Dolphins’ open-mouth behaviors during play are like smiles, a study claims

Dolphins are known for what appear to be big, contagious smiles. But do they correctly, well, smile?

The reply, in keeping with a fresh in trying out about of dolphin play, is a convincing “possibly.” Dolphins use their smile-like facial expression when interacting with their mates one day of playful times, researchers report October 2 in iScience. That, the team says, suggests the cetaceans are doing something equivalent to a human laugh. But other experts urge caution in attributing humanlike behavior to creatures whose intent we're ready to just guess at.

Scientists have long known anecdotally that dolphins can display a behavior often called “open mouth,” which people often associate with a smile. Other animals, like primates, could make the same relaxed open mouth to speak one day of playful contexts (SN: 6/10/15). “It’s a signal that communicates, ‘Look, I’m just playing!’,” says Elisabetta Palagi, a comparative ethologist on the University of Pisa in Italy. “Like after we put a smiley face on a cell message that can well well be misleading.”

Alternatively, such behavior has never been studied in-depth in dolphins. So Palagi and colleagues recorded nearly 900 play sessions among 22 captive bottlenosed dolphins (Tursiops truncatus), filming nearly 1,300 “smiles” from 17 animals. The researchers filmed dolphins playing on my own, with other dolphins and with humans.

The dolphins mainly showed their open-mouth behavior while fidgeting with a companion, generally any other dolphin, the team found. When the animals were playing on my own, they practically never did. Furthermore, about ninety %of open-mouth expressions were performed when the dolphins were in their playmate’s field of view.

Also, when the sort of “smiles” become seen by any other dolphin, in about a 0.33 of cases, the receiver also “smiled” back in lower than a second. That, Palagi says, is an analogous time that elapses between a human perceiving a facial expression and then mirroring it.

The outcomes suggest that the dolphin’s open-mouth expression is “an exceptionally sophisticated form of conversation,” Palagi says, that can well well be used on the side of acoustic signals (SN: 12/7/17). While it’s tough to assert whether it had the same evolutionary origin as humans’ smile, it most probably has “the same function,” since the context and the way within which it occurs is an analogous as in humans, she says.

“Being ready to see some evidence that’s demonstrating [dolphin’s open-mouth behavior] in a play context is in point of fact great,” says animal behavioralist Erin Frick, who become not involved with the in trying out about. But, she adds, dolphins use mouth opening in other contexts as well as, equivalent to displaying a threat in an aggressive context. “I don’t think open mouths are always communicating play. I suspect they do have a role in play,” says Frick, of Eckerd College in St. Petersburg, Fla.

But Palagi is convinced the open mouth is dedicated only to playful contexts: When the dolphins in her in trying out about were acting aggressively, her team didn’t see the animals performing this particular open-mouth behavior. “At some stage within the few aggressions we witnessed, we saw the opening of the mouth, but after this extremely rapid opening, either a bite or an attempted bite followed.”

Regardless, Frick just seriously is not going to be to any extent further ready to call the behavior a smile. “It’s not the same,” she says. “Nevertheless it still has an exceptionally … functional form in how they impart.”

Like Frick, comparative psychologist Heather Hill also urges caution in interpreting the plain smiles. “I'm not super relaxed calling it a ‘smile,’ on condition that delphinids and whales use the open mouth display in quite some social contexts,” says Hill, of St. Mary’s University in San Antonio.

Palagi is cognizant of the hesitancy. “There's a sturdy debate if in nonhuman animals, the act of smiling or laughing … is driven by emotional arousal or intention,” she says. “We were extremely conservative and simply referred to facial display”.

Palagi adds, “It truly is miles difficult to assert if [the open mouth] in dolphins conveys an emotional mood or is used to simply keep up a correspondence to others, ‘Hey, don’t be scared, I am just playing!’, or both.” One thing the team desires to research is whether or not the presence of open-mouth behavior alters play sessions in any way. Maybe “laughing together” — if it truly is indeed what it is a ways — makes the dolphins play together longer.