In a fascinating discovery, scientists have found that bottlenose dolphins exhibit what appears to be a “smiling” expression when engaging in playful activities. This expression, often interpreted as a smile by humans, may serve as a communication tool between dolphins to ensure their playful interactions remain light-hearted and do not escalate into aggression. The new research, published in the journal iScience, sheds light on the intricate social behaviour of dolphins and provides fresh insights into how these marine mammals communicate during play.
The Study Behind the Dolphins’ ‘Smiles’
The study was carried out by a team of researchers from institutions in Italy and France, who observed a total of 22 dolphins: 11 at the Zoomarine Rome and 11 at Planète Sauvage in western France. These dolphins were monitored during different scenarios, including play sessions with each other, interactions with human trainers, and solitary activities. The researchers’ findings were compelling—most of the “smiles” were recorded during play between dolphins, rather than with their human trainers or during solo activities.
The researchers noted that the dolphins’ “smile” involved an open-mouthed expression, which frequently occurred when one dolphin was within another’s line of sight. Interestingly, the dolphin on the receiving end of the “smile” returned the gesture about a third of the time. This led the scientists to theorize that the open-mouthed expression serves as a form of communication, potentially helping the dolphins avoid misunderstandings that could lead to aggression.
A Means to Keep the Peace?
One of the key hypotheses emerging from the study is that the dolphins’ smile-like expression may help maintain the playful nature of their interactions, ensuring that the games don’t devolve into conflict. By “smiling” at each other, dolphins may signal to their playmates that their actions are intended to be playful, not aggressive. This behaviour appears to be particularly relevant during social play, a key part of dolphins’ lives, which includes activities such as leaping, breaching, and surfing through waves.
However, the study also cautions against reading too much into the dolphins’ “smile.” Heather Hill, a dolphin-communication expert and professor of psychology at St. Mary’s University in Texas, who was not involved in the research, offered a more measured interpretation of the findings. “While it seems reasonable to conclude that this is a form of communication, I’m hesitant to label it a smile in the way humans or other primates would,” she said. Hill explained that dolphins use the same open-mouth display in other contexts, including solitary or aggressive behaviours, which complicates the idea that it is a simple expression of joy or camaraderie.
Playful Creatures With Complex Communication
Dolphins have long been celebrated for their playfulness and complex social structures. Much loved by humans, these marine mammals engage in a variety of playful behaviours, from chasing each other to performing acrobatic stunts in the water. Until now, however, there has been little research into how dolphins use facial expressions during play, despite studies in other mammals, such as humans and monkeys, suggesting that open-mouthed, smile-like expressions during play are common across species.
The latest findings offer a glimpse into how dolphins use visual cues during play to maintain harmony within their social groups. The study revealed that in 92% of cases, dolphins displayed their “smiles” when playing with each other, rather than with humans or alone. This discovery highlights the importance of social interaction in dolphin play and offers a potential explanation for how they communicate to avoid misunderstandings.
More Than Just a Smile?
Despite the promising findings, researchers remain cautious about drawing direct parallels between human smiles and the dolphins’ expressions. As dolphins also use the open-mouth display in aggressive or solitary contexts, it is clear that more research is needed to understand the full range of meanings behind this behaviour.
The study did not record vocalisations during play, another important aspect of dolphin communication. Researchers believe that dolphins use a combination of whistles and visual cues to coordinate their actions and ensure that their playful encounters stay on track. “Dolphins have developed one of the most intricate vocal systems in the animal world, but sound can also expose them to predators,” explained Livio Favaro, a zoologist at the University of Turin and the lead author of the study. He noted that vocalisations and body language work together during social play, allowing dolphins to cooperate while staying alert to potential dangers.
Future Research: Captivity vs. The Wild
All the dolphins observed in this study were in captivity, raising the question of how these behaviours might differ in wild populations. Heather Hill pointed out that while the “smiling” behaviour likely occurs in the wild, it may be less frequent, as wild dolphins spend more time hunting for food and avoiding predators. Future research could explore whether wild dolphins use similar facial expressions during play and how often this behaviour occurs in natural settings.
As researchers continue to unravel the complexities of dolphin communication, the findings of this study serve as an exciting step forward in understanding the rich social lives of these intelligent marine mammals. Whether or not we can truly call it a “smile,” one thing is clear—dolphins are using sophisticated visual signals to navigate their playful interactions.
This new research not only deepens our understanding of dolphin behaviour but also reminds us of the remarkable ways in which animals communicate, often in ways that mirror our own social interactions. The study opens the door for future exploration into how dolphins use both vocal and visual cues to maintain harmony in their complex social environments.
