I want to say a word about hair. Since modern scholarship demands that I "situate myself", I should say that I am a middle-aged bloke with hair and a beard. I don't think of myself as a full-scale hairy man: more Jacob than Esau ("My brother Esau is a hairy man, but I am smooth," as the tricky Jacob puts it in Genesis), though nobody would call me smooth.

But when my best friend from school, whom I hadn't seen for 25 years, walked into my office, his first spluttered words were "You've got your air!". Since he had been a fabulously handsome young man, glossy haired and swaggering, while I was a dumpy and inward adolescent, there was a certain not wholly unsatisfactory frisson in this long-lost encounter with a once so bold and now so bald mate.

It's not always like that, of course. More often, thuggish youths shout abuse at me with crew-cut glee, and the occasional baffled child mistakes me for a younger brother of Hagrid.

But I am not alone. Especially in university towns, there are lots of men who grew up around the time I did who have not yet adjusted to the visual world of Ant and Dec. It's not just that there is a lot of hair about; it's the sheer mess of it. You see greying ponytails, thinning hippy manes, Einsteinian explosions lurking in maths departments, propping up the bars, and strolling in the streets. Most academic conferences boast a higher percentage of beards and ungelled hair than the national average.

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I suspect that most of these guys have a story something like mine. I grew up, happily enough for a dumpy and inward adolescent, in north London. The first battle with my parents was about the pink shirt and my desperate need to escape the white nylon or grey flannel that marked you out as uncool. Then it was the need to wear a parka rather than the duffle coat. But the fight that ran and ran was The Haircut. Long hair, for me and my friends, was a must. What else could complete the pink shirt and parka outfit but an Afro?

"Long hair was good enough for Jesus" became our mantra. It didn't matter that 40 per cent of the school was Jewish - that just added bite to the argument. ("And look what happened to Him," retorted my exasperated parents.)

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And then there was the musical. Singing Age of Aquarius while doing your Latin translation opened up the rich fantasy world to come of sex and hanging out - and all under the aegis of hair. Until then, all that remained for us was a self-consciously long-haired walk, LP cover clasped under arm, down Golders Green Road.

So the haircut, when it was enforced, was a total crisis. Today, the lovely Heidi brings me an Earl Grey and shows me her wedding photos from Thailand before massaging my scalp as she washes my hair. In those days, Mr Ritchie, without taking his cigarette from his mouth, talked across my head to the other barbers about horses and the Government and mercilessly hacked at my dry curls. When Freud described a haircut as a castrating emasculation, he didn't know the half of it.

So it is hardly surprising that the boys who filled the freshers' photographs of the 1970s, pimply-proud and self-conscious in the freedom of unrestrained hairiness, should still have their hair - when they can. Now I have a student son of my own, and when he comes home from university hairier than he left, his immediate plan is to get a haircut. I find myself saying, slightly too quickly: "Oh, you don't need to do that."

I try to sound offhand and liberal and unemotional. We're cool here. But every time I say it, my mind is flooded with the image of my mother telling me: "You need a haircut. Now." And I slip back into that angry and helpless adolescent under Mr Ritchie's casually cruel scissors.

Had I lived in the Victorian period, I would be comfortable in my fashionable hairiness, especially as a university figure. If you walk around the National Gallery's 19th-century rooms, you will see worthy after worthy with massive beard, baroque sideburns or cantilevered moustaches. The change has come within living memory.

A kindly and very old musicologist with whom I regularly had breakfast in my first job told me how as a child he had chased men with beards down the street yelling "beaver! beaver!". My own contact with the modern slang term "beaver" initially made the story confusing. It wasn't helped by the fact that the kindly fellow had a barely controlled hair fetish - for him the Seventies were very heaven.

But - I am nothing if not an academic - research reveals that his was not the fading recollection of a man with rather weird predilections. It was, indeed, common, especially after the First World War, for gangs of boys to torment the old guard of Victorian Britain for their hairiness, yelling "beaver, beaver". In a similar vein, a dear colleague told me, only half-teasingly, that her pre-teen girly magazines had warned her that men with beards were not to be trusted: "Anyone who would hide his face would conceal anything."

