Although we might lust with our eyes, we tend to love with far more body parts than that. There’s a whole factory of hormones produced in the brain that in turn affects our entire bodies, filling us up with that wonderful, indescribable feeling of devotion and exhilaration. We may localise these feelings to our mind, which is busy conjuring up glowing mental images of our beloved; our hearts, bursting with contentment; or our stomachs, which seem to become an anticipatory organ rather than a digestive apparatus. But if we were to take a look from the inside we would see a happy chemical concoction coursing through your blood, perfusing your brain, organs and tissues – even your big toe.
The reasons we fall for someone are complex and highly individualised. Initially you may be driven by oestrogen or testosterone – or both. Testosterone is the major driver of sexuality in men and women, but men carry a healthy dose of oestrogen also (though its role in the body is more subtle). These sex hormones help us to make first-impression appraisals of a potential mate, along with their non-verbal behaviours of body language and tone of voice. This stage, occurring mainly at a subconscious level, can take just a few seconds – and bam! Just like that, you’ve completely evaluated how attracted you are to someone.
Serious attraction, meaning that which goes beyond casual lust, causes your body to produce the neurotransmitters that we generally associate with exhilaration and a lack of physical pain. Neurotransmitters are the microscopic messengers in our nervous system that physically travel and communicate with one another in order to send messages to and from the central nervous system. Dopamine, adrenaline and serotonin are the main players when you can think of little else but your sweetheart’s face.
Adrenaline is normally produced when we have a stress response, but it can also indicate excitement – think about how you feel on a theme park ride (assuming it’s not just sick) – you might sweat, your heart will beat faster and your mouth will feel dry. If we took a closer look, we might expect to find your blood pressure has increased, your breathing has quickened and your startle response is more finely attuned. It’s stress of the very best kind.
Dopamine is perhaps the most pleasant of the body’s chemicals, so it’s hardly surprising that its effect on the brain is nearly identical to a cocaine high (though far safer). People in the midst of a dopamine rush will experience an increase in energy, a decreased need for sleep and have heightened, focused attention – generally just enough for one another.
Scientists believe that serotonin is linked to both neuroticism and certain sexual behaviours. Ever wonder why new love sometimes feels like obsession? One researcher studied people who had recently fallen in love and found their serotonin levels to be more comparable to people with obsessive compulsive disorder than to people who were not in love.
After all that excitement and pure elation, why on earth would we stick around when it begins to wane? Surely the natural tendency is to seek out the next person who leaves us lovestruck? While we can’t speak for everybody (because some of us undeniably get stuck at this point), the majority feel driven to form an attachment to their companion. There is good evidence that the hormones oxytocin and vasopressin are at work. You’ve probably heard of oxytocin as a bonding hormone in a different context – new mothers have a surge of it after giving birth. But it also plays an important role for both genders in driving us to form social groups, be a responsible parent and, of course, settle down with a mate. It helps, then, that a healthy dose of it kicks in just after orgasm.
You wouldn’t imagine that a hormone that controls fluid loss would have any earthly connection to settling down, but you’d be wrong. Vasopressin (often referred to as anti-diuretic hormone or ADH) controls how much water and sodium your kidneys get rid of at any given time. Its role in this part of the body is well understood, but it’s apparent that when you take it away, your sense of devotion can also diminish: a case of love truly going down the toilet.