Why Zebras Don't Get Ulcers: A Guide to Stress, Stress Related Diseases, and Coping

Sapolsky shifts focus to address the impact that social status has on stress and health. Unlike in the discussions of other topics, in which animal studies provide simplified views of complex behaviors, in the discussion on the implications of social status, non-human primates demonstrate more complexity. Subordinate male baboons who experience more harassment typically have high glucocorticoid levels, poor health, and inefficient stress-responses for short-term stress. Studies show that social rank precedes the biological outcomes, eliminating the idea that those with high glucocorticoids naturally become lower ranking.

This phenomenon does not appear in all species or social groups. In some groups, subordinate members have lower levels of glucocorticoids and stress-related health concerns than dominant members. In primates, the difference is based on harassment rates and levels of social support. If dominant individuals are too busy to harass lower-level members or if the dominance hierarchy is unstable, then the lower-ranking animals have lower glucocorticoid levels. The personality of the primates also plays a role in how their social status impacts their stress levels.

Studies on human dominance are somewhat unreliable and irrelevant as there is no consistent definition of human dominance. Additional complications arise from the ideas that pre-agricultural humans were likely egalitarian, that people can hold multiple ranks, and people’s perceptions of rank vary. The exception to these complications is financial status. Low socioeconomic status (SES) is accompanied by numerous physical, psychological, and social stressors, few resources and coping mechanisms, and a lack of social support. Studies have found that low-SES is associated with chronic stress and elevated glucocorticoid levels in children as young as six years old.

Poverty is the most significant behavioral risk factor for contracting diseases, and individuals with a low-SES typically have a reduced life expectancy. Studies show that poverty precedes the development of diseases, ruling out the idea that poor health precedes low-SES. Not only do low-SES individuals have less access to quality health insurance, but they also receive biased treatment from medical professionals. However, the SES health gradient occurs in countries with socialized health care, and it occurs with diseases where access to health care is irrelevant, showing that access to health care is not a significant cause of the gradient. Individuals with a low-SES are more prone to have a poor education, to have unhealthy diets, and to engage in unhealthy behaviors like smoking and not exercising. These trends, like health care access, are not the primary driver of the SES health gradient.

Since the book was first published, new information on the SES-health gradient has emerged, prompting Sapolsky to update the text. New findings show that feeling poor relative to peers is a significant driver of the SES-health gradient. Researcher Nancy Adler asked people to rank their social positions, and their self-rankings correlated with their health. Societies with more financial inequality experience worse health and higher mortality rates, and while one’s immediate community seems to have the largest impact on perceived SES, modern society, with its communication advances like social media, extend one’s immediate community.

In countries with more inequality, both wealthy and poor individuals experience worse health compared to egalitarian nations. Income inequality is linked to low social capital—social resources like trust, peace, and participation—and is linked to increased social stressors, like crime. Low-SES individuals face additional disadvantages, as wealthy individuals are less willing to invest in social services. Low-SES individuals are stressed living in a low-resource society, and high-SES individuals experience stress from trying to seclude themselves from society. The SES gap in the United States is immense, the social capital is low, due to the high level of anonymity and ability to move locations, and the SES health gradient is steep.

Other primates’ risk of stress-related diseases depends on a variety of social factors. In humans, low-SES individuals, despite other social factors, experience universally poorer health. Sapolsky posits that agriculture and the societal changes it brought about was the catalyst for this discrepancy between humans and nonhuman primates. Agriculture led to unequal resource distribution and the development of poverty.

Stress has negative health consequences, but there is hope. Drawing attention to the variability of health measures in elderly individuals, Sapolsky notes that a percentage of the population remains healthy and that some health factors improve with age. Aging rats with unimpaired memory capabilities have normal glucocorticoid rates and hippocampal mass, and further studies showed that these rats had been frequently and gently handled when young. In human studies, successful aging is correlated with lifelong healthy habits, stable marriages, resiliency, and a sense of being respected and needed.

