Importance of Daily Sex Hormone Measurements Within the Menstrual Cycle for Fertility Estimates in Cyclical Shifts Studies

Recent discussions have highlighted the importance of fertility measurements for the study of peri-ovulatory shifts in women's mating psychology and mating-related behaviors. Participants in such studies typically attend at least two test sessions, one of which is, at least in theory, scheduled to occur during the high-fertility, peri-ovulatory phase of the menstrual cycle. A crucial part of this debate is whether luteinizing hormone (LH) tests alone are sufficient to accurately assign test sessions to the peri-ovulatory phase. This article adds to this ongoing debate by presenting analyses of a detailed database of daily estradiol levels and LH tests for 102 menstrual cycles. Based on more than 4,000 hormonal measurements, it is clear that individual differences in length of the cycle, length of the luteal phase and, perhaps most importantly, the discrepancy between the timing of the LH surge and the drop in estradiol that follows it are pronounced. Less than 40% of analyzed cycles followed the textbook pattern commonly assumed to occur in fertility-based research, in which the LH surge is assumed to occur not more than 48 hr before the estradiol drop. These results suggest that LH tests alone are not sufficient to assign test sessions to the peri-ovulatory phase and that analyses of sex hormones are essential to identify whether the participant was tested during the peri-ovulatory phase.

On the Communicative Function of Body Odors

Humans use multiple senses to navigate the social world, and the sense of smell is arguably the most underestimated one. An intriguing aspect of the sense of smell is its social communicative function. Research has shown that human odors convey information about a range of states (e.g., emotions, sickness) and traits (e.g., individuality, gender). Yet, what underlies the communicability of these states and traits via smell? We fill this explanatory gap with a framework that highlights the dynamic and flexible aspects of human olfactory communication. In particular, we explain how chemical profiles, associative learning (i.e., the systematic co-occurrence of chemical profiles with state- or trait-related information), and top-down contextual influences could interact to shape human odor perception. Our model not only helps to integrate past research on human olfactory communication but it also opens new avenues for future research on this fascinating, yet to date poorly understood, field.

Reply to Gangestad’s (2016) Comment on Wood, Kressel, Joshi, and Louie (2014)

Wood, Kressel, Joshi, and Louie’s (2014) meta-analysis of menstrual cycle influences on mate preferences identified three artifacts that influenced study findings: imprecise estimates of the fertile phase, decline over time, and publication effects. These artifacts also were evident in another recent meta-analysis by Gildersleeve, Haselton, and Fales (2014a). This consistent evidence of artifacts is not challenged by Gildersleeve et al.’s (2014b) failure to find another artifact–chasing significance levels. In addition, Wood et al. correctly coded the findings of Gangestad and colleagues’ research, given the variation in their reporting formats and inclusion criteria, which in some studies included only 54% of the sample. The controversy over menstrual cycle effects could be beneficial in increasing interest in publishing null results as well as in identifying evolutionary models that build on women’s capacity to regulate reproduction according to societal roles.