HAND PREFERENCE FOR A BIMANUAL TASK IN TUFTED CAPUCHINS (CEBUS-APELLA) AND RHESUS MACAQUES (MACACA-MULATTA)

This research examined hand preference for a bimanual task in 45 tufte d capuchin (Cebus apella) and 55 rhesus macaque (Macaca mulatta) monke ys. Investigators presented subjects with plastic tubes lined with foo d and noted which hand the animals used to hold the tubes and which ha nd the animals used to remove the food. Several significant findings e merged from this investigation. First, rhesus macaques, but not tufted capuchins, exhibited a population-level bias toward use of the right hand (although the difference in direction of hand preference between species was not significant). Second, capuchins exhibited greater hand preference strength than did macaques. Third, among capuchins, but no t among macaques, hand preference strength was greater for adults than for immatures. Finally, both species used their index digit to remove food most frequently when compared with other digits. Findings of han d preference direction and strength in this study were compared with o ther findings noted for chimpanzees which performed a bimanual tube ta sk in a previous study. The authors conclude that using the same proce dure to compare hand preference across species represents a powerful r esearch tool that can lead to a more complete understanding of the evo lution and ontogenesis of primate handedness.