Laterality in the gestural communication of wild chimpanzees

Abstract

We examined hand preference in the intentional gestural communication of wild chimpanzees in the Budongo forest, Uganda. Individuals showed some tendency to be lateralized, although less than has been reported for begging and pointing gestures in captivity; on average, their absolute bias was around 0.25 (where 1.0 represents complete right- or left-hand use and 0.0 represents no bias). Lateralization was incomplete even in individuals with major manual disabilities. Where individuals had a stronger preference, this was more often toward the right hand; moreover, as age increased, the direction (but not the extent) of hand preference shifted toward the right. While the gestural repertoire as a whole was largely employed ambilateraly, object-manipulation gestures showed a strong right-hand bias.