Scene 1: It is the spring of 2017, and I am teaching a class of high-school juniors. I do an icebreaker in which I ask each student one of a half-dozen different questions, and one of them is “name a band or performer you like.” The kids do not name a single artist I’ve heard of, nor do any two people mention the same artist. They aren’t listening to the top of the Top 40, or they’d mention Ed Sheeran, the Chainsmokers, the Weeknd, Bruno Mars, Drake, or Rihanna. I wonder if they’re sharing a generational musical experience at all, or if they’re part of small circles that rarely overlap other circles.

Scene 2: It is the spring of 1977, and I am a high-school junior. I live every non-school moment with the radio in my ear, where the top of the Top 40 sizzles with springtime energy, including Thelma Houston’s “Don’t Leave Me This Way,” Glen Campbell’s “Southern Nights,” “The Things We Do for Love” by 10cc, “Dancing Queen,” and “Rich Girl.”

Scene 3: Back in 2017, I am in the car, listening to an oldies station on AM. It’s a gorgeous afternoon, sunny and warm, and the car is powered as much by the radio as it is by gasoline. “Summer in the City,” Lou Christie’s “Lightning Strikes,” “I Hear a Symphony,” War’s “Low Rider,” and on and on, every one memorable, every one uptempo, every one by itself enough to make one grateful to be part of the generation that created it.

It is hard for me to imagine that 40 years from now, after I’m long dead and my students are the age I am today, that they will feel the same kind of generational solidarity with the music of the 00s and 10s that I feel when I listen to the music of the 60s and 70s. It’s not just that they don’t listen to the kind of mass-appeal radio stations we had back then. It’s got something to do with the music itself.

In his book 1965: The Most Revolutionary Year in Music, Andrew Grant Jackson cites a 2012 academic study that examined the tempo and key of more than 1,000 hit songs released between 1965 and 2009. Researchers determined that in the 1960s, 85 percent of pop songs were in a major key, but during the 00s, only 42.5 percent were. Hits of the 60s averaged 116 beats per minute and ran about three minutes; hits of the 00s averaged around 100 BPM and ran about four minutes. Jackson writes, “Our culture perceives songs in major keys with fast tempo as happy and uplifting, whereas slow, minor-key songs are interpreted as sad, serious, complex, and sophisticated.” The bottom line is that today’s music is slower and sadder than music used to be. Skating the thin line between pleasure and pain by listening to sad songs has been a part of the pop-music experience for nearly 70 years now. But in recent years, as you trace the historical curve of that line, it seems like pain has become almost the norm.

The stereotype of an oldies radio listener is of an old person trying to recapture his or her youth. There’s something to that. A song like “Low Rider” comes with a set of associations that I enjoy remembering. But there’s certainly more to it than just simple nostalgia. Many people who aren’t old enough to remember when “Summer in the City” was a hit enjoy it, and there’s data to prove it: it’s my limited understanding that when radio stations do music research with listeners, 90s music tends to do poorly compared to stuff from the 80s [late edit: and other decades, too–Ed.]. The continuing popularity of 70s music with people of all ages is easy to see even without research data. And maybe all of it has something to do with the historical curve of that line.

Will oldies stations of the 50s—the 2050s—play the hits of the 90s, 00s, and 10s the way oldies stations today play the hits of the 60s, 70s, and 80s? I suspect not. And if they don’t, the reason may be a simple one: Who wants to feel serious and sad all the time? Or even 42.5 percent of the time?