North American prairie vole 'shows consoling traits towards distressed friends'
A small fluffy rodent from North America displays genuine empathy if it sees a friend or relative in distress, say scientists.
The prairie vole is capable of consoling behaviour that previously has only been known in humans and a few higher animals, such as chimpanzees.
Its caring nature is based on the "cuddle" hormone oxytocin, which promotes maternal nurturing and social bonding, researchers discovered.
The findings are said to have implications for understanding and treating conditions that disrupt our ability to respond to the emotions of others, such as autism and schizophrenia.
Dr Frans de Waal, a member of the team from Yerkes National Primate Research Centre at Emory University in the US, said: "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."
In 1979 Dr de Waal showed that chimpanzees provide contact comfort to victims of aggression.
The new study is the first to demonstrate altruistic consolation outside of large-brained species.
In the experiment, prairie voles who were relatives and "friends" were temporarily separated while one was exposed to mild electric shocks.
When they were reunited, the non-stressed voles comforted their upset companion with a lot of licking. The same behaviour was not seen when no electric shock was applied to any of the separated voles.
Consoling behaviour was not seen when the stressed vole was a stranger. Tests showed that it was driven by oxytocin, said the researchers writing in the journal Science. When oxytocin signalling was blocked, the animals no longer consoled others in distress.
Co-author Dr Larry Young, also from Yerkes, said: "Many complex human traits have their roots in fundamental brain processes that are shared among many other species.
"We now have the opportunity to explore in detail the neural mechanisms underlying empathetic responses in a laboratory rodent with clear implications for humans."