Manual specialisation and tool use in captive chimpanzees (Pan troglodytes): the effect of unimanual and bimanual strategies on hand preference.

Hand preference for tool use was assessed in a sample of captive chimpanzees (Pan troglodytes). Whether the subjects solved the tool task using either a unimanual or coordinated bimanual strategy was manipulated in the chimpanzees. No population-level hand preference was found for tool use when unimanual strategies were used by the chimpanzees. However, a population-level right-hand bias was found when coordinated bimanual actions were required of the chimpanzees. A significant correlation was found in hand use for the two hand preference testing conditions. Neither sex nor rearing was found to significantly affect the direction or strength in hand preference. These results may explain discrepancies in hand preference reported in captive and wild chimpanzees with regard to tool use and other manual activities.