By half past nine, all of the pool tables at Bar Leucadian are taken, and fortysomething couples line the bar like birds on a wire. They are exposing an inordinate amount of cleavage and chest hair, and I watch as a man in a suit and gleaming leather shoes orders a drink. He looks around self-consciously at the others, who wear stonewashed jeans two sizes too small.

Most are turned toward the band, playing at the front under a surfing video and a sign that spells out “Illicit Behavior” in alternating colors of Day-Glo paint. Illicit Behavior is now several minutes into a Ted Nugent cover, and each musician — from the drummer pounding out the beat to the lead singer — is intensely focused. Their heads are down as they play, and when they look up, they look at each other, nodding in time to the beat. They don’t seem to mind that the dance floor is empty except for Sergio, a 22-year-old rocker in the heavy metal band Axson. He wears black lace-up leather pants with chains and has long, curly hair, which he shakes wildly while he repeatedly makes the heavy metal hand sign over his head.

Sergio stands in sharp contrast to the members of Illicit Behavior, who are a far cry from the undernourished-looking twentysomethings that usually skulk onstage, belting out angry lyrics. Most of the members of Illicit Behavior have receding hairlines and deeply lined faces. They wear baggy jeans and T-shirts. And they are each old enough to be Sergio’s father.

A man with white hair, shorts, and flip-flops tries to get the women at our table to dance, but the six of us shake our heads. “It’s usually a lot more wild than this,” says my friend Sarah, a neighbor of the lead singer, Marcus Matherly. Last month when Illicit Behavior played, women were flipping up their shirts and trying to jump onstage. Now I watch as several women — lined up hopefully against the wall — play with an inflatable microphone. It’s so large that when a woman holds it up, it hits her knees.

“Hey,” Matherly yells over to them after a Led Zeppelin cover. “Is that the biggest thing you’ve ever had between your legs?”

The musicians I listened to while I was growing up in the ’80s did not have receding hairlines or wrinkles. They had Mohawks and leather jackets. They partied all night, free of worries about how their children were doing in school — probably because they didn’t have kids. Most didn’t even have wives. But now it’s not unusual to see middle-aged men and women onstage, playing way past rock-star prime.

Bono is 47. Joe Walsh is 60, and Mick Jagger is 64. They are all still playing, mostly to sold-out crowds. Locally, quite a few bands with baby boomers at the mic play clubs monthly; many more play at weddings and corporate events.

“I know lots of other people doing this too,” says Phil Beaumont, who, at 40, is a former manager of God Machine and a musician and singer in Maquiladora, who have put out six CDs in the last decade.

Tim Mays, owner of the Casbah and widely regarded as the glue of the San Diego music scene, says that he sees older musicians in all kinds of bands, including rock, punk, metal, jazz, rockabilly, and country. “I think anyone out playing music that they love and enjoy playing is great — old or young. There are bands like X, TSOL, Adolescents, and others, who are all punk rock bands from the early ’80s that are still out playing, enjoying themselves, and drawing decent crowds.”

I ask Matherly, Illicit Behavior’s lead singer, why he still plays. “Hey, it’s not like I’m an athlete and past 35 I can’t play ’cause my body hurts too much,” he says. “With music, you’re never done. You can play till you’re 80. In fact, I sing better than I did in college. If you’re good at it and you love it, why not?”

John Adams, who plays guitar and keyboards in Illicit Behavior, says, “I’m 52 going on 18.” He’s been playing music since he was 5, and in addition to playing in Illicit Behavior, he works at Band Central Station, a music store in Vista he’s been involved with for the last 15 years and owned for 4. “I don’t see me quitting playing,” he says. “It’s just what I do. The music store makes my living, but it’s just something to see me between gigs.”

Matherly — who looks years younger than his actual age, 44 — believes that older people play in bands longer because it’s socially acceptable now in a way that it wasn’t 30 years ago. “In the ’70s, ’80s, and even the ’90s, rock and roll was about youth and anger. If you were 40, you were considered over the hill. Now there’s a resurgence of older rock bands — Yes, Genesis, the Police, Aerosmith — and all those guys are in their 60s.”

Another big change is in the music itself. John Adams explains his own musical version of evolution theory to me: musicians who played rock and roll in the ’50s and ’60s couldn’t keep up with the changing times and dropped out. “The sounds changed,” he tells me. “The amps got louder, the songs got more difficult than the three-chord that came out of the ’50s. Music evolved.”

Myhearpod.com, a company specializing in hearing aids for baby boomers, states on its website, “Baby boomers are the first generation to be exposed to electronically amplified sound. Perhaps a defining image of youth for this generation is that of booming drums and squealing electronic guitars played by rock bands like the Grateful Dead.”

A common denominator among many baby boomers playing rock and roll is that they grew up playing music in their homes. John Adams started piano at age 5, played drums in the school band when he was 9, and got into guitar when he was 13. Matherly’s parents were flower children in the ’60s, and he was introduced to Jimi Hendrix at a young age. “I was always around music,” he tells me. “My dad played guitar and had a great voice, and by the time I was 10, I discovered I had a voice and a gift in terms of being able to sing.”

Hank Morton played guitar and keyboards for four years in the indie band Ilya, which has put out several CDs and was nominated for awards at the 2002 and 2003 San Diego Music Awards, including Best New Artist, Best Alternative Album, and Album of the Year for Poise Is the Greater Architect. Morton also grew up with music, and he tells me stories about jamming with his brother and dad. As he talks, Morton runs his hands through his short blond hair, so that after a few minutes, it sticks up in tufts, much like his infant son’s. It is only after our conversation that I notice the bald spot on the top of his head.

