But women sport a stark-naked mons veneris for many reasons, ranging from the practical to the provocative. Herbenick's explanation is a tame one: She thinks it's mainly a response to skimpy clothing trends. "Our underwear today is a lot smaller than women's underwear was 20 years ago," she says. "And if you have hair sticking out the sides of your underwear, that's just kind of, like, unkempt."
Low-slung pants, too, may be a factor: "Certainly when I think of the younger version of Britney Spears and the extremely low-cut jeans she would wear, I remember thinking, If she had pubic hair you would be able to see it," she says.
Pinto's reasoning, too, is more sensible than scandalous: She just feels cleaner down there.
"It could be attributed to visual pornographers' desire to infantilize women, or simply to make genitalia more visible to the camera."
"I work out a lot. I get sweaty," she explains calmly. "And it starts to smell when you've got hair down there. So yeah, it hurts, but I just feel so much cleaner."
Pinto, who's candid about her active sex life, points out that she's never waxed at the request of a boyfriend or a partner. "I did it the first time for me," she says, "and I still do it for me." Pinto was 17 when she first waxed it all off.
Though Pinto says sex has never felt any different to her without pubic hair ("Once we get going, who cares?" she says with a laugh), there certainly remains a sexual motive for taking it all off: Drawing back the curtain of pubic hair exposes the clitoris, the labia and the vagina for plain viewing. There's a tactile element, too: As one elated young husband named Mark explained to Glamour in 2009, "The skin down there is protected -- it never really touches anything, it never sees the sun -- so it's ridiculously soft.
"You can't really tell how soft it is until a woman waxes. Oh my God, you can't believe how soft it is when you wax," 28-year-old Mark gushed. "It's extremely, extremely soft, so it feels great when you have sex."
Pinto's past boyfriends, she says, would wholeheartedly agree. "Once, I started dating someone when I hadn't waxed in a while," she says, "And then when I did, he went, Oh! This is awesome! Why didn't you do this before?!"
"That was my senior year of high school," she adds. "So every month I would text him, 'Guess who's getting a wax!' And he'd be like, 'Smiley face, so excited!'"
Many men, like Bob Fitzpatrick, a finance student at the University of Michigan, are more likely to perform oral sex on a female partner if she has no pubic hair.
"If she's seeking for you to pleasure her and you have pubic hairs in your mouth, you're not going to be pleased with that," the 21-year-old says. Fitzpatrick, a bright, chatty Lake Forest, Illinois, native who's paired off with a casual-but-exclusive significant other, says he prefers a clean-shaven or fully waxed mons pubis, and giggles as he recalls one particularly dismaying encounter. "I was like, Oh no, five o'clock shadow?! This is gonna be itchy on my face!"
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Although sex, hygiene, and clothing are all contributing factors, Fitzpatrick, Herbenick, and Pinto all agree that there's one main driving force behind America's villainization of pubic hair: pornography.
When a team of researchers from George Washington University took a closer look at Playboy's representations of women's genitalia throughout the years, they found that in issues dating from the magazine's inception in 1953 up through the 1970s and '80s, more than 95 percent of the centerfolds and naked models sported full, apparently natural pubic hair.
In the late 20th century, though, that changed. As Joseph Slade, professor of media and culture at Ohio University, puts it, the media legitimized voyeurism and turned it into a way of life; suddenly, porn viewers wanted to see everything more deeply and without the veil of hair. Thus, Playboy's love affair with the au naturel look faded: By the 1990s, more than a third of the models appeared to have removed some of their pubic hair. And in the new millennium, less than 10 percent of nude models now sport the full pubic bush, while a third remove their hair partially and one-quarter remove it completely. Playboy has trimmed down the standard from the un-modified, detail-obscuring "fur bikini" it helped popularize in the 1960s to the vanishing act it promotes today.
Hugh Hefner's magazine, however, isn't the only supporter of the tress-less treasure chest. Rather, says Slade, genital alopecia seems to have hit the entire adult entertainment industry. "Depilation took hold in visual porn in the 1990s, though some actresses trimmed for movies before then," Slade says. "It was easier to keep crotches cleaner on the set. But certainly the practice is widespread in video porn today. Enough so that backlash has created a niche fetish for 'full bushes.'"
But while the sleek, slick, bare labia majora is more common in visual porn today than ever before, the stylized hairless vulva has actually been around for centuries. According to Slade, as far back as the 15th century, women -- especially prostitutes -- often shaved their pubic hair to avoid lice infestation, which is where having a muff may have picked up its stigma of being "unclean." In the years following, medieval and classical European sculptors and painters omitted pubic hair from depictions of female nudes; In fact, the notion of pubic hair in general was so unholy that every last naked prophet on the Sistine Chapel ceiling is completely hairless below the neck. But life didn't dare imitate art -- at least, that is, not until Playboy.
Slade cites two potential reasons for porn's fixation on the bare vagina. "It could be attributed to visual pornographers' desire to infantilize women," Slade says, "or simply to make genitalia more visible to the camera. Male porn stars often shave their pubic hair for that purpose, too."
Many feminists understandably take umbrage at the first, Slade says. "Bare pubic areas are most common in videos advertised as featuring young women, because it does infantilize them or make them look pre-pubescent." It's less common, he says, in porn featuring MILFs (American Pie's now-famous acronym for "mothers I'd like to fuck"), because mature age is the appeal.