The data suggests that after decades of life expectancy marching upward because of 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,” said S. Jay Olshansky, a professor of epidemiology and biostatistics at the University of Illinois Chicago, who led the study. He predicted maximum life expectancy will end up around 87 years – about 84 for men and 90 for women – an average age that several countries are already close to achieving.

During the 20th century, life expectancy rose dramatically, spurred by innovations such as 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. Famous demographer James Vaupel maintained that most children born in the 21st century would live to 100.

But according to the new study, that is unlikely to be the case. 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.

Olshansky has long pushed against the idea that life expectancy will steadily climb forever. In a 1990 paper published in Science, he presented a theory that humans were already close to reaching the limit for average life expectancy.

More than 30 years later, 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.

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

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, saying that Olshansky’s study was “well done”.

“He has always been what people considered pessimistic, but I think it’s also realistic,” Vijg said.

The new research suggests that although 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, average peak life expectancy would rise only by one year for women and 1½ years for men.

“We can manufacture a bit more survival time through medical advances,” as well as through reducing health disparities and encouraging healthier lifestyles, Olshansky said.

But, he added, even if deaths from common diseases or accidents were eliminated, people would die of ageing 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.”

Not everyone agrees. Luigi Ferrucci, scientific director at the National Institute on Ageing, concurred that we are unlikely to see substantial increases in life span if the status quo is maintained. But he said investing more in preventive health could change that by delaying the onset of diseases, which in turn could result in “less of that damage that was due to the biology of ageing”.

Nadine Ouellette, an associate professor of demography at the University of Montreal, took issue with another aspect of the study. She said that average life expectancy can “sometimes be misleading” since it is shaped so much by deaths early in life. Instead, she recommended looking at the age at which most people die, called the modal age of death, which focuses more on late life.

For Olshansky, the only thing that might radically lengthen life expectancy is if scientists develop an intervention to slow the ageing process itself – something he’s “optimistic” about, he said.

Austad is also a believer in the potential of anti-ageing medicine. And he said the new paper doesn’t change his bet that a human alive today will reach 150, because it has always been based on “a breakthrough in targeting the ageing process itself”.

This article originally appeared in the New York Times.

Written by: Dana G. Smith

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