Paul Clark, who plays guitar in the classic rock band Meknes, is modest about his musical accomplishments. A native San Diegan, he speaks with the slow drawl of a surfer, but he becomes animated as he tells me about his first guitar. His parents brought it back from a trip to Tijuana when he was 7 and told him he could take lessons. In 1970, when Clark was 13 and had a paper route, he saved up $300 and bought a one-year-old Martin guitar. “It’s worth $3000 now,” he says, and in the next breath, he mentions that recently he found out that his father used to play jazz on the Santa Cruz pier. “He played every Friday night and sometimes on the radio, until he ran away to join the Navy and his mom sold his sax.”

Richard Fish, a 48-year-old ophthalmologist who plays in the classic rock band Double Vision, can’t remember a time when he didn’t love to play. “I remember as a small kid holding make-believe guitars, pretending to play along with Beatles records with my brother and cousins. Some of us took up an instrument, drums and guitar in my case, started playing a bit, then found other kids to play in a band with. As you get older, if you keep up with it, I guess there is some sense of wanting to go back a bit in time, playing the songs you grew up with and loved.”

“The appeal for getting into music is universal,” says Hank Morton. “You have a message or you want to create something beautiful. It’s a universal thing, and it spans the generations.” To Morton, band culture crosses all barriers, including age, gender, and genre.

Another appeal, apparently, is the chicks. “Even as a happily married guy, it’s fun getting attention from girls,” Matherly tells me. “It’s fun flirting. One thing with older musicians, you could have been the ugly duckling — you could still be the ugly duckling, and you’re skinny and wrinkled — but you’re the man. Girls who would never give you attention outside of a club are throwing themselves at you when you’re onstage.”

Fish of Double Vision tells me by email that his wife doesn’t mind women throwing themselves at her husband. In fact, according to Fish, she still finds drummers irresistible, 22 years after she first saw him play. He adds, “I think that men are just grown-up boys. And to some degree, boys will be boys. Some guys hang at the bar with buddies, some are avid golfers or bowlers, and some are members of service organizations. And some of us are just playing in rock-and-roll bands.”

And yet, all of these reasons don’t explain why these men are onstage. After all, it’s not easy to be in a band while holding a day job and raising kids.

“The hardest part is that I feel guilty when I practice,” Matherly tells me. Illicit Behavior practices from nine until midnight every Tuesday night. On weekends that the band plays, Matherly has to get ready at about four, drop off the equipment, set it up, and then play. On nights his band has gigs, he’s lucky to come home by 3:00 a.m. “The next day, my six-year-old son wants me to get up with him, and I’m exhausted all weekend.”

Hank Morton, who’s in his 30s, left Ilya because the touring became a strain after he got married and bought a fixer-upper house. “I burned out on it. All of a sudden, new stuff was dominating my life — I was building a business, I bought a house, and then my son Seth came along.” Since then, Morton has had another son, Spencer, now six months old.

Phil Beaumont of Maquiladora is the director of the Museum School, where he also teaches. “Our school has been trying to move into the new Children’s Museum,” he says when we talk in September. “I haven’t played a lot this year, and it’s been a heavy weight on my shoulders. For me, just the way our band is set up, and working as a teacher, it’s a matter of when we can tour. It requires planning and flexibility.” On November 30, the board of directors at the Children’s Museum decided that the museum would no longer house the school. Now Beaumont must search for a new facility as well as host “a number of fund-raising events.”

So what keeps these guys practicing, memorizing lyrics, and getting up onstage? It’s not the money — everyone I spoke to said he was lucky to break even playing at bars.

I am reminded of what Joseph Campbell, renowned mythology professor, once referred to as “peak experience” and of what Dr. Mihaly Csíkszentmihályi, psychology professor at Claremont Graduate University, calls the “flow state.” In his book Flow: The Psychology of Optimal Experience, Csíkszentmihályi describes “flow” as “being completely involved in an activity for its own sake. The ego falls away. Time flies…your whole being is involved, and you’re using your skills to the utmost.”

Matherly says he wouldn’t feel complete unless he was singing. “As a musician, there is nothing more. There is not a greater high than getting up onstage and commanding the crowd. It’s a sense of power. It’s an amazing thing, like surfing a really large wave, but it’s continuous.”

“I miss it when I don’t do it,” says Beaumont, of Maquiladora. “There’s those moments playing when your eyes close and it feels really good. For those moments it’s worth it. When I take the time to play, even an hour or so, I kind of win it back, you know?”

Paul Clark describes the first time Meknes played at the Serra Mesa street fair. “I was walking on air for three days afterwards,” he says and then pauses. “Part of it is, I remember when I was younger playing, and I would force myself to play, and it was all about getting the chicks. But we’re all established now and have pretty good love lives, and that’s not part of it anymore. It’s kind of distilled down to the music and the camaraderie of the band. It’s nice not having to impress people for personal gain — it’s just a creative outlet.”

Maybe older musicians have an even easier time of achieving the flow state because they have nothing more to prove — they are in it for the joy of playing.

“Once a band has been around for a certain amount of time,” Tim Mays says, “they may come to realize that they’re not going to be huge and make a ton of money, and at that point, they decide to go back to playing music for the reason they first started — fun.”

Morton tells me, “Music was always something I wanted to do with my life. I wanted to play with a neat group of people and create something that was lasting. In a lot of ways, we did that. The neat thing was to do something we were proud of, the act of recording an album and CDs that are still out there.”

When I ask Morton if he’ll go back to playing when his children are older, he hesitates. “I don’t know,” he says. “It wasn’t anything great, but I’ll always be able to have it. Seth might someday go through my things and see my CDs. It’s the lasting power of art,” he says. “It’s what surpasses you.”

“I’ve seen friends just stop playing, and I’ve seen friends that have kept on going,” says Beaumont. “If it’s something that feeds you, you keep going. That’s why you get into music in the first place. ’Cause you dig it.”