Olfactory hormonal signals for human behavior: can you smell ovulation and pregnancy?

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In this functional magnetic resonance imaging (fMRI) study, we will apply a translational research approach to investigate whether female chemical signals can mediate sexual availability and fertility in humans. In the animal kingdom, the successful detection of ovulation and pregnancy based on female body odor provides an evolutionary advantage in mate choice. In humans, it could be assumed that sexual selection is influenced in a similar way if men but also women could recognize from the body odor of the females whether they are ovulating or pregnant and could adapt their behavior accordingly. The proposed fMRI study will investigate whether the body odors of ovulating and pregnant women have a direct influence on heterosexual men and heterosexual (ovulating and menstruating) women. To this end, two fMRI experiments with visual stimuli will be conducted to investigate the basal effect of body odors on the evaluation of photographs of women's faces and to determine whether an increased level of arousal provoked by visual erotic stimuli is modulated by body odors and whether the evaluation of erotic photographs of women is altered. In addition, the underlying brain activity during exposure to body odors will be investigated while simultaneously assessing the photographs.In a pilot study conducted with heterosexual men, the results suggest that the detection of sexual availability activates the male brain regions associated with facial processing and rewarding/motivation, while the perception of pregnancy activates a region responsible for empathy and prosocial behavior. Thus, it can be concluded that this evolutionary mechanism of perceiving a woman's reproductive status through the body odor likely biases men toward paying more attention to ovulating women. In the proposed study, these results will be replicated and validated by including heterosexual women and the extended fMRI paradigm for sexual arousal.