PLOS ONE Journal people who have obtained a higher education live longer. Annual deaths association with education are 145,243 not having a high school diploma, 110,068 for people who have only some college, and 554,525 for all people who don't have a BA degree. Who thought not reading would kill you?
It seems almost ridiculous that attending courses and reading books somehow translates into saving hundreds of thousands of lives but this is exactly what is happening. The reasons why this is the case will make a little more sense after you understand all the confounding variables in the study. It isn't necessarily the education but the lifestyle choices.
Higher education is a pathway to understanding and processing information. It impacts everything from our social networks to how we feel about ourselves. If we don't have the right connections, ability to handle our complex world, understand nutrition, motivation, healthcare access, etc... then we are limiting our potential. We die from an inability to navigate our environment or make proper choices.
Our lifestyle determines how long we will live. Higher education helps us increase our lifestyle and handle situations as they occur. We make better choices and understand the consequences of those choices. In the end, all of these small choices add or detract from our life expectancy. Life appears to be a bunch of baby steps that add up to some end. Higher education isn't only about books but also about our lifestyle!
Kruger, et. al. (2015). Mortality attributable to low levels of education in the U.S.. PLOS ONE http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0131809#abstract0