The Science Of Commitment

Up next in our science series: commitment. What makes us want to spend eternity with someone? Why do some people cheat? Why are others capable of resisting temptation? To answer these questions, scientists are researching everything from the biological factors that appear to impact the stability of a person's marriage to a partnered individual's psychological response to being flirted with by strangers.

Hasse Walum, a biologist working at the Karolinska Institute in Sweden, studied 552 sets of twins to determine the role biology plays in a person's ability to remain faithful to a partner. Walum tested the impact of a gene, often called the "fidelity gene," that regulates the brain chemical vasopressin, a bonding hormone. He found that men who carried a variation in the gene were less likely to be married than men who did not, and that men with the variation who did get married had an increased likelihood of martial problems. Approximately a third of men who carried two copies of the gene variant had experienced a significant crisis in their relationship in the past year, twice as many as the men who did not show signs of the genetic variant. Walum and his team are currently conducting similar research in an attempt to replicate their findings in women.

Other studies have found that some people are biologically programed not to cheat. An experiment at Florida State University tested men's interest in the 21 year old female subject at the center of the study. The researchers found that single men found her most attractive during the most fertile stage of her menstrual cycle, whereas men who were in relationships found her least attractive at the same time. The scientists believe that their findings can be explained by a subconscious part of the partnered men's brains that overrode their natural impulses to find the woman attractive, in favor of protecting the relationships - and the joy and security they offered - that they were already in.

"It seems the men were truly trying to ward off any temptation they felt toward the ovulating woman," Dr. Jon Maner, a psycholgist at Florida State, told The New York Times. "They were trying to convince themselves that she was undesirable. I suspect some men really came to believe what they said. Others might still have felt the undercurrent of their forbidden desire, but I bet just voicing their lack of attraction helped them suppress it."

Stay tuned for more on the genetic differences that influence faithfulness and impact your ability to resist temptation.

Related Story: The Science Of Commitment, Part II