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Love Potion No. 5: Testosterone
Although it certainly isn't the most romantic hormone pumping through our veins, testosterone—the compound responsible for facial hair and fast driving—is necessary to warm up our internal love engines. And it isn't just for the guys, either. Testosterone also exists in the female body to stoke physical attraction and sexual arousal.
Love Potion No. 4: Serotonin
Serotonin is a somewhat counterintuitive hormone to make the list, since it actually promotes feelings of calm and contentedness. But it's possible to chart the lifespan of a romantic relationship by tracing the roller-coaster ride of serotonin in the brain. During the early attachment phase of love, serotonin takes a backseat, residing at low levels, while other reward-regulating chemicals take over.
As a result of that serotonin dampening, people become borderline obsessed with their beloved, unable to focus or eat whenever apart. Eventually, once a relationship solidifies, the raphe nucleus in the brain stem begins to cook up more serotonin, eliciting those warm and fuzzy feelings of togetherness that typify longer-term attachment. The only downside of that serotonin upshot is the loss of excitement, also colloquially known as the end of the "honeymoon phase."
Love Potion No. 3: Oxytocin
What happens in the brain during an orgasm? One word: oxytocin. Sexual intercourse promotes feelings of attachment over time in large part thanks to oxytocin, which is produced in the ventral tegmental area of the brain. This chemical could aptly be nicknamed the "glue chemical" since it does such a swell job of binding people together.
As its levels crest, oxytocin calms and combats the early-phase intensity of romantic attachment, easing us into more stable relationships. Research confirms that in women especially, oxytocin fosters trust, happiness, and bonding. This is the same nonapeptide compound that bathes a new mother's brain, establishing the maternal link between her and child, and that spikes when we look at a picture of a loved one.
Love Potion No. 2: Vasopressin
Prairie voles, as we've learned, are often regarded as the animal kingdom's mascots of monogamy. The bonding oxytocin and vasopressin are the key neurological ingredients to the voles' faithfulness. Pair-bond-promoting vasopressin saturates the nucleus accumbens, a brain structure pivotal in sensing satisfaction. In doing so, this chemical drives vole pairs to lifelong coupling. In one experiment at Emory University, scientists blocked vasopressin receptors in prairie vole brains, resulting in an outbreak of adultery. Conversely, cranking up the levels of vasopressin in the brains of meadow voles—some of the prairie voles' promiscuous cousins—sparked a monogamy movement.
Love Potion No. 1: Dopamine
Once testosterone gets the job done of attracting two people to each other and igniting their sexual energy, pleasure-inducing dopamine is released during sexual intercourse. By powering the brain's limbic reward system, this chemical cultivates the addictive satisfaction that comes with the euphoria derived from eating a delectable meal or making love or even using cocaine.
That neurological treat dopamine doles out in the early stages of romantic attraction is partially responsible for the thrill we get when seeing the object of our affection and the craving to be with him or her in between. Indeed, studies have demonstrated that the brain, thanks to dopamine and its neurochemical cohorts, processes and manifests love much like an addiction, compelling people to settle down and reproduce.
Though high levels of dopamine are characteristic of early-stage romance and obsession, its presence is also a hallmark of satisfying, lasting relationships years later. Functional MRI scans of couples married at least twenty-one years who reported being madly in love showed above-average activity in the brain's dopamine factory, the ventral tegmental area. So while oxytocin and vasopressin are important for establishing monogamy, dopamine ensures that Pablo Neruda's "endless simplicity of tenderness" remains long after the honeymoon phase fades.
The Real Science of Sex Appeal by HowStuffWorks.com (© Sourcebooks 2015)