A user's guide to age: We can't truly become 'amortal'

If you lived to, say, an active, sentient 120 or more, you'd want to die anyway from sheer irritability, says one of the characters in the great American poet/novelist Randall Jarrell's 1954 novel of campus life, Pictures from an Institution. Things would repeat themselves, the great cycle of life – hatched, matched, dispatched – would continue and you'd be out of sync. Seen it all before. Fed up.

But not if you'd had the 2011 mindset Catherine Mayer calls "amortality" in her new book, and not if you were surrounded by equally well-preserved contemporaries. People such as Ab Fab's fictional Edina or the real-ish Richard Branson. You'd forever be finding new things to be interested in, challenged by. You'd still be doing death-defying stuff, fighting the dying of the light. Down with the kids. Out there in the hot cities, the emerging countries.

Amortality is the mass condition where people don't act their age and don't acknowledge death. Amortality, once exotic, is now commonplace in the wealthy world. It's your 49-year-old wife, lean and fit in Prada and Topshop, swapping clothes and downloads with her best friend, your 18-year-old daughter. It's groovy old men, not grumpy ones. It's nine-year-olds doing what 1970s teenagers did. It's the increasing jumbling of proper ages and stages (or to use a popular 1970s word, passages) that seemed to define an earlier world, write the script and put things and people in their places, resigned to the inevitable. Memento mori.

It's about much more than living longer and the huge projected rise in the number of centenarians (being over 100 still won't be that great in the foreseeable future – if ever). And much more than people just looking and feeling better in the "60 is the new 40" sense.

It's about the "Having It All" – how handy the language of 1970s Cosmo is here – side of things. Or secular bourgeois individualism gone mad, if you prefer a more comfortably political, judgemental language. If, increasingly, better-off, better-educated Westerners can move around what once looked like the solid walls of everyday life – when and whether to marry, have children – how often and in what configuration, if Viagra makes for a sexually active old age. If precisely the people who can afford to retire from work don't want to, because it's so exciting, so defining, then you've got an interesting problem on your hands.

Of course, it's still class- and education- and opportunity-based. Of course, it's particularly American – and particular parts of America too. But it's absolutely not just California any more. We're doing it, too, and all the obvious indicators confirm it. Age of marriage and child-bearing is constantly rising here, especially among the careerist, self-realising middle classes. The divorce rate, having shot up, is allegedly stabilising, but for how long? The relative normalisation of seriously old mothers and even, at the margins, the vocabulary of "gender reassignment", are all evidence of a life to be optimised, not endured. And then prolonged.

At the back of Amortality: The Pleasures and Perils of Living Agelessly, Catherine Mayer has a handy Cosmo-like quiz called "Are you amortal?" She's pretty much off-the-scale amortal herself. Younger-looking, of course, than her age (though not yet stretched and sewn), she's a very Anglicised international kind of American, settled here, married to one of our musical National Treasures, Andy Gill of the post-punk Gang of Four. Electively childless, three-quarters Jewish, the child of clever, active amortal parents who are still going, she's got all the predisposing factors (her mother stayed in her London job into her sixties because she was assumed to be a decade younger).

Until the 1980s, Brits at most social levels thought the questy American journey into the self, into everything Californian and personal growth-y, was obsessive and absurd, beyond parody. Get a grip. Take a long walk. And the outwards and visibles of it, the extreme makeovers, the renovated and redistributed flesh, the eerily perfect teeth, were frightening (and, for upper-class Brits, very naff-looking, too). But we're doing it now at every level; Brits – men and women – are much higher-maintenance than they were. Defiantly straggly teeth have been reorganised and whitened. In any provincial city, quite depressed northern ones included, you're never far from someone who can liposuck, Botox, depilate or spray-tan. And that's only for the boys.

