The prisoner’s dilemma is one of the best-known ideas in game theory. Game theory is a branch of mathematics that studies how individuals or organisms make decisions when they interact and compete for rewards. In this setup, two players can either cooperate or cheat. Cheating often gives a short-term gain, so both players usually cheat and end up worse off than if they had worked together.
Scientists have long used the prisoner’s dilemma to explain why selfishness seems to triumph in nature and human societies. A new study led by Rutgers physicist Alexandre Morozov offers a different view. Published in PNAS, the research shows that cooperation can arise on its own in simple conditions.
The power of memory and recognition
Morozov and collaborator Alexander Feigel discovered that the main requirement for cooperation is the ability to recognize previous interaction partners. If individuals remember who they dealt with and treat them the same way again, cooperation tends to develop naturally. This is as an emergent property, a behavior that appears from basic interactions without being directly programmed.
The researchers built mathematical models and ran computer simulations. These included groups of neural networks playing repeated games. They also developed a new version of Fisher’s fundamental theorem of natural selection, a key evolutionary principle that describes how traits spread in populations over generations.
The results suggest that even simple creatures such as microbes could develop cooperative behavior if they can distinguish one another through signals or traits. This removes the need for extra conditions like helping close relatives. Cooperation is the basis of complex life, from cells forming tissues to societies functioning. The model also shows patterns of stability followed by sudden changes, which appear in both biological evolution and human history.
Morozov hopes the work will lead to new studies on how cooperation evolves in living systems and perhaps offer fresh perspectives on human cooperation.