Lecture | Sarah Brosnan | Comparative Decision Making in Non-Human Primates
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 multi-national agreements. How did this ability arise, and what prevents success in those situations in which it breaks down? To understand how this capability evolved across the primates, my lab uses the methodology of experimental economics. This is an ideal mechanism for the comparative approach as it is a well-developed methodology for distilling complex decision-making in to a series of simple choices, allowing these decisions to be compared across species and contexts using identical methodologies. We have investigated coordination in New World monkeys, Old World monkeys, and great apes, including both chimpanzees and humans. We find that there are remarkable continuities of outcome across the primates, including humans, however there are also important differences in how each species reaches these outcomes. For example, while humans and other primates can find the same coordinated outcome, our research indicates that they are using different cognitive mechanisms to do so. Additionally, in many primates, including humans, cooperation breaks down under conditions of inequity. However, only humans and chimpanzees seem to be able to rectify inequity, presumably avoiding this breakdown and thereby maintaining a successful cooperative partnership. This ability is undoubtedly the foundation of the much more complex sense of fairness that evolved uniquely in humans. By carefully considering both the similarities and differences among species, we can better understand how cooperative decision-making emerged in the primates, and how each species relates to the others.