From ScienceDaily:

Researchers at the Yerkes National Primate Research Center, Emory University, have shown capuchin monkeys, just like humans, find giving to be a satisfying experience. This finding comes on the coattails of a recent imaging study in humans that documented activity in reward centers of the brain after humans gave to charity.

Empathy in seeing the pleasure of another’s fortune is thought to be the impetus for sharing, a trait this study shows transcends primate species.