A while back, my cat, Emerson, bolted outside, refusing calls to return until a few hours later, when he swaggered home and gifted us a dead mouse. Before this, the only mice I’d had close proximity to were flashes of smokey grey that vanished beneath the fridge in my skanky-but-affordable Toronto apartment.
I was struck by how adorable this murdered mouse was and felt both a rage toward my cat for senseless killing and a rare kinship with Walt Disney, who clearly had an affection for the creatures.
Those round eyes, that little nose, those charming whiskers.
So I, for one, was unsurprised when a recent study revealed that mice seem to have facial expressions similar to our own.
Let’s cast aside for the moment the ways in which researchers elicited these mouse expressions—after all, my cat has blood on his own paws. But it seems clear, for instance, that a mouse expresses pain by flattening its ears and shifting the position of its lower jaw and nose from a “neutral” position. A sweet drink, particularly when the mouse is thirsty, generates an expression of pleasure even more than a drink when the mouse’s thirst has already been quenched.
The mouse expressions are subtle, and researchers relied largely on machine learning to discern the before and after.
“We do not necessarily know which features the computer [used] to distinguish them,” says lead researcher Nadine Gogolla, the co-author of the study from the Max Planck Institute of Neurobiology in Germany. That, she says, will be part of a future investigation.
“We would like to understand whether mice experience other emotion states,” she says, and also, “we would like to know whether mice use facial expressions for social communication and whether they can exert control over them.”
In the meantime, I will hope to avoid seeing mice expressions whether on the face of a live mouse terrorizing me in my kitchen or on the face of an adorable dead mouse whose last expression was, no doubt, terror of his own.