throwing tool called an atlatl enables women to launch projectiles at the same speed as men.

    We have also seen growing evidence of women occupying positions of power in ancient societies. The Viking queen Thyra may have helped unify Denmark in the 900s. Going further back, an Iberian leader from around 4000 years ago turned out to be female, not male as many had assumed, when proteins in her teeth were analysed.
    So I want to end 2023 on a hopeful note. The more we learn about past societies, the more our preconceptions about the ways society “has to be” turn out to be wrong. Inequality, authoritarianism and patriarchy aren’t inevitable. They’re choices, and prehistory shows us that we can choose differently.

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