Philippa Kaur

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    in Humans

    Why people enjoy alcohol or are teetotal may come down to a hormone

    By Claire Ainsworth

    Matt Cardy/Getty Images

    LARS IGUM RASMUSSEN and his mates were going large. Donning their lederhosen, the three middle-aged men headed into Oktoberfest in Munich, Germany, the world’s biggest folk and beer festival. There, each proceeded to quaff an average of 7.5 litres of beer a day, for three days. It was a spectacular bender.
    Getting hammered wasn’t the main aim of the exercise, however: Rasmussen is health correspondent for Danish magazine Politiken and was writing a story exploring the physiological effects of binge drinking. To understand what was happening to him and his friends, he had enlisted the help of metabolic physiologist Filip Knop at the University of Copenhagen. While Rasmussen was interested in finding out what havoc excessive boozing wreaks on the bodies of middle-aged men, Knop had another motive for getting involved. He and his colleague Matt Gillum had been itching to test a new idea about people’s appetite for alcohol – but couldn’t, in good conscience, solicit anyone to partake in a binge of this magnitude. “It would give the ethics officer a heart attack,” says Gillum. Volunteers, however, were a different matter.
    What Knop and Gillum discovered is helping to build a picture of how our bodies control our boozing habits, from the amount we drink to when we stop. The research is homing in on a hormone that partly explains the huge variation in our social drinking habits: why some people are teetotal or can’t drink much, while others are lushes. It also points to the startling idea that our livers have more say in directing our behaviour than anyone imagined.
    Of course, people choose to … More

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    in Humans

    The Preserve review: The inner struggle to survive in a robot world

    How do humans feel living in a world where robots outperform them, asks The Preserve by Ariel S. Winter. Clare Wilson says it’s a great thought experiment

    Humans 9 December 2020
    By Clare Wilson
    How would we react if machines dominated the world?
    Donald Iain Smith/Getty Images

    The Preserve
    Ariel S. Winter
    Simon & Schuster
    WHEN AI that is truly sentient finally emerges, the big question is how humans will fare. Will machines try to hunt us to extinction, as in the Terminator films, or will their omnipotence mean life for humans can be the kind of extended party of Iain M. Banks’s Culture series?
    In Ariel S. Winter’s The Preserve, the robots have reached a stage somewhere in the middle. The book is set in the not-too-distant future, when human populations have dwindled … More

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    in Humans

    Can you ever know yourself? Whatever the answer, it is worth trying

    Gary Ellis Photography/Alamy
    “KNOW thyself.” The first of three maxims said to have been inscribed in the forecourt of the Temple of Apollo in Delphi sounds grand. What it actually means has been a matter of debate for millennia, and when it comes to knowing ourselves, modern science has made things deliciously more complex, too.
    How the physical substance of our bodies creates our sense of being a consistent entity, and what it means to have that sensation, is a long-standing puzzle. Debates about this relationship between matter and mind were meat and drink to the Ancient Greek philosophers, but … More

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    in Space & Astronomy

    Enormous X-ray bubbles balloon from the center of the Milky Way

    Two giant, mysterious bubbles spew from the Milky Way’s heart, and now it appears the bubbles may have doubles.
    Scientists have known for a decade that two bubbles of charged particles, or plasma, flank the plane of the Milky Way. Those structures, known as the Fermi bubbles after the telescope that detected them, are visible in high-energy light called gamma rays (SN: 11/9/10). But now, the eROSITA X-ray telescope has revealed larger bubbles, seen in X-rays. The X-ray bubbles extend about 45,000 light-years above and below the center of the galaxy, researchers report online December 9 in Nature.
    Previously, researchers had seen an X-ray arc above the galactic plane (SN: 7/8/20). But no such feature was evident below the plane of the galaxy. That lack of symmetry led some scientists to discount the possibility of X-ray bubbles. With the new results, “this argument now has fallen,” says study coauthor Andrea Merloni, an astronomer at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. The eROSITA data reveal a faint and previously unknown bubble below the galactic plane, and a matching bubble above. The gamma-ray bubbles are nested inside the X-ray bubbles, suggesting that the two features are connected, says Merloni.
    Studying the bubbles could help reveal violent events that may have taken place in the galaxy’s past. The supermassive black hole at the center of the Milky Way is currently fairly quiet, as far as black holes go. But a past feeding frenzy might have spewed its leftovers outward, forming the structures. Or the bubbles could have been the result of a period when many stars formed and exploded in the galaxy’s heart. Further study of the X-ray and gamma-ray bubbles could help reveal the cause. More

