Humankind may have hit a wall when it comes to our capacity to grow older. Scientists now believe that there may be a natural limit to our lifespan and it has already arrived.
Both human life expectancy and the maximum age at death have increased steadily throughout the 20th century as sanitation improved and better medical treatments emerged.
But this trend has slowed down and may actually have stopped says Xiao Dong, Brandon Milholland and Jan Vijg of the Albert Einstein College of Medicine write in a letter published on Wednesday in the journal Nature.
They used data from the Human Mortality Database and the International Database on Longevity to track the trends and try and establish whether there was no upper limit to how long we could live.
Unfortunately, they found that the answer is probably no. The continued improvement in survival began to flatten around 1980 and this was seen in 36 of the 41 countries in the database.
Theresearchers actually set the peak of improving longevity in the year 1995, very close to the year of death at the ripe old age of 122 years of the French “supercentenarian” Jeanne Calment.
No one has yet exceeded her record lifespan.
The researchers built a model based on the data and have come to the conclusion that the odds are set against anyone reaching 122 years again. In fact the numbers say that the limit to maximum reported age at death currently stands at 114.9 years, well under the record set by Calment.
“Our results strongly suggest that the maximum lifespan of humans is fixed and subject to natural constraints,” the authors write. This does not however mean that we are preprogrammed for death once we reach some biological, gene-driven countdown.
Having genes with this specific purpose would fly in the face of evolution which works to prolong not cut short survival. Rather it seems to be a matter of things just wearing out.
In fact the rot seems to set in fairly quickly once we hit the century. "Here, by analysing global demographic data, we show that improvements in survival with age tend to decline after age 100," they say.
The most long-lived Irish person was Kathleen Snavely from Co Clare who died in the US aged 113 years in 2015.
The findings were consistent with what other researchers are finding, said Prof Rose Anne Kenny, principal investigator in Tilda, the Irish Longitudinal Study on Ageing research centre based at Trinity College Dublin.
“I am not entirely surprised. It makes sense there would be a natural limit to lifespan,” she said. Improvement in lifespan had been steadily upwards since the 1840 but first began to flatten out from the 1950s she said.
