A new study has suggested that radical life extension is all but impossible in this century [1], and it has made waves among people interested in living longer.
Out of steam?
A paper titled “Implausibility of radical life extension in humans in the twenty-first century” was destined to ignite controversy in the longevity community. Published in Nature Aging, it lists Jay Olshansky as its corresponding author, a renowned researcher who has been studying the populational dynamics of life expectancy for decades. We delved deeper into this study and reached several prominent community members for comments.
The 20th century saw average life expectancy at birth skyrocketing. For the first several decades, it was mostly fueled by lower mortality in infancy through middle adulthood due to advances in medicine and sanitation. In the later decades, as we got better in treating age-related diseases, the growth expanded to older cohorts.
At around the turn of the century, suggestions were made that this “radical life extension” of about 0.3 additional years of life expectancy per year will be sustained due to further advances in medicine [2]. Olshansky et al. claim that this is not nearly the case.
Currently nowhere near the target
By analyzing data from eight countries with the highest life expectancy (Australia, France, Italy, Japan, South Korea, Spain, Sweden, Switzerland), the US, and Hong Kong, the researchers found that improvements in life expectancy have markedly decelerated since 1990. While Hong Kong and South Korea seem to be doing slightly better, this does not change the overall picture.
Rather unsurprisingly, the US was a negative outlier, where increases in life expectancy stalled almost completely even before the COVID-19 pandemic. The researchers conclude that “radical life extension” (as defined by them) has not happened anywhere in the developed world since the late 20th century.
The next question they asked was whether we can plausibly expect a majority of people to live to 100 any time soon. In the analyzed populations, the average probability of people in current birth cohorts surviving to age 100 was 5.1% for women and 1.8% for men. The highest numbers were calculated for Hong Kong at 12.8% and 4.4%, respectively, which is very far from 50%.
Moreover, according to the paper, further gains in life expectancy necessitate accelerating decreases in mortality. For instance, even a one-year jump, from 88 to 89 in females and from 82 to 83 in males, would require lowering all-cause mortality rates in the respective sexes by 20.3% and 9.5%. In order to reach a life expectancy of 110, we need the level of mortality that “would require the complete cure or elimination of most major causes of death that exist today.”
On a brighter side, the researchers found evidence of compression of mortality: more and more deaths occur in a “shorter window of time at the outer reaches of human survival.” In other words, we are seeing fewer “untimely” deaths, but the definition of “timely” has barely changed. “It has become progressively more difficult to increase life expectancy,” the researchers conclude. “Old-age mortality has not been declining since 1990 at a pace that is even close to the rate of improvement required to achieve radical life extension in this century.”
An important caveat
The evidence for this claim is strongly rooted in recent population data. According to Steven Austad of the University of Alabama at Birmingham, “it is a well-researched compelling piece about the recent past of life expectancy gains, showing they have slowed appreciably.” In 2000, Austad struck a famous bet with Olshansky that the first person to live to 150 was already born by that time.
“It’s consistent with a variety of prior evidence that ‘unmodified’ human lifespan appears to max out at about 120-130 years at the individual level and probably close to 100 years at the population level,” said another prominent aging researcher, Matt Kaeberlein. “Another way of thinking about it is that lifestyle and other approaches can add about two decades of lifespan, if we could get everyone to adopt a healthy lifestyle and live in a healthy environment.”
The critics’ main complaint is that though well-researched, the paper states the obvious: that we should not expect any more rapid gains in life expectancy unless breakthroughs in anti-aging medicine occur. The authors themselves say as much: “It is important to note that these limits do leave room for such advances in medicine (treating disease or targeting the underlying causes of aging and improved behavioral risk factors) that could further improve mortality at older ages (that is, these limits are not brick walls for longevity).”
“Geroscience is about prevention to me,” said Austad, “and the implicit message in the piece is that continuing traditional medicine, treating people when they get sick, instead of preventing disease and disability by targeting aging is a big mistake.”
Aubrey de Grey, head of LEV Foundation, while admitting the paper’s scientific merits, strikes a harsher tone: “This is yet another appalling example of a fundamental disconnect between the content of an article about future progress against aging and its title. The article provides, as have innumerable others for decades, solid evidence that both mean and maximum human longevity will only ever rise by more than a further decade if there are fundamental breakthroughs in medicine against aging. But the title declares that such breakthroughs are ‘implausible.’ No basis for such an assertion is given.”
Mark Hamalainen of the Longevity Biotech Fellowship, an organization ferociously advocating for extreme life extension, also has a problem with the title: “I think the title for the article should’ve been ‘Radical life-extension is implausible if we stick to an outdated research paradigm which under-funds aging biology, data collection, and novel intervention modalities.’ It correctly assesses what the status quo paradigm can achieve – but ignores the possibility of shaking that up. It doesn’t consider alternatives to the pharmaceutical model such as replacement or cryopreservation, or tool development for more advanced bioengineering.”
As mentioned earlier, the authors acknowledge that future scientific advances might help break this “glass ceiling” but note that it is impossible to ascertain their impact today. Therefore, what is the utility of this paper, other than sticking it to people who made some incorrect predictions decades ago? Forecasts of future dynamics in life expectancy, the authors argue, are not simply academic exercises. They are used by various stakeholders, such as governments and insurance companies, to chart the course forward, and hence must be realistic. Being clear-eyed about that might help society to prepare for the coming shifts in the age and health composition of the population.
The bet is still on
Like with any scientific paper, one can think of some nuances that were not discussed. For instance, more well-off subpopulations might be a better model for what current best practices in medicine and lifestyle can achieve. Making those best practices more widely available might bump the average lifespan up a notch.
In the US, already in 2014, the average lifespan for the top 1% of earners reached 89 years for women and 87 years for men: the gender gap essentially disappeared. The difference between the top 1% and the bottom 1% was 10 years for women and almost 15 years for men. In today’s England, it’s 7.7 and 9.4 years, respectively.
This study can be both a sobering reminder and a wake-up call for longevity scientists and enthusiasts. “Targeting biological aging is necessary, but not sufficient,” says Kaeberlein, “to significantly increase population lifespan beyond the likely limits identified here and in several prior studies. It is also the most effective way to improve healthspan for most people. This is where most of our biomedical resources should be going if keeping people healthy (rather than keeping them sick, which is largely what we do today) is the goal.”
What about Austad’s bet with Olshansky? “To me, this nicely done paper changes nothing about our bet.” Austad says. “We both agreed from the beginning that a geroscience breakthrough would have to happen (probably by mid 21st century) for anyone to live 150 years. I’m still optimistic that will happen. Jay, of course, is more skeptical. But then he is a demographer. I am a biologist, and biology is where the real action is.”
Literature
[1] Olshansky, S. J., Willcox, B. J., Demetrius, L., & Beltrán-Sánchez, H. (2024). Implausibility of radical life extension in humans in the twenty-first century. Nature Aging, 1-8.
[2] Oeppen, J., & Vaupel, J. W. (2002). Broken limits to life expectancy. Science, 296(5570), 1029-1031.
