Overview
This lecture explores the science of stress, its origins, physiological impacts, links to social hierarchy, and the consequences for human health and society, drawing on studies of both primates and humans.
The Nature and Purpose of Stress
- Stress evolved as a short-term survival mechanism for crises in mammals.
- In modern life, humans trigger the stress response for psychological threats, resulting in chronic activation.
Biological Mechanisms of Stress
- The stress response is driven by hormones like adrenaline (epinephrine) and glucocorticoids from the adrenal gland.
- Stress increases heart rate, blood pressure, and temporarily suppresses non-essential systems like the immune and reproductive systems.
Stress and Social Hierarchy
- Studies in baboons show lower social rank correlates with higher stress hormones and worse health.
- The Whitehall study in British civil servants found that lower job rank is linked with higher disease risk and lower life expectancy, independent of access to healthcare.
Stress and Physical Health
- Chronic stress can damage the body, including clogged arteries, increased abdominal fat, and weakened immune function.
- Stress can shrink the hippocampus, the brain region central to memory.
- Subordinate primates and low-status humans have higher rates of cardiovascular disease and depression.
The Role of Early Life Stress
- Prenatal and early childhood stress can have lifelong health effects, as seen in the Dutch Hunger Winter study.
- Early stress can alter brain chemistry, fat distribution, and vulnerability to psychiatric disorders.
Cellular and Genetic Effects of Stress
- Chronic stress accelerates the shortening of telomeres (chromosome end-caps), advancing cellular aging.
- Stressed caregivers of chronically ill children showed significantly shortened telomeres, reflecting years of accelerated aging.
Reducing Stress and Social Solutions
- Social affiliation, support, and compassion can promote resilience and may even activate telomerase to repair telomeres.
- Organizational changes like increasing workplace control, fairness, and involvement can reduce stress and improve health.
- Baboon troop studies suggest that social culture can shift from aggression to cooperation, reducing collective stress.
Key Terms & Definitions
- Adrenaline/Epinephrine — Hormone released during stress, increasing heart rate and energy.
- Glucocorticoids — Stress hormones from the adrenal gland, important in the stress response.
- Hierarchy — Social ranking order within a group, affecting access to resources and stress levels.
- Telomeres — Protective caps on chromosomes that shorten with age and stress.
- Telomerase — Enzyme that repairs and lengthens telomeres.
- Hippocampus — Brain region involved in memory, vulnerable to stress-induced damage.
Action Items / Next Steps
- Reflect on personal stressors and consider ways to increase control and social support in daily life.
- Recommended reading: Explore further resources on stress reduction techniques and maintaining a balanced lifestyle.
- Consider implementing stress management strategies, such as mindfulness, humor, and social connection.