Sunday, June 15, 2008

Are Conservatism and Liberalism Genetically Inherited?

In 2005, the American Political Science Review published an article by John Alford, Carolyn Funk, and John Hibbing entitled "Are Political Orientations Genetically Transmitted?." Relying on studies of twins that compare the traits of monozygotic (identical) twins and dizygotic (fraternal) twins, they concluded that propensities towards "conservatism" or "liberalism" are indeed strongly influenced by genes, because genetics accounts for approximately half of the variance in ideology. This article received wide coverage in the popular press, including an article in the New York Times.

Now, in the June 2008 issue of Perspectives on Politics--published by the American Political Science Association--there is a critique of this article by Evan Charney along with responses to Charney by Alford, Funk, and Hibbing in one article and by Rebecca Hannagan and Peter Hatemi in another. The debate in these articles provides a good introduction to some of the controversies surrounding behavior genetics, particularly as applied to the social sciences.

Unfortunately, one sees here a recurrent problem in the debate over the genetics of human social behavior--both sides in the debate tend to employ "straw man" arguments. Like many critics of behavior genetics, Charney attacks this field of study for promoting genetic determinism. Like many proponents of behavior genetics, Alford, Funk, Hibbing, Hannagan, and Hatemi attack their critics as environmental determinists. But when one looks carefully, one can see that no one is defending genetic determinism, and no one is defending environmental determinism. In fact, everyone in the debate agrees that human behavior arises from a complex interaction of genes and environment. But instead of trying to work through this interactionist complexity, the participants in the debate ridicule their opponents by attributing to them positions that they don't really take.

Charney says that he is resisting the tendency "to view ever more complex attitudes or systems of belief as in some sense genetically determined (or 'heritable')" (299). He disagrees with the article by Alford, Funk, and Hibbing as claiming "that political orientations are genetically determined" (300). But this is not what Alford, Funk, and Hibbing say. Instead, they say that they have presented evidence "that political orientations are transmitted genetically as well as culturally" (321), and they emphasize that "genes and the environment interact in a complex fashion." Similarly, Hannagan and Hatemi say that "genetic factors exert their influence on an organism in a particular environment such that any trait must be a combination of the two factors," and so "it may be the case that the more we learn about genes the more we discover the importance of relevant environmental influences on behavior" (332-33). It seems then that Charney's attack on genetic determinism is an attack on a straw man.

But the same rhetoric strategy is employed by the other side. Alford, Funk, and Hibbing say that they are challenging "environmental determinism," which claims "that genes are irrelevant to human behavior" (321, 325). They also attack Charney as a "dualist" who assumes an absolute separation between mind and body. Similarly, Hannagan and Hatemi criticize Charney's "exclusively environmental explanations" as assuming a "social determinism" that is implausible (330, 333). But then Charney says that any claim "that genes are irrelevant to human behavior" is "preposterous" and is not the claim he has made (339-40). He also indicates that nowhere in his article does he endorse the "dualism" attributed to him by Alford, Funk, and Hibbing.

This straw-man argumentation rests on a false dichotomy of nature and nurture. Almost no one believes that human behavior is determined completely by genetic nature. And almost no one believes that human behavior is determined completely by social nurture. Almost everyone who examines the relevant evidence and argument would have to conclude that for complex human behavior the causes must be both genetic and cultural.

There are good reasons to agree with Alford, Funk, and Hibbing that there are some genetically inherited propensities of temperament that influence one's political ideology. But what one inherits directly is not the tendency to "conservatism" or "liberalism," but "orientations to bedrock principles of group life" that might have an evolutionary history going back to our earliest evolutionary ancestors (324-25).

For example, one distinction between liberalism and conservatism made by Alford, Funk, and Hibbing is that conservatives tend to be pessimistic about human nature, while liberals tend to be more optimistic. This conforms to what I have said in Darwinian Conservatism about the "realist" view of human nature in conservative thought as opposed to the "utopian" view in liberal thought. But, as Charney indicates, the detailed elaboration of conservative and liberal thought is a product of culturally contingent circumstances that arose over the history of Europe and the United States over the last two centuries (for instance, the divergent reactions to the French Revolution). Consequently, the political debate between conservatives and liberals will manifest a complex interaction of inherited temperament and cultural experience.


R Hannagan said...

