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All you need is love

Cupid, the son of Venus, was the Roman god of love. He took the form of a winged child carrying a bow and a sheaf of arrows. The wounds Cupid inflicted caused his victims to fall in love.

Despite mythology, when it comes to love we are actually at the mercy of our biochemistry. Anthropologist Helen Fisher proposed that we “fall in love” in three stages and each involves a different set of chemicals.

Phase 1: Lust
Lust is driven by the sex hormones testosterone and estrogen. Testosterone plays a major role in the sex drive (also known as libido) of females as well as males. “Falling in love” decreases a male's testosterone levels, while increasing a female's testosterone levels. Estrogen is secreted by a female’s ovaries and placenta. It stimulates changes in the female reproductive organs and promotes development of female secondary sexual characteristics.

Other chemicals are active during the lust phase. Pheromones, odourless chemicals detected by your nose, help guide you to select an appropriate mate. Perhaps this ensures that you don't choose someone you’re closely related to. Phenylethylamine, the feel-good substance found in chocolate, keeps you coming back for more.

Phase 2: Attraction
When people fall in love, they can think of nothing else. Some people lose their appetite and need less sleep. Psychologists state that this phase closely mimics the symptoms of mental illness.

Neurotransmitters are the chemicals that a nerve cell uses to communicate with another nerve cell or with a muscle. In the attraction phase, a group of neurotransmitters called monoamines play an important role. Monoamines are thought to trigger emotion, arousal and cognition. Interestingly, medicinal drugs which increase the effect of monoamines may be used to treat patients with psychiatric disorders, including depression, anxiety and schizophrenia.

A few key monoamines in the attraction phase are:

  • Dopamine—affects brain processes that control movement, emotional response and the ability to experience pleasure and pain.
  • Norepinephrine—otherwise known as noradrenaline. This starts us sweating and gets the heart racing.
  • Serotonin—the serotonin effects of being infatuated have a similar chemical appearance to obsessive-compulsive disorder; which could explain why people experiencing infatuation cannot think of anyone else.

Phase 3: Attachment
In this phase a couple’s bond solidifies. Scientists believe that there are two major hormones involved here: oxytocin and vasopressin.

  • Oxytocin—released by both sexes during orgasm. It is thought that oxytocin promotes bonding when adults are intimate. The theory goes that the more sex a couple has, the deeper their bond becomes.
  • Vasopressin—scientists discovered that vasopressin may play a role in long-term relationships. They discovered this while studying the prairie vole, a small North American rodent. In prairie vole society, sex is the prelude to a long-term pair bonding of a male and female. The research showed that when the male prairie vole had his vasopressin suppressed, the bond with his partner deteriorated immediately.

If you are now prepared to fall in love, on your next visit to TELUS World of Science, check out the Love: It’s Chemistry exhibit in The Science of Sexuality.

The Science of Sexuality responds to the main concerns of the young and not-so-young alike. It broaches sexuality in a positive, frank and respectful manner. This innovative exhibition was developed with the help of sexologists, doctors, scientists, teaching specialists, parents and youth.

For more information:

Royal Society of Chemistry | Cupid's Chemistry
TIME Magazine | Helen Fisher | Biology: Your Brain in Love
Helen Fisher, PhD
National Geographic | True Love 
BBC Science | Sensual Signals: Sniffing out a Mr or Mrs Right
BBC Science | Does love drive you mad? 
Nature | A role for central vasopressin in pair bonding in monogamous prairie voles | Nature 365, 545 - 548 (07 October 1993); doi:10.1038/365545a0
Your amazing brain | The science of love