Zee Media Bureau
New York: A new study has found that the absolute limit to human lifespan is no more than 125 years.
Scientists at Albert Einstein College of Medicine say they found no human has lived longer than 122 - the age reached by a Frenchwoman, Jeanne Calment, in 1997. She greatly outlived her husband, who died at 73, and achieved the longest documented lifespan of any person in history.
Since the 1970s, the maximum duration of life - the age to which the oldest people live -- has risen. But according to the researchers, this upward arc for maximal lifespan has a ceiling - and we have already touched it.
"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 author Jan Vijg, Professor at Einstein.
"But our data strongly suggest that it has already been attained and that this happened in the 1990s," Vijg noted.
For the study, Vijg and his colleagues analysed data from the Human Mortality Database, which compiles mortality and population data from more than 40 countries.
Since 1900, those countries generally show a decline in late-life mortality: The fraction of each birth cohort (i.e., people born in a particular year) who survive to old age (defined as 70 and up) increased with their calendar year of birth, pointing toward a continuing increase in average life expectancy.
But when the researchers looked at survival improvements since 1900 for people aged 100 and above, they found that gains in survival peaked at around 100 and then declined rapidly, regardless of the year people were born.
"This finding indicates diminishing gains in reducing late-life mortality and a possible limit to human lifespan," Vijg said.
The researchers then looked at "maximum reported age at death" data from the International Database on Longevity.
They focused on people verified as living to age 110 or older between 1968 and 2006 in the four countries - the US, France, Japan and the UK - with the largest number of long-lived individuals.
Age at death for these supercentenarians increased rapidly between the 1970s and early 1990s but reached a plateau around 1995 - further evidence for a lifespan limit.
This plateau, the researchers note, occurred close to 1997 - the year of death of 122-year-old French woman Jeanne Calment, who achieved the maximum documented lifespan of any person in history.
Using maximum-reported-age-at-death data, the Einstein researchers put the average maximum human life span at 115 years - a calculation allowing for record-oldest individuals occasionally living longer or shorter than 115 years.
Finally, the researchers calculated 125 years as the absolute limit of human lifespan.
Expressed another way, this means that the probability in a given year of seeing one person live to 125 anywhere in the world is less than 1 in 10,000.
Recently, an Indonesian man, Mbah Gotho, presented an identity card that says he was born on December 31, 1870. He claimed that he has crossed 145 years.
If proved correct, that could make him much older than the verified oldest person ever.
The study has been published online in the journal Nature.
(With IANS inputs)