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    in Humans

    Climate change may have driven early human species to extinction

    By Donna Lu
    Was Homo erectus driven extinct by climate change?
    The Natural History Museum/Alamy

    Sudden climatic changes may have been a significant driver of the extinction of early human species.
    Pasquale Raia at the University of Naples Federico II in Italy and his colleagues have used climate modelling and fossil records to determine the effect climate change had on the survival of the species in our Homo genus.
    The researchers used a database of 2754 archaeological records of the remains of several species alive over the past 2.5 million years, including Homo habilis, Homo ergaster, Homo erectus, Homo heidelbergensis, Homo neanderthalensis and Homo sapiens.

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    They cross-referenced these records with a climate emulator, which modelled temperature, rainfall and other weather data over the past 5 million years. The aim was to determine the climatic niche for each species – a range of conditions including temperature and precipitation that are optimal for survival – and how widely distributed the niche area was through time.
    The team found that H. erectus, H. heidelbergensis and H. neanderthalensis all lost a significant portion of their climatic niche area just before they became extinct.

    “Species are good at surviving when they have a large area at their disposal to live in,” says Raia. But when liveable areas decrease and the result is small patches that are geographically isolated from each other, species enter what is known as an extinction vortex.
    The reductions in liveable area resulted from sudden climatic changes, the team found. H. erectus, for example, went extinct during the last glacial period, which began about 115,000 years ago. The researchers suggest this was the coldest period the species had ever experienced.
    The team found that for the Neanderthals, competition with H. sapiens was also a factor, but that even without the presence of our species the effect of climate change alone may have been enough to lead to extinction. Even species with the ability to control their local environment – such as by wearing clothes or creating fires – were susceptible to the effects of climate change, says Raia.

    But gaps in data may compromise the certainty of the conclusion that climate change was the primary extinction driver, say researchers who weren’t involved in the study.

    Aside from Neanderthals, there is scarcely any fossil evidence for the other species studied, says Bernard Wood at George Washington University in Washington DC. “Individuals belonging to these taxa lived at times, and in places, not sampled by the existing fossil record,” he says.
    “Plus, the first appearance date of a taxon almost certainly underestimates when a taxon appeared, and its last appearance date almost certainly underestimates when a taxon became extinct,” he says.
    As species approach extinction, regardless of the cause – whether it be competition, being hunted or breeding problems – their range necessarily declines, says Corey Bradshaw at Flinders University in Australia. If a species’ range was already in decline, that could give the false impression that the climate niche area was also declining, he says.
    “No species that we know of has ever gone extinct from a single mechanism. It’s always a combination,” says Bradshaw. “For example, in the case of many megafauna species in the late Pleistocene, it’s coming to light that there were a lot of interaction effects between human hunting and climate change.”
    Journal reference: One Earth, DOI: 10.1016/j.oneear.2020.09.007
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    in Space & Astronomy

