Adaptive exploration in chimpanzees

Exploration is an important strategy for reducing the uncertainty that pervades daily life. Yet the evolutionary roots of adaptive exploration are poorly understood. We harnessed and adapted the human decisions-from-experience paradigm to investigate exploration under uncertainty in chimpanzees. Subjects (N = 15; eight females) were simultaneously confronted with an uncertain option (with outcome variance) and a safe option (without outcome variance) and tested in both stable and changing environments. Results revealed that, as in human exploration, how and how much chimpanzees explore depends on environment and organism. One key environmental property is change: Chimpanzees explored more across trials in changing than in stable conditions. Consistent with the assumption of classic economic models that variance indicates risk, chimpanzees also explored more when they experienced variance in the options’ outcomes. Furthermore, in changing environments, chimpanzees focused on one option; in stable environments, a focus on one option and sequential exploration of both options were equally frequent. Individual risk and uncertainty preferences likewise impacted exploratory efforts, with risk- seeking chimpanzees exploring less, thus accepting more risks in their environment. These findings suggest that chimpanzees and humans share key similarities in the way they respond to risk and 16 uncertainty.