Visual, olfactory, and vocal cues to fecundity in human females

在大多数哺乳动物（胎盘）雌性动物中，发情周期包括由生殖激素引起的反复出现的生理变化。在动物中，这一独特的生育阶段通常与对雄性的感知能力和接受能力增强有关，并且经常与某些感官线索有关。有观点认为，相比之下，人类女性在其生殖周期中已经失去了这样一个独特的生育阶段（Jolly, 1972; Alexander & Noonan, 1979; Alexander, 1990），因为她们没有显示出生育状态的明确信号。然而，最近来自人类性行为进化研究的证据表明，必须重新考虑这种“隐藏排卵”的观点，因为有证据表明，存在某些视觉、嗅觉和声音线索，作为女性生育能力的间接标志（Thornhill & Gangestad, 2008）。进化心理学家认为，男性在进化过程中已经发展出了认知适应能力，因此他们判断那些与女性生育能力有关的感官线索有吸引力（Law-Smith等人，2006;Singh & Bronstad, 2001; Puts, 2005）。如果人类女性的生育能力并非完全被隐藏，而是通过感官线索发出信号的假设是正确的，那么男性应该能够根据视觉、嗅觉或声音线索（或所有这些线索）分辨出有生育能力和没有生育能力的女性。到目前为止，在检验这一论断的研究中，主要的样本是大学年龄的年轻女性，因此，男性对这些信号的感知在生育前、生育期和生育后的女性中是否存在差异还有待调查。在这个项目中，我们测试了三个年龄组（即生育前、生育期和生育后的女性）男性对女性视觉、嗅觉和声音线索的感知差异的假设。我们假设男性对女性的面部表情、体味和声音的变化很敏感，所有这些都与女性的生育能力有关。因为性选择倾向于那些能够发现女性生育能力的男性，从而确定她们是潜在的伴侣，育龄女性应该比育龄前和育龄后的女性得到更高的吸引力判断，这在所有三种感官质量上都是正确的。

The oestrus cycle comprises the recurring physiologic changes that are induced by reproductive hormones in most mammalian (placental) females. In animals this distinct phase of fertility is typically associated with enhanced proceptivity and receptivity to males and frequently linked to certain sensory cues. It has been argued that human females, in contrast, have lost such a distinct phase of fertility within their reproductive cycle (Jolly, 1972; Alexander & Noonan, 1979; Alexander, 1990), as they do not display clear signals of fertility status. However, recent evidence from the evolutionary study of human sexual behaviour suggests that this view of a 'concealed ovulation' must be reconsidered, as evidence suggest that there are certain visual, olfactory and vocal cues that serve as indirect signs of a woman's fertility (Thornhill & Gangestad, 2008). Evolutionary psychologists argue that men have developed cognitive adaptations throughout evolution, such that they judge those sensory cues attractive, which are linked to a woman's fertility (Law-Smith et al., 2006; Singh & Bronstad, 2001; Puts, 2005). If the hypothesis that human female fertility is not entirely concealed, but also signalled via sensory cues, were true men should be able to discern fertile from nonfertile women based on either visual, olfactory or vocal cues (or all of them). So far, the predominant samples in studies testing this assertion have been young women at College age, thus it remains to be investigated whether differences in men's perceptions of these signals in pre-reproductive, reproductive, and post-reproductive women exist. In this present project we test the hypothesis of differences in men’s perception of women's visual, olfactory and vocal cues of three age cohorts (i.e. pre-reproductive, reproductive, and post-reproductive women). We hypothesize that men are sensitive to the variation in women’s facial appearance, body odour and voices, all of which are linked to a woman’s fertility. Because sexual selection favours males who are able to detect fertility in women, and thus identify them as potential mates, women at reproductive age should receive higher attractiveness judgements than pre-reproductive and post-reproductive women, this being true for all three sensory quality.