Ecological rationality of intertemporal choice

Animals (humans included) are constantly making choices between smaller, sooner and larger, later rewards. Humans decide between a piece of cake or a slimmer waistline and between investing money in retirement or buying the latest electronic gadget. Other animals must choose between consuming the lower quality food that is available nearby or traveling for some time to higher quality food. My colleagues and explored whether the kinds of choices that a species faces in its natural environment shape its overall preferences. By comparing closely related species that differ in key aspects of their environment, we found that both temporal and spatial preferences match species' ecology for tamarin and marmoset monkeys (Stevens et al., 2005a, Stevens et al., 2005b) and temporal and risk preferences match species' ecology for chimpanzees and bonobos (Rosati et al., 2007, Heilbronner et al., 2008). Thus, we have demonstrated a number of cases in which a species' natural foraging environment shapes its overall preferences when compared to other species. In addition, we have examined how uncertainty influences intertemporal choice (Stevens et al. 2011a).