As the German band Mia put it, “My heart is dancing and every molecule is in motion”. In other words, there is not much behind the well-known feeling of butterflies in your stomach other than a lot of biochemistry.

What is love? The most wonderful feeling on earth, the certainty of having found the man or woman of your dreams, or simply the interplay of different hormones? If you are a proponent of evolutionary psychology, love serves little more than to ensure human survival. True romantics might not give heed to this explanation. However, if you look closer, it becomes apparent that a great deal of love is actually controlled by hormones.

In the carousel of hormones

Anna and Dominik are on cloud nine. They met six weeks ago and can hardly bear to spend a minute without each other. The carefree lovers have constant smiles on their faces and butterflies in their stomachs. “It was fate”, Anna describes her first encounter with her boyfriend. But was it really? If we look at the phenomenon of love pragmatically, there is little more behind its mechanisms than biochemistry; it is induced by the sex hormones testosterone in men and oestrogen and progesterone in women.

Understanding spring fever

Falling in love also seems to be subject to seasonal fluctuations. In spring, many people are particularly hungry for love. Love-struck couples can be found almost everywhere. There is also a reason for this: when nature reawakens, our melatonin levels drop. When less of this sleep hormone is present, we feel more active – in matters of the heart as well. At the same time, our serotonin (the happiness hormone) levels increase. If Cupid’s arrows do actually hit their target, it is impossible to say exactly how long the phase of infatuation will last – this depends on the individual.

Take a deep breath! Is the chemistry right?

But why is it this person in particular who makes our hearts beat faster? Infatuation starts in your nose and is transmitted straight into your brain. The question of who we fall in love with is linked to pheromones, which are olfactory messengers. They help us to determine whether our potential partner’s immune system is different from our own. The larger the difference, the greater the attraction. This benefits our future children. Different immunological constitutions give our offspring a better chance of survival because they have more varied genetic material. The pheromones are genetically determined endogenous scents that may be repulsive to one person and attractive to the other. There’s a reason some people pass your personal sniff test – and others do not. Ergo: the way to a person’s heart is not through the stomach but rather through the nose.

The biochemistry of love

Love may be a matter of the heart. However, a large part of love, lust, and infatuation takes place in your head. When we fall in love, a chain of biochemical reactions triggers a state of emergency that could rightly be described as a “love frenzy”. Dopamine, the “happiness hormone”, which is released by the hypothalamus and triggers euphoria in the reward centre of the brain, plays a decisive role in this. Other pleasure-promoting and stimulating substances (e.g. norepinephrine and phenylethylamine) are also increasingly released. They create a state of arousal in our bodies and sharpen our focus: our heart beats noticeably faster, our blood pressure and body temperature rise, and we concentrate entirely on one person.

Addicted to you…

By means of magnetic resonance tomography, scientists were able to demonstrate that this “biochemical love play” is visible in certain areas of the brain. When lovers looked at photos of their partners, the brain areas in which rational thinking takes place showed no activity. The reward centre, on the other hand, was activated. It is therefore not surprising that infatuation and addiction are closely linked in the brain.

While the body is flooded with dopamine during the infatuation phase, another hormone, serotonin, decreases until the levels resemble that of people afflicted with obsessive-compulsive disorders. Along with pheromones, this explains why lovers only have eyes for the object of their biochemical desires and why they tend to forget the world around them. Having butterflies in your stomach is without a doubt a unique feeling – and addictive.

Love serves the purposes of reproduction

As time goes by, biochemistry and the mind will rein in our feelings and bring us back down from cloud nine to cold reality – which is bad news at the time but good news in the long run. Because in the end, you cannot live on love alone. Our bodies are also unable to maintain the draining state of emergency in the long term. Why has nature designed things this way? The sexual and reproductive instinct is part of our animal heritage and simply serves to ensure reproduction and the preservation of our species.


As beautiful as love is, lovesickness can be painful to the very same degree. Julia’s world has been turned upside down. Only a few weeks ago, she was making plans for a future with her partner. Now it’s all over. Standing amidst the ruins of her relationship, she is completely and utterly miserable. The symptoms of her lovesickness are not confined to grief, anger, and despair. She can hardly sleep any more, she has lost her appetite, and she suffers from headaches. No wonder – after all, her body is under a great deal of stress. Heartache – withdrawal and decrease of the reward substances oxytocin and dopamine in the brain – is like a drug withdrawal, and there is a growing feeling of disappointment.

Mysterious love

There is no need, however, for romantics to despair in the face of sober facts. Even though science is coming ever closer to the “formula of love”, the mystery is far from solved. After all, it wouldn’t be possible to win over your dream partner with nothing but the hormones necessary for infatuation. Infatuation and love are complex processes. Romantics can therefore safely continue to float on cloud nine and accept love as it is: a wonderful feeling.

In the best case scenario, infatuation is followed by love. Here too, hormones – especially oxytocin – call the shots. Oxytocin is produced during breastfeeding and helps create the bond between the mother and child. Oxytocin also strengthens pair bonding and heightens our trust in others. This is an important step in keeping both parents together for the safety of the child.

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