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14 | NewScientist | 20 July 2013 THINK you’re all grown up? Placing yourself in the virtual body of a 4-year-old will send you right back to your halcyon days. Mel Slater of the University of Barcelona in Spain and colleagues put 30 people in a virtual reality (VR) environment in the body of a 4-year-old child or a scaled-down adult the same height as the child. The virtual body, which moved in sync with movements of the real body, could be viewed from a first-person perspective and in a mirror in the VR environment. All of the people judged virtual objects to be bigger than they actually were, but the people embodying a child made worse guesses (PNAS, DOI: 10.1073/ pnas.1306779110). It has been argued that we reference our own body size to judge the size of objects. Now First exoplanet hue is a lovely dark blue PLANET HD 189733b is blue, and there’s nothing I can do. It doesn’t scan like David Bowie’s original lyric, about Earth, but this alternative is accurate now that an exoplanet’s colour has been measured for the first time. A gas giant, HD 189733b’s surface is a roasting 844 °C. At 63 light years away, it is too distant for astronomers to separate its light from that of its host star. But using the Hubble Space Telescope, Frédéric Pont of the University of Exeter, UK, and colleagues found a large dip in blue wavelengths when HD 189733b passed behind its star – suggesting that it reflects mainly blue light (Astrophysical Journal Letters, doi.org/m63). Earth appears as a pale blue dot from space, due to light scattering off the atmosphere, but HD 189733b is darker. Clouds of glassy silica dust make it reflective, while sodium atoms, which absorb red and green, colour it dark blue. Dam! Beavers have been busy sequestering carbon BEAVERS aren’t going to save the world – but they are doing their bit for carbon capture and storage. The dams they build, and the wetlands produced as a result, lock away a surprising amount of carbon. “Beavers offer a mechanism of carbon storage,” says Ellen Wohl of Colorado State University in Fort Collins. Beaver dams cause water to breach riverbanks, creating areas of wetland known as beaver meadows, which contain large amounts of sediment and organic material. If the dam breaks the meadows dry out, exposing the material to the air and releasing some ROBERT MCGOUEY/WILDLIFE/ALAMY IN BRIEF Being a child ruins your judgement Slater’s team has shown that higher-level cognitive processes, perhaps memory of childhood, may also be at work. The researchers say that brain imaging studies would help them to understand the reorganisation that occurs when assimilating a new body. The motivation springs from a project looking at how to embody people in child-sized robots. “We thought we ought to look at the consequences of that first,” says Slater. of the carbon stored within them. Using previously published carbon-content values, Wohl estimated the total organic content from dried-up beaver meadows in 27 drainage basins in Rocky Mountain National Park, and found it accounted for 8 per cent of the carbon in the landscape. She estimated that when the meadows were flooded they may have sequestered as much as 23 per cent of the carbon (Geophysical Research Letters, doi.org/m7r). Beaver numbers have been declining in the park since the 1940s. Wohl says there were once between 60 and 400 million beavers in North America – a number that would have had a significant effect on the ecosystem. There are now thought to be 6 to 12 million, and the park service is working towards reintroduction. IF YOU’RE being chased by a bear, having a friend alongside is a good idea: trip them up, and you can flee. You’re probably too decent to do that, but a little South American fish, the two-spot astyanax, has no such qualms. These fish sometimes swim into hydroelectric plants, damaging machinery. While seeking ways to deter them, Robert Young of the University of Salford, UK, observed that when a predator confronts a group of astyanax, they bite one of their number – making it a tempting target (Animal Behaviour, doi.org/m6j). Young reckons the fish adopt this strategy because they live in small groups, giving individuals an incentive to be selfish. Fish throw friends to the wolves
