In 1997, at the announced age of 122, Jeanne Calment died in the south of France, set a benchmark for human survival.
Although not everyone is convinced of the authenticity of registration, Calment’s purported age at death is now a rough marker of a potential human lifespan. Among the few dozen people currently over 110 yearsit is unlikely that any of them will celebrate their 125th birthday.
Economist David McCarthy from the University of Georgia and Po-Lin Wang, a risk management and insurance expert from the University of South Florida in the United States, are somewhat more optimistic. They think a real record holder might be just around the corner.
We can’t be blamed for thinking we’ve extracted every drop of longevity from our genes. While there is now more than centenarians than ever before in history, the survivability ceiling seems stuck in the 11th decade and has been for the last century.
McCarthy and Wang used birth cohort mortality data in Human Mortality Databaseusing a Bayesian statistical approach to analyze the lifespan of people born in the same year in 19 currently industrialized countries.
As the number of people living to such an advanced age is statistically somewhat limited, the duo applied a function known as Gompertz’s law to better estimate the age at which one might expect a individual reaches an assumed mortality plateau for the first time.
This “Gompertz Maximum Age,” or GMA, should theoretically allude to an upper limit of human lifespan. If the GMA is fairly constant from one cohort to another, we can assume that there is a maximum age. Advances in medical science may help more people avoid disease and recover from injury, but the distribution of the ages at which we die will simply be compressed into a smaller range.
On the other hand, if GMA increased between cohorts, there might be reason to suspect that mortality is rather “carried over”, meaning that if there is a hard-wired lifespan threshold in our biology , we are yet to see it take effect.
For the most part throughout history, it appears GMA has remained relatively stable. Improvements in sanitation, health care and nutrition have mainly allowed more people to reach old age, compressing the distribution of mortality beyond a certain point rather than expanding it.
Yet there have been distinct periods when this has not been the case.
One was among people born in the decades after the mid-19th century, where the GMA jumped about five years. Although the cause is unclear, the rise has been more pronounced in women. It also describes people who reached their centenarian before 1980, making significant improvements in medical technology and public health measures possible.
A much larger leap in GMA seems to be at work among people born between 1910 and 1950. Currently aged between 70 and 110, one would expect a carryover of mortality equal to about 10 years, implying that at least a few retirees could touch the news by 2060 to celebrate very late birthdays.
The trends could also help explain why registrations appear to have stagnated over the past few decades. The social changes that lead to the postponement of mortality may not affect all cohorts equally, meaning those old enough to have broken longevity records may be too old to benefit from measures that lead to a subsequent postponement episode.
Taken in the context of other studies, advances in medicine and access to social assistance could steadily allow some of our descendants to add decades to our lives.
Do not invest in the birthday candle industry yet. The conclusions of the study are based on many assumptions and speculations, not the least of which is the relationship between health care and a potential postponement of mortality.
“We further emphasize that cohorts born before 1950 will only have the potential to break existing longevity records if policy choices continue to support the health and well-being of older adults, and the political, environmental and economic remains stable,” he added. warn researchers.
Far from being a reason for hope, the study could serve as a warning. Not only could we have more people reaching higher ages, forced to meet the challenges that old age brings with it, a decline in population growth means less support from a young community.
As seen in the the devastating impact of the pandemic on the elderly, society may not be ready for record lengths of life.
This research was published in PLOS ONE.