Age is more than a number when it comes to politics

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I think there is an unwritten law that any article or policy discussion about the aging population must start with some scary statistics to frame the debate. So here are a few from the UN. Between 2015 and 2050, the proportion of the world’s population that is over 60 will almost double from 12 percent to 22 percent. In 2021, there were 17 people aged 65 and over for every 100 people aged 20 to 64 (this is the so-called “old age dependency ratio”); by 2050, there will be 29 for every 100.

So far, so familiar. But what if these statistics are not a useful framework for the debate? What if “65 and over” is a bad definition of “old age”? In fact, what if chronological age is not a good criterion for aging at all?

The only thing a person’s chronological age really tells you is how many years they’ve been alive. Politicians worry about statistics like those above because they use chronological age as a proxy for other things they worry about, such as the number of frail or ill people who will need health or social care in the future , or the economy and economy. fiscal impact of fewer workers and more retirees, and so on.

It would be fair enough if chronological age were a reasonable proxy for all these things, but is it? A paper published last month by economists Rainer Kotschy, David Bloom and Andrew Scott argue that the basis of chronological age is “at best incomplete and at worst misleading”, because it provides “only limited information about the aging process “.

More obviously, people of the same age can vary greatly in how frail or ill they are. Using data from the United States and England on the physiological capabilities of over 50s, Kotschy, Bloom and Scott found that the healthiest 10 percent of the population at age 90 is close to the same frailty level as the median of 50 years. .

The average level of health and fitness by chronological age may also change over time. In the United Kingdom, for example, 70-year-old women in 2017 showed almost the same level of poor general health as 60-year-old women in 1981, according to the National Statistics Office.

If you use chronological age as a proxy for when people stop working, that also varies greatly by country and over time (and, of course, is particularly sensitive to changes in the state pension age). How significant is an “old age dependency report” that classifies the over 65s as “dependent” in a country like the United Kingdom, where the proportion of them in employment has grown by 27 percent in 2014 to 40 percent in 2024?

As Warren Sanderson and Sergei Scherbov, leading researchers in this field, I put it on: “Should the 60-year-olds in Russia in 1950 be considered as old as the 60-year-old Swedes in 2050? If not, is there a better alternative?”

The alternative proposed by Sanderson and Scherbov is to define the beginning of “old age” as the point when you have 15 years of life expectancy. Through this lens, the past, present and future look very different.

In the United Kingdom, for example, which had a strong increase in life expectancy until the last decade, the number of over-65s increased by 8.3 million between 1981 and 2017, but the number of people with a life expectancy of less than 15 years has fallen. from 7.4 minutes. And if you recalculate Old-age dependency ratios with this definition of “old” are lowest in all regions of the world except sub-Saharan Africa and Oceania (excluding Australia and New Zealand), and are projected to grows much less steep.

Of course, this might not be the right lens either – it will depend on the specific problem you are concerned with. Get questions about when people should be able to receive their state pension. In recent years there has been a proliferation of new “watches” which aims to measure a person’s “biological age” based on metrics such as blood proteins. Could they one day be used to determine each person’s state pension age, since any system that uses chronological age or average life expectancy is unfair to poorer people who live shorter lives?

Scott told me he wasn’t sure people would accept it, even if the clocks were scientifically robust enough. “Can you imagine two people of the same age, the same job… but one gets to (get his state pension) three years earlier?”

There is no perfect metric that can replace chronological age as a measure of population age. But once you see the definition of “old” as something other than the number of years people have been alive, it starts to look more malleable than inevitable, and those scary statistics about the rate at which we get older they seem more of a challenge. than a destiny.

sarah.oconnor@ft.com