If you’re hoping to live forever or at least well past 100, researchers may have some good news for you.
A new analysis of population data argues there is not yet an identifiable limit on how long people can live.
Bryan G. Hughes, PhD, and Siegfried Hekimi, PhD, both researchers from McGill University in Montreal, reexamined population data used in a previous study and concluded there is not yet a known limit for human life expectancy.
Their findings published today in the journal Nature argue against the findings of a previous study published in the same journal last October.
That study examined population data on “supercentenarians,” and concluded the maximum life expectancy for humans would likely not exceed an average of 115 years.
In the study published today the authors argue that with a small data set and “noisy” data, the current information does “not permit us to predict the trajectory that maximum lifespans will follow in the future.”
Additionally, they found no support for the original claim “that the maximum lifespan of humans is ‘fixed and subject to natural constraints.’”
“As long as average life span goes up, the maximum life span might go up as well,” Hekimi told Healthline.
What data was used
Hekimi and his co-author used the data from the International Database on Longevity, which provides on individuals who attain ages mainly over 110.
They reanalyzed the data used in the original study, and concluded that trend lines do not indicate there is a plateau to maximum current life expectancy. In part, they argue that “noisy” data, or a relatively small sample of data, did not show a clear trend line, and that there was not yet a clear trend or plateau seen for maximum life expectancy in humans in the future.
Additionally, they argue that new additions to the database from other countries after 1990 may have skewed the data on the average lifespan of these supercentenarians.
Hekimi pointed out to Healthline that due to few people surviving past 110, especially those with verified birth certificates, more data may be needed to understand if there is a determined limit to how long people can live.
“It’s hard to guess,” Hekimi said in a statement released today. “Three hundred years ago, many people lived only short lives. If we would have told them that one day most humans might live up to 100, they would have said we were crazy.”
Other researchers respond
In a reply to Hekimi’s paper, the authors of the original study stood by their findings, calling the new research results “imaginative,” but “not informative.”
They argue that their findings were based on measurable data and not extrapolated out as Hekimi and his co-author had done.
“Taken together, and in the absence of solid statistical underpinning of various possible future scenarios, we feel that our interpretation of the data as pointing toward a limit to human lifespan of about 115 years remains valid,” they wrote.
Dr. Shawn McCandless, a geneticist and Division Chief of Pediatric Genetics at University Hospitals Cleveland Medical Center, said the questions being brought up in this research are ones that geneticists and other medical experts have been studying and debating for years.
“It's a fascinating question for both a practical and philosophical reason," he said referring to the possible set point for human life expectancy.
Speaking about the study’s use of population statistics to determine life expectancy, McCandless said this method results in little information about why some people may live far longer than others.
“They’re fascinating arguments, at the end of the day it doesn’t tell us much,” he said.
What determines longevity?
McCandless explained that in the genetics field, scientists are now looking in a different area for signs that human life expectancy has a set limit: the human genome.
“The genetic underpinnings and determinates of longevity have not been well-studied,” McCandless said.
Currently it’s believed that 25 percent of longevity is determined by genetics, while environmental and other factors make up the other 75 percent, McCandless explained. Much of the genetic research has focused on understanding the mechanisms on a cellular level that affect our longevity.
McCandless explained if certain basic functions of the body are changed or reversed through science, such as using genetic methods to revitalize heart muscle or repair channels in the brain that deteriorate with age, the current limit to human lifespans — even among the supercentenarians — may quickly expand.
“There’s no compelling reason why that particular limit [on life expectancy] is true if you change the rules of the game,” he explained.