Researchers from the University of Southern California examined activity in the 'pain matrix' of the brain, which activates when a person watches another suffer.
Humans feel the pain of their enemies more strongly than the discomfort of their friends - because that is when their opponents are most dangerous and unpredictable, scientists claim.
While many people might assume that they would empathise most with those they care about, a study has found that the opposite is true and the reason is one of self preservation as humans need to understand why an enemy is in pain to rule out the risk of retribution.
U.S. scientists discovered the part of the brain that is associated with empathising with the pain of others is activated more strongly by watching the suffering of hated enemies.
By SARAH GRIFFITHS
Via Edwin Rutsch