These are not uplifting times for those who believe that, all things considered, it would be nice if looks weren't absolutely everything. The tidal wave of analysis about Madame Sarkozy's Dior (air hostessy or not air hostessy?), Madame's cheekbones (natural or enhanced?), Madame's nude portrait (arty or tarty?) was merely a sand-marker. This level of debate is played out weekly in the celebitchy magazines, and hourly on countless websites such as thesartorialist.com, an almost elegiacally earnest and tastefully laid-out pictorial blog dedicated to what stylish members of the public are wearing, or the slightly less tastefully laid-out forums with names such as rate-my-rack.org.

“Looks,” as the novelist Fay Weldon says briskly, “are still the most important thing for women.” This from Fay, who was brought up in New Zealand with one wonky mirror on the veranda and a mother who never told her that she was goodlooking, although she was, and is.

It's a long way from today's teens who, perpetually photographing their own gestures and grimaces on their mobile phones, make Narcissus look like a slob with image issues, or the thousands of eight-year-olds logging on to to missbimbo.com to order virtual pills and discuss boob jobs.

“Nowadays,” offers Weldon, “all little girls are told that they're beautiful by their mothers, even when they're not. We're terribly conflicted. We don't want appearance to be important, but almost everything we do reinforces that they are. Awful? Yes, if you think that there's such a thing as justice or people being born equal.

“But there are lots of things that are unfair about birth. Every small girl has to come to terms with the way she looks. In a way it's better now, because everyone can make themselves look better with cosmetics and surgery, but that in turn leads to an obsession that's becoming almost dystopian. Look how aspirational the WAG lifestyle has become - a lifestyle that's entirely predicated on how good women look and their ability to snare a man. They're the Becky Sharpes of the 21st century. We are in a moment of severe backlash against everything that feminists fought for.”

If you were a raging optimist, you might interpret the tireless investigative chronicling of Posh's nail extensions and Hermès bag collection as a victory against those doom-mongers who claim that these days we all have the attention span of a pair of hotpants. Not when it comes to arguing the case for and against the ones that Britney Spears recently wore we don't. You would dismiss theories that the media's saturation coverage - and the public's devouring - of the McCanns was partly a result of their being photogenic.

In an equally rhapsodic reading, the willingness of some sections of the public to post pictures of almost every region of their body for general inspection could be seen to hammer the final nail into the coffin of repressed, hidebound Britain. Confidence surely hath no greater manifestation than to download a picture of its nipples so that someone with a moment or two of downtime in an otherwise pressurised working day can mark them out of ten.

There is absolutely nothing new about “lookist” societies. Certainly since Chaucer, who wasn't exactly backwards about coming forwards with scathing descriptions of people's appearances, British literature has teemed with the pulchritudinous. Daniel Defoe's Moll Flanders, written in 1722, leaves us in no doubt as to the physical attributes of its heroine. “I had often heard the ladies say I was pretty,” says Moll, “and would be a very handsome woman.” Indeed, her prettiness is why Moll is able to become a gentlewoman - gentlewoman being a euphemism for prostitute, and prostitute being shorthand for a character likely to make for a compelling 400-page romp, something a plainer girl would, in 1722, be hard-pressed to do, being generally confined to cleaning out chamber pots.

Beauty was the only currency a woman could call her own. Hence this 140 years later, from George Eliot (a woman who was definitely more of a thinker than a looker) on Dorothea Brooke on the first page - in the first sentence! - of Middlemarch: “Miss Brooke had that kind of beauty which seems to be thrown into relief by poor dress.” Or this - from the first line - of Jane Austen's Emma: “Handsome, clever and rich.” Where the plain are allowed to exist (Jane Eyre, Northanger Abbey) there is, alas, often a whiff of disingenous Ugly Betty-itis. It's implicitly clear that Jane and Mr Rochester's unflashy looks are a manifestation of some kind of moral superiority. Either way, looks have become a battleground.

We do not need Desmond Morris to tell us that good looks are a biological preference, denoting as they did - and perhaps still do - good health and a gene pool that is generally innocent of cross-pollinating brothers and sisters. We also don't need me, a fashion editor who has done her share of critiquing other women's appearance (only those, I hope, who were fair game, although occasionally I have done the Devil's work) to tell us that henceforth we should repent our superficial ways and never speak harshly of Carol Vorderman again.

And the reason we don't need me or Dr Morris to point this out is because we have our Better Natures, which for centuries have been engaged in a duel with our instincts on this very subject. Better Nature advises you not to go for a man who looks like Brad Pitt but has the brains of a flower pot. Instinct says what glorious looking children you will have together. Better Nature tells you not to be distracted by whether pregnancy is making Natasha Kaplinsky's neck look puffy because she is an intelligent newsreader who is trying to explain the impact of the credit crunch on UK economic growth in 2009. Instinct is telling you that's all very well, but why does she have such terrible taste in eye shadow?

