A study at University College London in the UK has found that conservatives' brains have larger amygdalas than the brains of liberals. Amygdalas are responsible for fear and other "primitive" emotions. At the same time, conservatives' brains were also found to have a smaller anterior cingulate—the part of the brain responsible for courage and optimism. If the study is confirmed, it could give us the first medical explanation for why conservatives tend to be more receptive to threats of terrorism, for example, than liberals. And it may help to explain why conservatives like to plan based on the worst-case scenario, while liberals tend towards rosier outlooks.