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

© by madaise

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

© by mikebaird

This is the type of brain developed by most mammals on top of their reptilian brain. It is your emotional brain – this is the brain that is responsible for making you feel the way that you do. This brain creates chemical messages that allow you to store information in memory. The more emotionally charged the message is, the stronger effect on the brain it is going to have.

This part of the brain is able to learn from past experiences. It ensures that you feel pleasure from the activities intended for your survival, such as eating and sex. This function helps to ensure that you will continue to repeat the favorable behaviors. The emotional brain is also able to learn to associate pain with activities that may threaten your existence, such as getting burned or getting hit by a car.

We like to think that we make most of our decisions based on what we think is right. In actuality, however, we make most of our decisions, on what we feel is right. And this “feeling” is the response that we get from our emotional brain.

The Primate Brain

primate © by chadh

This is the thinking brain. It controls such things as thinking, language, and creative thinking. This brain is responsible for telling us who we think we are.

Unfortunately, this brain does not have a priority over its two predecessors. For example, in an emergency situation, your brain can cause you to automatically react in a certain way, without you ever having to think about it. This function is crucial to our survival, but it can also present some real problems if our subconscious mind decides to take over, as it often does, in non-emergency situations.

In the next chapter, we are going to take a closer look at some of the possible triggers (external events) that can cause our reptilian and emotional brains to take over.