Evolutionary mismatch is now recognized as affecting many aspects of modern life; examples include diet, exercise, light exposure, chronic stress, sleep deprivation, electronic technology, drug abuse, mental health, spousal abuse, climate change, social inequity, politics, and economics1, 2, 3, 4, 5, 6, 7, 8, 9. It also has many implications for Public Health, often resulting in unnecessary suffering and death. The controversy surrounding vaccination is just one such example.
Vaccines have been undeniably successful at preventing many of the most dreaded and fatal diseases and represent one of the most important health discoveries ever made. One has to look no further than the eradication of smallpox, protection against polio, and the dramatically lower rates of many previously common diseases (e.g., measles, mumps, rubella, cholera, yellow fever) to appreciate their importance.
I hypothesize that the current anti-vaccination movement is a result, in part, of the innate cognitive biases inherent in our nervous systems that evolved to deal with problems in a very different premodern world. While such largely unconscious biases worked well for our distant ancestors in their environmental context, they are ill-suited to novel modern circumstances. Two such biases that today result in people making objectively irrational decisions are “discounting the future” and “loss aversion.”
“Discounting the future” makes us more likely to value immediate rewards over future benefits, and was on average beneficial to hunter-gatherers (e.g., it was best to drink and eat while water and food were available). However, today humans are faced with longer lives complicated by rapid cultural evolution. Ignoring Public Health interventions such as vaccinations (or stopping smoking, etc.) that greatly reduce future morbidity and mortality can only be described as irrational.
“Loss aversion” (the tendency to strongly prefer avoiding losses relative to acquiring gains) made sense in the ancestral context because it was better to err on the side of caution when dealing with predators, since a loss might mean death. Today this bias results in irrational decisions with people often avoiding even very minor “risks” (e.g., low probability of allergic reactions or slight inconvenience such as minor pain of an injection) rather than opting for a far greater likely gain (protection from serious disease).
Likewise, humans evolved to respond most strongly to immediate threats or clear and present danger (e.g., predator attack) but not so strongly to something more remote that might or might not occur (e.g., infection by a fatal disease). Considering this perspective, vaccines that protect against potentially catastrophic but temporally or spatially remote and unfamiliar illnesses often do not generate a response proportional to their true benefit. In the modern context such biases predispose us to irrational decisions that can result in individuals or their loved ones having higher rates of avoidable disease or death.
Cognitive biases also interact with cultural mismatches in the anti-vaccine movement. Consider the opposition by some religious groups and politicians to vaccination against human papillomavirus (HPV) because of the fear of promiscuity. People can easily fall into the trap of “in-group” versus “out-group” or “us versus them” cognitive bias. Subsequently, once a party or religion or other group “decides” what is “correct,” there are psychological and social consequences (e.g., ostracism, expulsion from the group, loss of reputation) for individuals that go against the group mentality. This can lead to individuals making choices that ultimately cause harm to themselves and others. Thus, affiliation with a religion or political party that advocates ideas harmful to group members becomes an example of cultural mismatch. This is especially tragic in the case of HPV where the vaccine is now known to reduce cervical cancer risk (as well as the risk of throat and mouth cancer) and those not taking the vaccine have a much greater risk of unnecessary suffering and death.
How does one address these types of mismatch? The only approaches likely to succeed are those that consider both our inherent strengths and innate weaknesses, and that apply appropriate techniques to change minds and ultimately policies. Such strategies that have been suggested and sometimes applied in other fields (e.g., Behavioral Economics or in countering climate change denial) include: increasing awareness of our cognitive biases; improving choice architecture (i.e., design ways in which choices are presented to increase the probability of desirable outcomes); framing topics differently (e.g., focusing on what can be gained versus lost); encouraging people to contemplate the question, “What if I’m wrong?”; leveraging relevant social group norms; and minimizing time discounting and present bias (e.g., help people connect with their future selves or descendants)10, 11.
- Lloyd, E., Wilson, D.S., & Sober, E. (2011). Evolutionary mismatch and what to do about it: A basic tutorial. Available at: https://evolution-institute.org/wp-content/uploads/2015/08/Mismatch-Sept-24-2011.pdf.
- Eaton, S.B., Konner, M., & Shostak, M. (1988). Stone agers in the fast lane: Chronic degenerative diseases in evolutionary perspective. American Journal of Medicine 84(4):739-749.
- Lieberman, D.E. (2013). The story of the human body: Evolution, health, and disease. New York: Pantheon Books Inc.
- Logan, A.C. & Jacka, F.N. (2014). Nutritional psychiatry research: An emerging discipline and its intersection with global urbanization, environmental challenges and the evolutionary mismatch. Journal of Physiological Anthropology. 33(1):22. doi: 10.1186/1880-6805-33-22.
- Pani, L. (2000). Is there an evolutionary mismatch between the normal physiology of the human dopaminergic system and current environmental conditions in industrialized countries? Molecular Psychiatry 5(5):467-475.
- Diggs, G.M. (2017). Evolutionary mismatch: Implications far beyond diet and exercise. Journal of Evolution and Heath 2(1):3. doi: 10.15310/2334-3591.1057.
- Thaler, R.H. & Sustein, C.R. (2008). Nudge: Improving decisions about health, wealth, and happiness. New Haven: Yale Univ. Press.
- Kahneman, D. (2011). Thinking, fast and slow. New York: Farrar, Straus & Giroux.
- Gifford, R. (2011). The dragons of inaction: Psychological barriers that limit climate change mitigation and adaptation. American Psychologist 66(4):290-302.
- van der Linden, S., Maibach, E., & Leiserowitz, A. (2015). Improving public engagement with climate change: Five “best practice” insights from psychological science. Perspectives on Psychological Science 10:758-763.
- Ross, L., Arrow, K., Cialdini, R., Diamond-Smith, N., Diamond, J., Dunne, J., Feldman, M., Horn, R., Kennedy, D., Murphy, C., Pirages, D., Smith, K., York, R., & Ehrlich, P. (2016). The climate change challenge and barriers to the exercise of foresight intelligence. BioScience 66(5):363-370.