If you want a glimpse of Comic-Con past — before the San Diego convention became the swollen, studio-driven, 125,000-attendee hub of the pop-culture universe that it is today — drop by L.A.’s Shrine Auditorium, where comicbook aficionados gather monthly as God probably intended them to, without much interest or interference from the outside world.

That’s pretty much what Comic-Con, preparing for its 39th annual edition, still was in the mid-1970s, when my older brother and I made the trek down the freeway from Los Angeles — almost invariably in a little more than two hours, by the way, with minimal traffic — to feed our joint comicbook collecting fetish.

Back then Comic-Con was truly about comicbooks and the only stars one was likely to see there were the artists and writers who created them. The confab itself was so strapped for cash that each year the artists donated work — which they dutifully sketched out on easels as a small crowd watched — that were auctioned to help support the gathering.

In those early days, the entire convention of a couple thousand people could be held in a single hotel. One large ballroom functioned as a dealers’ room, where vendors displayed their wares, and an adjacent space housed panel discussions. Gradually, studios began to preview movies there, but as often as not those events were disasters, irritating fans as opposed to whetting their appetites.

Although it was more than 30 years ago, for example, I keenly recall a preview of the 1978 feature “Superman,” where the studio rep described the campy villain Lex Luthor, played by Gene Hackman, as a real-estate mogul, not a master criminal. He was practically hooted off the stage.

Gradually, the studios started to wise up, hiring publicists specifically trained to handle Comic-Con’s savvy but easily riled audience. When Ridley Scott’s space-horror film “Alien” was showcased — using little more than a slide show of surrealist H.R. Giger’s jaw-dropping conceptual art — the crowd was blown away.

The gathering was small enough back then that most attendees who cared to could participate in the few available nighttime activities, from the Masquerade ball (a costume contest for those with way too much time on their hands) to latenight movie screenings.

The featured movies tended to hew toward obscure fantasy and adult fare, from the R-rated sci-fi spoof “Flesh Gordon” to “Beyond the Valley of the Dolls,” a Russ Meyer exploitation flick filled with nudity, music and unexpected violence — written by some guy named Roger Ebert. Plumes of marijuana smoke were so pervasive within the room that organizers briefly stopped the film, warning that the police were threatening to shut down the convention.

The watershed moment for Comic-Con doubtless came with the release of “Star Wars” in 1977, though it took a while for the wholesale mainstreaming of sci-fi and fantasy to begin in earnest. Lucasfilm soon zeroed in on the Con’s promotional value, sending those assembled into spasms of glee simply by premiering “The Empire Strikes Back” trailer there. Relatively soon, attendees began to expect such exclusive treats, and the event grew by Kryptonian-style leaps and bounds.

Returning to Comic-Con years later, it was clear the studios had mastered geek-speak, and the convention had exploded into something that reaches far beyond its roots into movies, TV, gaming — anything within the pop-culture lexicon. Indeed, the very name has become a misnomer, inasmuch as one is as apt to run into talent agents as comic collectors at the various nighttime shindigs.

Then again, one is also likely to run into huge traffic jams somewhere around Carlsbad, 30-minute waits for a pretzel, and lines for the cavernous 6,500-seat main auditorium that snake halfway around the convention center. And that’s not including the B.O. (and no, that doesn’t mean box office) that can permeate the enclosed spaces when enough grown men in Klingon and Hobbit suits amass on a filled-to-capacity summer day.

Consider it a reminder that while growth and change are perhaps inevitable, the two don’t always signal progress.