Written by David del Rosario on Monday January 9th, 2017

David del Rosario

Written by David del Rosario

1 year ago

I was spending a few days at my parents’ house and the television was, as usual, switched on. Inside the idiot box a group of people were shouting (something unusual and inexplicable on television) so I looked around and, as nobody was there, I grabbed the remote, determined to put an end to that nonsense. Then something happened that made my hairs not only stand on end but shoot out of my capillaries, go for a walk around my body, giving me the shivers, and then come back without batting an eyelid to form rows. A spine – chilling experiment that was attempting to freeze the exact moment two people fall in love, was being broadcast live on television under a codename: Women and men and vice versa. That smelled like quite a feat.

This is how I decided that this article would talk about science and romantic love, while trying to answer the four questions my nephew would ask. Sometimes there is no choice but to go into marshy terrain, cross the battlefield, be on the limits of an offside trap, or have sex in your parents-in-laws´ house, for which you need tons of courage (not Dutch, my drinking friends).


The chemistry of “Women and men and vice versa”

Although I would swear that my high school literature teacher would write, ” Women, men and vice versa ” (a subject that we will leave aside), this “Telecinco” program offered a mess of the same caliber we find in scientific experiments. Participants in the “study” (2 men and 2 women between 19 and 30 years of age) receive suitors who come in search of love. The set becomes a laboratory where the encounters take place from Monday to Friday for 75 minutes, and the rest of the time they get on with their lives without having any contact outside the laboratory. Anyone who did not follow these conditions to the letter would be expelled from the experiment (and the program). Continuing with the analogy, those people who see Cupid´s arrows pass them by and do not find romantic love would become the subjects of control.

Looking for precedents in scientific literature I found two researchers from the University of Pisa in Rome who carried out their particular “Women, men and vice versa”, over a period of 6 months, studying 48 couples who have found love. An organism in love changes its biochemistry with the help of four hormones (messenger pigeons) that induce changes at the physiological level: serotonin, dopamine, cortisol and testosterone.

Serotonin, the hormone of happiness, is related to calm and well-being which makes love sometimes equate to a “drug”. At the same time, dopamine controls the center of pleasure and regulates our behavior, motivation and, therefore, the desire to repeat a behavior (it is serotonin´s first cousin). On the other hand, cortisol is responsible for regulating stress, while testosterone manages physical and mental energy, generosity, or promotes the protection of future children and sexuality. Adding on the effects of each hormone would build up the feeling of falling in love.


The brain in love

You may have noticed the stupid things we humans do or how complicated it is to make someone “see sense” when he/she is in love. Well, this behavior has a neurological basis. The headline would be: “A brain in love disconnects the prefrontal cortex.” This area (which you would cover with the palm of your hand if you put it on your forehead) is normally associated with reasoning and allows us to anticipate things. A prefrontal cortex in love becomes a neet, a lost teenager who does not fear the consequences and shows an Obsessive Compulsive Disorder towards his beloved. So mothers, fathers, or friends from all over the world, do not try to make prefrontal cortex in love see reason, because you are wasting your time; his/her brain has disconnected the reasoning process. It is much easier to bite your elbow than to reason with a brain in love.


4 Difficult questions about romantic love

After you have probably tried to bite your elbow, I would like to emphasize that up to now we have been dealing with “easy” issues (those that science formulates and we can measure in an experiment with a reagent, or using a neuroimaging device). Now it it´s time for tough questions: the ones my eleven-year-old nephew would make about romantic love.

To be really prepared to answer tough questions, we just need to know that romantic love has 3 differentiated stages in each of which both the hormones involved and the brain activity are different. The formula of romantic love would be something like this:



4. Difficult questions about romantic love

The main function of falling in love is to procreate and learn. This first stage of romantic love would be the one we would experience in our time on Women, Men and viceversa (I can´t bear to even think about it) where a series of biochemical changes led by serotonin, dopamine, cortisol and testosterone, and neurological ones (disconnection of prefrontal cortex) lead us to unbridled passion, to the pursuit of intimacy and commitment. Longitudinal studies (which monitor the participants for years) warn that the biochemical changes of infatuation disappear without a trace after between one and two years.


