Overview

• Eight out of 14 adult chimpanzees at Spain’s Fundació Mona Primate Sanctuary yawned after observing an android head mimic a fully open-mouth yawn.
• Some chimpanzees proceeded to gather bedding materials and lie down in response to the android’s yawn, indicating a link between yawn contagion and rest behaviors.
• Responses were graded according to mouth aperture, with the strongest contagion to fully open mouths, reduced yawning to partial gapes and no response to closed-mouth expressions.
• The interdisciplinary team used an android head equipped with 33 motors to replicate yawning, gaping and neutral facial gestures during four 15-minute observation sessions per chimpanzee.
• The results demonstrate that visual cues alone can activate neural pathways tied to social synchronization and empathy, suggesting new directions for social robot design in animal research and welfare.