Mutualism in nature describes the relationship of two different species interacting to provide both with a benefit. Pollination is the most well-known example: birds and insects get nectar from flowers in exchange for carrying the plants' pollen to fertilize other individuals. In some mutualist combinations, the opportunity is present for one species to take advantage of the other. Take for example, the fig wasp: It pollinates the fig tree in exchange for seeds. Nevertheless, it never takes more seeds than it needs. Science is reporting on a fascinating new study which finally explains why. Turns out there is a second wasp involved who keeps the fig wasp in check.