For generations scientists have studied the peacock feathers of human mating, the swish and swagger that advertise sexual interest, the courtship dance at bars, the public display. They've left the private experience -- what's happening in the brain when we fall for someone -- mostly to poets.
We know there's an inborn human urge to mate, after all. Love is a mystery, a promise, an arrow from Cupid's bow.
Yet recent research suggests that romantic attraction is in fact a primitive, biologically based drive, like hunger or sex, some scientists argue. While lust makes our eye wander, they say, it's the drive for romance that allows us to focus on one particular person, though we often can't explain why. The biology of romance helps account for how we think about passionate love, and explain its insanity: why we might travel cross-country for a single kiss, and plunge into blackest despair if our beloved turns away.
This view of romantic attraction rests on observations of passionate behavior across cultures, studies of animals during courtship and, most recently, findings by scientists studying the human brain. Using magnetic resonance imaging, or MRI, machines to peer into the brains of college students in the throes of early love -- that crazed, can't-think-of-anything-but stage of romance -- scientists have developed some of the first direct evidence that the neural mechanisms of romantic attraction are distinct from those of sexual attraction and arousal.
"What we're seeing here is the biological drive to choose a mate, to focus on one person to the exclusion of all others," said Helen Fisher, an anthropologist at Rutgers University in New Jersey, who spells out the biological basis for romantic attachment in a paper appearing this month in the journal Neuroendocrinology Letters. "Let's say you walk into a party and there are several attractive women or men there. Your brain is registering this attraction for each one; then you talk to the third or fourth one, and whoosh -- you feel something extra."
Unique brain activity
Fisher's group is analyzing more than 3,000 brain scans of 18 recently smitten college students, taken while they looked at a picture of their beloved. She expects the results to build upon the findings of English researchers who recently completed a similar study of young men and women in love. When shown a picture of their romantic partner, their brain activity pattern was markedly different from when they looked at a picture of a close friend, reported neurobiologists Andreas Bartels and Semir Zeki of University College London. The pictures showed that the experience of romantic attraction activated those pockets of the brain with a high concentration of receptors for dopamine, the chemical messenger closely tied to states of euphoria, craving and addiction. Biologists have linked high levels of dopamine and a related agent, norepinephrine, to heightened attention and short-term memory, hyperactivity, sleeplessness and goal-oriented behavior. When they're first captivated, Fisher argues, couples often show the signs of surging dopamine: increased energy, less need for sleep or food, focused attention and exquisite delight in smallest details of this novel relationship.
Bartels and Zeki compared their MRI images to brain scans taken from people in different emotional states, including sexual arousal, feelings of happiness and cocaine-induced euphoria. The pattern for romantic love was unique. But there was some overlap with and close proximity to other positive states. "This makes sense," said Zeki. "These were young people who were practically willing to die for their lover. You would expect that the images would reflect many strong emotions all at once."
MRI machines can't read people's minds, psychiatrists say. The pictures are not nearly sensitive enough to separate and measure each of the emotions that comprise romantic feeling, as if they were on a color-by-numbers map. Yet the images' emotional complexity itself reflects how many people think about being in love, some psychologists say.
In one recent study, University of Minnesota researcher Ellen Berscheid asked a group of young men and women to make four lists: of all their friends; of the people they loved; of everyone they thought sexually attractive; and finally, of those with whom they were "in love." As expected, the last list was the shortest, usually just one name. That same person, however, appeared on all the lists. "It's this combination of friendship, affection and lust," Berscheid said, "that makes it so powerful."
