Scientists: generation born after 1939 won't live to be 100 years old

This is stated in a study published in the journal Proceedings of the National Academy of Sciences.

Scientists from the University of Wisconsin-Madison, the Max Planck Institute for Demographic Research and the French National Institute for Demographic Research analysed data on 23 countries with high income and low mortality. The sample included nations that experienced particularly rapid increases in life expectancy in the 20th century. Six different methods of mortality prediction based on the Human Mortality Database were used.

"The phenomenon of rapid increases in life expectancy in the first half of the 20th century is unlikely to be repeated in the near future," says Hector Pifarre y Arolas, one of the study's authors.

From 1900 to 1938, each new birth cohort showed a 5.5-month increase in life expectancy. Thus, in 1900, residents of developed countries lived on average 62 years, and by 1938 - already 80. But then the growth rate fell: the generations born between 1939 and 2000 had an expected increase of only 2.5 to 3.5 months per generation.

The reason is the exhaustion of key factors that had previously dramatically reduced mortality, especially child mortality. In the early twentieth century, medical advances, improved sanitation and nutrition dramatically reduced infant and child mortality, leading to an impressive increase in life expectancy. Today, however, the rate is so low that further improvements in adulthood no longer have the same effect.

"Our calculations show that even those born in 1980 will not reach an average age of 100 years," says co-author José Andrade.

The researchers emphasise that without dramatic scientific breakthroughs that could dramatically extend life in old age, it will not be possible to return to previous growth rates. And if such breakthroughs do occur, they may be unevenly available in different countries.

Although mortality projections are always dependent on future variables - including pandemics, new technologies or unexpected lifestyle changes - the authors are confident that slowing life expectancy is a sustainable trend.