The reptilian brain is considered one of the three levels of human brain evolution. It corresponds to the ancestral brain that governs the regulation of vital functions (breathing, heart rate, blood pressure ...), natural needs (eating, drinking, reproduction) and primitive behaviors (fear, hate, survival instinct ...). Many vertebrates (fish, birds, amphibians, reptiles) are also governed by the reptilian brain. In humans, it is, from an anatomical point of view, in the brainstem and cerebellum. The other two parts of the brain in this category which appeared more recently are the limbic brain, which manages emotions and judgment, and the neo-cortex corresponding to the cerebral hemispheres and enabling learning, imagination, and language, specific to humans.