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Oxytocin, the "love hormone" that builds mother-baby bonds and may help us feel more connected toward one another, can also make surly monkeys treat each other a little more kindly.

Administering the hormone nasally through a kid-sized nebulizer, like a gas mask, a Duke University research team has shown that it can make rhesus macaques pay more attention to each other and make choices that give another monkey a squirt of fruit juice, even when they don't get one themselves.