There is a natural limit to human lifespan and humans have already reached it, according to an extensive new look at global demographics that confirms French supercentenarian Jeanne Calment was the longest-living person.
Calment died at age 122 in 1997, and it's highly unlikely that anyone will live much longer, reports the study that is published in the journal Nature. A person's chances of exceeding age 125 in any given year is less than 1 in 10,000.
Since Calment and other supercententarians are so rare, the authors believe 115 is the more realistic advanced age that some of us could reach.
"The chances are extremely low to find individuals getting so old, but 115 is an age at death we see a lot and we will see it more and more," senior author Jan Vijg, professor and chair of the Albert Einstein College of Medicine's Department of Genetics said.
He added, "It seems likely that extreme longevity, reaching 115, is to some extent encoded in your genes. But there is no doubt that healthy living -- a balanced diet, exercise, no smoking, etc. -- as well as a dose of luck will help you to reach older ages, but likely not more than 115."
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Vijg and colleagues Xiao Dong and Brandon Milholland analyzed information from the Human Mortality Database that includes data from the 19th and 20th centuries, as well as the 21st century so far. They also studied the International Database on Longevity, which documents the maximum reported age at death in countries around the world.
Human life expectancy has risen fairly steadily and rapidly over the past 150 years in most countries. The authors and others attribute this to food stability in many countries, improved hygiene, cleaner drinking water, vaccination programs, antibiotics, other medical advancements, and improved efforts to prevent health problems, such as by focusing on good nutrition, exercise and public safety.
All of that is hopeful for those of us wanting to live longer and healthier lives, but Vijg said, "While we were very successful in reducing mortality early on -- initially childhood mortality but more recently mortality of people in their 60s, 70s, 80s, 90s -- the rate of improvement has peaked and declines for very old age levels."
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