The limbic system is a part of the brain that controls our emotions and behaviors. It helps us feel pleasure, fear, anger, and other strong feelings. It also helps us remember things and make decisions based on our emotions. Full definition
The amygdala is part of limbic system in the temporal lobe. (edutopia.org)
Or in limbic system terms, it might not seem as unpleasant. (inc.com)
Our brain structures are based upon how our species evolved from primitive worms living in the oceans, with limbic systems becoming mutated simply because such things survived to further evolve in random ways mostly affected by our environment and basically random chance. (religion.blogs.cnn.com)