sexual orientation. Furthermore, the majority of homosexual women who previously identified as a different sexual orientation identified as heterosexual; whereas for males, the majority previously identified as bisexual, which the authors believe support the idea of greater fluidity in female sexuality. Females also report having identified with more than one sexual orientation, more often than males and are found to have higher levels of sexual orientation mobility. Females also report being bisexual or unsure of their sexuality more often than males, who more commonly report being exclusively gay or heterosexual. Over a six-year period, women have also been found to display more shifts in sexual orientation identity and were more likely to define their sexual orientation with non-exclusive terms. The social constructivist view suggests that sexual desire is a product of cultural and psychosocial processes and that men and women are socialized differently. This difference in socialization can explain differences in sexual desire and stability of sexual orientation. Male sexuality is centered around physical factors, whereas female sexuality is centered around sociocultural factors, making female sexuality inherently more open to change. The greater effect on female sexuality in 1970s sexual revolution shows that female shifts in sexual orientation identity may be due to greater exposure to moderating factors (such as the media). In western culture, women are also expected to be more emotionally expressive and intimate towards both males and females. This socialization is a plausible cause of greater female sexual fluidity. Whether female sexuality is naturally more fluid and therefore changes from social factors or social factors cause female sexuality to be less stable is unknown. An evolutionary psychology hypothesis proposes that bisexuality enables women to reduce conflict with other women, by promoting each others' mothering contributions, thus ensuring their reproductive success. According to this view, women are capable of forming romantic bonds with both sexes and sexual fluidity may be explained as a reproductive strategy that ensures the survival of offspring. A longitudinal study concluded that stability of sexual orientation was more common than change. Gender differences in the stability of sexual orientation may vary by subgroup and could possibly be related to individual differences more than gender-wide characteristics. Youth (age 14–21) One study that did compare the stability of youth sexual orientation identity across genders found results opposite to most done with adult samples. The study compared non-heterosexual male and female sexual orientation over a year and