Say you're a man in a committed, loving relationship and you spot a saucy minx making eyes at you. Turns out, you may not be terribly susceptible to her batting lashes if she's at apex of her fertility cycle – or so says science.
The issue of monogamy in homo sapiens has been questioned when one observes behaviors in the animal kingdom. With exceptions, it is the male that is wandering off, spreading his seed and propagating his progeny. From an evolution standpoint, it may behoove the male not to place all his proverbial eggs in one basket. New research from the Department of Psychology at the University of Haifa in Israel, dispels this view.
In a study, published in Scientific Reports, researchers conducted experiments, based on previous research demonstrating that men in relationships react with avoidant behavior towards attractive women and single men exhibit increased attraction toward women who are in peri-ovulation (most fertile). To further analyze how single versus "pair-bonded" men would behave toward ovulating females, the investigators conducted two separate experiments. The first observed how much distance subjects (n=75) would maintain or the Comfortable Interpersonal Distance (CID) from male or female figures after having been exposed to odor samples from women who were ovulating and those who were not (luteal phase). The second experiment tested how subjects (n=43) would rate the sexual attractiveness of women and beauty, separately, after having been exposed to the odors of ovulating and non-ovulating females.
In the first experiment, they found that pair-bonded men maintained statistically significant greater distances from both males and females if they were exposed to odors from ovulating women. In the second experiment, single men did not rate attractiveness with any degree of significance after having been exposed to the odor of highly fertile females. However, committed men did rate women as less sexually attractive if they had been exposed to the odor of an ovulating female without any marked difference in their assessment of beauty.
The authors speculate that the differences observed in pair-bonded men could be explained by their motivation to maintain their current relationship and that which threatens it should be avoided. One measurable method of assessing this reaction is by following testosterone levels. Heightened sexual desire and mating stimulates testosterone surges in males. The paper notes that basal testosterone levels are higher in single males than in their pair-bonded counterparts. The authors offer that males who are in relationships are able to squelch the behaviors associated with surges in testosterone thus making them less vulnerable to alternative partners. Single men, they say, have lower arousal thresholds when they experience testosterone surges.
One potential problem in this study is responder bias. The men in the study who were in committed relationships behaved in a more reserved manner so as to not be poorly perceived. The sample sizes calculated are at the bare minimum of observing any real effect.
From a female perspective, it serves as some comfort that men in relationships are not slaves to their surging testosterone levels or to the degree of fertility of some doe-eyed damsel they should happen upon. Behavior and choices are governed by a slew of factors interwoven in a complex fabric – hormones are but a mere thread.