Human Lifespan May Have Reached Natural Constraints

A new study suggests that improvements in survival tend to decline after age 100, and that the age at death of the world’s oldest person has not increased since the 1990s.

Researchers at Albert Einstein College of Medicine (New York, NY, USA) analyzed global demographic data from the Human Mortality Database, which compiles mortality and population data from more than 40 countries. They focused on people verified as living to age 110 or older in four countries--The United States, France, Japan, and the United Kingdom--with the largest number of long-lived individuals. In all four countries, the fraction of each year’s birth cohort (since 1900) who survived to old age increased, pointing toward a continuing increase in average life expectancy.


The researchers found that while super-centenarian lifespan increased rapidly between the 1970s and 1990s, it reached a plateau in 1997 with the death of 122-year-old Jeanne Calment, the longest documented lifespan in history. Using maximum-reported-age-at-death data, the researchers estimated the average maximum human life span at 115 years, considering Jeanne Calment a statistical outlier. Finally, the researchers calculated that 125 years is the absolute limit of human lifespan. The study was published on October 5, 2016, in Nature.

“Demographers as well as biologists have contended there is no reason to think that the ongoing increase in maximum lifespan will end soon, but our data strongly suggest that it has already been attained, and that this happened in the 1990s,” said senior author professor of molecular genetics Jan Vijg, PhD. “Further progress against infectious and chronic diseases may continue boosting average life expectancy, but not maximum lifespan.”

“While it's conceivable that therapeutic breakthroughs might extend human longevity beyond the limits we've calculated, such advances would need to overwhelm the many genetic variants that appear to collectively determine the human lifespan,” concluded Professor Vijg. “Perhaps resources now being spent to increase lifespan should instead go to lengthening health span - the duration of old age spent in good health.”

Since the 19th century, average life expectancy has risen almost continuously thanks to improvements in public health, diet, the environment, and other areas. On average, for example, babies born today in the U.S. can expect to live nearly until age 79, compared with an average life expectancy of only 47 in 1900. Together with observations that lifespan in various animal species is flexible, and can be increased by genetic or pharmaceutical intervention, these demographics led to suggestions that longevity may not be subject to strict, species-specific genetic constraints.

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