page_title: Extended female sexuality
section_title: Shifting mate preferences and behaviour across the ovarian cycle
hierarchical_section_title: Extended female sexuality / Explanations / Male assistance hypothesis / Shifting mate preferences and behaviour across the ovarian cycle
caption_attribution_description: Big Red Rooster ...
context_page_description: Extended female sexuality is where the female of a species mates despite being infertile. In most species, the female only engages in copulation when she is fertile. However, extended sexuality has been documented in old world primates, pair bonded birds and some insects. Extended sexuality is most prominent in human females who exhibit no change in copulation rate across the ovarian cycle.
  Although this behaviour incurs costs to females, such as energy and time, many researchers have proposed reasons for its existence. These hypotheses include the male assistance hypothesis, which proposes that females gain non-genetic benefits in exchange for sexual access. A sub-hypothesis of this is Hrdy's, proposing extended female sexuality as an adaptive process aiming to creating paternity confusion in males. Alternative hypotheses, classified as 'male-driven', claim that extended female sexuality occurs due to male adaptations, resulting from an inability to detect fertility status in females or to dampen immune responses against sperm. Finally, Spuhler's hypothesis suggests that the behaviour may have arisen as an incidental effect of larger adrenal glands in humans.
context_section_description: The final prediction of the male-assistance hypothesis has been extensively investigated. It predicts that females will exhibit differing mate preferences during fertile and non-fertile periods. Specifically, when fertile, the females will be sensitive to indicators of high genetic quality to increase the genetic quality of her offspring. Conversely, outside of the fertile period, females will show a preference for males who can provide resources for her and her offspring. In most species, males of higher genetic quality offer fewer non-genetic resources (such as shelter and food) than those of lower quality, so females are likely to choose different males at each stage.
  Evidence for this prediction has been found in many different species. In hens, those near peak fertility show a preference for socially dominant roosters with large combs. Larger combs have been reliably associated with health and offspring survival so reliably indicate the genetic quality of the rooster. In the non-fertile phases, hens mate more indiscriminately with less regard for the larger comb size. A similar pattern emerges in humans. A review of relevant studies on female preferences across the ovarian cycle reveals that women show a greater preference for masculine traits in fertile phases, especially for short term mating intention. This finding occurs across a variety of traits, such as masculine voices, body and facial features, scent, and behavioural displays. The level of masculinity acts as an indicator of genetic quality through its association with high testosterone. Similarly, women show a preference for higher levels of symmetry, which is thought to indicate underlying developmental stability. However, during infertile phases, women prefer males with lower masculinity and symmetry, as they tend to be more willing to offer material benefits.
  In addition to impacting mating preferences, females have been found to exhibit differing mating behaviour at different cycle stages. An analysis of 121 studies with female birds showed that most mate outside their pair bond at a higher rate when fertile, especially when the primary partner possesses indicators of low quality genes. During infertile phases, birds showed reductions in this behaviour, suggesting that the function of extended female sexuality is not to increase the genetic quality of offspring. In humans, females show increased motivation for mating with other males at mid-cycle without an accompanying increase in copulation with their long term partner, especially if the partner was less physically attractive.
caption: A rooster with a comb
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