Life expectancy is higher for better-educated males, compared with other demographic groups, a new Harvard study reveals. Women fare worse than men and less-educated females actually showed a slight decline in life expectancy at age 25.

As of 2000, people with more than 12 years of formal education were expected to live seven more years than those who did not advance beyond high school (82 years old compared to 75).

“We’ve found that you can have a rising tide that only lifts half the boats – and the ones lifted are the ones doing better to begin with,” said study co-author David Cutler, dean for social sciences at the Faculty of Arts and Sciences at Harvard University.

Smoking-related illnesses are a factor for much of the mortality gap, according to researchers.

The study, “The Gap Gets Bigger: Changes in Mortality and Life Expectancy, by Education, 1981-2000,” is featured in Health Affairs’ March/April edition.