Bottlenose dolphins use the ‘open mouth’ facial expression – analogous to a smile – to communicate during social play, researchers say. — AFP
Some pet owners are convinced they’ve seen their dog or cat smile, but it’s unlikely to be the case.
Experts in the field can’t say whether animals can smile or not. However, researchers from France and Italy claim to have observed this behaviour in dolphins.
A research team led by Dr Elisabetta Palagi of the University of Pisa (Italy) studied the behaviour of just over 20 bottlenose dolphins (Tursiops truncatus) living in captivity in two animal parks, one in Italy and the other in France.
The scientists used over 80 hours of recordings of these marine mammals, featuring them making 1,288 smile-like facial expressions.
The scientists noted that, in 90% of cases, the dolphins made these smile-like expressions when socialising with their fellow dolphins.
They tended to “smile” when they were in their playmate’s field of vision. In 33% of cases, their playmates returned their “smiles,” attesting to the intentional nature of the action.
“Some might argue that dolphins mimic others’ open-mouth expressions by pure chance, given that they are often engaged in the same activity or context. But this doesn’t explain why the probability of imitating another dolphin’s open-mouth expression within one second is 13 times higher when the receiver actually sees the original expression,” Palagi told New Scientist magazine.
Evolutionary origin
It’s hard to confirm whether dolphins smile the way we humans do. But the presence of this mimicry in these aquatic animals suggests that smile-like facial expressions have a very ancient evolutionary origin.
“Although we are far from understanding the evolutionary origins of play (monophyletic vs polyphyletic) and the ability of animals to finetune their playful sessions, the pervasive presence of open-mouth signals and rapid mimicry in the mammal phylogenetic tree indicates the relevance of such visual mechanisms in shaping complex communication,” the researchers write in their paper.
Apart from dolphins, primates can also smile, and even laugh. All these discoveries are revolutionising our vision of animals’ cognitive capacities, and encouraging us to see them as sentient beings with the ability to experience feelings and sensations. – AFP Relaxnews
