Love

What is Love? Can chemistry help you find it? Probably not, but chemistry can help explain it.

Love is quite a complex subject - and not just for your single friend who got yet another cat. Love is something that has baffled philosophers and scientists for many years. For example, take the symbol for love: the heart. The heart was once believed to be the center for emotion and pleasure in the human body. However, it is the brain that controls love! Thanks to advancements in neuroscience and biochemistry, we now have a sound understanding of what love is and you’ve probably guessed what it is by now: it’s chemistry.

Love can be divided into three feelings: attraction, lust and attachment. Each feeling is accompanied by its own set of hormones, which are chemical signals that induce an emotional or physical response within the body. Hormones work by interacting with binding sites in the brain called receptors. Receptors and hormones bind specifically, kind of how a lock can only be opened by it’s associated key. When a hormone has the correct size, orientation and combination of functional groups, it forms temporary bonds with the receptor which unlocks a physiological response.

The feeling of attraction is controlled by the hormones Dopamine, Norepinephrine and Serotonin. Both Dopamine and Norepinephrine are part of the reward pathway in the brain and are released when you feel attracted to someone. Elevated levels of these hormones make you feel bubbly and excited. In contrast, during attraction there is a reduction in Serotonin. Higher levels of Serotonin are associated with feelings of happiness so it is counterintuitive that feelings of attraction decrease your Serotonin levels. A hypothesis for this observation comes from studying obsessive compulsive disorder (OCD). In cases of OCD, we see lower levels of Serotonin in the brain and this is associated with compulsive obsessive behaviour. This same kind of behaviour is observed when someone is infatuated, which most people experience in the initial stages of attraction.

The next feeling is lust, or the sexual desire for someone. These urges are controlled by the hormones Estrogen and Testosterone. Both hormones are found in men and women and when elevated, they result in an increase in libido. The final feeling associated with love is attachment; the feeling of closeness and friendship. This feeling is controlled primarily by the production of Oxytocin. Actions such as cuddling, hugging and kissing release Oxytocin. It is with the right balance of these 6 hormones (which dictate our feelings of attraction, lust and attachment) that cause us to fall in love.

So next time you want to say “I love you,” instead try “My Dopamine, Norepinephrine, Testosterone, Estrogen and Oxytocin levels are elevated for you.” On second thought, maybe don’t try that.