While human life expectancy has been rising for decades in most countries, the record for the longest-lived person hasn’t been increasing – but that might be about to change.
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| Older people who are alive today may have benefitted from advances in medicine after the second world war Maliutina Anna/Shutterstock |
Using a new way of analysing mortality records, figures from 19 high-income countries suggest that we haven’t yet approached the maximum human lifespan and could see the record start to rise in the next few decades. “We don’t appear to be approaching a maximum limit at the moment,” says the study’s lead researcher David McCarthy at the University of Georgia in Athens.
The longest-lived person in history is recorded as Jeanne Calment, who died aged 122, although there have been recent doubts about her authenticity.
Since Calment’s death in 1997, the record for the oldest living person has been held by people aged between 110 and 120 – and it hasn’t nudged upwards over time. This has led scientists such as Jan Vijg at the Albert Einstein College of Medicine in New York to conclude that there is probably a biological limit on the maximum human lifespan, which he puts at about 115 years old.
But the latest findings suggest that the maximum human lifespan will soon start rising as people born in the first few decades of the 20th century reach very old age.
McCarthy’s team came to this conclusion after studying the age at death of people in various countries in Europe, plus the US, Canada, Australia, New Zealand and Japan, taken from the Human Mortality Database, a record of global birth and death statistics.
The researchers looked at the age of death in groups of people who were born in the same year. Most previous studies have grouped people according to their year of death, but this can obscure trends because it merges people with different lifespans, says McCarthy.
Analysing by birth year found that in those groups born after about 1910, their risk of dying in any given year increased as they aged but to a lesser extent than those born earlier. This suggests that the world record for the longest-lived person will increase in the coming decades as surviving members of these cohorts reach advanced old age, says McCarthy.
For instance, someone born in 1910 hasn’t yet had the chance to reach 120 years, as they would only reach that age in the year 2030.
People in these birth cohorts have benefitted from improvements in medicine since the end of the second world war, says McCarthy. We can’t predict how long that trend might continue from this kind of study, he says.
Vijg, however, says that the analysis depends on an assumption – that the risk of death per year, which for most of our lives rises exponentially with age, starts to plateau after people reach about 105. That assumption isn’t universally accepted, he says.
But Kaare Christensen at the University of Southern Denmark says that there is good support from previous studies for this assumption. “A lot of these projects hinge on models that predict what will happen in the future,” he says. “The truth is nobody knows.”
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