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.学界目前围绕月经周期如何以及为何会影响女性对男性的吸引力这一议题仍存在持续争论。根据双重性假设（dual sexuality hypothesis），女性会与提供照料的男性建立伴侣绑定关系，同时在受孕期将择偶投入偏向拥有高适应性基因的男性，以此获取遗传收益。与之相对，承诺假设（commitment hypothesis）则提出，与主要伴侣形成的依恋联结，其作用是通过增强伴侣内部吸引力而非伴侣外部吸引力，来强化伴侣绑定关系。我们通过追踪女性在整个月经周期内对男性的日常性与情感吸引力，对这两种假设进行了检验。本研究采用了三类研究方法：（1）通过尿液黄体生成素（luteinizing hormone）检测确定排卵日；（2）将月经周期划分为五个阶段，以此明确区分出独特的围排卵期（peri-ovulatory phase）；（3）为每位参与者进行个体化的周期阶段划分。研究发现，女性的伴侣外性欲望在月经周期中期出现上升。相较于月经周期其他阶段，女性在经期从伴侣处获得并给予伴侣的照料更多。伴侣的性吸引力与双方的承诺程度并未对上述结果产生调节作用。研究结果既不支持双重性假设，也不支持承诺假设，这表明女性自我报告的性欲望并非严格依赖于周期性的激素变化。我们的研究结果更契合近期提出的「附产物（spandrel）」假设，该假设将周期阶段效应视为雌二醇水平升高所产生的非功能性附带产物。此外，我们发现，在通过黄体生成素检测确定排卵日期的前提下，有45%的排卵情况会被反向计数法误判，这提示在解读基于计数法的研究结果时需保持谨慎。