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    in Humans

    Ancient humans may have hibernated to survive brutal glacial winters

    By Colin Barras
    Living in darkness, or even hibernating, could have left ancient humans with bone lesions
    gorodenkoff/Getty Images

    Some of the ancient humans living in Europe half a million years ago had a remarkable strategy for dealing with winter: they hibernated. At least, that is the claim being made by two researchers. Others dispute the evidence – but ongoing research suggests that it might be possible to induce a hibernation-like state in modern humans.
    Sima de los Huesos – the “pit of bones” – lies in northern Spain and is one of the world’s most important sites for studying human evolution. Excavations at … More

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    in Humans

    Ancient rock art reveals life of the Amazon’s earliest inhabitants

    By Luke Taylor
    The rock art may be 12,500 years old
    Courtesy of Jose Iriarte

    An extensive collection of ancient rock art and archaeological remains found deep in the Colombian Amazon offers a rare glimpse into the lives of the earliest people to inhabit the region.
    The images and remains suggest that people lived in the northern Amazon at the same time as now-extinct mega-mammals. They also show that the ancient humans had a varied diet, indicating that they adapted quickly to their new environment.
    The as-yet unnamed site in the Serranía La Lindosa, a large, rocky outcrop in southern Colombia, was found by an international team of researchers investigating the Guaviare region. It is the earliest secure evidence of people in the Colombian Amazon, they say.

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    A wealth of Indigenous artwork has been documented across Guaviare, particularly in Chiribiquete National Park. The artwork documented at La Lindosa is new to science, and appears to be unknown even to local people, according to the researchers. It is remarkable in both its detail and its scale, the team says. The collage of images includes geometric patterns, handprints, people and animals. It stretches across approximately 5 kilometres of rock face, and could take decades to fully study.

    The archaeological team – co-led by Francisco Javier Aceituno at the University of Antioquia, Colombia – was thrilled to find depictions of what appear to be now-extinct megafauna alongside more familiar fish, birds and lizards still alive today.
    “We knew that megafauna was in the region and went extinct around 10 to 12,000 years before the present,” says José Iriarte at the University of Exeter, UK, and a member of the research team. If people were depicting them in their art, the humans must have been present in the region at least 12,500 years ago, he argues.
    Iriarte says it is “quite clear” that a palaeolama, an extinct stumpy-legged, long-necked camelid, is depicted. Other drawings have been tentatively identified as giant sloths due to their unique proportions, and mastodons – ancient relatives of elephants – due to their trunks.
    “The realism for South American standards is really impressive,” says Iriarte.

    Others are less sure.
    “The horses are clear,” says Hans ter Steege, an expert on Amazonian plant diversity at the Naturalis Biodiversity Center in the Netherlands, who wasn’t involved in the research. “But the palaeolama could be a poor representation of a deer to me.”
    Further study will be made of the artwork to gain more certainty of the depictions and their age, say the researchers.

    However, additional archaeological evidence makes clear that humans were present in the region 12,500 years ago. The researchers have excavated an area at the base of one section of rock face and uncovered evidence of ancient human activity in the form of processed animal bones. Some of the remains occur in layers of dirt containing charred palms that radiocarbon dating shows are about 12,500 years old. The 12,500-year-old layers also contain fragments of ochre similar to that used to draw the rock art.
    Establishing the presence of humans during this period — in which megafauna roamed the region and the climate was warming — is significant, says Aceituno.
    “The most important thing has been to obtain good radiocarbon dates to specify the early peopling of the area,” he says.
    It shows that humans shared the region with immense beasts, but also helps paint a picture of how their world would have looked.
    No megafauna remains have been found at the site, perhaps suggesting that humans didn’t hunt the animals or they were processed elsewhere. There were no remains of medium-sized animals like monkeys either, a staple food for Indigenous groups inhabiting the region today. “It could mean they had not developed blowgun technology at this stage to hunt prey in the treetops,” says Iriarte.
    Around half the remains were fish — including piranhas — but diets were broad. Reptiles like iguanas and snakes were consumed as well as rodents like paca and capybara.
    There is also evidence that various fruits were eaten. The diversity of animals and plants consumed suggests humans adapted quickly to the Amazon, says ter Steege.
    Journal reference: Quaternary International, DOI: 10.1016/j.quaint.2020.04.026
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    in Space & Astronomy

