David Lucas, commenting on a posting at my place sparked by the fact that a relative of mine by marriage is celebrating her hundredth birthday today, pours cold water on the likelihood of serious life extension much beyond a hundred:

I believe increased life expectancy is due to decreased rates of death, initially in childhood, later on in mid-life and now in tackling old-age diseases. There is remarkably little growth in people living significantly beyond 100-110.

The future pattern is likely to be most people living to around 100 and then dying of multiple organ failure.

Which I find bleak, but convincing. You read about occasional people of long, long ago living into very old age even by our standards, even as you wince at the tales of multiple infant death, then and later. The statistics of how medicine and food and hygiene have affected life expectancy until now are surely just as Lucas says.

But does that mean that it will always be like this? Maybe, but maybe not. Maybe medical magic will trundle slowly onwards, from stopping half the babies dying, to stopping half the surviving adults dying with the onset of middle age, to stopping three quarters of the wrinklies from dying well before they are a hundred, to keeping everyone alive even longer, by means now not known about. Or perhaps now known about but not yet widely bothered about, because now too difficult and expensive, and crucially (to use a morbidly appropriate adverb), too uncomfortable.

In other words, the reason nobody now lives beyond about a hundred and ten is basically the same reason that nobody, two hundred years ago, ever travelled faster than a galloping horse. The techies just hadn't got around to repealing this seemingly fixed law of nature. And then, one day - puff-puff - the techies got that sorted, and a few people did start travelling at twenty, thirty, forty, a hundred, two hundred, three hundred, five hundred miles per hour, quickly followed by nearly everybody else who could afford it.

We'll see. Well, I probably won't see, but we as in humanity as a whole may.

And if people ever do routinely live to be four hundred or more, what will be the results of that? A crate of Tesco Viagra for whoever can come up with the most surprising yet likely consequence of mass super-longevity.