Human lifespan may have a natural limit that is unlikely to be exceeded, suggests an analysis of global demographic data published online this week in Nature. The maximum age of death ever documented for humans is 122 years, and the odds that this record will be broken appear small.
Human life expectancy and maximum age at death has increased steadily throughout the 20th century, lending support for the notion that the duration of human life may not have an upper limit. However, this trend has slowed in recent decades and the rate of improvement in survivorship rapidly declines after 100 years of age.
Using data from the Human Mortality Database, Jan Vijg and colleagues show that the age with the greatest improvement in survival plateaued around 1980. The authors then focused on the maximum reported age at death in France, Japan, the United Kingdom and the United States, as reported in the International Database on Longevity. This analysis revealed that age at death plateaued close to the time of death of Jeanne Calment - the oldest person ever documented - in 1997. The authors suggest that this could represent a natural limit of human lifespan. Their model predicts that the likelihood of a person exceeding age 125 in any given year is less than 1 in 10,000.
“As the authors rightly point out, the idea of a ‘natural limit’ to life does not imply that such a limit is a direct byproduct of some genetically driven program that causes both ageing and death,” writes S. Jay Olshansky in an accompanying News & Views article. “…[I]t means that there is no fixed limit beyond which humans cannot live, but that there are nevertheless limits on the duration of life that are imposed by other genetically fixed life-history traits.”