Extending the length of human life has long held a natural fascination for us all. Arguably our earliest surviving work of literature, “The Epic of Gilgamesh”, dating back to 2100BC, tells of the search by the King of Uruk for the secret of eternal life.
Since the Industrial Revolution, we have seen lifespan increase dramatically, with life expectancy having increased at the rate of about two to three years every decade. That means that on average, each generation is living around six to nine years longer than their parents. That is an impressive rate of progress. But there is a growing excitement that we are on the verge of making even more dramatic progress in tackling the deep causes of ageing.
The oldest person ever to have lived was Jeanne Calment, who reached the impressive age of 122 years and 164 days. But some optimistic researchers such as Aubrey de Grey now argue that the first person to live to 500 has already been born.
It may be that 500 is not a plausible projection – and it certainly isn’t the infinity that Gilgamesh was searching for. But this line of research raises fundamental questions about what a mortal life looks like.
Science can pursue the miraculous discovery of how to increase the length of life. However, there is a crucial duality about time – it is both a natural phenomena and a social convention. Whatever physical laws determine our lifespan, or the length of the day, it is social convention that defines our stages of life, the length of the working day and the weekend.
So as we pursue a deeper understanding of longevity, we need to also investigate what changes society has to make that longer life a good life.
So how long will I live for?
As might be expected, there are fierce disagreements amongst demographers as to trends in life expectancy – so ferocious in some cases as to remind you that demography is literally a matter of life and death.
There are effectively three camps. The already mentioned “accelerators” argue that we are poised to see a dramatic increase in the rate at which life expectancy expands. Ray Kurzweil and Terry Grossman talk about the three bridges that will help us cross the divide to super-longevity: following best practice; the benefits that flow from mapping the human genome; and future developments in nanotechnology.
Disagreements exist even within this group as to what this means for life expectancy, but the general assumption is that the potential is there to leapfrog several decades past even Jeanne Calment’s age.
The second group, the “levellers”, argue that trend increases in life expectancy are over. They claim that most of the major historical gains in lifespan came through eliminating infant mortality and the diseases of middle age – and these have been almost fully exploited.
Further, they argue that there is a very real threat that the upwards trend will go into reverse, due to the diseases of prosperity such as obesity: we may even see declines in life expectancy.
The final camp (“extrapolators”) argue there is no sign at all of the trend slowing down, since we are now seeing improvements in survival rates for 70-, 80- and 90-year-olds. As a result, they believe life expectancy will continue to grow at its current impressive rate. Even allowing for a slowdown, this trend still leads to substantial future rises in longevity.
So what is actually happening? It may be the case that we have, barring future medical or technological breakthroughs, reached the maximum human lifespan: we are not seeing increases in the age at which the very oldest individuals die, which is why Jeanne Calment, who died in 1997, remains the oldest person ever to have lived.
Yet as survival rates improve for those below 100, more and more people will live for longer – and will further increase average life expectancy.
In the UK, for example, if we assume no further improvements (which the ONS does in its standard “period” measures of life expectancy) then life expectancy in 2014 was 83 and 79.3 for girls and boys respectively.
Allowing for further improvements, but at a diminished rate, yields a “cohort” measure of life expectancy of 93.2 and 90.4. Assuming the current improvements in longevity continue, you get 105 for girls and 102 for boys. That’s a lot of uncertainty to deal with in how you plan for the rest of your life.
Will everyone get to live to 100?
So far, we have focused on averages. But there are large and growing inequalities in life expectancy between rich and poor.
One recent study, based on more than a billion tax records, showed that the richest 1% of American men have a life expectancy 15 years more than the poorest 1% – and that since the millennium the richest have seen their life expectancy increase by three years, but the poorest barely at all.
Even more disturbing are the findings of Anne Case and Angus Deaton which showed that the mortality rate for whites aged 45 to 54 with no more than a high-school education increased by 134 deaths per 100,000 people from 1999 to 2014.
As society grapples with how to deal with increases in life expectancy, it also has to deal with these inequalities. Income inequality can be reduced by taking money from the rich and giving it to the poor. The same cannot be done for years of life.
What kind of lives will these be?
There is only one thing worse than Thomas Hobbes’s view of life as “nasty, brutish and short” – a life that is nasty, brutish and long.
There is a natural fear that living for longer means extending the period at the end of our life. If these extra years of life are not healthy ones, then growing longevity is an unwelcome gift.
The good news is that life expectancy and healthy life expectancy are both increasing. More troubling is whether they are increasing at the same rate. A comprehensive global study found that healthy life expectancy on average was growing slightly less than one for one with life expectancy.
In other words, the majority of those extra years of life are healthy – but not in their entirety. So years of disability are increasing marginally.
All of this is consistent with the fact that increasing numbers of individuals in their 80s and 90s are more capable of performing daily tasks of living than previous generations.
Better health and better technology both contribute to this – and understanding best practice in countries which have seen a compression in years of morbidity is clearly crucial.
What does it all mean?
Current scientific research may be about to dramatically increase maximum life expectancy. Doing so would represent an enormous intellectual breakthrough with few parallels.
However, there is much we already need to contend with from a social science perspective given the improvements in life expectancy already achieved.
In particular, we need to create policies and financial markets that deal with the enormous longevity risk individuals face – especially given that government estimates of average life expectancy vary by 20 years.
We need to focus medical research on how we maintain mental and physical fitness so we are able to be productive for longer to support out longer lives.
We need to focus on making we find ways of narrowing the gap between rich and poor in terms of lifespan.
Above all, we need to change the social and commercial practices that produced the three-stage life of education, work and retirement that emerged in the 20th century. That structure worked when life expectancy was 70 – but not if life expectancy is 100.
If we are to really benefit from this extra longevity, the social science of redesigning life is as crucial as the scientific research of extending it.