    A spherical star cluster has surprisingly few heavy elements

    A strange, newly measured clump of stars orbiting the nearby Andromeda galaxy has the lowest level of heavy chemical elements ever seen in one of these mysterious star clusters. Named RBC EXT8, this globular cluster is also surprisingly massive, challenging theories for how such clusters and some galaxies form, astronomers report online October 15 in Science.
    “It’s a very unusual object,” says astrophysicist Oleg Gnedin of the University of Michigan in Ann Arbor, who was not involved in the new discovery.
    Globular clusters are crowded, spherical collections of stars that orbit a galaxy’s center, though most, including RBC EXT8, live in the galactic outskirts. The clusters are typically billions of years old, so their stars tend to be chemically pristine, meaning they formed before the universe had time to create much of any of the elements heavier than hydrogen or helium, which astronomers lump together as “metals.”
    Previous observations of these clusters in the Milky Way and other galaxies had suggested that there’s a limit to how low a globular cluster’s metal content can be. The most metal-poor clusters were about 300 times less rich in heavy elements like iron than the sun, but no less.
    But spectra of RBC EXT8, some 2.5 million light-years away, show that the cluster’s metal content is about 800 times less than the sun’s. The globular cluster that held the previous record for lowest “metallicity” has three times that amount.
    “It was completely unexpected that we would find a globular cluster that is so metal poor,” says astronomer Søren Larsen of Radboud University in Nijmegen, the Netherlands.
    The bigger, fuzzy blob in the inset image at left is RBC EXT8, a globular cluster that orbits about 88,000 light-years from the center of the galaxy Andromeda (shown at right). The cluster has surprisingly few heavy elements for its size, a new study finds.© 2020 ESASky, CFHT
    What’s more, given its metal-poor status, this cluster is surprisingly massive, weighing about 1.14 million times the mass of the sun. (A mid-weight globular cluster is about 100,000 solar masses, but some clusters reach 3 million solar masses. RBC EXT8 is heavy, but not the heaviest.)
    That mass makes the cluster even harder to explain because across the cosmos, the more massive a galaxy or cluster is, the more heavy elements it normally has.
    There are several potential explanations for that trend, but one is simply that more massive galaxies or globular clusters have more stars. A star fuses heavy elements in its core and sprinkles them around its host cluster or galaxy as it ages. Sufficiently massive stars can explode in a supernova, spreading those metals to become part of the next generation of stars (SN: 8/9/19). So more stars means more opportunity for metals to accumulate locally.
    More massive objects also have the advantage of gravity, which lets them better hold on to the metals that they do have and remain a cohesive group for billions of years. Less massive globular clusters dissolve into their host galaxies over time.
    Those trends together could have explained the apparent “metallicity floor” for globular clusters — all of the less massive, more metal-poor clusters have broken apart over the eons.
    RBC EXT8 turns that conventional wisdom on its head. “It’s too big to have as low metallicity as it has,” Gnedin says. “That’s the conundrum.”

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    Astronomers aren’t sure how globular clusters form in general, but they probably grow within galaxies, rather than forming outside of them and being pulled in later. And so the clusters reflect the characteristics of their galaxies: small, metal-poor galaxies end up with small metal-poor globular clusters, and vice versa. But based on RBC EXT8’s metal content, it’s galactic birthplace would be less than a million solar masses, so smaller than the globular cluster itself – which is a paradox.
    As a result, the cluster challenges some simplified models of galaxy formation. But it doesn’t completely break them, Gnedin says. “It’s one object, it’s not going to overturn things,” he says. “It just makes us people working on these issues have to work harder” and be more open-minded about other ways that galaxies could form.
    Open-mindedness and willingness to explore is perhaps responsible for the new finding about RBC EXT8’s metals. Larsen and colleagues spotted the globular cluster at the beginning of a night of observing with the Keck telescope in Hawaii in October 2019. “It was really a serendipitous discovery,” he says. He had a spare hour before the globular clusters in galaxy M33 that his team was planning to look at rose above the horizon, so the observers picked another cluster “more or less at random” to fill the time.
    “At first, I couldn’t really believe that what was coming out [in the observations] was right,” Larsen says. “But I kept working on it, and it turned out to hold up.” More

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    in Humans

    'Ums' and 'ers' are a hidden code that helped complex language evolve

    Filler words such as uh, mmm and huh may seem inarticulate, but without them human communication would be far less sophisticated

