Joan Smith: Oh, put a sock in it lads: it's OK to grow up

One day last week I passed an older (by which I mean about 40) couple embracing outside a wine bar. A younger person (by which I mean about 20) noticed them at the same time and I saw his mouth turn down in automatic distaste. Middle-aged people! Kissing in the street! Clearly, what these decrepit citizens should have been doing was staying indoors and drinking Ovaltine instead of upsetting healthy young people with an inappropriate display of passion. Alternatively, they could go and do stand-up in Edinburgh, telling the world how grim it is to be middle aged, let alone really old.

Frank Skinner apparently has nothing better to do these days than contemplate the contours of the urine-soaked mat next to his toilet, which must help his sex life no end. Then there's Sean Hughes (pictured), bemoaning his single, childless state and joining a queue of men of a certain age telling us how bloody miserable they are: lads into sads in no time at all. So what happened? Did they think getting older wouldn't happen to them and they haven't recovered from the shock? I've always thought that the laddish culture Skinner exemplifies is based on secret self-loathing, projected on to the world at large, and maybe there comes a moment when it just doesn't work any more.

The only thing that's unusual here is the gender of the people pounding this tiresome path. Middle-aged women cornered the "Oh God, look at those bags under my eyes!" market a long time ago, apparently believing that the rest of the word would go easy on them if they drew attention to their minor and perfectly natural imperfections. (Is there no end, I sometimes wonder, to female self-delusion?)

There's an entire genre of confessional writing out there which consists of someone cataloguing her physical decline in minute detail and, while it makes a change to have men doing it as well, I'm not exactly cheered to find even more people prostrating themselves before the pitiless deities of a youth-obsessed culture.

On the contrary, have I got news for them – and anybody else who thinks decrepitude and the cheerless slide into oblivion begins at 40. Last week the Queen guitarist Brian May, who gave up astronomy more than 30 years ago to grow his hair unfashionably long and strut the stage in a stadium rock band, got his PhD at the age of 60.

How many people of any age can claim to have played an admittedly execrable version of "God Save the Queen" on the roof of Buckingham Palace and completed a 48,000-word thesis on Radial Velocities in the Zodiacal Dust Cloud?

It's all a question of attitude, as my partner reminded me on Friday when he called from the summit of Mont Blanc which he had just climbed with two friends and an Alpine guide, all in their 50s.

Last week, two new pieces of research challenged the prevailing consensus that getting older is about nothing but loss and narrowing horizons, although even they were accompanied by a rash of infuriatingly outdated assumptions.

First, it turns out that the people who spend most time online (42 hours a month) aren't teenagers but the over-65s; far from being technologically illiterate and repeatedly asking their grandchildren to explain the meaning of phrases such as "the internet", people in this age group are perfectly capable of understanding the function of a modem and a wireless router. It's true that there are more 18 to 24-year-olds using the net but its popularity among older people is growing fast. They certainly don't deserve to be patronised with excruciating names such as "silver surfers", which is how much of the media responded to the survey.

The other new study is about older people and sex, and you had to burrow your way through a thicket of ageist assumptions to get to the good news that a high proportion of men and women go on having active sex lives well into old age. The research was carried out by the University of Chicago and funded mainly by the National Institute on Aging, whose representative – his age wasn't mentioned in the reports I read, although I can make a good guess – seemed astonished to find so many Americans having "a previously uncharacterized vitality and interest in sexuality that carries well into advanced age".

I mean, why is anyone surprised that three-quarters of respondents aged 57 to 64 have had sex in the past year? So have more than half of the 65-to-74 age group, and a quarter of those aged between 75 and 85. The deciding factor wasn't age at all, according to the study, but health.

This really does fall into the category of the absolutely bleedin' obvious, and it wouldn't cause a ripple if we hadn't embraced the myth that only the young have a sex life – and then only if they look like Justin Timberlake or Kate Moss.

There's a weird assumption that young, fit people who are obsessed with their looks must be having terrific sex, but you only have to look at the Beckhams, desperately trying to convince us how raunchy they are in a recent photoshoot timed to coincide with their move to Los Angeles, to wonder whether self-conscious narcissism is really an indicator of a hot love life. (Think Tom Cruise and Nicole Kidman in Eyes Wide Shut: I rest my case.)

It's only because we've got used to dismissing older people as past it in every sense that we've fallen for the idea that sexual attraction is solely to do with appearance; bodies aren't two-dimensional and sensuality involves a lot more than just looking. There is an element of luck involved, of course, and it's harder to enjoy sex and indeed life at any age if you happen to be chronically ill. But I can't help suspecting that Brian May PhD is a lot happier than a bunch of laddish stand-up comics who've just made the shocking discovery that becoming middle-aged isn't optional after all.

Alan Watkins is away