Chapter 7: The Evolution of Cooperation

Chapter Outline

1. Altruism

1. Behaviors that benefit others at a personal cost.
2. Behaviors such as grooming and alarm calling.
3. Natural selection can favor altruistic behaviors, despite the individual cost.

2. Mutualism

1. Behaviors that benefit both participants.
2. Only beneficial when all parties involved pull their own weight.

3. Kin Selection

1. Differential interaction (when altruists associate with other altruists) helps facilitate the evolution of altruism.

2. Hamilton’s rule states:
• Altruism is limited to kin.
• Closer kinship ties can lead to altruism that is costlier for the individual.
3. Kin recognition
• Phenotypic matching helps some primates recognize kin.
• Some mothers use contextual cues to recognize their infants.
• Infants also come to recognize their grandmothers and aunts when mothers associate with their mothers and sisters.
• Contextual cues can also help fathers recognize their offspring.
4. Kin biases
• Grooming is useful for hygienic and social reasons and occurs more often among kin than nonkin.
• When coalitions or alliances form to intervene in an attack, the members are usually close kin.
5. Parent–offspring conflict

4. Reciprocal Altruism

1. Altruism among individuals can evolve if altruistic behavior is balanced between partners.
2. For reciprocal altruism to work:
• Individuals must interact often.
• Individuals have to be able to keep track of acts.
• Individuals must provide support only to others who help them.

In This Chapter

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