Like Father, Like Son: Conflict, Negotiation and Shared Fate
Cormac McCarthy and his colleagues at the Santa Fe Institute often use metaphors to explain complex scientific phenomena because researchers from different disciplines may lack a common vocabulary. Genetic imprinting is a phenomenon that is not easy to grasp but can be explained using examples from our experiences or stories. The vivid experiences of the father and son in The Road can help us explain this science.
In The Road, the father and son must negotiate many decisions. When will they stop for the night? Should they open that door? Eat something questionable? Offer help to another traveler? They are two individuals with separate wills, but their paths and their fates are inseparable. In this wasteland, father and son going their separate ways—each trusting his own judgment—is simply not an option. Every conflict must be resolved into a joint action, one way or another.
Geneticists have discovered that the genes in our bodies are in a similar situation. Of course, the individual organism is the one who takes this or that action, survives or does not, reproduces or does not. Like the father and son, the fates of the genes in each individual are inextricably linked. However, natural selection can favor genes that take on different strategies depending on where the gene came from. These strategies can come into conflict with each other, even for sets of genes that are present within the same individual.
For about 1 percent of our genes, the gene copy that we inherit from our mothers behaves differently from the copy we inherit from our fathers. These genes, known as imprinted genes, have evolved in cases where a gene's optimal behavior differs depending on its parent of origin. Many of these imprinted genes influence our early growth and development, when a paternally derived gene favors more aggressive growth (resulting in a greater drain on maternal resources) than does a maternally derived gene. Because we have one maternally derived and one paternally derived copy of each gene, this leads to an evolutionary conflict between the genes within our own bodies.
In addition to early growth effects, many imprinted genes are expressed in the brain and influence certain aspects of cognition and behavior. We have all felt conflicted over tough decisions. Sometimes we feel as if we were literally of two minds. And of course, we are all familiar with the convention of the little angel and the little devil sitting on our shoulders, whispering in our ears, urging us to do different things. The discovery of these imprinted genes suggests that this feeling may, in fact, have a basis in the genetic conflicts being played out in our brains.
When our genes disagree, it is difficult to predict how the conflict will be resolved. The genes may effectively reach some compromise, or one set of genes may prevail over the other. In some cases, the dynamics of the conflict produce dramatic changes, where each set of genes is worse off than they would have been if they had simply abandoned the conflict; sometimes, the compromise solution is worse than losing the conflict outright.
About the Author
Jon Wilkins is an evolutionary biologist working on genetic imprinting, or understanding how genetic traits evolve or die across and within generations. Jon grew up in Los Alamos, New Mexico, and received his PhD from Harvard University. Before joining the Santa Fe Institute in 2004, Jon started his academic career at Harvard as one of only a handful of members of the Harvard Society of Fellows.
Man vs. nature in The Road