Just because an organism doesn’t have a brain doesn’t mean it can’t think. Researchers gave single-celled slime molds a “food test”: In the easy exam, the funguslike organisms had to decide between eating 2%, 6%, or 10% concentrations of oatmeal in inedible agar—a fairly clear distinction. In the hard exam, they had to choose between oatmeal concentrations of 6%, 8%, or 10%—a more subtle difference. Molds that chose faster were five times more likely to choose the worst possible option. But they didn’t always respond like humans do. When comfortable, the organisms made quick decisions if the choice was easy and took their time if it was hard. But when the team starved the molds or shined harsh light on them, they chose faster when the choice was hard and slower when it was easy. This counterintuitive behavior may be related to risk, the researchers will report  online tomorrow in Proceedings of the Royal Society B. In the hard exam, the worst possible option (6%) wasn’t so bad, but in the easy exam, the worst option (2%) was dismal. So hungry molds had a lot to lose if they chose wrong.
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