Study Gets to Root of Empathy in Rats

A paper published today in PloS Biology shows that one of the ways that rats avoid danger, which they are known to be quite adept at doing, is by being exquisitely sensitive to the emotions of the rats around them. These findings help explain the origins of empathy and could help advance the development of treatments for empathy disorders in humans, such as psychopathy and fronto-temporal dementia.

In contrast to the idea of empathy being a one-way street, where one person shares in the pain of another, the team from Netherlands Institute for Neuroscience discovered a more interactive process, in which animals align their emotions by mutual influences. They put two rats face to face, and then startled one of them (the demonstrator) with a brief electrical stimulation of the paws. They then observed the reaction of both rats.

"The first thing you see is, upon witnessing its neighbour jump, the bystander suddenly looks scared as well. The bystander catches the fear of the demonstrator," says Rune Bruls, an author on the study. The reaction of the bystander influences how the demonstrator feels about the shock that happened to him. Bystanders that were less scared reduced the fear in their demonstrators. "Fear just jumps from one rat to another", explains Bruls. "That way a rat can prepare for danger before they even see it."

In humans, witnessing the pain of others activates a region between the two hemispheres that is also active when we feel pain on our own body. To see whether this region is the same in rats, the team injected a drug to temporarily reduce activity of this area. "What we observed, was striking: without the region that humans use to empathize, the rats were no longer sensitive to the distress of a fellow rat. Our sensitivity to the emotions of others is thus perhaps more similar to that of the rat than many may have thought," explains Professor Christian Keysers, the lead author of the study.

Another remarkable finding, is that empathy is independent from the fact whether you know the other. For rats that had never met each other, the emotions of the other rat were as contagious as for rats that had shared the same home for five weeks. "This really challenges our notions of the origin of empathy," says Valeria Gazzola, one of the senior authors of the study. Many believe that humans and animals are empathic, because if they are sensitive to the pains of their kids, it is good for Darwin fitness. This parental care then generalizes to empathizing with your closest friends. "What our data suggest, is that an observer shares the emotions of others because it enables the observer to prepare for danger. It's not about helping the victim, but about avoiding becoming a victim yourself," explains Gazzola.