1. Human Cultural Adaptation? Has infectious disease influenced collectivism, language diversity, and religious diversity?

2. Cultural Evolution Novel cultural traits Transmission via social learning Culture can evolve Cultural traditions might impact survival/fecundity Trait advances; culture adapts

3. Pathogens: Selective Pressures “appear to influence” primate psychology and social behavior Fincher at al. 2008. Proc. Roy. Soc. B275:1279-1285 ask: Possible ethnocentrism, xenophobia, prejudice reflect avoidance of novel pathogens?

4. Pathogens and Human Culture Patterns among cultures: Prevalence of disease-causing pathogens And Food preparation Marriage structures Mate preferences Parenting

5. Pathogens and Human Culture Fincher et al (2008) focus: Disease prevalence (historical) and Individualism/collectivism cultural values Consider “cultural-summary traits” Ask how might differ as disease prevalence varies

6. Individualism-collectivism Individualistic cultures people as independent of each other encourage self-expression, personal goals Collectivist cultures social harmony important conformism

7. Individualism-collectivism: Chiao & Blizinsky (2010) Proc. Roy. Soc. B277: 529-537 Gray: no data; High score: collectivism

8. Chiao & Blizinsky (2010) Proc. Roy. Soc. B277: 529-537

9. Pathogens: Individualism, collectivism Collectivism: 1) Stronger distinction, in-group vs out-group 2) Stronger conformity, value of tradition 1.Collectivism: reduced exposure to novel pathogens? 2. Collectivism: tradition (food preparation) more likely to inhibit infection transmission?

10. Fincher at al. 2008. Proc. Roy. Soc. B275:1279-1285 Collectivists: Distinguish in-group vs out-group Response a (cultural) adaptation to greater prevalence of pathogen infection? Score cultures by collectivism and individualism Score regions/cultures by pathogen prevalence (?) leishmania, trypanosomes, malaria, filariae, leprosy, dengue, typhus & tuberculosis

11. Fincher at al. 2008. Proc. Roy. Soc. B275:1279-1285 “Measure” individualism vs collectivism Surveys 100,000 IBM employees worldwide 17,300 Individuals (GLOBE)

12. Fincher at al. 2008. Proc. Roy. Soc. B275:1279-1285

14. Given the authors’ analysis, we cannot reject the hypothesis of no relationship between estimated historical prevalence of 9 pathogens and contemporary collectivism score.

15. Pathogens and Language Diversity Fincher and Thornhill. 2008. Oikos 117:1289-1297 Disease Richness And Language Diversity

16. Pathogens and Language Diversity Suppose local host-parasite coevolution Spatial variation in immunity ecotypes Positive assortative sociality Reduce exposure to novel pathogens (not adapted) Reduced dispersal/migration Cultural isolation  Language proliferation

17. Background Birds: Increased dispersal distance  More responsive, costly immune system Dispersers encounter novel pathogens

18. Background Primates: Savannah vs Rain forest Savannah: Greater movement between groups Different groups share protozoan parasites Infections: Low virulence Low virulence: Weak selection against mixing

19. Background Primates: Savannah vs Rain forest Rain forest: Little movement between groups Among-group variation in parasites Virulent infections Authors: Local immunotypes selected maintained by reduced dispersal

20. Human Immun-ecotypes If local host-parasite differentiation Low dispersal, high social assortment Similar behavioral norms Similar adornment, values, religion Similar MHC (?) Similar language Within-group mating

21. Fincher and Thornhill (2008) Hypothesis: Greater pathogen richness Greater cultural isolation (to avoid novel disease) Greater language diversity

22. Fincher and Thornhill (2008) GIDEON Parasite richness/country Mean = 201 =+/- 25 ETHNOLOGUE Indigenous languages/country Mean = 38 +/- 34

23. Ln(Languages) increases with diseases

24. Fincher and Thornhill (2008): Correlations

25. Fincher and Thornhill. 2008. Given authors’ analysis, we cannot reject hypothesis of no relationship between the number of parasites (infectious diseases) per country and the number of indigenous languages per country.

26. Fincher and Thornhill. 2008. Proc. Roy. Soc. B 275:2587-2594 Reapply the pathogen-language argument to pathogen diversity – religious diversity Religion as ethnic marker: Sign of commitment/membership to single group similarly committed individuals

27. Fincher and Thornhill. 2008. Proc. Roy. Soc. B 275:2587-2594 Religion richness (219 countries) Mean = 30.8 +/- 69.4 Range: 3 to 643 Religions more numerous in tropics than temperate zones

28. Fincher and Thornhill. 2008. Proc. Roy. Soc. B 275:2587-2594

29. Correlations: Religion Number/Country