We know that wealth correlates with greater life expectancy. Aging and late-life disease are the consequences of ongoing biological damage, and we might theorize that wealthier people on average have greater means and knowledge to reduce the rate at which that damage occurs - though I believe that knowledge and the will to use it are more important than means. No present day medical technology can do as much for a healthy person as exercise and calorie restriction, available to rich and poor alike. But all in all, we shouldn't be surprised to find statistically significant biological differences between the metabolisms of the wealthy and the poor, reflecting the differences in lifestyle and levels of biological damage: researchers "found evidence that biological ageing is slower among people with better socio-economic circumstances. ... It found that the wealthier people were, the higher their levels of DHEAS. The discovery raises the possibility that the hormone could be artificially produced and used to make people live longer. The scientists also found that those with higher levels of it tended to do greater amounts of exercise, lead a more active life with lots of pastimes, and have more friends and family. ... The research also found higher levels of a second hormone - growth factor I (IGF-I) - in those who are wealthier."