1. Parasite Stress Theory
Frederick Baker
Middle Georgia State University
2/27/2016

2. Parasitic Infection
Parasites - an organism that lives in or on another organism (its host) and benefits by deriving nutrients at the host's expense.
Fumagalli et al. (2011) found in their study of 55 human populations that genes involved in immunity experience significantly more change than genes dealing with 13 other environmental challenges.
Furthermore, infectious diseases caused by parasites were a major source of morbidity across human evolutionary history. (Anderson and Mat 991; Ewald 994; Dobson and Carper 1996; McNeill 1998; Wolfe et al. 2007; Volk and Atkinson 2013)
Malaria among red blood cells.

3. The Physical Effects of Parasites
Two Cliff Swallows
A social species that nests together in large groups in mud nests on the sides of cliifs.
Both of these birds are the same age at a few weeks old.
The bird on the right lived in a nest that was treated for parasites.
The bird on the left was not

4. Classical Immune System
Parasite Stress Model
Classical Immune System

5. Behavioral Immune System
Parasite Stress Model
Behavioral Immune System

6. Immune System(s)
Classical Immune System – The physiological, cellular, and tissue- based mechanisms of defense against parasites.
Behavioral Immune System – The psychology and behavior for infectious disease avoidance (Schaller and Duncan 2007) as well as for managing the effects of diseases when they strike (Fincher and Thornhill 2008a).

7. These behaviors are ancestrally adaptive feelings including:
Disgust
Specific Cognitions (Worry about contagion)
Values and behavior towards in-group and out-group members
Prejudice against people who are perceived as unhealthy, contaminated and unclean.
Prejudice also extends to people with symptoms of noncontagious disease, the physically and mentally handicapped, extra-thin and obese people, the elderly, homosexuals, and other sexual behaviors considered by some societies to be deviant.

8. Individualism - Collectivism
Values the role of the individual a view of the self that is separate from the group.
A weaker group distinction.
Greater tolerance of deviance from norms.
More open and extroverted.
Politically liberal.
Values in group and an intradependent identity.
Strong division between in-group and out-group status.
Places value on group norms and traditions.
Less open to experience and more introverted
Politically conservative.
Triandis (1995)
Oooooop
the surrounding society.

9. Hypothesis
We suggest that specific behavioral manifestations of collectivism (e.g. ethnocentrism, conformity) can inhibit the transmission of pathogens; and so we hypothesize that collectivism (compared with individualism) will more often characterize cultures in regions that have historically had higher prevalence of pathogens. ( Fincher et al )

10. Measurements of Individualism/Collectivism
Hofstede (2001) – Assessed Attitudes and Values from over 100,000 IBM employees from 68 specific geopolitical regions.
Suh et al. (1998) – An index created from combining Hofstede’s database (2001) and numerical ratings from Harry C. Triandis. (1995)
Collectivism
Gelfand et al. (2004) – Measured scores from the “in-group collectivism practices” analysis from the “Global Leadership and Organizational Behavior Effectiveness Research program,” covering 17,370 individuals from 57 regions.
Kashima & Kashima (1998) – Reported cultural value differences reflected by a simple linguistic convention: Whether or not it’s acceptable to drop first and second –person pronouns in spoken language over 70 regions; most common in collectivistic cultures.

11. Measurement of Parasite Stress
Historical
Measured 9 pathogens: Tuberculosis (National Geographic Society 2005), Leishmanias, trypanosomes, malaria, schistosomes, filariae, leprosy, dengue, and typhus (Summons et al. 1944)
Contemporary
Measured the prevalence of 7 pathogens: leishmanias, trypanosomes, malaria, schistosomes,filariae, spirochetes, and leprosy (htttp:// m, April – June 2007)
Both sets of data were coded on 3 or 4 point scales, standardized into z scores, and then averaged together to make means that measure parasite prevalence across regions

12. Data Historical Pathogen Prevalence Pathogen Prevalence Index
Contemporary
Individualism (Hofstede)
- 0.69* (68)
- 0.59* (68)
Individualism (Suh)
- 0.71* (58)
- 0.58* (58)
Collectivism (Gelfand)
0.73* (52)
0.56* (57)
Collectivism (Kashima)
0.63* (70)
0.44* (70)
Historical Pathogen Prevalence
Murdock (1949) 6 world regions
0.93* (6)
Gupta & Hanges (2004) 10 world regions
0.80* (10)

