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COGNITIVE “speed training” can reduce the risk of a dementia diagnosis by 25 per cent, according to results from the world’s first randomised controlled trial of any intervention against the condition. “There was a lot of scepticism about whether or not brain training interventions were beneficial and, to me, [our study] answers the question that they are,” says Marilyn Albert at Johns Hopkins University School of Medicine in Baltimore, Maryland. Brain training has generated controversy for years. In 2014, almost 70 scientists signed an open letter saying that there was no conclusive evidence that brain training produced changes that had real-world relevance or promoted brain health. Months later, another open letter signed by more than 100 scientists countered their arguments. “Speed training may build brain reserve – a kind of…

HUMANS were voyaging to remote islands off the north-west coast of Greenland 4500 years ago. This required them to cross over 50 kilometres of open water – one of the longest sea journeys made by Indigenous peoples in the Arctic. These intrepid seafarers were the first humans to ever reach these islands, says archaeologist John Darwent at the University of California, Davis, who wasn’t involved in the study. In 2019, Matthew Walls at the University of Calgary in Canada and his colleagues surveyed the Kitsissut Islands, also known as the Carey Islands, north-west of Greenland. The islands lie in the Pikialasorsuaq polynya, an area of open water surrounded by sea ice. Studies of marine sediments indicate that the polynya only formed about 4500 years ago. The researchers focused on the…

FIVE volcanoes on Jupiter’s moon Io erupted all at once in a cataclysm of lava. This means that they are probably all connected to the same underground magma network, which will help solve the mystery of Io’s insides. At the end of 2024, researchers monitoring Io via NASA’s Juno spacecraft saw an unusually enormous lava flow near its south pole. “There was this one gigantic eruption and lava flow, and that is what first caught our eye, but on second look, all these other hotspots lit up as well,” says Jani Radebaugh at Brigham Young University in Utah. “There’s so much magma that we can’t quite wrap our minds around it.” The erupted lava spanned an area of about 65,000 square kilometres and released more energy than any eruption previously spotted…

A DROP in air pollution during the covid-19 lockdowns changed the chemistry of the atmosphere, driving a surge in methane levels that has concerning implications for future global warming. Methane lasts only about a decade in the atmosphere but heats Earth far more than carbon dioxide. Its concentrations have been increasing since the 1980s, initially due mostly to venting and leaks during fossil fuel production. In the past two decades, these emissions have been compounded by a rise in microbes decomposing organic material in wetlands, agriculture and landfills. In 2020-2022, the increase in atmospheric methane surged from about 20 million tonnes per year to about 40 million tonnes per year, before returning to about 20 million in 2023. New research suggests the main reason is that covid-19 lockdowns reduced emissions…

A surge in methane (see main story) isn’t the only example of unintended consequences in Earth’s atmosphere. Trifluoroacetic acid (TFA), a potentially toxic “forever chemical”, has more than tripled in the global environment in two decades due to refrigerants introduced to help close the hole in the ozone layer. Chlorofluorocarbons (CFCs) were once found in refrigerators, aerosol sprays and other items. But they were banned in 1989 after it was discovered they were creating a hole in Earth’s protective ozone layer. They were largely substituted by hydrofluorocarbons (HFCs), which react with hydroxyl radicals in the atmosphere to form compounds including TFA. While HFCs are now being phased out, they are often replaced by hydrofluoroolefins (HFOs), which break down into TFA at a far higher rate. Based on long-running atmospheric measurements…

AN ENIGMATIC group of bacteria seems to thrive in the gut microbiomes of people without illness, hinting that they may be crucial to good health. More than 4600 species of bacteria are estimated to reside in our gut, interacting with each other and our bodies to influence everything from our immune system to our sleep, rate of ageing and risk of mental health conditions. Yet about two-thirds of these species are part of the “hidden microbiome”, most of which we haven’t managed to grow in a lab or even name. We only know they exist after spotting their genomes in the gut. “A burning question still remains: are these species just bystanders or relevant to human health?” says Alexandre Almeida at the University of Cambridge. To get an idea, Almeida…

EXERCISE is tremendously beneficial for our health in many ways, but it isn’t that effective when it comes to losing weight – and now we have the best evidence yet explaining why this is. People who start to exercise more burn extra calories. Yet they don’t lose nearly as much weight as would be expected based on the extra calories burned. Now, an analysis of 14 trials in people has revealed that our bodies compensate by burning less energy for other things. What’s more, this compensation effect is greater if people eat less as well as exercising more – and can completely cancel out the extra energy spent exercising. In other words, while eating less will result in weight loss, exercising while dieting may not result in any additional weight…

A QUANTUM battery has been built within a quantum computer, a first step in determining whether such batteries could play a role in powering future quantum technologies. Conventional batteries store energy because their components undergo electrochemical reactions, but quantum batteries rely on quantum bits, or qubits, which undergo changes in their quantum states. Some studies have shown that harnessing quantumness in this way can result in faster charging, but the practicality and usefulness of quantum batteries remain open questions. “Many future quantum technologies will need their quantum versions of batteries,” says Dian Tan at Hefei National Laboratory in China. “Many future quantum technologies will need their quantum versions of batteries” Tan and his colleagues built a battery using 12 qubits made from tiny superconducting circuits, each of which they could…

A LARGE and fast-melting glacier in West Antarctica has increased its flow speed dramatically since 2017. This may be a sign that the floating ice shelf in front of it is no longer helping to hold back the ice. Pine Island glacier is the fastest-flowing glacier in Antarctica and the largest contributor to sea-level rise of all Antarctic glaciers. It is a key part of the West Antarctic ice sheet, which holds enough ice to raise the global sea level by 5.3 metres if melted completely. The Pine Island ice shelf lies in front of the glacier and juts out over the ocean. It is thought to play a crucial role in holding back the inland ice, buttressing an amount of ice equivalent to 51 centimetres of sea-level rise. Sarah…