Rats and mice in pain make facial expressions similar to those in humans—so similar, in fact, that a few years ago researchers developed rodent “grimace scales,” which help them assess an animal’s level of pain simply by looking at its face…researchers report that other rats do pay attention to the emotional expressions of their fellows, leaving an area when they see a rat that’s suffering.
“It’s a finding we thought might be true, and are glad that someone figured out how to do an experiment that shows it,”…a rodent in pain expresses its anguish through narrowed eyes, flattened ears, and a swollen nose and cheeks. Because people can read these visual cues and gauge the intensity of the animal’s pain, Mogil has long thought that other rats could do so as well…
But the rats that saw the airbrushed images—even those with blurred bodies and upset faces—didn’t react this way. Apparently, the suffering rat’s body also communicates important information, and observing rats need to see both the face and the body in order to get the full message. Studies of nonverbal communication in humans show that we do the same thing, de Waal notes.
Neither Mogil nor de Waal are surprised that rats are able to read the emotional cues expressed in a fellow rat’s face and body. “I would be more surprised if they didn’t have this ability,” Mogil says. “If it was only something we could do, we’d have trouble explaining where the ability came from.” Finding it in rats, though, erases the need for some awkward explanation of our ability and “makes evolutionary sense.”