Hand preference for quadrupedal and bipedal reaching in humans and rhe
sus macaques (Macaca mulatta) was examined. and the data were compared
with postural reaching data that have been reported for 8 other prima
te species. Population-level biases were found toward use of the right
hand for quadrupedal and bipedal reaching in humans and use of the le
ft hand for quadrupedal reaching in rhesus macaques. Rhesus macaques s
howed a significant shift toward greater use of the right hand for bip
edal vs. quadrupedal reaching. Comparisons with other species showed s
ignificant variance in the direction and strength of hand preference a
cross reaching postures. The study noted right-hand biases for bipedal
reaching in humans, great apes, and tufted capuchins and shifts towar
d greater use of the right hand for bipedal vs. quadrupedal reaching i
n great apes, tufted capuchins, and rhesus macaques. These results sug
gest that posture alters both the direction and strength of primate ha
nd preference and that bipedalism may have facilitated species-typical
right-handedness in humans.