Humanity has been challenging the barriers to longevity for more than a century: a baby born at the beginning of the 19th century had a life expectancy of about 30 years; Today, a child of the new millennium in the most developed countries comfortably exceeds the expectation of 80. Medical and public health advances have pulverized all the theoretical limits of life expectancy. In the 1920s, the ceiling was projected to be at 64; mid-century, which would be 73 for men and 79 for women. But the question of how much longer human beings can live continues to loom in the air.
The scientific community has debated in recent decades whether the longevity revolution that occurred in the 20th century, with accelerated growth in life expectancy, was coming to an end. The so-called radical life extension: three more years added for each decade. Some scientists projected in 1990 that the growth of life expectancy would slow down in the 21st century, but other currents proposed that this hypothesis did not take into account the advances underway in medicine and biology and even predicted that the majority of newborns Today they would live to be 100 years old or more. The discussion continues, but new research published this Monday in the journal Nature Aging assures that the radical increase in life expectancy that was experienced in the 20th century is slowing down. The authors suggest that it is “unlikely” that more than 15% of women and 5% of men will be centenarians this century.
The scientists analyzed mortality data from the nine regions in the world with the highest life expectancies (Hong Kong, Japan, South Korea, Australia, France, Italy, Switzerland, Sweden and Spain) and the United States between 1990 and 2019 and reported that, in these 30 years, general improvements in life expectancy have slowed. “The longevity revolution is approaching its peak, just as we predicted it would when we first addressed this topic about 34 years ago,” said Jay Olshansky, a professor at the University of Illinois College of Public Health in Chicago. , United States) and author of the study. And he adds: “Although it is still possible to increase it by reducing diseases, the gains in longevity in Spain and other parts of the developed world will now be small. “This doesn’t mean we should stop trying to fight disease, it just means that there will be fewer and fewer longevity benefits from that investment.”
To maintain the longevity revolution that humanity has experienced during the last century, this extension of three years every decade would have to continue. But the research reported that the only regions that experienced this radical pace since 1990 were South Korea and Hong Kong. In the rest of the populations, “the annual increase in life expectancy has slowed to less than 0.2 years per year,” they point out in the scientific article. The United States, furthermore, is one of the few documented countries that have recorded a lower life expectancy at birth at the end of any decade relative to the beginning of the decade. This phenomenon, the authors explain, also occurred in the first half of the 20th century, but was caused by extreme events, such as wars or epidemics.
Scientists assure that “it has become progressively more difficult” to increase life expectancy and the milestone of the majority of the population reaching 100 years of age seems, for now, unattainable. “There is no evidence to support the suggestion that the majority of today’s newborns will live to be 100 years old,” the authors emphasize. In fact, they did not find any population that is close to 50% survival at 100 years of age: the highest probability of exceeding 100 years of age in a population was detected in Hong Kong, where they expect, according to their 2019 mortality data, that 12.84% of women and 4.4% of men become centenarians.
The uncertain milestone of massively reaching 100 years of age
“It would be optimistic that 15% of women and 5% of men in any human birth cohort could live to age 100 in most countries this century,” the authors note. That limit, theoretically, could be surpassed if therapies were developed that slowed down human aging. But even so, they warn, “survival to age 100 for most people is not a certainty.” For now, the authors exemplify, the efforts of the Intervention Testing Program of the National Institute on Aging of the United States to find potential therapies to delay aging have “limited effectiveness”: of the 50 compounds investigated, only 12 have increased hope of life, but none more than 15%.
Olshansky and her team’s analysis showed that for a second wave of radical life extension to result in a life expectancy at birth of 110 years in the future, “70% of women are required to survive to 100″. Or put another way: to reach the threshold of 110 years of life expectancy at birth, almost one in four women would have to survive to 122 years, which is the maximum life expectancy observed in human beings. The Frenchwoman Jeanne Calment, considered the dean of humanity, died in 1997 at that age. “To radically prolong life, it would also be necessary for approximately 6% of women to survive to age 150, that is, 28 years longer than the oldest documented human being in history,” they illustrate.
