TIT FOR TAT in sticklebacks and the evolution of cooperation

Nature. 1987 Jan 29-Feb 4;325(6103):433-5. doi: 10.1038/325433a0.


The problems of achieving mutual cooperation can be formalized in a game called the Prisoner's Dilemma in which selfish defection is always more rewarding than cooperation. If the two protagonists have a certain minimum probability of meeting again a strategy called TIT FOR TAT is very successful. In TIT FOR TAT the player cooperates on the first move and thereafter does whatever the opponent did on the previous move. I have studied the behaviour of fish when confronting a potential predator, because conflicts can arise within pairs of fish in these circumstances which I argue resemble a series of games of Prisoner's Dilemma. Using a system of mirrors, single three-spined sticklebacks (Gasterosteus aculeatus) approaching a live predator were provided with either a simulated cooperating companion or a simulated defecting one. In both cases the test fish behaved according to TIT FOR TAT supporting the hypothesis that cooperation can evolve among egoists.

MeSH terms

  • Animals
  • Biological Evolution*
  • Fishes / physiology*
  • Game Theory*
  • Models, Psychological