Filipa Alexandra de Abreu Paulos

For centuries, researchers have studied language evolution. Recently, the “Interaction Engine” hypothesis suggested that language arose from our unique social interaction abilities, including face-to-face interaction and cooperative turn-taking. Turn-taking has been suggested to be an ancient mechanism found across the primate order. Although turn-taking studies have been biased towards Neotropical primates, they predominantly focused on vocal turn-taking and single call types. This project aimed to bridge this gap by understanding the role of turn-taking across modalities and tackling similarities and differences to human conversational turn-taking. Thus, it investigates turn-taking in common marmosets, renowned for their vocal turn-taking abilities and that exhibit, similarly to humans, a cooperative breeding system. We addressed the following questions: Which role does turn-taking play in common marmosets’ interactions? Which elements characterizing human conversations can also be found in common marmosets’ turn-taking exchanges? The results showed that marmosets have a signal-signal and signal-action turn-taking system, although it might not be as flexible as humans’, and employ multimodal communication. Our findings highlight that turn-taking is not restricted to a single vocalization but also plays a role in other modalities, suggesting that this system may be an ancient mechanism and exploring the idea that turn-taking may be primarily multimodal.