Culture-gene coevolution of individualism-collectivism and the serotonin transporter gene

1. Culture-gene coevolution of individualism-collectivism and the serotonin transporter gene Joan Y. Chiao and Kathrine D. Blizinsky (2009)

2. Introduction • Culture-Gene Coevolution • Cultural traits are adaptive, influencing social and physical environments in which genetic selection takes place • Collectivist vs. Individualist Cultures

3. Area of Serotonin Transporter Gene (5-HTTLPR) • L allele • S allele • Increased negative emotion • (e.g. harm avoidance, heightened anxiety, fear conditioning, attentional bias to negative information and increased risk of depression)

4. Global Distribution of the “S” allele (red = most prevalent)

5. Disease Causing Pathogens? • Increased incidence of Mood & Anxiety Disorders in East Asia… NO!

6. Our Hypothesis… • Differences in serotonin production are caused by culture-gene coevolution, and serve an adaptive function in collectivist cultures to protect against environmental stress. • What is the relationship between the serotonin gene, individualism-collectivism and prevalence of disease causing pathogens across nations?

7. Material and Methods 1. Cross-national sample of allelic frequency of 5-HTTLPR 50135 individuals, 29 countries 124 peer-reviewed publications

8. 2. Cross-national sample of cultural values • Hofstede’s published regional scores of individualism-collectivism, 29 nations • Hofstede’s scores of power distance, uncertainty avoidance, masculinity-femininity and long-term orientation, 22 nations

9. 3. Cross-national sample of economic indices • Gross domestic product (GDP) • Gini index • 29 countries

10. 4. Cross-national sample of pathogen prevalence • Contempory and historical pathogen prevalence data

11. 5. Cross-national sample of prevalence of mental health disorders • 2008 WHO Mental Health Surveys report • 12 nations

12. Statistical Analysis • Heterogeneity of sample size • Included all available published data for each variable in the multiple regression and meditation regression analyses

13. Nation as a unit of analysis • Geographical regions defined by nation served as the unit of analyses Correlational analyses also with: • Murdock’s (1949) six world regions • Gupta & Hanges’ (2004) 10 distinct cultural clusters

14. Results Collectivist cultures more likely to have carriers of the short (s) allele of the 5-HTTLPR Individualism-collectivism can be predicted by the historical pathogen prevalence S-allele negatively predicts prevalence of anxiety and mood disorder owing to increased collectivist cultural values of s-allele carriers Suggests a culture-gene co evolution. Cultural values buffer genetically susceptible populations from increased prevalence of mood affective disorders

15. Correlation between individualism-collectivism index and frequency of s-allele carriers- Collectivist nations showed higher prevalence of s-allele carriers

16. Discussion A) There is a “robust” association between cultural values of individualism-collectivism and allelic frequency of the serotonin transporter gene. B) Global pathogen prevalence predicts global variability in individualism-collectivism (and allelic differences). C) There is a surprising and negative association between individualism-collectivism and global prevalence of anxiety disorders.

17. Cultural values serve adaptive functions by tuning societal behaviour so that social and environmental risk factors are reduced and physical and mental health of group members is maintained. • Genetic & Biological links to society and personality.

18. Other Studies of Interest • Stoltenberg et al (2002) “ Serotonin transporter promoter polymorphism, peripheral indexes of serotonin function and personality measures in families with alcoholism” • 5-HTTLPR and platelet 5-HT binding • No relationship between 5-HTTLPR and alcoholism • But is does have a relationship with personality…

19. Other Studies of Interest • Kalbitzer et al (2009) “The personality trait openness is related to cerebral 5-HTT levels • 5-HTT binding in different brain areas • S-allele carriers have lower binding, and lower binding is found in high O individuals • Relates to cognitive flexibility and the ability to adapt to new circumstances

20. Other Studies of Interest • Chen et al (1999) • “Population migration and the variation of dopamine D4 receptor (DRD4) allele frequencies around the globe” • L-allele more prevalent in migratory populations • Adaptive value to the l-allele • Relates to personality (e.g. novelty seeking, exploratory behaviour)

21.  Thank You 