01/13/2014 11:24 am ET Updated Jan 23, 2014

Why American Women Aren't Living As Long As They Should

Martin Barraud via Getty Images

One of the great victories of the 20th century is that humanity became much smarter about health. We figured out refrigeration, immunization, and that smoking isn't actually good for you, and we began living longer.

In 2006, the average life expectancy at birth was 75 years for American men and 80 years for women, compared with just 48 years for men and 51 years for women in 1900.

But new research shows that while life span has been on a positive overall trajectory for mankind, it's been on a not-so-positive trajectory for the U.S. in particular: Americans' life expectancies might be increasing, but those of other nations are increasing much faster, particularly among women. From 1980 to 2007, for example, the life spans of 50-year-old women in the U.S. had increased by about 2.5 years. But in Japan and Italy, it had increased by 6.4 years and 5.2 years, respectively.

Read more on The Atlantic