One argument being raised in favor of increasing eligibility ages for Social Security and other retirement-related benefits is that increases in life expectancies since those ages were set would allow beneficiaries to collect them for the same portion of their lifetimes. However, life expectancy varies by demographics and has not increased equally across the board, a study has said.

The study by the Center for Retirement Research shows for example that life expectancy of a man in the most-educated quarter of the population who turned age 65 in 2011 is 85, up from 78.9 for one reaching age 65 in 1979.

That difference of 6.1 years outstrips the 4.0 year gain in that time, from 77.5 to 81.5 for men in the lowest quartile.

Among women, the gain in expectancy was not as significant, but the most educated still gained more, 3.2 years to 86.6, than the least educated, 1.4 years to 83.7.

“As a result, assuming people maintain their health, they can work longer while still spending similar proportions of time working and in retirement as those who retired 30 years earlier. Still, policies seeking to extend work lives that treat all workers the same will tend to cut into the retirement of [less-educated] workers more than [more-educated] workers,” it said.