The death of the world’s oldest person at age 118 has sparked a debate that has divided scientists for centuries: Is there a limit to how long a healthy human can live?
After French nun Lucile Randon died last week, Spanish great-grandmother Maria Branyas Morera, 115, has assumed the title of oldest living person, according to Guinness World Records.
In the 18th century, the French naturalist Georges-Louis Leclerc, known as the Comte de Buffon, theorized that a person who had no accident or illness could theoretically live up to 100 years.
Since then, medical advances and improved living conditions have pushed the limit by a few decades.
A new milestone was reached when the 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 have ever lived – at least that has been verified.
According to the United Nations, there will be an estimated 593,000 people aged 100 or older by 2021, up from 353,000 a decade earlier.
According to data agency Statista, the number of centenarians is expected to more than double in the next ten years.
The Comte de Buffon may also have been surprised by the emergence of supercentenarians – people aged 110 or older – whose numbers have increased since the 1980s.
Natural limit at 115?
So how far could we go? Scientists disagree, with some arguing that the lifespan of our species is limited by strict biological constraints.
In 2016, geneticists writing in the journal Nature said there had been no improvement in human longevity since the late 1990s.
By analyzing global demographics, they found that maximum human lifespans had declined since Calment’s death — even though there were more elderly people in the world.
“They concluded that human lifespan has a natural limit and lifespan is limited to about 115 years,” French demographer Jean-Marie Robine told AFP.
“But this hypothesis is partly disputed by many demographers,” says Robine, a centenarian specialist at the INSERM medical research institute.
Research in 2018 found that while the death rate increases with age, it slows down after age 85.
Around age 107, the death rate peaks at 50-60 percent each year, the study said.
“According to this theory, if there are 12 people who are 110 years old, six will survive to live to live to 111, three to live to live to 112, and so on,” Robine said.
A numbers game
But the more supercentenarians, the more likely a few will live to reach the record ages.
If there are 100 supercentenarians, “50 will live to 111 years old, 25 to 112,” Robine said.
“Thanks to a ‘volume effect’, there are no longer fixed limits to the lifespan.”
However, Mr Robine and his team are publishing research this year that will show that the death rate continues to rise after age 105, narrowing the window further.
Does this mean there is a hard ceiling on how long we can live? Mr. Robine does not want to go that far.
“We will continue to make discoveries, as we have always done, and little by little the health of the oldest people will improve,” he said.
Other experts are also careful about choosing a side.
“There is currently no definitive answer,” said France Mesle, a demographer at the French Institute of Demographic Studies (INED).
“Even if they increase, the number of people living very old is still quite small and we still cannot make a significant statistical estimate,” she told AFP.
So it may be a matter of waiting for an increasing number of supercentenarians to test the “volume effect”.
And of course, some future medical breakthroughs could soon turn everything we know about death upside down.
Eric Boulanger, a French doctor specializing in the elderly, said “genetic engineering” could enable some people to live 140 or even 150 years.
(Except for the headline, this story has not been edited by NDTV staff and is being published from a syndicated feed.)
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