In April of this year I attended a conference in London sponsored by the MacArthur Foundation. I’ve been a member of their MacArthur Research Network on an Aging Society for the last twelve years – we hold these meetings often. One of my colleagues in the Network gave a presentation with a headline claiming that we need to plan for a 100-year lifespan.
I was more than a bit surprised at this declaration given that my colleague knew quite well that I’ve stated in multiple settings for the last 32 years, why this is just not going to happen. The Research Network is well aware of my reasoning and has supported my effort over the years to suppress exaggeration, embellishment, and misrepresentation when it comes to the future of human longevity. I was therefore surprised to see it from one of my colleagues that should have known better.
At the end of her presentation, I raised my hand and said to my colleague: “I assume you’re using the ‘100-year lifespan’ concept as a metaphor for the dramatic rise in the number of people that will reach older ages by mid-century.” Both the presenter and the meeting chair responded by stating “we realize that a 100-year life expectancy for a population is unlikely; and there is disagreement on this issue; but the real reason we’re using this phrase is because it is good for marketing.”
To which I responded, “I understand the use of this term for marketing purposes only – that makes sense, just so no one at the Network provides harmful advice to people that are planning for retirement, suggesting they should be planning for a 100-year lifespan. Telling a 60-year old, for example, to plan to live to 100 when there is only a 3.7% chance of surviving that long – would be harmful financial planning advice.” The Network agreed.
Since then I did a podcast interview on this topic, so this Newsletter is going to be brief. I’m providing you a link to that podcast so you can listen for yourself on why a 100-year life expectancy for a national population is not going to happen in this century.
Let me be clear – I’m not saying there’s a low chance it’ll happen in this century; I’m stating categorically that it will not (in fact, cannot) happen – and even if it was happening – we would have no way of knowing it.
Provided below is a summary of my points. If anyone listening to this podcast has any questions, do not hesitate to contact me personally.
- There will be a dramatic rise in the number of people living past ages 90 and 100 in this century. That is a demographic certainty. This rising prevalence of older people is a byproduct of larger birth cohorts from the 20th century – it is minimally influenced by lower death rates at older ages or treatments for diseases of aging.
- Radical life extension has already occurred – this is known as the First Longevity Revolution and it occurred during the last 170 years.
- However, this increase in the prevalence of older people will have almost no influence on the actuarial metric of life expectancy at birth (or at older ages) for national populations.
- The metric of life expectancy operates much like a Richter scale used to measure the strength of an earthquake – the scale of operation is exponential, not arithmetic.
- This means the higher life expectancy rises, the more difficult it is to raise it further. This does not mean that death rates cannot decline at older ages – they probably will. It just means that such declines will have a diminishing influence on the rise in life expectancy at birth and older ages.
- Once life expectancy for a national population reaches 85 years, the magnitude of the decline in death rates required to move this metric further north, becomes increasingly more difficult.
- Generating the mortality declines required to raise life expectancy at birth for a national population to 100 years at birth is both mathematically and biologically implausible.
- Anyone claiming that life expectancy at birth for a national population will rise to 100 years or higher; or that half the babies born today will live to 100; or that they know lifespan will exceed 122 years, is making up their numbers out of thin air. These are all positions of advocacy – they are not based on science.
- Even if a breakthrough in aging science allows us to slow biological aging – and I’m optimistic this will happen – it is virtually impossible to empirically test the influence of such an intervention on the future rise in lifespan or life expectancy. The reason? It would take more than half a century to test this hypothesis.
- To be crystal clear – claims of radical life extension for the future cannot be scientifically tested or verified using the tools of science.