Jones et al. (2008), focused on women's preferences for masculinity, apparent health and self-resemblance and found that it varies across the cycle. They explained that the function of the effects of menstrual cycle phase on preferences for apparent health and self-resemblance in faces is to increase the likelihood of pregnancy. Similarly, females prefer the scent of symmetrically faced men and men with masculine faces during fertile phases as well as stereotypical male displays such as social presence, and direct intrasexual competitiveness. During the follicular phase (fertile), females prefer more male's traits (testosterone dependent traits such as face shape) than when in non-fertile phase. Those findings have been found in the voice, showing that females' preferences for more masculine voices over feminine voices increase the fertile phase of the menstrual cycle. But not only females' preferences vary across cycle, their behaviours as well. Effectively, men respond differently to females when they are on ovulatory cycle, because females act differently. Women in the ovulatory phase are flirtier with males showing genetic fitness markers than in low fertile phase. It has been shown in some studies that women high in estrogen are generally perceived to be more attractive than women with low levels of estrogen, based on women not wearing make-up. High estrogen level women may also be viewed as healthier or to have a more feminine face. Similarly, a study investigated the capacity of women to select high quality males based on their facial attractiveness. They found that facial attractiveness correlated with semen quality (good, normal, or bad depending on sperm morphology and motility). The more attractive a man's face is, linked to his sperm being of better quality. Sexual ornamentation Sexual ornaments are seen in many organisms; in humans, females have sexual ornamentation in the form of breasts and buttocks. The physical attraction to sexual ornaments is associated with gynoid fat, as opposed to android fat, which is considered unattractive. In human females, proximate causes of the development of sexual ornaments are associated with the predominance of estrogen in puberty. The activation of estrogen receptors around the female skeletal tissue causes gynoid fat to be deposited in the breasts, buttocks, hips and thighs, producing an overall typical female body shape. Specifically, female breasts are considered more attractive when symmetrical, rather than asymmetrical, as this is thought to reflect good developmental stability. Sexual ornaments are considered attractive features as they are thought