Although we're not quite at that point where, as Mayer noticed with the wives of the German ultra-haute bourgeoisie, scientific beauty has produced rooms full of identical-looking ageless women, we're well on the way. But far more important than all this is the attitude that drives it; the expectation that all those early-1960s "Youthquake" rights to a sex life, a hot wardrobe and perpetual entertainment that was sold as generational could then endure practically for ever. That 70-somethings could fight for the right to party. The brilliant broadcaster and comedy writer Danny Baker presciently described teenageism in the 1980s as "a little blip in Western history". We can see it now; seven-year-olds and 70-year-olds can both live like 1960s teenagers now.

This was all stoking up somewhere else 30 years ago. When I first started going to New York, the great Fifth Avenue bookshops were miles better than ours. They spread new books seductively on tables, they merchandised ideas for a hyper-literate, talkative town that loved them. That was how I came across Tom Wolfe's collection of essays Mauve Gloves & Madmen, Clutter & Vine and, crucially, his Me Decade and the Third Great Awakening (1976) essay about the great quasi-religious tide of self-involvement in late-1970s America. And Christopher Lasch's classic The Culture of Narcissism (1979), which argued that America had reached such a decadent fever pitch of indulgent introspection that they'd never be able to do anything worthwhile again. And then there was The Serial (of Marin County, 1977), a delicious satire of extreme Californian life, a world of hot tubs and imported pick'n'mix religions. I knew – every Brit did then – how to write it up in an ironic, distanced, sarky, snobby way, but I actually loved it. Talk about doing "your own thing in your own time", as the hilarious Peter Fonda character in Easy Rider (1969) called it. In the 1970s and 1980s, you were honour-bound to diss everything about late-1960s popular hippiedom but it still hung heavy and positively radio-active over the way young American culture was developing. And we knew it'd hit us eventually.

All this, as Catherine Mayer points out, is best expressed by that brilliant bit of advertising copy for L'Oréal "Because I'm worth it" (1973), a line so sharp it explains and dramatises everything from organic food to the 1990s Luxury Fever in just four words. (Tom Wolfe, interestingly enough, focused on an earlier example of crucial copyrighting in The Me Decade, Shirley Polykoff's inspirational Clairol ad for bleach: "If I only have one life... let me live it as a blonde.")

While Brits were still thinking that what can't be cured must be endured, a significant minority of Americans were saying you could reset the cycles, that women could be Feminine Forever (Robert Wilson's great HRT best-seller of 1966) and blonde too. And, the most glorious absurdness of all, that death was optional.

That was when – the early 1980s – we first started to see sarky, snobby, etc, British television documentary-makers' programmes about the growing group of American life-extension pedlars predicting 200-year lifespans. And that was when we first started to hear about cryogenics – sticking rich people's corpses into a sort of glammed-up chest freezer affair in the expectation that they could be revived when the medical technology had developed. You can probably get it done in Hartlepool now if you ask around.

The idea of living the life you want at whatever age is mainstream now, central to the unwritten constitution. And that means, most famously, dress codes and every other bit of cultural consumption going. Added-value sports-derived clothing as middle-aged daywear, even workwear, the mid-life sports cars and Harley-Davidsons, were surely written in anticipation of Viagra.

In an ageing population where a lucky subset of the younger old is fit, active and rich – still competing, still playing – marketing has taken its time to acknowledge those new markets, and to target them. The culture of British marketing and advertising people remains hopelessly, slavishly chained to a completely outdated idea of youth as monopolising new ideas and new media platforms. It all comes from the ancient mythology of our glorious youth culture. And it's all rationalised in the idea that any association with anyone over 50 will be off-brand – whatever the brand is. This still inhibits marketeers from engaging with amortals, who now include a mass of professional "early adopters", people they should be watching and cultivating. But they'd rather not know.

