The more primitive brain systems and brain stem are internal, the cognitive and reasoning functions having developed upon this. The cortex, where inductive reasoning occurs, the highest level of reasoning and the latest development, is the outermost layer of the brain. Eventually, As intelligent life emerges, it does so by gaining the capacity to symbolize, to manipulate its environment in terms of symbols. Symbols begin as cognizance of observed relationships and progresses through concepts, language, etc. All of this symbolizing is perception, it is not the subject reality.
Existence stands alone, preceding and independent of perception.
As intelligent life emerges, there are far more concerns and questions than for which there is knowledge. In the absence of knowledge, intelligent life fills the voids with perception. This perception, in the beginning, bears little relationship to factual reality, especially in terms of the fundamental nature of things and how things work. As language and the ability to communicate perception develops, highly delusional cognitive systems come into place, further degraded by any deliberate insertion of false concepts. The primitive humanoid cannot understand the forces of nature and the unpredictability of fortune.