We may think of our brain as one single unit that operates our body and mind, but actually it is a little bit more complex than that. Evolutionarily, we can trace three major levels of developments that have distinct features, needs, feelings and behaviors. Understanding our brain this way can be very helpful to better understand our own complexities and behaviors. In this article I will give you a simplified but very practical way to think of the three levels of your brain and what they do.
Your three different brains
Paul McLean, an early (comparative) neuroscientist developed his Tri-une brain concept to describe how our brain’s evolutionary development can be roughly traced back to three major phases. These developmental phases resulted in three distinct levels: the reptilian level, the mammalian level and the primate level.
Although in modern neuroscience this distinction is viewed as a strong oversimplification, it nevertheless remains very helpful in categorizing our broad patterns of thinking, feeling and behaving. The three different levels of our brain are very much integrated into a whole and operate in unison, but at different times the core needs of each level can still be dominantly experienced.
We will take a short tour through the three different levels of our brain to see what exactly makes them different. This will help you understand what each level does for you and how you experience his. And importantly, what you can do to bring them back to balance when needed.
The reptilian level
The first and oldest level that developed is the reptilian brain, starting several hundreds of millions of years ago. On this level, we find core survival functions like regulating energy, coordination of movement, sensory systems and the survival behaviors like fight, flight and freeze. The core need of this level can be summarized as safety. Behaviors on this level focus on avoiding harms. Whenever we perceive risks, uncertainty and danger we are prone to function from the reptilian level of our brain.
Your reptilian brain speaks to you mostly through (unconscious) sensations in your body. Many of us don’t pay too much attention to our bodily sensations, but they contain valuable information about our current physiological state. Unconsciously our physiological state will have a strong influence on our perceptions of the world and our reactions to others around us. Practicing your bodily awareness, for example through body scan meditations, can help you tap into this source of bodily ´knowing´.
The mammalian level
This is the second level of our brain to have developed during our evolution, roughly starting 200 million years ago. In the mammalian level the most important functions are emotional feelings, motivation and (basic) bonding behaviors. This level of our brain has the capacity to learn and store emotional memories of what type of actions and situations result in rewards and which result in punishment or aversive experiences.
The core need of the mammalian level is satisfaction of our needs, through foraging and seeking or approaching rewards. This is mainly facilitated by dopamine, a neurotransmitter that facilitates motivated behavior (as opposed to more inhibitory or avoidant behavior).
The primate level
The third and most modern level of our brain is found more or less exclusively in primates. This level started to develop approximately 60 million years ago. On this level we find the development of more abstract capacities like language, meaning, thinking and planning.
The neocortex is very proficient in making associations, storing episodic (autobiographical) memories and categorizing factual information. This is an enormous improvement over the previous two levels – as it enabled humans to efficiently coordinate the complexity of group behavior like no other animal can.
Also, through the prefrontal cortex specifically, this modern level of the brain can inhibit the two lower and more primitive levels. This helps us regulate our feelings and behaviors, especially those coming from lower levels of the brain that would otherwise make us go into full fledged fight, flight or freeze every time something slightly problematic arises.
The core need on this level is connection through attaching to others. Although bonding behavior is already developed in mammalian levels, in the primate level we see the capacity for much deeper and complex social behaviors. Thanks to the most evolved part of our nervous system, we have the capacity – when in danger – to first look and call for help from others. Preferably from those that belong to our tribe, although not necessarily. This so-called ‘co-regulation’ helps us inhibit the more intense fight and flight energies when there is danger. Only if looking for help through making contact with others fails, we revert to evolutionarily older strategies like fighting, fleeing or freezing.
Three brains, three experiences
Whenever the needs of these three brains are met or unmet, we have specific experiences related to each of the three levels. In the table below you can see what positive and negative experiences are related to the three levels.
This table simultaneously shows examples of experiences we can seek out to deliver an antidote to the negative experiences. For example, if you notice that people seem threatening and you’re feeling anxious, you know that you’re probably in the reptilian (survival) mode. An antidote to such experiences may be to consciously relax yourself, for example by actively orienting your attention to the fact that you’re okay right now.
Or if you’re feeling a lot of frustration throughout the day, it is likely that your mammalian brain perceives that you are being thwarted on your path to completing an activity or reaching a goal. Here you might balance this experience by visualizing yourself reaching the goal or remembering a previous experience of mastery or achievement.
And finally, on the primate level you may experience something like exclusion or feeling neglected. Here you might create or remember an experience of being included or loved by someone, to bring in an antidote to the negative experience.
Giving your three brains what they want
Now that you have a general map for your brain’s different levels, you can check in with yourself during the day and get a better grip on what level of your brain is dominant and maybe asking for attention. Taking care of your core needs of safety, satisfaction and connection will ultimately result in feelings of peace, contentment and love.
Another powerful strategy is to train the most evolved part of your brain, specifically the prefrontal cortex – which somewhat jokingly has been called the Chief Executive Officer of your brain. The prefrontal cortex (which is part of the neocortex and primate level of your brain) can regulate your nervous system, inhibit the fear response and help you be flexible in responding to situations. According to scientific studies both meditation and exercise can significantly and measurably improve your prefrontal cortex – your CEO – functioning.
For that reason, a recommendation I want to leave you with is to look into Dr. Dan Siegel’s books for more on the science behind this and especially his guided meditation to get started in optimizing your three brains. I use these for myself on a daily basis and often recommend them to my clients.
Also Rick Hanson’s book Hardwiring Happiness is a great tip to continue reading into this subject. This article is in part based on this book and Hanson’s elaboration on Paul McLean’s Tri-une brain concept.