Abstract
Though major depressive disorder, panic disorder and PTSD are twice as common in women as in men in several epidemiologic studies, gender difference in the prevalence of social anxiety disorder (SAD) is not so large. Why not? In the viewpoint of brain science, hypersensitivity of amygdala and dysfunction of prefrontal cortex were known to relate with both depression and anxiety. While chimpanzees are believed to be male dominant in their dominance hierarchy, bonobos are female dominant. In the history of the world, the human society was male dominant, such as patriarchy and military. Recently, Kano et al. (2015) reported that bonobos make more eye contact than chimpanzees. Eye contact is a powerful communication tool. Women may use eye contact better than men. Patients with SAD often avoid eye contact as one of their safety behaviors. In the viewpoint of killing each other on the battlefield, men tend to feel fear of other men in dominance hierarchies in the same way as women. The human nature about fear of other human beings may be a reason for no large gender difference in SAD.
