Love is a many-splendored thing. There are many splendid hormones and chemicals that flood your brain and induce that curious, almost drug like state, of “going gaga”.

Indeed, a bunch of intriguing human and animal experiments have unraveled the key processes involved in love. And they tell us that there is no magic to the sickening feeling – it’s just chemistry. The studies also open up a tantalizing proposition: that we could mimic the chemical cocktails of love in a pill, so creating the ultimate “love drug”.

Love 101

Love is, of course, an incredibly complicated feeling. Unlike the visual cortex, which sits at the back of your brain and processes the information you see, there isn’t a “love cortex”. But, experiments have found that when people in romantic love are placed into a brain scanner particular areas of their brain do light up.

This increased activity in particular areas of your brain, is caused by a release of “love” chemicals and hormones. Back in 1999, Donatella Marazziti of the University of Pisa in Italy found that levels of the brain chemical, serotonin, drop below normal in people claiming to be in love. Serotonin has a calming effect, so seeing levels fall could explain why we get a little overexcited when we start falling love.

Intriguingly, people with obsessive compulsive disorder suffer the same chemical imbalance, and perhaps that’s not too surprising. After all, both groups spend large amounts of time pining and obsessing over something or someone.

More recently, Marazziti found that the sex hormone, testosterone, also gets mucked around during love. Testosterone is linked to sexual desire, and aggression. Generally, when people are given the hormone they report thinking more about sex, having more sex and being more satisfied after sex.

Curiously, men who recently fell in love had lower levels of the stuff than other fellas. But, women stung by the love bug had higher levels of testosterone compared to their emotionally stable compatriots. It’s not completely understood why this happens – but could explain why some women get more randy in the first stages of love, while some men are keen to cuddle.

Other things happen as we fall in love. Particular areas of the brain – so called “reward centres” – become inundated with the chemical dopamine. This also happens when we eat chocolate, take addictive drugs, and have sex. The boost is thought to birth an intoxicating link between feeling damn good and the object of our affection. So, when we feel good – we start of think of our lovers. Just like a drug, we soon start to crave them, and want another hit. Indeed, Larry Young, a neuroscientist at Emory University in Atlanta and his colleague Miranda Lim, described the brain activity of people looking at their “schnookums” as being “remarkably similar to those observed after cocaine”. (pdf)

Long term love

Overtime, something curious happens. The initial excitement of the relationship drops away and a stable, satisfying, but somewhat irksome situation emerges – a long term relationship. This begins what scientists call, “pair bonding”. And now, a new suite of hormones kick in.

Meet oxytocin, also cringingly dubbed the “cuddle chemical”. Oxytocin is believed to have an important role in stimulating love-dovey behaviour in gals. Its close cousin, vasopressin, has been implicated in getting males to do funny things to express their love – like getting aggressive toward potential rivals.
While these chemicals were also getting pumped out when you started your relationship, their main role seems to be for creating long-term partnerships. Like dopamine, oxytocin and vasopressin also move through the reward system of the brain, hitchhiking off the same circuitry used by drugs, chocolate, and sex to give us a high.

Voling around

Oxytocin’s role in bonding is thought to be incredibly powerful. We think this thanks to a bunch of guinea pig-like rodents called voles. North American prairie voles (Microtus ochrogaster) are pillars for a modern family. They form lifelong partnerships, the males help raise the kids, and females help build the nest. Plus, the couple have more sex than they need to make babies – which is pretty rare in the animal kingdom. Not only do these cute little animals create great animal models for what is involved in long term partnerships, but they also have interesting cousins: montane voles (Microtus montanus). The two species are similar in every aspect of their lives, except one, montane voles like to slut around. They are polygamous. Turns out the chaste and floozy voles respond to oxytocin and vasopressin very differently.

As soon as scientists infuse the brain of the demure female prairie vole with oxytocin, she quickly becomes attached to the nearest male around. Similarly, getting vasopressin into the monogamous males also encourages so-called “pair-bonding activity” like spending time together – just the two of them – and driving away sexual competitors. But, if scientists boost the levels of these hormones in the philandering montane voles it doesn’t really affect their behaviour. Why are the species so different?

