Chimpanzees have long fascinated scientists for their close behavioral and cognitive similarities to humans, and a groundbreaking new study from City St George’s, University of London, adds another intriguing dimension to this connection. Researchers have demonstrated that chimpanzees can “catch” yawns from an android designed to mimic human facial expressions. This innovative research, recently published in Scientific Reports, reveals not only the contagious nature of yawning in primates but also suggests that artificial agents like androids may serve as visual cues prompting rest behaviors in these animals.
In this pioneering experiment, the team employed an android head capable of replicating specific facial gestures—namely yawning, gaping, and maintaining a neutral expression—to observe chimpanzee reactions. The android’s facial movements spanned ten seconds each, providing a controlled and standardized stimulus for comparison across conditions. Remarkably, chimpanzees showed a significant increase in contagious yawning when observing the android openly yawning, but responses diminished when the mouth was only partially open and vanished entirely with closed mouths. This graded response underscores the sensitivity of these primates to nuanced social signals and hints at the sophisticated mechanisms underpinning yawn contagion.
Yawning is a ubiquitous behavior across vertebrates, especially mammals, yet its origins and functions have remained elusive despite decades of research. Observations of contagious yawning—where one individual’s yawn triggers another to yawn—have primarily been linked to biological and neurological factors associated with empathy and social bonding. However, this study circumvents biological triggers by using an inanimate, non-biological agent, suggesting that the contagion may extend beyond automatic neurological reflexes to involve more complex social cognition influenced by visual cues and context.
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The research was conducted with 14 adult chimpanzees ranging between 10 and 33 years old at the Fundació Mona Primate Sanctuary in Spain. This sanctuary setting provided an optimal environment to conduct studies with minimal stress and interference. By examining the chimpanzees’ behavioral responses to the android’s facial expressions, researchers could decode subtle social signals without the variability introduced by live models. Importantly, yawning was accompanied by additional behaviors only seen in response to the fully open mouth yawn expression, including the gathering of bedding material and assuming a lying down posture, behaviors typically associated with rest or sleep.
From a neurological perspective, contagious yawning in primates is hypothesized to involve mirror neuron systems that allow an individual to simulate or internalize others’ actions. This mirroring facilitates social synchronization and may promote group cohesion. The fact that chimpanzees responded to an android—an entity devoid of biological motion or scent—supports the idea that visual cues alone can activate these neural circuits. This finding is both surprising and revealing, indicating that abstract representations of social stimuli are sufficient to engage deep-rooted behavioral patterns.
The implications of these findings stretch beyond primatology into robotics and artificial intelligence. The study’s interdisciplinary approach blends cognitive neuroscience with robotics, opening pathways for the design of social robots that can interact meaningfully with animals, potentially benefiting conservation, research, and welfare programs. Robots designed to elicit natural behaviors in animals could revolutionize how we study and support wildlife and captive species, granting insights into social cognition and communication that remain inaccessible through traditional methods.
Lead author Dr. Ramiro Joly-Mascheroni emphasized that despite the ongoing mystery surrounding the primary function of yawning, its contagious nature and communicative aspects likely represent an evolutionarily ancient form of non-verbal interaction. This contagion may play a crucial role in social coordination and vigilance within groups, a hypothesis that gains credence from these new findings linking inanimate cues to primate responses. By revisiting yawning contagion through the lens of artificial agents, scientists can explore the evolutionary and neurocognitive pathways facilitating social communication across species.
Professor Beatriz Calvo-Merino underscored the value of integrating disciplines such as psychology, robotics, and zoology in this research. By exposing primates to artificial social agents, the study transcends traditional experimental paradigms, offering novel methodologies to probe social cognition in ways previously unattainable. This cross-disciplinary approach not only enriches the understanding of primate behavior but also propels forward the development of synthetic biology and human-robot interactions, potentially informing therapeutic and educational interventions in the future.
Interestingly, the chimpanzees’ graduated response to facial expressions—maximal yawning to wide-mouth ‘yawns’, mild reactions to gaping, and negligible response to neutral—indicates a finely tuned perceptual mechanism capable of discriminating subtle facial cues. This sensitivity suggests that yawning contagion is not a blunt automatic reaction but rather a modulated behavioral response, potentially linked with social context and individual recognition of intent or state within their social group.
The study also invites reflection on the evolution of empathy and social bonding mechanisms. Since contagious yawning has been associated with empathy in humans, the fact that chimpanzees respond to an android’s simulated yawns hints at the presence of an empathy-like process or a fundamental mechanism of behavioral synchronization that requires only visual stimulus. This finding challenges the notion that biological kinship or emotional connection is always necessary to provoke such responses, broadening the conceptual framework of social cognition.
While this study pioneers the demonstration of contagious yawning triggered by a robotic stimulus in chimpanzees, it raises further questions about the extent to which other behaviors or emotional states might be elicited by artificial agents. Do chimpanzees and perhaps other social animals respond similarly to different expressions or actions performed by robots? Can future designs mimic more complex social signals, and will animals distinguish these from genuine biological agents? These questions mark exciting frontiers for future research.
Understanding the underpinnings of social cognition through such innovative methodologies provides critical insight into the evolution of communication, not only in our closest relatives but potentially tracing back to the origins of social behavior in mammals and beyond. If yawning contagion can be elicited by non-biological agents, it suggests that sensory perception and cognitive mechanisms co-evolved to interpret and synchronize group behavior using the most salient social cues, which may have profound implications for our understanding of animal societies.
In summary, this compelling research bridges the world of artificial intelligence and primate behavioral science, unveiling the power of visual stimuli in eliciting natural social behaviors such as contagious yawning. It opens pathways to explore the neural, cognitive, and evolutionary factors behind non-verbal communication and social interaction. As robotic technology advances, such interdisciplinary studies hold great promise for unraveling the complexities of animal minds and their communicative worlds.
Subject of Research: Animals
Article Title: Chimpanzees yawn when observing an android yawn
News Publication Date: 5-Jun-2025
Web References: 10.1038/s41598-025-98639-z
Keywords: Behavioral ecology, Ecological adaptation, Ecology, Developmental neuroscience, Developmental biology, Life sciences, Sociobiology, Evolutionary biology
Tags: androids mimicking human expressionsartificial agents and animal interactionchimpanzee behavior and cognitionCity St George’s University researchcognitive similarities between humans and chimpanzeescontagious yawning in primatesevolutionary significance of yawninginterdisciplinary animal behavior studiesprimate response to visual cuesscientific reports on primate behaviorsocial signals in animalsstudy on yawning and rest behaviors