Research paperReciprocal greeting in chimpanzees (Pan troglodytes) at the Ngogo community

- Reciprocal communication in chimpanzees can give insights into the evolutionary origins of structured discourse.
- Probability of reciprocity during greeting in chimpanzees is influenced by the greeting modality.
- Reciprocal greetings in chimpanzees are more likely when interactants have strong social bonds.
- Sophisticated communication may have evolved in distinct dyads showing high degrees of cooperation.

Human conversations are organized according to operative sequential features with different components of utterances being related to each other forming so-called adjacency pairings. An adjacency pair is a sequential structure produced by both speakers, consisting of two parts, with the second part being contingent upon and normatively obliged to the first part, such as greeting-greeting exchanges. The present paper investigates such ordered serial utterances in chimpanzee greeting interactions. Results show that reciprocal and structured communicative 'discourse' is relatable to the communicative modality that is chosen for greetings as well as to the social bonding between the greeting interactants. The findings of the present study are discussed in relation to the social complexity hypothesis and the current debate on the importance of the turn-taking system for language evolution.