Rats to the rescue as they prove they've human-like feelings
Rats display human-like empathy and will unselfishly go to the aid of a distressed fellow rodent, research has shown.
The results of an experiment in which rats opened a door to free trapped cage-mates astonished scientists.
No reward was needed and not even the lure of chocolate distracted the rescuing rats.
"This is the first evidence of helping behaviour triggered by empathy in rats," said US study leader Professor Jean Decety.
"There are a lot of ideas in the literature showing that empathy is not unique to humans, but in rodents it was not very clear."
The study, conducted at the University of Chicago, involved placing two laboratory rats which normally share a cage in a test arena.
One rat was held in a closed tube with a door that could only be nudged open from the outside. The second was allowed to roam free outside the clear plastic tube, able to see and hear its trapped cage-mate.
Once the free rat learned by trial and error how to free its companion, it did so almost immediately.
No attempt was made to liberate a stuffed toy rat placed in the tube, and empty tubes were left unopened. But rats were freed even when they remained separated from their rescuers, ruling out socialisation as a reward factor.
Most strikingly, rats still prioritised their cage-mates when offered the option of "freeing" chocolate from a second tube.
The door to the trapped animal was just as likely to be opened first as the door providing access to the chocolate.
"That was very compelling," said co-author Professor Peggy Mason.
"It said to us that essentially helping their cage-mate is on a par with chocolate. He can hog the entire chocolate stash if he wanted to, and he does not. We were shocked."
The research is reported today in the journal 'Science'.