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Psychological adaptation in females
Female sex-specific adaptations provide evidence of special design for the purpose of increasing fitness and in turn, reproductive success. For example, mate choice, rape aversion tactics and pregnancy sickness are all female-specific psychological adaptations, identified through empirical research, found to increase genetic contributions through survival and reproduction.

Mate-choice as an adaptation
A psychological adaptation for the purpose of reproductive success can be seen in female mate choice. David Buss, an evolutionary psychologist, examines the fundamental principles of selection pressures that create human mate preferences in his contribution to the publication The Adapted Mind. Females have evolved psychological procedures that affect mating decisions in relation to certain male physical attributes and behaviours. Robert Trivers, an evolutionary biologist, outlines the evolutionary basis of these preferences in relation to parental investment and sexual selection. He proposes that females have adapted a preference to mate with males who display both an ability and willingness to invest vital resources for the survival of the female and her offspring. Research suggests females are able to use external cues displayed by males such as territory or physical possessions. For example, women are able to evaluate the long-term presence of testosterone in men by observing facial testosterone cues. Testosterone stimulates craniofacial development and results in a squarer jaw and consequently, a more masculine appearance. Women in the fertile phase of their menstrual cycle perceive masculine faces as healthier and more attractive than feminine male faces. Females show a psychological adaptation to detect mate quality using these hormonal cues which display the male’s fitness and reproductive value. Males who display testosterone cues show a female that they are able to offset the high physiological costs such as immunosuppressant effects.

Rape avoidance
Research proposes that women have evolved psychological mechanisms specifically designed to motivate rape-avoidance behaviours or strategies. This is because rape poses severe costs for the female such as pregnancy, physical harm, injury or death, relationship abandonment and self-esteem depletion. The greatest cost to the female is the circumvention of her mate choice, which threatens reproductive success, resulting in the possession of adaptations in response. Evidence suggests that a number of female-specific traits have evolved in order to reduce the risks associated with experiencing rape. The body-guard hypothesis proposes that rape-avoidance drives women’s mate preferences for physically or dominant males. Women may also form groups with men and women as a protective alliance against potential rapists. Psychological pain experienced following rape is also identified as an adaptive process designed to focus the female on the social circumstances surrounding the rape for future prevention. Evidence for this as an adaptation can be seen in reproductive-aged women who are found to experience more psychological pain following rape due to an increased risk of conception. Research also suggests that women in the fertile phase of their menstrual cycle perform fewer risky behaviours that could potentially result in the risk of rape. Women’s capacity to resist rape also changes relative to their menstrual cycle; females in the fertile phase show an increase in handgrip strength when placed in a threatening, sexually coercive scenario. Susceptibility to signs of a male’s coerciveness is also identified to be better in fertile women.

Pregnancy sickness
One psychological adaptation found solely in women is pregnancy sickness. This is an adaptation resulting from natural selection for the purpose of avoiding toxic-containing foods during pregnancy. Margaret Profet, an evolutionary biologist, provides evidence for this adaptation in a literature review on pregnancy sickness. Particular plant foods, whilst unharmful to adults, can contain toxins (e.g. teratogens) that are dangerous for developing embryos and can potentially cause birth defects such as facial asymmetry. Evidence lies in the finding that women who experience more extreme cases of pregnancy sickness tend to be less likely to miscarry or have babies with birth defects. This fits the criteria for an adaptation as it enhances fitness and increases reproductive success – it results in greater fertility of the mother and contributes to the health of the developing embryo. Researchers dispute whether this is actually a psychological adaptation, however evidence advocates it is the result of strong selective pressures in our hereditary past. For example, the toxins are found only in natural wild plant foods, not processed foods in our modern-day environment. Furthermore, pregnant women experiencing sickness have been found to avoid particular bitter or pungent smelling foods, potentially containing toxins. Pregnancy induced sickness only typically occurs 3 weeks after conception, around the time when the embryo has started forming major organs and is therefore at the highest risk. It is also a cross-cultural universal adaptation, a suggestion it is an innate mechanism.