According to a new study of expected lifespans between 1990 and 2019, the sharp increase in life expectancy over the past century is finally slowing down – and will stop when the average life expectancy reaches 87 years.
The study, published last week in Nature Aging by gerontologist Jay Olshansky and several co-authors, found that the increase in life expectancy over the course of the 20th century has slowed markedly over the past 30 years.
The study examined data on life expectancy at birth collected between 1990 and 2019 in the eight countries with the highest life expectancy: Australia, France, Italy, Japan, South Korea, Spain, Sweden and Switzerland. It also looked at lifespans in Hong Kong and the United States.
The new study follows research that Olshansky, now a professor of epidemiology and biostatistics at the School of Public Health at the University of Illinois at Chicago, undertook before 1990. Average life expectancy for the world as a whole he is currently 72 years old.
Olshansky argued in 1990 that the world was nearing the end of a “longevity revolution” and that there was only so far medicine could take us before we succumbed to the aging process anyway. His latest study provides more concrete evidence to support this claim.
Why has life expectancy increased so much in the last century?
About 100 years ago, between the end of the 19th and the beginning of the 20th century, the average life expectancy was about 50 years. By 1990, this had risen to around 70 – and in richer countries it reached the mid-80s – following what researchers call a “longevity revolution”.
Advances in medical care, which prevented the deaths of newborns and women during childbirth, in particular, were responsible for the first longevity revolution which saw the life expectancy of men and women increase dramatically because women and children who previously would have died early in life were now living to a “normal” age.
“You can only save children once, and once you do, these children who would normally have died at a much younger age are now living much, much longer than they would have been,” Olshansky explained.
Since the late 20th century, the medical industry has turned its attention to diseases and disorders that have become more prolific as we live longer, including heart disease, cancer, stroke and Alzheimer’s disease. Today, people survive these conditions thanks to better medicine.
What does the new study show?
The study looked at data on life expectancy at birth collected between 1990 and 2019. The study deliberately stopped at this year to eliminate any artificial mitigation caused by the COVID pandemic.
“Upper average” life expectancy has already exceeded 85 years in some of the richest countries studied – around 88 for women and 82 for men.
The new study predicts that maximum life expectancy will stop at around 87 years – 84 for men and 90 for women – which some countries are already close to reaching. After that, however, the average age at death would stop increasing.
The focus of the study was what scientists call “life table entropy,” which suggests there are limits to the scope of the longevity revolution.
“When you live to these increasingly advanced ages, into your 70s, 80s, 90s, 100s, you run into a problem,” Olshansky says. “That problem is the biological process of aging itself, the aging of our cells, tissues, organs, organ systems that we call senescence.
“So when you push survival into an age window where it collides with the immutable force of biological aging, the increase in life expectancy must slow down.”
Ultimately, the study showed that the only way to extend lifespan from this point on is to slow down the aging process itself.
Can we slow down the aging process?
Thanks to advances in medical technology, life expectancy will most likely continue to increase, but it still remains a limitation due to natural aging. Therefore, the next step in continuing the “longevity revolution” is to slow the aging process itself, something Olshansky says he is “hopeful” can happen. It is certainly something under study.
“Given the rapid advances now occurring in geroscience, there is reason to be optimistic that a second longevity revolution is approaching in the form of modern efforts to slow biological aging, giving humanity a second chance to alter the course of human survival,” the study states. .
Geroscience is the study of the biological process of aging; in short, what causes our bodies to age.
According to the researchers, healthy centenarians (those who have reached 100 years old) and supercentenarians (those above 110 years old) can also be studied to understand the underlying conditions and environment that contributed to their long lifespan.
Some individuals who live to old age may possess some sort of genetic signature, further study of which could provide answers to the question of what causes longevity.
“It’s likely that there are specific genes that they have that make proteins in their body that protect them from things that kill the rest of us at a young age,” Olshansky says.
Studying other long-living animals can also offer insights. “This is one reason scientists want to study other long-lived species. How is it possible for a bowhead whale to live 210 years? How is it possible for a Greenland shark to live 500 years?” he added.
What did the study tell us about individual countries?
The study also revealed country-specific findings. While the root cause of this finding is unclear, Hong Kong is experiencing a stronger increase in life expectancy than most countries.
The study found: “The highest population-specific probability of surviving to age 100 occurred in Hong Kong, where 12.8% of females and 4.4% of males were predicted to reach age 100 in their lives based on the 2019 life tables”.
According to the most recent World Bank data from 2022, the average life expectancy for Hong Kong is 84 years while the average life expectancy for the world is 72 years.
In the study, a life table shows the probability of surviving or dying at different ages in a particular population.
The study revealed that the improvement in life expectancy in Hong Kong was due to economic prosperity and smoking bans introduced between 1990 and 2000.
However, in all countries, including Hong Kong, an autonomous territory of China, “the last decade of life expectancy change is slower than in the last decade of the 20th century,” the study concludes.
Of the 10 countries studied, the United States showed the slowest improvement in life expectancy. According to 2022 World Bank data, the average life expectancy in the United States is 77 years.
Why is life expectancy slowing down especially in the United States?
Olshansky attributes part of the slowing life expectancy in the United States to a lack of access to universal healthcare. The United States operates an insurance-based healthcare system, unlike the vast majority of Western countries, where healthcare is financed largely by taxation and is accessible to all. In the United States, the bifurcation between those who have access to high-quality healthcare and those who do not is stark. A subset of the population is therefore lowering the overall average in the United States due to disparities in the quality of healthcare.
“A subset of the population, who are wealthy, highly educated, have access to health care, take their medications when they see the doctor, actually go to the doctor, have access to doctors. Now you have this other subgroup of the population, which is much larger than the first, and this other subgroup of the population is less educated, has less access to healthcare,” says Olshansky.
