Lifespan is the average duration of life in a given population.
Healthspan is the number of years the average person can expect to live free of illness.
We use the term lifespan in the same way as ‘life expectancy’. Some people refer to lifespan to indicate the maximum possible duration of life (e.g. in humans this is generally considered to be 120).
We do not use it in this sense.
So when we mention lifespan on this site, think of it as life expectancy as described in the opening line.
Those simple definitions are enough, we hope, to explain the two key aspects of this site’s purpose, which is to help you live longer and have more years of life in great health.
However, the actual numbers you may read or hear about from time to time can be very misleading and potentially unhelpful.
The problem is when someone tells you the ‘numbers’ what do they actually mean?
Averages create the ‘problem’
For example, we can throw these numbers at you – lifespan age 79, healthspan age 63. In most Western and ‘developed’ countries those numbers will be somewhere close to current official figures.
You now know that for a baby born today they can expect to live to age 79 on average and for 63 of those 79 years – probably the first 63 years – free of ill health, on average.
In that sentence above there are two innocuous-looking wordings which are anything but innocuous.
- Firstly, “born today” and secondly “on average” – For most readers, who are say, 53 today that lifespan/healthspan figure is meaningless. As you were born 53 years ago.
- Secondly, on average means that the estimate is based around whole populations.
But you are one person.
Your individual prospect, or your personal lifespan and healthspan, could be very different.
There are other problems with the publicly quoted figures. The idea that lifespan (in particular) for a baby born today is anything other than a good guess by statisticians is clearly ridiculous.
This is not to ridicule statisticians, who are working with the figures as best they can, but simply to emphasise that those figures could change for a whole variety of reasons.
There are 79 years for the figures to change.
On top of this, when it comes to healthspan, we have another issue – what do we mean by ill-health? It is very easy to define lifespan, because someone is either alive or dead. But ‘ill-health’ is far more subjective and certainly less clear cut.
There are many other factors which make the numbers unreliable or of limited use to an individual.
Yet, they do provide some use and value. That’s because they indicate, reliable, general trends. They will offer a good idea of what most people can expect in trending terms.
Lifespan and Healthspan figures are not changing in line with each other
And in this respect, and this is backed up by swathes of research, surveys and studies, the figures indicate that as of 2021, generally lifespan increases have slowed, the enormous acceleration through the 20th century of life expectancy (where lifespan pretty much doubled) has begun to slow and in some populations come to a halt or even gone into reverse.
Plus, and this is crucial, those historic increases in life expectancy have been accompanied by a much slower increase in healthspan.
In simple terms, the amount of years an average person can expect to spend in ILL-HEALTH has GONE UP.
The summary of this is as follows:
Lifespan and healthspan numbers are useful to indicate general population trends, but around these trends (and the average figures) is a very substantial distribution.
This means that any individual contemplating their own position has a challenge if they want to relate these figures to their own expectations.
This means, in turn, that individuals have to work hard to ascertain their own prospects and this is what we are aiming to help you do on this site.