Many social animals collaborate, but only humans supposedly engage in joint action – cooperative interactions that involve normative, mutually obligating joint commitments (JCs). JC presumably facilitated the evolution of hyper-cooperation observed in human societies, including complex collaborations like governments, and has likely played a pivotal role in human evolution. Given the significance, there has been a long-standing interest in the developmental (i.e. ontogenetic) and evolutionary origins of human joint action capacities like JC.
One classical approach to assess the evolutionary and developmental building blocks of JC involves experiments with human children and nonhuman great apes (mostly chimpanzees), where individuals of each group interact with a human experimenter by playing a social game. In this paradigm, the experimenter then typically stops to interact, causing a sudden interruption to the task. Former results of this research showed that humans, yet never or rarely apes, reengage passive experimenters. This has been taken as evidence that humans engage in joint actions via JC, yet that apes’ interactions rely on egoistic motives.
Although these findings are important for our understanding of how human joint action evolved, it is important to note that such tasks are anthropocentric, as they involve engagement with human confederates and human-centric tasks. Drawing on a more ecologically valid approach, newer research related to this project demonstrated that when apes interact with conspecifics naturally, they appear to exhibit specific joint action capacities like JC. Yet firm conclusions cannot be drawn unless the following empirical issues are solved: i) behaviours do not permit insights into internal states, ii) comparative joint action research is still in its infancy, lacking a holistic picture of affective and behavioural processes supporting coordination, and iii) previous ape studies are deficient of critical experimental controls.
Building on and expanding unique expertise in this domain, this projects goal was to overcome the former challenges by pioneering a comparative investigation of spontaneous joint action coordination in human children and bonobos. Developing cutting-edge automated posture tracking and thermal imaging techniques, as well as timely experimental controls, this project explored pivotal joint action features like the fixing of communicative trouble, bodily synchrony, and JC-related emotions. The outputs will provide important insights into whether humans and apes share basic joint action capacities, notably related to JC, and hence reassess the question of the evolutionary building blocks of human sociality.
