Prairie voles - also known as social rodents - console loved ones who are feeling stressed, says a study, suggesting that empathy is more common in animals than previously thought.
According to researchers from Emory University, this may be because of the effect of "love hormone" oxytocin in them.
Until now, consolation behaviour has only been documented in a few non-human species with high levels of sociality and cognition such as elephants, dolphins and dogs.
Prairie voles are particularly social rodents, causing them to be the focus of many studies.
For the study published in the prestigious journal Science, James Burkett and colleagues created an experiment where relatives and known rodent individuals were temporarily isolated from each other while one was exposed to mild shocks.
Upon reunion, the non-stressed prairie voles proceeded to lick the stressed voles sooner and for longer durations, compared to a control scenario where individuals were separated but neither was exposed to a stressor.
Consoling behaviour occurred only between those who were familiar with each other -- including non-kin members -- but not strangers.
Since the oxytocin receptor is associated with empathy in humans, the researchers blocked this neurotransmitter in prairie voles in a series of similar consolation experiments.
Blocking oxytocin did not cause family members and friends to alter their self-grooming behavior, yet they did cease consoling each other.
These findings provide new insights into the mechanisms of empathy and the evolution of complex empathy-motivated behaviours.
