The science of falling in love

If you have had the happiness (or misfortune for some) of falling in love, you will know very well that it is a very difficult experience to explain; sometimes your mind and body act in ways you don't plan and you feel a mix of emotions that keeps you awake. Although all of this is triggered by psychological factors, there is a biological and chemical explanation that describes much more precisely what happens behind the phenomenon.

The process of falling in love is commonly divided into three stages, because in each of them the body experiences different phenomena. But something they have in common is that they all take place in the brain, since love could be defined as a neurological process in which parts such as the hypothalamus, the amygdala, the prefrontal cortex, the nucleus accumbens and the ventral tegmental area collaborate. So saying that you love someone with your heart turns out to be illogical.

The stages of love in the brain

The first of these stages is desire, which begins practically when we begin to feel an attraction for someone, when we get a new 'crush', for example. The brain immediately perceives what is happening and starts secreting pheromones and sex steroid hormones, namely testosterone and estrogens, in both men and women.

When we begin to have the suspicion or even the certainty that this special person might return our love, the second stage is triggered, which is known as attraction. This stage causes the release of chemical compounds called monoamines, among which are dopamine, serotonin, phenylethylamine and norepinephrine.

Not all lovers get to experience the third and final stage, called affection or attachment, since it is usually reached only some time after a stable relationship has begun. From this stage on, oxytocin, vasopressin and endorphin take over.

Now you are probably wondering: what are all those chemical compounds, and what do they do?

Love is symptomatic

I think that it has happened to almost all of us that when we finally work up the courage to talk to our crush or even send them a message, we get nervous, we overthink the words we will say, and our hands can even get sweaty and our voice shake. This is completely normal, because when we are in the first stage of love, the body tends to treat what is happening as a stressful situation.

Something related to the effects of the second stage is the phrase "love is like a drug", and it is actually not that far from reality, because both drugs and falling in love produce high levels of dopamine, which generates a constant euphoria, desire, dependence and withdrawal in both scenarios; and because of that, after a while of interacting with that special person, we realize that we are excited to see them, that our heart rate accelerates when we are with them and that, without meaning to, we cannot concentrate because we always have them in our thoughts. To this are added the effects of serotonin, which affects our mood making us feel happy when we are with that person or sad when we are not; and also those of norepinephrine, which in addition to causing insomnia and loss of appetite, increases our ability to remember new stimuli, making us remember the smallest details of every encounter with that person.

In the stage of affection, the effects of vasopressin and oxytocin cause the intense, excessive love we felt in the second stage to fade, making room for a feeling of attachment. Vasopressin helps the attachment last, and oxytocin, nicknamed the 'hug hormone', builds a closer emotional bond through physical contact. Likewise, a feeling of calm and stability is generated with the other person thanks to endorphins, since extra doses of these substances reduce pain, so that even the most insignificant things bring us joy.

One of the most representative symptoms of love is the so-called 'butterflies in the stomach', a tingling in the abdomen that is set off when we see our loved one. It usually appears in the second stage of love, though not strictly, and unlike all the symptoms mentioned so far, it is not caused only by the release of a chemical substance.

What really are butterflies in the stomach?

It all starts in the autonomic nervous system (ANS), which is divided into the parasympathetic ANS and the sympathetic ANS; the first is the one that slows our heart rate and makes us feel relaxed, and the second is the one that activates in just a few milliseconds to secrete adrenaline and cortisol when the body feels in danger. The change from one ANS to another is the exact reason for this turmoil that we feel in the stomach; this state of nervousness, uncertainty and worry, perhaps caused by a first date, is interpreted by the body as a situation that puts us at risk. And when the body switches to the sympathetic ANS, some of the blood that was in our digestive system is diverted to the muscles of the arms and legs, since they are ideal for escaping a situation of real danger; our stomach realizes the lack of blood and oxygen, and sends a signal, in protest, that we feel as a flutter of butterflies.

Without a doubt, falling in love involves many temporary changes in our body, which biology and chemistry are able to explain; however, there are no strict rules for falling in love, since questions such as why we fall in love and how deeply we can fall for someone are things that science cannot yet cover, because the emotional side of love is still very abstract.