Who wants to live forever?

This fragment of poetry is the end of Lewis Carroll's poem 'The Lang Coortin',

I wot my coortin' sall not be Anither thirty years

For gin I find a ladye gay, Exactly to my taste, I'll pop the question, aye or nay, In twenty years at maist.

about a man who took thirty years to propose to the lady of his affections. Unfortunately, this softly-softly approach didn't work - the answer was no. Of course part of the humour is that we know that we don't have that much time to play with in making our life choices - in another twenty years he presumably would have exceeded the threescore years and ten which he might expect to live. But does this really have to be a limitation?

Every since people came to understand the nature of death, there must have been thoughts about how to avoid it. One of the earliest known stories, the 'Epic of Gilgamesh', has the quest for immortality as a central theme. Many religions offer the promise of an afterlife in a different realm, although many would rather stay in this one, as shown by the attempts to attain immortality by magical means such as the philosophers stone. More recently, medical advances has meant that people have begun to look at life extension as a real possibility. Transhumanists such as Nick Bostrom see this as something we should be striving for right now. Ray Kurzweil and Terry Grossman believe that if you can survive a couple more decades, then the technology will exist to extend your life. Maybe only a bit at first, but enough to live to see more technology which will mean that you can live even longer. Effectively you will be immortal.

As an example of the sort of technology which might become available is one to get rid of faulty mitochondria.

Bird mitochondria are more resistant to damage than mammal mitochondria, and so birds tend to live considerably longer than similarly sized mammals

Mitochondria are the parts of the cell responsible for its energy requirements. They originated from bacteria which were incorporated into the eukaryotic cell, and as such they have their own DNA. Unfortunately this DNA is more prone to damage than that in the cell nucleus, and much of ageing is thought to be caused by the accumulation of damage to mitochondrial DNA. But supposing we could get rid of cells with damaged mitochondria. Then the body would replace them with healthy ones, and the effects of ageing might be reversed. So how would you get at the damaged cells? Well various technologies are becoming available to do this. Typically, to get at every cell in your body would be very intrusive, but it might be possible to avoid this. I could imagine something like a highly tunable microwave, which was tuned to deliver a lot of heat to the proteins created by the mutant mitochondria, effectively cooking the cells containing them. You have your mitochondria tested, then Zap!, and after a short period of recuperation you're as good as new.

Some people might feel uneasy about this - they may think that we are rushing headlong into a 'Brave New World' without any consideration of what is really for the best. In fact as a society we rarely rush headlong into anything - such consideration usually does take place. We are used to the idea that, for something like human cloning, the population at large will have some say in the matter. Procedures which seem to go against nature will be debated and if they are found to be undesirable then there will be laws passed against them. But in the case of life extension it seems unlikely that this will happen. This won't just be one new technology, rather it will be a range of new ideas, and they will be seen primarily as medical treatments. Hence denying them to patients will be seen as deliberately shortening their lives, and it is this that begins to look like the story of 'Brave New World' - where there was compulsory euthanasia.

One of the problems with eternal life is that eternity is more than just a long time - it's infinitely long.

In A journey into gravity and spacetime John A Wheeler imagines a conversation about how far an interstellar spaceship might take him in the remaining 40 years of his life. I'll note here that he was nearly 80 when this was published - and he's still going strong nearly 20 years later. (Note: Unfortunately John Wheeler died shortly after I wrote this. See: Scientific American News)

What point would there be in doing anything today? Why should we read a particular book, when we might expect to read all books that are ever written. It's hard to see how we would spend our time. Indeed religions are moving away from the idea of eternal life as an infinite number of days one after the other towards a more abstract idea of eternity. But I'm not sure that inifinity is as much of a problem as it seems for life extenstion. They say that life begins at forty, and in a sense this is true. Up to that age people tend to be making their way in the world, and find it hard to think more than a few years ahead. When you pass that age, you begin to see that you might have another 40 years ahead of you to do what you want to do - and 40 years really is quite a long time. The trouble is that the amount of time you are likely to have left gets shorter as time goes on. Wouldn't it be good if it stayed the same. Is this just immortality in another guise? Well not necessarily. The trouble is that towards the end of our lives our life expectancy looks like the tail end of a Bell distribution e^-x². Its the fact that the exponent is x-squared rather than just x which is the problem, as it means that the probability of death increases every year. If our life expectancy looked like e^-x - like the decay of a radioactive atom - then the amount of time we might expect to have ahead of us wouldn't decrease as we got older. This sort of death rate has been achieved in a population of fruit flies, and there's every reason to suppose that it might be achieved with humans.

Life extension is going to happen, and with our understanding of the human genome, I could envisage Kurzweil and Grossman's 'Bridge 2' beginning to happen within a decade. As I've said above, I don't think that trying to think of ways to prevent it happening will lead anywhere. But neither do I think that everyone will want to live forever. What we do need to be discussing right now is how we will deal with treatments which have have a high probability of providing rejuvvination, but also have considerable risks. My mitochrondrial zapper is an imagined version of such a treatment, but real ones are likely to appear. Such treatments are unlikely to be get through today's licencing procedures , but I would think that plenty of people would jump at such a chance - will they be allowed to? In the longer term we need to think about a society in which people really do have a choice about how long they will live.