Research into ageing is progressing to the point where a substantial increase in the human lifespan may become reality within a generation or two. In November 2010 Ian Sample of the Guardian reported http://www.guardian.co.uk/science/2010/nov/28/scientists-reverse-ageing-mice-humans#history-link-box ) on research at the John Hopkins University of Baltimore which has rejuvenated mice
“What we saw in these animals was not a slowing down or stabilisation of the ageing process. We saw a dramatic reversal – and that was unexpected,” said Ronald DePinho, who led the study, which was published in the journal Nature.
The question which humans need to consider seriously now rather than later are the effects , both on the individual and on society at large, of substantially increased lifespan.
Greatly increased human lifespans are potentially profoundly dangerous because they will detach humans from the lifespan evolution has prepared them for. it is a mistake to imagine that few people live to be old until recently, the very low average life expectancies in the past and the third world today were and are primarily due to infant deaths before the age of 5 with very heavy mortality in the first year. If you got past 5 you had a good chance of reaching adulthood and if you reached adulthood a sporting chance of living beyond 6o, with significant numbers living into what even today we would consider extreme old age. In short,. There have always been people living to the outer limits of the natural human life span so that any substantial increase in longevity will mean entering into virgin territory.
The greatest fully-authenticated age to which any human has lived is 122 years 164 days by Madam Jeanne Louise Calment of France. She was born on February 21, 1875 and died on August 4, 1997. However, few humans have ever got past 110. More and more people are living to be 100 in the developed world but the vast majority of those die not long after reaching their century. The average lifespan of those not struck down early by illness, accident or violence is probably between 80-90.
Suppose humans begin to live until the average lifespan is 160, about double the average of those living in developed countries now. That will mean some will probably live to 200+. Few would welcome a century or more of extreme old age with all its natural physical privations. But suppose that scientific advances slowed the ageing process to half it is now , with a man of 80 being the equivalent physically of a man of 40 today. Surely that would remove the obstacle to enjoying twice our current lifespan? It would probably not do so.
The person might be physically the same at 80 as they were previously at 40, but the psychological and sociological place they would be in would be completely different. Imagine having to live with the same partner for 120 years or more. Think of having to deal with your siblings for a century and a half. Consider the prospect of having to occupy yourself, with work or otherwise, for 120—140 years, with many decades of waiting for advancement. Some would adjust to it, but I doubt whether most would be able to beat off ennui . In this context it is worth thinking of the large number of people, mainly men, who die early in their retirement.
Of course, in all probability expanded life expectancy would not mean a life where the ageing process had been slowed proportionately to the increase in lifespan, but even if it had been, an average lifespan of 160 would mean twice as long suffering the physical and mental inhibitions of old age. Nor is it probable that all illnesses could be prevented or cured or damage caused by accidents or wilful violence repaired to restore the damaged individual to full health and capability. Imagine suffering from arthritis not for twenty years but forty years or having to care for someone suffering from dementia for half a century. The toll on individuals and the taxpayer would be vast.
To those problems would be the prime sociological one of how and when to breed. Even if puberty was delayed in the same way general agein and a person was likely to be 50 before they bred rather than 25, that would still leave 110+ years to know their children. And who would want to have a childhood stretching out to 50 years?
Then there would be the problems of vast population inflation even if breeding rates remained as they are today because twice the longevity equals twice the population and the subsequent pressure on resources.
If age was extended beyond 160 all these problems would multiply.
There would be the very real danger of the rejuvenation treatment being restricted to the rich or some other form of an elite. This would in effect create two species of homo sapiens. It would also provoke, sooner or later, great social unrest.
Could man ever be immortal even in principle? ? To achieve that would require the ending of all mortal disease and the repair of all mortal injury, but even then death from accident, war or murder would happen sooner or later. Perhaps it will become possible to “download” a personality with all its memories and then “up load ” the personality to an artificial body or more probably a clone of the original, but what would that be, you or something else altogether?