The concept of human immortality has always had huge appeal. Somehow, we never seem to accept the fact that it is necessary for us to die. This is perhaps most marked in our modern society, in which medical science has done so much to counter the causes of premature death. As a result, death has become something of a taboo subject, which most people are reluctant to face up to. This is well illustrated in the UK by the current confusion and controversy over the "right to die" of the terminally ill.
Lacking the ability to prolong physical life, some people have sought immortality symbolically, in making their mark on history through building territorial or business empires or producing works of art, literature or architecture. Most people probably see their children as providing some stake in the future, some continuity of their genes if not themselves. But it's immortality of the physical self which is seen as the holy grail; as Woody Allen put it:
I don't want to achieve immortality through my work... I want to achieve it through not dying.
Medical science is doing its best to oblige, with vast sums being spent on research into the causes of ageing; there's an entire scientific community devoted to finding ways to prolong life. Few people seem to question whether this is a sensible activity, although there are plenty of warnings in SF about the consequences should they succeed. The world's population is currently around 6.4 billion and is rising steadily; projections of future growth take the total to around 9 billion by the middle of this century, at which point the estimates more or less level off, with the population in the 22nd century being within the 8 to 10 billion band. In comparison, estimates of the maximum supportable population of this planet, taking into account all of the natural resources available and assuming a minimum standard of living (adequate food, housing, fresh water etc), put the sustainable capacity as between 2 and 4 billion. This is without taking into account the possible long-term consequences of climate change, which on current projections seem likely to reduce the area of productive agricultural land due to a combination of continental drought and the flooding of coastal areas. This is not a favourable scenario in which to come up with a method of prolonging individual life.
However, let us assume for the sake of argument that these problems are overcome in some way and we end up with a sustainable population. This doesn't remove the difficulties cause by a major extension of life expectancy. If the population is to remain sustainable it needs to be constant – which means that babies can be born only at the rate at which people die. The more successful medical science is in preventing ageing, the fewer children can be born. There will be an awful lot of frustrated parents out there. The whole shape of society would change, with children becoming a rare and precious commodity. Perhaps as a result the anti-ageing treatments would be reserved for the fortunate few – the rich, or those in political power – which would create a different set of tensions.
Even for those who might benefit from an indefinitely extended life, the consequences are not all rosy. For a start, the concept of retirement would disappear – most people would have to work for as long as they lived. Current pension arrangements are failing to keep up with the gradual increase in lifespan as it is; they would collapse completely if this were extended significantly, let alone indefinitely. People would only be able to retire if they accumulated so many savings that, when invested, they earned enough interest to keep up with inflation plus provide a liveable income on top. If future economies are anything like those of our current society, only a small percentage of the population would be likely to achieve that, and it would take most of them a very long time.
Clearly, indefinite life would have major implications for employment. Not only would the new immortals be faced with an eternity of work; they would become "job blockers", preventing younger people from gaining promotions or even from obtaining jobs at all. Sheer tedium seems likely to become the normal state of living.
When people discuss the benefits of extended life, they often talk enthusiastically about how they would at last have the time to learn skills they've always wanted to have: playing a musical instrument, learning a foreign language or becoming an artist. Frankly, I believe this is wishful thinking. Our lives are already long enough for people to do all of those things if they really want to. If they don't, it's because they're not sufficiently interested to put in the effort required, and that's not likely to change with a longer life. In fact, such abilities are best learned young, while the brain is still flexible enough to pick up new skills easily. For instance, if you want to learn to speak a foreign language without an accent, you normally have to do it before the age of twelve. As we get older and our personalities develop, out brains gradually get used to running in certain ruts; opinions become formed, skill-sets determined, creativity tends to diminish. As the saying goes, "you can't teach an old dog new tricks".
This particular consequence of ageing has been the subject of many epigrams. Here's a couple I like:
I used to dread getting older because I thought I would not be able to do all the things I wanted to do, but now that I am older I find out I don't want to do them. (Nancy Astor)
You can judge your age by the amount of pain you feel when you come in contact with a new idea. (Pearl S. Buck)
This mental fossilisation was well imagined in Larry Niven's short story "The Ethics of Madness", in which a man who has received immortality treatment is pursued in his spaceship for centuries by an automated weapon:
He was totally a man of habits now. He had not had an original thought in centuries. The ship's clock governed his life in every detail, taking him to the autodoc or the kitchen or the gym or the steam room or the bedroom or the bathroom. You'd have thought that he was an ancient robot following a circular tape, no longer able to respond to outside stimuli.
A way of avoiding the practical problems of physical immortality is to achieve a form of virtual survival. One version of this remains a strong selling point of religions; they have adopted the concept of the "soul" (or similar) which can survive after death. Even better, they try to tie their followers to them by promising a wonderful afterlife only to those who obey their laws (and therefore their religious leaders). This has proved compellingly attractive (for the religious leaders as well as their followers). The fact that there are many religions competing for customers, all offering different versions of religious law and blissful afterlife (of which only one, at the most, could be valid), doesn't seem to dampen enthusiasm.
More recently, futurologists and SF authors have explored the possibility of a different form of virtual survival – by having one's personality uploaded into a computer. This would be no simple matter as the human brain is vastly more complex than any computer yet devised or on the horizon, but let's assume that it becomes possible to create such a computer and to find a way of exactly duplicating all of the neural connections and electrochemical conditions which make up an individual's personality. What would result? Only a copy of ourselves, a kind of twin sibling, whose personality would immediately begin to diverge from our own. For ourselves to be "uploaded" would require the identification of a unique and fundamental aspect of our mind which was our true self, separate from the brain and capable of being transferred from one brain to another but not capable of being copied (otherwise it wouldn't be unique). In other words, a "soul". There is no evidence that this exists, and this notion puts such virtual immortality into the same camp as religious afterlife.
However, let's assume that such a personality transfer is possible. What would it be like? The idea of living a virtual life for ever has a certain appeal (especially if one is coming to the end of one's physical life) but all would not necessarily be rosy. Apart from concerns about the consequences of software bugs and viruses, what would it be like to be divorced from physical reality, to know that you didn't actually exist outside of an electronic box? I suspect that there would be a strong tendency for people cut loose from their roots, from their lifelong perspective of who they were, from any concept of purpose or reason, to slide gradually into insanity. After all, they'd have forever to think about it…
All in all, this hankering after eternal life looks like a worse idea the more I consider it. Our physical and mental development is constructed around the idea of seasons in life – of passing through stages from childhood through adolescence to adulthood, maturity and old age, before we shuffle off this mortal coil. Apart from the practical problems I've discussed, a major extension to the length of our lives may do nothing to improve the overall quality of our existence; and immortality of any kind (physical or virtual) would, I suspect, eventually turn out to be appalling.