Love is a drug, actually
The fragile and abundant eco-system of love has long fascinated, fulfilled and confounded humans.
The oldest known love poem was penned 4000 years ago and anthropologists have yet to find a society where the concept of love does not exist.
The magic of love arguably lies in its mystery. The fact is that despite algorithms or reducible sets of criteria, we cannot determine who we'll fall in love with. Love not only surprises us, but it has an alchemistic ability to shock and transform us.
Most of us have experienced love's rapture and its misery. In one study of American college students, 93 per cent of both sexes had been rejected by someone they really loved and 95 per cent had also rejected someone who really loved them.
So, it is not a surprise that there is a desire to understand and deconstruct love. But how does understanding the science help us and can it ever explain who we fall in love with?
Helen Fisher, a biological anthropologist and professor at Rutgers University, is among the world's most prominent experts in the field.
She has been studying love and attraction for more than 30 years and has written five books on the subject.
She doesn't believe that understanding the science behind love diminishes its magic. ''The bottom line is you can know every single ingredient in a chocolate cake but when you eat it you still feel the joy and the magic,'' she says. ''It's never lost the joy for me. Like a Ferrari - you know all the parts, but still feel the thrill.''
True, but this is a far more romantic take on the science of love than that of American psychology professor, Barbara Fredrickson.
Fredrickson's scientific stance, in her new book, Love 2.0: How Our Supreme Emotion Affects Everything We Feel, Think, Do, and Become is that there is no such thing as everlasting love.
Instead, she says (and try saying this to your sweetheart in a romantic moment) our concept of love is simply a ''micro-moment of positivity resonance''.
This idea doesn't resonate with Fisher, who asks me to repeat the phrase three times before dismissing it.
But she does acknowledge that there is a decidedly scientific and unromantic underlay to love.
''Romantic love is not an emotion, it is basically a drive that comes from a brain region far below emotion,'' says Fisher.
Love is a drive that happens in three parts, she explains. The first is lust, which is stimulated by the sex hormones testosterone and oestrogen and will ''get you out looking for anything''.
The second part is romantic love, which helps us focus our desire on one person and is driven by dopamine (also activated by cocaine and heroin) and serotonin - the so-called happy hormone. Finally, attachment is cultivated by oxytocin, the ''cuddle-hormone'' and vasopressin, an important chemical for commitment.
It's a chemical concoction that is enough to make us crazy. And it does. This is one of Fisher's most important findings.
''Love is a profound addiction,'' she says. ''This is important to know for people who can't walk out of a relationship. You've got to treat it as an addiction.''
While ''it's a pretty wonderful addiction when it's going well'', it helps explain some of the madness of being in love.
''Some [drives], like thirst and the need for warmth cannot be extinguished until satisfied,'' she says in Cut Loose: (Mostly) Older Women Talk About The End of (Mostly) Long-Term Relationships. ''The sex drive, hunger, and the maternal instinct can often be redirected, even quelled.
''Falling in love is evidently stronger than sex drive because when one's sexual advances are rejected, people do not kill themselves or someone else. Rejected lovers, on the contrary, sometimes stalk, commit suicide or homicide, experience severe depression, even physical pain.''
In fact the physical pain of a broken heart can kill us by suppressing our immune system, thus making us more susceptible to illness, research by the University of Birmingham and published last year in the journal Brain Behaviour and Immunity has showed.
Professor Janet Lord, who led the research, said at the time: ''There are a lot of anecdotes about couples who were married for 40 years when one of them passes away, and then the other dies a few days later. It seems there is a biological basis for this. Rather than dying of a broken heart, however, they are dying of a broken immune system. They usually get infections.''
None of this explains who we fall in love with though. And while Fisher has found, through her research, that we tend to fall in love with people of a similar standing in terms of appearance, wealth and status, ''timing, proximity and someone who seems mysterious'' also play a part.
''But, you can walk into a room where all the people are equal [to you] in intelligence, attractiveness, socio-economic status and you don't fall in love with all of them.''
This understanding led her to her second most important discovery; personality styles affect who we fall in love with. After a survey of 13 million people she came up with these four personality types: The Explorer, who is curious, creative, and spontaneous; The Builder who is calm, social, and good at managing people; The Director who is analytical, focused and decisive; and The Negotiator who is imaginative, intuitive, empathetic and emotionally expressive.
Like is attached to like, she found. Explorers like other explorers and builders like other builders, for instance.
There is one exception. Testosterone-driven directors tend to fall for ''high-oestrogen'' negotiators and vice versa.
But, pragmatic as all this may be ''there is magic to love'', Fisher insists.
''We're never going to know everything.''
Thank goodness for that.
Keep the flame alive
If you want to keep love, there are concrete tools to change your relationship for the better, Fisher says.
+Do novel things - that drives up the dopamine system.
+Stay in touch physically - hold hands, lie in your lover's arms. Touch drives up oxytocin.
+Say nice things to each other on a daily basis - positive illusion is the ability to look past the negative and accentuate the positive.