Paul MacLean theorized that the brain has three distinct parts: neocortex, limbic system, and reptilian complex. The neocortex (rational brain) is responsible for intellectual tasks such as language, planning, abstraction, and perception. The limbic system (intermediate brain) is responsible for the motivation and emotion involved in feeding, reproductive behavior, and parental behavior. The reptilian complex (primitive brain) controls the self-preservation and aggressive behavior of humans similar to the survival instincts of animals