Lived enough! Any radical rise in life span for humans is unlikely, says study

The researchers found that while average life expectancies increased during that time in all of the locations, the rates at which they rose slowed down.

Jeanne Calment of France, writes The New York Times, lived to the age of 122 to be the oldest human to have walked on this planet. What are the odds that the rest of us get there, too? Not high, unless there's a transformative medical breakthrough.

Humanity is hitting the upper limit of life expectancy, confirmed a research published in the journal Nature Aging. The study looked at data on life expectancy at birth collected between 1990 and 2019 from some of the places where people typically live the longest such as Australia, France, Italy, Hong Kong, Japan, South Korea, Spain, Sweden and Switzerland. The researchers found that while the average life expectancy increased in all these places, the rate of rise slowed down, with the sole exception of Hong Kong, where life expectancy did not decelerate.

The data suggests that after decades of life expectancy marching upward, thanks to medical and technological advancements, humans could be closing in on the limits of what’s possible for average life span.

“We’re basically suggesting that as long as we live now is about as long as we’re going to live,” says S Jay Olshansky, a professor of epidemiology and biostatistics at the University of Illinois Chicago, who led the study. He predicted that the maximum life expectancy will end up around 87 years — approximately 84 for men, and 90 for women — an average age that several countries are already close to achieving. “We have to recognise there's a limit” and perhaps reassess assumptions about when people should retire and how much money they'll need to live out their lives.

Mark Hayward, a University of Texas researcher not involved in the study, called the findings “a valuable addition to the mortality literature”. He told The Associated Press: "We are reaching a plateau in life expectancy."

Life expectancy increased dramatically in the 20th century on the back of innovations like water sanitation and antibiotics. Some scientists have projected that this pace will hold as better treatments and preventions are discovered for cancer, heart disease and other common causes of death.

Although Famous demographer James Vaupel maintained that most children born in the 21st century would live to 100, the Nature study says that is unlikely to be. The researchers found that instead of a higher percentage of people making it to 100 in the places they analysed, the ages at which people are dying have been compressed into a narrower time frame.

Dr Olshansky has been known in the science circles as a counter-theorist for steady climb in life expectancy. In a 1990 paper published in journal Science, he presented a theory that humans were already close to reaching the limit for average life expectancy. More than 30 years on, he said his new study offers hard data to back up his original hypothesis - a claim even those who have bet against him say has merit, reports the Times.

Steven Austad, a professor of biology at the University of Alabama who has a wager with Dr Olshansky that a human alive today will reach 150, too said the paper was “excellent” and “establishes beyond doubt” that increases in life expectancy have slowed down.

Jan Vijg, a professor of genetics at the Albert Einstein College of Medicine in New York City who has also researched the limits of human life span, agreed. “He (Dr Olshansky) has always been what people considered pessimistic, but I think it’s also realistic.”

The new research suggests that while modern medicine has helped more people regularly live to their 70s, 80s and 90s, getting the average age up beyond that will prove difficult. For example, the scientists calculated that even if all deaths before the age of 50 were eliminated, the average peak life expectancy would only rise by one year for women and one and a half years for men.

Life expectancy is an estimate of the average number of years a baby born in a given year might expect to live, assuming death rates at that time hold constant. It is one of the world's most important health measures, but it is also imperfect: It is a snapshot estimate that cannot account for deadly pandemics, miracle cures or other unforeseen developments that might kill or save millions of people.

“We can manufacture a bit more survival time through medical advances,” as well as through reducing health disparities and encouraging healthier lifestyles, Dr Olshansky said. But, added that even if deaths from common diseases or accidents were eliminated, people would die of aging itself. “We still have declining function of internal organs and organ systems that make it virtually impossible for these bodies to live a whole lot longer than they do now.”