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Culture gene coevolution of individualism - collectivism
Dual Inheritance Theory (DIT), also known as Gene-culture coevolution, was developed in the late 1970s and early 1980s to explain how human behavior is a product of two different and interacting evolutionary processes: genetic evolution and cultural evolution. DIT is a “middle-ground” between much of social science, which views culture as the primary cause of human behavioral variation, and human sociobiology and evolutionary psychology which view culture as an insignificant by-product of genetic selection. In DIT, culture is defined as information in human brains that got there by social learning. Cultural evolution is considered a Darwinian selection process that acts on cultural information. Dual Inheritance Theorists often describe this by analogy to genetic evolution, which is a Darwinian selection process acting on genetic information. — (Wikipedia)
“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. (…)
In addition to cultural factors, human behaviour is influenced by specific genes, such as the serotonin transporter gene (SLC6A4), which regulates serotonergic neurotransmission (5-HTT). (…) In particular, exposure to chronic life stress, such as interpersonal conflict, loss or threat, is considered a well-known environmental risk factor for depression in S allele carriers of the 5-HTT. (…) Evidence from population genetics reveals greater population frequency of 5-HTTLPR S allele carriers of the 5-HTTLPR functional polymorphism within certain geographical regions of the world, such as East Asia. In a typical East Asian sample, 70–80% of individuals are S carriers compared with a typical European sample where 40–45% of individuals are S carriers of the 5-HTT genotype. (…)
It remains unclear why there exists genetic selection for S relative to L allele carriers in East Asian regions, but not other geographical regions of the world. One possible explanation for greater prevalence of S allele carriers in East Asia is that geographical variability in environmental pressures has led to cultural variability in individualism–collectivism via genetic selection. Recent research has shown that geographical variability in historical and contemporary pathogen prevalence predicts variability in individualistic and collectivistic cultural norms. That is, nations with greater historical and contemporary prevalence of disease-causing pathogens or infectious diseases (e.g. malaria, typhus and leprosy) are more likely to endorse collectivistic cultural norms, likely due to the anti-pathogen defence function that collectivistic norms may serve. Given the adaptive value of collectivistic cultural values, it is possible that increased pathogen prevalence in East Asian regions may be associated with increased collectivistic values due to genetic selection of the S allele of the serotonin transporter gene within collectivistic cultures. (…)
On the contrary, evidence from a number of cross-cultural epidemiological studies indicates that East Asian populations consistently report lower prevalence of negative affect, such as anxiety and mood disorders relative to Western populations. (…)
Culture–gene coevolutionary theory proposes that cultural traits, such as individualism and collectivism, have evolved and are adaptive. Supporting the notion of cultural traits as evolutionary adaptations, recent cross-national evidence shows that cultural values of individualism and collectivism serve an adaptive, ‘anti-pathogen’ function, protecting vulnerable geographical regions from increased spread of disease-causing pathogens via the promotion of collectivistic social norms, such as conformity and parochialism. (…)
Similarly, here we propose that by favouring social harmony over individuality, collectivistic cultural norms may have evolved to also serve an adaptive, ‘anti-psychopathology’ function, creating an environmental niche that reduces the risk of exposure to environmental pathogens, such as chronic life stress, for group members. Consistent with a geneby- environment (GxE) theory of affective disorders, reduced exposure to chronic life stress for individuals living in collectivistic relative to individualistic cultures would then cause reduced prevalence of affective disorders among genetically susceptible individuals. Hence, culture variation in the epidemiological prevalence of anxiety and depression is likely due to geographical variation in the cultural adoption of collectivistic social norms. (…)
Taken together, these results indicate that historical, but not contemporary, pathogen prevalence predicts cultural variability of individualism– collectivism due to increased S allelic frequency of the serotonin transporter gene. (…)
Taken together, these findings dovetail nicely as two examples of how 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. Importantly, in the current study, we found that population frequency of the serotonin transporter gene was a singular predictor of cultural values of individualism–collectivism across nations, even when controlling for historical and contemporary pathogen prevalence. Hence, our findings illustrate that gene frequency plays a unique role in explaining global variation in the adoption of cultural norms and is fundamental to any comprehensive understanding of culture.
A central claim of culture–gene coevolutionary theory is that once cultural traits are adaptive, it is likely that genetic selection causes refinement of the cognitive and neural architecture responsible for the storage and transmission of those cultural capacities. (…)
Recent behavioural evidence indicates that individuals carrying the S allele exhibit stronger attentional bias for negative words and pictures whereas individuals carrying the Lallele demonstrate a stronger attentional bias towards positive pictures and away from negative pictures. By extension, S allele carriers may be more likely to demonstrate negative cognitive biases, such as engage in narrow thinking and cognitive focus, which facilitate maintenance to collectivistic cultural norms of social conformity and interdependence, whereas L allele carriers may exhibit positive cognitive biases, such as open, creative thinking and greater willingness to take risks, which promote individualistic cultural norms of self-expression and autonomy. (…)
Neural activity within brain regions innervated by serotonergic neural pathways, such as the human amygdala, may serve as another likely information processing mechanism involved in the storage and transmission of cultural values of individualism and collectivism. (…)
For people living in collectivistic cultures, heightened selective attention and increased amygdala response to negative information may be advantageous to achieving collectivistic cultural norms, such as maintaining social harmony. For instance, greater vigilance to negative information may be useful for early detection of another person’s anger or fear as well as foreshadowing and avoiding actions or interpersonal situations that may induce negative emotional states in others. Also, greater vigilance to negative information may encourage a stronger narrow thinking and cognitive focus, enabling one to effectively conform to social norms. By contrast, for people living in individualistic cultures, heightened selective attention and increased amygdala response to negative information may be disadvantageous to achieving individualistic cultural norms of self-expression and assertion of self-interests. (…)
Taken together, these studies underscore the utility of incorporating cultural traits, such as individualism–collectivism, in macro- (e.g. cross-population) and micro-scale (e.g. within-population) models of GxE factors underlying complex affective disorders and the importance of culture–gene coevolutionary theory for understanding typical and atypical human behaviour, more broadly construed.”
— J. Y. Chiao and K. D. Blizinsky, Culture gene coevolution of individualism - collectivism and the serotonin transporter gene (pdf), Northwestern University, Evanston, IL, USA, The Royal Society, 28 October 2009
