Ecological rationality: Convergent decision-making in apes and capuchins

Humans and other animals appear to defy many principles of economic 'rationality' when making decisions. Here, we use an ecological rationality framework to examine patterns of decision-making across species to illuminate the origins of these strategies. We argue that examples of convergent evolution-the independent emergence of similar traits in species facing similar environments-can provide a crucial test for evolutionary theories of decision-making. We first review theoretical work from evolutionary biology proposing that many economically-puzzling patterns of decision-making may be biologically adaptive when considering the environment in which they are made. We then focus on convergence in ecology, behavior, and cognition of apes and capuchin monkeys as an example of how to apply this ecological framework across species. We review evidence that wild chimpanzees and capuchins, despite being distantly related, both exploit ecological niches characterized by costly extractive foraging and risky hunting behaviors. We then synthesize empirical studies comparing these species' decision preferences. In fact, both capuchins and chimpanzees exhibit high tolerance for delays in inter-temporal choice tasks, as well as a preference for risky outcomes when making decisions under uncertainty. Moreover, these species exhibit convergent psychological mechanisms for choices, including emotional responses to decision outcomes and sensitivity to social context. Finally, we argue that identifying the evolutionary pressures driving the emergence of specific decision strategies can shed light into the adaptive nature of human economic preferences.