Genes and Values: The Dopamine Connection

01/31/2014 02:37 pm ET | Updated Apr 02, 2014

Stereotypes are, way too often, unfair and cruel caricatures.

That said, some stereotypes contain a kernel of truth, which is why they are an important cognitive tool for classifying a complex world. Consider the widely held view that Asians are much more connected to others, more interdependent, while European Americans are self-reliant individualists. This overarching cultural difference, in a very basic form of social orientation, has been validated by two decades of research. It is manifested in traits ranging from self-expression to self-esteem to views of happiness.

But all cultural generalizations are wrong when it comes to individuals. We all know Europeans and Americans who are self-effacing and communitarian in their world view, and Asians who are fiercely independent. So why do some individuals conform to cultural norms and others not?

One possibility is genetics. There are no genes for individualism or for social connection -- world views are far too complicated for that -- but perhaps there is another way that genes are interacting with the world, with culture, to produce individual variation in this perspective. That's the idea that University of Michigan psychological scientist Shinobu Kitayama and his colleagues have been exploring recently. They had the idea that genes might make people more or less susceptible to cultural norms. More specifically, they theorize that a particular gene, the so-called DRD4 gene, might contribute to the learning of individualistic or communal values.

Why this specific gene? Well, to vastly oversimplify, it's known that variations in this gene influence the efficiency of a brain chemical called dopamine, and that dopamine transmission in turn stimulates certain reward-processing regions of the brain. This sensitivity to rewards affects learning -- including, theoretically, the learning of cultural norms. That's the idea that Kitayama and the others tested in the laboratory.

They recruited a large group of college students, about half of European American descent and the other half Asian-born. These volunteers all completed a thorough assessment of their social orientation: Do you like being unique? Can you usually handle whatever comes your way? Are you satisfied with yourself? Is freedom of speech an important right in your mind? Those kinds of questions, all of which contributed to a score for independent mindedness -- or its opposite.

The scientists took saliva samples for DNA analysis. Specifically, they sorted the volunteers into those with more dopamine signaling and those with less, based on variation in their DRD4 gene. They crunched together the data on genetics and on social orientation, and here's what they found:

The European American volunteers were significantly more independent-minded, and Asians much more interdependent. That part was no surprise. But here's the novel and intriguing result: This important cultural difference was much more pronounced for both Asians and European Americans who carried the stimulating version of the dopamine gene. Indeed, there was absolutely no difference between the European Americans and Asians who did not carry this gene variation. It appears they lacked the genetic variant that rewards cultural learning, including the acquisition of these characteristic views of the world.

This study, which will be published in the journal Psychological Science, is the first to show that the DRD4 gene plays an important role in modulating cultural influences. But the study raises a lot of questions, too, including this one: Previous work has linked the same gene variation with behaviors that violate social norms, including financial risk taking and heavy drinking. Why would the same gene promote both desirable and undesirable behavior? One possibility, the scientists offer, is that cultural norms are acquired under favorable conditions, including good parenting, and the deviant behaviors under more adverse circumstances.

The findings also raise questions about the co-evolution of genes and culture. It's possible, Kitayama argues, that this genetic variant became more prevalent as cultural groups emigrated, deep in our evolutionary past. Perhaps the increased sensitivity to rewards motivated groups to move, or boosted cooperation within a culture, or had some other effect that in turn boosted the group's chances of survival under harsh, primitive conditions of the frontier.