Does playful teasing help great apes learn about social relationships?

Understanding social relationships is critical to succeeding in primate societies. In species with complex social networks (including humans), correctly predicting the strength of one's social relationships or bonds helps individuals better navigate future interactions. Social contingency-behaviour that depends on and directly responds to another's actions-is a key feature of interaction that provides opportunities to learn about these relationships. We propose that playful teasing in great apes represents a specialized form of social contingency that enables relationship assessment in a relatively safe context. Playful teasing involves one individual pestering, harassing or provoking another in a playful manner. An ape can learn about their bond by observing how a social partner responds to mild provocation-seeing how far they can push the other before receiving an explicitly negative response. Since responses range from mild aversion to benign tolerance to reciprocal play, the teaser can gain valuable information about relationship quality through monitoring the socially contingent responses to teasing actions. This form of learning through contingency may have evolved as a relatively low-risk method to assess social relationships through direct feedback, though several alternative explanations exist. We examine multiple evolutionary hypotheses for playful teasing and offer suggestions for future empirical testing. This article is part of the theme issue 'Mechanisms of learning from social interaction'.