When grooming stalls: Assessing communicative repair, negotiation, and progressivity in chimpanzees.

Human social interaction is built on progressivity (the forward flow of interaction), which communicative breakdowns may disrupt. Communicative repair (resolving communicative troubles) and negotiation (a collaborative sequence to resolve communicative breakdowns) may both serve as processes to restore progressivity following breakdowns. Here, we investigated gestural redoings(reproduction of a previous signal in any form), negotiation, and progressivity in grooming interactions (N = 311) among male East African chimpanzees (Pan troglodytes schweinfurthii) in the wild. These chimpanzees produced gestural redoings as repetitions, substitutions, and modifications (N = 158) occurring at delayed temporal gaps relative to grooming turn-taking latencies. Both substitutions and negotiations (N = 219) were associated with restored progressivity. Strongly bonded pairs showed a higher likelihood of compromise outcomes during negotiation. These findings indicate that these chimpanzees employed repair-like processes associated with restored progressivity, bearing certain resemblances to those observed in human conversation-raising the possibility that such capacities may have evolutionary roots predating the emergence of language.