The Science of Love

By Richard Asa @RickAsa
March 16, 2016

Brain chemicals and nerve signals may lie at the heart of the heart.

To most people love may seem mystical or abstract, a matter of fate, chance and irrational compulsion

But, there’s a science to it. Clinically speaking “there are three phases to falling in love” with different hormones in play at each stage, says a BBC report.  

“Events” that occur in the brain when you’re in love are similar to what occurs in mental illness. Depending on what has transpired over the course of your romantic relationships, you might readily agree. 


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Your attraction to someone could occur because you like their genes, if not their jeans. You may also like their smell as much as their looks when it comes to the “fanciability factor,” the BBC report says. This would explain the sheer size of perfume and cologne departments.

Science can even determine whether a relationship will last. 

We fall in love in three stages based on our biochemistry, believes Helen Fisher, a biological anthropologist at Rutgers University, author, and chief scientific advisor to the dating site Each involves different chemicals. 

She studies the “anatomy of love” with Lucy Brown, PhD, clinical professor in neurology at New York’s Einstein College of Medicine. 

Through their joint research, they theorize that the first stage is lust. Driven by the sex hormones testosterone and estrogen, men and women are programmed to seek “a range of potential mating partners.” 

“After all, you can have sex with someone you aren’t in love with. You can even feel the sex drive when you are driving in your car, reading a magazine or watching a movie. Lust is not necessarily focused on a particular individual,” they write. 

Put another way, these hormones “get you out looking for anything,” Fisher says. 

Romantic love, or attraction, comes next. This is that feeling of being thunderstruck. You have obsessive thinking about and “craving” for a particular person. 

The brain chemicals involved in this phase are “monoamines,” including dopamine, norepinephrine (adrenalin), and serotonin. The last is “one of love’s most important chemicals and may drive us temporarily insane,” says the BBC report. 

The third phase, attachment, takes over after the heady few years of attraction fade. This is a long-lasting commitment that keeps couples together long enough to reproduce. From the standpoint of evolution, that’s the whole purpose. 

Two hormones, oxytocin and vasopressin, are important in this stage, Fisher and Brown say. 

Oxytocin is released by both sexes during orgasm and is thought to promote bonding during intimacy. “The theory goes that the more sex a couple has, the deeper their bond becomes,” according to the BBC report. 


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Vasopressin helps control the kidneys. Its role in long-term relationships was discovered when researchers studied the prairie vole. 

These voles are essentially sex maniacs who indulge far more than they need to for reproduction. When male prairie voles were given a drug that suppressed the effect of vasopressin, the bond with their partner “deteriorated immediately” and they lost their devotion. 

University of Miami philosophy professor Birgit Brogaard uses Valentine’s Day as an example to explain the science of love another way. 

“There are exceptions, of course, but Valentine’s is much more central to women,” she tells the Miami Herald. “Anecdotally, I hear more men speaking negatively about Valentine’s, while women are more excited.”

The reason is that women place more value on relationships, even as they climb the career ladder or achieve other measures of success that are traditionally male. “We have this tendency for women to need validation from men,” Brogaard says. 

She adds that as irrational as love may seem, crazy emotions and all, it’s a choice. All humans can decide to start it or end it. It can be biologically and behaviorally controlled, she believes. 

All the emotions comprising love and the brain chemicals that control them are present all the time. The reason a close friend of hers went from lovelorn to disgusted in a heartbeat, Brogaard writes, is because positive emotions dominated nerve signals in her friend’s brain for a long time. Then, at the moment of epiphany after another blow-off, her friend’s negative nerve signals underlying negative emotions — which had been suppressed — switched on and those emotions “became strong enough for her to consciously experience her negative reactions,” Brogaard writes in her book “On Romantic Love: Simple Truths About a complex Emotion.” 

“This explanation of the swift change in Zoe’s condition presupposes that there are unconscious emotions, brain events that guide our behavior and thought processes but do not correlate with conscious experience,” Brogaard says. 

Love and hate, she adds, are among emotions that often are not “consciously manifested. They involve nerve signals in the brain that are too weak to give rise to conscious experience. But they can affect our behavior, thoughts and reasoning processes; they can affect our daily lives.”

In that way, the philosopher in Brogaard takes the uncontrollable chemicals out of the equation, lumps love in with other emotions, and claims anyone can maintain rationale control over it. 

“Love, too, is something we can choose,” she writes. “We can take measures to fall out of love” as well. 


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April 02, 2020

Reviewed By:  

Janet O’Dell, RN