Posted on 19 November 2021
Science fiction tends to have a rather bleak outlook when it comes to humanity’s ability to cure ageing. In Dune, lifespan is extended through consumption of the Spice Melange, a drug over which wars are fought and from which withdrawal is fatal. Many sci-fi universes include other forms of lifespan-boosting treatments, but these often come at some terrible cost – withering health, madness, or loss of one’s humanity.
It’s easy to understand why lifespan extension is depicted in this way – stories need sources of conflict and moral dilemma. What’s more puzzling to me are those fictional worlds that gloss over the idea of life extension. Perhaps the treatment is too rare or too inaccessible to have an impact on society, or perhaps it doesn’t even exist. Whether it be 200 years or 2000 years from now, it is assumed that humanity has made practically no progress in this regard. We have visited distant stars, formed interstellar governments, even learned to overcome the laws of physics – yet we still haven’t been able to overcome our own biology.
This pessimism about the future is a reflection of our own pessimism and apathy today. We are conditioned from childhood to accept that ageing and death are inevitable – facts of life that we should accept or even embrace. However, there’s a solid argument to be made that people born today will live considerably longer than their predecessors. Indeed, even the ability to extend lifespan indefinitely might not be as far off as you think. There is a small but respectable number of scientists who genuinely believe that we will reach longevity escape velocity (LEV) some time during this century, perhaps even within its first half. Longevity escape velocity is the point at which each year, medicine and/or technology advance enough to ‘de-age’ you by one year or more. This isn’t quite the same thing as immortality – even if you could stay 25 forever, you’d still have a (small) chance of dying from disease or fatal injury. It would, however, allow you to vastly outlive your ancestors, and to do so in good health.
Are these people delusional, or have we become too accepting of our own mortality, to the point that we instinctively refute the idea that we might live for thousands of years? Let’s discuss this possibility seriously: how likely is it that we can actually reach LEV within the lifetime of someone who is born today? In this first article, I will present the basic principal explaining why it is not unreasonable to hope for massive gains in life expectancy this century. In part 2, I will discuss some of the routes we might take to reach a longevity escape situation. In the final part, I will address some of the problems that might come about as a result of human ageing reversal.
Firstly, I hope we can agree on one thing: that we can (and eventually will) find a way to fully reverse or circumnavigate human ageing. As Richard Feynman pointed out, there is no law of physics nor biological mechanism to suggest that ageing and death are inevitable. Indeed, clonal organisms (which reproduce asexually to form genetically identical offspring) can already be considered immortal after a fashion. If there is no physical or biological law to enforce the ageing process, humans will surely find a way of reversing it eventually, assuming we don’t wipe ourselves out first. That’s still a far cry from claiming that humans born this century might live thousands of years, though. What possible reason do we have for even entertaining this idea?
There is nothing in biology yet found that indicates the inevitability of death. This suggests to me that it is not at all inevitable and that it is only a matter of time before biologists discover what it is that is causing us the trouble.-Richard Feynman, The Pleasure of Finding Things Out
When predicting the future, it is important to realise that human technological advancement is not linear, but exponential. Exponential growth is a concept you might be familiar with in the context of the COVID-19 pandemic. In linear growth, the value that is growing always increases at the same rate. For example, the hairs on the human head grow at a rate of roughly 6 inches a year. In exponential growth, the amount by which a value grows depends on the value itself. For example, a typical population of yeast doubles every 100 minutes or so, meaning the more yeast cells you already have, the faster the yeast population will increase. Human technology works on the same principal, because we use our technology to build more technology – just think of how many technologies are enhanced by computing, for example.
Above: Moore’s law is an example of exponential growth. It is the observation and projection that the number of transistors in an integrated circuit doubles roughly every 2 years.
When using intuition alone, humans are quite bad at predicting exponential growth. Take the following example: you begin with a piece of paper that is 0.1 millimetres thick. If you fold it once, it’s now 0.2mm thick. Fold it twice, 0.4mm. Assuming you could keep folding it forever, how many times would you need to fold the paper for its thickness to surpass the distance between the Earth and the Moon (about 384 000 km)? Well, after 21 folds, the paper would be about 210 meters thick. After another 21 folds, the paper would have reached the Moon, with around 55 000km to spare. After around 94 folds, the paper would be thicker than the observable universe.
Exponential growth is scarily deceptive, especially when it is working against us like in the case of COVID-19. After 21 folds, the thickness of the paper is only a tiny fraction of what is necessary to reach the Moon, yet in terms of fold number we are already half way there, as growth seems to suddenly explode. This point at which growth switches from deceptively slow to eye-wateringly fast is referred to as the ‘knee of the curve’. Humans are hopelessly inadequate when it comes to predicting exponential growth, because we intuitively tend to base our predictions on our recent experiences without noticing the exponential growth factor. ”There were 20 new COVID cases last week, so there will be 20 more this week” will be a familiar example of fatally flawed assessment of an exponential growth situation.
Human technology grows in much the same way: for the vast majority of human history, technology advanced at a snail’s pace, while in the last few centuries, there has been more technological progress than in the preceding few millennia. Similarly, over the following 100 years, we may experience over 1000 years of progress measured at today’s rate if the current exponential trend continues.
While it will be discussed in more detail in part 2, it’s worth briefly mentioning the importance of artificial intelligence at this point. When it comes to extending human lifespan, there is a lot riding on how rapidly AI technology advances over the coming decades and how effectively we use it. AI with equal or greater than human intelligence will probably exist within the first half of this century, and that’s a relatively conservative estimate compared to those of some computer scientists like Ray Kurzweil, who believes that this will happen by the end of this decade. Once such AI exists, we will have computers that can ‘think’ and solve problems in the same way as humans, but do so millions of times faster. We could then have them develop new technologies for us (including better AI) at an unprecedented pace. AI is possibly the most important ingredient to the exponential growth surprise factor, because it allows problems that seem insurmountable now (the complexity of the human brain comes to mind) to become trivial with machine intelligence.
Technological advancements that seem extremely distant now only appear so because we fail to account for exponential growth. Even if you still don’t believe that longevity escape velocity will be achieved this century, I hope you at least consider it more likely than you did when you started reading this article. This basic principal explains why it is reasonable to hope for longevity escape velocity within our lifetimes. In the next article, I will discuss how LEV might be achieved.
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