New research has begun to illuminate where love lies in the brain and the particulars of its chemical components. Some of my favorite parts of this article:

“Marazziti compared the lovers’ serotonin levels with those of a group of people suffering from OCD and another group who were free from both passion and mental illness. Levels of serotonin in both the obsessives’ blood and the lovers’ blood were 40 percent lower than those in her normal subjects. Translation: Love and obsessive-compulsive disorder could have a similar chemical profile. Translation: Love and mental illness may be difficult to tell apart. Translation: Don’t be a fool. Stay away.”

“Biologically speaking, the reasons romantic love fades may be found in the way our brains respond to the surge and pulse of dopamine that accompanies passion and makes us fly. Cocaine users describe the phenomenon of tolerance: The brain adapts to the excessive input of the drug. Perhaps the neurons become desensitized and need more and more to produce the high—to put out pixie dust, metaphorically speaking.”

“Perhaps our choice of mates is a simple matter of following our noses. Claus Wedekind of the University of Lausanne in Switzerland did an interesting experiment with sweaty T-shirts. He asked 49 women to smell T-shirts previously worn by unidentified men with a variety of the genotypes that influence both body odor and immune systems. He then asked the women to rate which T-shirts smelled the best, which the worst. What Wedekind found was that women preferred the scent of a T-shirt worn by a man whose genotype was most different from hers, a genotype that, perhaps, is linked to an immune system that possesses something hers does not. In this way she increases the chance that her offspring will be robust.”