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Make Connections The limbic system is a set of brain structures located on top of the brainstem and buried under the brain’s gray matter. Limbic system structures are involved in many of our emotions, including fear, anger, and pleasure. Other structures within the limbic system have to do with memory and our sense of smell.

What I s Surpr i se?

us happy, for example, our brains says, “Notice this! Try to get more of this in your life!” Or when something scares us, the reac- tion in our brains tells us, “Be careful!” Scientists believe that we have evolution to thank for the emo- tions we feel today. Long, long ago, the human beings who had these reactions inside their brains were able to avoid danger better. As a result, they lived longer than their companions who lacked these reactions. Because they lived longer, they were able to have children—and they passed along this trait to their chil- dren, who in turn passed it along to their children. Emotions helped early humans respond to the world around them. They were survival mechanisms that helped the human race survive. Today, emotions continue to play important roles in hu- man life. WHAT MAKES SURPRISE DIFFERENT FROM OTHER EMOTIONS? We often put emotions into categories —positive (good) emotions and negative (bad) emotions. We think of happiness, amusement, and love as positive emotions, and we usually consider sadness, fear, and hate to be negative feelings. All of these emotions, both