A recent study published in *iScience* suggests that bottlenose dolphins might use open-mouthed expressions resembling a “smile” as a form of communication while playing with each other. Researchers observed 22 dolphins in Italian and French marine parks and noted that dolphins “smiled” mostly during play with each other, rarely when interacting with humans or playing alone. These “smiles” were likely used to prevent play from escalating into aggression, as dolphins “smiled” back at each other around one-third of the time.
The findings align with similar behaviors in other mammals like humans and monkeys, which use open-mouth displays during play, thought to stem from modified biting actions. Although the expression looks like a smile to humans, dolphin expert Heather Hill cautions against directly interpreting it as such, as dolphins use open-mouth displays in various other contexts, including aggression.
Dolphins are known for their playfulness. iScience Maglieri et al
The study also highlights the role of vocal signals during dolphin play, a topic researchers recommend for further study. Though all dolphins in the study were captive, Hill suggests that this “smiling” behavior likely also occurs in wild dolphins, though potentially less frequently due to their need to hunt and avoid predators. Future research with wild dolphins could confirm if these expressions function similarly in natural settings.
