There’s still hope. In pictures from this year’s Lollapalooza, in August in Chicago, Jane’s Addiction singer Perry Farrell and guitarist Dave Navarro were, as required by rock-guy law, throwing various rock star poses at the crowd.

They looked like a couple 25-year-olds who just walked off the beach with their surfboards. Both were sweaty. Both were shirtless and had plenty of hair. Neither had an ounce of fat on them. Navarro is 42. Farrell is 50.

Next up were pictures from the same Lollapalooza, this time of Depeche Mode. You remember them. Dramatic British guys, funny hair, big at the start of MTV. When they did Jimmy Kimmel’s show in April, they had to shut down Hollywood Boulevard to accommodate all the fans. They headlined Lollapalooza. Singer Dave Gahan is 47.

Three out of four members of Sonic Youth, still considered the defining art rock/noise band for millions of music snobs, and cool enough to appear this fall on the teen soap drama “Gossip Girl,” are in their 50s. Bassist Kim Gordon is 56 — old enough to be my mother. Kind of.

Most members of Wilco and Radiohead — both still churning out some of the best serious rock music in the world — are in their 40s. It’s hard to believe, but it won’t be long until the guys in Green Day join bands like the Red Hot Chili Peppers, Metallica and Tool in their 40s.

The road between musical generations seems to go both ways, as anyone who’s been to a Clay Aiken show and almost been trampled by hyped-up grandmothers could tell you. While kids are listening to middle-aged rockers, middle-aged people are apparently listening to kids.

Younger acts still rule the pop charts, thanks to teens having nothing better to do with their disposable income than to buy and/or download artists shoved down their throats by cable TV. But when it comes to what’s still big in rock music, especially on the live stage, middle-age is in.

There are plenty of reasons. Few new rock artists with long-term star potential have broken out the past decade. Record companies don’t have the budgets to be patient with young, developing bands — which means young bands signed to record deals have to be more concerned with hits than developing artistically.

There’s also the 40-is-the-new- 25 syndrome. So many people in their 40s and 50s grew up with parents who loved rock music, and still do. The musical wall that kids in the 1960s and 70s erected between them and their parents isn’t as cut-and-dried anymore.

A Pew Research Center study earlier this year showed people of various generations tended to like a lot of the same music. The Beatles, The Eagles, Johnny Cash, Michael Jackson (who, at 50, would have set insane attendance records with his planned tour if he didn’t die), The Rolling Stones and Elvis all scored high. Hip-hop is another story, although Jay-Z is 40 and still a major player. Same for R&B stars like Mariah Carey, 40, and Mary J. Blige, 38, who still sell.

But rockers of all ages seem to agree that the old stuff is the best stuff. Almost all the middle-aged bands that are successful started when they were in their 20s. By now, they’re brand names, one reason it’s difficult to make it in the music business if you start after 30. People are willing to take middle-aged rockers seriously as long as they have a long history with them.

Lollapalooza wasn’t an aberration. The big Bonnaroo festival had loads of acts in their 40s and 50s. And the Outside Lands Festival in Golden Gate Park features headlining 40-somethings Pearl Jam and the Dave Matthews Band (the other headliner, the 40-something Beastie Boys, had to cancel because of illness). Tom Jones, who turns 70 next year, is on the bill. Regardless whether his popularity is twinged with irony for many, Jones puts on a great show.

Rock ’n’ roll probably didn’t change the world like our parents thought it might. But it seems, at the very least, to have closed part of the Generation Gap.