Great apes exchange signals and gaze before entering and exiting joint actions, actions that resemble those of humans; it seems that joint commitment as process was already present in our last common ancestor with Pan

Assessing joint commitment as a process in great apes. Raphaela Heesen et al. , August 11, 2021. https://doi.org/10.1016/j.isci.2021.102872

Highlights

• Great apes exchange signals and gaze before entering and exiting joint actions

• Joint action structure of both ape species resembles that of humans

• Coordinated joint action phases indicate an underlying joint commitment

• Social bonds affect joint action structure more in bonobos than in chimpanzees

Summary: Many social animals interact jointly, but only humans experience a specific sense of obligation toward their co-participants, a joint commitment. However, joint commitment is not only a mental state but also a process that reveals itself in the coordination efforts deployed during entry and exit phases of joint action. Here, we investigated the presence and duration of such phases in N = 1,242 natural play and grooming interactions of captive chimpanzees and bonobos. The apes frequently exchanged mutual gaze and communicative signals prior to and after engaging in joint activities with conspecifics, demonstrating entry and exit phases comparable to those of human joint activities. Although rank effects were less clear, phases in bonobos were more moderated by friendship compared to phases in chimpanzees, suggesting bonobos were more likely to reflect patterns analogous to human “face management”. This suggests that joint commitment as process was already present in our last common ancestor with Pan.