(CN) — The oldest human believed to have ever lived was a French woman named Jeanne Calment. She was born in 1875, four years after the end of the Franco-Prussian War, and she died in 1997, having lived for 122 years and 164 days.
Calment may be an outlier, but some have wondered if humans have reached a ceiling on their maximum lifespan. Average life expectancy has been increasing for some time — though it has declined in recent years in some countries, including in the United States. But he oldest humans don't appear to be getting any older. Demographers call this trend in aging "compression." More humans are reaching middle and old age by avoiding various diseases and fatal acts of violence, but mortality amongst older people is steady.
But a new paper, published Wednesday in the journal PLOS ONE, argues the opposite.
"Cohorts born between around 1900 and 1950 are experiencing historically unprecedented mortality postponement, but are still too young to break longevity records," writes David McCarthy, an assistant professor at the University of Georgia. "As these cohorts attain advanced ages in coming decades, longevity records may therefore increase significantly."
"If there is a maximum limit to the human lifespan, we are not yet approaching it," he added.
McCarthy analyzed the morality rates of people aged 70 and older in 19 different countries and plotted how the maximum age differed among different age cohorts throughout the last few hundred years (different countries have different ranges of available data; records in the U.S. go back only as far as 1890, while Sweden's go all the way to 1710).
"The mortality of old people — of people 70 and older — has been improving at a faster rate than at any decade since 1965, when Medicare was introduced," said McCarthy, who pointed to various circumstantial evidence, like Johanna Quass, the 97-year-old German woman who, in 2012, at the age of 86 became the world's oldest active competitive gymnast.
"It’s not something you expect a granny to be doing," McCarthy said."What our analysis suggests is, there will be enough people like her that manage to maintain physical robustness into old age, that mortality records will be broken in the coming decades."
Or simply just look at depictions of middle aged people in the 1800s, or even before that. They look older. Plenty of septuagenarians today look healthy and spry — hence the cliché: 70 is the new 60.
"Look at all the tremendous developments in modern medicine, not to mention changes in nutrition," McCarthy said. "And air conditioning — the degree to which we’re insulated from our natural environment."
Throughout much of the last few centuries, according to McCarthy's research, human life expectancy has gone through compression — that is, more people making it into middle age, but the age ceiling not getting any higher. There have, however, been periods of postponement — of the ceiling getting higher, or of mortality in older people going down. The first half of the 20th century saw a particularly notable period of postponement.
So is this a sign of progress?
"Overall, it’s good news," McCarthy said. "It implies that in some sense, we don’t appear to be prisoners of biology, at least not yet. And the opportunities to increase our enjoyable life span are available. Of course, like with everything in life, that comes with costs."
Humans will likely have to work longer, or else save more money for retirement, or both. Though extreme longevity — living past a hundred years old — will continue to be rare, it may be something that people and governments need to plan for, or make contingencies for. And when paired with a declining birth rate, the shift could further exacerbate the problems of a rapidly aging population.
"The implications of very long lives for public finance are very significant," said McCarthy. "It's a tremendous change in the structure of populations, in a way that has never been seen in the world before."
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