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

Abstract

Culture–gene coevolutionary theory posits that cultural values have evolved, are adaptive and influence the social and physical environments under which genetic selection operates. Here, we examined the association between cultural values of individualism–collectivism and allelic frequency of the serotonin transporter functional polymorphism (5-HTTLPR) as well as the role this culture–gene association may play in explaining global variability in prevalence of pathogens and affective disorders. We found evidence that collectivistic cultures were significantly more likely to comprise individuals carrying the short (S) allele of the 5-HTTLPR across 29 nations. Results further show that historical pathogen prevalence predicts cultural variability in individualism–collectivism owing to genetic selection of the S allele. Additionally, cultural values and frequency of S allele carriers negatively predict global prevalence of anxiety and mood disorder. Finally, mediation analyses further indicate that increased frequency of S allele carriers predicted decreased anxiety and mood disorder prevalence owing to increased collectivistic cultural values. Taken together, our findings suggest culture–gene coevolution between allelic frequency of 5-HTTLPR and cultural values of individualism–collectivism and support the notion that cultural values buffer genetically susceptible populations from increased prevalence of affective disorders. Implications of the current findings for understanding culture–gene coevolution of human brain and behaviour as well as how this coevolutionary process may contribute to global variation in pathogen prevalence and epidemiology of affective disorders, such as anxiety and depression, are discussed.

The cultural contagion of conflict

“…Hence, population variation in allelic frequency may similarly be associated with cultural traits, such as intergroup conflict contagion, although the functional significance of this population allelic frequency variation is not yet well understood and may arise owing to neutral as well as natural selection forces [54,59,63]. More specifically, increased costly punishment within collectivistic societies may arise from culture-gene coevolution, whereby population frequency variation of both the OXTR and COMT functional polymorphisms, which differ between collectivistic and individualistic nations, lead to differential selection or favourability of the cultural trait of costly punishment across cultures.…”

“…Population allelic frequency variation is apparent in a number of genetic functional polymorphisms important to social behaviour [54,59]. For instance, in a typical Western population, the G allele of the OXTR and the VAL allele of the COMT [57] are typically associated with empathy and prosociality, respectively.…”

“…Remarkably, a recent study by De Dreu et al [60] found that participants who were given self-administered oxytocin showed increased ingroup bias or favouritism, demonstrating for the first time a causal biological mechanism between the neuropeptide oxytocin and ingroup favouritism, a precursor to intergroup conflict. Notably, variation in allelic frequency of the serotonin transporter gene (5-HTTLPR) has recently been associated with cultural traits of individualism and collectivism [54]. By extension, allelic frequency for both the G/A alleles of the OXTR gene and the VAL/MET alleles of the COMT gene are known to vary between Western and East Asian populations [61,62].…”

“…According to culture-gene coevolutionary theory, cultural traits, such as individualism and collectivism, have an adaptive benefit, either to the individual or group, and will be selected for via genetic selection whereby genes that facilitate the generation and transmission of these cultural traits will become more prevalent within a given group [53,54]. One tractable hypothesis is that costly punishment against outgroups may have evolved more in collectivistic compared with individualistic cultures owing to the adaptive nature of this cultural trait and may arise from genes that have been selected for within these cultural contexts to foster associated behavioural phenotypes, such as exerting pain on or withholding rewards from outgroup members, even at the expense to one's self.…”

Communicated somatic markers benefit both the individual and the species

“…Recent studies have begun to understand social behaviors at a genetic level through coevolution [11]. Future work should consider the coevolution of somatic markers within a social model such as the one presented in this work.…”