Yawning is highly contagious, yet both its proximate mechanism(s) and its ultimate causation remain poorly understood. Scholars have suggested a link between contagious yawning (CY) and sociality due to its appearance in mostly social species. Nevertheless, as findings are inconsistent, CY’s function and evolution remains heavily debated. One way to understand the evolution of CY is by studying it in hominids. Although CY has been found in chimpanzees and bonobos, but is absent in gorillas, data on orangutans are missing despite them being the least social hominid. Orangutans are thus interesting for understanding CY’s phylogeny. Here, we experimentally tested whether orangutans yawn contagiously in response to videos of conspecifics yawning. Furthermore, we investigated whether CY was affected by familiarity with the yawning individual (i.e. a familiar or unfamiliar conspecific and a 3D orangutan avatar). In 700 trials across 8 individuals, we found that orangutans are more likely to yawn in response to yawn videos compared to control videos of conspecifics, but not to yawn videos of the avatar. Interestingly, CY occurred regardless of whether a conspecific was familiar or unfamiliar. We conclude that CY was likely already present in the last common ancestor of humans and great apes, though more converging evidence is needed.

Many social species, humans included, mimic emotional expressions, with important consequences for social bonding. Although humans increasingly interact via video calls, little is known about the effect of these online interactions on the mimicry of scratching and yawning, and their linkage with trust. The current study investigated whether mimicry and trust are affected by these new communication media. Using participant-confederate dyads ( n = 27), we tested the mimicry of four behaviours across three different conditions: watching a pre-recorded video, online video call, and face-to-face. We measured mimicry of target behaviours frequently observed in emotional situations, yawn and scratch and control behaviours, lip-bite and face-touch. In addition, trust in the confederate was assessed via a trust game. Our study revealed that (i) mimicry and trust did not differ between face-to-face and video calls, but were significantly lower in the pre-recorded condition; and (ii) target behaviours were significantly more mimicked than the control behaviours. This negative relationship can possibly be explained by the negative connotation usually associated with the behaviours included in this study. Overall, this study showed that video calls might provide enough interaction cues for mimicry to occur in our student population and during interactions between strangers. This article is part of a discussion meeting issue ‘Face2face: advancing the science of social interaction’.

Many social species, humans included, mimic emotional expressions, which has important consequences for the social bond. Although humans are more and more interacting via video calls, little is known about the effect of these online contexts on mimicry of phylogenetically old behaviors, and their linkage with trust. The current study aims to investigate whether mimicry and trust are affected by new communication media. Using participant-confederate dyads, we tested the mimicry of four behaviors (target, frequently observed in emotional situations - yawn and scratch; control – lip-bite, face-touch), across three different conditions: watching a pre-recorded video, online video call, and face-to-face. Trust in the confederate was assessed via a trust game. Our study reveals that (i) mimicry and trust do not differ between face-to-face and video calls, but they are significantly lower in the pre-recorded condition; (ii) target behaviors are significantly more mimicked than the controls; (iii) as mimicry increases, trust in the confederate decreases. This negative relationship can possibly be explained by the negative connotation usually associated with the behaviors included in this study. Overall, the study shows that humans got used to video calls as they provide enough interaction cues for mimicry to occur.

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