It's potentially embarrassing, of course. The language hasn't caught up, so it's a vocabulary of catcalls from another age – "mutton dressed as lamb", "The Oldest Swinger in Town" (1981) – with their implications of Third-Agers wanting to pass for youth, pathetically stealing the clothes and the clubs and the language. The reality – like the reality of "blended" families with stepchildren at staggered ages – is much more complex. Take the growing live performance market for old-rocker 1970s bands, with their oddly mixed audiences, dominated by their original fans in their fifties, but with their children there too and completely new cohorts of the fan base recruited online.

Many of these markets have developed at their own pace, beyond the directional marketeers, and certainly beyond the cool-hunters' gaze. Cool-hunting, a curiously dated Nathan Barley-ish occupation staffed by stylists from fashion-land and wannabe anthropologists from the little fashion/culture magazine sector – Dazed and Confused, i-on, Jockey Slut, Zoozoom – that boomed in the 1990s, was always focused on Spectacular Youth Out There. Find them in their ghettos and favelas, infiltrate their riveting lives and report back fast, on the clothes!, the music!, the scene! to Nike, Coca-Cola or Benetton, any of a clutch of huge global companies built on the big idea of Youth Culture. But while these enterprising 30-somethings were down there with the kids with their new-generation digital cameras, the real story was on their own doorsteps. The way we live now – amortalising away.

Instead, Catherine Mayer, the Time bureau chief in London, representing an altogether older kind of American/International brand, has found it for us, pulled it together. The real story of where the past 40-something years have ended up. She's done it terribly well, combining the Time approach and disciplines, the middlebrow mission to explain the world to the American suburbs with her own direct experience as the amortal daughter of pioneer amortalists. And her experience at the heart of things in fast-track musicland from the late 1970s on, moving through the generations and the venues, seeing people curiously still in there and at it, performing, touring long past their traditional span. What do you do when the first mass-generation of Professionally Young working people in these post-war Youth trades serving post-war teenage consumers, becomes middle-aged and then old? As Mayer says: "Although I'm amortal in many senses I know it's got many awful manifestations – and I'm quite conflicted."

What she means is that there's a mass of unsustainable organised hucksterism in amortality – the conspiracy of plastic-surgery clinics, cosmetics advertisers, resort developers and media owners – selling the dream of sexy hyperactive old age for everyone.

And there are the inexorable and uncomfortable demographics of old age. Research is showing how every step up the social scale gives you a longer life expectancy, and how these extra increments of middle-class education help to hard-wire brains against Alzheimer's. The best surgeons and dentists are hugely expensive and, if they ever really develop the Holy Grail procedures that arrest, even reverse, the granular reality of ageing, – unstoppable change and decline at the cellular level – then you'll have one of those 1970s sci-fi Logan's Run situations realised. There'll be gated communities of the global rich who are practically immortal because they're signed up for a couple of hundred thousand a year. While the rest of humanity withers and dies in all the old familiar ways. Amortality in this sense is lined up with inequality.

But in the meantime, as Catherine Mayer points out, no one's within a country mile of achieving the real life-extension breakthrough. While people such as the curious arch-immortalist Aubrey de Grey, chief science officer of the Sens Foundation, develop the rhetoric, they haven't got the pills yet.

And the lifespan gains of post-war prosperity are starting to show diminishing returns. There seem to be very clear limits (120 looks to be absolute top-whack now). And there are obvious problems in maintaining quality of life for the forthcoming masses of Seriously Old Survivors. Alzheimer's, already affecting 8 per cent of over-65s and set to rise, is the most obvious example.

Meanwhile, there's a modest counter-trend growing, one which reintroduces and fetishises the old symbolism of death and succession. The memento mori skull in the 16th-century swagger portrait, the black hooded scythe-wielder at the pillared door, and the nether world flaming away just underneath your lovely new-old honed marble floor.

'Amortality: The Pleasures and Perils of Living Agelessly' is published by Ebury (£12.99). To order a copy for the special price of £10.99 (free P&P), call Independent Books Direct on 08430 600 030, or visit www.independentbooksdirect.co.uk.