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    People living 100,000 years ago spent time collecting crystals

    By Alison George

    Calcite crystals collected by humans more than 100,000 years agoJayne Wilkins
    A cache of beautiful crystals collected 105,000 years ago in South Africa is shedding new light on the emergence of complex behaviours in our species.
    A team led by Jayne Wilkins at Griffith University, Australia, discovered 22 distinctively shaped white calcite crystals at a site in the Kalahari desert called Ga-Mohana Hill North Rockshelter. “They are little rhomboids, really visually striking,” says Wilkins.

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    These geometric crystals didn’t originate at the site and haven’t been modified, so seem to have been deliberately collected and brought to the rock shelter for ornamental purposes. “They don’t seem to have been used for everyday tasks,” she says.
    The collection of beautiful items seems like a normal thing for humans to do today, but this so-called symbolic behaviour only emerged around 100,000 years ago. “Collecting these kinds of pretty objects for non-utilitarian reasons could have its roots in symbolism and arts and culture,”  says Wilkins.

    Also found at the site were 42 fragments of burnt ostrich egg shell. The large egg shells may have been used by humans to store and transport water – offering more evidence of human innovation.
    These discoveries in the Kalahari, 600 kilometres from the sea, are challenging the prevailing assumption that the emergence of complex behaviours like symbolism and technological innovation emerged at the coast, where humans had access to seafood containing nutrients thought to support brain growth.
    Until now, the earliest evidence of symbolic behaviour was found at sites close to the sea, such as 100,000-year-old engraved ochre from Blombos cave and 60,000-year-old decorated ostrich egg shells from the Diepkloof rock shelter, both on the South African coast.
    “In the Kalahari, which is really far from the coast, we are seeing the same kinds of behaviours, at the same time,” says Wilkins.
    Journal reference: Nature, DOI: 10.1038/s41586-021-03419-0

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    Ancient Britons extracted salt from seawater more than 5500 years ago

    By Michael Marshall

    Coarse pottery that was used to help extract salt from seawaterS.J. Sherlock
    Stone Age Britons extracted salt from seawater using industrial-style processes more than 5500 years ago. The discovery means people in Great Britain were producing salt thousands of years earlier than thought, before the Bronze Age.The technology may have been brought by migrants arriving from mainland Europe.
    “It changes how we think about Neolithic society,” says Stephen Sherlock, an independent archaeologist based in Redcar, UK.

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    In mainland Europe, there is evidence of salt production from the heating of salty water as early as 6050 BC during the Neolithic: the last period of the Stone Age, before the invention of bronze. However, in Britain the earliest known evidence was from Brean Down in Somerset, where Bronze Age people were making salt around 1400 BC.
    Sherlock has been excavating for many years at Street House, near the town of Loftus in north-east England. The site was occupied from the Neolithic, about 5700 years ago, into the later Bronze Age and the Iron Age that followed, and as recently as the 7th century AD in the Anglo-Saxon period of English history.

    Geophysics revealed a buried structure about 200 metres from a Neolithic house, so Sherlock began digging.
    “It was sealed by about a metre of clay,” says Sherlock. Beneath that was a distinctive pit measuring 2.8 metres by 2 metres, with a narrow trench leading into it. Three areas of the pit had been intensely burned, leaving charcoal deposits: Sherlock argues these were hearths. A hazelnut shell in the charcoal layer was radiocarbon dated to between 3766 and 3647 BC.
    Similar structures are known from Iron Age deposits in Britain and are generally interpreted as “salterns” used for extracting salt from seawater. The water was placed in large ceramic pots, supported by stones over hot flames. The heat evaporated the water, leaving salt crystals. Sherlock found shards of pottery of a low quality characteristic of salt production.
    “I showed these finds to salt-making experts,” says Sherlock. “They said you’d expect to find that in the Iron Age.”
    Salt would have been the most valuable commodity in society, says Sherlock. It was hard to obtain and could be used to flavour or preserve food, for instance. “The people who controlled salt are going to be some of the richest.”
    Journal reference: Antiquity, DOI: 10.15184/aqy.2021.25
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    Uranium ‘snowflakes’ could set off thermonuclear explosions of dead stars

    Tiny crystals of uranium could set off massive explosions within a dead star, physicists propose, making for a cosmic version of a thermonuclear bomb.

