Since there is no reliable medical measure of virginity, the meaning of virginity is primarily a social construct. Many cultures place a high value on virginity, especially for women. However, there are many different definitions of virginity. As Western culture continues to broaden its sexual horizons, the meaning and significance of virginity will likely change and adapt. History In ancient Greece and Rome, the term virgin was used to describe a woman who was strong and independent and was not interested in relationships with men. Athena and Artemis (also called Diana) were powerful virgin goddesses. The Christian church to this day encourages all people to remain virgins until they are married and require that nuns and priests remain celibate. Some cultures may not place much significance in virginity, or they may celebrate and ritualize the loss of virginity. The hymen Females are born with a hymen, a thin membranous wall inside the vagina. The hymen often tears or breaks during a female's first sexual intercourse, resulting in minor bleeding. However, some hymens are very elastic, and may not break even after vaginal intercourse, or the hymen may be broken accidentally by tampon use, masturbation or vigorous exercise. Therefore, the presence or absence of a hymen is not an accurate indication of virginity Gender differences Men and women tend to regard virginity in different ways. According to a 2005 study by Dr. Laura Carpenter of Vanderbilt University, females are more likely to think of virginity as a gift to save and give only to a special person, while males tend to think of virginity as a stigma, something to get rid of as soon as possible. Society generally reinforces these viewpoints: women with multiple sexual experiences are looked down upon as being promiscuous, while men with multiple sexual experiences are thought of as virile. However, the definition of sex and virginity is fluid, and different social circles may not subscribe to this gender dichotomy. The meaning of sex The meaning of virginity depends on the meaning of sex. Socially, many people only consider penis-in-vagina intercourse to be "real" sex, and therefore would define virginity as to whether or not a person has engaged in this activity. However, not all couples enjoy penetrative sex, and may base their virginity or lack thereof on other sexual activities, such as oral sex or heavy petting. Sex may also be defined by consent, and a person who has been raped or sexually abused may still be considered a virgin. Homosexuality Since heterosexual sex is often defined as penis-in-vagina intercourse, some people apply a similar construct to homosexual sex, and may say that a gay man is a virgin until he has had penetrative anal sex and a lesbian is a virgin until she has been vaginally penetrated by fingers or an object. However, many sexually progressive people reject this heteronormative definition of sex and virginity, and instead may define sex as any genital contact, or as any activity that is in pursuit of an orgasm. They may also reject the notion of virginity completely as being irrelevant.