The smile of a dolphin could indicate their playful nature

Dolphins seem to make open-mouthed expressions most often when being watched by playmates, suggesting that such expressions may be similar to human smiles.

Although we often recognize these as smiles, there is little research into dolphin facial communication.

Want to know more? Elisabetta Palagi Researchers from the University of Pisa in Italy analyzed the behavior of 22 captive bottlenose dolphins (Tursiops truncatus). It takes place in two wildlife parks: Zoomarine Rome in Italy and Planete Sauvage in Port-Saint-Père, France.

Over 80 hours of footage, the team observed a total of 1,288 open-mouthed facial expressions during social play sessions. More than 90 percent of these events occurred during play between dolphins, and the rest occurred during dolphin-human interactions.

Animals were more likely to adopt an open-mouthed expression when their face was within the playmate’s field of view, 89% of the time it was displayed in this situation. When their playmate saw the smile, they smiled back 33% of the time.

“One might argue that dolphins imitate other people’s open-mouthed facial expressions purely by chance, as they are often engaged in the same activity or situation,” Paragi says. “But this does not explain why recipients are 13 times more likely to imitate another dolphin’s open-mouthed expression within one second when they actually see the original expression.”

Other animals, such as monkeys, wolves, and meerkats, may relax and open their mouths to make a “playful face,” but whether this is driven by emotion or a way to communicate intent remains unclear. There is a discussion.

“Is the dolphin’s open-mouthed expression conveying an emotional mood, or is it simply used to tell others, ‘Don’t be scared, we’re just playing!’, or both?” It’s not easy to determine whether that’s the case,” Palagi said. .

She says the study can’t say conclusively whether it’s comparable to a human smile. “We do not claim that a single study will reveal the communication strategies of dolphins during play. However, we would like to open up new areas of research that also take into account visual elements.”

Luciana Moller Researchers from Flinders University in Adelaide, Australia, say that dolphin open-mouth behavior occurs in a variety of situations, including aggressive, sexual, and social interactions. This means that it can’t necessarily be interpreted as a smile, as this is a very versatile signal.

She notes that making sounds could have been a factor in the dolphins opening their mouths, but the study did not examine acoustic recordings.

Another drawback is that they studied small groups of dolphins in captivity, so their behavior may not reflect their behavior in the wild.

“Free-living dolphins have much more space to interact and chase each other while playing, and are often found in waters with poor visibility,” Moller says. . “Visual signals may to be as effective as acoustic signals in these situations.”