Put rather bluntly, we all have a reptile brain, called the hypothalamus, that controls the hormones of our endocrine system: This brain is about the size of a walnut and It has been programmed by millions of years of evolution to ensure the survival of the species: It keeps us alive when in a coma and it is responsible for most of our moods and animal instincts but we cannot think with it and it has no moral conscience.

However, the neocortex that has formed over it and which we refer to as our brain - as though it is the only one - can be educated to counteract some of the undesirable effects of the Hypothalamus. These are facts stated unscientifically and with limited scope but facts none the less.

It is obvious that education is the only means available to us to correct any excesses of the hypothalamus but this education must be well targeted. History has shown that dogmatic religious education can lead to even worse excesses such as the Inquisition and the Witch Hunts.

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Published in Interesting Stories


  1. roseinbloom

    Rodger, your blog is interesting but, could you share something that the reptile brain has caused you to do which would clarify how the reptile brain works in our lives.I guess we could all use our imaginations. I would like to hear yours.

    1. rodger Post author

      Roseinbloom. My hypothalamus keeps my body temperature and pressure stable and adjusts them to face-up to any sudden demands. It regulates the sugar level in my blood and it has many other functions that are essential to my physical well-being. Furthermore, it kept all of my bodily functions in good order through two operations while under anaesthetic. In fact, wherever a hormone is acting in my body it is my hypothalamus that is in control.

      1. roseinbloom

        rodger, when we talk of the “dvil on our shoulder” we are usually not referring to the normal life function but our sexual drives and other uncontrollable shens drives that overrule cognition. I was confused by the “devil” word.

  2. starlette

    Hello Rodger, your brain far excels mine in many ways…I guess it comes down to our own individual interests what our brain takes on board…….well do you think it is possible for everyone to be brainwashed ?…….I know not everyone cannot be hypnotised……I know I could never be……so what’s your take on that….

    1. rodger Post author

      Starlette: Yes, I do think that some people can be brain-washed when rendered weak by harsh treatment or drugs but difficult if the subject has full possession of his/her intellectual powers.

  3. missyu

    Rodger, why do you call it ‘ THE DEVIL ON MY SHOULDER’? It controls so many other important functions of the body. that I don’t see as reptile, but ordinary daily functions that are a must for the body to function normally. just thought I’d ask the question….*miles of smiles* … missyu

  4. Ms. K.

    This explains why the reptilian monster in the movie “The Relic” was attacking people and sucking out their hypothalamus! interesting.
    The movie didn’t do justice to the actual book by Preston and Childs.

    1. rodger Post author

      Hello Missyu; The fairy story goes that we have a devil on one of our shoulders and an angel on the other who counsel us and are responsible for our sins and our good deeds but are often in dispute. You are so right that the human hypothalamus is of more use to us than one might think. In fact without it we would not exist.

  5. vonMichael

    Hi Rodger,

    as you say; brain has been programmed by millions of years of evolution?

    Well how do you explain the fact that each of us can meet so many during
    the day who’s brain hasn’t even started the evolution! Michael

    1. rodger Post author

      Michael: I am not quite sure whether your remark is made in fun or not. It is true that many people give the impression of being mentally vacant especially when mesmerised by a finger-dabbing gadget. For them, I fear, evolution is too late. LOL.

      1. vonMichael

        No Rodger I’ve made it not for fun. Really not. When I see those
        hell driver fighting for seconds on our streets than my answer makes
        When I see and hear what is going on in Arab-countries ( no comment!)
        and so on. and so on. Regards Michael

  6. rose1943

    I love the last paragraph, Rodger. It indeed led us to the horrors in Salem, MA. as well as much of the learning I experienced in a Catholic school at a very young age. The movie “Doubt” shows ‘how it used to be’ and much has changed since then.
    Being cognizant of the reptilian brain is much of the battle. So glad you brought this up. Thanks for this.