    Here are 10 of Arecibo’s coolest achievements

    The sun has set on the iconic Arecibo telescope.
    Since 1963, this behemoth radio telescope in Puerto Rico has observed everything from space rocks whizzing past Earth to mysterious blasts of radio waves from distant galaxies. But on December 1, the 900-metric-ton platform of scientific instruments above the dish came crashing down, demolishing the telescope and spelling the end of Arecibo’s observing days.
    Arecibo has made too many discoveries to include in a Top 10 list, so some of its greatest hits didn’t make the cut — like a strange class of stars that appear to turn on and off (SN: 1/6/17), and ingredients for life in a distant galaxy. But in honor of Arecibo’s 57-year tenure as one of the world’s premier observatories, here are 10 of the telescope’s coolest accomplishments, presented in roughly reverse order of coolness.
    10. Clocking the Crab Nebula pulsar
    Astronomers originally thought that apparently blinking stars called pulsars, discovered in 1967, might be pulsating white dwarf stars (SN: 4/27/68). But in 1968, Arecibo saw the pulsar at the center of the Crab Nebula flashing every 33 milliseconds — faster than white dwarfs can pulsate. (SN: 12/7/68). That discovery strengthened the idea that pulsars are actually rapidly spinning neutron stars, stellar corpses that sweep beams of radio waves around in space like celestial lighthouses (SN: 1/3/20).
    Arecibo observations of the frequency of radio flashes from the pulsar at the center of the Crab Nebula (red star in the middle) gave support to the idea that pulsars are rapidly spinning neutron stars.Optical: NASA, HST, ASU, J. Hester et al.; X-ray: NASA, CXC, ASU, J. Hester et al.
    9. Reborn pulsars
    In 1982, Arecibo clocked a pulsar, dubbed PSR 1937+21, flashing every 1.6 milliseconds, unseating the Crab Nebula neutron star as the fastest known pulsar (SN: 12/4/82). That find was puzzling at first because PSR 1937+21 is older than the Crab Nebula pulsar, and pulsars were thought to rotate more slowly with age.
    Then, astronomers realized that old pulsars can “spin-up” by siphoning mass from a companion star, and flash every one to 10 milliseconds. The NANOGrav project now uses such rapid-fire radio beacons as extremely precise cosmic clocks to search for the ripples in spacetime known as gravitational waves (SN: 2/11/16).
    Pulsars typically rotate more slowly as they age. But data from Arecibo showed that pulsars can ‘spin-up’ to rotate hundreds of times per second by siphoning material off a neighboring star (as seen in this artist’s impression; pulsar in blue).ESA, Francesco Ferraro/Bologna Astronomical Observatory
    8. Ice on Mercury
    Mercury seems like it would be an unlikely place to find water ice because the planet is so close to the sun. But Arecibo observations in the early 1990s hinted that ice lurked in permanently shadowed craters at Mercury’s poles (SN: 11/9/91). NASA’s MESSENGER spacecraft later confirmed those observations (SN: 11/30/12). Finding ice on Mercury raised the question of whether ice might exist in shadowed craters on the moon, too — and recent spacecraft observations indicate that it does (SN: 5/9/16).
    Images of Mercury taken by NASA’s MESSENGER spacecraft in 2011 and 2012 confirmed that hints of water ice (yellow) seen on the planet by Arecibo reside in shadowy regions at Mercury’s poles (north pole, shown; two craters labeled).NASA, JHUAPL, Carnegie Institution of Washington, Arecibo Observatory
    7. Unveiling Venus
    Venus is shrouded in a thick layer of clouds, but Arecibo’s radar beams could cut through that haze and bounce off of the rocky planet’s surface, allowing researchers to map the terrain. In the 1970s, Arecibo’s radar vision got the first large-scale views of Venus’ surface (SN: 11/3/79). Its radar images revealed evidence of past tectonic and volcanic activity on the planet, such as ridges and valleys (SN: 4/22/89) and ancient lava flows (SN: 9/18/76).

