How Nurture Affects Nature
November 15, 2017
Policymakers often debate the merits of programs to change decision-making and behavior, wondering if they have enough bang for the buck. Now there is research showing that the choices people make affect us all the way down to the genetic level, and can even influence the biology of our offspring. Epigenetics is a relatively new field that is illuminating how genes and environment interact. It has changed the nature-versus-nurture debate, replacing it with the understanding that environments and experiences can influence whether certain genes are activated or not, and even more astonishingly, showing that genetic modifications can be passed on to future generations. This research has profound implications not just for science, but for public opinion and policy, writes Tania Roth in a recent article for Policy Insights from the Behavioral and Brain Sciences.
Scientists have discovered several ways that environment shapes the activation of genes. Roth focuses on a process called methylation. Using what she calls “the 10,000 foot overview” of the process, she explains that the DNA in our cells is wrapped around proteins, like thread on a spool. The shape of that structure, which can be tightly wound or more relaxed, has a big influence: when it is relaxed, it allows genetic machinery to access the DNA and activate genetic processes. Methylation is a process that attaches a kind of “chemical tag” that affects whether the structure is compact or relaxed. Studies by Roth and others show that experiences and environments shape whether methylation occurs, which then affects whether genes are switched on or off. Ultimately, that processes influences memory, learning, mental health, and many other areas of functioning.
Methylation and other epigenetic processes help explain why early adversity impairs children’s executive functioning and learning skills. Abuse, neglect, poverty, and other negative environmental conditions change the very structure of the brain and whether genetic instructions are followed. Much of Roth’s work on early caregiving environments has used rodents, because it is simpler to isolate the effects of environmental factors when you can control them; humans’ lives have a lot of confounding factors that can be difficult to separate. But both animal and human research have shown that trauma and adverse experiences in childhood, and even in the womb, impact methylation and other genetic processes. Stress is a big factor even in adults. One study of military personnel with post-traumatic stress disorder showed that there are differences in methylation before and after deployment.
But the news isn’t all bad. Improving the environment can also improve methylation, as shown by improvement when deprived rats were given more stimulation and toys. In humans, medication and psychotherapy have been shown to change epigenetic effects and improve psychiatric symptoms, even in adults, who are past the most sensitive periods of brain development. And scientists are developing what Roth calls “a new suite of tools [that] have given us the remarkable ability to control the epigenome with extreme precision,” by using DNA sequences that seek and target specific genes or combinations of genes to control the methylation process.
Roth suggests that current findings are just the tip of the iceberg and calls for more research on epigenetic processes across multiple areas of health. She hopes this will help shape the public’s understanding and commitment to funding future research on how environments can improve – or impair – our biology and our lives. She calls on researchers to spread the word beyond academic circles, noting that, after all, “communication is how science thrives.”
Drawn from “Epigenetic Advances in Behavioral and Brain Sciences Have Relevance for Public Policy” by Tania L. Roth in Policy Insights from the Behavioral and Brain Sciences.