Want to be a supercentenarian? The chances of reaching the ripe old age of 110 are within reach—if you survive the perilous 90s and make it to 105 when death rates level out, according to a new study.
Researchers tracked the death trajectories of nearly 4,000 residents of Italy who were 105 and older between 2009 and 2015 and found that the chances of survival for these longevity warriors plateaued once they made it past 105.
“Our data tell us that there is no fixed limit to the human lifespan yet in sight…”
The findings, which appear in Science, challenge previous research that claims the human lifespan has a final cut-off point. To date, the oldest human on record, Jeanne Calment of France, died in 1997 at age 122.
“Our data tell us that there is no fixed limit to the human lifespan yet in sight,” says senior author Kenneth Wachter, a professor emeritus of demography and statistics at the University of California, Berkeley. “Not only do we see mortality rates that stop getting worse with age, we see them getting slightly better over time.”
Specifically, the results show that people between the ages of 105 and 109, known as semi-supercentenarians, had a 50/50 chance of dying within the year and an expected further life span of 1.5 years. That life expectancy rate was projected to be the same for 110-year-olds, or supercentenarians, hence the plateau.
The trajectory for nonagenarians is less forgiving. For example, the study found that Italian women born in 1904 who reached age 90 had a 15 percent chance of dying within the next year, and six years, on average, to live. If they made it to 95, their odds of dying within a year increased to 24 percent and their life expectancy from that point on dropped to 3.7 years.
Overall, the researchers tracked the mortality rate of 3,836 Italians—supercentenarians and semi-supercentenarians—born between 1896 and 1910 using the latest data from the Italian National Institute of Statistics.
They credit the institute for reliably tracking extreme ages due to a national validation system that measures age at time of death to the nearest day: “These are the best data for extreme-age longevity yet assembled,” Wachter says.
As humans live into their 80s and 90s, mortality rates surge due to frailty and a higher risk of such ailments as heart disease, dementia, stroke, cancer, and pneumonia.
Extreme old age linked to new gene variants
Evolutionary demographers like Wachter and coauthor James Vaupel theorize that those who survive do so because of demographic selection and/or natural selection. Frail people tend to die earlier while robust people, or those who are genetically blessed, can live to extreme ages, they say.
Wachter notes that similar lifecycle patterns have been found in other species, such as flies and worms.
“What do we have in common with flies and worms?” he asks. “One thing at least: We are all products of evolution.”
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Coauthors are from Duke University, the Max Planck Institute for Demographic Research, Sapienza University of Rome, the Roma Tre University, the Italian National Institute of Statistics, the University of Southern Denmark, Duke University, and the Max Planck Institute for Demographic Research.
Source: UC Berkeley