The Neo-Darwinian theory of evolution by natural selection, or the 'Survival of the Fittest,' coupled with the idea that mutations of the genes occur in accidentally advantageous steps, has been under attack recently. But there is no doubt that in its original form the theory was valid. Darwin originally postulated that changes in the natural environment meant that individual animals with particular characteristics were better fitted to survive and therefore bred in greater numbers. This undoubtedly happens within species but in the wider context does not adequate explain how entirely new species of animals can emerge, neither are all the intervening steps present in the fossil record of history, as they should be.
Nevertheless, evidence for successive evolutionary leaps having occurred in the genes of primates, particularly human beings, is demonstrated by the various changes undergone by the embryo in the womb - which resembles in turn a fish, a reptile and finally a primate. These species are so different that the steps necessary to produce such quantum jumps of differentiation would require three successive acts of creation - not just one.
There is thus throughout the evolutionary process, evidence of earlier structures embodied within the later species, evidence of earlier types of creatures having been modified, improved, added to in a dramatic way. In no place is this process more marked than in the most complicated structure of all - the human brain. Here are contained at the very least three overlapping developments of more primitive types of brains which existed in more primitive creatures.
According to generally accepted anthropological findings, the anatomic evolution of the human brain was virtually complete around 50,000 years ago. Since then the human brain has remained essentially the same in size and structure. On the other hand, the conditions of life have changed drastically during this period and continue to change at a rapid pace. To adapt to these changes, the human species used its faculties of consciousness, conceptual thought and symbolic language to continue to advance by means of social (rather than genetic) evolution. However, this kind of adaptation was by no means perfect. We still carry around biological equipment from the very earliest stages of our evolution that tend to pull as back to the state of consciousness of our mammalian and reptilian ancestors.
The neurologist Paul MacLean has proposed that our skull holds not one brain, but three, each representing a distinct evolutionary stratum that has formed upon the older layer before it, like an archaeological site. He calls it the "Triune Brain."
MacLean says that the three brains operate like three interconnected biological computers, each with its own special intelligence, its own subjectivity, its own sense of time and space and its own memory. He refers to these three brains as the Neo-Cortex or neo-mammalian brain of the frontal lobes of the cerebrum; the Limbic or paleo-mammalian system of the mid-brain and thalamus; and the Reptilian brain - the brain-stem and cerebellum. Each of the three brains is connected by nerves to the other two, but each seems to operate to some extent independently, as its own brain system with distinct capacities. Note: only humans have significant frontal lobes, which play a key role in many thinking processes that distinguish human beings from other animals. The frontal lobes are particularly important for abstract thinking, for imagining the likely consequences of actions, and for understanding another person's feelings or motives. Injury or abnormal development of the frontal lobes can result in the loss of these abilities.
This hypothesis has become a very influential paradigm, which has forced a rethink of how the brain functions. It had previously been assumed that the highest level of the brain, the neo-cortex, dominates the remaining lower levels. MacLean has shown that this is not the case, and that the physically lower limbic system, which rules emotions, can hijack the higher mental functions when it is aroused by an appropriate stimulus.
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It is interesting that many esoteric spiritual traditions taught the same idea of three planes of consciousness and even three different brains. Gurdjieff for example referred to Man as a "three-brained being." There was one brain for the spirit, one for the soul, and one for the body. Similar ideas can be found in Kabbalah, in Platonism and elsewhere, with the association spirit - head (the actual brain), soul - the heart and emotions, and the body corresponding to the solar plexus.
Each successive layer of the Triune Brain contains a progressively more complex infrastructure of nerve cells, and the neurons which connect them are terminated within the three levels, almost as if the higher functions were tacked on as an afterthought.
Looking at the nature of these interacting systems one cannot accept a "single creation" viewpoint - that is, a theory which suggests the human brain was created complete, as a single project. No one would have done it this way, putting in clumsy, old-fashioned brain cells, overlaid by newer and more effective ones . It would be rather like mixing up microprocessors with thermionic valves in a new hybrid type of computer. The brain clearly shows evidence of different periods of ancestry in its component parts, and these ancestral relics naturally produce different modes of thought. We all embody the intentions of earlier creators. If "creators" have to be inferred, it seems they did not design completely new creatures at each step in evolution, but instead took some promising animal and improved it by grafting on elements of a new brain, as well as altering the body. Such changes did not automatically increase its chances of survival, so Darwinian theory has to be suspended for a period. Let me explain...
Grafting a Mid-Brain onto a creature which functioned merely by stimulus and response according to a genetic pattern of behavior enabled the new creature to profit by its experience and alter its responses to suit certain circumstances which had occurred in the past. But this learning from experience took time. Initially the new creature would just have been uncertain and slower in its reactions than a more simple organism. Eventually the new animal would gain an advantage by considering carefully what it did, altering its responses so they were always appropriate to the situation, thereby saving energy which had been wasted fruitlessly in automatic reflexes.
The inescapable conclusion is that a new species which involved one of the quantum jumps must have been able to occupy a unique habitat for a while, where it was safe from predators - a Garden of Eden.
In the primates there is a third stage, the mediation of automatic action and reaction by experience. Beyond the old reptilian Mid-Brain, the Hypothalamus and Rhinocephalon, there are the Neo-Cortical additions of reflection and memory, which make possible a much clearer interpretation of information from the environment. This type of brain can not only act from memorized experience, it can also devise strategies for dealing with situations that have not occurred before, or that may occur in the future. It epitomizes the triumph of optimism over experience and it has an inbuilt purposefulness to devise ways of surviving with less danger or exertion.