Olshansky admits that “it is perfectly possible” that the increase in life expectancy will come to a complete halt. Although he adds that there is still room for maneuver to continue improving slightly. “All nations have the capacity to increase it further, if only by reducing disparities between population subgroups, but also by modifying risk factors, such as reducing obesity and smoking,” explains via email. According to their analysis, life expectancy at birth as of 2019 is 88.68 years for women and 83.17 years for men. However, other research in 2019 estimated potentially higher life expectancies by 2039: 91.6 years for women and 86.1 for men.
Optimism and biological limits
The authors of this study reject a hopeless interpretation of their findings and argue that “humanity’s battle for long life has already been largely achieved.” “This is not a pessimistic view that the longevity game is over or that it is no longer possible to continue improving mortality at all ages (especially at older ages); or that it is no longer possible to improve life expectancy by modifying risk factors or reducing survival inequalities. Rather, it is a celebration of more than a century of public health and medicine that have allowed humanity to gain advantage over the causes of death that, until now, have limited human longevity,” they conclude in the article.
Although their evidence indicates that “human life expectancy due to the first longevity revolution has ended,” the authors say there is room for optimism and “a second longevity revolution may be near in the form of modern efforts to slowing biological aging, offering humanity a second chance to alter the course of human survival.” But while this scenario does not arrive, the authors return to the data of their analysis and assure that it is “unlikely” that in this century there will be a radical extension of life in these regions studied.
Mercedes Sotos Prieto, Ramón y Cajal researcher at the Complutense University of Madrid and the Networked Biomedical Research Center for Epidemiology and Public Health, assures that this study, in which she has not participated, “provides evidence about the slowdown in the improvement of life expectancy”, but warns that it will not necessarily settle the scientific debate about what its ceiling is. “Although it seems that we have reached a certain limit, the debate could continue as new advances and discoveries emerge,” he says.
Demographer Rosa Gómez Redondo, a university professor and member of the Human Mortality Database and the Longevity Database, agrees on this point: more than settling debates, this study “provides new data, delaying in time reaching proposed forecasts.” before”. “Each new generation presents new features in its demographic behavior compared to its parents, so the debate continues based on the evolution of environmental risks, the response of the science of the time, the regularity with which socioeconomic crises occur, of outbreaks of new diseases (which are not considered here) and the evolution of the main causes of death of the time,” reflects the scientist. Gómez Redondo, who has not participated in this research either, calls Olshansky’s study “a notable contribution by a leading demographer” in the analysis of longevity in the 20th and 21st centuries.
Sotos Prieto attributes the slowdown in life expectancy at birth to the biological limits of aging. But it also highlights other possible causes, such as the role of “unhealthy lifestyles, increasingly sedentary and with diets of poorer nutritional quality.” “Perhaps another aspect is inequalities in access to medical care. If this became smaller, it would still increase a little more,” he adds.
Life expectancy in Spain: 83.1 years
Lola Sánchez Aguilera, expert professor in Regional Geographic Analysis at the University of Barcelona, remembers, in any case, that the evolution of life expectancy is not always upward. There may be surprises. “History has shown us that progress is not linear and there can be setbacks. We have already had some scares, such as the AIDS epidemic or, more recently, the covid one,” he warns. In Spain, for example, life expectancy at birth in 2022 – the latest year for which figures are available – was 83.1 years (80.3 in men and 85.8 in women). These data represent, according to the latest report from the Ministry of Health, published this Monday, an improvement after the impact of the covid pandemic – it caused a decrease of 1.5 years in life expectancy in 2020 – but it has not yet been confirmed. have reached levels prior to the health crisis (in 2019, life expectancy at birth was 83.5).
Gómez Redondo admits that, in the coming decades, “it is possible” that there will be periods of stagnation in life expectancy, followed by subsequent advances. And he defends: “It is foreseeable that life expectancy of 100 or more years will be reached, but it will not be, in view of the data, in the 21st century.” To achieve this second revolution of longevity, the demographer points in several directions: the “decrease in mortality linked to the aging of the population”, the delay of biological aging, the reduction of the probability of death according to socioeconomic inequalities and “the elimination or change in the trend of premature mortality in adults, especially that caused by tumors at young ages, which has been increasing in recent decades in the world.”
What Gómez Redondo does warn is that the singular case of Calment, who reached the age of 122, is not feasible as a global life expectancy goal: “It can be considered as a horizon to be achieved, but it is unthinkable as a life expectancy of a population globally, at least in the current state of scientific knowledge and the availability of health resources by socioeconomic level foreseeable in the near future.”