Even for those of us devoted to the vital work of picking out movements in popular music, some developments are harder to explain than others. What was nu-rave all about, for example? Who's best, David Lee Roth or Sammy Hagar? And why are people still buying Radiohead records? While the first two can now be answered more or less definitively (bored students and Sammy Hagar, respectively), to answer the third, merely listening to music just isn't enough. We have to look deeper, see the big picture, examine things on a weather-pattern or planetary-trajectory scale and apply scientific principles. What we then come up with are called theories of rock'n'roll.
There is no shortage of these theories, and they are formulated and abandoned continually. Here, we'll deal with just a representative sample, beginning with the broadest, the Golden Age Theory. This has its roots in Greco-Roman times, and posits that culture reaches a peak (usually fairly fast), then dips into a Silver Age before spreading into a long, slow decline. For rock and pop music, the golden age would run from the arrival of Elvis Presley in 1956 to the Beatles' Sgt Pepper's Lonely Hearts Club Band in 1967, and the Silver would be the psychedelic rock era of 1967 to the Sex Pistols in 1976 - what those of a melodramatic bent like to call the death of rock.
This theory is very tidy: the Golden Age encapsulates the years when this music sounded at its freshest, including the excitement of Elvis and rock'n'roll, the joyousness of the early Beatles and Rolling Stones and the glory years of Motown, and emphasising the classical view of rock'n'roll as somehow fatally corrupted by the intellectual influence of Bob Dylan around the mid-1960s. It also hints at how incredibly complicated things became in the 1970s, as soon as rock'n'roll had had enough time to think about what it was doing - Roxy Music spring to mind, with their combination of Little Richard's preening and pounding and so much avant-garde noise - and to start looking back.
It's tidy, but also rather cynical - an unfortunate side effect of the distance required for this project. Worse in this regard is the Theory of Revolution and Decay. Here, the rock'n'roll of the late, great Bo Diddley, Chuck Berry and company is diluted by white boys, first Elvis and then Pat Boone and Cliff Richard, or the melding of folk, country and rock by Bob Dylan and the Byrds in the late 1960s turns into the banal, self-obsessed soft-rock of early Seventies James Taylor and Crosby, Stills & Nash, and so on. It's based on the romantic (but usually correct) premise that selfless artistic endeavour is tainted by commerce and ego, and it works every time, whether it's the idiot savant abrasion of the Sex Pistols leading to the calculated smoothness of the Police or the politically engaged fire and brimstone of Public Enemy being reduced to the brute gangsta bravado of 50 Cent.
It works because, presumably, it's true. So too does the Theory of Action and Reaction, one particularly suited to scientific minds. In the early Nineties, the domination of all-American grunge in the UK clearly provoked the era of Britpop in the shape of Oasis, Blur and Pulp, just as the rise of politicised pomp-rock promulgated by Bruce Springsteen, U2, Sting and Simple Minds in the late Eighties was a reaction to the giddy hedonistic pop of Duran Duran, Culture Club and A Flock of Seagulls in the early part of the decade. You might even say (hell, I will say) that the current favour for folk influences in alternative music is down to the commercial domination of Pop Idol and "manufactured" pop, as musicians and listeners grasp for something they find more meaningful.
Beneath these surface shifts, though, swirl stranger, more obscure patterns that are harder to read. For example, there's what we'll call the Double Decade Theory, where music repeats itself every 20 years. Thus punk replays rock'n'roll, Eighties new wave is revived by Franz Ferdinand and the Arctic Monkeys in the 2000s, Oasis borrow from the early-1970s pop of Slade (probably more accurate than their efforts to align themselves with the Beatles) and the Eighties hair metal of Guns N' Roses and Poison is a reworking of Hendrix and Black Sabbath in the late 1960s.
Though no Origin of Species, this works pretty consistently, particularly when allied with the more individual Golden Years Theory, which suggests that bands are influenced by the music being made just before they were born. Whatever the reason for this (possibly because musicians always want to be seen to know more than their peers), since most bands begin in their late teens, this also tends to result in cycles of around 20 years.
Getting more arcane, there's the Theory of Seven, one for people who read horoscopes. This places all the most significant moments, or seismic shifts, in the evolution of music in the seventh year of the decade. For 1957 it was rock'n'roll, 1967's was Sgt Pepper's and the Summer of Love, 1977 had punk (or new wave, if you're a purist), 1987 gave us acid house's "Second Summer of Love" and the rise of hip-hop (Public Enemy and NWA), and 1997 was… well, where it sort of stopped working. Even for the UK, Britpop was dead and gone and we can only hope that that the release of Radiohead's OK Computer that year doesn't prove to be an all-time significant event in rock music (though it would help to explain that mystery we mentioned earlier).
That's the trouble: constant ripples, swirls and eddies make it hard to pick out trends close up. The availability of certain drugs always has an influence, and economics also muddy the picture: since the depression of the Thirties, for example, it's been said that escapist pop or dance music thrives in times of hardship. Politics, too, gets involved. The Theory of Seven tends to cross over, whether by coincidence or for good reason, with tides of social upheaval: 1967's psychedelic revolution, for example, coincided with the rumblings of a rather more physical one, as manifested in 1968 by students on the streets in Paris and in the US by anti-Vietnam protest. It might even be that 1997's seismic shift turns out to be the election of the two "rock 'n' roll premiers", Bill Clinton and Tony Blair, in the traditional homes of rock and pop. Let's just hope we missed something big last year, because 2007's is looking very much like the arrival of the download album, courtesy of our old pals Radiohead.
James Medd writes for The Guardian, The Independent and Esquire magazine.
