For their study, the researchers conducted brain scans on 20 women as they provided moral support while their partners were given painful electric shocks. They found that women who comforted boyfriends, who were in pain, showed increased blood flow to areas of the brain associated with reward.
This was apparently triggered by the release of the feel -good chemical dopamine that is more usually associated with chocolate treats or sex, say the researchers.
When the women were not allowed to provide support, these same regions -- the ventral striatum and septal area -- showed decreased activity, the 'Daily Mail' reported.
Naomi Eisenberger, the study's co-author, said: 'The ventral striatum is typically active in response to simple rewards, such as chocolate, sex and money. It now seems likely that some of the health benefits of social support actually come from the support we provide to others.'
Suggesting that this rewarding effect may be evolutionary, she added: 'Giving support to those we are close to may increase their likelihood of survival.'
According to co-author Tristan Inagaki, one may think it would be more pleasurable to touch one's boyfriend when he is not going through something painful, 'but we found the opposite, which was surprising'.
The researchers suggest this rewarding effect may be evolutionary and could have helped humans ensure their families' survival.
Eisenberger added: 'Giving support to those we are close to, such as family members or children, may increase their likelihood of survival and, therefore, the likelihood that our genes will get passed on.'