    Humans 14 October 2020
    By David Robson

    Andy Smith

    YOU might expect it to take more than a two-letter word to sink a politician’s credibility. But one did just that for Canada’s prime minister, Justin Trudeau, in June 2016. With a huge wildfire burning in the province of Alberta, he had been asked about the country’s capacity to cope. “Uh, certainly, I think we’re, uh, all aware that, uh, uh, a prime minister, uh, showing up at Fort McMurray, when firefighters are busy trying to, uh, uh, contain a massive raging wildfire is, uh, not a particularly helpful thing,” he began. Trudeau went on to use a total of 50 uhs in a statement lasting little more than a minute.
    A video soon went viral, and online commentators were universally scathing. “Canada’s dumbest, uh, Prime Minister” wrote one viewer. Reading the unedited transcript, you may well have questioned Trudeau’s intelligence yourself. Surely such hesitation is a sign of sloppy thinking and ineloquence. Weren’t we taught as children to eliminate uhs from our conversation?
    Yet the latest research shows that this is an unfounded prejudice. Far from being an inarticulate waste of breath, filler words like um, uh, mmm and huh are essential for efficient communication, sending important signals about the words we are about to say so that two speakers can better understand each other. “They streamline our interactions, smooth the flow of the conversation and manage our social relations,” says Mark Dingemanse, who studies language and social interaction at Radboud University in the Netherlands. Indeed, he argues that the complexity of our language today couldn’t have emerged without them. To which the obvious response … More

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    in Humans

    The Book of Malachi is darkly unmissable science fiction

    The Book of Malachi by T. C. Farren centres on a young man whose tongue has been cut out during a brutal civil war. It’s a tough, mind-bending morality tale

    Humans 14 October 2020

    Victor Moussa/Alamy

    The Book of Malachi
    T. C. Farren
    Titan
    THE main problem with this book is you aren’t going to want to read it. But it’s good and you should.
    Malachi Dakwaa, the eponymous character in T. C. Farren’s novel, is a young man whose tongue was cut out in a brutal civil war. In the years since, he has eked out a half-life as a quality control manager at a chicken processing plant, ensuring the uniform compliance of shrink-wrapped body parts.
    One day, he gets an offer for a job he didn’t apply for, with a payment he … More

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    in Humans

    Stone Age people in Ireland had dark skin and were lactose-intolerant

    By Michael Marshall
    View from the chamber entrance on Bengorm mountain, Ireland
    Thorsten Kahlert

    Some Stone Age people in Ireland left the bodies of their dead to decompose in a natural rocky chamber on a mountain. Genetic analysis of two of these bodies shows they had darker skin, like many people in Europe at the time, and suggests they lived in fairly large communities.
    The boulder chamber was accidentally discovered in 2016 by a hillwalker exploring Bengorm mountain in north-west Ireland. Finding human bones on the floor, he called the police. The bones turned out to be thousands of years old and the … More

