Male-male
In premodern societies, including ancient Greece and premodern Japan, anal sex was associated with male-male paederastic relationships. Manuscripts and art from those periods depict anal sex as the main or only sexual activity that occurred in such relationships.
In modern times, particularly in Western cultures, anal sex has been popularly associated with gay and bisexual men. In particular, anal sex has been associated with the spread of HIV, especially in early years of the discovery of the disease. This resulted in gay bathhouses in some American cities being shut down by public-health authorities.
Among gay men who have anal sex, some consistently take the top (insertive) or bottom (receptive) role, but this is not always the case: some men who have anal sex act as both top and bottom at different times. This is known as "versatile" or "switch".
Male-female
In several cultures female receptive anal intercourse in a heterosexual context is widely accepted, especially as there is very low risk of unwanted pregnancy via unprotected anal intercourse (though this is not an absolute guarantee, since semen can leak from the anus, across the perineum, and enter the vagina). Anal sex is even sometimes seen as preserving female virginity, because it leaves the hymen intact. Another reason is that the anus is considered to be tighter than the vagina, therefore yielding more tactile pleasure for the penis. The Renaissance poet Pietro Aretino strongly recommended the practice of anal sex in his Sonetti Lussuriosi (Lust Sonnets).
Anal sex and female virginity
Though more often applied to first penetration, the concept of "technical virginity" is sometimes conceived of as resting solely on vaginal penetration. In Norman Mailer's novel Harlot's Ghost, a character states that in Italy, an unmarried woman had to be "a maiden before and a martyr behind," which implied that such women often resorted to anal sex, and anal sex was consistently painful.
In other cases first anal intercourse is concieved of as ending a separate virginity from first vaginal intercourse,with varying degrees of seriousness. In a Rolling Stone interview comedian Sarah Silverman joked: "I didn't lose my virginity until I was twenty-six. Nineteen vaginally, but twenty-six what my boyfriend calls 'the real way.'
Frequency
Determining the proportion of people that engage in anal sex, and the frequency with which they do so, is rather difficult. Sexual surveys tend to reflect whether those surveyed have ever had anal sex, or whether they have had anal sex in the last year, instead of distinguishing between those who have tried it one or a few times and those who regularly have anal sex.
The Gay Urban Men's Study (P.I. Stall, UCSF) and the Young Men's Study (YMS, PI Osmond/Catania, UCSF), indicate that 50% of men surveyed engage in anal sex. The Laumann study claims that 80% of gay men practice it, while the remaining 20% never engage in it at all.
Edward O. Laumann's The Social Organization of Sexuality: Sexual Practices in the United States found that about 20% of heterosexuals have engaged in anal sex, and sex researcher Alfred Kinsey found that number to be closer to 40%. More recently, a researcher from the University of British Columbia in 2005 put the number of heterosexuals who have practiced anal sex at between 30% and 50%. Most recently, a 2006 survey conducted by the Centers for Disease Control determined that the incidence of anal relations in the heterosexual population is on the increase. The survey showed that 38.2 percent of men between 20 and 39 and 32.6 percent of women aged 18 to 44 had engaged in heterosexual anal sex; in 1992 a similar survey found that only 25.6 percent of men 18 to 59 and 20.4 percent of women 18 to 59 had.