Judging what you like or dislike allows you to enjoy life. In addition, knowing what you should fear, and quickly recognizing the biological changes in your body that indicate fear, could save your life. This critical task is largely handled by a small almond-shaped structure, the amygdala, which lies deep within the bottom of the brain, not far from your ears. The amygdala receives information from many brain regions, your internal organs, and external sensory systems, such as your eyes and ears. The amygdala integrates this information with various internal drives, such as whether you are hungry or thirsty or in pain; it then assigns a level of emotional significance to whatever is going on. For example, when the amygdala becomes aware that you are alone and hearing unfamiliar sounds in the dark, it initiates a fear response, such as panic or anxiety. It then activates the appropriate body systems, the release of hormones, and specific behaviors to respond to the (real or imagined) threat. The amygdala also is activated by sensory stimuli that seem ambiguous or unfamiliar to us, such as unfamiliar sounds or people. In response to ambiguous or unfamiliar stimuli, we become vigilant and pay closer attention to what is happening in our immediate environment. If you were a dog, your ears would perk up. Your amygdala gathers as much sensory information as possible, compares it to what you already know, and then instructs other brain regions to respond.
Almost without fail, and regardless of the nature of the information gathered by your vigilant brain, the amygdala usually comes to the same conclusion: be afraid. If a sensory event, such as a sight or sound or taste, is unfamiliar; your limbic system almost always assumes that the situation is potentially dangerous and should be treated as such. If everything
is assumed to be dangerous until proven otherwise, you are much more likely to survive the experience and pass on your be-fearful-first genes. Thus, humans fear everything that is unfamiliar or not-like-me: we fear unfamiliar dogs, people who look or dress...