Rats show empathy to trapped cage mates

CHICAGO, Dec. 9 (UPI) -- Rats can be empathetic and will help free a trapped cage-mate even in the absence of any reward for doing so, U.S. researchers report.

Helping others out of empathy has long been associated strictly with humans and other primates, but research led by the University of Chicago shows rats exhibit this prosocial behavior as well.

In the study laboratory rats repeatedly freed their cage-mates from containers without a clear reward for doing so, and the rodents didn't bother opening empty containers or those holding stuffed rats, The Christian Science Monitor reported Friday.

The findings show empathy and impulse to help others are common across other mammals, the study's lead author said.

"Helping is our evolutionary inheritance," neuroscientist Peggy Mason told LiveScience.com. "Our study suggests that we don't have to cognitively decide to help an individual in distress; rather, we just have to let our animal selves express themselves."

"When the free rat opens the door, he knows exactly what he's doing -- he knows that the trapped rat is going to get free," Mason said. "It's deliberate, purposeful, helping behavior."