  7. LoneRogue

    From your comments here it could be assumed that every one’s hypothalamus has the same programming. If the information it contains an transmits to each of us is identical whey do we act in different ways to similar situations?

    I realize that your comments are brief and I have so little knowledge of this subject that I am not taking issue with anything you have said. I merely do not understand how in our bodies lies programming that we ourselves have not experienced.

    Is this the source of dejavoux?

      1. rodger Post author

        Lone Rogue,
        All that we inherit from our parents at conception is part of our evolution but that does not mean that we should always look like and act in exactly the same way as they do. Every mood due to the hypothalamus can be moderated, suppressed or accentuated by the education received by the neo-cortex. For example; A small quantity of the stress hormones adrenaline and noradrenaline secreted into the blood gives rise to anger but our education will enable us to shrug our shoulders and keep calm rather than smash a few plates and commit mayhem.

  8. Rockflower

    Rodger, I am aware of what this part of the brain does regulating our involuntary functions that as you say keep us alive. I believe it is also responsible for some…. instinctive actions? Such as when we suddenly somehow become aware that we are being watched and look about. How we can be suddenly awake, no sound but perhaps we detected unexpected movement. But I am interested that you associate it with evil. I fully confess I don’t fully understand I am trying to work out my solution and will be interested in your comments.This so called ‘reptilian’ brain has been with us from way back in our evolution. It is the instinctive animal part of us. I look at animals and their instinctive behaviours, which are often raw and can appear cruel to watch. They have to eat, to eat they have to kill to eat. Yet I don’t think of wildlife as evil. Some animals can get into a so called killing frenzy. Their motivation to kill triggered by…….smell of blood, the realization that they are confronted by a weak or injured prey. Is this evil? I don’t know.It seems to me that evil requires some reasoning. For instance I can understand in a moment of great danger a person might have to kill rather than being killed. Is such a person truly evil? On the other hand if you capture someone and plan how to terrify that person or creature , how to cause maximum pain I think that is evil. Are you saying it is this ancient part of the brain that allows a person to do such a thing. I do believe that people who want to practise evil, look for an excuse and such people often cloak themselves in a distorted religious view. We are certainly seeing this in the world at present.

    1. rodger Post author

      Rockflower: I have avoided the word evil and used the word devil instead because of the analogy with the devil and the angel in the fairy tale. The word ‘evil’ and even the concept of evil is subject to fashion and can be interpreted in many ways.
      My cat will pounce on a passing mouse and will “play” with it before killing it. The cat is obeying its instincts because it has no neo-cortex that can be educated with notions of good and bad. I cannot blame it but I try to discourage it by feeding it well. However, the production of cat-food involves organised butchery so I am shifting the blame onto other shoulders. Human hunters do the same thing when chasing a fox with hounds but they do not have the excuse of not having a cortex …. or do they?

      1. LoneRogue

        This is interesting and some of the things said about this brain are difficult, for me, to grasp. I think how “can this be other than theory”. Has there been research which has proven this?

        1. rodger Post author

          LoneRogue, It is a logical sequence that theory should be proved or disproved by research.
          Having passed most of my professional life in a Physical Research Laboratory I soon learned that any project should be preceded with forethought. I am sure that Darwin did not sail off on his voyage without any idea of what he was looking for.
          What has been said in my blog posts is based on reliable information that is available on the internet.
          Thank you for your interest.

          1. LoneRogue

            You did of course say… “These are facts stated unscientifically and with limited scope but facts none the less”

  9. davidrv

    Interesting blog rodger.
    I was just thinking, as I always do it seems, that the hypothalamus stores all the threats that you have encountered in your personal life that has caused trauma. Unknown threats (to you at the time) that have caught you by surprise, as a bite from a dog, a burn from touching something hot. It doesn’t have to be cruel in nature, it has to startle you to the point that you don’t trust anything that seem to follow that same pattern.
    I think that the hypothalamus is your first line of protection, your instinct. If I see a bear 1000 feet from me, in the safety of my vehicle, it’s not the same as if I was startled by its presence just a few hundred feet away while walking in a trail. I don’t think that I’d be admiring the color of its fur or the strength of its limbs or how beautiful it looks against a colorful fall tree.
    These are just my thoughts for now. I don’t know if I really want to know how it works, as long as it does its job.

