Social rodents show empathy just like humans: study

Social laboratory rodent, the prairie vole, shows empathy when other voles are distressed, scientists have found, contradicting the belief that acting to relieve sadness of others is uniquely human.
Researchers at the Yerkes National Primate Research Centre at the Emory University in US have for the first time shown consolation behaviour in rodents.
They demonstrated that oxytocin - a brain chemical well-known for maternal nurturing and social bonding - acts in a specific brain region of prairie voles, the same as in humans, to promote consoling behaviour.
Prairie voles are small rodents known for forming lifelong, monogamous bonds and providing bi-parental care of their young.

Consolation is defined as calming contact directed at a distressed individual; for example, primates calm others with a kiss and embrace, whereas voles groom others.
The prairie voles' consoling behaviour was strongest toward familiar voles, and was not observed in the closely related, but asocial, meadow vole.

The findings have important implications for understanding and treating psychiatric disorders in which detecting and responding to the emotions of others can be disrupted, including autism spectrum disorder (ASD) and schizophrenia.
"Scientists have been reluctant to attribute empathy to animals, often assuming selfish motives. These explanations have never worked well for consolation behaviour, however, which is why this study is so important," said Frans de Waal from Emory University.

Researchers tied consolation to maternal nurturing mechanisms in the brain, which suggests empathy, not complex cognition, is key.
Observing another animal in distress caused activation in the anterior cingulate cortex, a brain region that is also activated when humans see another person in pain.
Prairie voles responded by increasing their pro-social contact, which clearly reduced the other's anxiety.
When the researchers blocked oxytocin signalling specifically in the anterior cingulate cortex of prairie voles, the animals no longer consoled others in distress.
Consoling behaviour evolved in the context of prairie voles' monogamous social structure by tweaking brain systems involved in maternal nurturing, which are present in all mammals, researchers said.

The findings were published in the journal Science.