In a 1960s study on stress in parents of children with cancer, parents who reframed their anxiety, who denied the chances of relapse after remission, and who perceived the cancer as a test from God had lower glucocorticoid levels. Other studies on dogs and humans have shown that perceived levels of control result in resistance to learned helplessness. Sapolsky returns to baboons like Kevin with low glucocorticoid levels. He asserts that these baboons remain in high-ranking positions for longer, continue to enjoy platonic friendships, and remain with their troops, while males with high glucocorticoids are subject to increasing rates of harassment as they age, often driving them to leave the troop.

People with personalities associated with high stress levels can develop healthy coping skills that implement social support, predictability, frustration outlets, and control. Examples include patients who were given control over their pain medication reported less pain and used less pain medication, while nursing home patients given control over their daily activities had improved moods. Other studies on nursing home patients showed better health outcomes when patients were given control over when and how they were moved to another facility. Patients predicably visited by students saw greater benefits than those who received unpredictable or no visits.

Stress management is not as simple as gaining control and predictability, and reducing stress management to simplistic terms can be patronizing. Returning to the study on parents of children with cancer, Sapolsky notes that when the children in the studies came out of remission and died, the parents who had experienced denial now had higher levels of glucocorticoids than those who had persistent anxiety. In the study on the benefits of student visits for nursing home patients, the patients saw a sharp rise in stress after the visits stopped.

Potential coping mechanisms include exercise, meditation, predictability and control, social support, and religion and spirituality. Exercise lowers one’s risk of cardiovascular and metabolic diseases, boosts mood, and may reduce the stress-response. However, the mood boost is temporary, and the exercise must be performed regularly and willingly. Regular meditation can mitigate stress, but the benefits may be constrained to the immediate practice. Studying the long-term benefits is difficult, as studies examine the differences between people who choose whether to meditate, so measured benefits cannot be explicitly linked to the meditation practice as other personality or lifestyle factors cannot be eliminated.

Achieving the right balance of predictability and control can be difficult, and these methods can potentially increase stress. For more severe stressors, a sense of control often intensifies stress. “John Henryism,” named after the folk hero John Henry who died after racing a steam drill, occurs when someone believes that, with hard work, they can conquer anything. John Henryism has mild impacts on privileged individuals, but it is correlated with cardiovascular disease and high blood pressure in those who are uneducated, oppressed, or living in poverty.

Similarly, not all social interactions are stress-reducing. Bad relationships can cause undue stress, and close-knit communities can often be exclusionary. While getting support from one’s social circle is beneficial, it is also beneficial to give support to others: “In a world of stressful lack of control, an amazing source of control we all have is the ability to make the world a better place, one act at a time” (407).

Religion and spirituality offer stress-reducing benefits, although the topic is controversial given the sensitive and personal nature of belief systems. Sapolsky shares that he is an atheist but wishes that he could experience religiosity. Studies on the impact of religion and spirituality have complications: They are usually retrospective, which decreases their reliability, and the complex and pervasive nature of belief systems makes it difficult to attribute results specifically to the subjects’ beliefs. After controlling for lifestyle and other factors, religiosity is correlated with better health, although the health benefits are further impacted by the type of deity individuals believe in. Omnipotent deities offer a stronger sense of control, which helps lower stress. In some instances, however, religiosity can lower one’s mental and physical health.

Cognitive flexibility, or the ability to select the right stress coping mechanism for the situation, offers the most stress-reducing benefits, as does the ability to switch between internal and external loci of control. Sapolsky presents what he calls a “half-baked” idea: He suggests that the goal is to proactively experience an “energized calm,” rather than attempting to avoid stress as much as possible, and to achieve an equilibrium while experiencing moments of intense stress. The 80/20 rule is a general ratio of cause and effect, and Sapolsky suggests it applies to stress management, where 80 percept of stress management occurs with the first 20% of coping mechanism application. Change can only happen if the individual decides to actually change.

Sapolsky encourages readers to practice imperfect and constant stress management, rather than waiting for the “perfect” coping mechanism or the most convenient time. He recaps: Find balance between hope and denial and between perceptions of controlled and uncontrolled stressors; seek predictable information unless the information is likely to become a stressor; find regular and healthy outlets for frustration; and develop a strong social support network.

Stress-related diseases cannot be overcome with a positive mindset, as they require medical science. However, some diseases may be prevented through proper stress management. If human intelligence allows people to invent stressors, then human intelligence can also help individuals manage their stress.