Maynard Smith (1984)

A Qualitative Example:

Payoff To When Against
  “HAWK” “DOVE”
“HAWK”  – 2 +2
“DOVE”  0 +1
  • These are not hawks and doves but 2 animals of the same species competing with different strategies.
  • “Hawk” is aggressive and dangerous
  • “Dove” is unagressive but safe.
  • theory is about an “Evolutionarily Stable Strategy” (ESS) which applies to a population.
“Hawk” is not stable, because a mutant dove does better against a hawk (assuming the payoffs here) than another hawk.

Similarly “Dove” is not itself an ESS because a mutant hawk would have the advantage in a population of doves.
But —

  1. If all animals are either one or the other the population would evolve to 0.33 hawks and 0.67 doves.
  2. Or a “mixed” ESS is stable if all animals are hawks a third of the time and doves for the other two third.
  3. This could happen if animals learn from experienced pay-offs to be hawkish a third of the time.
  4. Learning is necessary for reciprocal altruism in social groups. (e.g. the “tit-for-tat” model).