Almost all mammals avoid eating chili peppers and other “hot” foods, because of the pain they induce. But not the tree shrew, according to a study publishing July 12 in the open-access journal PLOS Biology by Yalan Han of the Kunming Institute of Zoology in China, and colleagues. The researchers found that this close relative of primates is unaffected by the active ingredient in chili peppers due to a subtle mutation in the receptor that detects it. They speculate that this is an evolutionary adaptation to enable tree shrews to cope with a peppery plant that makes up part of their diet.