Before modern times, the average human lifespan ranged from 20 to 50 years due to limited medical advancements and the widespread impact of diseases and pandemics. However, in the early 20th century, a “longevity revolution” emerged, marked by significant progress in public health and medicine, leading to record increases in life expectancy. What had taken centuries to achieve a one-year increase in life expectancy accelerated to a three-year gain per decade.
Advances in life expectancy have reduced infant mortality rates before spreading to better life outcomes for people in middle and older age groups. Scientists and public health experts continue to debate how long humans can survive, with no consensus on whether human lifespans have a natural limit. Some experts predict that ongoing medical advancements will further extend life expectancy.
In 1990, scientists introduced the “limited lifespan hypothesis,” which predicted that developed nations would maintain an average life expectancy of 85 years but exclusively for women at 88 and men at 82 years unless breakthroughs in biological aging treatments occur. Research indicates that ongoing medical development and behavioral changes may create conditions for “radical life extension,” which could allow most newborns from today to surpass a 100-year lifespan.
The study analyzed population data from Hong Kong and the United States (1990–2019) to assess the feasibility of radical life extension during the twenty-first century. The phenomenon of radical life extension, which brings 0.3-year annual or 3.0-year decennial gains in life expectancy, emerged only in South Korea and Hong Kong in 1990. Yet, most of Hong Kong’s life expectancy gains occurred during its economic growth and the implementation of tobacco restrictions between 1990 and 2000.
The pace by which life expectancy grows has decreased over the past decades regardless of the population groups studied, including Australia, France, Italy, Japan, South Korea, Spain, Sweden, Switzerland, Hong Kong, and the U.S.
A person’s probability of surviving past age 100 ranges from 5.1% for females to 1.8% for males in general populations but reaches its highest point at 12.8% for females and 4.4% for males in Hong Kong. None of the studied populations achieved half of their members’ survival in their 100th year. Lifespan extensions require significantly decreased mortality rates for people of all ages.
Life expectancy has increased continuously since 1950, while the annual growth rate shows a decreasing trend. Available evidence shows declining lifespan differences, which indicates that additional progression may become more challenging. Researchers have concluded that extending the human lifespan to 110 years would necessitate eliminating most leading mortality factors. Only females reach 100 years in 70% of cases, and 6% achieve 150 years in modern times. The 2019 composite mortality data indicates that females can reach their maximum lifespan of 89 years while males reach their maximum of 84 years.
The research analyzes birth survival statistics along with their relationship to initial life expectancy (e(0)) by identifying three important findings which state that better health extends life span, changes in average life expectancy correspond to rising life table entropy (H*) rates, and lifespan inequality (Φ*) decreases. These three metrics form essential tools needed to estimate the possibilities of extreme lifespan prolongation in populations with extended lifespans. The research utilizes data from Japan, Hong Kong, and Switzerland through the Human Mortality Database from 1950 to 2019 to define life extension as a periodic e(0) rise of 0.3 years annually. The analysis includes an alternate scenario of raising life expectancy to 110 years using specific death rates from Japanese females combined with death rate predictions for ages 110 to 150. The lowest mortality rates observed from different populations form the basis for constructing a composite mortality schedule. The presented data, together with the supplied formulas, allow for complete replication of the results, thus demonstrating the critical value of these metrics in predicting future life expectancies.
The analysis highlights constraints on human longevity, demonstrating that progress in increasing life expectancy has declined since 1990, especially for elderly individuals. The “soft limit” has become evident in high-income countries, making further advancements increasingly difficult, although low and middle-income countries can still experience progress in this area. The prediction that numerous people will survive 100 years has introduced uncertainty in both life insurance and retirement planning. The previous increase in life expectancy is largely driven by medical advancements, which are referred to as ‘manufactured time. Scientists face significant barriers in achieving significant breakthroughs in life extension since many expect that most people will not experience dramatic progress during this current century. Research into aging science might create conditions for a future longevity revolution.
References: Olshansky SJ, Willcox BJ, Demetrius L, et al. The implausibility of radical life extension in humans in the twenty-first century. Nat Aging. 2024;4:1635-1642. doi:10.1038/s43587-024-00702-34
