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

serotonin transporter geneserotonin transporter gene

Joan Y. Chiao and Kathrine D. Blizinsky (2009)Joan Y. Chiao and Kathrine D. Blizinsky (2009)

IntroductionIntroduction

Culture-Gene CoevolutionCulture-Gene Coevolution• Cultural traits are adaptive, influencing Cultural traits are adaptive, influencing

social and physical environments in social and physical environments in which genetic selection takes placewhich genetic selection takes place

• Collectivist vs. Individualist CulturesCollectivist vs. Individualist Cultures

Area of Serotonin Transporter Gene (5-Area of Serotonin Transporter Gene (5-HTTLPR)HTTLPR)• L alleleL allele• S alleleS allele

• Increased negative emotion Increased negative emotion (e.g. harm avoidance, heightened anxiety, fear (e.g. harm avoidance, heightened anxiety, fear

conditioning, attentional bias to negative information conditioning, attentional bias to negative information and increased risk of depression)and increased risk of depression)

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

Disease Causing Pathogens?Disease Causing Pathogens?

Increased incidence of Mood & Increased incidence of Mood & Anxiety Disorders in East Asia… NO!Anxiety Disorders in East Asia… NO!

Our Hypothesis…Our Hypothesis…

1)1) Differences in serotonin production are Differences in serotonin production are caused by culture-gene coevolution, and caused by culture-gene coevolution, and serve an adaptive function in collectivist serve an adaptive function in collectivist cultures to protect against environmental cultures to protect against environmental stress.stress.

2)2) What is the relationship between the What is the relationship between the serotonin gene, individualism-serotonin gene, individualism-collectivism and prevalence of disease collectivism and prevalence of disease causing pathogens across nations?causing pathogens across nations?

Material and MethodsMaterial and Methods

1. Cross-national sample of 1. Cross-national sample of allelic frequency of 5-HTTLPRallelic frequency of 5-HTTLPR

50135 individuals, 29 countries50135 individuals, 29 countries124 peer-reviewed publications124 peer-reviewed publications

2. Cross-national sample of cultural 2. Cross-national sample of cultural valuesvalues

Hofstede’s published regional scores of Hofstede’s published regional scores of individualism-collectivism, 29 nationsindividualism-collectivism, 29 nations

Hofstede’s scores of power distance, uncertainty Hofstede’s scores of power distance, uncertainty avoidance, masculinity-femininity and long-term avoidance, masculinity-femininity and long-term orientation, 22 nationsorientation, 22 nations

3. Cross-national sample of economic 3. Cross-national sample of economic indicesindices

Gross domestic product (GDP)Gross domestic product (GDP) Gini indexGini index 29 countries29 countries

4. Cross-national sample of pathogen 4. Cross-national sample of pathogen prevalenceprevalence

Contempory and historical pathogen prevalence Contempory and historical pathogen prevalence datadata

5. Cross-national sample of prevalence 5. Cross-national sample of prevalence of mental health disordersof mental health disorders

2008 WHO Mental Health Surveys report2008 WHO Mental Health Surveys report 12 nations12 nations

Statistical AnalysisStatistical Analysis

Heterogeneity of sample sizeHeterogeneity of sample size Included all available published data for each Included all available published data for each

variable in the multiple regression and meditation variable in the multiple regression and meditation regression analysesregression analyses

Nation as a unit of analysisNation as a unit of analysis

Geographical regions defined by nation Geographical regions defined by nation served as the unit of analysesserved as the unit of analyses

Correlational analyses also with:Correlational analyses also with: Murdock’s (1949) six world regionsMurdock’s (1949) six world regions Gupta & Hanges’ (2004) 10 distinct Gupta & Hanges’ (2004) 10 distinct

cultural clusterscultural clusters

ResultsResults1.1. Collectivist cultures more likely to have Collectivist cultures more likely to have

carriers of the short (s) allele of the 5-carriers of the short (s) allele of the 5-HTTLPR HTTLPR

2.2. Individualism-collectivism can be predicted Individualism-collectivism can be predicted by the historical pathogen prevalenceby the historical pathogen prevalence

3.3. S-allele negatively predicts prevalence of S-allele negatively predicts prevalence of anxiety and mood disorder owing to anxiety and mood disorder owing to increased collectivist cultural values of s-increased collectivist cultural values of s-allele carriersallele carriers

4.4. Suggests a culture-gene co evolution. Suggests a culture-gene co evolution. Cultural values buffer genetically Cultural values buffer genetically susceptible populations from increased susceptible populations from increased prevalence of mood affective disorders prevalence of mood affective disorders

Correlation between individualism-collectivism Correlation between individualism-collectivism index and frequency of s-allele carriers- Collectivist index and frequency of s-allele carriers- Collectivist

nations showed higher prevalence of s-allele nations showed higher prevalence of s-allele carrierscarriers

DiscussionDiscussion

A) There is a “robust” association between cultural A) There is a “robust” association between cultural values of individualism-collectivism and allelic values of individualism-collectivism and allelic frequency of the serotonin transporter gene.frequency of the serotonin transporter gene.

B) Global pathogen prevalence predicts global B) Global pathogen prevalence predicts global variability in individualism-collectivism (and allelic variability in individualism-collectivism (and allelic differences).differences).

C) There is a surprising and negative association C) There is a surprising and negative association between individualism-collectivism and global between individualism-collectivism and global prevalence of anxiety disorders.prevalence of anxiety disorders.

Cultural values serve adaptive functions Cultural values serve adaptive functions by tuning societal behaviour so that social by tuning societal behaviour so that social and environmental risk factors are and environmental risk factors are reduced and physical and mental health of reduced and physical and mental health of group members is maintained.group members is maintained.

Genetic & Biological links to society and Genetic & Biological links to society and personality.personality.

Other Studies of InterestOther Studies of Interest

Stoltenberg et al (2002)Stoltenberg et al (2002)

“ “ Serotonin transporter promoter Serotonin transporter promoter polymorphism, peripheral indexes of polymorphism, peripheral indexes of serotonin function and personality serotonin function and personality measures in families with alcoholism”measures in families with alcoholism”• 5-HTTLPR and platelet 5-HT binding5-HTTLPR and platelet 5-HT binding• No relationship between 5-HTTLPR and alcoholismNo relationship between 5-HTTLPR and alcoholism• But is does have a relationship with personality…But is does have a relationship with personality…

Other Studies of InterestOther Studies of Interest

Kalbitzer et al (2009)Kalbitzer et al (2009)

““The personality trait openness is The personality trait openness is related to cerebral 5-HTT levelsrelated to cerebral 5-HTT levels• 5-HTT binding in different brain areas5-HTT binding in different brain areas• S-allele carriers have lower binding, and S-allele carriers have lower binding, and

lower binding is found in high O lower binding is found in high O individualsindividuals

• Relates to cognitive flexibility and the Relates to cognitive flexibility and the ability to adapt to new circumstancesability to adapt to new circumstances

Other Studies of InterestOther Studies of Interest

Chen et al (1999)Chen et al (1999) ““Population migration and the Population migration and the

variation of dopamine D4 receptor variation of dopamine D4 receptor (DRD4) allele frequencies around the (DRD4) allele frequencies around the globe”globe”• L-allele more prevalent in migratory L-allele more prevalent in migratory

populationspopulations• Adaptive value to the l-alleleAdaptive value to the l-allele• Relates to personality (e.g. novelty seeking, Relates to personality (e.g. novelty seeking,

exploratory behaviour)exploratory behaviour)

Thank You Thank You