9th July 2021
Study estimates longevity extremes by 2100
A new study by the University of Washington has used Bayesian population projections to forecast the world's longest-lived person by 2100.
The number of centenarians – people who live past the age of 100 – has been on the rise for decades. It now stands at 573,000 worldwide. This figure is expected to increase to over 19 million by the year 2100.
There are, however, far fewer "supercentenarians," people who live to age 110 or even longer. The oldest recognised person, Jeanne Calment of France, lived to the age of 122; the current oldest person is 118-year-old Kane Tanaka of Japan.
Such extreme longevity, according to new research by the University of Washington (UW), will continue to rise during the 21st century, and estimates show that a lifespan of 125 years, or even 130 years, is possible.
"People are fascinated by the extremes of humanity – whether it's travelling to the Moon, how fast someone can run in the Olympics, or even how long someone can live," said lead author Michael Pearce, a UW doctoral student in statistics. "With this work, we quantify how likely we believe it is that some individual will reach various extreme ages this century."
The new study, published in Demographic Research, uses statistical modelling to analyse extremes of lifespan. With ongoing research into aging, the prospects of future medical and scientific discoveries and the relatively small number of people to have verifiably reached 110 or older, experts have debated the possible limits of what is referred to as the maximum reported age at death. While some scientists argue that disease and basic cell deterioration lead to a natural limit on human lifespan, others maintain there is no cap, as evidenced by record-breaking supercentenarians.
Pearce and his colleague Adrian Raftery, Professor of Statistics and Sociology at UW, took a different approach. They asked what the longest individual human lifespan could be anywhere in the world by 2100. Using Bayesian statistics, a common tool in modern statistics, the researchers estimated that the world record of 122 years will "almost certainly" be broken, with a significant chance of at least one person reaching somewhere between 125 and 132. After the age of 132, the probability quickly declines to negligible levels. Based on the modelling, somebody born in 1958 or earlier could reach the age of 142 during the 21st century, although this is considered extremely unlikely (0.003%). The researchers found essentially zero probability for 143 or older.
To calculate the probability of living past 110 – and to what age – Raftery and Pearce used the most recent iteration of the International Database on Longevity, created by the Max Planck Institute for Demographic Research. This tracks supercentenarians from 10 European countries, along with Canada, Japan and the United States. They then created projections for the maximum reported age at death in all 13 countries from 2020 through 2100, using a Bayesian approach to estimate probability.
As it is, supercentenarians are outliers, and the chance of breaking the current age record increases only if the number of supercentenarians grows significantly. With a continually expanding global population, the odds are greatly improved. The world's population, currently 7.8 billion, is forecast to reach 10 billion by 2060 and almost 11 billion by 2100.
People who achieve extreme longevity are still rare enough that they represent a select population, Raftery said. Even with population growth and advances in healthcare, there is a flattening of the mortality rate after a certain age. In other words, someone who lives to be 110 has about the same probability of living another year as, say, someone who lives to 114, which is about one-half.
"It doesn't matter how old they are, once they reach 110, they still die at the same rate," said Raftery. "They've gotten past all the various things life throws at you, such as disease. They die for reasons that are somewhat independent of what affects younger people. This is a very select group of very robust people."
• Follow us on Twitter
• Follow us on Facebook
• Subscribe to us on YouTube