Howard Jacobson: The further north, the smarter you are

Up north we believe very little that we’re told. Hence the size of our brains

Been for two X-rays this month. I preferred the first.

Not the result, but the experience. I was lucky with the nurse. "My love", she called me. I'm fairly certain she was Polish, though I have never been called "my love" by a Polish woman before. Nor by a Polish man, come to that.

"Take your shirt off, my love," she said, which is an exciting request to a man my age, no matter that it's being made in a hospital. You grab whatever adventure comes your way. Even "Take your shirt off so I can slit you open from the nave to the chops without spilling blood on it" would do the business, so long as it came with a "my love".

Then she commented on my chest. "You've got big pectoral muscles," she noted.

I pulled my stomach in. "How big?" I wanted to ask, but my wife has warned me off initiating unnecessary conversation with nurses and doctors: it distracts them from making a reliable diagnosis, she believes. So I contented myself with a husky "Have I?"

"You have, my love. You only just fit on my plate."

By plate, she meant what you push against when they're photographing your insides. But it had the ring of "dinner" plate. "Her" dinner plate. My pectoral muscles were such that I was spilling over the sides of her dinner plate. This being a hospital, I pictured Salome receiving the head of John the Baptist on a dish. Which wouldn't have been so bad for the Baptist, I fancy, had she called him "my love", Polishly.

When I returned last week for a follow-up I was disappointed not to see her. Another nurse told me to take off my shirt, put my chest against the plate – just "the" plate, not "her" plate – take a deep breath, and that was that. No "my love" and no compliment on the size of my pecs. I asked my wife if she thought I'd lost bulk during the two X-rays. She didn't think so. If anything, she thought I'd put on bulk. So it was just the nurses: the luck of the draw. One made me feel what in Jewish Manchester we used to call a "shtarker", one didn't.

As it turned out, the second X-ray showed me to be clear of what the first X-ray had showed me to be full of. So it was good news. But who wants to be well in a world where the nurses don't notice how big your chest is?

Size, of course, isn't everything. Or so they say. In fact, "size isn't everything" is a statement that belies itself in the utterance. Money isn't everything, we tell people who have none. Life isn't everything, we tell people who are dying. Size, the same. "Size isn't everything, my love" – and at that moment we know that size is all there is.

Not that I have anything to worry about, size wise. I am from the north of England and new research has just shown that northerners have bigger brains than southerners. Something to do with light and visual processing, the effect of endless winters and sunless skies, and the eyes of northeners having to open wider to compensate. I'm doubtful about some of these findings – not the size of the brain but the reasons for it. The research was carried out by anthropologists working in Oxford, which, relative to where I come from, anyway, has to be considered south. Discovering that the brains of people living in Oxford, and no doubt Chipping Norton, are smaller than those of people living in north Manchester, these relatively small-brained southern researchers have come up with an explanation which takes away as much as it gives. We in the north have bigger brains, they say, only because, like primitive cameras, we need bigger apertures through which to process our native darkness into light. Believe that and you'll believe anything. But then if you have smaller southern brains you already do believe anything.

Up north we believe very little that we're told. Hence the size of our brains. We need the room to store our stocks of scepticism and mistrust, the shrewd independence of our judgements, our deep, broad sense of the ridiculous. I haven't done the measurements but I'd be surprised if you wouldn't find that George Formby of Wigan needed more cranial space than does Elton John of Pinner, ditto David Hockney from Bradford as compared to Tracey Emin of Croydon. If light does play a part in the difference then the way to understand it is that people with large brains seek out places where there's less light, or stay in places where there's less light, because they know that light distracts from the gritty business of living sceptically, mistrustfully, and intelligently.

Wherever we come from we accept that when we need to give our minds a rest and hope to live in the body for a while, we head south. The greater the light, the less of a brain we require. If you wanted an image of universal brainlessness what better could you choose than a glaring, body-strewn Mediterranean beach on which the uninformed, the unlettered and the slowly burning lie in uncomfortable proximity to one another reading Swedish detective novels and growing melanomas.

When I first moved south I was awed by the social confidence of southerners and the impression they conveyed of having known one another since birth, but I didn't find any of them as quick to make or get a joke, or as quick to understand a line of prose or poetry, as my friends back home. Intellectually, the person who impressed me most came from Scotland. Who he looked up to I didn't know, but on the basis that wherever you start from they're always smarter than you are further north, I have to presume it was someone from the Faroe Islands.

I'm never sure whether Poland counts as north or south, but consult it on an atlas and you see that the better part is north – of London at least. Certainly my Polish nurse was big brained. As for where the other came from – the one who didn't call me her love or register my pecs – my guess is Tierra del Fuego.