| Evolutionarily stable strategy | |
|---|---|
| Solution concept in game theory | |
| Relationship | |
| Subset of | Nash equilibrium |
| Superset of | Stochastically stable equilibrium, Stable Strong Nash equilibrium |
| Intersects with | Subgame perfect equilibrium, Trembling hand perfect equilibrium, Perfect Bayesian equilibrium |
| Significance | |
| Proposed by | John Maynard Smith and George R. Price |
| Used for | Biological modeling and Evolutionary game theory |
| Example | Hawk-dove |
An evolutionarily stable strategy (ESS) is a strategy (or set of strategies) that is impermeable when adopted by a population in adaptation to a specific environment, that is to say it cannot be displaced by an alternative strategy (or set of strategies) which may be novel or initially rare. Introduced by John Maynard Smith and George R. Price in 1972/3,[1][2] it is an important concept in behavioural ecology, evolutionary psychology, mathematical game theory and economics, with applications in other fields such as anthropology, philosophy and political science.
In game-theoretical terms, an ESS is an equilibrium refinement of the Nash equilibrium, being a Nash equilibrium that is also "evolutionarily stable." Thus, once fixed in a population, natural selection alone is sufficient to prevent alternative (mutant) strategies from replacing it (although this does not preclude the possibility that a better strategy, or set of strategies, will emerge in response to selective pressures resulting from environmental change).