The girls are younger these days, but the heart-throb is as old as the hills. Shelley and Byron were pursued by crowds of squealing groupies. Roman hearts swelled at the sight of a well-formed gladiator. Chivalry and courtly love were crushes taken to their most formalised extreme: look but don't touch; pine away for love; fantasise until you're hot.
By the mid-20th century, business had harnessed the phenomenon for profit. Where previous generations had swooned for men of action, my mother went overboard about Laurence Olivier in Fire Over England - "when he jumped out of that window onto the horse, ohhh..." - Leslie Howard as Pimpernel Smith, a sort of 1940s Indiana Jones, and Clark Gable in Gone With the Wind. My friend Elva remembers lying awake in Canada with her tinny radio under the pillow in the hope of hearing Frank Sinatra's voice.
My first crush was Dr Spock in Star Trek. I was seven. Later I graduated to Sonny Osmond (you had to b e there), Kurt Russell in his buckskins in The Brothers and David Soul in Starsky and Hutch. Everybody else was in love with them too. Crushes are almost completely tribal until you're over the hump of 14, which explains the phenomenal profits turned by the boy bands. All it takes is appealing to the strongest character in each girlie gang and you're going to go straight in at Number 1.
So who does the current crop of early teens rate as prime meat? According to Sugar magazine , the top 10 faces that make hearts go pit-a-pat this year are: in the pop world, Ronan Keating from Boyzone, the band who are taking up the slack left by Take That with their cover versions of, among other things, the Osmonds' "Love Me For a Reason"; Damon Albarn, the perky, well-washed frontman from Blur; Liam Gallagher, surly singer in Oasis, and Gaz Coombes, the Supergrass singer whose sideburns are copyright of Planet of the Apes.
Hot telly properties are Matt le Blanc, the intellectually-challenged actor, Joey, in Friends; Jared Lito, a Matt Dillon/James Dean hybrid who sulked his way through the excellent but ill-fated My So-Called Life, and Paul Nichols, who played a heart-throb in the BBC kids' series The Biz and is about to boost EastEnders' ratings when he joins its cast tonight. The only film star is Brad Pitt, the callipygian beauty on whom quite a lot of grown-up girlies also have crushes. One doubts, however, that the teen market covets him for his magnificent performance as a bearded, brain-dead mass-murderer in Kalifornia.
The last two are interesting. They are Jamie Redknap of Liverpool FC and Trevor Sinclair of QPR. Both are, according to my colleagues on the Sports desk, "sweet, tall and nicely formed", but crushes on footballers are anathema to my generation. Boys had crushes on footballers, not girls. But the advent of opera, weeping Gazzas, spades of money and the prevalence?? had made soccer players safe. Wonders will never cease.
So what are the ingredients that make a teen heart-throb? Well, look at this list and common factors become apparent. Liam is the exception in all of this, but it's possible that crushes on Liam are more a reflection of older sisters' tastes. Firstly, none of these people are dangerous. Well put together, yes; well muscled, some of them, but they don't project the threat that, if you were alone in a room with them, things might get out of hand. They are all, with the possible exception of Gaz, easy on the eye, but in an unchallenging mould: noses not too big, eyes white and bright, hair clean and cared for, limbs lean and usually long.
Apart from Jared, whose moody eyes and floppy fringe brings out the taming instinct, the wish to nurture, they are crowd pleasers: chipper, smiley, having a good time. You get the feeling that their mums still wash their clothes. These boys are just like the real boyfriend you could end up having, only better.
The teen-throb has a quality, though, which distinguishes him from the chaps the older girls go for. It's to do with that horrible phase their fans are gong through: puberty. Suddenly you're 12, and everything you took for granted is pulled out from under you. Your body has gone haywire, you're sprouting lumpy bits, encountering viscosities you never knew existed. Your friends change their fealties weekly. Your dad, unless you're unlucky, starts to keep his distance. School is no longer an easy coast. Gangs form and you never know when it's gong to turn on you: there is nothing more spiteful than a gaggle of teenage girls in full cry. All your terms of reference are turned upside down.
Which is where your personal idol helps. Your attitude to masculinity is ambivalent: you like it, but it's deeply unfamiliar. Your average top pop boy, from Take That to David Cassidy to John Lennon to Cliff Richard, has at least some of these qualities: he's slim, has long legs, small features and never, ever has conspicuous body hair. Another nail in Liam's coffin. The members of Take That, famously, used to shave theirs in order not to cause offence. Body hair it too testosterone-y for someone who's just getting used to oestrogen. Adolescent girls want boys, sure. But what they really want is boys who are good-looking versions of adolescent girls.