I was 29 when I first became interested in the ages of literary characters. Re-reading Joseph Heller's Catch-22, I made the shocking discovery that somehow I was now a year older than Yossarian. How did this happen? Rebellious, wise-cracking Yossarian should be forever my senior, someone to look up to and secretly admire. An older brother or dodgy uncle almost. I shouldn't be able to overtake him. It didn't seem right. I was too young for such revelations.

Shaken by this, I got to thinking: not only was I a year older than Yossarian (and had still yet to kick noticeably against any pricks) but I was two years older than Hans Castorp when he came down from the Magic Mountain (and as readers of the Thomas Mann novel will confirm, he was up there for a very long time). Worse still, I was 13 years older than JD Salinger's Holden Caulfield. This was all very worrying to say the least. I went back to Catcher in the Rye and was relieved to discover that while I still enjoyed the book immensely, some of Holden's attitude and behaviour did strike me as a tad immature. Perhaps not quite as immature as they should appear to a 29-year-old, but enough to make me feel I was heading in vaguely the right direction life-wise.

Suddenly I was acutely aware of time moving on and dragging me along with it while Yossarian and his peers stayed youthfully behind. It was obvious that I needed to find a new yardstick to measure myself by. Measure myself how exactly? I'm not entirely sure. If part of the reason we read literature is to find out how to live, then I suppose I just liked the reassurance that someone reaching the grand old age of twenty-nine could still be living a life deemed interesting enough to be written and read about (Holden Caulfield hadn't quite lost his grip on me yet).

Thankfully James Kelman came along at just the right time with A Disaffection, for my money his best novel, and its angry youngish man, Patrick Doyle: twenty-nine with a life arguably more of a mess than my own. This was more like it. I quickly warmed to Patrick Doyle. I could imagine going down the pub with him. Admittedly, it wouldn't be the most merry of drinking sessions and most likely it'd end in tears, but it'd be interesting at least, and I liked to imagine we'd have a lot to talk about.

Then came 30. A bona fide milestone. One not made any easier by The Great Gatsby's Nick Carraway cheerfully describing it as the beginning of "a decade of loneliness, a thinning list of single men to know, a thinning briefcase of enthusiasm, thinning hair." Brill. This was about as reassuring to me as Beckett's we-are-born-astride-the-grave schtick must be to an expectant parent. But nevertheless, it was still nice to know I was not alone.

My interest in literary ages could easily have stopped there had I not gone one step further and started to make an annual list of characters who were the same age as myself. OK, perhaps this was a little on the nerdy side, but it was nothing to be too concerned about. It was when I caught myself musing upon whether I was too old for Kingsley Amis' Christine Callaghan or too young for Martin Amis' Nicola Six that alarm bells began to ring. And when my jottings were incorporated into that universal symbol of Serious Projects, an Excel spreadsheet, I realised that I had strayed beyond the realms of harmless hobby and was disappearing up the orifice of an obsession.

It was time to introduce some much needed objectivity into the project. What if I were to compile an anthology of literary characters – a male and a female example for each year from birth to death – with a quote for each from the novels pertinent to that age? It may even be possible, when the quotes are read in sequence, to view the different characters as a single life. And so, in a desperate attempt at legitimacy, I've set up a blog called Three Score & Ten which I'll be updating weekly with a pair of different examples for each year.

Being a stickler for tradition I've started with Conception and followed it up with Birth. This weekend I'll be adding Year One. Feel free to disagree with my choices: they're all based on my own personal reading so any suggestions for future reading are most welcome. I can't be the only person out there with this literary "kink" can I? Can anyone else say that they are currently the same age as X, Y, Z? Am genuinely interested to find out …