Hallmarks of social action in the vocal turn-taking of wild common marmosets (Callithrix jacchus).

Conversational turn-taking, the orderly exchange of signals between individuals, is considered an important component of human communication and language. Comparative studies of vocal turn-taking have often been biased toward a limited number of model species and have usually examined only single call types, restricted features of human conversational turn-taking, or captive animals, thereby limiting broader understanding of turn-taking complexity and its evolutionary trajectory. Here we show that wild common marmosets engage in structured vocal exchanges that share several basic features with human conversational turn-taking. We analyzed 1,245 natural vocal interactions and found that individuals can produce multi-turn exchanges with matched call types. Marmosets used different vocalizations when interacting with group members compared to neighboring groups. These interactions were characterized by flexible turn organization, recurring call sequences, relatively short gaps between turns (approximately 1,300 ms), and structured participation involving specific individuals. Altogether, our findings highlight the complexity of vocal interaction in wild common marmosets, providing a broader view of coordination across the whole vocal repertoire and suggesting that elements of human conversational turn-taking may be present in this species and may be shared, at least in part, with other primates.