Mice can feel empathy, say scientists
Empathy, the quintessentially human ability to sense another's pain,
been detected in mice.
Scientists found that mice were more sensitive to pain when they could
see other animals suffering at the same time.
The findings show for the first time that "emotional contagion" -
empathy, albeit in a very rudimentary form - can even connect animals
low on the evolutionary scale as mice.
For centuries empathy has been seen as a noble human attribute, and
of the clearest ways of distinguishing us from animals.
Experts still disagree on whether chimpanzees, let alone mice, are
capable of empathy.
The new study, conducted by Professor Jeffrey Mogil and colleagues at
McGill University in Montreal, Canada, involved a series of
in which pain was inflicted on laboratory mice.
In one, mice were injected in the belly with a weak acid solution.
Mice react to the injection by stretching repeatedly and extending
The research showed that when two mice were placed together in a
Plexiglas cylinder, they spent more time writhing than when they were
This only happened, however, when the mice were cagemates who had
together for at least a week.
A similar result occurred with mice injected with formalin in one paw.
The animals appeared to react to their cagemates in the time they
licking the painful area.
In the most significant experiment, scientists recorded the time it
for a mouse to lift its paw from a hot spot on the floor of the test
Mice withdrew their paws more quickly when at the same time they
observed a cagemate in pain from an acid injection.
It was clear in this case that the mice were not simply imitating what
other mice were doing.
"These data suggest that the pain system is sensitised in a general
manner by the observation of pain in a familiar," the researchers
reported in the journal Science.
Animal welfare campaigners might disapprove of the research. But the
scientists point out that as well as shedding new light on the
of animals, it could be relevant to understanding human pain.
Prof Mogil said: "Since we know that social interaction plays an
important role in chronic pain behaviour in humans, then the mechanism
underlying such effects can now be elucidated; why are we so affected
those around us?"
Dr Tania Singer, a cognitive neuroscientist at the University of
in Switzerland, questioned whether the mice really displayed empathy
the human sense.
She told Science: "Philosophers would argue you can only have empathy
you have consciousness.
"Psychologists would want to see evidence of altruistic behaviour and
Dr Peggy Mason, a neurobiologist at the University of Chicago, used
term "emotional contagion" - a primitive kind of empathy that does not
require understanding of what others are experiencing.
"Emotional contagion means one baby starts crying and all the babies
start crying," she said. "The second baby doesn't have to realise that
the first baby is upset because it has a dirty diaper."