In the 1990s, many scientists doubted the warning of an epidemiologist that the rapid extension of human life expectancy in the 20th century would stall. Now, a new study shows that the epidemiologist was correct.
The astonishing increase in global life expectancy in the 20th century is remarkable. In 1900, the average life expectancy for newborns was just over 30 years, and by 2021, this number had reached 71 years. Due to advances in medicine and technology, for most of the last century, the life expectancy in developed countries has been increasing by about three years every decade.
Many scientists predicted that this phenomenon, known as “radical life extension,” would continue indefinitely. Some even claimed that the majority of people born today will live to be a hundred. However, in 1990, epidemiologist S. Jay Olshansky (currently at the University of Illinois at Chicago UIC) published a controversial study questioning this. He believed that despite undeniable advancements in medical field, the increase in life expectancy would slow down and eventually stabilize around an average of 85 years.
“In 1990, we predicted that life expectancy increase would slow down, and what we refer to as ‘Band-Aids’ style medical interventions would have less impact on life expectancy,” Olshansky told CNN. “Many people disagreed with us,” he added, “saying, ‘No, no, no!’ Advancements in medicine and life extension technologies will accelerate, and extend life expectancy to even higher levels.”
Now, Olshansky and his collaborators have conducted a new study and published it on October 7th in “Nature Aging.” The research results suggest that he was right. Data shows that while human life expectancy is still increasing in developed countries, the rate of increase is slowing down, indicating that human life expectancy may be approaching a biological limit.
“We waited thirty years to see what actually happened, so we now know the answer, and that is what is contained in this paper,” Olshansky told Gizmodo, “and the answer is what we predicted.”
To arrive at this conclusion, the researchers examined data from several countries with the longest life expectancy from 1990 to 2019: Australia, France, Italy, Japan, South Korea, Spain, and Switzerland. Researchers also included Hong Kong and the United States, though the average life expectancy in the US did not approach the top ranks, and according to reports, it has actually decreased in recent years.
Overall, the analysis found that the rate of increase in average life expectancy in Australia, France, Italy, Japan, Spain, Switzerland, and the US has slowed down over the decades. South Korea and Hong Kong were the only ones whose improvements sync with the predicted “radical life extension,” but researchers suspect this may be because their life expectancy growth concentrated in recent years.
According to the Associated Press, in 1990, life expectancy was expected to increase by about 2.5 years per decade, but by the 2010s, this increase had decreased to 1.5 years, almost zero in the US.
To further emphasize this point, the research team calculated what the current human life expectancy would be if those staunch supporters of “radical life extension” were correct. According to Scientific American, if that were the case, 6% of Japanese women today would live to be 150, and one-fifth of the population would live past 120. Clearly, this scenario has not materialized.
The focus is on increasing healthy life expectancy. Luigi Ferrucci, scientific director of the National Institute on Aging who did not participate in this study, told The New York Times that he may not entirely agree with the study’s conclusion. He pointed out that advances in preventative health science could delay the onset of age-related diseases, reducing damage caused by “age biology.” However, he also added that without advancements in preventative health, average life expectancy may not increase.
Scientists note that overall, this study supports shifting efforts towards slowing aging and increasing healthy life years. According to the research statement, this means extending a person’s healthy life, not just their lifespan.
“We can only push the limits of human survival so far,” Olshansky told Nature News. “If you live long enough, you will face the biological process of aging.”
However, he added that this is actually a good thing. “This is a success outcome, not a failure outcome. It’s about allowing people to live long enough to experience the biological aging process, which is now the primary risk factor.”