Mason lab uncovers empathy-driven helping behavior in rodents

The first evidence of empathy-driven helping behavior in rodents has been observed in laboratory rats that repeatedly free companions from a restraint, according to a new study by University of Chicago neuroscientists.

The observation, published in Science, places the origin of pro-social helping behavior earlier in the evolutionary tree than previously thought. Though empathetic behavior has been observed anecdotally in non-human primates and other wild species, the concept had not previously been observed in rodents in a laboratory setting.

“This is the first evidence of helping behavior triggered by empathy in rats,” said Jean Decety, the Irving B. Harris Professor of Psychology and Psychiatry. “There are a lot of ideas in the literature showing that empathy is not unique to humans, and it has been well demonstrated in apes, but in rodents it was not very clear. We put together in one series of experiments evidence of helping behavior based on empathy in rodents, and that’s really the first time it’s been seen.”

The study demonstrates the deep evolutionary roots of empathy-driven behavior, said Jeffrey Mogil, the E.P. Taylor professor in pain studies at McGill University, who has studied emotional contagion of pain in mice.

“On its face, this is more than empathy, this is pro-social behavior,” said Mogil, who was not involved in the study. “It’s more than has been shown before by a long shot, and that’s very impressive, especially since there’s no advanced technology here."

The experiments, designed by psychology graduate student and first author Inbal Ben-Ami Bartal with co-authors Decety and Peggy Mason, placed two rats that normally share a cage into a special test arena. One rat was held in a restrainer device — a closed tube with a door that can be nudged open from the outside. The second rat roamed free in the cage around the restrainer, able to see and hear the trapped cagemate but not required to take action.

The researchers observed that the free rat acted more agitated when its cagemate was restrained, compared to its activity when the rat was placed in a cage with an empty restrainer. This response offered evidence of an “emotional contagion,” a frequently observed phenomenon in humans and animals in which a subject shares in the fear, distress or even pain suffered by another subject.

(see Press Release)