the biological problem: in the hamadryas baboon, males are larger than females. baboons live in groups with one male and several females. in an experiment, two males, a and b, were placed in an enclosure. a female was introduced, and a quickly claimed her. when b was released, he avoided conflict. kummer showed that b accepted a's claim, not because he was weaker, but because he recognized a's dominance. when the roles were reversed, b claimed the female, and a did not challenge. this shows that baboons can settle disputes without escalation. escalated contests do occur, such as when a male is removed and another takes over his females. when the first male returns, a fight ensues. these behaviors are explained by evolutionary theory, where strategies that increase fitness are favored by natural selection. however, the best strategy depends on the opponent's actions. escalation is only beneficial if the opponent retreats. in these lectures, the focus is on strategies expected to evolve. learning and kin selection are ignored, as contestants are assumed to have no prior knowledge and are genetically unrelated. this is important because harming a sibling reduces inclusive fitness. the concept of an evolutionarily stable strategy (ess) is introduced, which is a strategy that, if adopted by a population, cannot be invaded by any alternative strategy. an ess is a strategy that, when played against others playing the same strategy, yields a higher payoff than any alternative strategy. this concept helps explain the evolution of animal behavior.the biological problem: in the hamadryas baboon, males are larger than females. baboons live in groups with one male and several females. in an experiment, two males, a and b, were placed in an enclosure. a female was introduced, and a quickly claimed her. when b was released, he avoided conflict. kummer showed that b accepted a's claim, not because he was weaker, but because he recognized a's dominance. when the roles were reversed, b claimed the female, and a did not challenge. this shows that baboons can settle disputes without escalation. escalated contests do occur, such as when a male is removed and another takes over his females. when the first male returns, a fight ensues. these behaviors are explained by evolutionary theory, where strategies that increase fitness are favored by natural selection. however, the best strategy depends on the opponent's actions. escalation is only beneficial if the opponent retreats. in these lectures, the focus is on strategies expected to evolve. learning and kin selection are ignored, as contestants are assumed to have no prior knowledge and are genetically unrelated. this is important because harming a sibling reduces inclusive fitness. the concept of an evolutionarily stable strategy (ess) is introduced, which is a strategy that, if adopted by a population, cannot be invaded by any alternative strategy. an ess is a strategy that, when played against others playing the same strategy, yields a higher payoff than any alternative strategy. this concept helps explain the evolution of animal behavior.