Empathetic mice feel each other’s pain

It was a crisp autumn morning, the kind we get in Montreal two weeks before the winter freeze. The stairs were glistening with dew, and as I enthusiastically took them underfoot, I felt myself slip. And down I went, my tailbone crashing on each concrete step, leaving me bruised and discouraged.

As you read of my unfortunate tumble, playing it out in your mind’s eye, you probably understood and even felt some of my pain: this feeling is empathy. Empathy means to feel into another, derived from the Greek words em, meaning into and pathos, meaning to feel. How an individual could accurately replicate the emotions of another is more than a question of philosophy, however, it is also a question of neurology.

Years ago, psychologist William James discovered that the same emotional circuits in the brain are activated when experiencing a particular emotion as when enacting the physical reactions to these emotions. Smiling can induce feelings of happiness. Quickening your breath can lead to feelings of anxiety. Studies also found similarities between the brain activity of subjects viewing particular facial expressions, and those who were actually exhibiting those expression. Other studies showed that seeing a loved one in pain, and having pain inflicted on them, activated some of the same areas of the pain circuit.

Recently, Dr. Jeffrey Mogil, McGill Psychology professor has shown that emotional contagion – recognizing and reacting to pain in one’s peers – also occurs in mice. Mice writhe and lick their paws in response to viewing another mouse in pain.

“The mice seem hardwired to form a lower type of empathy, emotional contagion,” Mogil said in an interview with the CBC.

The empathetic mouse responds more intensely if the mouse being subjected to pain had been a cage-mate of two weeks than if it was an unknown mouse. Perhaps even more interestingly, the pain sensitivity of a mouse increases while it witnesses a social ally in pain, suggesting that the mouse actually feels the pain of its peer. This effect occurred even when the two mice were experiencing different types of pain: one responding to the pain of a heated floor and the other experiencing an artificially induced nausea.

“This is the most striking part to me,” Mogil told The New York Times, “that simply looking at an animal in one type of pain makes you sensitive to another kind of pain in a different part of your body; that this social manipulation of pain sensitizes the whole pain system.”

This automatic mechanism is of great value for survival. Mammals, as opposed to other types of animals, give birth to young that are very vulnerable. Frans de Waal, a Psychology professor at Emory University has speculated that being in tune with the emotions of their young may help mothers take better care of their offspring; empathy allows the mother to better understand and answer their distresses. It is also beneficial for social animals like mammals to extend this empathy to other members of their social group and thus strengthen community ties and loyalties.

This emotional contagion isn’t triggered by conscious concern or identification with another, however, which is the difference between animal and human empathy. Human beings take this evolutionary tradition a step further, adding a level of conscious awareness. Humans actually understand that they are feeling another’s emotions. So the next time you take one of those excruciating and embarrassing trips down the slippery stairs, know that you’re not alone.