    Arecibo provided this early view of Venus’ surface using radar in 1971.D.B. Campbell/Cornell University
    Technological advances have allowed Arecibo to get crisper views of Venus. This 2015 image showcases the planet’s northern hemisphere.Smithsonian Institution, NASA GFSC, Arecibo Observatory, NAIC

    6. Mercury’s revolution
    In 1965, Arecibo radar measurements revealed that Mercury spins on its axis once every 59 days, rather than every 88 days (SN: 5/1/65). That observation cleared up a long-standing mystery about the planet’s temperature. If Mercury had turned on its axis once every 88 days, as previously thought, then the same side of the planet would always face the sun. That’s because it also takes 88 days for the planet to complete one orbit around the sun.
    As a result, that side would be much hotter than the planet’s dark side. The 59-day rotation better matched the observation that Mercury’s temperature is fairly even across its surface.
    Arecibo’s early radar observations measured the 59-day rotation rate of Mercury (shown in this false-color image of MESSENGER spacecraft data, which highlights chemical and mineralogical features on the planet’s surface).NASA, JHUAPL, Carnegie Institution of Washington
    5. Mapping asteroids
    Arecibo has cataloged the features of many near-Earth asteroids (SN: 5/7/10). In 1989, the observatory created a radar image of the asteroid 4769 Castalia, revealing the first double-lobed rock known in the solar system (SN: 11/25/89). Arecibo has since found space rocks orbiting each other in pairs (SN: 10/29/03) and trios (SN: 7/17/08).
    Other odd finds have included a space rock whose shadows made it look to Arecibo like a skull, and an asteroid with the improbable shape of a dog bone (SN: 7/24/01). Understanding the characteristics and motion of near-Earth asteroids helps determine which ones might pose a danger to Earth — and how they could be safely deflected.
    Arecibo radar images in 2000 revealed the strange dog bone shape of an asteroid named 216 Kleopatra (shown from multiple angles).WSU, NAIC, JPL/NASA
    4. Phoning E.T.
    The Arecibo Observatory broadcast the first radio message intended for an alien audience in November 1974 (SN: 11/23/74). That famous message was the most powerful signal ever sent from Earth, meant in part to demonstrate the capabilities of the observatory’s new high-power radio transmitter.
    The message, beamed toward a cluster of about 300,000 stars roughly 25,000 light-years away, consisted of 1,679 bits of information. That string of binary code detailed the chemical formulas for components of DNA, a stick figure sketch of a human, a schematic of the solar system and other scientific data. 

