Chemistry, as we all know, plays a big part in love affairs. What we didn’t realise, however, is just how true that is.

By Brian Yap

For all the heart-centric imagery surrounding love, the part of the human body most responsible for romance is something that wouldn’t fit on a Valentine’s Day card – the brain.

Infatuation, for instance, is often depicted as someone following his or her heart. In reality, however, the heart has little to do with it. The feeling of attraction is actually the unromantic result of three neurotransmitters flooding the brain. There’s dopamine, which causes us to feel good. Too much of it, however, could lead to psychosis. This might help explain the behaviour of some lovebirds.

Then there’s phenylethylamine, which accelerates the flow of information between nerve cells, helping to increase dopamine levels. This neurotransmitter is also present in chocolate, red wine and beer. It’s unclear if this is also the scientific explanation behind beer goggles.

Finally, there’s norepinephrine, which stimulates the production of adrenaline, increasing heart rate. In other words, that feeling of your heart about to pop out of your chest when talking to that attractive new colleague isn’t caused by your nerves, but your brain.

With time, however, these three chemicals gradually stop flooding the brain. So if you’re wondering why your relationship doesn’t feel as exciting as it initially was, science has an answer too.

Something else should happen, however. Endorphins, which are sometimes called natural pain relievers, start taking the place of the three neurotransmitters. This change in chemical balance explains why excitement eventually gives way to a sense of calm, warmth and dependability.

Endorphins, which resemble opiates in their calming abilities, are also slightly addictive. It’s hard not to wonder if that’s the reason why the end of relationships are often so difficult and can lead to withdrawal symptoms. As with smoking, maybe going cold turkey is best. Too bad there’s no break-up patch or chewing gum you can buy from the pharmacy.

Does this mean love can be subject to the same scientific measurements as, say, the speed of light? Can the perennial question, how deep is your love, be answered with an exact figure?

Probably not. Even the best-known scientist in the world is dumbfounded when it came to explaining matters of the heart.

“How on earth are you ever going to explain in terms of chemistry and physics so important a biological phenomenon as first love?” Albert Einstein once asked.

The man widely considered a genius should know the unpredictability of love. After all, Einstein married his first cousin.