Dolphins 'smile' at each other when they are feeling playful

Let’s dive into a world that speaks a language of its own, one of “smiles” and mirrored facial expressions, captured in the playful banter of bottlenose dolphins.

A recent study reveals that these playful creatures utilize an “open-mouth” expression, akin to a human smile, as their way of signaling fun during social play.

Unveiling of the dolphin smile

There’s a new conversation happening about the exclusive “open mouth” display of bottlenose dolphins.

As part of their playful antics, dolphins expertly utilize this display when they are within the field of view of their frisky counterparts.

What’s more, when a dolphin perceives a fellow dolphin’s open-mouth smile, it reciprocates with its own smile at least 33% of the time.

Evolution of the dolphin smile

The research was led by Dr. Elisabetta Palagi, an evolutionary biologist at the University of Pisa.

Through her extensive research, Dr. Palagi found that dolphins tend to mirror each other’s expressions. The frequency of this mimicking behavior is not random but rather a specific response to the visual cue of an open-mouth display.

“Open-mouth signals and rapid mimicry appear repeatedly across the mammal family tree, which suggests that visual communication has played a crucial role in shaping complex social interactions, not only in dolphins but in many species over time,” said Dr. Palagi.

Evolution of playful expressions

Taking a deep dive into the past, Dr. Palagi highlighted that the open-mouth gesture likely evolved from the action of biting.

The action was gradually diluted to leave only the intention to bite, without any actual contact. This open-mouth gesture, she explained, is a universal symbol of playfulness seen across social carnivores, monkeys, and even in human laughter.

It behaves as an effective signal to defuse possible confrontation, by clearly indicating intentions of fun rather than conflict. Thus, the dolphins’ playfulness, which includes acrobatics, surfing, and playfighting, is not misconstrued as aggression.

Dolphins smiling for each other

The research also revealed that dolphins frequently use the open mouth expression when playing with other dolphins, but don’t appear to use this form of communication when playing with humans or even by themselves.

In essence, the smile is a social cue primarily used in inter-species interactions. This was confirmed through meticulous observation of captive bottlenose dolphins.

Only one open mouth event was recorded during solitary play, while a substantial 1,288 open mouth events were recorded during social play sessions. As many as 92% of these events occurred during dolphin-dolphin play sessions.

Environment’s role in dolphin communication

In further exploration of dolphin behavior and their expressive smiles, it becomes evident that the environment plays a pivotal role in the manifestation of these social cues.

The aquatic realm, with its propensity for sound to travel farther and clearer underwater, complements the visual signals dolphins employ.

Spatial awareness and group dynamics are heavily influenced by the environments dolphins inhabit, such as open ocean or coastal areas, impacting their communication strategies.

Implications for human-dolphin interactions

Understanding the specifics of dolphin communication can profoundly impact how humans engage with these intelligent marine mammals.

With rising interest in dolphin-assisted therapy and ecotourism, comprehending dolphins’ social cues becomes paramount to fostering ethical interactions.

Humans must be cognizant of interpreting dolphin behaviors correctly to avoid misunderstanding playful gestures as signs of distress or vice versa.

By respecting these natural communication channels and recognizing the boundaries of interspecies interactions, humans can ensure both the welfare of dolphins and the enrichment of their own experience.

Mimicry or chance?

Can it be that dolphins are simply mimicking each other’s open mouth expressions like smiling by mere chance?

“This doesn’t explain why the probability of mimicking another dolphin’s open mouth within 1 second is 13 times higher when the receiver actually sees the original expression,” said Dr. Palagi.

Research indicates that this rate of mimicry in dolphins aligns with behavior seen in certain carnivores like meerkats and sun bears, further solidifying the premise of intentional communication.

Future research directions

While our understanding of dolphin communication has been broadened, it’s clear there’s still a lot we don’t know.

Future research is needed to explore the realm of eye-tracking to understand how dolphins see their world. Studies may also investigate the possible role of vocalizations and tactile signals during playful interactions.

“Dolphins have developed one of the most intricate vocal systems in the animal world, but sound can also expose them to predators or eavesdroppers,” noted study co-author and zoologist Livio Favaro.

“When dolphins play together, a mix of whistling and visual cues helps them cooperate and achieve goals, a strategy particularly useful during social play when they’re less on guard for predators.”

The study is published in the journal iScience

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