DELIBERATELY exposing people to the coronavirus behind covid-19 in a so-called challenge study has revealed why some people seem to be immune to catching the infection. As part of the first such work using the SARS-CoV-2 pathogen, which was carried out in 2021, a group of international researchers looked at outcomes for 16 people. All had no known health conditions and hadn’t tested positive for the virus or been vaccinated against it. To try to deliberately infect them, Sarah Teichmann at Cambridge Stem Cell Institute in the UK and her colleagues sprayed the original variant of SARS-CoV-2 up their noses. The researchers took nasal and blood samples before this and then six to seven times over the 28 days after. SARS-CoV-2 tests were done twice a day. Following exposure to the virus, the…

WIDEST REACH Mosquitos Mosquitos are responsible for almost half a million human deaths per year These insects pose an unusual threat to mankind for a creature that is, on average, only five millimetres (0.2 inches) long. Around the world, mosquitos are carriers of a staggering variety of diseases. There are about 3,500 known species of mosquito in existence, and in most cases the females are the only ones to feed on the blood of live hosts. They possess a minute but sharp proboscis, which can pierce even the tough skin of an elephant. Mosquitos preserved in amber dating back to the Cretaceous period have been discovered, but it’s thought these tiny menaces have been around for more than 200 million years, since they first diverged from other insects. Malaria accounts…

SCIENTISTS PLAN TO BRING ICONIC species back from extinction, which might have environmental benefits. Notably, the woolly mammoth could be a flagship species for conservation, highlighting the plight of endangered animals sharing its habitat. Mammoths reintroduced to the Arctic tundra would also work as ‘ecosystem engineers’, trampling trees and permafrost. This might recreate ice-age grassland, a surface that better reflects sunlight and traps carbon, helping to fight climate change. But is the resurrection of extinct species a reality, or simply sci-fi? How does de-extinction work? There are three methods. First, selective breeding or ‘back crossing’ – mating between members of a living species carrying traits of their ancestors, to increase the frequency of those ancestral traits within a population. That’s how cattle were bred to become ‘tauros’, a species that…

‘OVER THE PAST FEW YEARS, THE PERCEIVED LEVEL OF PSYCHOLOGICAL STRESS HAS RISEN DRAMATICALLY ACROSS THE GLOBE DUE TO A COMBINATION OF EVENTS INCLUDING THE LONG-LASTING COVID-19 PANDEMIC, CIVIL UNREST, ESCALATION OF POLITICAL INSTABILITY ACROSS THE GLOBE, AND CLIMATE CHANGE THAT HAS TRIGGERED MAJOR ENVIRONMENTAL AND ECONOMIC PERTURBATIONS. THE CONSEQUENCES OF THIS BROAD-SCALE INCREASE IN STRESS ARE ONLY BEGINNING TO BE APPRECIATED, BUT EVIDENCE SUGGESTS THAT WE ARE FACING A SECOND PANDEMIC OF MOOD AND ANXIETY DISORDERS, INCLUDING MAJOR DEPRESSION, ANXIETY, AND POSTTRAUMATIC STRESS DISORDER.’— HUDA AKIL & ERIC J. NESTLER “The neurobiology of stress: Vulnerability, resilience, and major depression.” PNAS, November 2023 MORE THAN a half century ago, a long-term study—one of the first sizable studies of its kind—led to a surprising discovery. In 1967, researchers in the United Kingdom…

IN MAY 1951, REPRESENTATIVE Peter F. Mack was in his southern Illinois district on what promised to be an unremarkable listening tour among his constituents. Amid the usual glad-handing and baby-kissing, Mack received a surprising challenge from his friend John W. Hobbs, an automobile parts manufacturer. Hobbs noted how scary things looked world-wide: Europe was still a mess after World War II, the Soviet Union had recently gotten the bomb, conflicts were raging in Korea and French Indochina, and anti-Western protests had begun in Iran. Conventional diplomacy had failed at the mighty task of bringing peace, Hobbs argued, in large part because U.S. diplomats rarely tried to communicate with ordinary citizens in other countries. “Our top brass just talks to the top brass of other countries,” Hobbs told Mack. “They never get…