    3. Repeating radio blasts
    Fast radio bursts, or FRBs, are brief, brilliant blasts of radio waves with unknown origins. The first FRB known to give off multiple bursts was FRB 121102, which Arecibo first spotted in 2012 and again in 2015 (SN: 3/2/16). Finding a repeating FRB ruled out the possibility that these bursts were generated by one-off cataclysmic events, such as stellar collisions. And because FRB 121102 kept recurring, astronomers were able to trace it back to its home: a dwarf galaxy about 2.5 billion light-years away (SN: 1/4/17). This confirmed the decade-long suspicion that FRBs come from beyond the Milky Way.
    A repeating source of radio waves discovered by Arecibo (radio image, left) was the first fast radio burst traced back to its home galaxy. The burst originated in a dwarf galaxy about 2.5 billion light-years away (visible light image, right).H. Falcke/Nature 2017
    2. Making waves
    Gravitational waves were first directly detected in 2015 (SN: 2/11/16), but astronomers saw the first indirect evidence of ripples in spacetime decades ago. That evidence came from the first pulsar found orbiting another star, PSR 1913+16, first sighted by Arecibo in 1974 (SN: 10/19/74).
    By tracking the arrival time of radio bursts from that pulsar over several years, astronomers were able to map its orbit, and found that PSR 1913+16 was spiraling toward its companion. As the orbits of the two stars contract, the binary system loses energy at the rate that would be expected if they were whipping up gravitational waves (SN: 2/24/79). This indirect observation of gravitational waves won the 1993 Nobel Prize in physics (SN: 10/23/93).
    The first pulsar found orbiting another star, sighted by Arecibo in 1974, provided indirect evidence for the existence of ripples in spacetime called gravitational waves (illustrated).ESO, L. Calçada
    1. Pulsar planets
    The first planets discovered around another star were three small, rocky worlds orbiting the pulsar PSR B1257+12 (SN: 1/11/92). The find was somewhat serendipitous. In 1990, Arecibo was being repaired, and so it was stuck staring at one spot on the sky. During its observations, Earth’s rotation swept PSR B1257+12 across the telescope’s field of view. Small fluctuations in the arrival time of radio bursts from the pulsar indicated that the star was wobbling as a result of the gravitational tug of unseen planets (SN: 3/5/94).
    Thousands of exoplanets have since been discovered orbiting other stars, including sunlike stars (SN: 10/8/19). Recent exoplanet surveys, however, suggest that pulsar-orbiting planets are rare (SN: 9/3/15).
    The first worlds ever spotted beyond the solar system were three rocky planets (seen in this artist’s illustration) orbiting the pulsar PSR B1257+12.NASA, JPL-Caltech, R. Hurt/SSC More

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    in Space & Astronomy

    Why losing Arecibo is a big deal for astronomy

    Edgard Rivera-Valentín first visited the Arecibo Observatory as a little kid.
    “I definitely remember this feeling of just being awestruck,” Rivera-Valentín says. “Looking at this gigantic telescope … getting to hear about all this neat work that was being done … it definitely leaves an impression.” Important science was happening right in the backyard of Rivera-Valentín’s hometown of Arecibo, Puerto Rico — and someday, Rivera-Valentín wanted to be a part of it.
    As an adult, Rivera-Valentín returned to the observatory to work as a planetary scientist, using Arecibo to map the shapes and motions of potentially dangerous near-Earth asteroids. Now at the Lunar and Planetary Institute in Houston, Rivera-Valentín continues to use Arecibo data to study planetary surfaces. So the recent news that the Arecibo Observatory would shut down was “heartbreaking.”
    In August and November, two cables supporting a 900-metric-ton platform of scientific instruments above Arecibo’s dish unexpectedly broke. After assessing the damage, the National Science Foundation, which funds Arecibo, announced that the telescope could not be safely repaired and would be torn down (SN: 11/19/20). But before the telescope could be dismantled, the entire instrument platform crashed down into the dish on December 1.
    [embedded content]
    After suffering damage in recent months, the Arecibo Observatory radio telescope in Puerto Rico collapsed on December 1. Cables that suspended a platform of scientific instruments above the dish snapped, causing the platform to fall into the dish.
    For Puerto Rico, losing Arecibo is like New York losing the Empire State Building, or San Francisco losing the Golden Gate Bridge, Rivera-Valentín says — but with the added tragedy that Arecibo was not just a cultural and historic icon, but a prolific research facility.
    “The loss of Arecibo is a big loss for the community,” says Tony Beasley, director of the National Radio Astronomy Observatory in Charlottesville, Va. “The life cycle of Arecibo was really quite remarkable, and it did some amazing science.”
    The observatory’s radar maps of the moon and Mars, for example, helped NASA pick landing sites for the Apollo (SN: 5/1/65) and Viking missions (SN: 7/17/76). And observations of the asteroid Bennu helped NASA plan its OSIRIS-REx mission to snag a sample from the space rock (SN: 10/21/20). Arecibo views of Saturn’s moon Titan have revealed hydrocarbon lakes on its surface (SN: 10/1/03).
    Beyond the solar system, Arecibo has observed mysterious flashes of radio waves from deep space, called fast radio bursts (SN: 2/7/20), and the distribution of galaxies in the universe. Arecibo has also been used for decades in the search for extraterrestrial intelligence (SN: 11/7/92), and it beamed the first radio message to aliens into space in 1974 (SN: 11/23/74).
    In the wake of Arecibo’s collapse, the radio astronomy community is “going to have to look at what was going on at Arecibo and figure out how to replace as best we can some of those capabilities with other instruments,” Beasley says.
    In its 57-year lifetime, the huge radio telescope at the Arecibo Observatory in Puerto Rico (shown) made important discoveries in planetary science and astronomy.University of Central Florida
    But many of Arecibo’s capabilities can’t be easily replaced.
    “Arecibo was unique in several ways,” says Donald Campbell, an astronomer at Cornell University and a former director of the observatory. For starters, Arecibo was enormous. At 305 meters across — covering some 20 acres — Arecibo was the world’s largest radio dish from the time it was built in 1963 (SN: 11/23/63) until 2016, when China completed its Five-Hundred-Meter Aperture Spherical Telescope, or FAST. With such a huge dish to collect radio waves, Arecibo could see very faint objects and phenomena.
    That incredible sensitivity made Arecibo particularly good at detecting hard-to-spot objects such as rapidly spinning neutron stars called pulsars (SN: 1/3/20). As a pulsar rotates, it sweeps a beam of radio waves around in space like a lighthouse, which appears to Earth as a radio beacon flickering on and off.
    “Arecibo was the king” of spotting the fickle light of pulsars, Beasley says. “There’s not going to be a simple solution to regenerating that level of collecting area.” The next biggest radio dish in the United States is the 100-meter-wide Green Bank Telescope in West Virginia. Smaller telescopes may require several hours of observing a target to collect enough radio waves for analysis, whereas Arecibo took only minutes.
    Besides its mammoth size, Arecibo could also transmit radio waves. “Most radio astronomy telescopes do not have transmitters,” Campbell says. “They’re just receiving radio waves from space.” Radar transmitters allowed Arecibo to bounce radio waves off of gases in the atmosphere (SN: 1/31/70), or the surfaces of asteroids and planets. The reflected signals that came back contained information about the target such as size, shape and motion.

