A web of correlations links health, longevity, wealth, education, and intelligence. More intelligent and educated people tend to be wealthier. They also tend to live longer. All sorts of sensible causes can be proposed, such as those involving better access to medical services and a better ability to make use of that access, or the education, willpower, and peer pressure to make improved lifestyle choices. Don't get fat, keep exercising, and so forth: over the long term calorie restriction and regular exercise produce benefits to health and life expectancy in the average individual that are large in comparison to that provided by any presently available medical technology. There are less usual suggestions as well, such as the possibility of a biological connection between better health and greater intelligence.
Biology and health is very complex, and there is plenty of room to argue cause versus effect and relative impact even in deceptively simple associations such as these. The data showing these associations is robust, however, and here is another example:
[Economists] crunched the numbers and found that the richer you are, the longer you'll live. [They] parsed this data from the University of Michigan's Health and Retirement Study, a survey that tracks the health and work-life of 26,000 Americans as they age and retire. The data is especially valuable as it tracks the same individuals every two years in what's known as a longitudinal study, to see how their lives unfold.
The good news is that men of all incomes are living longer. Yet the data shows that the life expectancy of the wealthy is growing much faster than the life expectancy of the poor. Here's the sort of detail this remarkable data set can show. You can look at a man born in 1940 and see that during the 1980s, the mid-point of his career, his income was in the top 10% for his age group. If that man lives to age 55 he can expect to live an additional 34.9 years, or to the age of 89.9. That's six years longer than a man whose career followed the same arc, but who was born in 1920. For men who were in the poorest 10%, they can expect to live another 24 years, only a year and a half longer than his 1920s counterpart.
The story is rather different for women. At every income level, for both those born in 1920 and 1940, women live longer than men. But for women, the longevity and income trends are even more striking. While the wealthiest women from the 1940s are living longer, the poorest 40% are seeing life expectancy decline from the previous generation. "At the bottom of the distribution, life is not improving rapidly for women anymore. Smoking stands out as a possibility. It's much more common among women at lower income levels."