Jeremy Van Cleve (Omidyar Fellow, Santa Fe Institute)
Abstract. Understanding the evolution of complex social behaviors such as cooperation is one of the most important challenges in evolutionary biology and the social sciences. An old and unresolved controversy regarding social behaviors is whether and when natural selection can lead to behaviors that maximize fitness at the level of a social group, but are costly at the individual level. Such behaviors are known to be important in evolutionary transitions from simpler to more complex forms of life. In this talk, we will show that tools from behavioral economics and quantitative genetics can be combined to give unique insights into this question. We first show how social preferences in behavioral economics can be used to explain how cooperation evolves in simple biological situations and how such preferences can form the basis of emotions such as empathy. We then demonstrate how social preferences can evolve in a structured population where individuals can be related due to common ancestry. In such a population, cooperation can evolve both due to the behavioral responses generated by social preferences and due to common genetic interests. We show that behavioral responses and genetic relatedness interact synergistically so that behaviors that maximize group benefit can evolve. Thus, the interplay between proximate mechanisms of behavior, such as social preferences, and genetic relatedness is crucial to determining the conditions that allow the evolution of complex forms of life.