Research shows that the increase in life expectancy may have reached its limit

Over the past 150 years, humanity has unleashed unimaginable energy, splitting atoms and creating machines that allow us to soar through the skies. But perhaps the most profound change in our species has been much more fundamental: humans generally live much longer than they used to.

This trend has now slowed significantly in wealthier countries, which appear to be approaching the brink of improving life expectancy thanks to modern medicine, according to a new study.

The researchers analyzed data from 1990 to 2019 from eight countries with the longest-living populations, as well as the United States and Hong Kong. In all of these populations, the increase in life expectancy has slowed, and the average percentage of women and men who will live to 100 is 5.1% and 1.8%, respectively, well below predictions in other studies. When the authors developed a scenario in which life expectancy reached 110 years, they found that this would require curing most of the leading modern causes of death.

The study, published Monday in the journal Nature Aging, argues that a significant additional increase in life expectancy is unlikely unless researchers find a way to slow aging itself, with the authors declaring that “humanity’s fight for long life has largely ended.” ” .” This message stands in stark contrast to the rhetoric of some of the most vocal longevity advocates, who have talked about how lifestyle and dietary changes could allow people to live to 150 to 180 years.

“Hopefully this paper will impose some reality checks on the ground,” said Eric Verdin, CEO of the Buck Institute for Research on Aging, who was not involved in the study. “Talk about the unachievable sells books, generates clicks, and generates enthusiasm… but it also distracts from the serious work that can be done now.”

According to the online scientific publication Our World in Data, global life expectancy has increased from 30 years in 1870 to 71 years in 2021. The reasons for this increase are many, including vaccines, antibiotics, clean water, sanitation and improved health care, especially for young children.

For much of the 20th century, life expectancy increased at an unprecedented rate of three years per decade. If this growth were to continue throughout the 21st century, it is almost impossible to overestimate its wide-reaching impact on our lives. This would impact insurance companies, the Social Security Administration, and Medicare, and the increase in longevity could change the way we all plan our working years and retirement.

Jay Olshansky, a researcher at the University of Illinois at Chicago who studies the limits of human longevity, argues not only that this increase will not last, but that jargon. In 1990, he published a provocative study in the journal Science in which he predicted that the increase in life expectancy would slow because treatments for specific diseases would not stop the aging process – the accumulation of damage to cells and tissues over time. In an interview with STAT, he compared the situation to the arcade game Whac-a-Mole.

The aim of the latest study is to see whether the latest data confirms this 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 – as well as the United States and Hong Kong, using the Human Mortality Index Database, Repository death and population statistics of developed countries. Although the database contains information from recent years, the authors stopped at 2019 to exclude the known negative impact of the Covid-19 pandemic on life expectancy.

The researchers found that since 1990, almost none of the populations studied have seen an increase in life expectancy of three years per decade, the rate needed to dramatically extend lifespan – with the exception of Hong Kong in the 1990s and South Korea this century . In all cases, the rate of increase in life expectancy decreased over time.

The authors then calculated how many people in these regions would likely live to age 100 using life tables, which break down mortality rates by age. They predicted that the highest percentage of centenarians would be in Hong Kong, where 12.8% of women and 4.4% of men born in 2019 would reach the age of 100. Some researchers have previously claimed that most children born since 2000 in countries with long life expectancy will reach the age of 100.

Increasing life expectancy will require an increasingly greater reduction in mortality. In the early 20th century, a reduction in mortality of about 4% was enough to increase life expectancy by one year. But now, the authors found, increasing women’s life expectancy from 88 to 89 years would require a 20.3% reduction in all-cause mortality at all ages, and increasing men’s life expectancy from 82 to 83 years would require a 9.5% reduction. .

In a hypothetical scenario in which life expectancy reaches 110 years, the authors estimate that 1 in 4 women will live to be at least 122 years old. Only one person in history has survived this long – Jeanne Calment, a French woman who died in 1997. We are a long way from this becoming common, Olshansky said.

“People could try to question it, but they can’t because the data tells us that this actually happened,” he said. “We predicted very specifically that economic growth would slow down, even in the face of advances in medical technology. Now we know the answer.”

To get a current best-case scenario, Olshansky and colleagues took the lowest death rates reported in 2019 around the world across age groups and created a composite life table. They found that life expectancy is about 89 years for women and 83 years for men, numbers that Olshansky says represent a soft boundary for life expectancy.

The authors note that lower- and middle-income countries may see rapid increases in life expectancy this century, but that this increase will largely be driven by public health benefits that have already occurred in wealthier countries. Olshansky also noted that there will be more centenarians in the future – especially starting around 2046. However, this is because of the increase in fertility that has led to the baby boom generation, not because the percentage of people who live to 100 will skyrocket. up.

Steven Austad, director of aging research at the University of Alabama at Birmingham, said the findings highlight that many of the simplest and most obvious ways to increase life expectancy have already been addressed.

“I think the core claims are pretty ironclad,” Austad said. “I’m not that confident about the future projections.”

He and Olshansky made a bet about this future. In 2000, Austad told Scientific American that the first person to live to 150 had already been born. Olshansky disagreed, and the researchers agreed to each contribute $150 to an investment fund that would go to the winner. They recently doubled their bet.

“I basically already won the bet,” Olshansky said. “But Steve won’t agree with that.”

And he does it. “I love Jay’s misguided optimism,” Austad told STAT.

The two men are good friends and agree on one thing: neither of them will be able to collect their winnings in 2150. Olshansky is 70 and Austad is 78, and both expect the profits to go to their descendants.

Austad’s optimism is based on early lab work that has shown it is possible to extend the lifespan of mice. He noted that there have been more than 60 clinical trials testing such therapies in humans and believes it is only a matter of time before some of these strategies come to fruition.

Olshansky’s team now plans to track changes in health, the part of life in which people enjoy good health. There is already evidence to suggest that living longer does not always mean living healthier. A 2017 study found that between 1990 and 2016, the number of years people lived with significant limitations due to disease or injury increased from 8.2 years to 9.3 years on average worldwide.

His team is also interested in estimating human lifespan without the benefits of modern medicine to understand, as he put it, how much time medicine and public health have “produced.”

“I see our life today as a celebration of successes in medicine and medical technology,” Olshansky said. “We really have to be happy with what we have done.”

It highlights that there are many concrete steps people can take to increase their individual chances of living a healthier life. Olshansky applies this thinking to his life. He exercises regularly, talking to STAT about the latest study results during his morning walk. After receiving further questions later that day, he said he would respond after the afternoon training session. He also wears hearing aids in light of evidence that it may reduce the risk of dementia.

“It’s not that I don’t know winter is coming,” he said. “But there are many things we can do every day to reduce risk and improve health and quality of life, and that’s what I focus on.”