By Paul Rincon
BBC News science reporter, St Louis
The age of retirement should be raised to 85 by 2050 because of trends in life expectancy, a US biologist has said.
A longer life could mean a longer working life
Shripad Tuljapurkar of Stanford University says anti-ageing advances could raise life expectancy by a year each year over the next two decades.
That would put a strain on economies around the world if current retirement ages are maintained, he warned.
He also told a science meeting in St Louis that 50-year or 75-year mortgages might not be unusual in the future.
Dr Tuljapurkar was speaking at the American Association for the Advancement of Science annual meeting in the Missouri city.
"People are going to do things they didn't get round to in their working lives. Current institutions are really not equipped at the moment to deal with such long lives," he said.
"We are going to have to plan a lot more carefully, which people are not very good at."
The Stanford researcher has been looking at relationships between historical trends in ageing, population growth and economic activity.
Based on this, he came up with a scenario in which anti-ageing technologies would increase the most common age of death by one year per year between 2010 and 2030.
Dr Tuljapurkar then applied this scenario to four countries: the US, China, Sweden and India.
He found that his projected trends in life expectancy would have profound effects on the economy, lifestyle and population demographics.
In the US the cost of social security and medical care would almost double if people retired at 65
"It might be possible to go through two mortgages, for example, or even have 50-year or 75-year mortgages," Dr Tuljapurkar explained.
In the US, the cost of social security and medical care would almost double if people retired at 65 under Tuljapurkar's scenario.
But an increase in the retirement age to 85 would bring costs down to today's levels.
However, these trends would also create a "permanent underclass" of countries where opportunities for increased life expectancy were not the same as in the industrialised world.
"We can't even get retrovirals to some countries now," he told journalists.