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Key points
- Increased lifespan for the wealthy fits a pattern of high status contributing to better health.
- Long-livers may be more effective at dealing with stress.
- As a person's income rises, their social network tends to get larger.
Life can be very unfair when it comes to health and length of life. When residents of a wealthy U.S. zip code live more than a decade longer than a poorer one, we need to ask why.
Social Status and Health in Other Mammals
Among red deer and other animals, including elephant seals, high-status males do most of the reproducing but pay a significant price to their health from constant aggressive competition. Generally speaking, though, high-status animals (female and male) have priority in access to food, lead low-stress lives, and are healthier. So, one might expect them to lead longer lives. The increased lifespan of high-status humans fits a broader pattern of high status contributing to better health and reproductive success. Could these advantages be the product of genetics?
Genetic Advantages?
Large elephant seal males are better equipped to control a breeding territory and leave more offspring than smaller males. They are larger because large individuals are genetically selected. Among humans, the longer lifespan of wealthy individuals could also be a product of gene selection. The idea is that some individuals have genetic advantages when it comes to health. They are healthier during their lives, live longer, and leave more offspring.
This theory is supported by evidence that longevity is mildly heritable. Presumably those who lead very long lives enjoy unusually good health reflecting a robust immune system and other traits that favor survival, including optimism. Genes can account for approximately one-fifth of variability in longevity.
Are long-livers also better at accumulating wealth and achieving high social status? This idea is often criticized as social Darwinism, but it could be empirically true. So, one-fifth of the differences in life expectancy between rich and poor counties could be explained by social mobility. In other words, individuals who are upwardly mobile compared to the income of their parents also live longer, whether this is due to their genes, or their life experiences.
Long-livers may also be more effective at dealing with stress. This could involve a facility for obtaining social support.
Social Support and Health Behavior
As a person's income rises, their social network tends to get larger. They go out more, meet more people, and are invited to more social events. Such a lifestyle is difficult on a low income.
Having more acquaintances and friends is generally good for our health. When people hug each other, they release oxytocin, a hormone associated with social bonding in humans and other mammals. Oxytocin is an anti-stress agent that protects us from anxiety, depression, and heart disease, among its other health advantages.
In addition to the benefits of a larger social network, affluent people have better health behavior. They are more physically active and have significantly lower levels of obesity. They generally enjoy a healthier diet that contains elements of a Mediterranean diet such as fresh fruits and vegetables that are missing, or scarce, in the diets of poor people who live in food deserts and cannot afford optimal diets.
It is difficult to establish how much a healthy diet affects life expectancy, but research findings range from two years to 10 years. Health behavior could account for several years of the longevity advantage. In addition to enjoying the good things of life, affluent people are less exposed to stressful and toxic environments that can subtract several years from life expectancy.
Diminished Social and Environmental Stressors
There is a long catalog of environmental problems that detract from health. These include psychological stressors, such as noise, heat, violent crime, contact with law enforcement, and separation from parents, as well as physiological challenges such as exposure to lead, dioxin, and toxins from chemical plants.
The Alcohol Conundrum
Affluence is associated with higher alcohol consumption. Yet, alcohol is believed to reduce life expectancy. If so, then presumably the benefits of living in a wealthy zip code more than outweigh the drag from alcohol. As pointed out in an earlier post, alcohol consumption for the wealthy may occur in a positive social context that implies social support in contrast to people who are poor and drink alone.
Residents of wealthy zip codes are better educated than residents of impoverished ones. Having a college education is associated with a life expectancy advantage of two years compared to those with a high-school education.1
Conclusion
The greater life expectancy of wealthy people is complex but can be attributed to different aspects of good fortune, including genetic advantages, increased social support, being more optimistic, and being upwardly mobile. Residents of poor zip codes experience numerous drags on their health and longevity, including greater stress, exposure to crime and environmental pollution, and poor health behavior. These disadvantages are correctable in principle although that is clearly not happening as the health gap seems to be widening.
References
1. Molla, M. T., Madans, J. H., and Wagener, D. K. (2004). Differentials in adult mortality and activity limitation by years of education in the United States at the end of the 1990s. Population and Development Review. 30, 625–646.
