Scientists may have discovered the real reason why Sandy was so hurt when Danny snubbed her after their summer of loving - her broken heart may have been genuinely painful.
Researchers have found a genetic link between physical pain and social rejection, which means the good-girl character in Grease may have found breaking up with her holiday romance truly excruciating.
Psychologists at the University of California studied the gene responsible for regulating the body's most potent painkillers, known as mu-opioids.
Painful: Scientists have identified that the gene responsible for regulating the body's painkillers is also involved in sensitivity to unpleasant social experiences
They found that people with a rare variation of the mu-opoid receptor gene, OPRM1, were more sensitive to rejection and experience more brain evidence of distress than those with the more common form.
Study co-author Prof Naomi Eisenberger said: 'Individuals with the rare form of the pain gene, who were shown in previous work to be more sensitive to physical pain, also reported higher levels of rejection sensitivity and showed greater activity in social pain-related regions of the brain when they were excluded.'
Researchers collected saliva samples from 122 participants to assess which form of the OPRM1 pain gene they had and then measured sensitivity to rejection in two ways.
First, participants completed a survey that measured their own sensitivity to rejection. They were asked how much they agreed or disagreed with statements such as: 'I am very sensitive to any signs that a person might not want to talk to me.'
Then the emotions of 31 people among the group were tested when they were excluded during a virtual ball-tossing computer game. Those with the rare variation of the gene felt more distress when they were left out of the game compared to the others.
Co-author Baldwin Way said: 'These findings suggest that the feeling of being given the cold shoulder by a romantic interest or not being picked for a schoolyard game of basketball may arise from the same circuits.'
This is the first time that it has been proved that genes involved in physical pain are linked to mentally-painful times like social rejection and breaking up with a lover.
Prof Eisenberger said this overlap in the neurobiology of physical and social pain makes perfect sense.
'Because social connection is so important, feeling literally hurt by not having social connections may be an adaptive way to make sure we keep them,' she said.
'Over the course of evolution, the social attachment system, which ensures social connection, may have actually borrowed some of the mechanisms of the pain system to maintain social connections.'
The research is published by the Proceedings of the National Academy of Sciences.
Ref: dailymail.co.uk
