Implausibility of radical life extension in humans in the twenty-first century

Abstract

Over the course of the twentieth century, human life expectancy at birth rose in high-income nations by approximately 30 years, largely driven by advances in public health and medicine. Mortality reduction was observed initially at an early age and continued into middle and older ages. However, it was unclear whether this phenomenon and the resulting accelerated rise in life expectancy would continue into the twenty-first century. Here using demographic survivorship metrics from national vital statistics in the eight countries with the longest-lived populations (Australia, France, Italy, Japan, South Korea, Spain, Sweden and Switzerland) and in Hong Kong and the United States from 1990 to 2019, we explored recent trends in death rates and life expectancy. We found that, since 1990, improvements overall in life expectancy have decelerated. Our analysis also revealed that resistance to improvements in life expectancy increased while lifespan inequality declined and mortality compression occurred. Our analysis suggests that survival to age 100 years is unlikely to exceed 15% for females and 5% for males, altogether suggesting that, unless the processes of biological aging can be markedly slowed, radical human life extension is implausible in this century.

Fig. 1. Average annual change in life expectancy at birth (in years), by decade, in nine populations with the highest life expectancy and the United States: 1990s, 2000s and 2010s.

Source: Human Mortality Database (2019 complete life tables by sex). Threshold annual improvement in life expectancy at birth of 0.3% is required to demonstrate that radical life extension has been or is occurring. The rate of improvement in life expectancy at birth has decelerated in every population except Hong Kong. The dashed line indicates the average annual change in e₍₀₎ associated with ‘radical life extension’.

Fig. 2. Observed percent survival to age 100 (males and females) in the eight countries with the longest-lived populations and in Hong Kong and the United States (1990–2019).

Each line represents the proportion of each population in an annual life table who would survive to age 100 from 1990 to 2019.

Fig. 3. Percentage reduction in death rates from all causes at all ages required to raise period life expectancy at birth by 1 year, males and females (1750–present).

The panel on the left illustrates how much death rates from all causes at all ages are required to decline for females to add 1 year to life expectancy at birth; the panel on the right shows the same results for males. The black vertical lines are indicators of beginning of a century.

Fig. 4. Annual change in the log of life expectancy at birth in ten populations from 1950 to 2019.

Shown is the log of life expectancy at birth in the eight countries with the longest-lived populations and in Hong Kong and the United States (1950–2019).

Fig. 5. Life table entropy and lifespan inequality in all ten populations with the longest-lived populations (1950–2019).

a, Annual changes in life table entropy for all 10 populations from 1950 to 2019. b, Annual changes in lifespan inequality for the same populations and time periods.

Fig. 6. Required survival dynamics to ages 100, 122 and 150 for Japanese females and with radical life extension.

Evidence for radical life extension requires a mortality distribution that is dramatically different from observed mortality distributions observed among the longest-lived human populations (denoted by A). A mortality distribution for a population experiencing radical life extension today requires just over one-fourth of the birth cohort surviving beyond the age of the maximum lifespan for the species (denoted by B). Approximately 6–7% of the birth cohort would need to survive to age 150 to achieve radical life extension (denoted by C).