Cake is a marvelous thing. It comes in all varieties of shape and size, understated or ornamented, whole or tiered, vanillaed or chocolated or anything-ed in between, and it always seems to deliver. One especially satisfying feature of the mighty cake is that it presents itself to the taster as a unified whole, rather than as a mere assemblage of ingredients, baked at a specified temperature for a specified time.
Sure, the baker knows precisely what went into the baking of her cakes, and the taster may have her suspicions. But neither is likely to take a bite and alight upon the eggy bit, the floury crumb, the oveny morsel. Assuming a well-mixed, well-made cake, each slice is an ode to integration and harmony. Yet, a cake is unquestionably the product of many distinguishable elements: a physical interaction of ingredients, technique, and temperature. If it is truly marvelous, it is not truly miraculous.
So, too, is human development. Indeed, it is hard to a find a more apt metaphor for prenatal development than “a bun in the oven.” We are made by genes, but not by genes alone; we are made by nine months of incubation, by parental love, by instruction, but by none of these alone. The complexity of the effects of these elements on development is staggering, and it is no exaggeration to say that we are more than the sum of our parts. Yet, just like a cake, we are made of our parts nonetheless.
So, when I read the thoughts of several of the scholars cited in Thomas B. Edsall’s recent article about “genopolitics,” I had to wonder whether they enjoyed a nice piece of cake now and then. “Genopolitics” is the lousy name given to the (currently tiny) branch of behavioral genetics applied to political contexts. In other words, it refers to the effects of variability in DNA on political behavior.
A frequent objection to the study of behavioral genetics, raised by a few in Edsall’s post, is one of insurmountable complexity. Alan Abramowitz, for instance, suggests that “it’s very difficult to separate the influence of genes from that of the family, the community and the social environment in general.” Evan Charney, one of the chief critics of the whole enterprise, goes further:
On the surface, these arguments from complexity seem perfectly reasonable. Of course it’s difficult to separate the effects of genes from other causes and, certainly, the former are not privileged over the latter in the process of development. So, one might fairly ask, how could a mere gene affect behavior, let alone ones involving modern cultural institutions?
Let us reconsider the cake for an answer. Handed only a recipe—a list of ingredients, an oven temperature, and a technique—it would be very difficult to determine how each element (quantity, quality, or kind of eggs, sugar, and flour; changes to temperature or baking time, etc.) affected the final confection. Handed many, many recipes that varied from one to the next, however, affords the baker the opportunity to make an educated guess. Better, the baker can systematically vary each element (one at a time at first, then in pairs, and so forth) and compare cakes. Better still, the baker replicates each recipe and has many tasters taste the cakes to compare notes.
The same general logic applies to studying the effects of genes on behavior, political or otherwise. About 90 years ago, scientists discovered the “many recipes” approach to behavioral genetics. This entails variations on the “family design” theme, such as studies of behavioral similarities between identical and fraternal twins, with some pairs raised together and others raised apart. More recently, scientists have also discovered methods to measure genotype directly and use sophisticated statistical techniques to study associations between genes and behavior. Both approaches have been continually refined over the years, and provide excellent control (methodological and statistical) for the problem of separating the effects of genes from those of the environment.
But there is also the “systematic” approach that originated thousands of years ago, with the first attempts to domesticate livestock. In point of fact, we have appreciated the effects of genetic inheritance on behavior for considerably longer than we have acknowledged the existence of genes themselves. These days, we call such methods “experiments,” and they are the gold standard in scientific research.
Take for instance, a fantastic body of work on monogamy among some rodent species (see here and here). Most animals do not show monogamous behavior, but prairie voles do. The behavior is regulated in part by a chemical compound called vasopressin. Importantly, this works because prairie voles have genes that create vasopressin receptors—proteins that make use of vasopressin—in key areas of the brain, whereas their promiscuous meadow vole brethren do not. Given a dose of vasopressin to these areas, meadow voles do not become more monogamous. However, if meadow voles are delivered vasopressin receptor genes to these areas and then given a dose of vasopressin, they do become more monogamous. Perhaps more spectacularly, researchers have shown the same effect of vasopressin in an otherwise promiscuous strain of mouse engineered to have a vasopressin receptor gene. This work is an extraordinary demonstration of something we have understood—in the grand scheme if not in the fine details, at least—for quite some time: genes affect behavior, and necessarily so.
Again, a cake is the interaction of ingredients, technique, and temperature; the process is at least passingly complex. Nevertheless, does anyone doubt a different result, however subtle, were the baker to substitute salt for sugar or all-purpose for cake flour? Each cake is a unitary thing, and yet the effects of the elements that produce cakes can be conceptually distinguished. The same goes for people. There is no paradox here: individual cakes and people are the products of complex interactions among their elements (ingredients or genes, temperature or TLC); comparisons of many cakes and many people can help us to uncover the effects of these elements on their outcomes.
Let me end here by saying that I've gotten myself really hungry.
Cover image by Roxanna Salceda.