Let’s Get Chemical: Oxytocin & Monogamy

by Haifa Haroon on February 16, 2013

As we wrap up the MTSG Valentines Day 2013 coverage, I want to expand on a topic touched upon earlier this week – monogamy. The blog post – which you should check out if you haven’t already – describes a theory on the evolution of monogamy. Whether or not this theory holds is a separate issue, but my question is: what determines whether two people will remain in a monogamous relationship? 

Courtesy of Paul Mannix via Flickr

According to a study published in the Journal of Neuroscience, it may have to do with oxytocin. Oxytocin is a hormone that is naturally present in our bodies. It plays an important role – it stimulates labor contractions as well as milk ejection when breastfeeding. Although this was familiar to me, I was surprised to learn that oxytocin is also referred to as the “love hormone”. This is because, in addition to being released during labor, the hormone is also released during sex, resulting in parent-infant and pair bonding, respectively.

Courtesy of The Journal of Neuroscience

The study consisted of positioning an attractive female (who was also a researcher) 24 inches away from a heterosexual male, who had been given either oxytocin (via nasal spray) or a placebo. As the female walked towards or away from the male, he was asked to say when he felt the gap between them was an “ideal distance” as opposed to one that made him feel slightly uncomfortable. The researchers found that men who were in committed relationships and had been given oxytocin were comfortable with a greater gap between themselves and the attractive female.

But, what if it was just a matter of not being attracted to her?

Although this is a possibility, the participants were later asked if they found the female attractive and their responses did not vary by relationship or treatment status (i.e.whether or not they received oxytocin). This suggests that although men that were in committed relationships found the woman attractive, it was the men who received oxytocin that were more likely to avoid “signaling romantic interest” when in close proximity to a female – leading researchers to conclude that the hormone may promote monogamy.

Given this finding, it may not be surprising that oxytocin levels are also associated with the longevity of a relationship. Researchers compared oxytocin levels among singles and new couples over a span of 6 months.  At baseline, new couples had oxytocin levels twice as high as singles and those that were still together at follow up, had stable hormone levels. However, couples that broke up over the 6 month period tended to have lower levels of oxytocin than they did at baseline.

This is a really interesting finding but investing in oxytocin nasal sprays may not be the best course of action.
Since oxytocin is a hormone, introducing it into your system when there isn’t actually a deficiency, may disrupt your natural hormone feedback cycle. Additionally, there’s researchthat shows that although oxytocin increases trust in other people – “trust hormone” – it tends to only increase trust among one’s group and lead to a “us” vs. “them” mentality.

Courtesy of Tampa Band Photos via Flickr

If you want to increase your oxytocin levels in other ways, here are some interesting ideas:

  • Hugs
  • Karaoke
  • Exercise
  • Dancing
  • Emotional films
  • Skin-to-skin contact
  • Checking Facebook
  • Using the L (OVE) word
Lola February 16, 2013 at 6:09 pm

Hi Haifa,
Interesting topic. I’m just curious what this research might suggest about oxytocin levels in longer term relationships (longer than six months), like say…oh ten years.???

Haifa Haroon February 18, 2013 at 12:26 pm

Hi Lola,

Unfortunately, I wasn’t able to find a study that measured oxytocin levels in people in longer term relationships. It would be interesting to monitor though!


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