The Rolling Stones used to say there was no reason for them to stop performing because their idols, like Muddy Waters, didn't stop when they got old. But Muddy Waters in his late sixties looked like a full-grown man. Mick Jagger looks like a kid in his twenties with the head of a full-grown man surgically attached. (And don't rule this possibility out.) If The Rolling Stones tour more this year (which is likely), they'll have outlasted Muddy, who died at 70, the age Mick Jagger will turn on July 26.

One of the weirdest things in rock 'n' roll right now is that guys in their sixties and seventies are having a hell of a year. No one planned for this: Leonard Cohen, at 78, is filling arenas for three hour shows, and making records better than the ones he released in the 1960's. Bob Dylan is, at 71, rediscovering -- yet again! -- the spark of his genius in live performance, this time out as a mephistophelian hep-cat telling dead-eyed stories and deadpan jokes about a world gone wrong. On his 66th birthday, David Bowie proved capable of holding the attention of the world media with the surprise release of four minutes and nine seconds of quiet music.

And there's Mick Jagger, at 69, engaging in onstage aerobic activities that would tax the knees of man half his age. It's hard to know what to make of it all.

Jokes come easy, and have for a long time. Fifteen years ago I edited a dismissal of the Stones' Bridges To Babylon that contained the advice, "The prune juice is in aisle 5, Mr. Jagger." And the tweet I didn't send as I climbed up to the balcony of the Barclays Center in Brooklyn to see the Stones play in December, during their brief 50th anniversary tour? "Number of canes spotted on way to my seats at Barclays: 2. Number of walkers: 1. Number of Rascals: 1."

Snarky, and maybe telling. Also stupid, mean and misguided. It misses the point entirely: Fifty years ago, at the start,The Rolling Stones represented a sort of freedom almost impossible for most of their audience to achieve, the freedom to live exactly as they wanted. Fifty years later, they still do, in ways far more poignant and pointed than before.

Granted, it didn't seem very poignant at the time. Just strange. People going nuts more for the opportunity of being there than anything else. Onstage Mick Jagger and Ron Wood were rail thin with dark hair, and Keith Richards and Charlie Watts had gone grey and carried a hint of a human belly above their tight trousers. It was as though Keith and Charlie had decided to be old, while Mick and Ronnie decided to stay 35 forever -- a band evenly split between negotiating with the aging process and defying it.

Maybe that's what made that new David Bowie song so striking. With its lyrics about walking the dead and its static, decidedly unglamorous video, "Where Are We Now?" isn't about defying age or weathering it, the way the Stones or Leonard Cohen can be. It reaches back to Bowie's youth, when he was lost in Berlin at age 30, but without nostalgia. It's less about mortality than dissociation.

Growing old in rock 'n' roll is uncharted territory. One of the oddest things about all this is how many of these guys seemed completely lost in their forties (I dare you to listen to Knocked Out Loaded, released one week after Bob Dylan's 45th birthday), and seem to have figured it out now, just when you think they'd be hanging it up.

What do you think? Is there such a thing as too old to rock? Weigh in below! You can also email us at soundcheck@wnyc.org or leave a voicemail: (866) 939-1612.