But what about in their 60s, 50s, or even 40s? Think of classical or jazz composers, painters, novelists, playwrights, poets — those who work in these art forms don’t typically peak in their 20s or 30s only to fade out over the remaining decades. Yet that is the nearly invariable pattern in rock music.

In this respect, at least, rock ‘n’ roll has proven to be exactly what its critics said it was back in the early days of the rock era — music for young people — though in a sense somewhat different than they intended it. Back then, when people (usually parents of rock-obsessed teenagers) said that the new music was for kids, they meant that it was childish, that its highly amplified racket, throbbing rhythms, and disregard for established norms appealed only to young people, who would soon outgrow its excesses. That has obviously been disproven by time, as the teenagers of the 1960s have aged while remaining adoring fans of the Beatles, the Stones, and their many successors, and as the same process has repeated itself across subsequent generations of artists and fans.

Yet the epithet about rock being young-people music has been vindicated in another sense. Once the rock stars themselves age beyond their late teens, 20s, and 30s, their talents nearly always wane and recede in a way that appears to be unique to rock, indicating that its sources are deeply intertwined with the character of the art form itself. How could that be? What is it about rock music that links it so indelibly to youth?