Our experts examine the hottest new research CUTTING EDGE White dwarf stars are formed when all but the most massive stars run out of hydrogen fuel for their nuclear fusion and exit the main sequence. The star swells up as an enormously inflated red giant, puffing off its outer layers into a beautiful nebula of ionised gases. The core is all that remains of the original star and, as it can no longer support fusion, this ‘white dwarf’ slowly cools over billions of years. The majority of white dwarfs are composed of mostly carbon and oxygen, as these are the elements most red giants create towards the end of their lives. If the progenitor star was nearer eight times more massive than our Sun, however, there's an extra final step…

AMONG THE MOST FAMOUS OF ALL events in evolutionary history (if something that took 30 million years could be called an event) is when a lineage of fish-like animals emerged from the water onto the land, setting the scene for the radiation of amphibians, reptiles, birds and mammals. But over the following 370-odd million years, some of these terrestrial vertebrates performed spectacular U-turns: ichthyosaurs, plesiosaurs, sea turtles, penguins, whales, dolphins, manatees, dugongs, seals, sealions and walruses all returned to the sea. Who could tell from looking at a whale or a dolphin that they are descended from a group of terrestrial mammals that includes hippos and cattle? Or that manatees and dugongs are the closest living relatives of the elephants? The ancestry of seals and sealions – which, together with…

RESEARCHERS HAVE witnessed a new phenomenon in the brain as humans store memories, shedding light on the how the brain coordinates its many regions and billions of neurons. The team recorded participants' brain activity while they performed tasks that required memorising and recalling lists of words or letters. “Broadly, we found that waves tended to move from the back of the brain to the front while patients were putting something into their memory,” says Uma R. Mohan, a postdoctoral researcher at the National Institutes of Health in the US. “When patients were later searching to recall the same information, those waves moved in the opposite direction, from the front towards the back of the brain.” Brain waves are electrical oscillations that represent patterns of neural activity. Travelling waves spread out…

ENGINEERING A drone with a ‘rotating detonation rocket engine’ approached the speed of sound WORDS PETER RAY ALLISON Venus Aerospace has completed the inaugural test flight of a drone fitted with its rotating detonation rocket engine (RDRE), accelerating it to just under the speed of sound. The company wants to one day build superfast commercial jets using this new type of engine. In a 24 February test flight, the company flew the drone, which is 2.4 metres long and weighs 136 kilograms, to an altitude of 3,658 metres with an Aero L-29 Delfín plane before it was deployed and the RDRE was activated. The drone flew ten miles at Mach 0.9 – over 680 miles per hour – using 80 per cent of the RDRE’s available thrust. The flight proved the viability of…

BULLETIN For the first time, astronomers have observed the ‘plunge region’ surrounding a black hole, where orbiting material can no longer resist gravity's pull and plummets inward. The region is predicted by Einstein's theories, but has eluded the gaze of scientists until now. Most black holes pull gas from surrounding stars, surrounding themselves with an accretion disc. According to Einstein's theories of gravity, there is a point at which any particle straying too close to a black hole would no longer be able to continue in a circular path. Instead, it plunges rapidly inwards, towards the event horizon at close to the speed of light. While matter in this plunge region is doomed to fall inwards, light is still able to escape, meaning it should be possible to observe. Accretion…

If you were told that the Moon we see in our night sky isn't Earth's only one, you'd probably be a bit surprised. But some people have started to call the strange object that seems to orbit our planet, Earth's ‘second moon’ – and now scientists may have discovered where it came from. In fact, there are many moon-like objects around us in space, but only a handful of the over 200,000 ‘near-Earth asteroids’ (NEAs) have similar orbits to Earth. One of these, named 469219 Kamo‘oalewa, orbits the Sun, but moves in sync with our orbit so appears to orbit the Earth. This makes it our ‘quasi-moon’ or, to some, an ‘Apollo asteroid.’ Potentially as big as the Statue of Liberty, Kamo‘oalewa is between 40 and 100m (131–328 feet) across…

