The triune brain model was proposed by Dr. Paul MacLean in the 1950s. It states that humans don't just have one brain, but rather a layer of 3 brains that have each evolved on top of the other over the course of years: reptilian brain, mammalian brain, and primate brain. The Reptilian Brain This brain is the first to be developed. It is responsible for autonomic bodily functions such as heartbeat, breathing, and temperature control. It is also responsible for the most important human needs, such as survival, feeding and mating. This brain is part of your subconscious mind. It has a set of pre-programmed instructions that it will always execute. This brain cannot change or learn from past experiences. It only understands images, and does not understand language. Some of the traits associated with the reptilian brain are: aggression, dominance, obsessiveness, compulsiveness, fear, worship, submission, greed, sex, and seeking a mate. The Mammalian Brain This is