How long can people live? New study suggests there's a limit

Research published in the journal Nature on Wednesday suggests there may be a limit to the human life span — one that's hard to extend without some sort of breakthrough that fixes all age-related problems.

Some aging specialists disagree with finding that human life span likely tops out at about 115 years

Jeanne Calment, pictured in 1995 when she was 120 years old, holds the Guinness World Record for living the longest. She died in 1997 at age 122. (Jean-Paul Pelisser/Reuters)

New research suggests there may be a limit to the human life span — one that's hard to extend without some sort of breakthrough that fixes all age-related problems.

The record for the world's oldest person is 122 years and the odds of shattering that record are slim, according to an analysis published Wednesday in the journal Nature.

"It seems extremely difficult if not impossible to break through that ceiling due to the complexity of the aging process," one of the researchers, Jan Vijg, said in an email. 

The other two authors of the study were Xiao Dong and Brandon Milholland. All three researchers are affiliated with the Department of Genetics at the Albert Einstein College of Medicine in New York.  

Life expectancies in many countries have risen dramatically because of improvements in medical care and sanitation in the last century. The maximum age of death has also increased, leading some to believe that there's no boundary to how long people can live.

In the new study, researchers analyzed data from the global Human Mortality Database. They found that while there have been strides in reducing deaths among certain groups — children, women during childbirth and the elderly — the rate of improvement was slower for people over 100 years old.

Next, they examined how old centenarians were when they died through the International Database on Longevity. The record holder is Jeanne Calment, of France, who lived to be 122. Since her death in 1997, no one is known to have broken her record.

Researchers calculated that the odds of someone reaching 125 years in a given year are less than one in 10,000 and believe the human life span likely maxes out at about 115 years.

Study sparks disagreement

Some aging specialists criticized the study, saying it didn't take into account advances that have been made in extending the life span — and health — of certain laboratory animals including mice, worms and flies through genetic manipulation and other techniques. The goal of such advances is to eventually find treatments that might slow the aging process in humans and keep them healthier longer.

"We can greatly extend the life spans of many different types of animals. I don't think humans are an exception," said David Sinclair, a geneticist at Harvard Medical School and a spokesman for the American Federation For Aging Research.

S. Jay Olshansky, a longevity researcher at the University of Illinois at Chicago, said it remains to be seen just how much further life span can be stretched with technology.

"If we succeed, current limits are likely to be broken. How much they are broken depends on the nature of the breakthrough," he said in an email.

Studies of centenarians have found that lifestyle choices play a bigger role than genetics in their longevity and most were able to delay disease and disability until late in life.

Research has suggested that genes may play a role in the life span of supercentenarians — people who survive to 110 years old or longer. 

Instead of searching for an anti-aging pill, people should focus on eating better and exercising to stay healthy in their twilight years, said Dr. Thomas Perls, a professor of geriatrics at Boston University who heads the New England Centenarian Study.

With files from CBC News