What can behavioural structure tell us about motivation? Insights from object play and foraging in Balinese Long-Tailed Macaques

Current research is not unanimous on whether object play is motivationally linked to foraging, due to a lack of systematic comparison of the behavioural structure of both activities. This thesis aimed to address this gap by comparing the ethograms and kinematics of two object-directed activities, a seemingly playful one (stone handling), and a functional one (food processing) in Balinese long-tailed macaques. My results indicated that percussive stone handling in this species was more frequent, prevalent, and complex than in other macaque species. I also found that stone pounding was a playful activity motivationally distinct from foraging (nut pounding), and that some of the defining structural characteristics of play (e.g., exaggeration, variability, incompleteness) were not simply a consequence of immaturity, but indeed inherent components of playful actions, regardless of the age of the performer. This work contributes to understanding the mechanisms and evolution of questionably adaptive behaviours, like play