Three actions, two groups: Looking for the origin of primate manual lateralization.

Handedness is the most evident behavioral asymmetry in humans: to study nonhuman primate hand preference could be optimal to investigate the evolutionary origin of handedness in our species, even though behavioral asymmetries are widespread among vertebrates. This study investigated hand preferences in 32 Old World monkeys and 26 great apes during 3 spontaneous actions, assessing the effect of taxonomic group, sex and age on primate handedness. Data about foraging, locomotion, and manipulation were collected and 50 bouts per behavioral category per subject were recorded. A bias toward right-hand use for starting locomotion was reported in both Old World monkeys and great apes. Furthermore, in the great apes, a group-level right-hand preference for manipulation was found. Results suggest an important role of factors such as posture and task complexity in the evolution of primate manual lateralization. The effect of taxonomic group, sex, and age on the hand preference are also discussed. (PsycINFO Database Record