Contemporary and historical evidence to suggest that women's preference for age at birth of first child remains consistent across time.

Women's ability to reproduce is restricted by menarche and menopause. First children are, however, not typically born until some years after the onset of puberty. Other factors therefore contribute towards this delay. In this context, women's hips do not reach full adult form until they are in their mid-20s. Therefore, physiological and morphological factors appear to determine an optimum age-range for reproduction. The following studies were conducted in order to investigate this hypothesis. Study 1 asked nulliparous women questions about ages at which particular life events related to reproduction should ideally occur. This revealed their preferred age at birth of first child to be approximately 27 years old. Study 2 replicated these findings and further showed that women with children actually had their first child at a very similar age (27.93 [±0.79]). Findings from Study 3 were also remarkably consistent (28.15 [±0.39]). Study 4 examined the 1901 U.K. Census record and incorporated an analysis of the influence of wealth. Middle class women were on average 24.88 (±0.22) years old at the birth of their first child. Poor women were on average 23.50 (±0.20) years old. These figures at least approximate to findings from Studies 1-3, which is noteworthy given that modern contraceptive methods were not widely available at the time. It is concluded that female strategies to delay giving birth to their first child until they are of an age that approaches or coincides with their full hip maturation are enduring across time.

Evidence to suggest that women's sexual behavior is influenced by hip width rather than waist-to-hip ratio.

Waist-to-hip ratio (WHR) is an important ornament display that signals women's health and fertility. Its significance derives from human development as a bipedal species. This required fundamental changes to hip morphology/musculature to accommodate the demands of both reproduction and locomotion. The result has been an obstetric dilemma whereby women's hips are only just wide enough to allow the passage of an infant. Childbirth therefore poses a significant hip width related threat to maternal mortality/risk of gynecological injury. It was predicted that this would have a significant influence on women's sexual behavior. To investigate this, hip width and WHR were measured in 148 women (M age = 20.93 + 0.17 years) and sexual histories were recorded via questionnaire. Data revealed that hip width per se was correlated with total number of sexual partners, total number of one night stands, percentage of sexual partners that were one night stands, number of sexual partners within the context of a relationship per year sexually active, and number of one night stands per year sexually active. By contrast, WHR was not correlated with any of these measures. Further analysis indicated that women who predominantly engaged in one night stand behavior had wider hips than those who did not. WHR was again without effect in this context. Women's hip morphology has a direct impact on their risk of potentially fatal childbirth related injury. It is concluded that when they have control over this, women's sexual behavior reflects this risk and is therefore at least in part influenced by hip width.

Evidence to suggest that teeth act as human ornament displays signalling mate quality.

Ornament displays seen in animals convey information about genetic quality, developmental history and current disease state to both prospective sexual partners and potential rivals. In this context, showing of teeth through smiles etc is a characteristic feature of human social interaction. Tooth development is influenced by genetic and environmental factors. Adult teeth record environmental and traumatic events, as well as the effects of disease and ageing. Teeth are therefore a rich source of information about individuals and their histories. This study examined the effects of digital manipulations of tooth colour and spacing. Results showed that deviation away from normal spacing and/or the presence of yellowed colouration had negative effects on ratings of attractiveness and that these effects were markedly stronger in female models. Whitening had no effect beyond that produced by natural colouration. This indicates that these colour induced alterations in ratings of attractiveness are mediated by increased/decreased yellowing rather than whitening per se. Teeth become yellower and darker with age. Therefore it is suggested that whilst the teeth of both sexes act as human ornament displays, the female display is more complex because it additionally signals residual reproductive value.

Evidence to suggest that copulatory vocalizations in women are not a reflexive consequence of orgasm.

The current studies were conducted in order to investigate the phenomenon of copulatory vocalizations and their relationship to orgasm in women. Data were collected from 71 sexually active heterosexual women (M age = 21.68 years ± .52) recruited from the local community through opportunity sampling. The studies revealed that orgasm was most frequently reported by women following self-manipulation of the clitoris, manipulation by the partner, oral sex delivered to the woman by a man, and least frequently during vaginal penetration. More detailed examination of responses during intercourse revealed that, while female orgasms were most commonly experienced during foreplay, copulatory vocalizations were reported to be made most often before and simultaneously with male ejaculation. These data together clearly demonstrate a dissociation of the timing of women experiencing orgasm and making copulatory vocalizations and indicate that there is at least an element of these responses that are under conscious control, providing women with an opportunity to manipulate male behavior to their advantage.