Increases in human life expectancy have slowed dramatically across the world since 1950, according to a study from researchers at Johns Hopkins Bloomberg School of Public Health. Although a “ceiling effect” is expected as average lifespan approaches its biological limit, the study found that the trend towards slower gains—and even declines—in lifespan is worst among low-lifespan countries.
“This is not about us hitting the ceiling; the slowdown has been sharpest in countries that have the most life expectancy to gain,” says Dr. David Bishai, professor in the Bloomberg School’s department of population, family and reproductive health.
The finding, reported in BMC Public Health on January 17, does not have a clear explanation, although it shows that progress in health technology since 1950 has not been enough to keep longevity increasing at its historic rates in populations.
Dr. Bishai and Ms. Carolina Cardona, a PhD student at the Bloomberg School, examined life expectancy data for 139 countries and for each one calculated the “decadal” life expectancy gain — the gain from a given year to a decade later — during the period 1950 – 2009. The analysis revealed that for the total sample, the mean decadal gain started at an impressive 9.7 years during the 1950s but fell more or less steadily to just 1.9 years during the 2000s. The study did not break down data by country or region.