According to Carphone Warehouse most teenagers would rather give up sex than their mobile phones. One of the problems of growing older is that you know from experience that the old lose touch with the world, and therefore you know it must be happening to you, but you're not sure how. It's not the intelligence that diminishes so much. It's that the human brain is very good at loading culture (all the non-biological stuff that was not part of you when you were born but is now) but not so good at erasing it. This is not a design flaw. A huge part of the brain would have to be devoted to working out what should be dumped, and how the mind should restructure itself to deal with the absences. Much more effective to use the whole brain to load and run culture; it's a big thing the brain, and by the time it's full the body will be fairly clapped anyway. But that's why old people can't quite mesh up with the modern world, language and thought-wise, and why teenagers tend to sigh a lot and shake their heads. It doesn't matter to teenagers of course, and it shouldn't really matter to us, who should be getting ready to go, in our own good time. Mobile phones are a clear site of the kind of evolution which leaves us fading into the past. They have transformed human culture in a couple of generations. For me a mobile phone is just a fixed phone that works anywhere. But to the young the mobile phone is a whole inner universe, and their interaction with the world, its connections and its potential, their inner picture of what human life is, is as different from mine as mine is from my parents', who never really knew what a computer was. I can try to imagine what this virtual world which you can only enter through the practised and evolved use of the mobile phone is like, but I will be wrong, completely wrong. Today on the bus I watched a young woman hold up her mobile for her mother, a large woman, more butcher's slab than catwalk, to do something fascinating but repellent with her nose stud in. As in a mirror. When there were mirrors.