pgEd recently unveiled a new lesson plan, “Genes, Environment and Genetic Complexity: Genetics and Aggression.” Like all of our materials, it is aligned with the Common Core and freely available on our Lesson Plans page.
This lesson was developed in response to questions we were seeing in the classroom, and it took a new urgency with each terrible incident of mass violence in the United States and abroad. The search for answers to explain aggressive behavior often includes biology. The literature (and range of opinions) is enormous in this area, but we have highlighted a few articles and clips that illustrate both the biological as well as the social and cultural complexity of this topic.
“Seeking Answers in Genome of Gunman” (New York Times, December, 2012)
“The Science of Success” (Atlantic Monthly, December, 2009)
“Could Genetics Help Us Understand Mass Killers?” (Hartford Courant, 2012)
“Brain Injury rate 7 times greater among U.S. prisoners” (Scientific American, 2012)
Video clip of Nova’s “Can Science Stop Crime?”
With the reading, the core of the lesson plan is the “Key Concepts” study guide for students. It is shared below. The Lesson Plan has more details, links and background. This lesson is of course meant for classroom use, although the content – the background, the links and articles, and the video clip – could be of interest to anyone seeking an understanding of how genes and environment interact in the context of complex behaviors such as aggression.
Aggression: “Most social psychologists define human aggression as any behavior intended to harm another person who does not want to be harmed” (Baron & Richardson, 1994; Bushman & Huesmann, 2010). It is important to understand aggression not as a feeling or an emotion, but as an action. Another key concept is that a person taking aggressive action is doing so intentionally, with the goal of harming a victim.
This description is adapted from: http://www.psychology.iastate.edu/faculty/caa/abstracts/2010-2014/12DAB.pdf
Genetic complexity: Many of our traits are influenced by more than one gene. Even height, which is often assumed to be a relatively simple trait and runs in families, is controlled by the action of at least 180 regions in one’s genome. In addition to this complexity, the environment also has an impact. Diet, exercise, and maternal and childhood health all play a role. Coming back to the example of aggression in this lesson, it is important to think about the complexity of human behavior, which is impacted by an intricate network of genes in combination with the environment and social experiences. Many of these concepts are covered in Scientific American’s 2010 article, “Complex Genetic Trait Research Reaches New Heights”.
Biological determinism: This is a framework for understanding humans through a biological lens and aims to explain complex human traits as being largely, if not entirely, dictated by biology, particularly our genes. This theory downgrades, if not dismisses, the role that culture and environment might have in shaping human behaviors. Many scientists have moved past this theory and are focusing also on interactions between genes and environment and how that relationship may impact traits and behaviors.
Population genetics: Your DNA sequence can inform you about your predisposition for certain traits, such your likelihood for reaching a certain height or developing a disease. It is important to note, however, that predispositions are not guarantees. For example, people who carry certain mutations, also called variants, in the BRCA1 or BRCA2 genes have a higher likelihood of developing breast and/or ovarian cancer. Knowing this information can be beneficial for making healthcare decisions or planning for the future. However, some people who carry particular mutations in BRCA1 or BRCA2 will not develop the disease. Conversely, as there are mutations in genes other than BRCA1 and BRCA2 that can lead to breast cancer, a person who is free of these mutations still has the possibility of developing breast cancer.
The same principle can be applied to the genetic underpinnings of aggression. In fact, to date, there is no genetic variant that has been perfectly correlated with aggressive behavior and, for those variants that some researchers have correlated with aggressive behavior, there is much controversy. Finally, we point out that correlations are statistical descriptions of populations consisting of many people and, therefore, cannot be used to determine whether or not a given individual will exhibit aggressive behavior.