Maybe it’s a byproduct of my vegetarian upbringing, but I am constantly anthropomorphizing animals. I frequently talk to my dog (don’t worry, he doesn’t talk back), and when I see cows grazing I think they look happy. Sometimes people tell me I am endowing animals with uniquely human qualities, but I think they’re capable of a lot more than we give them credit for. One of these qualities that tends to be applied to humans alone is empathy, but a recent study shows that even rodents may be capable of demonstrating empathy to free a companion trapped in a cage.
The researchers took rats that had been housed together for several weeks and let one roam free in an arena, and put another in a latched cage at the center. This setup was repeated every day for 12 days, and within a few days the free rats learned to consistently open the cage door and liberate their confined cagemate. Here's a video narrated by the researcher.
In some experiments they added a second cage containing chocolate chips, and most of the time the free rat opened both cages, indicating that the value of freeing a distressed cagemate was on par with that of a delicious snack. About half the time the free rat even shared the chocolate chips with the trapped rat after setting him free.
The rats didn’t seem to be opening the cage for curiosity’s sake, since they left empty cages or cages containing a toy rat alone. The behavior also wasn’t purely motivated by the anticipation of social interaction, since they also freed the cagemate when the only exit from the cage led the caged rat to a separate arena, preventing any social contact.
One difficulty in studying a concept like empathy is that motivation is harder to measure than behavior. Even with humans, actions don’t always tell you about motivations – do you give to charity because you want to help others, or because helping others makes you feel better? This study supports the idea that even rodent behavior can be driven by empathic concern for the welfare of another. Here's a link to more details on the study.