The pace of life expectancy growth has slowed down in prosperous countries.

For the past two thousand years, human life expectancy has gradually increased at a rate of one year every 100-200 years. However, in the 20th century, this pace sharply accelerated—every decade added three years to life expectancy.

This shift began with a significant reduction in child mortality at the beginning of the century, followed by improvements in the quality of life for adults and the elderly. In affluent countries, the number of centenarians and "super-centenarians" started to rise. Will this trend continue? Scientists are divided into two camps regarding this issue.

The hypothesis of a limit on life expectancy emerged in the early 1990s. According to this theory, the average life expectancy in national populations is unlikely to exceed 85 years (88 years for women and 82 years for men). Biological aging serves as a natural barrier.

In contrast, there is the hypothesis of radical life extension. Proponents of this view believe in the continual progress of aging science. According to Russian scientists Leonid and Natalia Gavrilov, the limit on life expectancy is not defined and depends on human efforts to extend life. Gerontologist Steven Austad stated that among those born before 2001, there are individuals who will live to 150 years.

To determine which hypothesis is closer to the truth, researchers from the United States, led by Jan Olshansky from the University of Illinois, undertook the task. They utilized standard demographic metrics from 1990 to 2019 across eight countries with the highest life expectancy: Australia, France, Italy, Japan, South Korea, Spain, Sweden, and Switzerland. For comparison, they included data from Hong Kong and the United States. The findings of this research were published in the journal Nature Aging.

The main question that interested the authors was whether we should expect a similarly sharp increase in life expectancy as seen in the 20th century. The analysis revealed that only South Korea maintained a record pace—over 0.3 years per year, with Hong Kong showing good dynamics. The others slowed down, and in the last decade, the pace has begun to decline, including in both leading countries.

On average, in the eight selected countries and Hong Kong, people lived 6.5 years longer during the study period. In the U.S. and several other countries, life expectancy actually decreased. This was observed in the early and mid-20th century due to various events, such as the Spanish flu and the world wars.

The researchers also projected the share of centenarians in the populations. Among women, this is expected to be 5.1 percent, and among men, 1.8 percent. Hong Kong leads, where the share of female centenarians will be 12.8 percent, and male centenarians will be 4.4 percent.

“Since 1990, life expectancy has not increased at a pace that would require a radical scenario. In the future, this is unlikely unless there is a breakthrough in combating biological aging,” concluded the study authors.

In their view, a sharp increase in life expectancy is to be expected in some low-income countries. This will mark their first longevity revolution, which more prosperous countries have already experienced.