While immortality isn’t in the cards and radical life extension for countries are highly implausible for reasons I’ve explained in previous newsletters, there is an argument presented by a friend of mine – Aubrey de Grey (the former head of an organization called SENS) suggesting that the first person to live 1,000 years has already been born. He’s not suggesting that someone alive today is 1,000 years old; rather, he suggests someone alive today will be alive in 1,000 years. According to Aubrey and proponents of this view, aging science will eventually manufacture survival time faster than the biological time that is ticking in us all as a byproduct of being alive.
This should sound familiar – Prudential echoed a similar argument (based on Aubrey’s reasoning) in a billboard ad that the first person to live to 150 has already been born. This advertisement (to the right) was designed to scare people into buying one of Prudential’s retirement products.
In case you don’t want to take the time to read The Paradox of Immortality we published a decade ago, I’m going to summarize the key points below. To our clients in the life settlement arena, if you’re concerned about right tail survival risk linked to these arguments for radical life extension, the paragraphs below should offer you some level of comfort. If you’re betting on profiting from radical life extension occurring in your lifetime; well, I’m sorry, but you made a bad bet.
Zeno’s Paradox of Immortality
S. Jay Olshansky and Bruce A. Carnes
Source: Olshansky SJ, Carnes BA. Zeno’s Paradox of Immortality. Gerontology. 2013;59(1):85-92. doi: 10.1159/000341225. Epub 2012 Aug 15. PMID: 22906806.
Scientists who speculate on the future of human longevity have a broad range of views ranging from the promise of immortality, to radical life extension, to declines in life expectancy. Among those who contend that radical life extension is already here, or on the horizon, or immortality is forthcoming, elements of their reasoning appear surprisingly close, if not identical, to a famous mathematical paradox posed by the ancient Greek mathematician Zeno.
Zeno of Elea, a Greek philosopher born in 450 BC, was famous for posing paradoxes that challenged mathematicians’ view of the world. One paradox was known as The Achilles. The appealing logic behind The Achilles paradox, just as with all of Zeno’s paradoxes, is that on the surface it sounds like a reasonable argument. After all, if one can explain through lucid reasoning and mathematics that halving the distance between two objects can occur indefinitely within a given time frame for an object in motion, then it is understandable why some would conclude that the fast will never outrun the slow, and an arrow shot at a tree will never meet its target.
Zeno fools us into believing that space and time together can be divided into an infinite number of smaller pieces when applied to the action of moving objects – giving us the false impression that space is shrinking and time is slowing down. Of course, if Zeno was right, all movement would be impossible. The resolution to Zeno’s paradox is that adding up an infinite number of small distances does in fact yield the finite distance that has to be traveled, which is the reason why the fast do outrun the slow and an arrow does reach its target. The problem is not so much with Zeno’s mathematics, but the fact that space, time and moving objects do not operate this way.
Scientists who speculate on the future of human longevity have generated a broad range of views from the promise of immortality to anticipated future declines in life expectancy. Among those who contend that steady incremental increases in life expectancy will continue through the rest of this century, or that radical life extension is already here or on the horizon, four unique arguments have formed. Elements of their reasoning appear surprisingly close, if not identical, to Zeno’s paradox.
The Paradox of Immortality and the rationale behind it seem reasonable at first. Who could argue with the premise that just one more day of life is possible at any age, even if achieved through technologies that can only be dreamed of today?
The main problem with this logic in the modern era of long-lived people is that it requires extending the lives of people who have already survived to later ages (manufacturing survival time) at a faster pace than the lives of infants were extended in the past. For example, a female infant born in the UK in 2009 had a life expectancy of approximately 82 years, which means a female baby whose life is saved by medical technology has the potential to survive 82 years. However, saving the life of an 82-year-old woman today manufactures only a small amount of survival time (frequently months, sometimes years, but rarely decades). Increasing the life expectancy of older people in the future at a much faster pace than was achieved for younger people in the past requires increasingly larger (nonlinear) reductions in death rates that are well beyond anything ever achieved in humans at any age. Indeed, almost all future declines in death will have to occur within older cohorts in order to achieve even linear increases in life expectancy, and this progress will have to occur during a time when cures for most major fatal diseases could not accomplish this feat, and when the health status of younger and older generations is already documented to be in jeopardy.
The mathematics behind the Paradox of Immortality may appear elegant, but its predictions of immortality or radical life extension require unprecedented and unrealistic assumptions about how the biology of an organism is altered by the passage of time. As such, linear forecasts of life expectancy, because of their requirement of accelerating reductions in old-age mortality against a backdrop of currently unyielding biological consequences of aging, are likely to generate dramatic overestimates of human longevity – especially if the forecasts extend for more than one or two decades.
The fundamental error in the Paradox of Achilles was the assumption that time and space could be halved indefinitely for a moving object, thus making it impossible to do something as simple as crossing the street. The essential error in the Paradox of Immortality is the belief that because there are no genetic programs for aging and death, that evolution does not measure time and therefore, we can forever add one more day of life; we can forever repair the damage that accumulates in our bodies – eventually with near perfection; we can forever build bridges to immortality, and we can assume that death rates for increasingly older generations will decline in the future at an accelerating pace.
Evolution does in fact measure time; it measures ‘essential lifespan’, the longevity window of survival time needed to achieve Darwinian fitness. The biological events within this window – growth, development and maturation – and their temporal kinetics are under rigorous genetic control. Thus, essential lifespan is partially heritable. Survival beyond the essential lifespan; however, is not genetically orchestrated; there is no biological guarantee or even a need of one for extended lifespan or extreme longevity. The survival probabilities for extended lifespan are determined by an as yet unknown mixture of genes, behavior choices, environment and luck received and/or experienced within the essential lifespan.
Proponents of radical life extension are missing these proximate factors because they are looking in the wrong direction for answers to the question about whether limits on the lifespan of individuals and the life expectancy of populations exist – their gaze is exclusively focused only on the currently visible and a projected future lifespan horizon. Until they realize the biological answers to longevity limits and causes of aging are behind rather than in front of us, their visions for the future course of human longevity and life expectancy will continue to violate biological realities.
In the hypothetical race between Achilles and a tortoise, the slower can never be overtaken by the faster because the underlying assumptions about space, time and moving objects are false. In the Paradox of Immortality, radical life extension and immortal life sound plausible only because the underlying assumptions about biological time, and the forces that influence it, are either exaggerated or ignored. Immortality and eternal youth will remain wishful pursuits lacking scientific credibility and biological plausibility. There is, however, every reason to believe that progress in reducing avoidable mortality at middle and older ages will continue. Furthermore, modern science has made progress in understanding the biological determinants of longevity and aging with the intent of eventually using that knowledge to improve quality of life by extending the period of healthy life.