People are living longer and healthier in developed nations, with evidence suggesting we're living in good health to around a decade longer than our parents did. While it would be logic to think perhaps we'd managed to stave off the ageing process for longer, it's simply that we're maintaining our health for longer. Over the past 170 years, the average life span has grown at a rate of 2.5 years per decade, or about six hours per day in the countries with the highest life expectancies. The better health in older age stems from public health efforts to improve living conditions and prevent disease, and from improved medical interventions. Once it starts though, the process of ageing - including dementia and heart disease - is still happening at pretty much the same rate.

‘Deterioration, instead of being stretched out, is being postponed,' author and demographer James Vaupel told Nature. ‘We're living longer because people are reaching old age in better health.'

Vaupel says the chance of death increases with age up until the most advanced ages. ‘It is possible, if we continue to make progress in reducing mortality, that most children born since the year 2000 will live to see their 100th birthday - in the 22nd century,' he says.

Vaupel says this presents an interesting set of policy questions: what do these significantly longer lifespans mean for social services, health care and the economy? It also may be time to rethink how we structure our lives. ‘If young people realise they might live past 100 and be in good shape to 90 or 95, it might make more sense to mix education, work and child-rearing across more years of life instead of devoting the first two decades exclusively to education, the next three or four decades to career and parenting, and the last four solely to leisure.'

He suggests that one way to change life projections would be to allow younger people to work fewer hours, in exchange for staying in the workforce longer. ‘The 20th century was a century of the redistribution of wealth; the 21st century will probably be a century of the redistribution of work,' Vaupel says.

In such a theoretical field there are still more questions to be asked. Can the ageing process be slowed down or delayed further still? And why do women continue to outlive men - outnumbering them six to one at age 100? It is an interesting prospect indeed that more and more of us can look forward to blowing out 100 candles on our birthday cake and receiving a letter from the Queen.

ACSM #48