Column: Remember when Letterman was the epitome of edginess?

In a final passing of the torch to a new generation of late-night talk show hosts, David Letterman announced last week that he would retire in 2015. As intelligent and unique a force as he’s always been, the timing seems right.

Since beginning his late-night career more than 30 years ago, Letterman has evolved from exuberant, smart-alecky nerd to crotchety, occasionally befuddled elder statesman. Watching him now, it’s hard to believe he was once considered the epitome of edginess, a darling of the college crowd and hero to sarcastic eggheads everywhere. It’s hard to believe that dropping watermelons from a five-story tower or attaching yourself to a wall with a Velcro suit was once the perfect marriage of adolescent goofballery and ironic detachment.

But when “Late Night” premiered in 1982, irony had not yet become the default mode of the culture. It was Letterman, along with institutions like Spy magazine and “Seinfeld,” that would take it out of the “alternative” mien and push it squarely into the mainstream. In time, the sardonic, deadpan sensibility that once felt revolutionary was in play everywhere from ads to pop music to politics.

When Walter Mondale asked, “Where’s the beef?” during the 1984 Democratic presidential primary, referring to an iconic (and prototypically ironic) Wendy’s commercial, he was tapping directly into the Letterman ethos.

Since then, that ethos has been watered down into banality. The novelty of “stupid human tricks” and “stupid pet tricks” gave way to reality television. Letterman’s signature Top 10 morphed into the photo slide shows and Buzzfeed lists that now dominate the Web.

But it’s not only the mainstreaming of irony that’s made so much of Letterman’s shtick so irrelevant, it’s the mainstreaming — the glorification, even — of nerd culture. In his heyday, Letterman was nothing if not a testament to the ways in which wit and humor could triumph over stiffness and introversion. Moreover, his refusal to fawn over celebrity guests signaled that he wasn’t just any nerd but a nerd who could not be corrupted by popularity. Instead of using his celebrity to date starlets, he treated them a little cruelly on his show. Which just kept them coming back for more.

The nerdscape of today, however, operates with a different form of currency. The digital revolution has anointed geek geniuses as masters of the universe. The socially awkward don’t need wit and humor to get by anymore. They need an IPO — or maybe just the possibility of one. Money doesn’t just make cool. It makes cool unnecessary.

It’s notable (I won’t say ironic) that Letterman announced his retirement the same week that HBO premiered “Silicon Valley,” its comedy about tech moguls with gargantuan wealth but no people skills. The characters are right-brained in the extreme: They have no idea how to dress, how to spend their money or how to act around women. Yet, thanks to an economy that can catapult someone from the science fair to billionaire status with few stops in between, they are also bombastic and ballooning with self-regard.

And they are notably lacking in the compensating quality that nerds have long relied on: humor. “Silicon Valley” is funny precisely because the characters are not (at least not intentionally). And the reason they’re not is that the very rich, like the very beautiful, don’t need to be funny. Humor is rooted in humility. That’s why it’s largely been the domain of those who tend not to find themselves on the top of the heap.

Now the top of the heap is occupied by with people who, 30 years ago, would have sneered at the whole notion of the heap. They would have watched David Letterman and worshipped at the altar of his beguiling, if always faintly menacing, dorkiness. Moreover, they would absorb the lesson that always existed just beneath the surface of Letterman’s act: It’s possible to feel superior and inferior at the same time; in fact, you can’t have one without the other.

When Letterman leaves, we’ll not only be saying goodbye to the last of his generation but one of the last of his kind: the smart guy for whom stupid human tricks were fundamentally a celebration of humanity. In “Silicon Valley,” the smart guys just think most other humans are stupid, period.

It kind of makes you want to drop a watermelon off a tower.

mdaum@latimescolumnists.com Twitter: @meghan_daum