men and women's faces was wider eyes relative to facial height for women, and this trait consistently predicted attractiveness ratings for women. In Arabian society in the Middle Ages, a component of the female beauty ideal was for women to have dark black eyes which are large and long and in the shape of almonds. Furthermore, the eyes should be lustrous, and they should have long eyelashes. A source written in 1823, said that a component of the Persian female beauty ideal was for women to have large eyes which are black in color. In Persian literature, beautiful women are said to have eyes that are shaped like almonds. In Chinese, the phrase "lucent irises, lustrous teeth" () is used to describe a beautiful woman with "clear eyes" and "well-aligned, white teeth", and the phrase "moth-feeler eyebrows" () is used to denote a beautiful woman by describing her eyebrows as being thin and arched like moth antennae. In the Chinese text The Grotto of the Immortals () written during the Tang dynasty period, narrow eyes were the preferred type of eyes for women, and, in the Chinese text Jeweled Chamber Secrets () from the Six Dynasties period, the ideal woman was described as having small eyes. In Japan, during the Edo period, one piece of evidence, the appearance of the "formal wife" of Tokugawa Iesada as determined by "bone anthropologist" Suzuki Hisashi, indicates that large eyes were considered attractive for women, but, another piece of evidence, the 1813 Japanese text Customs, Manners, and Fashions of the Capital (), indicates that large eyes were not considered attractive for women. Breasts Research has shown that most heterosexual men enjoy the sight of female breasts, with a preference for large, firm breasts. However, a contradictory study of British undergraduates found younger men preferred small breasts on women. Smaller breasts were widely associated with youthfulness. Cross-culturally, another study found "high variability" regarding the ideal breast size. Some researchers in the United Kingdom have speculated that a preference for larger breasts may have developed in Western societies because women with larger breasts tend to have higher levels of the hormones estradiol and progesterone, which both promote fertility. A study by Groyecka et al., in which they examined Poles and Yali of New Guinea, demonstrated that men's judgements of breast appearance is affected by the occurrence of breast ptosis (i.e., sagginess, droopiness). Greater breast ptosis (more