These chaps claim to have found a "robust" correlation between the type of HTTLPR-5 allele present in a population and the incidence of individualism vs. collectivism in that population.
The HTTLPR-5 allele comes in two varieties: short and long. The short allelle tends to have a higher frequency in more collectivist nations and is represented by as much as 80% in East Asian cultures. By contrast, Europe tends to vary between 40-45%.
How does it work? Short-HTTLPR-5 alters the expression of a gene called SLC6A4 to produce less of a protein that's required for regulating serotonin, resulting in a higher concentration of serotonin in the synaptic cleft. This in turn is associated with increased risk of depression, heightened anxiety, fear conditioning, attentional bias to negative information and so on.
The article hypothesizes that collectivism and interdependence were selected in those societies in an attempt to reduce the total amount of life stressors in the environment (due to the easy predominance of life stressors). Incidentally, the level of anxiety and mood disorders in these collectivist societies is the lowest in the world, whereas the USA and Europe, being more individualistic, seem to have the highest.
a) Hofstede's study of cultural dimensions (red is more collectivist, yellow is more individualistic). This is a different cultural study on the same issue.
-Study (click on the countries to the left for information about them)
b) Frequency of Short HTTLPR-5 alleles (red is higher frequency, yellow is lower frequency).
c) and d) incidence of anxiety and mood disorders, respectively (red is higher frequency, yellow is lower frequency).
Honestly, other than the genetics bit, this is something people shouldn't find surprising, least of whom Robert Heinlein, and is almost implicit in a lot of discussion on political theory, so the conclusion isn't gound-breaking or anything. Still, it's pretty cool and the rest of the article is interesting.
Unfortunately, they decided to use the nation as the unit of analysis instead of breaking it down into cultural subregions.