Chimpanzees form long-term memories for food locations after limited exposure

Remembering the location of fruiting trees for extended periods of time has been hypothesized to play a major role in the evolution of primate cognition. Such ability would be especially useful when paired with a fast learning mechanism capable of consolidating long-term memory after minimal exposure. We investigated whether chimpanzees (Pan troglodytes) can remember different food locations after minimal exposure (i.e., 1-2 trials) both after 24 hr and after 3-month. We released pairs of chimpanzees in their indoor enclosure (the enclosure of group A measured 430 m(2) and group B's measured 175 m(2) ) and tested them for four consecutive days (Baseline, Test, Retest, and Post-test). During the Test and Retest food was hidden in the same location whereas no food was hidden during the Baseline and Post-test days (control trials). Subjects were tested with four different locations and assessed for their retention after 24 hr and 3-month since the initial food discovery. Results revealed that chimpanzees accurately remembered the locations in which they found the food after one or two exposures to them, and both after 24 hr and a 3-month retention interval.