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    “The high-powered transmitters allowed what was the original primary purpose of the telescope — the study of the Earth’s ionosphere,” Campbell says. The U.S. military, which funded the construction of Arecibo, wanted to better understand Earth’s atmosphere to help develop missile defenses (SN: 2/10/68). But Arecibo’s radar transmitters “were also used to study solar system bodies — the planets, the moons, including our own moon,” Campbell says. “More recently, the emphasis has been on studying near-Earth asteroids” that could be on a collision course with Earth.
    Other big radio dishes, such as China’s FAST or the Green Bank Telescope, are not outfitted with radar transmitters. NASA’s Goldstone Deep Space Communications Complex in the Mojave Desert has a 70-meter dish with radar capabilities. But Goldstone “is used both as a military installation and also as part of the Deep Space Network that talks to spacecraft, so it doesn’t have a lot of time,” Rivera-Valentín says. “And it’s not as sensitive as Arecibo,” so it can’t see as many asteroids.
    Even at the time of its demise, the Arecibo Observatory still had “a bright scientific future,” says Joan Schmelz, an astronomer at the Universities Space Research Association in Mountain View, Calif., and a former deputy director of the observatory. “It wasn’t just resting on its laurels.” For instance, Arecibo was a key facility for the ongoing NANOGrav project, which uses observations of pulsars to search for ripples in spacetime kicked up by supermassive black holes (SN: 9/24/15).
    Arecibo’s observing days may be over, but that doesn’t mean data from the telescope won’t make any more contributions to science, Schmelz says. Some of radio astronomy’s most exciting discoveries have emerged from the reanalysis of old telescope data (SN: 7/25/14). “People will be continuing to analyze Arecibo data for some time,” she says, “and we’ll hopefully be seeing new scientific results as those data get analyzed and published.” More