If you want to get your oxytocin flowing, there’s no better place to do it than in the bright, sunny play space on the campus of Duke University where Brian Hare and Vanessa Woods spend their days. Oxytocin, nicknamed the cuddle chemical, is a hormone produced by the hypothalamus that gives rise to feelings of love, warmth, altruism, and caring; it spikes in the bloodstreams of lovers, friends, and, especially, new mothers and their babies—and Hare and Woods fairly traffic in the stuff.