Rene Hurlemann, MD, PHD, of the university of Bonn is leading a study into the effects of the hormone Oxytocin on heterosexual males in committed relationships. They placed the hormone into the system of a male in a committed relationship (Called M-r) through a nasal spray and 45 minutes later they introduced an unknown attractive female (U-f). The female would move closer to M-r but M-r had to say when the distance between them was uncomfortable. They conducted this test with Oxytocin introduced in heterosexual single males (M-s) and they also, for comparison, introduced a placebo into M-s and M-r.
They found that with an increase in Oxytocin levels the minimum distance between M-r and U-f was greater than with M-s with Oxy, M-s no Oxy, M-r no Oxy. With repeated results and minimization of errors, they had shown a relationship between the hormone and infidelity.
Oxytocin is produced in the hypothalamus (Figure 1) and it is produced by magnocellular neurosecretory cells which are large cells in the supraoptic nucleus (abbreviated - SON shown in Figure 2) within the hypothalamus. SON contains around 3,000 neurons.
Figure 1 - Overall cross section of head and magnification of Hypothalamus (Green)
Figure 2- Map showing SON which is shaded.
The hormone plays roles within females such as Lactation (Let down effect) and Uterine contraction. Also:
"Previous animal research in prairie voles identified oxytocin as major key for monogamous fidelity in animals," Hurlemann said. "Here, we provide the first evidence that oxytocin may have a similar role for humans."So the hormone has an effect on fidelity (even in mammals that are not human or prime-ape) and some motherly processes in female humans. This research is now showing it has effects on males in committed relationships. Hurlemann's team also conducted an experiment between M-r with Oxy and U-m (unknown males) and this did not follow the same pattern, nothing interesting happened. What Hurlemann's team could do for future research is conduct the same experiment on homo sexual men in committed relationships and vice versa and see if this has the same effect.
Read more at: http://medicalxpress.com/news/2012-11-hormone-affects-distance-men-unknown.html#jCp
Obviously do not try and introduce this hormone into your boyfriends system without his consent, but maybe in marriage counselling where promiscuity is a problem... they may recommend a nasal spray of oxytocin before a night out so the man is less likely to cheat. (Assuming no knowledge of trust between partners).
Stay tuned for more science news!