1Department of Anthropology, Washington University, 2Congo Program, Wildlife Conservation Society, 3Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, 4Neuroscience Institute and Language Research Center, Georgia State University, 5Division of Developmental and Cognitive Neuroscience, Yerkes National Primate Research Center
March 26, 2015 8:15, Grand Ballroom E/F/G
The nearly universal right hand preference manifested by human populations is one of the most pronounced manifestations of population-level lateralization. Morphological and archeological evidence indicate that this behavioral specialization may have emerged among our hominin ancestors. Whether population-level behavioral asymmetries are evident in non-human animals remains a topic of considerable scientific debate, with the most consistent evidence of population-level trends emerging from studies of chimpanzees (Pan troglodytes). However, previous studies of population-level lateralization in wild apes have relied upon data sets pooled across populations to reach adequate sample sizes. Our aim was to test for population-level handedness within a single wild chimpanzee population, and also to determine if performance asymmetries were associated with handedness. To address these questions, we coded handedness and duration of fishing probe insertions from remote video footage of chimpanzee visitation to termite nests (totaling 119 hours) in the Goualougo Triangle, Republic of Congo. Similar to reports from other populations, chimpanzees in the Goualougo Triangle showed robust individual hand preferences for termite fishing. There were 46 right-handed, 39 left-handed and 4 ambiguously-handed individuals. Though we did not detect an overall significant population-level handedness (t(88)=0.83, n.s.) in this study, males showed a greater right hand preference than females. Further, we found that average dipping latencies were significantly faster for right- compared to left-handed chimpanzees. Possible explanations and evolutionary implications of taxa- and task- specific patterns of population-level laterality are discussed.