Oxytocin and vassopressin change our feelings by docking onto specially designed receptors found in particular sites around the brain. The voles’ brains have receptors for these chemicals in different places around their noggin. For example, monogamous voles have more receptors for vasopressin in front parts of their brain, compared to the strumpets.

Remarkably, when researchers tweaked the genetics of the montane voles so their brain receptors looked more like the chaste prairie rodents, the modified voles became monogamous. That is, when the males had the chance to go with three gals, they preferred to “huddle” with just the one.

There is human version of this gene, and there are slight modifications of it in different men. Blokes with a particular version of the gene are more likely to be unmarried than men without it. And if men already tied the knot, those with the “Mr Wrong” genes are twice as likely to report a recent crisis in their marriage.

Motherly Love

But is it so bad to be unmarried, or polygamous? And, why do we feel “love” at all?

Looking to the animal kingdom, long term partnerships are rather rare. It’s believed that less than 5 percent of mammals are monogamous – so obviously you don’t need to survive in the wild with a partner in tow. Evolutionary biologists believe that love wasn’t meant to exist in its popularised Shakespearean form. Rather, the brain mechanisms that allow us to feel the euphoria of love were supposed to be for mothers to bond with their infants, but later hijacked and used for lovers.

Without getting Freudian, this does explain some very curious phenomena: such as why the female breast is considered erotic for males, and why stimulating the cervix and nipples can feel quite nice. There are a few bits of evidence to suggest why this might be the case. Unlike the rare partnerships that humans form, motherly love is seen in a fair few animals – including a ewe and her lamb, and a female macaque and her offspring.

Plus, the same chemical cocktails that create romantic love also drive the love of a mother and her kin throughout the animal kingdom. For example, humans, rats and sheep release oxytocin during labour, delivery and nursing.

Love Drug

Once love stops becoming ethereal, but instead is whittled down into a chemical formulation brought to you by evolution – it opens up some exciting, and rather frightening, possibilities. Could scientists actually create a “love potion”? A squirt of oxytocin, a dollop of dopamine, and a smattering of testosterone sounds like a good start.

Indeed a squirt of oxytocin into the nose has been shown to enhance trust and make people more generous and empathetic. Already, you can go online and buy oxytocin perfume spray. But, when it comes to love, nothing is simple.

Studies have found that while the “cuddle chemical” encourages trust and cooperation amongst compatriots, it make people more suspicious of those from different nationalities. Inhaling oxytocin can also make people more envious, and gloat more vigorously over the misfortune of others.

There are some practical problems with a love perfume. Adam Guastella, a clinical psychologist at the University of Sydney who studies the effect of oxytocin nasal sprays, points out that it is a very fragile chemical. It will break down incredibly quickly if sprayed like cologne on clothes, and is unlikely to do anything for your relationships – except possibly boost confidence. For any effect, oxytocin needs to be rammed right up your nose.

In the future, however, a sophisticated love drug could be invented. There are some rather creepy uses for such an invention, which were carefully canvassed in Harry Potter. But, such a pill also could open up lines of communication in troubled, but once, loving relationships.

In fact, Julian Savulescu and Anders Sandberg both at the University of Oxford make a rather convincing argument that modern marriages are in great need for such a concoction (pdf).

Stable and loving relationships are known to improve the mental and physical health of the couple and any children produced. But sticking out an unloving partnership, does little for anyone’s health.

Savulescu and Sandberg note that throughout most of human history people survived for around 35 years, and assuming half of the couples got together when they were 20, many “mating alliances” would have ended within 15 years. “This figure is surprisingly close to the current global median duration of marriage, 11 years,” they wrote in an article written for New Scientist Magazine earlier this year. According to the team, given that our modern life spans are much longer, a chemical antidote to fill the gap with chemicals might be very useful.

No one is suggesting that chemicals will be the panacea for long-lasting and happy relationships, but slipping a “love pill” into a spouse’s drink every now and then after twenty years of marriage doesn’t sound so bad.

All this talk of hormones and chemicals, shouldn’t wipe out the romance of love. Perhaps, understanding what’s happening to your brain as you fall hard will help you find your perfect match. Maybe, you’ll be less likely to become victims to oxytocin, and douchebags, if armed with an explanation for your feelings.

But, maybe we just can’t control who we fall in love with – even if we can name the chemicals that are responsible for it.