Rats have empathy and avoid actions that can cause pain to fellow rodents — unless the reward is high enough, study shows
- Experts from the Netherlands presented rats with two treat-dispensing levers
- They let them pick a favourite lever then made that one give another rat a shock
- The rats would then change their preference to not harm their fellow rodent
- Yet if the shocking lever gave out three treats, the rats became more selfish
Rats have empathy and avoid actions that can cause pain to fellow rodents — unless the reward is high enough, a study has found.
Harm aversion — avoiding actions that hurt others — is seen as an important part of moral development in humans, but is reduced in violent, antisocial individuals.
Researchers believe that their findings in rats might help scientists to develop drug treatments to increase harm aversion in patients who show psychopathic behaviour.
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Rats have empathy and avoid actions that can cause pain to fellow rodents — unless the reward is high enough, a study has found
The research was undertaken by Christian Keysers and colleagues at the Netherlands Institute for Neuroscience in Amsterdam.
‘We share a mechanism that prevents antisocial behaviour with rats, which is extremely exciting to me,’ Professor Keysers said.
‘We can now use all the powerful tools of brain science to explore how to increase harm aversion in antisocial patients.’
To investigate harm aversion in rats, the researchers gave the rodents a choice between two levers that they could press to receive sugary treats.
Once the animals had developed a preference towards one of the two levers, the scientists reconfigured the system so that the favourite lever would cause a rat in the next cage to receive an unpleasant shock when a treat was being dispensed.
The researchers found that, when they realised that the lever was causing their fellow rodent harm, the rats would decrease their use of it.
‘Much like humans, rats actually find it aversive to cause harm to others,’ said paper author and neuroscientist Julen Hernandez-Lallement.
When the favourite lever was made to dispense two treats at once, the rats still avoided it for the sake of their counterpart — but became more selfish when the reward increased to three treats instead.
Harm aversion — avoiding actions that hurt others — is seen as an important part of moral development in humans, but is reduced in violent, antisocial individuals
The researchers then scanned the brains of the rats, finding that a region of the brain known as the ‘anterior cingulate cortex’ was becoming active during the test.
This same brain region has also been found to light up in people when they are empathising with the pain of others.
When the researchers used a local anaesthetic to reduce brain activity in the rats’ anterior cingulate cortices, the team found that the rodents ‘stopped avoiding harming fellow rats for sweet treats.’
Researchers believe that their findings in rats might help scientists to develop drug treatments to increase harm aversion in patients who show psychopathic behaviour
‘That humans and rats use the same brain region to prevent harm to others is striking,’ said paper author and neuroscientist Valeria Gazzola.
‘It shows that the moral motivation that keeps us from harming our fellow humans is evolutionary old, deeply ingrained in the biology of our brain and shared with other animals.’
The full findings of the study were published in the journal Current Biology.
HOW SMART ARE RATS?
Rats are considered highly social animals that become attached to each other, love their families and can bond with their human owners.
It is believed they are capable of empathy and can recognise and react to pain in others.
A study by Jaak Panksepp, a neuroscientist at Bowling Green State University, found when rats are tickled they make chirping sounds that are similar to human laughter.
‘[Y]oung rats have a marvellous sense of fun’, said Dr Panksepp, adding that the rodents bonded with the human tickler and liked to be ticked as much as possible.
Contrary to their reputation they are also very clean animals and groom themselves regularly.
Rats are highly social animals that become attached to each other, love their families and can bond with their human owners
In September last year researchers from New York University found when rats are frightened in the day, the fear centres in their brains are re-activated during sleep – potentially helping to strengthen memories.
Researchers say that rats store maps of what they experience in both of their hippocampi – two curved structures inside the brain.
Different places that the rat experiences are processed by different groups of neurons that activate together in sequence as a rat runs around a maze.
After exploring an area, these sequences have been observed replaying as the rat sleeps – comparable to dreaming of the paths they’d taken when they were awake.
Researchers believe that this allows memories to be stored in the long term.
The most recent research by the University of St Andrew’s found rats help each other out in return for favours in a similar way to humans.
The rodents were found to groom food-providers more often than partners who had refused to help.
In addition, common Norway rats offered more food to those who cleaned them, researchers found.