WHO, WHAT, WHY?
The Magazine answers...
Ten years after betting £100 that he would live to be 100, a man is celebrating his centenary birthday with a cheque for £25,000. Would you be wise to place a similar bet?
Having fun helps
It's the milestone that many dream of reaching, but few actually do. Alec Holden was offered generous odds of 250-1 when he was 90 years old that he would live to 100, much to the regret of bookmaker William Hill.
The mathematics of life expectancy calculations undertaken by actuaries are very complex.
Rates are usually applied to newborn babies and how old they can expect to live, if the current death rates applied. On current estimations, 100 would still command long odds - boys born in the UK will on average live to almost 77 and girls to 81.
Pretty grim - just 8% if you are a man currently aged 40; almost 12% if you are a woman the same age
Their chances of living to 100 are 18.1% for boys; 23.5% for girls, according to the Office for National Statistics. The odds for a 40-year-old male reading this article are somewhat longer, at just 8%. A 40-year-old woman has an 11.7% chance of reaching the magic three figures.
The major factors in determining life expectancy - genetics, getting cancer and being in a fatal accident, for example - are out of your control and down to luck, says Brian Stollery, an expert in human ageing.
"But other factors in people's control will have an influence," he says. "Having a healthy lifestyle, keeping fit. Preserving mental health requires keeping the brain active."
LIFE EXPECTANCY AROUND UK
At birth 2003-5
England Male: 76.9 Fem: 81.2
Wales M: 76.3 F: 80.7
Scotland M: 74.2 F: 79.3
N Ireland M: 76.0 F: 80.8
UK M: 76.6 F: 81.0
It's difficult to quantify how much these play a part, he says, but smoking is significant because it affects lung and brain capacity and increases cancer risk.
"But people smoke all their life and live to 100 and some never smoke and die of lung cancer at 50."
Where people live is not a factor in itself but there can be cultural influences associated with different parts of the UK, says Dr Stollery.
Stress can affect the heart so people who respond well to challenges in life can benefit in old age, while having a good pension helps buy some of the things that can increase well-being, he adds.
Women in the UK tend to live longer because their hearts are better in old age, say researchers at the Liverpool John Moores University. One evolutionary theory is that the hunter-gatherer tasks took their toll on younger men and the social importance of older women as advisers and passing on cultural meant they survived.
But once people reach 90, like Alec Holden, normal rules don't apply, says Danny Dorling, professor of human geography at Sheffield University.
"By the time you get to 90 you've gone past a lot of the things that usually kill you, the bulk of cancers apart from prostate, your heart is fairly sound and so people who die in their 90s tend to die from different things than other people."
Research suggests people at 90 tend to stop worrying about ill health and instead worry about people close to them, he says.
WHO, WHAT, WHY?
A regular feature in the BBC News Magazine - aiming to answer some of the questions behind the headlines
But it's not all good news at 90, says Mr Dorling. The chances of outliving your children rises significantly at that age and grief about losing a child is no less in old age than in young.
And younger people really ought to worry more about enjoying life and being happy, and less thinking about how they can make it to their 70s and 80s.
"It's largely out of their hands and if they're spending their time worrying about how to life forever, what are they living for?"
A selection of your comments appears below.
I recently did one of those life expectancy tests you see on the internet; you know the ones I mean. You put in details of your lifestyle and it works out how long you are going to live.
Apparently I've been dead since 1983.
I've seen daft statistics before but the ones quoted above aren't explained very well. A newborn boy child according to the above has a 18.1% chance of reaching 100 yet a forty year man has only 8%, so what is the chance of a 99 year old man reaching 100? Supposedly far less than the baby, if you take the above as a valid line of reason.
It doesn't add up properly if you see what I mean.
John S, Cheltenham
Happy Birthday Alec Holden! You look great. I Enjoy your celebrations and your money - you deserve it.
The article says my chances of living to 100 are "pretty grim" at only 8%. Not a good bet certainly, but look at how few people born in 1907 are still alive. 8% sounds fairly impressive to me, and would have been astounding to someone in 1907.
David Simons, London, England
These statistics may become irrelevant in the next 20-30 years. As medical technologies get more advanced including genetic engineering, stem cell therapies, advanced bionics, nanotechnology and rejuvenation therapies the human lifespan could be pushed out to 150, 200, 300 or more years. (Assuming you can afford it). I am 33 and, barring an accident or some quick acting cancer, I fully expect to see in my 100th birthday, looking and feeling no older than 50 when it happens. Indeed, if I don't get to see in the start of the 22nd Century I will be disappointed.
Mike, London, UK
Having heard Mr Holden on the radio yesterday and having listened to his answers to the inevitable 'what's the secret of a long life?' question I concluded that 'a wry sense of humour' is clearly a major benefit.
L Kirby, London, UK
All of us have only today! Live for it. Worrying about dying is wasting living. To slip into eternity is at least something to be relied upon!
Len Hart aged 74 living in France
How on earth can the chances of living to 100 be so much lower for a 40 year-old than for a child? Surely the chance of reaching 100 increases with age, the day before a 100th birthday they'd be very close to 100%. Even the odds stated for a 40 year old seem a bit strange; William Hill obviously thought that Alec Holden's chances of reaching 100 were worse than 0.4% or they wouldn't have taken the bet. A 90 year old has a far better chance of reaching 100 than a 40-year-old could William Hill possibly have been that far out?
Alan Davies, Edmonton, Alberta
It made my day waking up to Alec on the Today programme Tuesday morning. It was my birthday too, though I'm at the other end of the scale at 21. If I could guarantee to be as happy, cogent and jocular at 100 as he seemed I would sign on the dotted line for the elixir of life right now.
I would love to live to 100. What an achievement to have lived a whole century and to have been able to witness so many changes and seen so many things. Providing I wasn't a burden on anyone and I still had all my marbles, I think it would be marvellous. On the other hand - like the article said, you would start to worry about others. If my friends and family didn't have such long lives, you'd start to get very lonely and saddened by their deaths. Imagine my beautiful baby girl who is only ten weeks at the moment passing away in her seventies while I rumble on into my hundreds. Very lonely indeed.