“We’ll be able to play tennis with our great-grandkids. People won’t spend the last years of their lives in nursing homes; they’ll be able to be productive members of society right up to the end.”
– Dr David Sinclair quoted in McMahon B. The new ageless. Weekend Australian Magazine 2015; 31 Jan: 13
RECENTLY I heard of a very eminent doctor who said that he did not need to prepare for dying because modern technology would soon be able to stop him dying until he was over 150. Pending the results of safety and efficacy drug trials, this seems unlikely.
However, it is appropriate to take just a few minutes to ponder the issue. It is immediately clear that there would be some very complex individual and communal repercussions – think social ecology – from a further doubling of the human life span.
With life expectancy in the developed and affluent world currently at about 80 years, and a generation time of 30 years, about 3.5 generations are alive at any one time. In other words, most newborns have parents and grandparents, and many also have great-grandparents. With a generation time of 20 years, a newborn may also have a great-great-grandparent.
If, hypothetically, we extended our life expectancy to 150 years and maintained a generation time of 30 years, a newborn would also have great-great- and great-great-great-grandparents. If the generation time was 20 years it would be great-great-great-great-great-great-grandparents, and all stops in between to a total of 504 individuals.
Until about 200 years ago we lived with high infant and childhood mortality, a life expectancy of about 65 if you had survived to the age of 10, and fewer elderly people.
This was the demographic reality within which our various cultures evolved. Community structure and values supported and were supported by small numbers of the elderly who were the repository of knowledge and accumulated wisdom. When the elderly (or anyone else) got sick they died quite quickly.
This holds true today for the few remaining hunter-gatherer communities and for communal mammals, such as killer whales and elephants. The vast bulk of the increase in life expectancy has been achieved by avoiding death in childhood. Any significant future gains will have to come from delaying death in the elderly.
So what would happen if we were to extend our life span to 150 years?
First, even if everyone (recognising that distributive justice would require access for all) remained healthy and active to 150 and then all rapidly died without prolonged morbidity, it would not be cultural business as usual; we would be creating a novel cultural challenge of great complexity.
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Without stringent controls on reproduction, doubling the average life span means doubling the population – think pharmacokinetics. If a living population is suddenly extended to eight, or even just six, generations living concurrently, quite some time would be necessary for a new steady state to develop.
In the short term, the world would become grossly overcrowded with even greater environmental repercussions, unless most young adults were stopped from having any children. They might object, and we would have to sacrifice our successors.
The new retirement age would be about 140 because the small minority within what we now consider to be the normal working-age group would not be willing or able to support their older relatives for 80 years.
Our longer lives would soon generate a surfeit of mature adults pottering around looking for meaning and something to do. There would be too few (if any) children to satisfy the doting instinct of their vast numbers of parents, grandparents, great-grandparents, and so on to great-great-great-great-great-great-grandparents.
The young would come to resent the elderly who blocked access to their future by occupying jobs and positions of authority, denied the “right” to reproduction, further degraded the environment and demanded that they play tennis.
I do not think that our evolved biology and culture, not to mention the economy, could deal with that level of challenge. As with all complex systems under severe stress, it is really just not possible to predict the outcome.
Of course, all this talk about living for 150 years is a self-indulgent distraction from the urgency of the challenges that we face. As we run into the wall that is our individual maximum life expectancy, we are expending large quantities of resources in an effort to squeeze a few drops out of the end of a life.
There is no dignity in the futile pursuit of time for its own sake and without consideration of quality. Our long-term biological interests are fulfilled by improving the future for our offspring, not by hoarding resources for ourselves.
Perhaps we can learn from the equanimity about death that we see in some of our dying patients to help our community to rediscover the universality of death and integrate that reality into the ways we lead our lives and experience our dying.
I think that my great-great-great-great-grandchild may have better things to do than play tennis with me, and anyway I may not be able to get time off work.
Associate Professor Will Cairns is a palliative medicine specialist in Townsville and author of the eBook Death rules: how death shapes life on Earth, and what it means for us.