Audible Yawns in a Non-Human Species May Convey Important Social Information
taylorvich writes:
https://phys.org/news/2024-01-audible-human-species-convey-important.html
Most of us are familiar with yawn contagion, which is the act of spontaneous yawning when someone nearby yawns, often but not always audibly. For humans, yawning can emanate from fatigue or boredom, and either seeing or hearing someone else yawn may start a chain reaction.
Many animal species also yawn when they're tired, and yawn contagion is known to occur among various social animals including certain apes, monkeys, lemurs, pigs, wolves, domestic dogs, lions, spotted hyenas, and more. But other than humans, only one species-the gelada (Theropithecus gelada), a species of Old World monkey-is known to yawn audibly.
Earlier studies have explored yawn contagion within and between various species; for example, some work has shown that dogs will yawn in response to the sound of human yawns. But to date, there have been no known studies on intraspecific audibly-triggered yawn contagion in a non-human species.
Now a research team from France and Italy has specifically studied how the sound of gelada yawns affects their conspecifics. The team's work is published in Scientific Reports.
Geladas, also known as bleeding-heart monkeys, are endemic to Ethiopia. They live in multi-level societies that include units, teams, bands, and communities. Core units either include a single reproductive adult male with multiple adult females, their young, and at least one follower male; or only young adult and adolescent males no longer living within their birth units.
Similar to humans, geladas enjoy rich and complex vocal communication. According to the new study, "A similar evolutionary social landscape, with similar challenges (e.g., need of group coordination with subjects not always in visual contact), has indeed possibly led to the emergence of multimodal communication in both species."
Existing findings show that yawning geladas, mostly males, emit a loud vocal sound that does not arise solely from inhaling and exhaling. While the researchers behind this study knew that visually-based yawn contagion could affect geladas, they wanted to find out whether the sound of yawning without a visual cue would result in a similar effect.
Journal Reference:
Pedruzzi, L., Francesconi, M., Palagi, E. et al. The sound of yawns makes geladas yawn. Sci Rep 14, 361 (2024). https://doi.org/10.1038/s41598-023-49797-5
Read more of this story at SoylentNews.