7.4 Prisoner’s dilemma

Animals are nice to non-kin (like friends)

• Reciprocal altruism (Trivers): if you scratch my back, I will scratch yours
  • Problem of cheating: the reciprocal altruism appears to be untenable.
• Reciprocal altruism can evolves if animals can punish theaters. They need to 1) recognize cheaters 2) remember them 3) be motivated to punish
• Prisoners dilemma
  • no solution for one game
  • what if you can play the game over and over? Tit-for-tat
    • The first time cooperate
    • After that, do on each trial what the other did on the previous trial
• We feel gratitude and liking for people who cooperate with us. This motivates us to be nice to them in the future.
• We feel anger and distrust toward those who betray us. This motivates us to betray or avoid them in the future.
• We feel guilt when we betray someone who cooperates with us. This motivates us to behave better in the future.