Humanity is reaching the upper limit of life expectancy, according to a new study.
According to researchers who found that longevity gains are shrinking in countries with the longest-living populations, advances in medical technology and genetic testing – not to mention more people living to the age of 100 – are not translating into a significant increase in overall life expectancy.
“We need to recognize that there is a limit” and perhaps re-evaluate assumptions about when people should retire and how much money they will need to survive their lives, said S. Jay Olshansky, a researcher at the University of Illinois at Chicago who was the principal author of the book, a study published Monday by the journal Nature Aging.
Mark Hayward, a researcher at the University of Texas who was not involved in the study, called it “a valuable addition to the mortality literature.”
He agreed that we are “reaching a plateau” in life expectancy. It's always possible that some breakthrough could take survival to the next level, “but we don't have that right now,” Hayward said.
Life expectancy is the estimated average number of years that a child born in a given year is likely to live, assuming that the death rate during that time remains constant. It is one of the most important measures of global health, but it is also imperfect: it is a snapshot estimate that cannot account for deadly pandemics, miracle cures or other unforeseen events that could kill or save millions of people.
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In the new study, Olshansky and his partners examined life expectancy estimates from 1990 to 2019, based on a database administered by the Max Planck Institute for Demographic Research. The researchers focused on eight places in the world where people live the longest – Australia, France, Hong Kong, Italy, Japan, South Korea, Spain and Switzerland.
The United States isn't even in the top 40. But they were also included “because we live here” and because of bold previous estimates that U.S. life expectancy could rise dramatically this century, Olshansky said.
Scientists have found that women continue to live longer than men, and life expectancy continues to improve, although at a slower pace. In 1990, average progress was about 2 1/2 years per decade. In 2010 it was 1.5 years, and in the USA it was almost zero
The United States is more problematic because it is more affected by a range of problems that kill people before they reach old age, including drug overdoses, shootings, obesity and inequality that make it difficult for some people to get sufficient health care.
But in one calculation, researchers estimated what would happen at all nine sites if all deaths before age 50 were eliminated. Olshansky said the increase was only 1.5 years at best.
Eileen Crimmins, an expert in gerontology at the University of Southern California, said in an email that she agreed with the study's findings. She added: “For me personally, the most important issue is the dismal and deteriorating relative position of the United States.”
Why life expectancy may not increase forever
The study suggests there is a limit to how long most people can live, and we have already reached it, Olshansky said.
“We are squeezing less and less life out of life-extension technologies. And the reason is that aging becomes a hindrance,” he said.
It's common to hear about a person living to the age of 100 – a milestone reached by former US President Jimmy Carter last week. Olshansky said just over 2% of Americans reached 100 in 2019, compared with about 5% in Japan and 9% in Hong Kong.
Experts say the number of centenarians is likely to increase in the coming decades, but that's because of population growth. The percentage of people who live to be 100 will remain limited, and it is likely that in most countries less than 15% of women and 5% of men will live to that age, Olshansky said.
