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18 | NewScientist | 6 August 2011 GOTHAM CITY famously relies on a bat signal to call for help. Now we know that a Cuban flower does too. The rainforest vine Marcgravia evenia grows an unusual bowl- shaped leaf above each ring of flowers and nectaries. The plant’s other leaves are much flatter. Ralph Simon of the University of Ulm, Germany, suspected the bowl-leaf is an adaptation to draw pollinating bats, which use echolocation to navigate the forest. So he played sounds at the plant and analysed the resulting echoes. Ordinary leaves produced a strong echo when face-on to the sound source, but the signal strength dropped – and its acoustic signature changed – as the source shifted position in front of the leaf. The signal from a bowl-leaf, however, retained its strength and character wherever Neanderthals got lost in the crowds WAS it good old-fashioned competition, not interbreeding, that led to the demise of the European Neanderthals? Recent genetic evidence that our extinct cousins interbred with modern humans has seen a spate of interbreeding hypotheses to account for their demise. But Paul Mellars and Jennifer French at the University of Cambridge point out there is no evidence for interbreeding when European Neanderthals disappeared. The duo says that the archaeological record does, however, show that the number and size of occupied sites increased enough when the first modern humans reached Europe to suggest the population grew tenfold. They say it was the weight of numbers of modern humans – sustained by better technology – that pushed Neanderthals to extinction (Science, DOI: 10.1126/ science.1206930). Brain to car: “Apply the brakes now, please” TALK about cutting out the middleman. A mind-reading device that taps into a driver’s brain can recognise and act on the brain signals to stop the car precious milliseconds before the signals become leg movements. Some cars carry systems to detect traffic danger, and will then stop the vehicle the moment the driver touches the brake. Stefan Haufe from the Berlin Institute of Technology in Germany says plugging into the driver’s thoughts could make response times even faster. With colleagues, he wired 18 volunteers to an EEG headset, a non-invasive way to measure brain activity, STEFAN FALKE/LAIF/CAMERAPRESS IN BRIEF Cuban flowers rely on bat signal the sound source was placed. Simon reckons the better echo from the bowl-leaf helps bats find the flowers. In experiments, he found that nectar-feeding bats (Glossophaga soricina) could find an artificial nectary twice as fast with a replica of a bowl-leaf – rather than a flat leaf – above it (Science, DOI: 10.1126/science.1204210). The bowl-leaves are less efficient at photosynthesis, but Simon says that the benefits of attracting bats outweigh this cost. and asked them to drive at 100 kilometres per hour in a car simulator, closely following the car in front. The EEG measured patterns of brain activity as drivers were forced to brake suddenly. It recorded three distinct patterns, which the team were able to use to detect the intention to brake before the driver moved, says Benjamin Blankertz, also at TU Berlin, who co-led the study. Sensors on the drivers’ legs to monitor muscle tension provided another way to confirm the intention to brake. The system reliably triggered the braking system 130 milliseconds sooner than waiting for the driver to touch the pedal. At 100 km/h that reduces the stopping distance by the length of a small car – potentially enough to prevent an accident ( Journal of Neural Engineering, DOI: 10.1088/1741-2560/8/5/056001). IT’S the tiniest drop of water possible. The isolation of a single water molecule inside a carbon cage could allow the life-giving stuff to be studied in a new way. Kei Kurotobi and Yasujiro Murata of Kyoto University in Japan made a pore in a carbon buckyball. Oxygen atoms ringing the pore bonded to one water molecule, which then entered the spherical cage under high temperature and pressure (Science, DOI: 10.1126/science.1206376). Researchers can now study how water behaves when stripped of the hydrogen bonds that normally govern its properties, as well as the molecule’s two different “spin” states, which cannot be separated when water molecules are en masse. Water in solitary confinement
