Mice appear to empathize with pain in other critters they're familiar with, a capacity previously thought to exist only in higher primates.
When mice saw others they knew showing pain, they responded with signs of empathy, such as staying close by, according to a new study.
The mice seem hardwired to form a lower type of empathy called "emotional contagion," said Jeffrey Mogil, a McGill University geneticist, who led the study appearing in Friday's issue of the journal Science.
The contagious effect isn't triggered by conscious kindness. It's more like the way someone's yawn prompts someone nearby to do the same.
The mice were given mild noxious stimuli that caused a stomach ache-like pain.
Aside from the pain response itself, the researchers also studied how the mice interacted when they could see a cagemate in pain. The behaviour included whether they spent more time together or followed each other.
The mice didn't display the same empathetic behaviour when blocked from seeing others or when housed with strangers, the team found.
The findings reveal more about animals, and may help researchers to better understand how social interactions affect chronic pain behaviour in humans.
Mogil's team at McGill's Pain Genetics lab set out to look for genes linked to pain variability. An animal model of empathy could allow researchers to look for genes, neurochemicals and brain pathways behind empathy, the team said.