Abstract:Cooperation is ubiquitous in nature. Intuitively, the behavior is easy to be exploited by selfish cheaters unless a specific mechanism is at work. Cooperation has also been found in microbial world and intrigues many evolutionary biologists. Here, we provide a conceptual overview of several cooperation mechanisms based on microbial population models, including kin selection, Simpson’s paradox, repression of competition, evolutionary game theory and so on.