Image: CBS.com

My daughter started watching The Big Bang Theory with my wife and me last fall, and she got hooked pretty quickly.

The show took far longer to reel me in, frankly, because when TBBT kicked off in fall 2007, it seemed much more about poking fun at geeks rather than skewing its humor toward geeks.

That pendulum has swung significantly in the opposite direction over seasons two and three, though, so I recently brought home the season one DVDs from the library to see if the early adventures of Leonard Hofstadter, Sheldon Cooper and their neighbor Penny were as bad as I remembered. They’re not, really, although I’m obviously watching them now through a fan’s eyes. Still, they make it easy to see just how much the show has evolved.

Consider some of the early gags, like Leonard emerging from his bedroom armed with a Force FX Lightsaber to investigate a middle-of-the-night noise.

Though I appreciate the shout out as a Star Wars fan, it’s really an all-too-easy joke, and besides, as everybody knows, those things are expensive and breakable.

That same oft-mined-nerd-joke-territory feeling comes up all through the early episodes: The guys and their friends Howard Wolowitz and Rajesh Koothrappali play Klingon Boggle; they only talk to women on MySpace; they visit Penny’s ex-boyfriend and get sent home de-pantsed. It all struck me as rehashed Revenge of the Nerds stuff, and that was already well-worn in the 1980s.

Now, contrast that with what we see in seasons two and three, and it’s clear TBBT has totally aimed itself at a geek audience rather than making the easy jokes at their expense.

Check the guest stars: Summer Glau. Wil Wheaton. Nobel Prize-winning astrophysicist George Smoot. Katee Sackhoff. Danica McKellar.

And the offhand references and minor plot points have also become much more geek-Easter-eggy, with nods to everything from Edwin Abbott Abbott’s Flatland to a Pictionary representation of the phrase “Higgs boson particle” to a bet with The Flash #23 and Fantastic Four #48 at stake.

Penny’s at the epicenter of the other pretty seismic shift in TBBT’s tone. Even my daughter noticed right away while watching the DVDs that through the first four or five episodes of the series, it was seemingly not enough that Kaley Cuoco’s bubbly blonde wasn’t a geek. She was portrayed as an airheaded idiot who talked in a squeaky Valley Girl voice. (I’m not the only one to notice this change, either.)

Fortunately, that persona  - and, thankfully, that voice - disappeared pretty abruptly beginning with an episode in which she joins the guys for Halo 3 and utterly pwns Sheldon. This marked the beginning of her growth as a character and really makes a huge difference in the show’s chemistry.

Oh, and Bonus Points because TBBT has UCLA particle physicist David Saltzberg on board as a science consultant. He takes care of things like making sure appropriately complex-appearing equations show up in the background, and he writes a little about some of the science in each episode at his own The Big Blog Theory.

Yes, the easy jokes still come around from time to time. And being a sitcom, TBBT is still prone to circumstantial exaggerations that stretch credibility. And yes, its writers will take a hit or two in some quarters for perpetuating stereotypes of brilliant social misfits.

But you know what? It’s clear now that they get us.