Keep your distance: oxytocin is in the air.

Love is in the air…actually there is more cold and snow but don’t let that cool you down. Today we are talking about oxytocin. You know, that hormone they call the love hormone because it is secreted during coitus and it is partly responsible for those butterflies in your stomach at the beginning of a relationship. That hormone is also known for mediating prosocial behaviour, such as increasing trust and cooperation among individuals. But let’s not forget that as we mentioned in a previous post and like so many other things (specially in biology) their effects are context dependent, therefore oxytocin can also mediate aversion and lack of cooperation towards outsiders.

Until oxytocin splits them up…

Today we are dealing with oxytocin in the context she’s most famousfor: monogamy. However, this time we are not going to talk about prairie voles but humans. That is you and me, in case you had a doubt, and what happens when we are in a relationship. Specifically about what happens to the male part in heterosexual couples (unfortunately the study only involved straight men so for now we don’t know what happens to women or in gay couples). In an article published in The Journal of Neuroscience they propose oxitocyn as a mediator in monogamy in humans. How? By incrementing social distance from attractive women, be it alive or even in pictures. This effect would be restricted, however, only to those men in stable relationships, single men are not affected at all by oxytocin, at least in this sense. One thing is for sure not altered in any case: the perception of an attractive woman. It is not that oxytocin makes them blind to them it is just that it keeps them at bay.

Now, how did they test this hypothesis? They took a group of 86 straight men, part single part in relationships and they gave them randomly either a placebo or oxytocin inhaled. Right after they were placed in a room with an attractive woman and the distances between them measured. This measurements took place under different conditions such as that the woman would look at them (which is a sign of interest that usually produces a shortening of the distance between 2 people) or that she’d walk or stood still. The same experiment was performed with a male experiementer instead of a woman as a control. At one point they were also asked to rate the attractiveness of the woman in the experiment and how much sexual interest they had in her.

In another part of the experiment the subjects were shown a series of pictures of valence either positive (women, landscapes…) or negative (violence…) and their reactions (movements towards/outwards) quantified.

Guys with a girlfriend know how to keep their distance. Thanks to oxytocin?


What came out? It seems that guys with girlfriends under the oxytocin condition kept a bigger distance from the woman than singles, independently of the signs of interest displayed by the woman. They also observed this “good” guys also took longer in getting closer to pictures of nice looking women than singles. All these results independent of their assessment of the experimenter’s beauty, which was high, according to all. When the experimenter was a man both groups behaved similarly. It seems what’s important here is the girl.

The authors of the study comment about the results that they are yet another proof of oxytocin having variable effects depending mostly on context (in this case being single or in a -happy- relationship) and that this is the first time this effect has been observed in humans: that oxytocin also helps in maintaining the bond in a monogamous relationship altering male behaviour as it was shown previously with prairie voles.

Now comes what I think. All sounds good and fine BUT I am missing data. On the one hand I would have liked to see the levels of circulating oxytocin, specially in the “coupled” guys cause in their case, just for being in a relationship (and having, in theory frequent and regular sex) they should already be higher than in singles (as an average), therefore the effects could simply be dose dependent and not state/context dependent. On the other hand, being in a relationship doesn’t mean being in love. Would results have changed if this parameter would have been included? Would a man in love but not in a relationship keep also his distance? If there are psychological pregnancies why can’t a platonic lover respond/have oxytocin levels similar to someone in a relationship? I guess not, but I’d liked to see that simple control.

Meanwhile, I must confess I feel better knowing my man would know how to keep his distance thanks to this all-can-do hormone, but just in case tonight I am going to increase his circulating dose…