"Oxytocin is also kind of famous to scientists because it’s the hormone that’s released when people have an orgasm. The evolutionary thinking behind that is that humans have among the longest periods of raising their children of any species—their children remain in the nest until they’re fairly old. So there would be a survival advantage for a human child to have two parents, for the parents to stay together. Biologists argue that the purpose of the orgasm and the accompanying oxytocin is to create an emotional bond between two people so they’ll stay together. Well, it turns out there’s evidence that when people listen to music together or sing together, oxytocin is released then, too. So music forms a social bond in the same way orgasms may, which benefits us as a species."
-from Daniel Levitin, author of The World in Six Songs: How the Musical Brain Created Human Nature, as shared on The Daily Beast