A Fascinating Emotional Connection : What If Dolphins Smile At Each Other for the Same Reason We Do?

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Dolphins are the most adorable and interesting marine creatures in the sea, don't you think? Their adorable acrobats in the sea is another sight to look out for. But do you feel like they smile whenever they open their mouth? Scientists say dolphins don't just look like they are smiling when they open their mouths but they might just be grinning at each other, and this expression tends to be quite contagious.

Not everyone agrees that the relaxed, open mouth of the dolphin is a smile. But researchers in Europe have showcased evidence that suggests captive bottlenose dolphins also known as Tursiops truncatus use these expressions as friendly gestures.

To carry out the research, a team of scientists from institutions in Italy and France studied 11 dolphins at Zoomarine Rome and another 11 at Planète Sauvage in western France as they engaged in play with one another along with their human trainers, and independently.

The researchers observed 1,288 occurrences of open-mouthed smiles, with 92 percent happening during play with fellow dolphins, and these smiles were especially common when they were with a playmate who also seemed to reciprocate with a smile.

At the time of play fighting, researchers also suspect that a dolphin mimics another's open mouth, leading to playmates agreeing to a friendly interaction that could otherwise be misinterpreted as aggressive.

The researchers also suggest that these 'laugh faces' are playful expressions that have deep roots in mammal biology, not limited to land but also in the sea.

Evolutionary biologist Elisabetti Palagi from the University of Pisa in Italy says that they have uncovered the presence of a distinct facial display, the open mouth, in bottlenose dolphins, that showed that dolphins are also able to mirror others facial expression.

Not just in dolphins, the relaxed open mouth seen in animals like monkeys and humans like us, where we break into human laughter is a universal sign of playfulness, helping all of us to signal fun and avoid conflict.

While these findings do not entirely exclude the possibility that dolphins may utilize open mouths in different contexts, they do align with earlier hypotheses suggesting that laugh faces serve as friendly social cues derived from the act of biting.

Palagi further explains that the open mouth gesture likely originated from the action of biting, evolving over time by removing the actual biting motion and leaving only the intent behind it.

It has to be noted, that the research was only conducted among captive dolphins, so it's tough to predict how the species might use their open mouths in the wild.

Considering adaptability, switching from acoustic to visual communication can be an advantageous strategy during social play, a period when dolphins are less vigilant about potential threats from predators.

The research team argues that while they still have much to learn about the evolutionary origins of play and how animals refine their playful interactions, the widespread occurrence of open-mouth signals and quick mimicry within the mammal phylogenetic tree highlights the importance of these visual mechanisms in developing complex communication.

(This study was published in iScience)