Forget the ageing population, we’re actually getting ‘younger’

If you follow the debate on “population ageing” you could be forgiven for thinking that it is a bad thing; growing numbers of older people mean greying societies, struggling to maintain

pensions, welfare, health and social care systems. But such arguments ought to give us more pause for thought than they do, for three reasons. Step forward those who would prefer to die

sooner? Or are happy to volunteer friends or relatives? As the driver of population ageing, people living longer is a good thing, full stop. Also, while individuals are born, grow old and

die, populations do none of these things. The metaphor of “ageing” actually refers to the age structure of a population: how many young, middle aged or old people it contains at a point in

time. The share of older people is growing because fertility and mortality are falling. The world population is now more than 7 billion, having doubled in just over 40 years, so falling

fertility is very good news. Falling mortality produced by changes such as better public health (better diet, cleaner water, more exercise, less smoking, better health and safety at work,

fewer fatal car crashes) and more effective medical technologies and treatments, increases life expectancy. This is good news. A more technical reason – but perhaps the most important – is

that in many countries, including the UK, the population is actually getting “younger”. The UK population is younger now that at any time in the last 170 years. We know a lot about this from

1841 – the date of the first proper UK census. We usually think of age in terms of the number of years lived. Almost all of us know how old we are. But our age has a second, less

immediately visible element: our remaining life expectancy, or years left. As individuals we don’t know when we are going to die. But for groups of people or populations we can measure this

very well – an entire industry, the actuarial profession, is devoted to it. The continuing decline in mortality means that at any age, remaining life expectancy has been increasing. So if we

look at the average years lived (age) of the UK population, it has been rising (from about 21 in 1841 to 40 today), both because of falling fertility and falling mortality. But if we look

at the average years left of the population, this has also been rising, from 39 to 43 years. The increase looks more modest, but remember these are the years left still to live of a

population twice as old as its 19th-century predecessor. This is not some obscure technical point, of interest only to demographers, statisticians or policy wonks, because years left or

remaining life expectancy often relates more closely with other issues we are interested in than our age. One example is the cost of hospital treatment or acute medical care. Several studies

have suggested that if we take account of life expectancy, there is no relationship between age and costs of hospital treatment. The bulk of expenditure occurs in the final stages of life,

regardless of the age at which this stage occurs. But given that much of the increase in the healthcare bill is driven by technological innovation (new treatments become possible) and that

most medical treatment is delivered to older people, this does not mean that longer lives will have no impact: rather there will be more things that medicine is able to do, provided

politicians have the backbone to collect the taxes needed to pay for it. What the rise in years left at any age tells us is that “age” measured only by years lived is a woefully unreliable

measure if we want to make comparisons over time, since the correlates of age change. Paradoxically, this is something better understood by popular culture, when we say things like “50 is

the new 40”. It makes little sense, for example, to look at trends over time in the proportion of the population older a fixed age boundary (65, 80 or some other number) since as remaining

life expectancy changes, the characteristics of the people at this boundary also change – and in effect they become “younger”. The debates around “population ageing” centre around the idea

of burden – in terms of costs and health. And it also serves well those who are campaigning for more funding for particular issues. But we’re also ageing healthier. And how our health

systems work depends on a more complex series of issues that would be refreshing to hear about.