Rock: Progressive rock? But this is the 90s

They're back. The twin pillars of Seventies prog rock, the progenitors of pomp, parsimony's public enemies, Genesis and Yes, are fresh from producing new albums and are both currently on tour. Thirty years in the business has obviously not dulled their enthusiasm (they surely can't be in it for money), but the new product (some songs dare to come in at under five minutes!) bears little resemblance to the conceptual structures of old.

But surely Genesis are no more following the departure of crafty cockney Phil Collins? A passing acquaintance with the history of prog rock bands reveals that having the same personnel for two albums in a row is something of a luxury. When Peter Gabriel left Genesis in 1975, the music press were quick to write the band's obituaries. At least 23 years too early as it turned out: Collins took over singing duties in addition to drumming and, when guitarist Steve Hackett departed in 1977, bass player Mike Rutherford traded four strings for six. And as for Yes ... keyboard player Rick Wakeman joined the band in 1972, left in 1974, rejoined in 1977, left in 1979, rejoined the then Anderson Bruford Wakeman and Howe (bass player Chris Squire owned the name Yes and blocked their use of it after a split) in 1988, rejoined a reunited Yes in 1991 and had left by 1994. Clear so far?

Perfectly. But what was the secret of their success in the face of these staff upheavals? It certainly wasn't the search for the elusive three- minute pop gem. In 1973, Yes gave the world Tales from Topographic Oceans, a double album featuring four tracks (no, really), with such crisp and cogent lyrics as "Dawn of light lying between a silence and sold sources chased amid fusions of wonder in moments hardly seen forgotten".

Oh, of course. And Genesis? Less turgid, but partial to the odd 20-minute symphonic work (eg "Supper's Ready") and whimsical-cum-classical lyrics. How about "From a dense forest of tall dark pinewoods, Mount Ida rises like an island/ Within a hidden glade, nymphs had kept a child/ Hermaphroditus, son of gods"?

Not a lot about falling in love or losing your job then. Wake up at the back (I know the keyboard solo was 11 minutes long but you've got to concentrate). This is progressive rock, pushing back the frontiers of what's possible musically, not run-of-the-mill pop.

But who would want to listen to that kind of nonsense in the oh-so-ironic Nineties? Apart from its obvious influence on Eighties bands such as Marillion, prog rock has been a big (if largely unacknowledged - it's just too embarrassing) influence on the sound of bands like Radiohead and the "post-rock" noodlers Tortoise ie long "pieces" divided into a number of "movements", each with distinct themes, characterised by quirky time signatures (wave goodbye to 4/4) and unexpected chord progressions.

But just as that type of music gains some sort of currency...

Exactly. Our mainstays of progressive rock try something else. To be fair, they both embraced pop and its `aunty ways some time ago, with some success. Now though, Yes have wafted towards a fey, New Age-adled, tinny pop idiom. Fans will be pleased to note, however, that lead singer Jon Anderson's trademark singing-an-entire-song-on-one-note style still survives. Genesis, on the other hand, with new vocalist Ray Wilson (formerly of Levi's 501 soundtrackers Stiltskin), want to return to a "darker" sound, "to the old melodrama". First results are not encouraging.

Genesis play Manchester tonight; Yes play Hammersmith Apollo on Friday 24 April