It’s sometimes taken for granted that bluegrass is an ancient musical form handed down and pristinely preserved in the hills and hollers—so old that no one who originally played it could still be alive—and that its practitioners and audiences hold to tradition with such a white-knuckled grip that nothing new could ever make inroads. And that perspective makes some sense in light of the fact that the ’90s—at least according to VH1’s I Love the ’90s series—are already retro.

But in reality, 1946—a mere two generations back—is often considered the birth year of the bluegrass style, making it old (barely older than rock ’n’ roll, in fact) but definitely not ancient. When bluegrass started, it was a hot new innovation—an energetic synthesis and transformation of acoustic styles in the hands of Bill Monroe, Earl Scruggs, Lester Flatt and others. (For the record, Scruggs is still alive.) And, like rockabilly and Western swing, it was an alternative to country music that’s never been fully absorbed into the mainstream. But, unlike those two genres, bluegrass still has a healthy, ever-evolving scene with a life of its own.

In some ways, bluegrass lurks at the edge of musically savvy twenty- and thirtysomething consciousness (not that that’s anything new for the genre). Annual bluegrass and folk festivals have dotted the landscape for decades, but Bonnaroo is a nearby example of the capability of bluegrass acts such as the Del McCoury Band to hold their own alongside those who plug in their guitars—and the fiery bluegrass instrumentals are far more focused than any jam-band noodling. Plenty of indie acts have flirted with the old-time aesthetic of late—Sufjan Stevens’ banjo playing and the twin fiddling on Bright Eyes’ Cassadaga are cases in point. Old Crow Medicine Show may not exactly play bluegrass, but the band’s raucous, punkish take on string-band music has found an appreciative young audience.

Creative tension between old and new in bluegrass works against homogeneity. The music might be traditional (meaning that it sticks fairly close to Bill Monroe’s original hard-driving formula of mandolin, fiddle, banjo, guitar and bass with high lonesome harmonies), pop-smoothed (like Alison Krauss and Union Station) or a progressive fusion of bluegrass and outside influences (i.e., newgrass). The variety extends to the kinds of people drawn to the music, from far right to far left on the political spectrum, and the songs they sing—from corn-liquored rowdiness to gospel fervor.

When the International Bluegrass Music Association makes its annual descent upon downtown Nashville for the World of Bluegrass—a weeklong conference with an awards show and showcases day and night—some surprisingly good musical moments occur in hotel hallways when unknowns spontaneously whip out their instruments and play on the spot. It just goes to show that there’s room for both professionalism and DIY.

Among more traditional approaches to bluegrass, rural-Kentucky-born vocalist Bradley is the epitome of a glitz-less, down-to-earth performer. A former member of the New Coon Creek Girls who now fronts her own band, she takes the stage unapologetically as-is.

“When I started out I just wore what I wore to school basically,” says Bradley. “Of course, my mother just couldn’t hardly deal with that—‘we got to doll you up.’ She’d try her best—bless her heart—with the best intentions. And then when I came to Renfro Valley [the Renfro Valley Barn Dance is a long-running musical variety show—Kentucky’s Grand Ole Opry], I had big old earrings that gave me a headache, and high heels. I couldn’t hardly walk in them. It was always against my nature. That just wasn’t me. It’s not really a rebellion. It’s just sometimes you’ve got to be who you are.”

Bradley’s lure is her voice—a pure, pleasing instrument, gently swooping, trilling and bending notes with a natural emotiveness to rival blues and soul singers. In fact, she recorded a double-time version of Ann Peeble’s classic soul lamentation “I Can’t Stand the Rain” for her most recent album, Catch Tomorrow. It’s one of many covers Bradley has handpicked from decidedly non-bluegrass sources.

“ ‘I Can’t Stand the Rain,’ that’s bluegrass lyrics—‘I can’t stand the rain against my window bringing back sweet memories,’ ” says Bradley. “That’s a Bill Monroe song right there.” She’s even included a U2 song in her repertoire (“I Still Haven’t Found What I’m Looking For” on 1997’s East Kentucky Morning), which suggests that the relationship between bluegrass and other forms of popular music is more fluid than one might think.

At the opposite end of the traditional bluegrass spectrum are Cherryholmes, a six-member family band who quickly rose to popularity with their polished live show, incorporating dressed-up stage clothes, Irish stepdance, joke-telling and family patriarch Jere Cherryholmes’ jovial emceeing. Youthful vitality didn’t hurt either. Half of the four Cherryholmes kids—Cia Leigh, B.J., Skip and Molly Kate—still have “teen” attached to their ages.

As their two most widely released records, 2005’s Cherryholmes and this year’s Cherryholmes II: Black and White, attest, they’re all skilled musicians now—and virtuosity is a prized commodity in bluegrass. But they’d only just picked up their instruments when Cherryholmes (then called Cherryholmes Family Band) got their first gig eight years ago.

“It’s kind of interesting, because we were forced into something out of necessity and it turned out to be something that became an actual persona for us,” Jere says. “We didn’t have the veteran pickers in the group. So we supplemented the whole show with good flow, not a bunch of dead spots that leave people just sitting there. We just decided we were going to entertain people.”

Over the course of a Cherryholmes show or album, every member takes a turn singing lead—treating audiences’ ears to a shifting array of vocal ranges, timbres, phrasings and styles of emoting, or as Jere puts it, “clearing the people’s palate off.” Emotional range also governs their song selections. “If you can link up emotional words with emotional tunes then you can really reach inside of somebody,” he says. “When we look at the song list, we purposefully try to take it up and down. We want to engage the audience and have them experience something rather than just listen.”

North Carolina quartet Chatham County Line are colored by a different pair of elements—rock and bluegrass, respectively. The first acoustic music that truly caught frontman Dave Wilson’s ear was Steve Earle’s Train a Comin.’ Wilson also has a rock band called Stillhouse on the side, which served as an incubator for some of the songs that will appear next year on Chatham County Line’s fourth album. “There’s something about playing with a drummer, that rhythm that’s established,” Wilson says. “You can create over top of that a little easier than if the four of us jam acoustically.”

That parallel musical stream lends Wilson, John Teer, Greg Readling and Chandler Holt a loose, devil-may-care feel that goes over well in bluegrass settings and rock clubs alike. “It’s a product of who we are, really, because we’re not into the traditional bluegrass scene as much, we didn’t grow up with it,” Wilson says. “We come from the rock ’n’ roll background, so it seems like a natural extension to be a part of something that will appeal to both of those audiences. I think we’re kind of a gateway drug for bluegrass for some people.”

When Wilson sings and the rest of the band harmonizes, it doesn’t have the penetrating vocal sound of traditional bluegrass—their vocal blend is closer to the hazy, reverb-drenched quality of the Byrds’ Sweetheart of the Rodeo. “I was a product of classic rock,” says Wilson. In fact, he’s prone to describe the band—and its effect on audiences—as that of an acoustic rock band. “I think they see the energy and the passion that we put into the show,” he says.

Besides acoustic instrumentation and varying levels of bluegrass roots, what Bradley, Cherryholmes and Chatham County Line have in common are verve, emotion and a desire to entertain audiences that isn’t at all veiled with irony or aloofness.

Bradley, for one, sees a kinship between bluegrass and other visceral, emotive musical forms past and present. “It’s just the same guts, the same heart and guts. We may be in different bodies but those insides are the same. Bluegrass lays it on the line.”