There is, apparently, consternation in the world of tie manufacturers. The proportion of men in professional jobs who buy ties, a report says, has dropped from 70% in 1996 to just 56% today. And, to break that down (pay attention at the back, please), only 28% of office managers have bought a tie in the past 12 months. It is, however, floppy-collared architects and surveyors who are the biggest slackers: last year only a paltry 16% of them bothered to purchase a thin string of fabric to tie around their necks at 7 o'clock every morning.

These architects and surveyors are doubtless responding to the realisation that the tie is the sartorial equivalent of an appendix - an entirely redundant bit of kit left over from a much earlier phase of evolution. Just as it is several millennia since our digestive systems were required to deal with grass, it is at least a couple of centuries since men felt it necessary to protect their throats in the street from anyone making a lunge at the jugular with a sword (although nostalgia freaks will be queasily pleased to note that those times may be returning in certain parts of our inner cities).

Rejecting the tie, then, takes a man out of the symbolic combat zone and places him permanently in a "stand down" position. This might be a disadvantage in a court of law, which is why solicitors and barristers buy more ties than anyone else. However, in the team-based environment of an advertising agency, or even a call centre, it's probably a good idea if individuals don't feel permanently poised to fight a duel (at one point in history merely touching another man's tie knot was an invitation to trek out to a heath and start trading pot shots, which must have played havoc with staffing rotas).

What's more, by rejecting the tie, architects, surveyors and engineers (only 13% of whom managed to buy one last year) are also making a strong statement about not wanting to be defined by class. Ever since 1880, when the jaunty rowers of Oxford's Exeter College removed the ribbon bands from their hats and tied them round their necks, the tie has become a virtual microchip of information about where you come from and, by implication, where you are going. Schools, clubs, regiments and colleges all signal their specialness with a complicated pattern of spots and stripes that can only be decoded by those in the know. By refusing to be tied down in this way, members of what might be termed the post-industrial professions (financial advisers are also low on the tie-buying scale) signal that they hail from a world of flattened hierarchies and democratic interaction.

There is, finally, another very good reason for men to reject the symbolic freight of a tie. For while the necktie started off as a dandified bit of kit (as near as dammit to tucking a lace hanky into the top of your shirt), from Victorian times onwards it became austerely and dominatingly male. As a result, any woman wearing a tie in the 20th century was either very obviously in drag for her own pleasure or was being forced to send a slightly humiliating signal to the world that she wished to be viewed as a neuter (it's for that reason, surely, that disturbingly luscious adolescent girls are still obliged to wear a tie to school).

In these metrosexual days, however, for a man to insist on wearing a tie does not speak of a casual and unforced masculinity, but suggests instead a nagging worry about where the proper markers lie. For, viewed against a crisp white shirt, the classic dark tie forms an urgent pointing finger, dragging the viewer's eye straight towards the wearer's genitals. "Look," the tie seems to shout, like an embarrassing drunk in the pub, "there's no doubt about it, he's definitely all man."

· Kathryn Hughes's most recent book is The Short Life and Long Times of Mrs Beeton

kathryn.hughes@btinternet.com