A reflection on our reptilian brains.

Now of all the things I am not, I am neither a biologist nor a scientist of any description.  However, general knowledge told me years ago that the human brain is composed of three areas, as the following diagram shows.

A quick web search brings up THE EVOLUTIONARY LAYERS OF THE HUMAN BRAIN, from which I quote:

The first time you observe the anatomy of the human brain, its many folds and overlapping structures can seem very confusing, and you may wonder what they all mean. But just like the anatomy of any other organ or organism, the anatomy of the brain becomes much clearer and more meaningful when you examine it in light of the evolutionary processes that created it.

The most efficient model for understanding the brain in terms of its evolutionary history is the famous triune brain theory developed by Paul MacLean. According to this theory, the following three distinct brains emerged successively in the course of evolution and now co-inhabit the human skull:

The reptilian brain, the oldest of the three, controls the body’s vital functions such as heart rate, breathing, body temperature and balance. Our reptilian brain includes the main structures found in a reptile’s brain: the brainstem and the cerebellum. The reptilian brain is reliable but tends to be somewhat rigid and compulsive.

The limbic brain emerged in the first mammals. It can record memories of behaviours that produced agreeable and disagreeable experiences, so it is responsible for what are called emotions in human beings. The main structures of the limbic brain are the hippocampus, the amygdala, and the hypothalamus. The limbic brain is the seat of the value judgments that we make, often unconsciously, that exert such a strong influence on our behaviour.

The neocortex first assumed importance in primates and culminated in the human brain with its two large cerebral hemispheres that play such a dominant role. These hemispheres have been responsible for the development of human language, abstract thought, imagination, and consciousness. The neocortex is flexible and has almost infinite learning abilities. The neocortex is also what has enabled human cultures to develop.

These three parts of the brain do not operate independently of one another. They have established numerous interconnections through which they influence one another. The neural pathways from the limbic system to the cortex, for example, are especially well developed.

I’m well into reading the book Waking The Tiger: Healing Trauma authored by Peter A. Levine.  As early as Chapter One, Peter Levine explains [my emphasis]:

The involuntary and instinctual portions of the human brain and nervous system are virtually identical to those of mammals and even reptiles. Our brain, often called the ‘triune brain,’ consists of three integral systems. The three parts are commonly known as the ‘reptilian brain’ (instinctual), the ‘mammalian or limbic brain (emotional), and the ‘human brain or neo-cortex’ (rational). Since the parts of the brain that are activated by a perceived life threatening situation are the parts we share with animals, much can be learned by studying how certain animals, like the impala, avoid traumatization. To take this one step further, I believe that the key to healing traumatic symptoms in humans lies in our being able to mirror the fluid adaptation of wild animals as they ‘shake out’ and pass through the immobility response and become fully mobile and functional.

Unlike wild animals, when threatened, we humans have never found it easy to resolve the dilemma of whether to fight or flee. This dilemma stems, at least in part, from the fact that our species has played the role of both predator and prey. Prehistoric peoples, though many were hunters, spent long hours each day huddled together in cold caves with the certain knowledge that they could be snatched up at any moment and torn to shreds.

Anyway, to get back to what triggered today’s post.

If you read yesterday’s post you will recall me chatting with Jon Lavin and Jon reminding me that humans are drawn to positive messages.  But in stark contrast, the news media industry excels in promoting ‘doom and gloom’.  Why is this?  Why are we so fascinated by danger?

Well here’s my theory.

That is our evolution would not have succeeded if early man didn’t become pretty smart at identifying animal behaviours and plants and fruits that had the capacity to harm or even kill.  For example, what parent hasn’t made it a priority to teach their children the difference between harmful fungi and edible mushrooms.  Indeed to the extent that most of us would think long and hard before eating any fungi found in the wild unless we were 150% certain it was edible.  Look at the following picture.  Your instinct tells you if it’s safe to eat or not – it’s not!

So early man became over-sensitised to dangers to his health for his own good and continued existence. While modern man functions in ways almost unrecognisable from early man, that good old reptilian brain still is doing it’s best to protect us (flight, fight or freeze).  Think how we all respond to a sudden alarming sound, such as a gun shot or a scream, to know that the old reptilian brain is still alive and well.

Thus while all of us hate negativity we all seem to have this fascination with doom and gloom – just in case it helps us and our loved ones survive.

Back to Jon Lavin.  He makes it very clear that anything more than a small amount of ‘doom and gloom’ speaking to our consciousness increases the odds of depression and introversion.

Thus the message is that we humans should allow our Neocortex to tell our Reptilian ‘neighbour’ to go easy on the bad news, go and open a beer and watch the world go by! Whoops! Watch the world go by with a smile!

Oh, and Happy Valentine’s Day to you all.

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