seniorGame Theory
What is evolutionary stable strategy (ESS)?
Updated May 16, 2026
Short answer
An ESS is a strategy that cannot be invaded by any alternative strategy in a population.
Deep explanation
In evolutionary game theory, a strategy is stable if, once it dominates a population, no mutant strategy can outperform it. ESS refines Nash equilibrium by adding stability under perturbations.
Real-world example
Used in biology to model animal behavior survival strategies.
Common mistakes
- Confusing ESS with Nash equilibrium
- not all Nash equilibria are stable.
Follow-up questions
- What is invasion fitness?
- Is every ESS a Nash equilibrium?