13. Other correlations of parasite stress.
Sociosexuality - Parasite Richness predicts the rate of polygynous unions, where multiple women are married to men who have high access to resources and health. (Low 1988)
Mate choice – Regions with higher rates of parasitic infections place higher importance on physical attractiveness. (Gangestad and Buss 1993)
Personality traits – Extraversion and Openess to experience correlates negatively with both collectivism and parasite stress (Schaller 2008)
Religiosity – Parasite Stress predicts higher levels of religiosity and higher levels of in-group assortiveness among religious and cultural groups. (Thornhill 2010)
A healthy peacock

14. Other theories prior to Parasite Stress Theory
Temperature, Rainfall (Van de Vliert 2008): Parasites thrive in hot and moist ecological settings, and are reduced in colder and drier regions. (Low 1990)
Economic conditions (Lipset 1959; Triandis 1995; Hofstede 2001):
Parasites causes lethargy and morbidity that limit people’s ability to work and produce.
Parasite stress leads to the adoptions of conservative- collectivistic values that would not be as open to new ideas and technologies.
Parasite stress also correlates with lowered cognitive ability.

15. Need for future research
More experimental research is needed:
Activation of the Immune System.
Disgust sensitivity.
Specific diseases (both historical and current) And Stronger Measurements
Black Plague, Small Pox
Zika, Ebola, and HIV
Methods of Transmission
Zoonotic vs. Nonzoonotic
Airborne, Fluids, General Contact
Ebola

16. References
Fincher, C. L., Thornhill, R., Murray, D. R., & Schaller, M. (2008). Pathogen prevalence predicts human cross-cultural variability in individualism/collectivism. Proceedings of the Royal Society of London B: Biological Sciences, 275(1640),
Fincher, C. L., & Thornhill, R. (2008). A parasite‐driven wedge: infectious diseases may explain language and other biodiversity. Oikos, 117(9),
Fumagalli, M., Sironi, M., Pozzoli, U., Ferrer-Admettla, A., Pattini, L., & Nielsen, R. (2011). Signatures of environmental genetic adaptation pinpoint pathogens as the main selective pressure through human evolution. PLoS Genet, 7(11), e
Gangestad, S. W., Haselton, M. G., & Buss, D. M. (2006). Evolutionary foundations of cultural variation: Evoked culture and mate preferences. Psychological Inquiry, 17(2),
Gelfand, M. J., Bhawuk, D. P., Nishii, L. H., & Bechtold, D. J. (2004). Individualism and collectivism. Culture, leadership, and organizations: The GLOBE study of, 62,

17. References
Gupta, V., & Hanges, P. J. (2004). Regional and climate clustering of societal cultures. Culture, leadership, and organizations: The GLOBE study of, 62,
Hofstede, G. H., & Hofstede, G. (2001). Culture's consequences: Comparing values, behaviors, institutions and organizations across nations. Sage.
Kashima, Y., & Kashima, E. S. (2003). Individualism, GNP, Climate, And Pronoun Drop Is Individualism Determined by Affluence and Climate, or Does Language Use Play a Role?. Journal of Cross-Cultural Psychology, 34(1),
Lipset, S. M. (1959). Some social requisites of democracy: Economic development and political legitimacy. American political science review, 53(01),
Low, B. S. (1988). Pathogen stress and polygyny in humans. Human reproductive behavior: A Darwinian perspective, ed. L. Betzig, M. Borgerhoff Mulder & P. Turke,
Murdock, G. P. (1949). Social structure.

18. References
Schaller, M., & Duncan, L. A. (2007). The behavioral immune system: Its evolution and social psychological implications. Evolution and the social mind: Evolutionary psychology and social cognition,
Schaller, M., & Murray, D. R. (2008). Pathogens, personality, and culture: disease prevalence predicts worldwide variability in sociosexuality, extraversion, and openness to experience. Journal of personality and social psychology, 95(1), 212.
Suh, E., Diener, E., Oishi, S., & Triandis, H. C. (1998). The shifting basis of life satisfaction judgments across cultures: Emotions versus norms. Journal of personality and social psychology, 74(2), 4
Triandis, H. C. (1995). Individualism & collectivism. Westview press.
Van de Vliert, E. (2008). Climate, affluence, and culture. Cambridge University Press.