Have you ever been “stressed out” in class? Say you’re in a large lecture hall with a hundred other people, or even in a small class where you don’t know anyone. You’re not sure about something the professor just said and you would really like to ask about it, so you start to raise your hand. Does your heart begin to pound and your mouth become dry? Do you get so nervous that you choose to ask a classmate after lecture instead? If so, you are not alone. Fear of speaking in public is one of the most common social phobias (APA 2013). It has been estimated that 75% of all people experience some degree of anxiety or nervousness when it comes to public speaking (Hamilton 2011), and surveys have shown that most people fear public speaking more than they fear death (Croston 2012).
We have evolution to thank for this.
Humans, like other primates, are social animals. Being part of a group helped us to survive predation, get enough to eat, and successfully raise our young. When faced with standing up in front of a group, or even speaking up in class, we break into a sweat because we are afraid of rejection. Psychologist Glenn Croston (2012) writes, “The fear is so great because we are not merely afraid of being embarrassed or judged. We are afraid of being rejected from the social group, ostracized and left to defend ourselves all on our own. We fear ostracism still so much today it seems, fearing it more than death, because not so long ago getting kicked out of the group probably really was a death sentence.” Hence, it is no surprise that public speaking triggers a stress response among much of humankind.
The human nervous system evolved in a context where quick responses to perceived threats presented an evolutionary advantage. The “fight or flight” response was honed during millions of years when threats more often took the form of an approaching lion than an approaching deadline. Our body’s stress response, however, is triggered by a wide variety of stressors that produce the same general pattern of hormonal and physiological adjustments (Martini et al. 2013). In today’s world, the system is often stuck in the “on” position due to the constant pressures of modern life, and this is a significant influence on health and disease.
It is important to recognize that there are different types of stress and the time in life when adult coping mechanisms are formed is in childhood. In children, some stressors can be positive—for example, stressors that are mild to moderate in magnitude, and accompanied by the support of a caring adult, which help children develop pathways by which stress is dealt with by the body throughout life. In a young child, a positive stress response might be going to the pediatrician to receive a vaccination and receiving encouragement and comfort from both parent and practitioner. A tolerable stress response is more serious, precipitated by something like a divorce or death of a relative. Again, buffered by positive support from surrounding adults, these types of stressors can be successfully managed by children. Toxic stress, however, “results from strong, frequent or prolonged activation of the stress response in the absence of the buffering protection of a supportive adult relationship” (Shonkoff and Garner 2012). Examples include child abuse or neglect, parental substance abuse, homelessness, and violence. In the absence of adequate psychological and physical support, the biological pathways of a child’s physiological stress response are altered and lead to reduced abilities to cope with life’s challenges as an adult.
The negative effects of sustained, elevated cortisol levels on health are well documented. These include higher levels of infectious disease and slowed growth in childhood (Flinn and England 2003) and increased incidence of heart disease, obesity, and diabetes in adults (Worthman and Kuzara 2005). Contrary to our evolutionary past, many causes of sustained stress in contemporary societies are psychosocial rather than physical threats. These can include an unhappy marriage or frustrations at work (Dimsdale 2008). Stressors can also be more subtle. For example, a review of research into the effects of stress on health indicated that experiencing racism was a significant stressor that was associated with alcohol consumption, psychological distress, overweight, abdominal obesity, and higher fasting-glucose levels among minority groups (Williams and Mohammed 2013). Chronic, everyday racial discrimination is also associated with the hardening of coronary arteries, elevated blood pressure, giving birth to lower-birth-weight infants, cognitive impairment, poor sleep, and visceral fat, which is fat stored deep inside the belly, wrapped around the organs, including the liver and intestines. Visceral fat is a sign of metabolic syndrome, increasing the risk of stroke, heart disease, and type 2 diabetes. These effects have been shown to increase morbidity and mortality among members of affected groups.
Epigenetics can also be a factor in how a person is able to deal with stressful situations. Maternal experiences of stress during pregnancy have the potential to permanently alter the physiology of mothers’ offspring, especially the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis regulates metabolism, blood pressure, and the immune response, and these alterations can predispose prenatally stressed individuals to suffer metabolic, cardiovascular, and mental disorders in adulthood (Palma-Gudiel et al. 2015). These experiences carry across generations, with children of Holocaust survivors who experienced PTSD demonstrating similar changes in neurochemistry in the absence of a sustained, traumatic event, as did infant offspring of mothers who developed PTSD during pregnancy after witnessing the traumatic events of 9/11 (Yehuda and LeDoux 2007).
