The LEV ladder

Tam Hunt
6 min readFeb 22, 2020

What is “Longevity Escape Velocity” and how do we achieve it?

Chance of death has always been 100% historically. Yes, everyone who’s ever been born has died within about a hundred years or so of being born, which is the high end of life expectancy in developed nations today.

Based on this very consistent record of death throughout human history, it seems that talk about the potential to extend lifespans substantially doesn’t have much to go on.

But many serious thinkers are now in fact entertaining this possibility, based on real gains made in understanding how we age.

Are we now at the point where the chance of death could be ticking downwards by just a tiny amount, say 0.00001%? And could it continue to tick downwards over time?

This kind of thinking was inspired by the idea of “longevity escape velocity.” This is an analogy to the escape velocity required to break free from Earth’s gravity and into orbit. Longevity escape velocity (LEV) is all about achieving near-term breakthroughs that provide a few extra years of lifespan, which provides more time to develop additional breakthroughs and more years, etc.

If we achieve enough breakthroughs and enough added years, it’s obvious that we could — in theory — escape the Grim Reaper indefinitely. The “if” is very important, of course.

What, then, are the most likely rungs on the “LEV ladder” that will allow us to stay away from the Grim Reaper’s cold fingers indefinitely?

I had the pleasure of interviewing biogerontologist Aubrey de Grey recently on these issues. De Grey is perhaps the most well-known advocate of radical life extension, bursting on to the scene with his rigorous but accessible 2007 book, Ending Aging, and ever since becoming a fixture on the conference circuit and ubiquitous in discussions about longevity in scientific journals as well as in popular culture.

We conducted this interview by email in early 2020.

1) You wrote in your 2007 book, Ending Aging: The Rejuvenation Breakthroughs That Could Reverse Human Aging in Our Lifetime (p. 334): “We will almost certainly take centuries to reach the level of control over aging that we have over the aging of vintage cars — totally comprehensive, indefinite maintenance of full function — but because longevity escape velocity is not very fast, we will probably achieve something functionally equivalent within only a few decades from now, at the point where we have therapies giving middle-aged people thirty extra years of youthful life.” With the benefit of another 13 years of research under our belts, are you more or less optimistic about the specific timing for LEV?

The timing has slipped a bit: I think it was 2004 when I started making timeframe predictions, and back then I was looking at about 2029, whereas now I am saying 2036. But the good news is that the only thing I was overoptimistic about was funding (which I always cited as a caveat).

In the intervening 16 years, not a single thing has been discovered that constitutes bad news on the science side, i.e. a reason to believe that achieving LEV is harder than we previously thought. And because there is now an actual industry in the rejuvenation space, with investors writing much bigger checks than donors tend to write, that funding issue is progressively diminishing — which is reflected in the fact that my timeframe predictions have pretty much stopped slipping (I was already reckoning around 2036 five years ago). See my next answer too.

2) Do we have enough data about actual life extension trends in humans at this point to be able to extrapolate reasonable trends into the future for when LEV is likely to occur? How confident are you that 2036 will be the year we achieve LEV (similar to Ray Kurzweil, for example, predicting 2029 as the year for infamous “singularity” to be achieved in terms of computers achieving human-level intelligence)?

Let me answer those questions separately. On the first one: no data on actual life extension trends in humans can ever be a legitimate basis for extrapolation into more than the very near future, because by definition it consists of deaths that occurred in the absence of therapies that don’t yet exist. So, no, not only do we not have enough such data, we never will or could.

On the second one: I do indeed name a specific year, which is currently 2036 — but, of course, I am a lot more emphatic than Ray tends to be that this is the year by which I believe we have a 50% chance of reaching LEV. The other caveat that I always emphasise is that this prediction is based on the assumption that funding for the relevant research will not be rate-limiting — which is getting closer to being true these days, with the emergence and growth of the rejuvenation biotech industry, but is still not entirely true.

3) Have you or Chris Phoenix followed up on your 2007 co-authored
Age paper regarding predictions for life extension effects from possible interventions?

No, but I’m sad about that. Chris was entirely new to the area back then and he ascended an extremely steep learning curve, producing a really wonderful piece of work. I think there is plenty of potential for taking it further.

4) Does the
recent debate about Jeanne Calment’s actual age at death impact debates about the timing of LEV?

Not in the slightest.

5) What do you see as the most likely therapies for achieving the first set of beyond-normal lifespan longevity improvements (as opposed to diet, sanitation, disease prevention, etc., which have achieved historical life extension improvements)?

It won’t happen with just one therapy. Damage repair is inescapably a divide-and-conquer approach, where we fix different types of damage with different therapies — and where we can’t leave anything big out, because each of the major types of damage can kill you on its own, pretty much on schedule, however well we fix all the others. (This is a slight oversimplification, because there is certainly cross-talk between the types of damage, such that fixing one will slightly restore the body’s natural ability to retard the accumulation of others — but the magnitude of that cross-talk is small enough that my answer is solid to a reasonably good approximation.)

6) What areas of research today offer the most “bang for the buck” in terms of getting us to LEV? That is, it seems logical under the LEV framework that we should focus on approaches that could achieve the largest potential life extension in the near-term, and then in a phased manner focus on the tougher nuts later. Do we know enough at this point to make these kind of determinations?

Since no one therapy will get us even an appreciable distance closer to LEV, the bang needs to be measured in a different way — and there are two such ways. One is the extent to which the therapy would, on its own, be beneficial not to aging but to this or that early-onset disease arising (often congenitally) from the unusually rapid accumulation of the relevant type of damage. That’s the fast track to (a) showing that the therapy really works in humans and not only mice, and (b) making money out of it that repays the research investment.

Luckily, though, actually this metric doesn’t really rank the major future therapies (i.e. research areas): they all have their early-onset diseases to aim at. So the metric that DOES lead to a prioritisation is the other one: simply, how far along the research already is. And as you can probably already see, that metric is the inverse of what one might initially guess. The ones that will in reality give the best bang for the buck are the ones that are least far along, simply because they are just as valuable as the others in the long run but they currently need fewer bucks!

7. So where do these considerations leave us in terms of your projections for the major interventions/therapies that are most likely to be the first, second, third rungs on the “LEV ladder” to actual escape velocity?

Again: there really aren’t any “rungs” per se, because this isn’t a step-by-step crusade. We are developing an arsenal of tools and techniques, some of which (such as CRISPR, and induced pluripotency) are applicable across quite a wide range of damage-repair research areas, and some of which (such as enzymatic degradation of waste products) are more like strategies for discovering tools. The actual therapies to address a particular health problem, such as cancer, will typically combine a number of such tools.



Tam Hunt

Public policy, green energy, climate change, technology, law, philosophy, biology, evolution, physics, cosmology, foreign policy, futurism, spirituality