Human lifespan may be unlimited, the study says, but biologists disagree

  • The oldest person to ever live reached 122 years, but research suggests that humans could live longer.
  • After people hit 108, they have a 50% chance of living until their next birthday each year, a study says.
  • Theoretically, it suggests that there is no limit to human life, but biologists disagree.
  • See more stories on Insider’s company page.

A person’s chance of dying doubles approximately every nine years.

But that changes if you reach 108, according to a math modeling study published last month. Then your chance of death plateaus to an even 50-50 each year.

“Think of it as a coin toss – when you reach 108, you flip a coin on your birthday. If heads come up, you live to your next birthday. If it comes up with tails, you die before you turn 109,” Anthony Davison, a statistician at the Swiss Federal Institute of Technology who co-authored the study, told Insider. “And if you come to a subsequent birthday, your likelihood of dying does not change.”

By this logic, Davison’s team wrote, this would “mean that there is no limit to human life.”

It is a controversial idea – one that has obviously not been carried by reality.

The longest a human being has ever lived is 122 years, 5 months and 14 days — a record set by Jeanne Calment in France in 1997. The medical and technological advances of the last quarter of a century have not made anyone pass this threshold, despite what statistical models suggest is possible. And although a person’s average life expectancy has increased by decades in the last 100 years or so, our maximum life expectancy has not changed nearly as markedly.

Many biologists believe that it is currently impossible to prolong human life to that extent. But they have long clashed with mathematicians over the question of how long we will have on Earth.

Your chance of reaching 130 is less than one in 1 million

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Jeanne Calment is kissed by two young girls during a ceremony at a nursing home in Arles, France in 1995. Calment died at the age of 122 in 1997 – the only person documented to have lived that long.

Jean-Paul Pelisser / Reuters

To come up with their numbers, Davison’s team looked at mortality data from people who reached or passed 105 years, including 1,100 supercenteners (people 110 years or older) in a dozen European countries, Canada and the United States.

They found that fewer men reached these ages than women – the ratio was one man to every 10th woman. But the 50-50 chance of survival was about the same across genders and geographic locations when people reached 108.

Yet even Davison said his results do not mean people can live forever. There is a catch on the coin toss: the population of people over 108 is halved every year. So if 1,000 supercenteners turn over their coins, an average of 500 die. Then 250 of the remaining die the following year.

By extrapolating this math, Davison’s group concluded that a person’s chance of reaching 130 is less than one in 1 million.

Brandon Milholland, a geneticist at the Albert Einstein College of Medicine who was not involved in the study, told Insider that while it is statistically possible to live to any age, the probability is so exceedingly small that it makes no sense to claim that there is no limit to human life.

In that sense, he said, the new study makes “a mountain out of a molehill.”

“Someone could even live to 1,000, but the probability of that is one in 1 quintillion,” Milholland added. (If all the people who have ever lived in the history of the species were gathered, we would still be missing 1 quintillion.)

Think of life as a flame ride

Biologists claim that our bodies eventually reach a point after which the next disease or illness we get will kill us – that is our maximum lifespan.

Andrei Gudkov, president of cell stress biology at the Roswell Park Comprehensive Cancer Center in Buffalo, New York, said that to calculate the maximum, experts look at the body’s resilience. It is its ability to return to normal function after an illness or biological stressor.

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A family is going on a flame ride on Skegness Pleasure Beach in England in August 2020.

Mike Egerton / PA Images / Reuters

Think of your life as a boat on a timber flight – except that the walls that are supposed to prevent the boat from falling out of the water gradually become shorter as the trip progresses. These walls represent your body’s resilience, which typically decreases as you get older. Imagine illness as a force pushing the boat against the walls. At the beginning of your life, when the walls are high, keep your boat on the right track. But as you get older, these walls shorten, and the same push eventually forces the boat over the edge and off the trip.

“When you reach the point where the resistance goes to zero, even a small disease will make this last fall happen,” Gudkov told Insider. “You can die of everything.”

Resistance decreases with age because as our cells duplicate during our lifetime, they collect mutations. Eventually, these mutations render a cell unable to function properly.

But the exact limit of our species’ maximum lifespan remains up for debate. A 2016 study suggested the upper end is 150, although research from Milholland’s group the same year suggested an age closer to 125.

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French cyclist Robert Marchand is cycling at the indoor Velodrome National in Saint-Quentin-en-Yvelines in Montigny-le-Bretonneux, France at the age of 106 on October 26, 2018.

Christian Hartmann / Reuters

The results of the new study, meanwhile, suggest that someone should be able to beat Calment’s record by at least eight years.

“It is unlikely that any upper limit of human life is below 130 years or so,” the authors wrote.

Léo Raymond-Belzile, one of Davison’s co-authors, told Insider he “could see Joan’s life record being broken in my life.”

‘You have maximized your chance of death’

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Daw Thein Khin, a 100-year-old survivor of coronavirus, prays at his home in Yangon, Myanmar, on October 13, 2020.

Shwe Paw Mya Tin // Reuters

The new study also brings up another much-discussed topic among aging experts: whether our risk of death is ever flat.

A mathematical model from the 1800s, called the Gompertz equation, showed that a person’s mortality risk increases exponentially as they get older – this is how health insurance companies calculate premiums.

But Davison’s study rejects that idea. His group’s calculation instead suggests that when you reach 108, “you have maximized your chance of death,” as Richard Faragher, a biogerentologist from the University of Brighton, put it.

Faragher, who was not involved in the investigation, however, added that “it is a poor comfort because your chance of dying is so great.”

Milholland disagrees. Evidence supporting a mortality plateau is weak and controversial, he said, and it does not make sense that the biological drivers that increase our chances of dying would suddenly stop.

“Although such plateaus exist, they are not even convincing evidence that there is no limit to life,” he said.

centenarian coronavirus vaccine germany

100-year-old Heinz Jacoby receives a coronavirus vaccination from Dr. Anna Häring-Haj Kheder in Bochum, Germany, September 30, 2021.

Roland Weihrauch / picture alliance via Getty

One thing that older experts agree on is that although average life expectancy has increased, there has not been a corresponding increase in our maximum life expectancy.

“This means that even though we treat all age-related diseases, we still die from something that ticks inside us,” Gudkov said.

However, Raymond-Belzile suggested that increasing life expectancy could eventually change the known maximum age. This is because if enough people become supercenteners, the chances of one of them living beyond 122 increase as well.

“The more people who play the game, the greater the chance that someone will be a lucky winner,” he said.

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