Dividing the population into lifetime earning levels, the committee found that men born in 1930 who reached age 50 had a life expectancy of another 26.6 years if they were in the lowest income bracket and 31.7 years in the highest bracket. But projections for men born in 1960 showed no improvement for the lowest earners — and an additional seven years for the highest. In three decades, the life expectancy gap had widened from about five years to more than 12 — “shockingly large,” Dr. Lee said.

The longevity gains we’ve all heard (and written) so much about, in other words, are going to the men atop the economic ladder.

And, even more strikingly, to the women at the top. Lower-earning women actually have declining life expectancies in simulations that compared the 1960 cohort with those born in 1930. “That’s largely explained by differences in starting and quitting smoking,” Dr. Lee said. But those in the top earnings bracket who reach 50 can now expect, on average, another 41.9 years. The gap by income has surged from four years to more than 13.

Those widening gaps mean that the rich get richer when it comes to federal benefits — Social Security, Medicare and Medicaid. In the 1930 birth cohort, lifetime benefits for low- and high-earning men were about the same. Among those born in 1960, however, men in the highest earning bracket will receive $132,000 more on average than those in the lowest; the highest-earning women will receive $28,000 more.

“The increasing gap in life expectancy means even more inequality over a lifetime,” said Peter Orszag, co-chairman of the committee and former director of the federal Office of Management and Budget.

In an ethnographic study conducted over several years, Dr. Abramson saw how inequality played out in daily life as he visited senior centers, senior housing and nursing homes in middle-class and poor neighborhoods in the Bay Area in California, observing and interviewing (and occasionally driving someone to a doctor’s appointment). “It structures people’s lives in profound ways,” he said.

Middle-class neighborhoods, for instance, had more transportation options, more and better-funded volunteer and social service organizations, more markets within walking distance, better hospitals.