My (Hannagan and Hatemi) comment was based on a manuscript that Charney was allowed to revise and resubmit before publication. Although the overall substance of his article did not change, he did, after reading the comments and realizing that he was being accused of being "anti-science," change his tone to that of tolerance for the notion that genes might have some influence on political behavior. Even so, I do not believe the exchange was merely an exercise in putting up straw men. The cites Charney uses and overall aim of his critique of AFH seems to suggest he finds explorations of the genetic influence on political behavior to be wrong-headed. I do not find a satisfying explanation for this in his essay. I was hoping that his final reply would have convinced me.

My (Hannagan and Hatemi) piece suggests a more appropriate critique of AFH. Rather than suggest such ideas are confounding and hard to test, or the tests really aren't testing what they attempt to test, we should do better to clarify our hypotheses based on sound theory (modern Darwinian theory of evolution by natural selection) and test those hypotheses with increasingly sophisticated methods. Why?
As the debates in our own discipline (political science) suggest, social science does not speak with a single voice and neither does "science." This does not mean that we cannot speak to each other and hold each other accountable for our claims, however. The scientific method provides us the tools to explore our questions such that others can retest, and thereby critique, our work. Outside using the scientific method, I do not find critiques of methods (as the Charney piece attempts to be of the twin methodology employed by AFH) particularly useful.


Evan Charney said...

To set the record straight: If anyone thinks that we are attributing to Fowler, or anyone else, the view that “it’s all in the genes,” then they have profoundly misunderstood our article. Fowler does not say that, nor does anyone else as far as we are aware.

Besides showing the gross errors in this study, our point is that no single polymorphism could conceivably predict, or be a risk factor for, complex behaviors such as voting behavior (or most human behavior). Consider the following:

Researchers bred aggressive fruit flies over many generations resulting in a hyper-aggressive strain. In comparing the difference between hyper-aggressive and normal fruit flies, they discovered differences in the transcription levels of over 1550 genes (the heritability of aggression was estimated at only 10%, meaning that 90% of the variation was due to environmental factors, even though the researchers thought they raised the flies in identical environments). These same proteins encoded in these genes were also involved in a host of other physiological processes, including such basic processes as cell division.

In a situation such as this, no single genetic variation could possibly predict differences in aggression in fruit flies. Yet a single polymorphism can predict voting, liberalism, etc. in humans?

Do we believe that genes “matter”? Of course genes matter. No monkey ape zygote is going to develop into a liberal voter, and no human zygote is going to grow a chrysalis age three and turn into a butterfly. This is really not what this controversy is all about. Rather, it is about whether or not a common variation on a single gene can so influence human behavior (such as voting) as to be predictive of that behavior. Clearly, it cannot.

Now, regarding data mining: The same two genes associated with voting behavior have also been associated by other researchers with a bewildering array of traits. For example, one of the genes associated with voting - the serotonin transporter gene - has also been associated with e.g., agreeableness, alcoholism, Alzheimer’s disease, anger/aggression, anorexia, attachment, attention deficit hyperactivity disorder, autism, bipolar disorder, blushing, borderline personality disorder, brain activation by colorectal distension, brain activation in processing errors, breast cancer, bulimia, chronic fatigue syndrome, cleft lip, conscientiousness, contraception use, cooperativeness, creativity, deductive reasoning, depression, epilepsy, extraversion, fearfulness, fibromyalgia, pathological gambling, gastric emptying, harm avoidance, heroin use, attitudes toward individualism and collectivism, insomnia, intelligence, interpretive bias, irritable bowel syndrome, job satisfaction, loneliness, longevity, maternal sensitivity, migraines, neurodermatitis, neuroticism, novelty seeking, number of sexual partners, obesity, obsessive compulsive disorder, openness, optimism, osteoporosis, panic disorder, parenting, Parkinson’s disease, persistence, periodontal disease, postpartum depression, posttraumatic stress disorder, premature ejaculation, premenstrual dysphoria disorder, psoriasis, resiliency to victimization, reward dependence, schizophrenia, seasonal affective disorder, shyness, sleep apnea, smoking, social phobia, sudden infant death syndrome, suicide, utilitarian moral judgments, and well-being.

This list is by no means complete, and for the other gene associated with voting (the MAOA gene), the list is as long (a partial list of associations that have been made with specific polymorphisms on four genes and a bewildering array of phenotypes, expanded from our article, is available at: