Though the average human lifespan has steadily increased in the past century thanks to improved healthcare among other factors, new research suggests that the oldest people on record have already reached our maximum life expectancy. The study – conducted at Albert Einstein College of Medicine – was published in the journal, Nature.
The average baby born in the US today will likely live until age 79. Compared to the year 1900, when those born were only expected to live to age 49, this represents a 30 year increase in life expectancy in just over a century. The maximum duration of life – measured as the age to which the oldest people on record have lived – has also seen growth since the 1970s. But the Einstein researchers say that this growth cannot continue, and has likely already plateaued.
“Demographers as well as biologists have contended there is no reason to think that the ongoing increase in maximum lifespan will end soon,” said senior study author Dr. Jan Vijg, professor and chair of genetics, the Lola and Saul Kramer Chair in Molecular Genetics, and professor of ophthalmology & visual sciences at Einstein. “But our data strongly suggest that it has already been attained and that this happened in the 1990s.”
Using data from the Human Mortality Database – a compilation of over 40 countries’ population and mortality data – those countries have seen a decrease in late-life mortality since 1990. This means that the percentage of people born each year who reach the age of 70 or higher has increased every birth cohort, suggesting that average life expectancy in those countries has continued to increase.
Conversely, survival improvements data from those over the age of 100 tells a different story. The researchers found that regardless of the birth cohort someone belonged to, survival gains reached their maximum around age 100, and then began to sharply decline after the year 1990.
“This finding indicates diminishing gains in reducing late-life mortality and a possible limit to human lifespan,” said Vijg. In studying the age at death of some of the oldest reported individuals recorded in the International Database on Longevity, the researchers focused their attention on people from the US, France, Japan and the UK, who lived to age 110 or older between 1968 and 2006. While age at death did increase until the 1990s, the data plateaued near the middle of the decade.
This plateau of maximum age at death adds further support to the researchers’ theory that the lifespan limit for humans may have already been reached. In 1997, Jeanne Calment become the first documented person in history to reach the age of 122.
Based on the available data, the researchers concluded that the average maximum human lifespan is 115 years, with a calculated 125 years as the oldest age a human could potentially live to see. According to Vijg and his colleagues, the likelihood of seeing anyone in the world live to the age of 125 in any given year is less than 1 in 10,000.
“Further progress against infectious and chronic diseases may continue boosting average life expectancy, but not maximum lifespan,” said Vijg. “While it’s conceivable that therapeutic breakthroughs might extend human longevity beyond the limits we’ve calculated, such advances would need to overwhelm the many genetic variants that appear to collectively determine the human lifespan. Perhaps resources now being spent to increase lifespan should instead go to lengthening healthspan—the duration of old age spent in good health.”