Head or heart? The science of love, lust and attraction

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Love: a squishy feeling radiating from the heart, or an evolutionarily programmed balance of neurotransmitters in the brain? The cold hard evidence of science feels distant from such a personal, intimate experience. Yet, as medical technology has advanced over the last 20 years, the number of scientific research articles trying to dissect the neurobiology of love has rocketed. So, if there really is a chemical formula for love…what is it? And why do we crave it?

The Evolution of Love

Feelings of lust are driven by the need for sexual gratification and an evolutionary drive to propagate one’s genes into future generations. However, ‘romantic love’ is distinct from lust. It refers to an intense infatuation with a potential partner and a strong desire for union with them. From an evolutionary perspective, many characteristic courtship behaviours in animals that aim to attract a mate are also seen in human romantic love. For example, both courtship behaviour and romantic love are associated with obsessively wanting to spend time with a partner; intensely focusing on winning a partner over; and affiliative gestures or behaviours. While red-capped manakins choose to perform an impressive birdsong and peafowl peacocks flare an elaborate display of feathers, perhaps a particularly enthusiastic dance in Babylon on a Wednesday night is an evolutionary-driven courtship behaviour? Who knows?

Love is Like a Drug

Oxytocin and vasopressin are heavily involved in the neurobiology of love. These neurohormones bring about action by binding to neuron receptors in the brain and across various tissues in the body. Studies have shown that couples in the initial stages of their relationship have significantly higher levels of oxytocin and vasopressin compared to people not in a romantic relationship. Specifically, oxytocin and vasopressin are released upon orgasm or ejaculation, and during skin-to-skin contact. While the release of oxytocin has been associated with feelings of safety and relaxation, the release of vasopressin is linked to the evolutionary urge to protect and guard a partner.

Dopaminergic neural networks are heavily involved in the ‘reward system’ of the brain. Dopamineinnervated regions of the brain tend to have a relatively high density of vasopressin and oxytocin receptors. This means that the enhanced release of vasopressin and oxytocin after sex is associated with a pleasurable feeling of reward. This enjoyable ‘dopamine high’ could explain why many people crave the so-called ‘honeymoon phase’ of meeting a new romantic partner. In fact, neuroimaging studies have shown that there is a remarkable similarity in the reward and emotional regulation neural networks of people experiencing romantic love and people with drug addiction. Love really is like a drug.

There is similarity between the brain patterns of people experiencing romantic love and people with drug addiction

Thinking About You…

Ever heard someone say they can’t eat or sleep because they’re ‘too busy’ dreaming of a new lover? Well, there might be a scientific reason for it. Norepinephrine, a neurotransmitter derived from dopamine, is associated with increased alertness, loss of appetite and insomnia. Studies have shown that people in new romantic relationships have higher levels of norepinephrine than people not in a relationship.

If constantly thinking about a love interest isn’t enough, research suggests that regions of the brain associated with the dopamine reward system show significantly higher levels of activation when simply looking at a photograph of their romantic partner compared to a photograph of a familiar acquaintance. These feelings of pleasure and desire make us crave spending time with a romantic partner. So, next time you are desperately racking your brain for a smooth compliment or pickup line, how about you go for ‘You know every time I see you…you really get my anterior cingulate cortex and posterior cingulate cortex activated…’.

In summary, love is complicated. This evolutionarily driven phenomenon involves a complex cocktail of neurotransmitters and hormones that make us head over heels for a new love interest. So, next time you find yourself daydreaming of a troublesome situationship… blame it all on the science.

Image: Tallie Robinson via Unsplash

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