Captive chimpanzees' manual laterality in tool use context: Influence of communication and of sociodemographic factors.
Understanding variations of apes' laterality between activities is a central issue when investigating the evolutionary origins of human hemispheric specialization of manual functions and language. We assessed laterality of 39 chimpanzees in a non-communication action similar to termite fishing that we compared with data on five frequent conspecific-directed gestures involving a tool previously exploited in the same subjects. We evaluated, first, population-level manual laterality for tool-use in non-communication actions; second, the influence of sociodemographic factors (age, sex, group, and hierarchy) on manual laterality in both non-communication actions and gestures. No significant right-hand bias at the population level was found for non-communication tool use, contrary to our previous findings for gestures involving a tool. A multifactorial analysis revealed that hierarchy and age particularly modulated manual laterality. Dominants and immatures were more right-handed when using a tool in gestures than in non-communication actions. On the contrary, subordinates, adolescents, young and mature adults as well as males were more right-handed when using a tool in non-communication actions than in gestures. Our findings support the hypothesis that some primate species may have a specific left-hemisphere processing gestures distinct from the cerebral system processing non-communication manual actions and to partly support the tool use hypothesis.
['Prieur|Jacques|J|', 'Pika|Simone|S|', 'Blois-Heulin|Catherine|C|', 'Barbu|Stéphanie|S|']
D000819:Animal Communication D000818:Animals D005260:Female D007839:Functional Laterality D005868:Gestures D008297:Male D002679:Pan troglodytes D053001:Tool Use Behavior
Gestures Hemispheric lateralization Intraspecific communication Object manipulations Pan troglodytes