Over the past 150 years, humanity has unleashed unimaginable energy by splitting atoms and developed machines that allow us to soar through the skies. But arguably, our species’ most profound change has been far more basic: People generally live a lot longer than they used to.
This trend has now substantially slowed in wealthier nations, which appear to be nearing a limit in life expectancy improvements from modern medicine, according to a new study.
Researchers looked back on data from 1990 to 2019 in the eight countries with the longest-lived populations as well as the United States and Hong Kong. Increases in life expectancy slowed in all of these populations, and the average proportions of women and men expected to survive to 100 were 5.1% and 1.8%, respectively, well below predictions made in other studies. When the authors modeled a scenario in which life expectancy reaches 110, they found that this would require curing most major causes of death today.
The study, published on Monday in the journal Nature Aging, argues that sizable additional increases in life expectancy aren’t likely unless researchers find a way to slow aging itself, with the authors declaring that “humanity’s battle for a long life has largely been accomplished.” That’s a message that stands in stark contrast to the rhetoric of some of the longevity field’s most vocal proponents, who’ve spoken about how lifestyle and diet changes can allow people to live as long as 150 to 180 years.
“What this paper will hopefully do is impose a reality check on the field,” said Eric Verdin, CEO of the Buck Institute for Research on Aging, who was not involved in the study. “Talking about things that are unattainable sells books, and it generates clicks, and it generates enthusiasm … but it also detracts from the serious work that can be done now.”
Global life expectancy has soared from 30 years in 1870 to 71 years in 2021, according to Our World in Data, an online scientific publication. The reasons for the increase are many, including vaccines, antibiotics, clean water, sanitation, and improvements in health care, particularly for young children.
During much of the 20th century, life expectancy increased at an unprecedented rate of three years per decade. If this rise were to continue through the 21st century, there’s almost no overstating its wide-ranging effects on our lives. Life insurance companies, the Social Security Administration, and Medicare would all be impacted, and a rise in longevity could reshape how we all plan our working and retirement years.
Jay Olshansky, a researcher at the University of Illinois Chicago who studies the limits of human longevity, has argued not just that this rise won’t continue, but that it can’t. In 1990, he published a provocative study in the journal Science predicting that increases in life expectancy would slow because treating individual diseases wouldn’t stop the aging process — the accumulation of damage to cells and tissues over time. In an interview with STAT, he likened this situation to the arcade game Whac-a-Mole.
This latest study is an effort to see whether recent data support that prediction. Olshansky, first author of the new paper, worked with colleagues to analyze countries with the longest-lived populations — Australia, France, Italy, Japan, South Korea, Spain, Sweden, and Switzerland — and the U.S. and Hong Kong using the Human Mortality Database, a repository with death and population statistics from developed countries. While this database has information from more recent years, the authors stopped at 2019 to exclude the known negative effect of the Covid-19 pandemic on life expectancy.
The researchers found that since 1990, hardly any of the populations studied saw a life expectancy increase of three years per decade, the rate needed for radical life extension — with the exceptions of Hong Kong during the 1990s and South Korea this century. In all cases, the rate of life expectancy increase dipped over time.
The authors then calculated how many people in these regions would likely live to 100 using life tables, which break down mortality rates by age. They predicted the highest rate of centenarians in Hong Kong, with 12.8% of women and 4.4% of men born in 2019 expected to reach 100. Some researchers have previously claimed that most babies born since 2000 in countries with long life expectancies will reach 100.
Increasing life expectancy will require progressively higher reductions in mortality. During the early 1900s, mortality reductions of around 4% were enough to boost life expectancy by a year. But now, increasing female life expectancy from 88 to 89 years would require a 20.3% reduction in mortality from all causes at all ages, the authors found, and increasing male life expectancy from 82 to 83 years would require a 9.5% reduction.
In a hypothetical scenario in which life expectancy reaches 110, the authors estimate that 1 in 4 women would live to at least 122 years. There’s only one person in history documented to have lived that long — Jeanne Calment, a French woman who passed away in 1997. We’re nowhere close to that becoming commonplace, said Olshansky.
“People could try and dispute this, but they can’t, because this is what the data tell us actually happened,” he said. “We made a very specific prediction that the rise would decelerate, even in the face of advances in medical technology. We now know the answer.”
To get a sense of the best-case current scenario, Olshansky and colleagues took the lowest death rates recorded in 2019 across the world in different age groups and created a composite life table. They found that life expectancy was around 89 years for women and 83 years for men, numbers that Olshansky said represent a soft limit on lifespan.
The authors note that lower- and middle-income countries may experience rapid rises in life expectancy this century, but these increases will largely come from public health benefits that have already happened in wealthier nations. Olshansky also noted that there will be more 100-year-olds in the future — especially beginning around 2046. But that is because of the fertility rise that led to the baby boom generation, not because the percentage of people who survive to 100 will shoot up.
Steven Austad, chair of aging research at the University of Alabama at Birmingham, said the findings underscore that many of the simplest and most obvious ways to increase life expectancy have already been addressed.
“I think the central claims are pretty ironclad,” said Austad. “I’m not so convinced about the predictions of the future.”
He and Olshansky have a standing bet about that future. In 2000, Austad told Scientific American that the first person who’d live to 150 had already been born. Olshansky disagreed, and the researchers agreed to each put $150 into an investment fund that will go to the winner. They’ve more recently doubled their wager.
“I’ve pretty much already won the bet,” Olshansky said. “But Steve will disagree.”
And he does. “I love Jay’s misguided optimism,” Austad told STAT.
The two men are good friends, and they agree on one thing: Neither will be around to collect the winnings in 2150. Olshansky is 70 and Austad is 78, and both expect the returns will go to their descendants.
Austad’s optimism is based on early-stage laboratory work demonstrating that it’s possible to extend the lifespans of mice. He noted that there are more than 60 clinical trials testing such therapies in people, and he figures that it’s only a matter of time before some of these strategies pan out.
Olshansky’s team is now planning to track changes in health span, the portion of life when people are in good health. There’s already some evidence to suggest that longer lives aren’t always healthier ones. A 2017 study found that, between 1990 and 2016, the number of years people lived with significant limitations from disease or injury grew on average from 8.2 years to 9.3 years worldwide.
His team is also interested in estimating how long people would live without the benefits of modern medicine to understand, as he puts it, how much time medicine and public health have “manufactured.”
“I see our current lives as a celebration of success in medicine and medical technology,” Olshansky said. “We really need to rejoice in what we’ve done.”
He stresses that there are plenty of concrete steps people can take to improve their individual odds of enjoying healthier lives. Olshansky applies that thinking to his own life. He exercises regularly, speaking with STAT about the recent study while on a morning walk. After receiving follow-up questions later that day, he said he’d reply after finishing an afternoon workout. He also wears hearing aids in light of evidence that doing so can reduce the risk of dementia.
“It’s not like I don’t know that winter is coming,” he said. “But there are so many things that we can do on a day-to-day basis to lower our risk and improve our health and quality of life, and that’s what I zero in on.”