Genetic variants linked to risk‑taking and violence in behavioral studies

There are many situations where taking a risk pays off, whether we think of stealth military operations, chancy shots in the final seconds of a basketball game, or significant investments in an up and coming stock option. Playing it safe pays off. But those who stick their necks out and take a chance, may bring home significant gains. It is because of these competing strategies and potential payoffs that evolutionary biologists have imagined that selection could maintain both personality types within a population — a point noted earlier for the MAOA and glucose-related genes. If selection has worked in this way, then there must be genetic variation that allows for both strategies. To date, the strongest evidence comes from a family of genes associated with the regulation of dopamine, with the memorable acronyms of DAT1, DRD2 and DRD4; each of these genes is associated with different forms, each form associated with different levels of dopamine. Recall from chapter 2 that dopamine plays an essential role in our experience of reward, including how motivated we are to get it and what we anticipate based on our understanding of the situation — have we been rewarded in the past, how often, and how much? The idea here is that those who carry genes that output a higher level of dopamine may weight rewards more heavily and thus, show risk-blindness; for these individuals, the eye is on the prize, not the path or obstacles to this prize. Across a number of studies, results show that variation in the expression of these genes is associated with high-risk, low self-control behaviors, including pathological gambling, substance abuse, sensation seeking, and financial investments. For example, in two separate studies, individuals with different variants of the DRD4 gene played a financial investment game involving real money. In one, designed by Joan Chiao, subjects decided to invest in either a risky asset with variable returns or a riskless asset with consistent returns. In the second study, the Swedish economist Ana Dreber and the American anthropologist Corin Apicella allowed subjects to either walk away with an initial starting pot of money, or to invest some of it ina risky asset. Those with the DRD4 variant that expresses higher levels of dopamine were more likely to pursue the risky investment. What this work reveals is that part of the variation we observe among people who make risky investments, drink too much alcohol, and gamble with their income, is due to variation in the dopamine family of genes. These are hidden risks that come to life thanks to molecular biologist’s microscope. What also comes to life is the fact that these same genes are relevant to violence, causing some to strike out even though there are significant risks and terrible consequences. In several studies, using an American health data base of several thousand adolescents, results consistently show a relationship between particular variants of the dopamine genes and violence. For example, the sociologist Guang Guo examined the relationship between violent delinquency — involving use of guns and knives — and variation in DRD2 and DAT1 among 2,5000 individuals ages 12-23 years. DRD2 was of particular interest because medical records and clinical trials reveal that administering Hauser Chapter 4. Wicked in waiting 135 HOUSE_OVERSIGHT_012881