Dolphins are one of those rare animals that humans can really relate to, because they’re intelligent enough that their actions often remind us of ourselves.

For better or worse.

In this case, it’s better – we imagine we see smiles on their little faces when they’re playing, and it turns out we’re right.

In fact, when dolphins smile at someone they like, that smile is also often reciproated as bid for bonding.

Scientists don’t think it’s an accident that a dolphin’s happy expression so closely resembles a human’s, either.

We have a tendency to read into animals’ facial expressions because humans love to anthropomorphize, but we’re not always correct in using our own interpretation of animals’ feelings.

According to Dr. Elisabetta Palagi, research proves we read into dolphins expressions correctly.

“We’ve uncovered the presence of a distinct facial display, the open mouth, in bottlenose dolphins, and we showed that dolphins are also able to mirror others’ facial expression.”

In addition, dolphins use this “smile” with each other to let everyone know when they’re fooling around and not trying to unalive you.

Palagai and her colleagues studied film of 22 captive bottlenose dolphins to try to discern how they communicate play to other dolphins and human trainers.

They found that 92% of the time a dolphin’s mouth was held open on purpose, it was during play. They almost always did this when they knew someone else was watching.

About 30% of the time, a dolphin smiled back at another dolphin who was smiling.

“Some may argue that dolphins are merely mimicking each other’s open mouth expressions by chance, given they’re often involved in the same activity or context, but 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.”

They plan to look into the correspondence between the dolphin’s smile and specific sounds, as well as eye-tracking, in the future.

It’s much harder to observe dolphins in the wild, so it’s tough to tell how much, if any, of their expressions are borrowed from their interaction with humans.

Co-existing with humans is a reason that so many dogs seem to smile as a way to bond.

Still, Palagi says the dolphins smiled less often when interacting with their trainers, so they don’t believe interacting with humans is much of an instigator for that particular facial expression.

The researchers do want to look into smile-like expressions on other animals.

“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. The open mouth gesture likely evolved from the biting action, breaking down the biting sequence to leave only the ‘intention to bite’ without contact.”

They’re still exploring why this similar feature might have developed in a wide range of mammals.

“It is difficult to know whether such similarities derive from shared evolutionary pathways or from evolutionary convergence.”

The bottom line is that if you think another animal is smiling, you just might be right.

But you’ll still want to think twice before you approach it expecting friendship to result.

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