The death of the world’s oldest person at the age of 118 has rekindled a debate that has divided scientists for centuries: is there a limit to how long a healthy person can live?
After French nun Lucile Randon died last week, Spanish great-grandmother Maria Branyas Morera, 115, took the title of oldest person, according to Guinness World Records.
Back in the 18th century, the French naturalist Georges-Louis Leclerc, known as the Comte de Buffon, theorized that a person without accidents or disease could theoretically live a maximum of is 100 years.
Since then, medical advances and improved living conditions have pushed this limit back several decades.
A new milestone was reached when Frenchwoman Jeanne Calment celebrated her 120th birthday in 1995.
Calment died two years later at the age of 122. She remains the oldest person to ever live – at least that has been verified.
According to the United Nations, there are an estimated 593,000 people aged 100 or older in 2021, up from 353,000 a decade earlier.
According to the data agency Statista, the number of centenarians is expected to more than double over the next decade.
The Comte de Buffon might also be surprised at the rise of superlatives – those 110 and older – whose numbers have been increasing since the 1980s.
Natural limit at 115?
So how far can we go? Scientists disagree, with some suggesting that our species’ lifespan is limited by strict biological constraints.
In 2016, geneticists writing in the journal Nature reported that there had been no improvement in human life expectancy since the late 1990s.
Analyzing global demographic data, they found that maximum human life expectancy has decreased since Calment’s death – even though there are more older people in the world.
“They concluded that human lifespan has a natural limit and that life expectancy is limited to about 115 years,” French demographer Jean-Marie Robine told AFP.
“But this hypothesis is partly challenged by many demographers,” said Robine, an expert on centenarians at the INSERM medical research institute.
Research in 2018 found that although the mortality rate increases with age, it slows down after age 85.
According to the study, by the age of 107, the mortality rate is as high as 50-60% per year.
“According to this theory, if there are 12 people at the age of 110, then six will survive to 111, three will be 112, and so on,” said Robine.
A number game
But the more people live to be centenarians, the higher the chance that some will live to a record age.
If there are 100 people living to be centenarians, “50 people will live to be 111, which is 25 to 112 years old,” said Robine.
“Thanks to the ‘volume effect’, there is no longer a fixed limit to the lifespan.”
However, Mr. Robine and his team are publishing research this year that shows mortality rates continue to rise after age 105, further closing the gap.
Does this mean there is a hard ceiling on how long we can live? Mr. Robine won’t go that far.
“We will continue to explore, as we always do, and gradually the health of the oldest people will improve,” he said.
Other experts are also cautious about choosing a side.
France Mesle, a demographer at the French Institute for Demographic Studies (INED), said: “There is no definite answer at the moment.
“Even if they are increasing, the number of elderly people is still quite small and we have not been able to make any significant statistical estimates,” she told AFP.
So the problem could be waiting for the number of centenarians to increase to test the “mass effect”.
And of course, some future medical breakthroughs could soon change everything we know about death.
Eric Boulanger, a French doctor who specializes in the elderly, believes that “gene manipulation” could allow some people to live to 140, even 150 years old.
(Except for the title, this story has not been edited by NDTV staff and is published from an aggregated feed.)
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