Spring, and a young man's thoughts turn to . . . chest hair. Also, that of the back, the belly, the shoulder and legs.

Spring, and a young man's thoughts turn to . . . chest hair. Also, that of the back, the belly, the shoulder and legs.

Summer beckons. The pool, the beach. Skin revealed. Worries: Slack gut, man-boobs, back fur, being regarded as a metrosexual. You don't want to be too concerned about your looks, and yet you don't want to be so hirsute that some guy comes up to you at the pool, going: "Burt? ... Burt Reynolds?"

"Body hair is a major category of what guys worry about," says Glenn O'Brien, author of "The Style Guy" and a column by that title for GQ magazine. "It's in the realm of 'What color socks match my shoes and pants?' I could write a column on it every month."

Guydom, manhood, it's all different now. The range of socially acceptable grooming keeps expanding, like the universe. Facial washes, toner, skin cream. Wear an earring? Sports watch, dress watch? A good cologne, no split ends, check the nasal hair, SPF 15.

And now, body hair.

It's not entirely serious, but it's not entirely flip, either. Guys used to attract women with their confidence, muscle, power, fearlessness. Now you've got to have a position on shoulder sprigs.

"We have about seven or eight gentlemen come in every day for back waxing," says Jodi Ross, assistant manager at the Grooming Lounge, a high-end salon for men in downtown Washington, D.C. "There are fewer who request chest waxing, but there's a definite interest there as well."

You might be thinking this is a fad. One of those alleged trends like feminists burning their bras back in the day, or maybe like the mullet haircuts on guys in the 1980s.

Maybe some silliness for jocks, swimmers, celebrities, LL Cool J, Daniel Craig, David Beckham, Michael Phelps, the Rock; yeah, sure, but not the guy next to you in the stands at the ballgame.

This is not so.

Consider:

Last May, Philips Norelco rolled out the $34.99 Bodygroom BG 2020, a shaver designed to trim or shave body hair. "It blew our sales projections out of the water," says Shannon Jenest, a spokeswoman for the company. "It took off in ways we couldn't imagine. We tripled our original forecast by the end of the year." Men's Health, a magazine aimed at working guys who work out, has had exactly two guys with chest hair on the cover in the last 17 years, according to Brian Boye, the magazine's fashion and grooming editor. Last summer, a guy named Brett Marut in Santa Monica, Calif., came out with a thing called Mangroomer. It's essentially a shaver on a stick, designed to enable you to reach around and shave your back. He priced it at $39.95, looking to appeal to guys in Flyover, America, who were too self-conscious to go to a salon to get it done, or even let their friends know they were trying it out. He didn't have much money, so he just put a couple of ads on Internet search engines. It was an instant hit, blossomed at online retailers and, 10 months later, Mangroomer is in every Bed Bath & Beyond in the country.

"Chest hair — waxing, shaving it — it's like an option that some guys like and some guys don't," Marut says. "But who goes around saying, 'I really like my back hair'?"

There's also Nair for Men, which sells for about $5 and promises to get rid of hair in four minutes by rubbing a cream on it.

Waxing, shaving, depilating, lasering men's body hair: It's all part of the beautification of the male animal, an aesthetic that genuflects before the ancient Greeks. The surviving statuary shows highly idealized men, with hair on the head, and perhaps the face, but entirely smooth-chested. The beauty was in the muscle, the tone, the curve of the triceps of the extended arm, the triple cords of the abdominal muscles.

Hair obscured the clean-lined beauty of it all. This idealized image gained permanent Western footing in the Renaissance, when paintings and sculpture — right down to Adam on the Sistine Chapel ceiling, the very first man — was pictured as devoid of chest hair.

In real life, it is boys, not men, who are devoid of body hair, and for ages one sign of adult male virility was chest hair. To be devoid was to be effeminate. This continued in Western and American pop culture right through the last century. Men never considered grooming below the neck.

Nobody has an exact beginning point, but bodybuilders, starting with, say, Jack LaLanne in the 1940s, would hearken to that Grecian ideal, shaving their bodies for competition, the better for judges to appreciate every oiled and sculpted pec. There's a picture of LaLanne posing beachside about 1950. He looks like he's made out of marble. The only hair visible is on his head.

By the early 1980s, the hairless chest and back was catching on with gay guys. Like earrings, it began to cross over to fashion-conscious straight men, athletes and celebrities, and then into the mainstream.

It's also driven by dames. Girlfriends and wives. Everyone interviewed for this story said one of the main reasons guys were doing something about their body hair was because their significant other had requested it.

Philips Norelco says 57 percent of Bodygroom consumers surveyed said they made their purchase because they "or their significant other" prefer the hairless look. (We also duly note that Playgirl magazine reported in 2005 that of 2,000 women surveyed, 47 percent approved of chest hair, 53 percent did not, and 73 percent said they wanted a man who is "rough around the edges." Go figure.)

Also, it was universally agreed by everyone interviewed that back hair for anyone younger than your grandpa has gone the way of the uni-brow and ear hair — it's gotta go, dude. A social embarrassment. Keep it at your own peril.

Chest hair is a matter of choice.

O'Brien offers this guide:

"If your chest hair alters the way your shirt fits, it should be reduced. If your wife or girlfriend complains about it, it should be reduced."

This is good advice. This is sensible. This is something to keep guys looking like they've got a little something going on, that they're up on things, which is sort of what style is, which is sort of what guys want to have without looking like they're trying to have it.