LAB RATS will look out for one another, helping a cage mate to escape a restraint in what researchers say is the first evidence of empathy among rodents.
The rats helped one another, forsaking food in favour of doing the other a good turn.
Empathetic behaviour – being able to understand and share the feelings of another – has long been observed in primates but not until now in rodents.
Researchers from the University of Chicago showed how one rat helped another even though lending assistance did not win any reward.
The researchers set up a cage that included a restraint: a closed tube with a door that could be opened from outside.
They put one rat in the restraint and the other was free to roam about the cage.
Initially the free rat exhibited “emotional contagion”, a common condition in humans and animals where one shares the fear or distress seen in another.
It shows this shared response by freezing or by running about helplessly.
The free rat calmed down, however, and then went to work on the door, soon learning how to open it to free its cage mate. From then on the rat acted immediately to liberate its partner in what the researchers described as “empathy-driven helping behaviour”.
The rat would release its friend even if not allowed to socialise afterwards, something the rats would consider as a reward, the scientists say in their findings, published this morning in the journal Science.
The generous rat extended this kindness even when tempted with a pile of chocolate.
It would free its cage mate first before sharing the treat, even though it could have gobbled the goodies up before releasing the other.
“There was no other reason to take this action except to terminate the distress of the trapped rats,” said lead author Inbal Ben-Ami Bartal.
The fact the rodents repeated the behaviour “basically means that this action is rewarding to the rat”.
Early results showed females were slightly more likely to be a “door opener” than the males.
The findings also suggest that pro-social helping behaviour occurs earlier in the evolutionary tree than previously thought.