Live longer, work longer. As the developed world struggles with the cost of its greying population, a standard response has been to increase the state retirement age. In a decade or two, retiring at 67 rather than 65 will be the norm.
But is such a change fair? Across the developed world, better-off people in the higher social classes tend to live longer than do the poor. This gap has tended to widen, rather than shrink, in recent years. The result is that the poor get much less time to enjoy their benefits than the better-off.
This is not an easy problem to deal with. Since the rich always have tended to live longer, unfairness is built into the very idea of a universal retirement age. Nor are income levels the only determinant of longevity. There is also a gender gap: Women tend to live longer than men. They are not asked to retire later to redress the balance.
Historically, one factor behind the poorer life expectancy of working-class men was the nature of their jobs. A life down in the mines or unloading crates at the docks wore out the male body. In the course of time, the switch from a manufacturing economy to a services-based economy should reduce the importance of this factor.
So what else explains the gap between rich and poor? One possibility is access to health care. The better-off may benefit more from medical advances. Studies suggest that the longevity gap between rich and poor has widened by about a year in Britain since the early 1980s. In America the gap may have stretched by almost five years since the 1970s.
In Britain, thanks to the National Health Service, there is little difference by income level in treatment rates for heart disease or in the use of stroke-prevention drugs. In America, however, access to health care for the uninsured is patchier. Studies show that low-income residents in the northeast have both better access to health care and better mortality statistics than comparable residents in the southwest.
Lifestyle is probably more important still. In the past 30 years, one of the biggest factors in reducing mortality rates among 65-to-74-year-olds is related to a reduction in circulatory problems. Part of that is the result of better treatment, but the decline in smoking also has been a huge factor. An analysis of American counties found that a 5.9 per cent rise in the percentage of adult smokers increased premature mortality rates by nearly seven per cent.
A probable reason for a narrowing in the gap between male and female life expectancy in recent decades is the sharper fall in tobacco use among men. In contrast, the lifestyle gap between rich and poor has widened. Britons with no educational qualifications are five times more likely than those with higher education to smoke, to drink excessively, to eat poorly and to skimp on exercise.
The pattern varies between countries. In France there is less of a gap between the smoking habits of rich and poor. Nevertheless, a cross-European study of 40-to-65-year-olds found that mortality rates could be reduced by 23 per cent in men and by 16 per cent in women if those on low incomes behaved only as riskily as the better-off.
There is no consensus on why these lifestyle differences persist. Some argue that the stress of being poor leads people to smoke more and eat unwisely.
It seems likely, however, that there is a strong cultural component. In America there are marked differences in the health profiles of Hispanics and blacks at the same income level. It is probable that the decline in smoking among the better-off also has had a cultural element to it: The habit is no longer seen as socially acceptable in wealthier circles.
If the biggest reason for the longevity gap is lifestyle, it is better to tackle the health issues directly than to delay changes to the retirement age. Some countries' occupational-pension schemes -- for firefighters, say, or for the armed forces -- allow workers to retire early because of the hazardous nature of their professions. No one would suggest, however, that smokers or the obese should be allowed to stop work ahead of everyone else.
There are implications for government pension systems, such as those in America, which do not pay a flat-rate pension to all. The better-off are not only living longer but getting a higher income in the process. Currently only 85 per cent of America's Social Security payments are taxable, a tax break that delivers the biggest benefits to the well-off.
Given the longevity gap and the size of the deficit, that is one loophole that should be closed.