Jun 30, 2006, 3:54 GMT
Washington - The human ability to sense another person's pain has been detected in mice studied by researchers in Canada, the journal Science reported Thursday.
The team of scientists led by professor Jeffrey Mogil found that mice reacted to the pain of other small rodents as long as they were familiar with them and felt pain themselves at the same time.
The findings show for the first time that empathy can connect animals as primitive as mice. Empathy is seen almost exclusively as a human attribute and one of the clearest ways of distinguishing people from animals.
Mogil and his colleagues at McGill University in Montreal conducted experiments in which pain was inflicted on laboratory mice. In one, mice were injected in the belly with a weak acid solution, causing them to stretch repeatedly and extend their back legs.
The researchers found when two mice were injected side by side, they spent more time writhing than when they were injected alone. This only happened, however, when they had lived with the other mice together for at least a week.
A similar result occurred when mice were injected with formalin in one paw. The animals appeared to react to their cage mates' pain in the time they spent licking the painful area.
The scientists say the research could be relevant to understanding human pain.
'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 by those around us?' Mogil said at Science's website Thursday. The research will be published Friday in the journal.
Frans de Waal, professor of primate behaviour at Emory University in Atlanta and director of the Living Links Center at the Yerkes National Primate Research Center, said the reaction of the mice were true expressions of empathy. They are adjusted to one another, he said, and have a certain ability to sense pain experiences of fellow mice.
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