A likely factor, says Monique Morrissey, an economist at the Economic Policy Institute, is differing access to healthcare. "Not just people who are not insured, but if you have better insurance, you might get tested earlier, have better access to care, and be better able to follow complicated treatments—there have been a lot of improvements in cardiovascular care, especially for men," she says. While behavioral factors such as smoking and obesity likely explain much of the overall connection between wealth and health, they can't account for the growing disparity in life expectancy, since those behavioral factors are not growing disproportionately themselves.
Among younger Americans, health disparities are particularly pronounced, which could adversely affect U.S. life expectancy in the future. Eric Reither, associate professor of sociology at Utah State University, has found that among younger Americans, obesity-related diseases like heart disease and diabetes will likely increase.
As a result, Reither says he envisions two Americas in the coming decades. "One that is relatively poor and adversely affected by obesity and related conditions, and one that is relatively well-off and less affected by these diseases. Life expectancy trajectories for these groups will likely follow different paths, with the former stagnating and perhaps even experiencing some decline, and the latter continuing to inch upward."
As for that magic elixir, a group of British scientists now say they have identified a hormone more prevalent in the wealthy that they link to longevity. The hormone regulates one's stress response and is connected to diet, exercise, and relationships—all known longevity-inducing factors. One can imagine that hormone being packaged and marketed as some kind of magic youth serum, next to antioxidant pills and superfoods.
But for Vaillant, the answer is much simpler. "Those wonderful pills that are marketed to let you live forever—those things just don't seem to be terribly important," he says. Instead, it's making bigger behavioral choices, such as avoiding drinking too much and nurturing a stable marriage, that let people prolong their lives. And as for what makes people happy in old age, Vaillant says it has more to do with strong, loving relationships than anything for sale at a store. Says Vaillant, "I'm 77, and what I enjoy most are my grandchildren."