It depends a great deal on how you define mutually beneficial, but yes, you could do this.
The easiest method would be to disable regular movement and require bots to move through "ties". Thus single bots would be unable to find food but multibots (several bots working together) could move about and find food.
However, if you're goal is to run a sim and have the bots mutate, you're going to find that altruism tends to be a trait selected against. There are some exceptions, but for the most part this is true. It's not explicitly done that way anywhere in the engine, it just seems that the rather featureless and static environment breeds this sort of selfishness.
We'll happily help you in your project if you spread the Darwinbots good word around