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    in Space & Astronomy

    The asteroid Bennu’s brittle boulders may make grabbing a sample easier

    When NASA’s OSIRIS-REx arrived at near-Earth asteroid Bennu, scientists were dismayed to find a surface covered with hazardous-looking boulders.
    But new research suggests that those boulders are surprisingly brittle. That’s potentially good news for the spacecraft, which is charged with grabbing a piece of Bennu on October 20 and returning it to Earth in 2023 (SN: 1/15/19). If the rocks are crumbly, that could lower the risk of damaging the spacecraft’s equipment.
    That kind of rock also may be too fragile to survive the trip through Earth’s atmosphere without burning up. If so, scientists may be close to getting their hands on a never-before-seen kind of space rock, researchers report in a collection of papers published October 8 in Science and Science Advances.
    Data taken from Earth before OSIRIS-REx launched suggested that Bennu’s surface would be sandy. So it was a shock to find a rough landscape strewn with boulders when the spacecraft arrived in 2018 (SN: 12/3/18).
    “We had really convinced ourselves that Bennu was a smooth object,” says Daniella DellaGiustina, a planetary scientist at the University of Arizona in Tucson and member of the OSIRIS-REx team. “As everyone saw from the first pictures, that was not the case.”
    The team found a relatively clear crater, nicknamed Nightingale, from which to retrieve a sample of the space rock (SN: 12/12/19). Still, the worry remains that the boulders might pose a safety hazard for the sampling system, which was designed to handle pebbles only a few centimeters across.
    From late April through early June 2019, planetary scientist Ben Rozitis of the Open University in Milton Keynes, England, and colleagues mapped the way Bennu’s boulders retain heat, a clue to the rocks’ structure. Denser materials hold heat better than finer-grained ones, like how a sandy beach cools quickly after sundown, but single large rocks remain warm.
    This map shows where carbon-bearing minerals (represented by redder colors) are located on Bennu’s surface. The opportunity to analyze those minerals could help scientists figure out how carbon got to the early Earth.A. Simon et al/Science 2020
    Based on those maps — and maps of other surface properties, described in the series of papers released October 8 — Bennu’s boulders seem to come in two flavors: darker-colored rocks that are weaker and more porous and lighter-colored, denser rocks that are stronger and less porous. Even the denser rocks are much more porous and brittle than meteorites from similar asteroids that have been found on Earth. The least dense meteorites are about 15 percent porous; Bennu’s rocks seem to be between 30 and 50 percent porous, Rozitis and colleagues found.
    “This is exciting,” says DellaGiustina, a coauthor of the new papers. The spacecraft and its instruments might “encounter some boulders at the sample site that might otherwise be difficult to ingest,” she says, but “if they’re porous and weak, then they might just break down,” making them easier to collect.
    The lighter, denser rocks also appear to be shot through with veins of carbonate, which suggests that they were in the presence of flowing water at some point in their past (SN: 12/10/18). NASA chose Bennu as an asteroid to visit partly because it resembles carbonaceous chondrite meteorites, which scientists think are time capsules of the early solar system. Similar space rocks could have delivered water and organic materials to Earth billions of years ago.
    But Bennu’s more porous rocks appear to be unlike anything in scientists’ current assortment of meteorites, Rozitis says. “This is one of the cool things about OSIRIS-REx — it’s quite likely it will pick up new material that isn’t in our meteorite collection,” he says.

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    That’s believable, says meteor scientist Bill Cooke of NASA’s Marshall Space Flight Center in Huntsville, Ala. Observations of meteors have shown that low-density space rocks and dust burn up higher in Earth’s atmosphere than higher-density rocks.
    “The old conventional wisdom was that the low-density stuff was from comets, and the high-density stuff was from asteroids,” he says. But recent observations show that some of the low-density rocks come from the orbits of asteroids. “So it is very plausible that low-density stuff from Bennu … would ablate higher in the atmosphere and not have a chance to create meteorites at all.”
    If Bennu represents a missing piece in our understanding of the solar system’s history, studying that material in labs on Earth “will help us fill in an additional piece of the jigsaw,” Rozitis says. More

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    in Humans

    Rotten fish smell sweeter if you have a specific genetic mutation

    By Donna Lu
    Don’t mind the smell of rotten fish? A genetic mutation may be to blame
    Shutterstock / casanisa

    If you don’t find the smell of fish particularly off-putting, you may have an olfactory gene mutation that makes these odours seem less strong and disagreeable.
    Kári Stefánsson at Icelandic genomics firm deCODE Genetics and his colleagues have identified a gene, TAAR5, that affects how people perceive odours containing trimethylamine, a compound found in rotten and fermented fish.
    To study how genetics affects our sense of smell, the researchers asked 9122 Icelandic adults to smell six odours that were presented in … More

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    in Humans

    3000-year-old leather balls found in graves may be for ancient sport

    By Colin Barras
    The oldest balls found in Eurasia are leather sacks stuffed with leather strips or wool and hair
    Patrick Wertmann

    The first ball games in Eurasia may have been played 3000 years ago, according to a new analysis of three leather balls unearthed in an ancient cemetery in northern China. One of the men buried with a leather ball also sported the world’s earliest known pair of trousers, which he may have worn while playing.
    The Yanghai cemetery, which contains more than 500 graves, was in use between about 3200 and 1850 years ago. A few years ago, archaeologists … More