Just kidding: the evolutionary roots of playful teasing.

Accounts of teasing have a long history in psychological and sociological research, yet teasing itself is vastly underdeveloped as a topic of study. As a phenomenon that moves along the border between aggression and play, teasing presents an opportunity to investigate key foundations of social and mental life. Developmental studies suggest that preverbal human infants already playfully tease their parents by performing 'the unexpected,' apparently deliberately violating the recipient's expectations to create a shared humorous experience. Teasing behaviour may be phylogenetically old and perhaps an evolutionary precursor to joking. In this review, we present preliminary evidence suggesting that non-human primates also exhibit playful teasing. In particular, we argue that great apes display three types of playful teasing described in preverbal human infants: teasing with offer and withdrawal, provocative non-compliance and disrupting others' activities. We highlight the potential of this behaviour to provide a window into complex socio-cognitive processes such as attribution of others' expectations and, finally, we propose directions for future research and call for systematic studies of teasing behaviour in non-human primates.