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The science of love


When do you know if you fancy someone? What does love do to your brain chemicals, and is falling in love just nature's way to keep our species alive?


We call it love. It feels like love. But the most exhilarating of all human emotions is probably nature’s beautiful way of keeping the human species alive and reproducing.


With an irresistible cocktail of chemicals, our brain entices us to fall in love. We believe we’re choosing a partner. But we may merely be the happy victims of nature’s lovely plan.


It’s not what you say...

Psychologists have shown it takes between 90 seconds and 4 minutes to decide if you fancy someone.

Research has shown this has little to do with what is said, rather

  • 55% is through body language

  • 38% is the tone and speed of their voice

  • Only 7% is through what they say


The 3 stages of love

Helen Fisher of Rutgers University in the States has proposed 3 stages of love – lust, attraction and attachment. Each stage might be driven by different hormones and chemicals.


Stage 1: Lust

This is the first stage of love and is driven by the sex hormones testosterone and oestrogen – in both men and women.


Stage 2: Attraction

This is the amazing time when you are truly love-struck and can think of little else. Scientists think that three main neurotransmitters are involved in this stage; adrenaline, dopamine and serotonin.



The initial stages of falling for someone activates your stress response, increasing your blood levels of adrenalin and cortisol. This has the charming effect that when you unexpectedly bump into your new love, you start to sweat, your heart races and your mouth goes dry.



Helen Fisher asked newly ‘love struck’ couples to have their brains examined and discovered they have high levels of the neurotransmitter dopamine. This chemical stimulates ‘desire and reward’ by triggering an intense rush of pleasure. It has the same effect on the brain as taking cocaine!


Fisher suggests “couples often show the signs of surging dopamine: increased energy, less need for sleep or food, focused attention and exquisite delight in smallest details of this novel relationship” .



And finally, serotonin. One of love's most important chemicals that may explain why when you’re falling in love, your new lover keeps popping into your thoughts.

Does love change the way you think?
A landmark experiment in Pisa, Italy showed that early love (the attraction phase) really changes the way you think.


Dr Donatella Marazziti, a psychiatrist at the University of Pisa advertised for twenty couples who'd been madly in love for less than six months. She wanted to see if the brain mechanisms that cause you to constantly think about your lover, were related to the brain mechanisms of Obsessive-Compulsive Disorder.


By analysing blood samples from the lovers, Dr Marazitti discovered that serotonin levels of new lovers were equivalent to the low serotonin levels of Obsessive-Compulsive Disorder patients.


Love needs to be blind

Newly smitten lovers often idealise their partner, magnifying their virtues and explaining away their flaws says Ellen Berscheid, a leading researcher on the psychology of love.


New couples also exalt the relationship itself. “It's very common to think they have a relationship that's closer and more special than anyone else's”. Psychologists think we need this rose-tinted view. It makes us want to stay together to enter the next stage of love – attachment.


Stage 3: Attachment

Attachment is the bond that keeps couples together long enough for them to have and raise children. Scientists think there might be two major hormones involved in this feeling of attachment; oxytocin and vasopressin.


Oxytocin - The cuddle hormone


Oxytocin is a powerful hormone released by men and women during orgasm.

It probably deepens the feelings of attachment and makes couples feel much closer to one another after they have had sex. The theory goes that the more sex a couple has, the deeper their bond becomes.

Oxytocin also seems to help cement the strong bond between mum and baby and is released during childbirth. It is also responsible for a mum’s breast automatically releasing milk at the mere sight or sound of her young baby.


Diane Witt, assistant professor of psychology from New York has showed that if you block the natural release of oxytocin in sheep and rats, they reject their own young.


Conversely, injecting oxytocin into female rats who’ve never had sex, caused them to fawn over another female’s young, nuzzling the pups and protecting them as if they were their own.



Vasopressin is another important hormone in the long-term commitment stage and is released after sex.


Vasopressin (also called anti-diuretic hormone) works with your kidneys to control thirst. Its potential role in long-term relationships was discovered when scientists looked at the prairie vole.


Prairie voles indulge in far more sex than is strictly necessary for the purposes of reproduction. They also – like humans - form fairly stable pair-bonds.


When male prairie voles were given a drug that suppresses the effect of vasopressin, the bond with their partner deteriorated immediately as they lost their devotion and failed to protect their partner from new suitors.


And finally … how to fall in love

  • Find a complete stranger.

  • Reveal to each other intimate details about your lives for half an hour.

  • Then, stare deeply into each other’s eyes without talking for four minutes.


York psychologist, Professor Arthur Arun, has been studying why people fall in love.

He asked his subjects to carry out the above 3 steps and found that many of his couples felt deeply attracted after the 34 minute experiment. Two of his subjects later got married.