While the older part of the 'reptilian brain' is clearly outclassed in all these areas of thinking, it still remains fully functioning and is essential for maintaining contact in the areas of touch, taste and smell. But this does not see consciously like the Neo-Cortex, it reacts to a sensation of seeing things in merely symbolic shapes, which invoke standard responses. The Neo-Cortical centers are more flexible in function; they grow connections in relation to hereditary dispositions and environmental influences, they can displace functions in response to injury and decay, and they have a vastly greater capacity for the inter-relation of knowledge.
In general terms one can distinguish the double-think of the mammalian Neo-Cortex from the Primal thinking of the ancient Reptilian Mind, in the way that cat, dog, horse and dolphin will eat from your hand by finely controlled movements of the jaw and tongue, while the shark and alligator will have your arm off along with the proffered food.
The fastest brain rhythm is that of the lowest center, the Cerebellum, which can make a response within 2 milliseconds, quite close to the limit for a nerve fiber. The mediated response of the Neo-Cortex generally occurs in about 50 milliseconds. A state of arousal of the whole brain requires about 200 milliseconds.
The triplicity of Neo-Cortex, Mid-Brain and the Cerebellum reflects the triplicity of many aspects of philosophy and religion; also the trinity of Ego, Superego and Id in Freud's psychology. Freud inferred that the parental prohibitions of childhood gave rise to the Superego; this is a form of learning by experience which is not a higher kind of consciousness but more closely related to mid-brain emotional inhibition. The Id functions through the most primitive part of the brain, an inbuilt and automatic response to the needs of the body. On seeing food the mouth waters, on feeling pain it withdraws, when needing pleasure it indulges. It is Hedonistic with no consideration of morality.
The child psychologist Piaget carried out studies which showed that in the first three years of life, babies go through what he called the 'sensori-motor' phase of thinking. They react to events around them without stopping to think. These reactions are very quick and a favorite vase is toppled in the flicker of an eye. When the newer parts of the human brain are sufficiently developed to act as a 'center of intention' there follows a phase, from the age of three to about nine years , where the child learns from experience and becomes more deliberate and purposeful. This is the phase of 'concrete operations' which involves manipulation of physical objects in the child's surroundings. The final phase occurring after the age of nine involves the Neo-Cortex. Subjective thought, insight and creativity emerge, the ability to make plans for the future.
Our Reptilian Mind does not stop working as the higher mind of the Ego develops, it is still fully functioning in every adult. The Neo-Cortex soon tires when starved of essential nutrients. When, through overwork, stress or intoxication we let slip the mask of the kind Dr Jekyll, the demon Hyde appears with his Primal thinking to lash out in some thoughtless act. Punishment for such uncontrolled 'bad' behavior as a child teaches us to repress the Reptilian Mind side of our nature. Some go to extremes and resolve never to lose their cool, so they punish themselves by an extremely tight control of their animal passions.
This can produce what is technically known as the 'Gooch Split' (after the work of Stan Gooch), a vertical divorce between the higher and lower centers of the brain - the 'mind-body split.' This is a recipe for psychological neurosis. The Superego changes its role from that of conscience to a cruel taskmaster placed in charge of the forces of the Id, which have great power and cannot be repressed indefinitely since they supply the basic drives and motive force of the personality. The Id will try to reassert itself by manufacturing strange dreams and even physical symptoms. If the conscious mind ignores the warning signals then the Id will begin to twist the person up to the point where they feel continuous pain and join the multitude of people suffering from a psychosomatic disorder. We must learn to accept and understand our drives and primitive feelings, so that we can control them rather than suppressing them, in order to be able to heal the 'Gooch Split' and get all parts of the brain and personality working together harmoniously.
In this kind of communication attitude is important; one must not despise or fear the Reptilian Mind within - it is a basic part of your being; you cannot deny part of yourself, shut it away or forget it. It knows everything you do or think. As we develop we learn instead to treat the Reptilian Brain as our pet, a thing to be fed and watered, taken out for exercise, humored and played with, stroked and petted.
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The Reptilian Mind has appetites which are basic and powerful. They cannot be denied and one should not be ashamed of them. Instead one should use them by converting the energy they release for our intellectual and creative needs. The Reptilian Mind loves excitement - people love to indulge in dangerous sports like mountaineering, surfing, racing, skiing and hang gliding, because this helps to placate the Reptilian Mind. We should choose therefore to play some physical game or master a physical skill since this puts us more in touch with our body, and therefore more capable of good health and recovery from injury.
One should beware becoming bound up in cerebration, with thoughts unrelated to their application. Mental effort without corresponding action by the body is not understood by the lower mind. So, if you are trying to work on a difficult problem always try to write it down or draw it in the form of a diagram, with little arrows and explanatory symbols. The Reptilian Mind cannot read but it loves picture books. Why do we use symbol signs on the motorways? Perhaps driving brings out the reptilian nature in us all.
We must be attentive when the Reptilian Mind tries to speak to us. The symptoms are usually the sudden onset of clumsiness or accident-proneness, butterflies in the tummy, hot flushes and catching of breath, and the racing pulse. These are the alarm bells ringing and we should try to discover what has upset the lower mind. The Reptilian Mind is trying to speak to us and we should listen and understand what it is saying.
What happens when we are over-stressed and overwhelmed by information input, is that a multitude of impressions get passed down from the higher mind into that ultimate sink for experience, the Cerebellum. It is diverted from its normal job of controlling balance and we stagger about, amazed at our clumsiness.
While we dream, the Reptilian Brain is in charge of our automatic activities and it uses the opportunity to give us messages. Cryptic and symbolic pictures in dreams are the messages of the lower mind and they are worth trying to interpret in the light of our past experience. We need to learn to be conscious of our higher mental faculties and to put them to regular use. The worst thing we can do is to so blunt them with intoxicants and drugs that the Reptilian Brain takes over and runs our lives.