A flood of medical advances has extended the lives of people in most wealthy countries. However, a new paper argues that talk of living forever, or even to 150, is highly improbable, and not consistent with the trends we have seen. Moreover, even if our lives are extended, we cannot assume the past extension of our health will continue along with them.

Two centuries ago, the average human lifespan was less than half of what it is today even in the richest countries, little better than what it had been in most eras since our species first evolved. The initial spectacular increase in life expectancy, first in a few wealthy countries but eventually spreading to most of the planet, was mainly the product of a decline in childhood diseases. Those who made it to adulthood early in the 20th century could not expect to live that much longer than their great grandparents, but they were much less likely to see their children or grandchildren die before them.

Despite the space anti-vaccine campaigns have made for the return of measles and whooping cough, infant mortality continues to decline as the programs that allowed this transformation reach into the poorest nations on Earth. However, in most of the world, further gains will have to come at the other end of life, among those aged over 60. Professor S. Jay Olshansky of the University of Illinois, Chicago, and co-authors argue in a new paper we shouldn’t expect too much.

As the focus of medical research turned from diseases of the young to those of the middle aged or elderly – and research budgets expanded – a lot of progress was made. The number of people living to 100 rose dramatically, even if you discount data from “blue zones” tainted by fraud. However, Olshansky and co-authors note, these sorts of improvements have slowed down in the parts of the world that received the benefits first. Further improvement has mostly come by the expansion of technologies more widely.

“Most people alive today at older ages are living on time that was manufactured by medicine,” Olshansky, said in a statement. “But these medical Band-Aids are producing fewer years of life even though they’re occurring at an accelerated pace, implying that the period of rapid increases in life expectancy is now documented to be over.”

Olshansky investigated the changes to life expectancy in the eight countries where it is currently the longest, as well as in Hong Kong and the United States. The debate the paper enters is not a new one, as the authors acknowledge, with the competing “limited lifestyle” and “radical lifespan extension” hypotheses having been going back and forward at least since 1990. Olshansky himself helped kick it off in that year. Partly for this reason, the authors chose the period 1990-2019 to study life expectancy changes in these countries.

They found that only Hong Kong and South Korea managed to gain three extra years of life per decade, as the radical lifespan extension hypothesis proposes. In Hong Kong’s case that was just from 1990-2000 thanks largely to a crackdown on tobacco, something hard to repeat.

Only Hong Kong showed an increase in the proportion of people living to 100 that might be considered exponential, another effect anticipated by proponents of radical lifespan extension. Elsewhere, the number of centenarians has risen more modestly. Most of the improvement has come in the form of people being more likely to survive their 60s or 70s, rather than plummeting death rates among those over 90.

Olshansky is not the first to notice that life expectancy in wealthy countries is not galloping ahead at the rate it used to. In fact, in the United States life expectancy has fallen. Nevertheless, there are still plenty of people selling dreams of near-eternal life, while others demand increases in retirement ages on the basis most of us will soon be living past 100. Not long ago, books and essays were being written about how those alive at the time represented the “last mortal generation”, that people born in the 21st century would never die. 

Instead, Olshansky and co-authors conclude current trends will not see more than 15 percent of women or 5 percent of men reach 100, at least in the current century. The authors calculate the reductions in annual mortality rates among the elderly required for living to 150 to become widespread and consider them implausible.

“Our result overturns the conventional wisdom that the natural longevity endowment for our species is somewhere on the horizon ahead of us – a life expectancy beyond where we are today,” Olshansky said. “Instead, it’s behind us – somewhere in the 30- to 60-year range. We’ve now proven that modern medicine is yielding incrementally smaller improvements in longevity even though medical advances are occurring at breakneck speed.”

That doesn’t mean progress has to stop. “This is a glass ceiling, not a brick wall,” Olshansky said. The recent shortening of life among white Americans was caused partially by COVID-19, but more by “deaths of despair” associated with increased suicides and use of addictive painkillers. The solutions to these may require different approaches to those applied to traditional killers, but that doesn’t mean medical research can’t play a role.

Nevertheless, the authors think the future of medicine is in improving the quality of life of the elderly, rather than simply helping them live longer.

The study is published in Nature Aging