    Expired stars called white dwarfs slowly cool as they age. In the process, heavy elements such as uranium begin to crystalize, forming “snowflakes” in the stars’ cores. If enough uranium clumps together — about the mass of a grain of sand — it could initiate a chain of nuclear fission reactions, or the splitting of atomic nuclei.

    Those reactions could raise temperatures within the star, setting off nuclear fusion — the merging of atomic nuclei — and generating an enormous explosion that destroys the star, two physicists calculate in a paper published March 29 in Physical Review Letters. The effect is akin to a hydrogen bomb, a powerful thermonuclear weapon in which fission reactions trigger fusion, says Matt Caplan of Illinois State University in Normal. The scenario is still hypothetical, Caplan admits — more research is needed to determine if uranium snowflakes could really spur a stellar detonation.

    White dwarfs are already known to be explosion-prone: They’re the source of blasts called type 1a supernovas. Typically, these explosions happen when a white dwarf pulls matter off a companion star (SN: 3/23/16). The researchers’ uranium snowflake proposal is an entirely new mechanism that might explain a small fraction of type 1a supernovas, without the need for another star. More

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    Here’s why humans chose particular groups of stars as constellations

    The Big Dipper’s stars make up a conspicuous landmark in the sky of the Northern Hemisphere. Even novice stargazers can easily pick out the shape, part of the Ursa Major constellation. Now, scientists have shown that three factors can explain why certain groups of stars form such recognizable patterns.

    To replicate how humans perceive the celestial sphere, a team of researchers considered how the eye might travel randomly across this night sky. Human eyes tend to move in discrete jumps, called saccades (SN: 10/31/11), from one point of interest to another. The team created a simulation that incorporated the distribution of lengths of those saccades, combined that with basic details of the night sky as seen from Earth — namely the apparent distances between neighboring stars and their brightnesses.

    The technique could reproduce individual constellations, such as Dorado, the dolphinfish. And when used to map the whole sky, the simulation generated groupings of stars that tended to align with the 88 modern constellations recognized by the International Astronomical Union, Sophia David and colleagues reported March 18 at an online meeting of the American Physical Society.

    “Ancient people from various cultures connected similar groupings of stars independently of each other,” said David, a high school student at Friends’ Central School in Wynnewood, Penn., who worked with network scientists at the University of Pennsylvania. “And this indicates that there are some fundamental aspects of human learning … that influence the ways in which we organize information.” More

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    Did you know? Triassic dinosaurs weren’t very big

    By Alexander McNamara
    and Matt Hambly

    Mohamad Haghani / Alamy
    The Triassic period started 252 million years ago after the Permian-Triassic extinction event, and in the 50 million years before the next extinction event, huge reptiles evolved and ruled the planet. One particularly fearsome species known as the rauisuchians stretched 9 metres from nose to tail with teeth like steak knives. However, the dinosaurs that existed at the time were much smaller creatures, many not much bigger than a cow. Though they were lacking in stature, some had some unusual features, like Tanystropheus, with a neck twice as long as its body.
    We can maintain relationships with only around 150 friends
    Clare Jackson / Alamy
    Although the number of friends on your Facebook profile might be a long way north of 500, there is a natural upper limit to the number of people you can maintain a stable social relationship with. This is known as Dunbar’s number, and it plays out in many more situations than you might realise. For example, historically it was the average size of English villages, the ideal size for church parishes, and the size of the basic military unit, the company.

