Mice reveal moods through facial expressions

Don’t pull a face! A mouse’s face changes depending on its feelings. © Kuhl

German researchers have discovered that mice move their ears, cheeks, and eyes in response to different sensory experiences, indicating that the creatures might experience emotions.

What’s happening

Sucking on a lemon produces an almost universal reaction. Eyes squint, mouth puckers, face wrinkles up. It is an automatic response, and we know what that facial expression means: disgust. Now, scientists have found that mice react in similar ways, indicating joy, pain, nausea, disgust, and fear.

Find out more

Nearly 150 years ago, Charles Darwin proposed that facial expressions in animals might provide a window on to their emotions. Now, we have technology advanced enough to put his theory to the test.

In a three-year study, neuroscientists in Germany used artificial intelligence to recognise muscle movements in mice, barely visible to the human eye. They provided them with stimuli, like sweet foods, to trigger different reactions.

Each time, the mice’s expressions changed in intensity according to how strong the triggers had been. Using brain scans, the team found neurons that fired when making particular facial expressions. The findings could give scientists insight into how human brains process emotional feelings.

Do mice have emotions?

Some say…

They must do! This is clear evidence that mice react to varying situations with facial expressions. As the movements are stronger and last longer when the stimulus is stronger, this suggests they have an emotional range. The discovery could allow us to understand far more about the human brain, and maybe find more similarities between species.

Others think…

If we think of emotions in the human sense, probably not. Humans experience nearly 30 different emotions, some of which are physical, and many social. While the mice move their faces based on brief physical experiences, it is unclear if the expressions truly reflect emotions. More research is needed to find out if mice react to social triggers.

You Decide

  1. Are emotions a human quality?

Activities

  1. Make a list of as many emotions as you can think of, and then try to make faces to express them. Test your household to see if they can guess each one, and note the most difficult ones!

Some People Say...

“There is no fundamental difference between man and animals in their ability to feel pleasure and pain, happiness, and misery.”

Charles Darwin

What do you think?

Word Watch

Nausea
A feeling of sickness.
Charles Darwin
Most famous for his theory of evolution, Charles Darwin published his theory in The Expression of the Emotions in Man and Animals.
Artificial intelligence
AI for short, this is intelligence demonstrated by machines.
Stimuli
Plural of ‘stimulus’: something that provokes a specific reaction.
Neurons
A specialised cell that sends impulses around the body.
Emotional range
The full range of human emotions that are felt when certain events or feelings are triggered.
Social triggers
Certain situations that make us react in a certain way, sometimes caused by past experiences. They are different for different people.

Subjects

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