Rats’ selflessness in study surprises researchers

WASHINGTON – Rats don’t always act like, well, rats.

New experiments show rats demonstrating compassion and helping other rodents. It’s a trait some scientists thought was reserved only for humans and higher primates.

And it’s certainly not the sneaky, selfish rap that goes with calling someone a dirty rat.

In repeated tests, rats freed another trapped rat in their cage, even when yummy chocolate served as a tempting distraction. Twenty-three of the 30 rats opened the trap by pushing in a door. The rats could have gobbled the chocolate before freeing their partners, but often didn’t, choosing to help and share the goodies.

“Basically they told us (freeing another rat) is as important as eating chocolate,” said study author Peggy Mason of the University of Chicago. “That’s a very striking thing.”

In some cases, the rats first took the chocolate chips out of a container, but didn’t eat them, then freed the other rat and shared “almost as if they were serving them chocolate,” Mason said. The research was reported in the journal Science on Thursday.

Also, females showed more consistent empathy than males, Mason said. All six females freed their trapped partner; 17 of the 24 males did so. This confirms other studies that show females demonstrating more pro-social behavior than males, she said.

There were days when the male rats took the day off from helping their trapped partner, but the females never did, she said.