FuturePundit points me to a new paper in Science, Political Attitudes Vary with Physiological Traits:
Although political views have been thought to arise largely from individuals’ experiences, recent research suggests that they may have a biological basis. We present evidence that variations in political attitudes correlate with physiological traits. In a group of 46 adult participants with strong political beliefs, individuals with measurably lower physical sensitivities to sudden noises and threatening visual images were more likely to support foreign aid, liberal immigration policies, pacifism, and gun control, whereas individuals displaying measurably higher physiological reactions to those same stimuli were more likely to favor defense spending, capital punishment, patriotism, and the Iraq War. Thus, the degree to which individuals are physiologically responsive to threat appears to indicate the degree to which they advocate policies that protect the existing social structure from both external (outgroup) and internal (norm-violator) threats.
ScienceNow has a write up for the rest of us. Brandom Keim has posted figures 1 2 and 3 from the paper. The physiological correlates to differences in such complex phenotypes are very interesting, because a large number of behavior genetic studies show significant heritabilities for many of these traits. By heritability, I mean that you can predict an X proportion of the variation on trait Y from the variation of genes. Does this mean that there was selection for conservatism and liberalism in the past? Does this mean that there are genes for conservatism and liberalism? NO!!! That’s just plain retarded.
Most behavioral traits have many upstream variables, some of which interact with each other. In the older way of thinking a behavioral trait was purely a function of various exogenous inputs; that is, one was a blank slate whose outlook was shaped by environment. A more nuanced view strongly suggests that many behavioral traits are modulated by various predispositions which one is born with. On the level of a population we can make some general assertions about the nature of the relation of various independent variables to the dependent variable. That doesn’t mean that we are saying something as naive as genotype 1 always results in phenotype 1. As an illustration, consider male homosexuality. It seems there’s a strong biological predisposition for this trait. Most males prefer vaginal intercourse with a female over anal intercourse with a male, to the point where they may never experience the latter. But, a subset of males who are imprisoned do engage in intercourse with other males, despite the likelihood that these individuals are only marginally more likely to have any innate biologically biased preference for this behavior. Yet changing the exogenous environmental variables (i.e., simply removing the possibility of sex with women) can result in a shift in the behavior. This does not mean that homosexuality is predominatly environmental, that would be a retarded inference (unless of course 80% of men were imprisoned, in which case most of the variation in the population of sexual behavior might be controlled by an environmental parameter).
The more complicated model above is a possible illustration of what might be going on. I decided to use the Big Five personality traits since I know that Openness is correlated with being politically liberal. That doesn’t mean I think that these are the only mediating variables of note. Rather, I just wanted to illustrate in a concrete manner what the heritabilities might mean, and how they’re playing out. I also want to emphasize that terms like “liberal” and “conservative” should be thought of like “tall” or “short,” not 6 feet 2 inches vs. 5 feet 3 inches. In other words, they are relative traits which can only be understood by the whole distribution of the population.
For example, consider if the “conservative” psychology is typified by a heuristic & bias which orients toward conformity to current norms. In contrast, the “liberal” psychology has a more relaxed heuristic and is less biased toward current norms. That means naturally that liberal personality types would “random walk” out of the the central tendency of the population more often, so that you would see average differences between the two groups. But, that doesn’t define the distribution itself. What is conservative in 2008 might very well be rather liberal in 1950. For example, arguing against gay marriage but accepting the possibility of civil unions.
So it’s complicated. But it’s comprehensible. Does this matter for you? The physiological responses above are interesting, because it seems like you might be able to test at a very young age for them. If you are an adoptive parent perhaps you might want to screen your potential children for political compatibility. A few weeks ago I listened to a documentary about a woman in Argentina who had been kidnapped as an infant and adopted by a different family. In her particular circumstances here biological parents were left-wing activists killed by a military junta. Her adoptive family were associated with the right-wing junta. She did not find out about her origins until she was 18, but, she observed that she had always had political differences with the family in which she was raised and was active in left-wing politics as a teenager. Remember she was adopted as an infant! This does not mean that I believe that the causal sequence here is predominantly genetic; I’m simply saying that examples such as this illustrate the possibility, and twin and adoption studies strongly suggest that political orientation has a large heritable component. In any case, even if you have a child whose predispositions are different from those of the family into which they are adopted or born (you never know how the alleles will resegregate!), if you know the biological bias ahead of time that might facilitate appropriate “reeducation.” After all, environment does matter and might make a difference if one is willing to put the effort into it. Though I would add that I’m personally skeptical that if self-actualization and happiness are what anyone wants for their children that such reeducation toward parental norms will foster those ends. But I guess whether personal happiness is more important than some absolute standard of right and wrong is a normative question at the end of the day itself, and my mooting of the choice shows my liberal hand.*
P.S. I hope readers immediately note that an obvious inference from what I say above is that conservatives, all things being equal, should be able to engage more easily in concerted collective action on a broader scale than liberals. Within group conformity is generally a positive trait when it comes to individuals coalescing together to operate in a quasi-organismic manner. The perception that liberals tend to fracture into squabbling interest groups with different priorities about what should be the first and primary course of action might be less surprising. “Us vs. them” has more power when you fear the them….
Related: Heritability of voting. Genetic vs. heritable trait.
Addendum: One of FuturePundit‘s commenters alludes to epigenetics….
* Yes, I’m personally generally libertarian, but many of these psychological classifications tend to cluster libertarians with liberals. This is what Virginia Postrel might term a “dynamist” thing. Because of these peculiar contingencies the r-squared of political classifications of Left-Right on psychological classifications of Left-Right might be less than 1.