A Ticklish Affair: Tickling Impacts Play Features in Bonobos

Heavy tickling has been reported only in humans and great apes. Because it requires complex socio-emotional/cognitive skills, it can be a model for investigating intersubjectivity origins. We examined how tickling influences the temporal, structural, and communicative organization of bonobo social play. We gathered video data from a bonobo group housed at La Vallée des Singes (France) over 3 months. By analysing 215 dyadic play sessions (27 dyads), we found that at the temporal level sessions containing tickling lasted longer than those without. Tickling reduced the total duration of pauses, although its effect on pause occurrence depended on object presence. A subset of 45 sessions (11 dyads) underwent detailed frame-by-frame analysis. Within this subset, tickling was associated with lower play asymmetry, reduced behavioral diversity, lower evenness, and less repetition, indicating more balanced, focused, yet non-repetitive interactions. Within the same subset, at the communicative level, tickling did not affect play-face reciprocity or rapid facial mimicry but was associated with reduced mutual gaze. Overall, tickling modified multiple features of bonobo play by sustaining engagement, shortening pauses, and promoting balanced behavioral participation. The selective reduction in mutual gaze, despite unchanged facial reciprocity and mimicry, suggests that coordination during tickling relies more strongly on tactile exchanges than sustained face-to-face visual orientation. By demonstrating how a specific tactile component of social play contributes to the maintenance, coordination, and sensory organization of playful interactions, these findings support tickling as a natural model for investigating the evolutionary foundations of intersubjective multimodal processes predating the human-Pan split.