Breaking the Ceiling on the Current Maximum Human Lifespan

There has been some discussion of late in the scientific community regarding whether or not there is a maximum human life span, whether that concept is even meaningful, and the scope of improvement in human life expectancy that could be plausibly achieved in the near future. The present round of debate was kicked off by a paper published this time last year in which Jan Vijg's team made a pessimistic argument for a ceiling on human life span based on recent historical data - that the current gentle upward trend in human life expectancy will hit a limit. Since it can take a year to assemble a paper and get it through the peer review process, some of the in-depth responses to this paper are now arriving, such as the one I'll point out here.

Is there a limit to human life span? It is fairly obvious that the answer is both yes and no. It is "yes" in the sense that we don't observe anyone living much past 120, so while aging is the sum of all intrinsic biological processes that increase mortality over time, and whether or not death strikes in any given minute is a roll of the dice, eventually the mortality rate is so high that no-one remains lucky enough to live through it for long. That is in effect a limit. On the other hand, the answer is "no" in the sense that we know what these biological processes are, and modern biotechnology will soon enough build the means to repair and reverse the cell and tissue damage that causes aging and all of its consequences. As soon as any specific form of damage can be reliably repaired, then it will no longer act to increase mortality to lifespan-limiting levels, and people will live longer as a result. The prior limit will be pushed out, and a new limit established.

The present upward trend in life expectancy, about one year every decade for remaining life expectancy at 60, is caused by some mix of (a) better lifestyle choices over time and (b) accidental effects on very late life mortality arising from improvements in medical technology. These modest gains have to be accidental since over the past century next to no-one was deliberately trying to treat the causes of aging as a way to extend healthy life. The research and medical communities have certainly been trying to patch over the sort of age-related disease that kills most people somewhere in the age range of 60 to 90, with limited success. There is, however, no necessary reason for those efforts to correlate well with mortality rates in the tiny remaining cohort who survive into their 110s, most of whom evaded the full-blown age-related diseases that killed their peers decades before that age.

A fair amount of the discussion among scientists is focused around whether or not we can keep on doing whatever it is we've been doing, and see human life span continue to increase at much the same rate, essentially without limit. From my point of view, this is a somewhat pointless activity, as the research community will deploy rejuvenation therapies over the next few decades that will completely change the landscape. What happened as a result of the last fifty years of medical progress has absolutely no relevance to what will happen over the next fifty years of medical progress. In the past, researchers were not attempting to treat aging as a medical condition, and nor were they deliberately targeting mechanisms and causes of aging with that in mind. Now and going forward, they are. The difference will be night and day.

The authors of this paper are more concerned with whether or not animal data on the numerous methods of altering metabolism - those that have been demonstrated to somewhat slow the aging process - can be related to human data from the incidental past trend in life expectancy. They find that there are similarities at the high level. I don't know that this is any better than arguing from first principles as I did above, but it is certainly a great deal more work. The methods of slowing aging used to date, such as calorie restriction and pharmaceuticals intended to recreate some of the beneficial reaction to calorie restriction, are largely known to have much smaller effects on human life span than they do in mice - where they are reliable, and many are not all that reliable. I don't think that this area of research will contribute important gains to human life span in comparison to biotechnologies that repair accumulated cell and tissue damage, such as the rejuvenation therapies of the SENS research programs. So again it is a question mark as to what use the existing data from the past is to us when the best forms of future development will take an entirely different approach.

May You Live Until 120? Why Stop There, Ask Israeli Researchers

Israeli scientists are convinced the maximum life span can be increased to 140 years or more, if science treats not only diseases but also specifically tackles the aging processes. That's quite a boast, given that the longest confirmed life span so far is 122 years. As the means of intervening with and holding back the ravages of age increase, scientists are now asking whether our natural genetic makeup is actually limited to a maximum life span of 115 to 120 years, or whether this limit can be breached. As you might expect, the scientific community is home to a lively debate on the subject. Other scientists are convinced that developing ways of delaying the aging process is only a matter of time, and that mankind must not accept 120 years as a limit.

Haim Cohen, head of the Molecular Mechanism of Aging Laboratory at Bar-Ilan University, is one of those who believes the maximum life span can be increased by 30 percent and eventually cross the 140-year threshold (compared to 115 to 120 years today). "In the past century we've experienced a dramatic increase in human life expectancy. In the past 60 years, life expectancy at birth has risen by an average of 72 percent. However, the maximum life expectancy has risen by only 8 percent. In the study, we examined whether the minor increase in maximal life expectancy means humanity has reached its maximum potential. The average rise in life expectancy stemmed mainly from medical solutions dealing directly with disease symptoms, and that increased the number of people who lived to a more advanced age."

Until 100 years ago, dying of old age was a privilege. The new study shows that in 1900, only 30 percent of all deaths were related to age or age-related diseases, while more than half were caused by infections. From the 1950s onward, the picture changed dramatically, as infections became curable and some of the terminal diseases turned into chronic ones. Today, more than 80 percent of deaths are related to diseases that occur mostly among the elderly. These factors certainly contributed to extending the overall life expectancy, but why is that barely reflected in the maximum life expectancy? Cohen and his colleagues say it stems from the approach that has characterized medicine. "The changes in life expectancy have so far stemmed from medical treatments developed in response to various illnesses - but there was no intervention in the basic aging mechanisms. What will happen when we deal directly with those biological mechanisms and metabolic processes responsible for aging?"