Perhaps that is why we haven't had a prime minister with a beard for ages, and why - with the strange logic of such things - Al Gore grew a beard as soon as he left the lies of politics and became a guru of the environmental lobby. It is certainly true that if you were going to play the "dinner party with a beard" game, while you might happily share the table with Sigmund Freud, George Bernard Shaw, George V and Billy Connolly, you would run a mile from Noel Edmonds, Richard Branson or Gary Glitter.

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I did shave - twice. The first time was because my dad said I needed to, and we duly shared a lathery bonding moment of incipient masculinity. The second time was to make sure I really didn't like it. So I don't waste time every morning scraping a shaving implement across my flesh, I don't look in the mirror much and remain quite unenthralled by the promise of "the best a man can get". As if.

But depilation has become all the rage, for men and women. And it is not just facial hair. As a classicist, I know that worrying about the nether regions goes back a long way. Any proper Greek statue of a man has neatly curled pubic hair. No statue of a woman has even a single strand. Plucking, singeing and shaping pubic hair - ancient Brazilians - was a stock joke on the comic stage in classical Athens.

Even the he-man of he-men, Hercules, does not have a hairy chest. But if we are to believe the word on the street, in the past decade men and women in unprecedented numbers are trying to become smoother than Jacob in every nook and crevice of their bodies.

Odd, the feelings hair produces. John Ruskin, in a famous but almost certainly apocryphal story, was so terrified on his wedding night by his wife's pubic hair that the marriage was never consummated. Apparently all the naked women he had seen before had been in pictures - completely smooth between the legs.

Back when feminists were feminists, the shaved and hairless female body was recognised as an infantilised object of patriarchy. The armpit became a battleground, and body hair was worn with pride. That has now been made to seem as outmoded as boiler suits. As Sex and the City has replaced The Female Eunuch, waxing has replaced reading as the route to self-improvement.

When hippies grew their hair, and skinheads had shaved theirs, the sign of the body was meant as a sign of a world view - a politics, if you will. That is partly why the Outraged of Tunbridge Wells always have something to say about hair. (William of Malmesbury gets the prize for the first Mr Outraged when he wrote that you could tell England was going to the dogs after the death of Henry I because men let their hair grow longer.) So I do wonder what is going on when so many people want to wax all over and express such strong feelings about hair.

You do hear mutterings about cleanliness - as if not having a Brazilian was dirty. But as any anthropologist will tell you, when an informant explains a cultural practice in terms of "cleanliness" you should always look for the deeper structures of taboo and fear. When people treat a hair on the leg like a hair in the cream cheese - so gross - you know that something anxious is happening.

So let me share one hair anxiety of my own. On at least three occasions when I have appeared on television and been reviewed in the newspapers for my brief talking-head performance, I have been referred to as an "academic with a beard". Now reviewers have been trained not to say "a blonde then said ...", or "a fat woman opined ..." or "a girl with amazing legs spoke up ...". But for a man, facial hair, it seems, is still fair game. Like shouting "beaver, beaver" in the street.

I don't think the Chief Rabbi or the Archbishop of Canterbury has to face beard jokes. But if you walk down the street with a beard and clothes that look a bit religious, you can be in for a rough time. Men marked out as Muslim by their beards and robes get as many hostile looks as women in burkas. Hasidic Jews avoid the stares of passers-by, but it's harder to blank when people wag their fingers and yell at you on the pavement and hold you responsible for all the evils of the world. In the heated days after 9/11, I was on several occasions searched three times on a single flight. Is it paranoia to think my beard might have prompted this special treatment?

Hair is remarkably personal for something so public. Changing hairdressers is traumatic, and, as Hollywood knows, changing hairstyles feels like an identity crisis. But as hair creeps down the body from the head towards the toes, it gets more intimate and more worrying. We anxiously police the boundary between the public and the pubic. So we distinguish between head hair, facial hair and body hair, as if a beard were not on the head.

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Perhaps beards provoke such feelings in our shaved and waxed culture because they sit awkwardly between the lovely tresses we want to display and the nasty hairs we conceal or remove. I don't know if that is true. But I do know that when I told anybody that I was writing a piece about hair it released a stream of stories about wigs, and dyes, and bad-hair days, and being worth it, and tickling kisses, and ... But nobody seemed able to put their rush of thoughts into any proper order. We've done Our Bodies, Our Selves; perhaps what we need now is Our Hair, Our Selves.