Lateralization and performance asymmetries in the termite fishing of wild chimpanzees in the goualougo triangle, republic of Congo

Abstract

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 hr) 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. Am. J. Primatol. 78:1190-1200, 2016. © 2016 Wiley Periodicals, Inc.

Motor skill for tool-use is associated with asymmetries in Broca’s area and the motor hand area of the precentral gyrus in chimpanzees ( Pan troglodytes )

“…First, we found no evidence of population-level handedness for this behavior, which differs from findings on hand use for termite-fishing in wild chimpanzees, which is the task our measure was designed to simulate [72,83–86]. The results also differ from findings of population-level handedness for other types of tasks in captive chimpanzees [87].…”

“…One way to address this issue would be for researchers to focus on assessing, not just hand preferences, but performance asymmetries for any given task as a means of validating their sensitivity to potential underlying functional asymmetries. Measures of performance asymmetries in hand use is fairly uncommon in research on laterality involving nonhuman primates [67–72] and this could 0be a fruitful area for further investigation.…”

“…However, there is a growing body of evidence for population-level handedness in tool use in captive and wild great apes and these results raise some questions regarding the time line for the evolution of population-level handedness. For instance, there is evidence of population-level left-handedness for termite fishing in chimpanzees [72,85,89,90], while right-handedness has been reported for wadge dipping, ant dipping, for some motor actions involved in pestle pounding [83,84,91–93] and other forms of tool use [94,95]. One challenge in these results, much like many studies of handedness in nonhuman primates, is the fact that asymmetries vary depending on the type of tool-use task.…”

Laterality of Grooming and Tool Use in a Group of Captive Bonobos (Pan paniscus)

“…Lonsdorf and Hopkins [2005] suggested that left hand preference was more prevalent than right hand preference (task specialization) among the Kasekela community. Central chimpanzees (P. troglodytes troglodytes) in the Goualougo Triangle exhibited strong individual hand preference when termite fishing; however, there was no significant overall population-level bias [Sanz et al, 2016]. Collectively, these data suggest that termite fishing elicits strong hand preference.…”

“…Among captive bonobos, we predicted that bimanual asymmetrical grooming would elicit hand preference given its increased complexity, whereas unimanual grooming would not [Fagot and Vauclair, 1991;Hopkins, 1995;Leca et al, 2011]. Based on tool use data from captive bonobos [Chapelain et al, 2011;Hopkins et al, 2011;Bardo et al, 2015;Hopkins et al, 2015] and wild chimpanzees Marchant 1992, 1996;Lonsdorf and Hopkins, 2005;Bogart et al, 2012;Sanz et al, 2016], we anticipated significant individual hand preference for tool use. While Bardo et al [2015] found task specialization in a food extraction task among captive bonobos, this group bias has only been demonstrated in some studies of wild chimpanzees.…”