If opposites attract, why do men and women seem alike when they fall in love?
Women and men may sometimes seem to be from different planets, but when they fall in love, their neurochemical orbits grow closer. That’s the conclusion of Donatella Marazziti, Ph.D., a professor of psychiatry at the University of Pisa (Italy) who found that during the first few months of a relationship, a woman’s levels of testosterone (a sex hormone tied to aggression) rise, while a man’s fall off.
Those changes, Marazziti says, may create a kind of hormonal common ground. “Women and men are very different,” she observes. “In order to mate, nature needs to eliminate some of those differences.”
This isn’t the first evidence that romance alters a person’s biochemistry. A few years ago, a team led by Marazziti found that people in love have lower levels of the neurotransmitter serotonin—a deficiency shared by patients with obsessive-compulsive disorder, and one the researcher attributes to the similarly obsessive nature of early infatuation.
The scientists also uncovered chemical evidence that new love is less than carefree: Men and women who were dating had much higher levels of the stress hormone cortisol.
The changes Marazziti has observed are usually temporary—love, alas, is ever-fleeting, and serotonin and testosterone levels generally return to normal within a year or two.
She now plans to conduct a long-term study of attachment in which she will measure levels of a hormone called oxytocin. This substance, which is released during breast-feeding, is essential to mother-child bonding. Oxytocin is also produced during orgasm, however, and Marazziti hopes to find out if it functions as the biochemical “glue” in long-standing adult relationships.
“For a long time, emotions have been neglected by experimental science,” Marazziti says. “But they’re important. It’s time we started examining them.”