A study by American scientists has shown that since 1990, the overall increase in life expectancy has slowed compared to earlier periods. According to an article published in the journal Nature Aging, the number of people who will live to be a hundred is unlikely to exceed 15 percent for women and 5 percent for men.
Until the mid-19th century, life expectancy at birth ranged from 20 to 50 years. Advances in public health and medicine in the early 20th century led to a dramatic increase in life expectancy, reaching up to 100 years. However, the rate of increase in life expectancy at birth continued to be influenced by geography, economic development, and time. In general, the transition to longer life consisted of a decline in early mortality, followed by a decline in old age mortality.
Accurately forecasting future trends in life expectancy has important implications for social, health, and economic policy. For example, some countries are known to be experiencing a significant increase in the proportion of elderly (i.e., non-working) populations. Different theories have suggested different upper limits for human life expectancy, but these can only be confirmed or refuted in retrospect.
A research team led by S. Jay Olshansky of the University of Illinois at Chicago used standard demographic survival rates from the 10 countries with the longest life expectancies (Australia, Hong Kong, Spain, Italy, the United States, France, Switzerland, Sweden, South Korea, and Japan) from about 1990 to 2019 to determine which hypothesis about human life expectancy the data supported. It found that life expectancy at birth in 2019 was 88.68 years for women and 83.17 years for men.
The initial analysis found that the only countries to achieve increases in life expectancy of 0.3 years year-on-year or 3.0 years decade-on-decade (the de facto definition of a radical life extension) were South Korea and Hong Kong. In Hong Kong, where life expectancy rose by 6.5 years, much of this was due to economic prosperity and tobacco control, but most of the gains in life expectancy occurred in the 1990s. Overall, in all the countries studied except Hong Kong and South Korea, annual increases in life expectancy have slowed compared with the 20th century, to less than 0.2 years per year.
Between 1950 and 2019, age at death has been shrinking to a shorter period of time at the limit of human survival. Since 1990, life expectancy has not increased at a rate that would constitute a radical extension of life, and is unlikely to do so without breakthroughs in slowing the rate of human aging. The average probability of newborns in the countries studied surviving to 100 is 5.1 percent for women and 1.8 percent for men, with the highest population probability of surviving to 100 in Hong Kong, where 12.8 percent of women and 4.4 percent of men will reach 100 in their lifetime.
The scientists also showed, using Japan as an example, how mortality must be reduced for life expectancy at birth to increase by one year. The mortality rate from all causes at any age needed to increase life expectancy for women to 89 years must decrease by 20.3 percent. For men, increasing life expectancy from 82 to 83 years would require a decrease in overall mortality at each age by 9.5 percent.
A second wave of radical lifespan extensions that would increase life expectancy at birth by 110 years would require about 70 percent of women to live to age 100, and 24 percent to age 122, the maximum lifespan recorded for humans. Another six percent of women would have to live to age 150.
However, these results may change after adjusting for the Covid pandemic. For example, we have already reported that it reduced life expectancy by 1.8 years.
