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Saturday, March 26, 2011


Is there a limit to life expectancy?

By Philippa Roxby for BBC News

19 March 2011

Move over Methuselah. Future generations could be living well into their second century and still doing sudoku to boot, if life expectancy predictions are anything to go by. Increasing by two years every decade, they show no signs of flattening out. Average lifespan around the world is already double what it was 200 years ago.Since the 1980s, experts thought the increase in life expectancy would grind to a halt but forecasters have repeatedly been proved wrong. So can we go on living longer and longer? Is there a limit to how long we can survive into old age?

The reason behind the steady rise in life expectancy is "the decline in the death rate of the elderly", says Professor Tom Kirkwood from the Institute of Ageing and Health at Newcastle University. He has a theory that our bodies are evolving to maintain and repair themselves better and our genes are investing in this process to put off the damage which will eventually lead to death. As a result, there is no ceiling imposed by the realities of the ageing process. "There is no use-by-date when we age, ageing is not a fixed biological process," Professor Kirkwood says. A large study of people aged 85 and over in Newcastle, carried out by Professor Kirkwood and his colleagues, discovered that there were a remarkable number of people enjoying good health and independence in their late 80s and beyond.

With people reaching old age in better shape, it is safe to assume that this is all down to better eating habits, living conditions, education and medicine. There are still many people who suffer from major health problems, but modern medicine means doctors are better at managing long-term health conditions like diabetes, high blood pressure and heart disease. "We are reaching old age with less accumulative damage than previous generations. We are less damaged," says Professor Kirkwood. Our softer lives and the improvements in nutrition and healthcare have had a direct impact on longevity. Nearly one-in-five people currently in the UK will live to see their 100th birthday, the Office for National Statistics predicted last year. Life expectancy at birth has continued to increase in the UK - from 73.4 years for men for the period 1991 to 1993 to 77.85 years for 2007 to 2009. Life expectancy for females at birth has also increased - from 78.9 years (91-93) to 82 years (2007-2009). A report in Science from 2002 which looked at life expectancy patterns in different countries since 1840, concluded that there was no sign of a natural limit to life. Researchers Jim Oeppen and Dr James Vaupel found that people in the country with the highest life expectancy would live to an average age of 100 in about six decades. But they stopped short of predicting anything more. "This is far from eternity: modest annual increments in life expectancy will never lead to immortality," the researchers said. "It is striking, however, that centenarians may become commonplace within the lifetimes of people living today."


We do not seem to be approaching anything like the limits of life expectancy, says Professor David Leon from the London School of Hygiene and Tropical Medicine. "There has been no flattening out of the best of the best - the groups which everyone knows have good life expectancy and low mortality," he says. These groups, which tend to be in the higher social and economic groups in society, can live for several years longer than people in lower social groups, prompting calls for an end to inequalities within societies. Within populations, genes also have an important role to play in determining how long we could survive for - but environment is still the most important factor. It is no surprise that healthy-eating, healthy-living societies like Japan have the highest life expectancies in the world. But it would still be incredible to think that life expectancy could go on rising forever. "I would bet there will be further increases in life expectancy and then it will probably begin to slow," says Professor Kirkwood, "but we just don't know." Methuselah is not turning in his grave just yet.

[I wonder if there is indeed an upper limit to life expectancy. I guess that there must be. But what that limit is would be anyone’s guess. Is 200 or even 300 out of the question? With our increasing understanding of the human genome maybe in the not too distant future individuals might live to be 500 years old. If it’s just a matter of keeping the body successfully repaired a lifespan of beyond 500 years doesn’t seem particularly fantastic. Could people actually become immortal – or as immortal as it gets? I doubt if anyone living today will find out but our ancestors might look back on the present age and wonder how we coped surrounded by so much death.] 

6 comments:

smellincoffee said...

I'm dubious about the idea of our bodies evolving to take care of themselves better. How could it happen so quickly?

CyberKitten said...

A rather dubious comment I thought. Evolution doesn't work that fast at the best of times - and only then under intense evolutionary pressure.

I think a more logical and reasonable point was made shortly after: "it is safe to assume that this is all down to better eating habits, living conditions, education and medicine".

Hannah said...

While I highly doubt that I'll actually live to see the life expectancy to increase to 200 years, I'm not sure I would even want to live that long. We've created enough problems for ourself as it is, I can only imagine what the world would be like down the road - you might be able to expand life expectancy, but you can't control human nature.

CyberKitten said...

Hannah said: While I highly doubt that I'll actually live to see the life expectancy to increase to 200 years, I'm not sure I would even want to live that long.

200 is a while off yet. I'd like to live a long time only if I kept my faculties and control of my bodily functions. I certainly wouldn't like to be senile and incontinent for 100+ years!

Hannah said: you might be able to expand life expectancy, but you can't control human nature.

Oh, we probably can - once we understand the genetics of it. We're probably only a few generations away from designer people. I'm guessing that it's something our grandkids are going to have to deal with.

Hannah said...

"I certainly wouldn't like to be senile and incontinent for 100+ years!"

I hear you there. I've pretty much decided that once I require adult diapers its time for me to go.

As for controling human nature, it's more that I don't want to believe that we can do that. And I don't want to believe that we WOULD do it. When I think about it I just can't help but be reminded of Harrison Bergeron. It's frightening, but seeing as we can be a pretty ridiculous species, I won't get my hopes up too high.

As for living longer in general, for me its quality over quantity. What's the point of living an incredibly long life if we can't live it as we wish?

CRL said...

The term evolving is certainly being misused here. Even if these changes were occurring at a much slower rate, evolution STILL wouldn't be able to explain rising life expectancy, because it has no motive to keep people alive past their reproductive years.