This is strange news: According to an article by Monica Potts in The American Prospect magazine (an excellent publication, by the way), over the past 18 years, the life expectancy of white American women who are not high school graduates has dropped by five years.
On the whole, Americans who are white have significantly higher life expectancy than those who are black, and the better educated tend to outlive the less educated. Those discrepancies are a source of concern and should be addressed. But most groups are at least living longer than their counterparts in the past, with an unexpected exception:
Between 1990 and 2008, the life expectancy for white men who did not graduate high school fell three years. For women the difference was an even more remarkable five years.
Most Americans, including high-school dropouts of other races, are gaining life expectancy, just at different speeds. Absent a war, genocide, pandemic, or massive governmental collapse, drops in life expectancy are rare. "If you look at the history of longevity in the United States, there have been no dramatic negative or positive shocks," Olshansky says. "With the exception of the 1918 influenza pandemic, everything has been relatively steady, slow changes. This is a five-year drop in an 18-year time period. That’s dramatic."
(That's S. Jay Olshansky, lead author of the paper in Health Affairs.)
In fact, among Americans without a high school diploma, black women are now outliving white women.
Recall that life expectancy is a type of average. When we hear that life expectancy in antiquity was in the 30s or so (estimates vary) we tend to think of this as a typical age of death. In fact, the average was brought sharply down by high infant and childhood mortality. Those who survived into adulthood tended to live almost as long as people do today. The 90th Psalm describes a typical lifespan as 70 years, or 80 for the very healthy.
I'm fairly sure (though I don't recall seeing this spelled out) what we're actually talking about in this specific context is the remaining life expectancy for persons who have reached adulthood, that is, those old enough to have had time to complete high school. Hence a fall in life expectancy probably means that more are dying in their 20s through their 50s.
There's far more in the article than this brief summary suggests, including a discussion of possible explanations.