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    There is also a correlation between primate brain size and the size of their social groups. Extrapolate this relationship to the size of a human brain and guess where that leads us? Yes,  around 150 social contacts.
    Mount Everest’s summit would be 2 kilometres underwater at the ocean’s deepest spot
    Alexmumu/Getty Images
    At its deepest point, in an area known as the Challenger Deep, the Mariana trench plunges to a depth of 10,984 metres (36,037 feet) below sea level. This is roughly the same distance below the waves that commercial airliners fly above them, and if Mount Everest were to start at the ocean’s lowest point, at 8849 metres it would still be more than 2000 metres below the surface.

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    The ‘USS Jellyfish’ emits strange radio waves from a distant galaxy cluster

    Something’s fishy in the southern constellation Phoenix.

    Strange radio emissions from a distant galaxy cluster take the shape of a gigantic jellyfish, complete with head and tentacles. Moreover, the cosmic jellyfish emits only the lowest radio frequencies and can’t be detected at higher frequencies. The unusual shape and radio spectrum tell a tale of intergalactic gas washing over galaxies and gently revving up electrons spewed out by gargantuan black holes long ago, researchers report in the March 10 Astrophysical Journal.

    Spanning 1.2 million light-years, the strange entity lies in Abell 2877, a cluster of galaxies 340 million light-years from Earth. Researchers have dubbed the object the USS Jellyfish, because of its ultra-steep spectrum, or USS, from low to high radio frequencies.

    “This is a source which is invisible to most of the radio telescopes that we have been using for the last 40 years,” says Melanie Johnston-Hollitt, an astrophysicist at Curtin University in Perth, Australia. “It holds the record for dropping off the fastest” with increasing radio frequency.

    Johnston-Hollitt’s colleague Torrance Hodgson, a graduate student at Curtin, discovered the USS Jellyfish while analyzing data from the Murchison Widefield Array, a complex of radio telescopes in Australia that detect low-frequency radio waves. These radio waves are more than a meter long and correspond to photons, particles of light, with the lowest energies. Remarkably, the USS Jellyfish is about 30 times brighter at 87.5 megahertz — a frequency similar to that of an FM radio station — than at 185.5 MHz.

    The Murchison Widefield Array consists of 4,096 radio antennas grouped into 256 “tiles” (one pictured) spanning several kilometers in a remote region of Western Australia.Pete Wheeler, ICRAR

    “That is quite spectacular,” says Reinout van Weeren, an astronomer at Leiden University in the Netherlands who was not involved with the work. “It is quite a neat result, because this is really extreme.”

    The USS Jellyfish bears no relation to previously discovered jellyfish galaxies. “This is absolutely enormous compared to those other things,” Johnston-Hollitt says. Indeed, jellyfish galaxies are a very different kettle of celestial fish. Although they also inhabit galaxy clusters, they are individual galaxies passing through hot gas in a cluster. The hot gas tears the galaxy’s own gas out of it, creating a wake of tentacles. The much larger USS Jellyfish, on the other hand, appears to have formed when intergalactic gas and electrons interacted.

    Hodgson and his colleagues note that two galaxies in the Abell 2877 cluster coincide with the brightest patches of radio waves in the USS Jellyfish’s head. These galaxies, the researchers say, probably have supermassive black holes at their centers. The team ran computer simulations and found that the black holes were probably accreting material some 2 billion years ago. As they did so, disks of hot gas formed around each of them, spewing huge jets of material into the surrounding galaxy cluster.

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    This ejected material had electrons that whirled around magnetic fields at nearly the speed of light, so the electrons emitted radio waves. Over time, though, the electrons lost energy, and the most energetic electrons, which had been emitting the highest radio frequencies, faded the most. Then a wave of gas sloshed through the entire cluster, reaccelerating the electrons around the two galaxies.