  10. Rockflower

    I think I agree with you Davidrv, I don’t think of the hypothalamus as the place for the devil. I think of it as housing our basic instinct for survival.amongst other functions. I think the devil needs knowledge, Adam allowed the Devil in when he bit into that apple LOL! Which kind of brings us back to religion Rodger.

  11. rose1943

    I believe the hypothalamus produces the hormones that run our bodies that we need for life….as Rodger said. I would be interested to find out if it is effected by ‘brainwashing’ or by ‘hypnotism’. Or how it would be effected.???

    1. rodger Post author

      jessamyne. Yes, I have time on my hands. Some time ago I posted a blog that I am filling in my retirement and keeping my mind active by designing a mathematical model of human behavior. It must be successful from that point of view since I have arrived at my 99th birthday with all my marbles both physical and mental.
      During the thirty-odd years since my retirement I have continued to learn and I have studied, dilettante, the subject that we are discussing.
      I appreciate your interest but regret that you have no further comment. Regards.

  12. jessamyne

    That was a rude comment on my part. For that, I apologize.

    From what I’ve read, evolution of birds and mammals from reptiles is an interesting theory, but, as always, high in conjecture. There are several supporting arguments for and against, including behavioral aspects as well as physical.
    You are right; the hypothalamus dictates a body’s status quo. It enables living beings to recognize basic need instincts, as well as higher functions, since it is linked to the pituitary.

    Thank you for bringing an interesting topic to light. I was encouraged to educate myself on a fascinating aspect of science.

  13. rose1943

    I posted a question on this blog a while back, Rodger. Someone commented about too much time on our hands. You answered her, she answered you, you got back to her and so on and so on.
    My question still sits there unworthy to be answered?

    1. rodger Post author

      Sorry Rose. No, I do not think that the hypothalamus is affected by brain-washing which is what one might call an operation on the intellect. However, the cortex is affected by the cortex so it is possible that there may be a secondary affect. An angry thought cthough may cause the hypothalamus to secrete n brain a

  14. roseinbloom

    Rose you shared good insight, but your question is very difficult to answer because it is not usually included in scientific study of the brain. I would tale a giant leap and say that hypnotism and brainwashing occurs as part of our cognitive functioning instead of the biological functioning parts of the brain. I am surmising and have not studied brainwashing or hypnosis as to the brain parts involved. Naturally, some aspects of all that happens to us, happens to every part.
    Rose, I have tried to answer, and I will study further on your answer.

  15. rose1943

    Thanks, Rose, I should study up on it too I guess. Right now it’s plumbers, carpenters and Christmas decorating in between. Yikes!

  16. rodger Post author

    Sorry Rose. A reasoned reply to your question requires a lot of reflection that I have not yet given it. No, I do not think that the hypothalamus is affected by brain-washing which is what one might call an operation on the intellect. However, the hypothalamus is affected by the cortex so it is possible that there may be a secondary affect. For example, an angry thought though may cause the hypothalamus to secrete the anger hormone.

  17. rodger Post author

    To all who are interested in their hormones.
    I feel that I was wrong to have referred to the hypothalamus as a brain; It is more like a regulator that compares the various constants of the body such as temperature, blood pressure, sugar levels, etc with reference values that are implanted in it: It then sends a correcting hormone signal to the gland or glands that are concerned with that variable.
    These are feed-back loops that do not require any intelligent intervention. There are many feedback loops at work in our bodies, some positive such as the relaxation of the heart. The hypothalamus has no conscience nor does it need any.
    This is the domain of Cybernetics which probably explains why this aspect is neglected by medical science.