Rockers Made Deals With Devil for Hair.

MICK Jagger has a big one. So does Paul McCartney. Bob Seger is so well-endowed he could give an inch away and still have plenty.

I am talking about heads of hair. Yes, hair. (What did you think I was talking about?) The oily, greasy, fleecy, shining, gleaming, streaming, flaxen-waxen stuff they sang about in the '60s. Hair.

The secret to longevity in rock 'n' roll.

Height is not important; Prince comes up to your belt buckle. Weight is not important; look at Meat Loaf. Good looks are not important. (Have you ever gotten close to a Spin Doctor?) Nor, if we go by Keith Richards' recent appearances, is it even necessary to be, technically, alive.

Keith has his hair.

What else matters?

I have this "scientific" theory. You may think I'm nuts. But here it is: True rock 'n' rollers make a deal with the devil.

They get to keep their hair forever.

Oh, they pay in other ways - drugs, death, having to wear spandex - but the hair stays on the head. Sounds incredible, right?

Consider this: According to statistics, one-third of all men are balding by the age of 40. One-third! So what are the odds of five men, all in their 50s - having taken enough drugs to make their teeth fall out, let alone their follicles - still having enough hair to, in some cases, fall into their eyes?

Ladies and gents: the Rolling Stones.

Get your ya-yas out.

And your blow dryer.

Want more proof? Take the Beatles. McCartney, at age 58, has the hair of a teenager. George Harrison, 57, a full mop top. John Lennon, when he died, was still shaggy.

Ringo Starr, on the other hand, is thinning badly. And of all the Beatles, who was the only one who didn't write, barely sang, and was, let's be honest, kind of lucky to be in the group?

I rest my case.

Rod Stewart? The man is 55; he still looks like a cocker spaniel. Steven Tyler of Aerosmith? More hair than Julia Roberts, and bigger lips. (Lips are another theory I have, but I'm still working on that one.)

Sammy Hagar? Ian Anderson? These guys should be cue balls! But they're hairy. They cut a deal. They learned from the legends.

Elvis Presley? Died with more hair on his head than an 8-year-old. Little Richard? He still has a coif. True, it goes straight up, like the Bride of Frankenstein, but that's a style thing.

Chuck Berry? He was born in 1928. He still greases back his hair. James Brown, the Godfather of Soul? He is 72 - with a mane that would make the Lion King jealous.

Now, maybe you're hearing this incredible evidence, and you're saying, "Mitch, have you been hit recently by a blunt object?" And I admit I am reaching the age when there is increasingly more hair in the sink than on the head. So this stuff matters to me.

But I cannot let emotion interfere with science. I have research. I have proof! This hair retention only works for real rock 'n' rollers.

This explains why James Taylor, a fine singer, but a folkie, is down to a few strands up top. And why Paul Simon, maybe the world's greatest lyricist - but never a rocker -- must resort to transplants.

Phil Collins is bald. What do you expect? He sings sap like "Groovy Kind of Love." And then there's Neil Diamond. Once upon a time, he rocked. Not anymore. Not coincidentally, he now takes hair from one side, flops it across his head and pastes it down, like carpet.

You start singing duets with Barbra Streisand, the deal is off.

Now, I will admit, there are a few cases that require explanation. How is it, for example, that Pete Townsend of the Who is bald, but Roger Daltry, his partner, still looks like a Raggedy Andy doll? And Elton John. For a few years, his music went soft, and so did his hairline. Now he has a wig and renewed popularity.

But in most cases, the theory is foolproof: Eric Clapton, 55, still rocks, still hairy. John Cougar Mellencamp, 48, still rocks, still hairy.

Sting, 48, sings about rain forests. Balding.

I rest my case.

So, OK. I know what you men are thinking. Lemme in. I want to be a rock 'n' roller. Too late. My guess is the devil comes about age 13, when you first pick up a guitar - and your soul seems as important as homework. That's when they make the pact. So, as they say in the sweepstakes business, if you haven't been contacted by now, there will be no prize.

But don't feel bad. Guys like Jagger and McCartney may go shaggy to the grave, but they will pay a price on the other side. That's for sure.

My guess is they get locked in a room with Neil Diamond music.

Which is enough to make your hair fall out.

Mitch Albom is author of the best-selling book, "Tuesdays With Morrie."