    “It’s a very gentle process,” Johnston-Hollitt says. “The electrons don’t get that much energy, which means they don’t light up at high frequencies.” Instead, the gentle gas wave caused electrons to emit radio waves with the lowest energies and frequencies, giving the USS Jellyfish the extreme spectrum it has today. More

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    British legal deeds were once written on sheepskin to prevent fraud

    By Karina Shah

    A deed written on sheepskin parchment from 1499David Lee
    Sheepskin was the most commonly used parchment for legal deeds over the past five centuries in Great Britain, even though it is quite fragile. This is most likely because fraud can be more easily detected on it than on vellum.
    Sean Doherty at the University of Exeter in the UK and his colleagues analysed 645 pages from 477 legal deeds concerning property in England, Scotland and Wales dating from 1499 to 1969.

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    They first cut a 2-square-millimetre sample of parchment from the edge of the documents. “We made sure to be well away from the text, any stamps and wax seals,” says Doherty.
    The team then chemically treated the animal skin to isolate the protein collagen, which is made up of a mix of sub-units called peptides. “Each animal has a different set of peptides that make up collagen – it is species variable,” says Doherty. This let the researchers work out what type of parchment each deed was written on.
    They found that 622 of the 645 pages were made from sheepskin, which was a surprise, as previous research suggested these types of documents were made with a variety of animal skin – most commonly vellum, which is made from calfskin.
    “We expected to see a wide range of animals, but they pretty much all turned out to be from sheep,” he says.

    Doherty and his team suspect that sheepskin was used for important deeds because it is difficult to alter without being noticed due to its high fat content.
    When animal skin is first processed, it is submerged into an alkaline solution of chalk. This draws out the fat and removes any hair, leaving behind the dermis layer of the skin which is then stretched into parchment.
    Sheepskin is between 30 to 50 per cent fat, compared to just 2 to 3 per cent in cattle and 3 to 10 per cent in goats. The removal of the fat causes sheepskin parchment to be very fragile. “The layers will detach because it has all these holes in it where the fat once was,” says Doherty.
    As a result, you can see a visible mark where text has been altered on sheepskin more easily than other animal skins, which is useful for important documents.
    “If someone intentionally tried to alter a word on a deed made of sheepskin, they would leave behind a telltale smudgy residue,” says Heather Wolfe at Folger Shakespeare Library in Washington DC, who wasn’t involved in the research.
    Journal reference: Heritage Science, DOI: 10.1186/s40494-021-00503-6

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    Bronze Age miners had cooked meals delivered to their workplace

    By Krista Charles

    Charred remains of millet, a cereal grain, found in the Eastern AlpsHeiss et al, 2021, PLOS ONE
    People working on mining sites in the Eastern Alps during the Bronze Age had cooked, bread-based meals delivered to them during the day.
    Andreas Heiss at the Austrian Academy of Sciences and his colleagues studied cooked food remains, including refined cereals and finely ground grains, obtained from Prigglitz-Gasteil in the Eastern Alps, a copper mine that was active between 1100 and 900 BC, during the Late Bronze Age.

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    These types of cereal-based food require preparation to make them edible, including separating grains from husks and then cooking them, but the team found no signs of this kind of work being done at the mine. There was also no evidence of harvesting nearby, suggesting the food must have come from elsewhere.

    “All the early stages from processing were entirely missing and this is usually a good indicator for a consumer habit that people did not produce themselves, but they received stuff that was already pre-processed,” says Heiss.
    Since wet ingredients like milk weren’t preserved, the researchers can’t say exactly which dishes the miners were being served, but they were likely to be bread based. Previous research has shown that these miners had pork delivered to them, but the new findings suggest that plant-based foods were a major part of their diet too.
    Lara González Carretero at the Museum of London Archaeology says this isn’t surprising. “It would be very time-consuming and there would be clear logistical issues for them to be able to cook their own meals in such a work setting.”
    Journal reference: PLOS One, DOI: 10.1371/journal.pone.0248287
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