Acquired preferences for piquant foods by chimpanzees.

Humans frequently develop likings for innately unpalatable substances, while this occurs very rarely in non-humans. In this study, we establish a preference for crackers seasoned with chili pepper in two domesticated chimpanzees. Chimps were offered a series of increasingly piquant crackers by their caretaker, and gradually came to prefer these crackers to unseasoned crackers. The preferences were stable over months, and generalized to a different piquant cracker. Available evidence suggests that these are acquired likes rather than preferences maintained because of positive consequences that follow ingestion. We note that all existing instances of acquired likings for innately aversive foods in animals (including some informal results from dogs presented in this paper) involve animals with a close personal relationship with humans, suggesting an important role for social-affective factors in the reversal of innate aversions.