Better Nature is Baroness Kingsmill calling for an industry watch dog to curtail the amount of airbrushing in magazines in an attempt to present women with more realistic images. Instinct means that a woman with even mildly unconventional looks on the cover of a glossy magazine can have a deleterious impact on sales. Better Nature is society placing gags on itself under the aegis of political correctness. As Fay Weldon points out: “In polite company it is becoming increasingly déclassé to make nasty remarks about how people look. You can get sued for calling someone fat - so celebrity magazines act as a pressure valve for all the nasty things that one's thinking.” Truly, we are a society that goes to enormous lengths to delude ourselves into thinking that We Do Not Care About Looks.

If a balance is more or less achieved between these conflicting impulses, then that, arguably, is the best we can hope for. Let's not forget, as Michael Herz, the head of design at Aquascutum, says, “the huge enjoyment to be derived from taking an interest in how you and people around you look. Fashion [a business generating £47 billion a year in the UK] and make-up [£16 billion a year] can be power tools. The problem is that everything is increasingly bound up with appearance.”

One only has to see the Daily Mail's “Woman in parka shocker!” caption that accompanied a picture of Tessa Jowell on Monday to see how applying exacting sartorial standards across the board has become a habit. It's one thing to hold Madonna or Kate Moss up to scrutiny, or even to have fun with Carla Bruni, who is playing up to her new role sensationally - as befits a former supermodel. Inevitably, Sarah Brown got swept up in the forensic dissection of the French First Lady's outfits - and (hands up) The Times, along with other papers, ran unfavourable comments on the former's appearance. The entire female flank of the French Cabinet has recently had their wardrobes pored over as if they were auditioning to fill in for Cate Blanchett on the red carpet while she takes a spot of maternity leave.

In fairness, some of them looked as though they were auditioning. What's puzzling is the derisory tone of some of the commentary and the degree to which jibes about a woman's taste in footwear become a form of covert sniping about her character (the derision, by the way, doesn't generally come from fashion writers). Increasingly, looks are used to define women who never set out to compete by those rules.

“The fact that women are seemingly colluding doesn't make it harmless,” argues Sheila Jeffreys, the feminist author of Beauty And Misogyny: Harmful Cultural Practices in the West. “Sitting around bitching about how bad other women look won't ultimately make you feel better. Today's emphasis on looks - and the scorn heaped on anyone who doesn't conform - is incredibly unhealthy because it normalises painful and sometimes dangerous cosmetic procedures, promotes uncomfortable and immobilising clothes, fosters an epidemic of eating disorders and creates a tyranny of youth, under which no one is allowed to age.

“The principles of beauty have always been part of the mating ritual, but they're now routinely practised in the workplace. We're seeing that, even in politics, women are required to look a certain way: high heels, tighter-fitting clothes, lipstick. It's a free world, but in reality there's very little choice involved. There's virtually no challenge to the wall of thin, youthful images. The definition of what's attractive is becoming narrower.”

And while Western women are under pressure to show more and more of their bodies, Muslim women are increasingly veiling themselves. “It's a different manifestation of the same condition. I don't see either as empowering,” says Jeffreys.

Therein lies what seems to be the mother of paradoxes. More than 30 years after bra-burning and lipstick-abstaining, most Western women earn their own money, many work in worlds previously closed to them and a few occupy the top slots. Male babies outnumber females by 104 to 100 - so in theory women have never been more powerful. So why perpetuate, and even inflate, criteria that seem more relevant to women living in a harem?

Jeffreys believes that the answer may lie in the progress made in other areas. “To be successful in the public world, maybe this is the bargain women feel that they had to strike. It's as if we're saying ‘OK, we might be in the boardroom, but we are still sexually servicing you and aiming to please you aesthetically'.”

Or perhaps, as Robin Dunbar, a professor of evolutionary anthropology at Oxford, suggests, there is no contradiction in emancipated women apparently abiding by millennia-old ideas that value their looks above everything else. “In the evolutionary process, animals and humans are constantly evaluating the status of potential mates. One very potent display of status is conspicuous consumption. Beauty is now a purchasable commodity. A woman who is apparently conforming to a demeaning Barbie-doll figure or having all signs of character erased from her face may actually be flaunting her earning power and her ability to pay for fake breasts and Botox. The one thing that we can't as yet buy is height, which is why it's still fine for a woman to be short.”

If capitalism explains the present crescendo of narcissism, Nature explains the rest. According to Dunbar, a recent study of facial symmetry in all the British general elections since the Second World War showed that the more symmetrical a candidate's face, the higher the votes polled, while every US presidential election in the 20th century was won by the taller of the two rivals.

“Taller men are more likely to be married and have children,” says Dunbar. “In industrial societies where food is plentiful, women with hourglass figures are more fertile and therefore an aesthetic ideal. People who think looks don't matter are, I'm afraid, kidding themselves.”

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