Left Handedness in a Captive bonobo Group

Handedness in great apes is related to laterality and cognitive development. Previous studies report a right-handed bias in 9 ape studies. This study observed a group of 16 captive bonobos (Pan paniscus) at the Columbus zoo that was presented with an artificial, baited termite mound. Data was collected from narrated video tapes taken June 29, 2011 – August 31, 2011. Handedness was recorded for 592 fishing and poking bouts by 14 bonobos. Following prior studies, handedness was defined from the percentage of bouts that were done with only the left hand, with 60% or more being left-handed and 40% or less being right-handed. This study group showed a left hand bias among individuals; 9 with left-handed bias (66.7% to 100% of tasks) and 6 with right-handed bias (39.4% to 0% of tasks). The group showed more left-handed (n=311) than right-handed (n=281) bouts, with 93 bouts involving both hands. Right-handed bouts were longer in duration, averaging 113 seconds, with left-handed bouts averaging 79 seconds. The frequency of left and right-handed bouts by individuals was compared to an expectation calculated from the 60% right-handed and 40% left-handed criteria from previous studies using a Replicated Goodness of Fit test and found to be significantly different (G=37.743, p<0.001) with significant heterogeneity (G=171.649, p < 0.001). We conclude that this group of bonobos is predominantly left-handed.