THE widespread claim that the ancient people of Easter Island underwent a societal collapse due to overexploitation of natural resources has been thrown into fresh doubt. Instead, a small and stable population lived sustainably for centuries before the arrival of Europeans, a new analysis of historical farming practices suggests. Famous for its towering stone statues, Easter Island – also known as Rapa Nui – lies in the Pacific Ocean and is thought to have been inhabited by Polynesians since around AD 1200. At that time, its 164 square kilometres were covered in palm forests, but these were destroyed quickly, probably by a combination of overharvesting and rats eating fruit and blooms. According to a popular narrative, the unsustainable use of resources led to runaway population growth and a subsequent collapse before Europeans…

Tigers There are currently 3,900 wild tigers estimated to be prowling the Earth. That’s 97 per cent fewer than existed a century ago. Of the nine tiger subspecies, three are extinct – the Caspian, Javanese and Balinese – and the South China tiger is known to be ‘functionally extinct’ with only a handful of individuals left in the wild, while the other five subspecies are endangered. So, in a bid to bring this beguiling big cat back from the brink, the governments of the world’s 13 tiger range countries made a plan. Through working with conservation experts, scientists, rangers and communities, they have pledged to double the tiger population by 2022 – the next Year of the Tiger in the Asian lunar calendar. These majestic creatures are apex predators and…

JUST STEPPED OUT FOR A WALK Astronauts train for many years for the chance to go to space, with no guarantee of actually flying, so being given a place on a mission to live on the International Space Station (ISS) for a few months is a dream come true. But some astronauts get to do even more – they wriggle into a spacesuit and go outside on an extravehicular activity (EVA), or spacewalk. This image, taken on 23 May 2017 during the 201st spacewalk of the ISS program, shows NASA astronaut Jack Fischer waving at his colleagues watching from inside the space station as he worked outside the US Destiny laboratory. Fischer was attaching antennae to the exterior of the ISS during an unplanned EVA to repair and replace a…

UNTIL THE middle of the 19th century, surgery was performed with no anesthesia. You don’t need a fertile imagination to realize how excruciating the experience was for patients. Nor did the surgeons who administered this particular type of torment take it lightly. In The Worst of Evils: The Fight Against Pain, scientist and author Thomas Dormandy describes how 19thcentury surgeon and medical pioneer Sir James Paget recalled those gruesome days before anesthesia in his memoirs: “They had been the worst nightmares. I can remember them still. Even now, they sometimes rouse me from my sleep. I wake drenched in sweat.” Paget wasn’t the only one who was disturbed by the experience. Charles Darwin dropped out of medical school at least partly because he didn’t have the stomach for pre-anesthesia surgery. These days,…

FOR a long time, it looked as if the Soviet Union would beat the US towards the ultimate victory in the space race. But when the Soviet Union’s N1-L3 test vehicle toppled backwards in flames onto its launch pad, it become clear that the US would make it to the moon first. On 21 July 1969, just five days after taking off from Cape Canaveral in Florida, the Apollo 11 crew touched down on the moon. Following Neil Armstrong onto the lunar plain of the “Sea of Tranquility” was Buzz Aldrin, the second man to walk on the moon. Completing the mission’s crew of three was Michael Collins, who remained alone circling the moon in the orbiter that had dispatched the landing module, codenamed Eagle. But how did the crew…

There seems to be a lot of overlap between supposedly different types of anomalous phenomena. For example, starting in the mid-1960s, and continuing until about 1977, the Warminster area of Wiltshire generated numerous reports of UFO sightings, although claims about strange phenomena thereabouts weren’t confined to aerial manifestations.1 There were, for instance, reports about people hearing mysterious footsteps, and of vehicles colliding with human-like figures, but with no casualties being found. However, the Warminster case is controversial, with some commentators suggesting that prosaic factors, such as the misinterpretation of ordinary aerial objects and sensationalist news reporting can explain what allegedly occurred (not to mention hoaxing; see FT331:40-47). But if a substantial number of the reports were true, the locality may have been, at least temporarily, a hot spot for weird…