The Evolution of Cooperation →

Humans routinely confront situations that require coordination between individuals, from mundane activities, such as planning where to go for dinner, to incredibly complicated activities, such as international agreements or transnational ventures (such as the International Space Station). Moreover, despite some failure, we frequently succeed in these situations. How did this ability arise, and what prevents success in those situations in which it breaks down? To understand how this capability has evolved, the CEBUS lab utilizes an explicitly comparative approach at both the species and individual levels.  

At the species level, we explore how individuals in many different species make these decisions, how these decisions differ across species, and what underlying mechanisms support successful cooperation. By determining how these species’ responses correlate with different aspects of the socio-ecology of each species, we can begin to make informed guesses about the function of behavior, or why it evolved. For instance, in one line of research we have discovered a correlation between species that respond negatively to inequity and the tendency to cooperate with non-kin outside of family groups. We also find that primates coordinate on economic games, but that Old World primates find better outcomes than do New World primates, indicating a split within the primate taxon.  

At the individual level, we use a similar approach to explore how differences in decision-making outcomes within a species correlate with aspects of an individual’s demographic characteristics, such as age, rank, sex, or personality, as well as social variables, such as individuals’ relationships. Finally, we are exploring how hormones such as oxytocin affect decision-making in primates. Our recent evidence indicates that oxytocin actually decreases food sharing in capuchin monkeys, so our main interest is in understanding what effect these hormones are really having on behavior, and how this varies across species. Such studies help us to better understanding the evolution of cooperation in primates, and hence provide insight into how cooperation works in humans.

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