ETD

• Conflict resolution
• Facial mimicry
• Flexible communication
• Social complexity
• Yawn contagion

In this thesis, we investigate the social and communicative foundations of empathy-related behaviours in non-human primates by combining observational and experimental approaches across two monkey species living in complex yet distinct social systems—geladas (Theropithecus gelada) and rhesus macaques (Macaca mulatta). The research explores multiple layers of empathic processes, from motor synchronization and emotion recognition to strategic communicative and behavioural flexibility. First, we examine multimodal yawning and yawn contagion in geladas, revealing a context-sensitive behaviour whose acoustic component enhances contagion and coordination. Second, we analyse visually driven synchronization during play fighting, where rapid facial mimicry and mutual gaze serve as flexible means to manage risk, sustain shared engagement, and align partners’ arousal. Third, post-conflict interactions highlight communicative flexibility shaped by relationship quality and perceived risk, as well as sensitivity to others’ distress and spontaneous third-party affiliation even in despotic systems—suggesting that prosocial tendencies can emerge under competitive constraints. Altogether, these findings indicate that empathy-related responses likely arise from the interplay between cognitive and communicative flexibility shaped by the selective pressures of social complexity.