11-The zoo in your head

The human brain is compartmentalized into three general groupings: the primate, mammal, and reptile. The primate is what we think of when we think of the brain. It’s the spongy stuff on top. The reptile, or R-complex, caps the central nervous system (the spinal cord). Everything in-between is mammalian.

The primate brain performs complex calculations such as dexterous motions, subtle distinctions of light and sound patters, symbolic language, in-depth planning, imagination, logical reductions of nested causes with multiple effects of varying potentials, temporal conjecture, and any number of exercises in reasoning that basically tells us to what to avoid in the pursuit of what we want. It’s the ultimate semaphore. When all the other brains tell you to go, this is the last chance of stopping before you hurdle the wall of sanity. Although this brain has access to the whole, it is often the first we ignore.

The mammalian brain is responsible for likes and dislikes. It concerns itself with intense emotions, social status, and egotistical aims. Far too many of us spend far too much time secluded in the world of mammalian sensation. Yesteryear is trimmed with a silver lining and gilded in gold; on the other hand, bloodcurdling hate has no better home. Sound-bites construct the strings of cause and effect. Jealousy, intimacy, fun, affection, disgust, fraternity, jingoism, primitive justice, admiration, status, blind hope, and community are all examples of mammalian feelings. Minimal thought stirs deep emotion; great attachment is key. Mammals make great friends and passionate enemies.

The mammalian perception of one’s place in society influences one’s physical health both short term (how do you feel about the frown your boss just gave you) as well as long term (how do all those frowns on all those days influenced the hormonal cocktail that pours from your mammalian brain, aging you just that much more each time you experience the disappointment). It is the complex of neurons responsible for complex emotion and specific memory. All mammals, including dogs, cats, and even rats have the same feelings as us except without a large primate structure to ponder over them in the language of thought and ameliorate them with the wisdom of planning.

The reptilian brain is the base. It’s the on switch. It keeps us digesting, breathing, and our heart beating. It keeps us safe. It is responsible for our reactions to fear, hate, and lust. It loves mindless ritual and endless calm. It is one big analog switch of arousal. It governs our two autonomic nervous systems: parasympathetic and sympathetic. They work in tandem. If one is on, the other is off. One regulates digestion; the other, stimulation. One is meant to be turned on most of the time; the other, only when the time comes. The parasympathetic system promotes homeostasis or the state of healthy repair; the sympathetic puts that process on hold in order to act now. Together, they handle the six Fs: friendship, fostering, food, fight, flight, and fornication. The reptile sees peace as a fortress. The distinction of friend from foe or food fills every encounter.

There are actually two more brains but they are not in your head. Massive bundles of neurons create a mosaic of intelligence throughout your heart and digestive tract. Heartache and gut-feelings are not just metaphors but the roots, supporting this tree of life. They can override the whole with a single beat of the heart or turn of the stomach as illness teaches us all. When they are not overshadowing our minds with absolute attention, they mostly work in silence with the reptile to keep us vertical when awake and dreaming when horizontal.