My granddaughter will be four years old next week. If medical science continues to improve at its current rate, she will live to be 103. More precisely, half of her generation will still be alive at 103. I have been trying to work out how to prepare her for such a long life. I am reading “The New Long Life” by Andrew Scott and Lynda Gratton. Their book is precisely about how to live a life of 100 years. They tackle issues like staying fit and healthy, what will happen to families, communities and work. It offers guidance for Education, Government and Companies.
Chronological Age and Biological Age
Early in the book, they introduce a very interesting idea : time inflation. Suppose I tell you the price of a loaf of bread in 1990 and the price today. I ask you which is more expensive? Most people will correct for monetary inflation. We correct for the value of money at different times. The spending power of a pound or dollar has gone down, so we index. Scott and Gratton suggest that we have to do the same thing for time.
We have seen in these Newsletters that the rate of decline in our health and intellect is slowing with each new generation. Time is moving slower and a chronological year is “worth less”. A 70 year old in 1990 is very different to a 70 year old today. In Newsletter #027 we compared UK health data from 2017 and 1997. In that twenty year period, healthy aging extended by thirteen years. Medical science, nutrition and exercise had pushed back the disability that comes with the Fourth Age.
Newsletter #030 looked at longitudinal data on the decline in mental ability. We saw that a 70 year old in this generation would score the same on mental tests as a 60 year old in their parent’s generation. Newsletter #029 provided one answer. The separation of brain and body is an artefact of human thinking. They are an integrated whole. A healthy body increases the blood flow to the brain. This improves its effectiveness.
All this means that we need to index chronological time to get to biological time. The passing of one chronological year has less of an impact on age. However there are other “times”
Our Bodies May be on Earth but our Heads are on Mars
Beyond the age of twenty-five, if we are asked “How old do you feel?” we invariably give a younger age than our chronological age. Third Age consumers across the world feel younger than their actual age. How much younger varies not only by chronological age but by country. The Danes of a given age feel younger than comparable Americans.
The data for Denmark is typical of most countries. At all ages over forty, less than five percent of people say they feel older than their birth certificate age. (Until the very end of their lives). There is a constant group of around thirty percent who feel their age. The balance, of close to seventy percent, claim to feel younger. They feel on average, twenty percent younger. A seventy-year-old in this group on average feels fifty-six years old and an eighty-year-old, sixty-four. The overall average is the mix of the three groups: feel older; feel your age and feel younger. Across all Danes a seventy-year-old feels only fifty-nine. There are huge variations across individuals.
As our chronological age increases so does the age we feel. However, our chronological age and the age in our heads do not increase at the same rate. Our heads are on Mars time. It takes Mars six hundred and eighty-six days to circle the sun, so time goes more slowly. Ten years on earth would feel like five point four years on Mars. How old we feel increases approximately five point four years for every chronological decade. The average seventy-year-old may feel sixty. In the ten years it takes them to reach eighty, they will only change the age that they feel to just over sixty five.
Feeling younger is not just a “nice to have”. "Felt age” is a better predictor of the onset of many psychological and physiological diseases. It is however a two-way street and an illness can often make people feel older. Feeling older than your age is correlated negatively with life expectancy.
Time We Have Left
In the last Newsletter I introduced a different measure of time : Time We Have Left. Carstensen’s idea was that at some point mortality becomes real. Her “socioemotional selectivity theory” says that at that point we start to adjust our behaviour. We do this based on the time we feel we have left. We manage our lives to maximize positive emotional experiences. Life becomes too short to do anything else. The theory is more complex because it suggests that there is not a single point at which our motivation changes. Instead there is a progressive change as our life expectations age. Scales have been developed to measure not only the time we feel we have left, but our aspirations.
Which is the Best Time?
Last month in the Journal of Services Research two friends published an interesting study. They were looking at different measures of time. My friends asked a simple question. Which time is the better predictor of our behaviour? Is it our chronological age? Is it our “Felt Age”, the age that we feel inside? Is it the “time we think we have left”?
They asked respondents about a recent experience with their bank or their grocery store. They were trying to predicted a number of behaviours. Did people intend to switch suppliers (loyalty)? Would they recommend the bank or store (Word of Mouth)? Would they complain? They also measured the respondents perceptions of that experience. Finally they assessed their view of value for money.
The results are interesting. In terms of switching behaviour the “felt age” is a better predictor. This is consistent with the large car purchasing study in Newsletter #34. On all of the other measures the best predictor is the future time perspective: the time we think we have left.
I am not sure that I want focus on the time I have left. May be we should all just look on the "Bright Side of Life”?