Are rock stars allowed to get old?

This year, three of the biggest names in music - Michael Jackson, Madonna and Prince - hit 50. They've each sold millions of records in long careers. But what do their futures hold - and what is the point of a middle-aged pop star?

Ageing performers whose records are ignored and whose concerts no longer sell out often grumble that the music they are recording today is just as good as it ever was. This is not true: rock stars never do work in their 30s that approaches the quality and originality of the work of their teens and 20s. Fame brings too many distractions, even the mildest affluence is the implacable enemy of creativity, and, most important, musical styles change and musicians can rarely change with them.

None of the rules governing ageing rock stars apply to Jackson, Madonna and Prince, just as none of them apply to Mick Jagger or Aretha Franklin. These performers are like the Queen; they can rule as long as they like because they have the sceptre. Economists may charge that this is unfair and counterproductive: a misallocation of resources that obstructs the rise of subsequent generations. Jackson, Madonna and Prince don't care about that, and neither, by the looks of it, does the Queen.

A long, long time ago, Jagger made it clear that he was not giving up his job, not only because of the money and the adulation, but because the evidence seemed to suggest that, even though it was indeed only rock'n'roll, he rather liked it. Prince and Madonna probably feel the same way: as long as the crowds keep coming, as long as they keep cheering, and as long as they keep paying, we're going to keep going out on the road. What Michael Jackson is thinking is anybody's guess.