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Female red deer with big brains have it all

A big brain might seem like a smart thing to have. But lab studies of various rodents and primates have shown that although species with larger brains live longer, they have fewer offspring—which, in the game of life, is not so smart. Now, a new study of wild red deer (pictured) in the United Kingdom challenges this finding. Scientists measured the interior volume of 1314 red deer skulls of both sexes recovered from individuals in a population that has been studied for more than 40 years. There wasn’t any association between a female’s brain size and how often she gave birth, the scientists report today in Royal Society Open Science. But female red deer with larger brains lived longer and had more surviving offspring—and they passed their big brain trait to their kids, indicating that it’s beneficial. The male deer told a different story. The scientists did not find any association between the size of their brains and longevity, fecundity, or lifetime breeding success—perhaps because males grow antlers, which limits the size of their skulls.