Hand preferences for bimanual feeding in 140 captive chimpanzees (Pan troglodytes): rearing and ontogenetic determinants.

Hand preference in bimanual feeding was assessed in 140 captive chimpanzees (Pan troglodytes). Bimanual feeding was defined as the active use of one hand for feeding with the opposite hand holding other food items. In terms of strength of hand preference, adults were more lateralized than sub-adults. Additionally, mother-reared chimpanzees were more lateralized than nursery-reared chimpanzees. The number of subjects with no hand preference was more prevalent in sub-adults compared with young and older adults. Of those subjects with a significant hand preference, a larger proportion exhibited a right-hand preference. These results are discussed in relation to previous reports of handedness and bimanual feeding in gorillas and bonobos.