HAND PREFERENCES IN CHIMPANZEES (PAN-TROGLODYTES), BONOBOS (PAN-PANISCUS), AND ORANGUTANS (PONGO-PYGMAEUS) IN FOOD-REACHING AND OTHER DAILY ACTIVITIES

We observed 36 captive great apes [31 chimpanzees (Pan troglodytes), 2 bonobos (Pan paniscus), and 3 orangutans (Pongo pygmaeus)] reaching for items of food and engaging in other spontaneous behaviors. We consider circumstantial factors that could influence the preferred choice of one hand or the other. Most of the subjects (81%) showed a significant hand preference in food reaching that is consistent in directionality with the hand preferences that they showed during other spontaneous behaviors. The results show that the postural adjustment required when carrying out an action seems to influence directly the expression of manual laterality in individuals. Moreover, the results indicate the possible existence of a relationship between maturational factors and persistence in directionality of hand preferences.