Data from: Women's emotional and sexual attraction to men across the menstrual cycle

There is ongoing debate about how and why the menstrual cycle affects women’s attraction to men. According to the dual sexuality hypothesis, women form pair-bond relationships with men who provide care but also obtain genetic benefits by biasing mating effort towards men with high-fitness genes during the fertile phase. By contrast, the commitment hypothesis proposes that attachment bonds with primary partners function to strengthen pair-bond relationships by enhancing in-pair attraction at the fertile phase, rather than extra-pair attraction. We tested these hypotheses by measuring women’s daily sexual and emotional attraction towards men over the whole menstrual cycle. We employed (1) a urinary luteinizing hormone test to determine the day of ovulation, (2) a five-part classification of menstrual cycle that identifies a distinct peri-ovulatory phase, and (3) individualized phase identification for each participant. There was a mid-cycle rise in extra-pair sexual desire. Women gave and received more care from partners during the menstrual than the mid-cycle phases. Partner’s sexual attractiveness and mutual commitment did not moderate these findings. The results do not support either the dual sexuality or commitment hypotheses, and imply that female self-reported sexual desire is not strictly dependent on cyclic hormonal changes. Our results are more consistent with a recently proposed `spandrel’ hypothesis, positing cycle phase effects as a non-functional by-product of raised estradiol. Additionally, we found that, with the date of ovulation estimated by luteinizing hormone tests, 45% of ovulations were misclassified by the backward counting method, which urges caution in interpreting results based on counting methods.目前学界关于月经周期（menstrual cycle）如何且为何会影响女性对男性的吸引力，仍存在持续争论。根据双重性假说（dual sexuality hypothesis），女性会与提供照料的男性建立伴侣绑定关系，同时在受孕期（fertile phase）将择偶精力偏向携带高适合度基因（high-fitness genes）的男性，以此获得遗传收益。与之相对的承诺假说（commitment hypothesis）则提出，女性与主要伴侣的依恋绑定，可通过增强受孕期的伴侣内吸引力（in-pair attraction）而非伴侣外吸引力（extra-pair attraction）来强化伴侣绑定关系。 本研究通过追踪女性在完整月经周期内对男性的日常性吸引力与情感吸引力，对上述两种假说展开检验。研究采用了三项方法：（1）尿黄体生成素（urinary luteinizing hormone）检测以确定排卵日；（2）采用月经周期五阶段分类法，以明确区分独特的围排卵期（peri-ovulatory phase）；（3）为每位参与者实施个体化周期分期（individualized phase identification）。 研究结果显示，女性的伴侣外性欲（extra-pair sexual desire）在月经周期中期出现显著上升。相较于月经周期其余阶段，女性在经期从伴侣处获得的照料以及向伴侣提供的照料均更多。伴侣的性吸引力与双方的相互承诺均未对上述研究结果产生调节效应。 本研究结果既不支持双重性假说，也不支持承诺假说，这表明女性自我报告的性欲并非严格依赖于周期性激素变化。我们的研究结果更契合近期提出的拱肩假说（spandrel hypothesis），该假说将周期阶段效应视为雌二醇（estradiol）水平升高所带来的非功能性副产物。 此外，本研究发现，在通过黄体生成素检测确定排卵日期的前提下，有45%的排卵情况被逆向计数法（backward counting method）误判，这提示未来基于计数法的研究结果解读需格外审慎。