3. What happens when the infatuation is over?

Once the stage of infatuation has passed, the organism´s neurochemical configuration changes significantly. The stars of the film now become oxytocin and vasopressin, which reduce stress and provide the confidence needed to strengthen the relationship. We are in the stage of passionate love where the goal is stability, balance and security. From a neurological point of view we are gradually recovering the connection with our beloved prefrontal cortex and, with it, the reasoning process.

Let me make it clear that “falling out of love” does not imply any loss of sexual or romantic passion. The relationship settles down and learning is triggered; the limits of intimacy are crossed and the commitment is strengthened (this looks great on Sternberg’s model, sorry that the images are copyrighted). This is when we say “I have a relationship”. The average period of passionate love can extend up to four years.


2. Does passionate love have an expiry date?

Let’s recap. We fall in love (for one or two years), consolidate a relationship based on passion and commitment (up to four years), and then most people have the feeling that the relationship “cools off.” And why is this? Mainly because after four years of a relationship, any trace of chemical or neuronal romantic love disappears.

Studying divorce rates, several investigators have noticed that 50% of couples break up shortly after celebrating their fourth anniversary. With these numbers under its belt romantic love seems to have an expiry date. Scientists found a biological excuse, and the fact is that we need four years to make our babies self-sufficient.

The absence of some kind of love chemistry results in a decrease in passion and intimacy and the relationship hangs on the thread of commitment. The couple enters a critical period. In this third stage the relationship can become friendship (what is known as “empty love”) or possibly both remain “in love” like the first day (something that is not biochemically and neuronally possible. Let’s understand it as a manner of speaking). According to the American researcher Art Aron, 70% of relationships become friendship, while 12.5% of couples are still in love like the first day.


1. How to remain in love with your partner like the first day, after having celebrated your silver wedding?

Answering this question would mean having in our hands the Holy Grail of relationships, or the true love of Disney movies. When we scientists have studied couples, who, after celebrating their silver, gold or platinum weddings are just as much in love as the first day, we have met people who stand out for their generosity, very sociable men and women who tend to see the good side of things and enjoy sharing with others.



We humans are one of the few living beings that turn the house upside down looking for some glasses that we are actually wearing; we pay 6 months of gym membership all at once or wish each other a Happy New Year even into the month of February. On this path of neurolove I have asked many questions and found answers. Is it possible to have a long – distance relationship? Does a 10,000 km distance relationship affect the brain and hormones in the same way? Is love something truly universal? Why do men fall in love more easily than women? Or, how is it that watching romantic movies with your partner reduces the divorce rate?

I will soon share these ideas and other nonsense that goes through my head. Making the most of the date, I would like to wish all those who have made their eyesight worse from reading my articles (only to them): Happy New Year!



  • Zak, P.J., et al., Testosterone Administration Decreases Generosity in the Ultimatum Game. PLOS ONE, 2009. 4(12): p. e8330.
  • de Boer, A., E.M. van Buel, and G.J. ter Horst, Love is more tha hust a kiss: a neurobiological perspective on love and affection. Neuroscience, 2012. 201: p. 114–124.
  • Yela, C., Temporal course of the basic components of love throughout relarionships. Psychology in Spain, 1998. 2(1 ): p. 76-86.
  • Kalmijn, M., Explaining cross-national differences in marriage, cohabitation, and divorce in Europe, 1990–2000. Population Studies, 2007. 61(3): p. 243-263.
  • Fisher, H., Lust, attraction, and attachment in mammalian reproduction. Hum Nat 1998. 9: p. 23–52.
  • Rial, A., Repensar el cerebro. Sin fronteras. Cátedra de divulgación científica. 2016, Valencia: Universidad de Valencia. (Rethinking the brain. No limits. Chair of scientific dissemination. 2016, Valencia: University of Valencia).



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