If you want to enumerate all the amazing San Francisco Bay Area rock, fusion, and jam bands that have played a role in the region’s storied musical history, you might want to start your count with Zero.

Okay, that’s a silly pun. But it’s no joke that Zero has earned a spot among the pantheon of notable NorCal ensembles in the four decades since their early-1980s inception in Marin County. Zero celebrated their 40-year legacy with two sold-out shows at The Mystic Theatre in Petaluma on Friday and Saturday nights this past weekend.

Zero recorded their first tracks in 1984, hence the anniversary date for these shows. Guitarist Steve Kimock and drummer Greg Anton are the enduring heart and soul of the band, which for many years also featured Quicksilver Messenger Service alum John Cipollina on guitar and Martin Fierro on saxophone (Sir Douglas Quintet, Quicksilver, several Jerry Garcia projects).

Other members of Zero’s touring and recording lineups over the years have included vocalists Judge Murphy and Donna Jean Godchaux-MacKay (the Grateful Dead), keyboardist Melvin Seals (Jerry Garcia Band), and Kimock’s son John Morgan Kimock on drums. Add them all together, multiply by the number of years since the band was founded, and square that by a factor over 1,300 shows – and that’s how you get to Zero.

In addition to some of the aforementioned members of Zero’s lineup history, several other Grateful Dead connections are worth mentioning. Lyricist Robert Hunter collaborated with Zero on many songs. Kimock gained the attention of Deadheads in the 1980s after Jerry Garcia reportedly called him his "favorite unknown guitarist." Over the years, Kimock played lead guitar for many Grateful Dead-adjacent projects, a lengthy list that includes Keith and Donna Godchaux's Heart of Gold Band, Bob Weir's Kingfish and RatDog, Vince Welnick's Missing Man Formation, Phil Lesh & Friends, Rhythm Devils with Mickey Hart and Bill Kreutzmann, and The Other Ones (which at times had all of the “core four” post-Garcia members of the Dead). The Dead cred looms large with Zero.

“I've seen a lot of bands, and no band can put the whammy on a crowd like Zero.” - Robert Hunter

The lineup for Zero’s 40th anniversary shows at The Mystic included the legendary Pete Sears on bass (Rod Stewart, Jefferson Starship, Mooonalice, and a million other recordings and tours), Lowell “Banana” Levinger on guitar (The Youngbloods), Hadi El Sadoon on trumpet, Spencer Burrows on keys, and a promise of some “special surprise guests.”

A portion of the proceeds from these shows will benefit the Camp Winnarainbow Grace & Joy Scholarship Fund. Founded by Mr. & Mrs. Wavy Gravy, Camp Winnarainbow is a joyful and magical sleep away camp where kids from all backgrounds develop community, self-confidence, and artistry through circus and performing arts. The Grace & Joy scholarship fund provides an opportunity for economically challenged kids to attend Camp. Visit www.campwinnarainbow.org for more info.

The Friday night show began with a presentation of a new guitar to Kimock by Grateful Guitars, a nonprofit that provides guitars and other instruments for talented marquee and upcoming musicians in the jam universe. Andy Logan of Grateful Guitars and luthier Bill Asher were on stage to hand Kimock a bespoke “Wolf 2.0” – an exact replica of Jerry Garcia’s “Wolf,” one of several guitars Doug Irwin made especially for Garcia. Asher recently crafted a handful of these masterful replicas using Irwin's original templates and drawings using wood from Irwin's private 30-year-old stash of figured maple.

Kimock played his new guitar for most of the evening, and he seemed to thoroughly enjoy his new axe. The first set began with two instrumental Zero classics, a segue of “Coles Law” into “Tangled Hangers.” During “Hangers,” Kimock and Sears hit stride as they played simultaneous leads. I’m not sure I’ve ever seen Sears throw down such a sweet solo, showing off his jazz chops with well-seasoned veteran virtuosity.

Anton took to the mic to introduce “End of the World Blues” from Zero’s 1994 album Chance in a Million. First, he thanked the crowd for “sticking with us for forty years.” Then, after noting the song they were about to play was written by Hunter, Anton dedicated the song: “About a year ago, Phil Lesh told us this was his favorite Zero song. So this one’s for Phil.” Burrows belted out the blues vocals originally sung by Murphy (who died in 2013) with an appropriate level of reverence and passion. “Rigor Mortis” followed, giving Kimock a chance to demonstrate his slide guitar skills. Then the first set closed with Dylan’s “Highway 61 Revisited,” the first cover song of the evening.

To begin the second set, Wavy Gravy took center stage. He began with his familiar signature line: “You’ve got Gravy in your ear. Perhaps, a Q-Tip?” Then, with the band improvising softly behind him, he recited poetry. Setlist.com says the poem was named “Ocean of Love,” so let’s go with that. Renowned Berkeley clown and self-described “sacred mischief maker” Moshe Cohen accompanied Wavy on stage, holding a large flower prop and adding some comic, poignant visuals – plus some confetti.

The second set was largely covers, including Aretha Franklin’s “Baby, Baby,” a moody instrumental version of Jimmy Cliff’s “Many Rivers to Cross” (with Kimock on lap steel guitar), and “Papa Was a Rollin' Stone.” The latter was made famous by The Temptations but originally written by legendary Motown songwriters Norman Whitfield and Barrett Strong, and first recorded by The Undiscovered Truth. Zero gave their own flavor to the classic hit.

In the midst of those covers, vocalist Stephanie Salva (who sings with Anton in a North Bay American roots band Tumbleweed Soul) joined Zero to sing renditions of two originals. First, Salva belted out full-throated blues on “Pits of Thunder,” and then she bared her soul on “Catalina.”

Throughout the night, Burrows, Banana, and El Sadoon took spotlights to solo on their instruments. Burrows was a good match for Kimock stylistically. Echoes of The Youngbloods were evident in Banana’s accompaniment and solos on keys and mando-guitar. Make no mistake though: since the days of Cipollina and Fiero, Kimock has clearly held ground as the primary soloist and distinctive voice of Zero’s music. When he soars, Zero soars.

For an encore, Zero returned to play “Gregg’s Eggs,” first recorded by Zero for Kimock’s 1989 release Nothin’ Goes Here. “Eggs” is instrumental jazzy rock, which many fans feel is the band’s strongest forte. A compelling, driving beat by Anton propels “Eggs” behind fusion trumpet and guitar solos on a tour through multiple layers that revolve around a catchy musical phrase. A perfect ending for Night One at The Mystic.

No matter how you compute it, you can’t go wrong if the answer is Zero.