Last term, my lab went to the Corpus Playroom to see The Effect. This was ideal entertainment for our group of researchers, being a mixture of romance, drama, and neurobiology. Two people are enrolled in a clinical trial of a new antidepressant and fall passionately in love – but are their feelings real, or just a side effect of altered brain activity?

The play’s answer was, predictably, the former. More generally, though, implying that ‘mere’ biochemistry has nothing to do with true love rather misses the point. There’s a joke about a sensitive neuroscientist who got engaged: she stuck her head in a brain scanner and presented the results at the altar, saying “I do, and here’s proof!” (The point being, of course, that for neuroscientists, measurable changes in brain activity or hormones are as real as you can get.) Finding out whether love has a neurological basis should not devalue our experiences of romance, and as a sensitive neuroscientist myself, I’m honour-bound to suggest that it actually enriches them.

Jokes aside, do our brains really light up when we’re in the throes of a new romance? According to functional MRI studies, they do. Some of the best-known work was done in 2005 by Helen Fisher and colleagues, and involved university students who had recently fallen in love. Fisher’s team collected brain scans while each student contemplated photographs of their beloved, then compared them to scans taken while the students looked at pictures of neutral acquaintances. The major brain areas with increased romantic activity were part of the brain’s reward system, a set of interconnected regions that help us recognise and pursue pleasurable stimuli.

‘Pleasurable stimulus’ might not be a poetical description of one’s newfound fleet-footed, tall, dark, handsome love interest, but it is somewhat accurate. It also helps explain why new romances can border on obsession, and why break-ups hurt so much: since the brain circuitry overlaps with neural mechanisms controlling addiction, depriving someone of their romantic ‘reward’ effectively puts them through devastating withdrawal symptoms. This doesn’t mean love should be treated like alcoholism – notwithstanding the 2012 Science paper showing that sexually deprived male flies consume more alcohol than satiated ones! Instead, this knowledge could make us more forgiving of others who can’t stop talking about their amazing new partners (even if we are sick of hearing about them). More seriously, understanding the mechanics of love and rejection could also help protect potential victims of jealousy, abuse, or crimes of passion.

No discussion of romantic chemistry would be complete without oxytocin – touted as the ‘cuddle chemical’ – and vasopressin. These hormones came to fame through early studies on monogamous rodents called prairie voles. In these animals, activity in brain regions detecting oxytocin (for females) or vasopressin (males) goes up after mating and predicts how faithful a pair will be; blocking oxytocin or vasopressin increases promiscuity. In humans, oxytocin is implicated in both maternal and romantic bonding, but its precise role is less clear.

Unfortunately, the media frenzy over oxytocin also has a dark side. Some is exaggeration: if we believe the headlines, a squirt of oxytocin spray cures everything from marital breakdown to anorexia. Some is dishonest: abstinence-only sex educators sometimes misquote data ‘proving’ that women should save their oxytocin response for marriage, lest they be irreversibly traumatised by pair-bonding with too many people. This ignores oxytocin’s inconvenient habit of showing up in all kinds of human interactions unrelated to sex or childrearing, including non-romantic touch, and all kinds of emotions, such as fear and envy. The lesson? Love is scientifically complicated; cherry-picking data is bad science.

At this point, die-hard romantics will probably complain that brain scans and biochemistry take all the mystery out of love. Pragmatists might counter that mystery is damnably unhelpful when deciding whether to spend the rest of your life with that special someone. Now, if you’ll excuse me, I’ve got a hot date with my boyfriend and an MRI scanner.