I’m standing frozen in terror at the entrance of an amusement park, holding the hand of an excited child, and thinking, “No. No, No. I can’t go in here.” My kid unhooks her hand, wipes the sweat on her skirt, and says sweetly, “It will be OK, Mommy. You can pick the first ride because you’re so scared,” Alert as a rabbit in a hunter’s field, I scan a few rides and choose one designed to delight a 5-year-old. It’s called Starship America, a ring of tiny rockets built for two. It goes around and around and then each rocket goes up and down. Piece of cake, I think. But as we climb aboard one of those rockets-of-death, my anxiety rises up like bubbling magma and takes over my body. My heart races, my breathing grows shallow, and I want to jump out of that steel air-coffin and run run run away. I am ashamed of my fear until I think about the work of Randolph Nesse, a psychiatrist at the University of Michigan. Nesse is a Darwinian psychiatrist interested in applying evolutionary theory to traditional views of mental illness. Instead of calling mood disorders such as anxiety or depression “illnesses,” he believes there might be good evolutionary reasons for feeling blue or scared; these feelings are not necessarily diseases or disorders, but adaptations. For example, successful, competent people with seemingly great lives present at Nesse’s clinic feeling depressed, but not knowing why. Nesse asks the usual psychiatric questions, but he also asks broader questions about their lives. Was there a goal not achieved? What’s going on with the path of their lives? Embedded in those questions can be major issues that explain why someone has lost hope, despite the trappings of a “perfect life.” Retreating into depression in the face of perceived failure makes evolutionary sense, Nesse points out, and his job is to help patients find hope again. Fear in a space ship also has evolutionary roots. Anxiety is an extended version of the fight–or-flight response which evolved to keep us alive; an animal without fear is a dead animal. But humans have a penchant for dragging the fight-or-flight response into every situation and holding onto it until we are sick. What helps, Nesse claims, is realizing anxiety is not necessarily a bad thing but a good thing, because anxiety attacks often keeps us from certain unpleasant situations. I could imagine Nesse sitting in the next rocket, talking to me above the happy screams of those around me. “Look,” he might say, “You’re whizzing around in the air in a capsule and humans didn’t evolve to be in this situation. It is indeed scary. You have your child in that rocket and you are appropriately terrified she will fall out. It makes sense, and it will be over soon.” I try to hold on to those thoughts as our rocket lands and my kid says, “Wasn’t that fun? How about a roller coaster?” Meredith F. Small is an anthropologist at Cornell University. She is also the author of "Our Babies, Ourselves; How Biology and Culture Shape the Way We Parent" (link) and "The Culture of Our Discontent; Beyond the Medical Model of Mental Illness" (link).