To examine whether intervention in the aging processes will affect life expectancy, Cohen and his team gathered and analyzed all the studies made in the last 20 years ("There are hundreds of them," he noted). In them, scientists succeeded in delaying the aging of organisms such as fungi, worms, flies, mice, rats and even monkeys. "We found something interesting in all of them: The increase in the maximum age was almost identical to the rise in the average or median age, reaching up to 30 percent." Cohen believes the findings indicate that focusing on the biological and genetic causes of aging will allow for a further leap in maximal life expectancy in the future. "Aging is a natural biological process whose basic characteristic is decreased functioning. Though the aging process looks different in various organisms, it is based on very similar mechanisms."

Breaking the Ceiling of Human Maximal Lifespan

While average human life expectancy has increased dramatically in the last century, the maximum lifespan has only modestly increased. These observations prompted the notion that human lifespan might have reached its maximal natural limit of ~115 years. To evaluate this hypothesis, we conducted a systematic analysis of all-cause human mortality throughout the 20th century. Our analyses revealed that, once cause of death is accounted for, there is a proportional increase in both median age of death and maximum lifespan.

To examine whether pathway targeted aging interventions affected both median and maximum lifespan, we analyzed hundreds of interventions performed in multiple organisms (yeast, worms, flies, and rodents). Three criteria: median, maximum, and last survivor lifespans were all significantly extended, and to a similar extent. Altogether, these findings suggest that targeting the biological/genetic causes of aging can allow breaking the currently observed ceiling of human maximal lifespan.

Comments

@Reason,
>The prior limit will be pushed out, and a new limit established
Since rejuvenation biotechnology (as we hope) will rejuvenate us actually, there will be no new limit in biological sense. Of course, before we fully implement SENS 1.0 panel such single components as senolytics or glucosepane breakers will prolong health span, and may slightly prolong *average* life span. Hovewer, the question will they prolong *maximum* life span is open. I hope we will get full SENS 1.0 panel before we can answer.

Posted by: Ariel at November 24th, 2017 6:49 PM

I have always considered approaching life by simultaneously being optimistic and energetic/ productive towards that positive end -and- being rational and exhaustively analytical of worst-case/negative case-set. This means contributing to ideas that are self-enhancing and society-positive (however these are defined-but I think many here get the gist). Of course this also means a lot of navel-gazing, as it were, due to insufficient facts -and- the inevitable considering of the trade-offs and divergent paths that these considerations create:
Ageing amelioration/ prevention is an excellent way to exercise this.
Maximum life-span versus maximum health-span: Would you rather live to 180 with full knowledge of your surroundings and the ability to communicate your goals and thoughts but NOT be in 30s-ish health and be subject to some fragility (say the inability to drive or travel since you were 90) -or- live to 120 in 30s-ish health and then drop dead the next year - which is the greater degree of life success? why consider this? why not just say each is unacceptable and flagrantly state that a path that does not lead to 180 (and more) in 30s-ish health is the only one worth considering? because it is entirely reasonable to believe that there will be a 'branching' of resources, vision, and demand. What if, out of the pot of millions of dollars of resources available that clinical approaches to each differ enough that there is a split? - because, hey, there are people out there, ageing amelioration 'consumers' out there (who are underwriting this work), who will choose one or the other being reasonably confident that the ideal of 180 in 30s-ish health is out of range and that there is a need to choose one or the other - and the choosing of range of treatments (perhaps) is mutually exclusive? which leads to my fundamental belief that the 'act' of offering the two choices (or more) necessarily attracts more consumers thus increasing the size of the 'ageing amelioration' pie than it otherwise would be by offering the one-choice only: 'live forever at 30s-ish health'. I say this because, at this stage 'the name of the game' is attracting resources, which is by extension: consumers, which means offering compelling choices, which are reasonable sounding 'steps' that incrementally improve people's perception of what is possible. And in my, not-so-humble, opinion is best accomplished by the positive-but-somewhat-science-savvy-salesperson/investor-capitalist NOT the very-science-savvy-zealot/activist. For the same reason that solving the hunger/disease/poverty problems in Africa will not be solved by the charities/compassion-driven/activists but by the investor/business-first/capitalists that see Africans as potential consumers/ workers/ entrepreneurs rather than poor and unfortunate who simply need a hand-out/plan to achieve a worthwhile life. Which of course leads to understanding the motivations and outcome-goals of the different groupings of these people: activist vs investor. It is difficult to see, but one can only presume the activist, in the Africa analogy for example, motivation as not being about 'helping' the African as much as it is about spreading a lifestyle of compassion (and minimizing capitalism (and lets be honest - opportunism)) with that hope (desperate in my opinion) that the 'life improvement' will be one in the same with the compassion provided - an abject failure, in my analysis. Whereas the investor simply wants to empower the African (in this analogy still) to 'be themselves' under the value system of the capitalist/opportunist with the understanding that there is a very real risk of creating the polluting/unequal/predatory environment that we have here in the West - which is still better than the current circumstances (IM(not)HO) and is meeting with much success under recent Chinese 'investment'. Which is why it makes me so sad to see this website is more of a science-charity than a science-investor platform. Because investor mindset puts the individual first and assumes society will benefit as a result (mixed opinions on this) rather than the activist mindset of saying what the society model should be and expecting the individual to 'conform' or 'support' in this case. Just my 2 cents.

Posted by: Jer at November 26th, 2017 10:12 AM

Important paper.

I've been looking at this field for almost 20 years now, and it is a great relief to see the common consensus continually being chipped away by new approaches and technology.

We have to keep pushing, we are getting close now. Once we can prove there is a chink in the armor of aging, this field will be unstoppable.

Posted by: Mark Borbely at November 27th, 2017 9:49 AM

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