That study reported that male fruit flies that were sexually rejected drank four times as much alcohol as fruit flies that mated with female fruit flies.
“Same reward center,” said Schwartz, “different way to get there.” Other chemicals at work during romantic love are oxytocin and vasopressin, hormones that have roles in pregnancy, nursing, and mother-infant attachment.
Dopamine activates the reward circuit, helping to make love a pleasurable experience similar to the euphoria associated with use of cocaine or alcohol.
Scientific evidence for this similarity can be found in many studies, including one conducted at the University of California, San Francisco, and published in 2012 in .
A 2011 study conducted at Stony Brook University in New York state found that it is possible to be madly in love with someone after decades of marriage.
The research team, which included Fisher, performed MRI scans on couples who had been married an average of 21 years.Her team analyzed 2,500 brain scans of college students who viewed pictures of someone special to them and compared the scans to ones taken when the students looked at pictures of acquaintances.Photos of people they romantically loved caused the participants’ brains to become active in regions rich with dopamine, the so-called feel-good neurotransmitter.More than 20 years ago, the biological anthropologist Helen Fisher studied 166 societies and found evidence of romantic love—the kind that leaves one breathless and euphoric—in 147 of them.This ubiquity, said Schwartz, an HMS associate professor of psychiatry at Mc Lean Hospital in Belmont, Mass., indicates that “there’s good reason to suspect that romantic love is kept alive by something basic to our biological nature.” In 2005, Fisher led a research team that published a groundbreaking study that included the first functional MRI (f MRI) images of the brains of individuals in the throes of romantic love.This circuit is considered to be a primitive neural network, meaning it is evolutionarily old; it links with the nucleus accumbens.Some of the other structures that contribute to the reward circuit—the amygdala, the hippocampus, and the prefrontal cortex—are exceptionally sensitive to (and reinforcing of) behavior that induces pleasure, such as sex, food consumption, and drug use.Richard Schwartz and Jacqueline Olds know a lot about love.These Harvard Medical School (HMS) professors and couples therapists study how love evolves and, too often, how it collapses.Many theories of love, said Schwartz and Olds, propose that there is an inevitable change over time from passionate love to what is typically called compassionate love—love that is deep but not as euphoric as that experienced during the early stages of romance.That does not, however, mean that the spark of romance is quenched for long-married couples.