Chimpanzees are not as selfish as many human researchers of the past had believed. In a series of recent experiments using colored “tokens” two chimps placed in adjoining chambers could see one another through a screen. One chimpanzee had to pick either a “selfish” colored token or a “pro-social” token. If she made the pro-social choice, both chimpanzees would get a piece of banana wrapped in paper. Choosing the selfish option would reward only the chooser. Seven out of seven female chimps tested strongly preferred the pro-social option. Altruism, it seems, it not a human-only trait.