Chimpanzees (Pan troglodytes) start to yawn if they see a human-looking android yawn, according to a study published in the journal Scientific Reports.
The study shows chimpanzees will yawn and lie down in response to yawns made by an android, suggesting that it may act as a cue to rest rather than simply triggering an automatic response. This is the first study to show that animals can yawn in response to an object.
Contagious yawning – where seeing a yawn from another animal triggers a yawn – is observed in mammals and some fish. While the evolutionary origins of yawn contagion are still unknown, some animals, including humans, can catch yawns from other species.
To test the responses of chimpanzees, a team from City, St George’s, University of London used a human-looking android head to test the responses of 14 adult chimpanzees aged between 10 and 33 years at the Fundació Mona Primate Sanctuary in Spain.
The android head generated three facial expressions – “yawning”, “gaping”, and “neutral” – with each facial movement lasting 10 seconds.
Results showed that adult chimpanzees started to yawn when the android displayed a fully wide-open mouth (“yawning” expression) and exhibited a reduced response when the mouth was partially opened (“gaping”). They never yawned when the android’s mouth was closed (“neutral”). In addition, when they yawned, they also gathered bedding material and prepared to lie down.
“Our findings show that chimpanzees exhibit yawn contagion when triggered by a non-biological inanimate agent, a humanoid android, that looks like it is yawning. Despite its elusive primary functions – we still don’t know exactly why we yawn, let alone why yawning is contagious – yawning may still have an evolutionarily old, non-verbal communicative role, and its contagious aspect may help us find out more about how humans and animals developed ways of communication and social interaction,” said lead author Dr Ramiro Joly-Mascheroni.
“Exploring the yawning responses of primates towards an artificial agent helps us to understand the mechanism of social cognition and interactions beyond humans. This interdisciplinary research enhances the collaboration of disciplines such as psychology, robotics, and zoology,” concluded Professor Beatriz Calvo-Merino.
Joly-Mascheroni, R., Forster, B., Llorente, M. et al. Chimpanzees yawn when observing an android yawn. Sci Rep 15, 18002 (2025). https://doi.org/10.1038/s41598-025-98639-z