The Altruism of Mice

Years ago, a Disney-animated short showed Minnie Mouse administering first aid to Pluto the dog, and Figaro the cat of the film Pinocchio.

Recent research now shows that real mice may have a built-in instinct to revive their unconscious peers.

Three separate studies published in the journal Science have suggested that mice engage in rudimentary “first aid” when they encounter an unresponsive companion and will attempt to resuscitate them.

In the first study, lead author Li Zhang and his team found that mice encountering an unconscious cage mate engaged in a structured response.

“They start with sniffing, and then grooming, and then with a very intensive or physical interaction,” Li explained to New Scientist. “They really open the mouth of this animal and pull out its tongue.”

That last unusual maneuver actually helped clear the airways and sped up recovery from anesthesia: In about half of all cases, the unconscious mouse recovered faster than those left alone.

Also, the mice were far more likely to attempt these resuscitation-like behaviors on familiar companions than on strangers.

In another study, scientists from the University of California, Los Angeles, examined what was happening inside the mice’s brains during these revival attempts.

In their paper, they wrote that a specific region, the medial amygdala, became highly active when a mouse encountered an unconscious peer. This response was distinct from the brain activity observed when mice interacted with stressed but conscious companions, suggesting that the rescue behavior isn’t just general social engagement, but something more specific.

Meanwhile, a third study tested whether mice were responding to any sign of distress or if their actions were more targeted.

This time, researchers placed small objects in the mouths, genitals, and rectums of anesthetized mice. In 80 percent of cases, their cage mates removed the mouth obstruction but ignored objects placed elsewhere.

The findings further reinforce the idea that the creatures were instinctively focused on keeping their peer’s airway clear.

Further analysis showed that oxytocin, a hormone associated with social bonding, spiked in mice performing these revival attempts.

“To me, this looks very much like a behavior that’s driven by what I would call the altruistic impulse,” neuroscientist James Burkett, who was not involved in any of the paper, told NPR.

Still, not everyone is convinced of that explanation. Some believe curiosity could be playing a role.

Even so, the studies underscored how emergency-like responses might be more deeply ingrained in the mammalian brain than previously thought.

“Animals are engaging in the emotions and behaviors of others around them in a way that’s much richer than we previously realized,” Burkett said.