Oxytocin May Keep You from Cheating

It's basically the opposite of Love Potion #9. Rather than transform a guy who can't find romance into a full-blown Lothario who falls in love with anything that moves, oxytocin might actually curb a committed man's desire to pursue anything but a monogamous relationship. It's like nature's little bottle of marriage counselor juice trapped inside our brains.

Scientists at universities around the world who study the "love hormone," as it's known, have been on a tear this year. It's looking more and more like the biological adhesive that is well-known for facilitating mother-child bonding might also plays a major role in sex, orgasm, and pair bonding. (It's also got some interesting implications for our addiction to social media.) Put differently, the process of bonding with a newborn might be similar to the process of bonding with a new beau.

A study from the Bar-Ilan University of Israel released early this year found a positive correlation between oxytocin and the success of new couples. Researchers measured the oxytocin levels of 120 20-something-year-old people in new relationships, then checked back in with those couples six months later. The ones who had stayed together registered higher levels of oxytocin in their blood — like, twice as high. Researchers also noted that couples high on oxytocin were more touchy-feely and prone to eye-banging one another during interviews for the experiment. The study concluded that doses of oxytocin "may improve specific relational components among couples in distress."

"These findings suggest that [oxytocin] in the first months of romantic love may serve as an index of relationship duration," the researchers wrote. However, because researchers only got to people after they'd already paired up, it's unclear whether having high oxytocin drives a person into a relationship or the relationship drives the hormone levels.

Yesterday, a group of German scientists published a study that picks up where the Israelis left off. Not only do they confirm that oxytocin helps two loving people bond, it actually keeps men from straying, the study says.

Researchers at the University of Bonn took 57 straight guys — half of whom were in monogamous relationships — and dosed them with either a nasal spray shot of love hormone or a placebo, then stuck them in a room with a foxy lady and watched what happened. This is where it gets tricky. During these little trysts, the woman moved in close and also pulled further away, and the guys were later asked what distance was "ideal" and how close or far made them feel "slightly uncomfortable."

The attached men who had been given oxytocin kept a "much greater distance" of about 10 cm to 15 cm from the woman than single guys did. They didn't, however, keep that same distance when approached by other guys.

The "results suggest that where [oxytocin] release is stimulated during a monogamous relationship, it may additionally promote its maintenance by making men avoid signaling romantic interest to other women through close-approach behavior during social encounters," the researchers wrote. "In this way, [oxytocin] may help to promote fidelity within monogamous human relationships."

Of course, the question of whether a man staying about a foot away from an attractive woman is enough to confirm his undying commitment to his girlfriend is still up in the air.