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THREE BRAINS: Kinglizard © 1981 rev. 2002

Despite the ruminations of philosophers and preachers, it seems apparent that the brain was neither carefully planned nor seamlessly executed. Evidence confirms that fact that it simply happened, and that lack of pedigree nullifies any expectations about the brain's configuration. Common sense might suggest that the brain is likely to be unitary and harmonious, but it isn't. A homogeneous brain might function better, but not a single creature upon this earth can be found to have such a brain. Even the simplest multi celled creatures show diversified structure in their neurological systems.

SO . . . The brain is not the result of some clever plan. It is a biological organ that evolved into a special function, not much different from muscles, lungs or liver. Generations of organisms adapted to fluctuating conditions, over eons of time, and evolution fostered changes. Many things, including chance and circumstance, serve to shape biology. Evolving biological structures do not obey the rules of logic, they simply follow the long chain of successful adaptations that promote survival.

One might be inclined to think of these adaptations as gradual and progressive, but this is not the case. Twenty five years ago, Niles Eldridge and Steven J. Gould argued that the fossil record shows a sporadic and uneven path for adaptations, rather than a series of smooth transitions. Evolutionary progress appears to be punctuated with bursts of metamorphosis. When the environment shifts or a favorable mutation arises, animals rapidly modify or new species explode into being.

The HUMAN BRAIN is structured similarly to all other vertebrates and consists of three distinct and separate evolutionary adaptations beginning with what we call the REPTILE Brain, overlayed with the LIMBIC Brain, and finally the Neo-Cortical Brain or Cerebral Cortex.

We see a clearly TRIUNE structure to the brain: Note the relatively similar size in the reptile and limbic brain as compared to the large disparity in the volume of the cerebral Cortex between other Mammals and Human beings.

THE REPTILIAN BRAIN:
The oldest parts of the brain are simply bulbous elaborations at each end of the spinal cord. This brain consists of neurons that control breathing, swallowing, heartbeat, and the visual tracking system a frog relies on, to snap a dancing dragon fly out of the air. Reflexes that prompt an instant reaction to specific stimuli are located throughout the body and connected through the spinal column to this primitive brain. In fact these reactions are the reason an animal has a brain in the first place.

The reptilian brain is the part of the brain that remains functional when a person is said to be "brain dead." As long as the reptilian brain survives, the heart will keep beating, the lungs will expand and contract, blood chemistry will be balanced, and body temperature will be normal. A body animated by the reptilian brain is not aware or what we term "alive" but merely living tissue and organs, regulated by the instinctive reactions of biology and neuro-chemistry.

The reptilian brain possesses motivators, but not what we consider "Emotions." The reptile brain permits rudimentary interactions with other animals, courtship and mating displays, demonstrations of aggression and territorial defense. Many reptiles attack and repel intruders, illustrating how primitive turf battles are in the history of territorial vertebrates.

When we see an urban gang, mark their domain and harass others for stepping into the wrong city block, or wearing a Blue shirt in a Red shirt area, we are witnessing, in part, a behavior motivated by this ancient brain and more suited to the world of the solitary non social reptiles that lived hundreds of millions of years ago.


THE LIMBIC BRAIN:
High school biology defines mammals as; warm blooded, having fur, and bearing live offspring. Reptiles are defined as cold blooded, having scales and laying eggs. These generalities do not begin to adequately or accurately describe the many and profound differences. As mammals split off from the reptilian bloodline, a fresh neural structure blossomed within their skulls. This new kind of brain transformed not only the mechanics of reproduction, but the orientation of parent animals to their offspring.

The French surgeon and neuro-anatomist, Paul Broka published most of his important findings in 1879. He showed that the brains of all mammals hold a structure in common. He called this the "Le grand lobe limbic" The great Limbic lobe. His dissections clearly showed a line of demarcation between this structure and the rest of the cerebral hemisphere. He coined his term from the Latin word "limbus" meaning edge, margin, or border.

The Limbic brain is a biological adaptation that occurred as mammals evolved from small lizard-like reptiles. It wraps around the bulbous reptilian brain at the top of the spine, interconnecting directly to the solar plexus at the base of the spine, through the spinal column. Within its smooth curves, lies a group of neural structures with tongue twisting names; Hippocampus, hypothalamus, fornix, amygdala, septum, cingulate gyrus, pirirhinal and perihippocampal regions.The peculiarly mammalian innovation of carrying it's developing young within a warm-blooded body, rather than leaving them outside in eggs, was well-established long before an errant asteroid rammed the Earth and destroyed the dinosaurs. But it's likely that the rapid extinction of large reptiles left a significant opportunity and the tiny Mammals scurried into the gap and literally, "multiplied like rabbits." The adaptations that fostered and sustained this expansion of influence are largely in the brain. Mammals bear their young live, and enter into elaborate and subtle interactions with them. They nurture, defend, and support them as they mature, in simple terms, mammals take care of their young. Child rearing and care taking are so familiar to humans that we tend to take them for granted, but these capacities were once novel, a revolution in social evolution.

We can see that detachment and disinterest mark the parental attitude of a typical reptile, it is no surprise when a reptile lays its eggs and walks or slithers away. But mammals form close knit, mutually nurturing, social groups. Families, clans, and tribes, where members spend much time touching, communicating, and caring, for each other. A Turtle or snake may watch the death of its kin with an unblinking eye, while a mammal may risk and sometimes lose, its life protecting its offspring or family. These behaviors spring from what we call emotions that arise in the Limbic brain.

Humans sing to their children. Vocal communication between mother and offspring is universal in mammals. Remove a mother cat from her litter of kittens and they begin an incessant yowling, the separation cry, this shrill distress call drills into the psyche of the human being, and we all recognize exactly what it means. A baby alligator has the ability to vocalize, but knows better. Most reptiles are cannibalistic and soon after her eggs have hatched she will become a predator to her own offspring, calling for mama isn't a part of the reptile's instincts.

Mammals are inclined to display what appears to be, uniquely useless, behavior, such as "play." Anyone who has played tug of war with a dog can clearly see that the dog doesn't really want the old shoe it's pulling at. The animal wants TUGGING, it wants the social interaction, and the delight of the game. Certainly this activity, or the game of "fetch," includes natural behaviors, such as chasing, hunting, and capturing, in their "rules," but the dog is fully aware it's a game. The animal isn't eating, or mating, or rearing its pups, It isn't hiding or fighting or doing ANYTHING that overtly seems useful. It is simply living with pleasure and delight, the chemistry of the limbic brain, allows the dog to become attached to its environment and its playmates.

The Limbic brain is, to a large extent, responsible for Mood, State of Mind, and even Self-Awareness or Sentience. One might say the Limbic brain is the FEELING BRAIN, a place where we experience "Vitality" or the unique sense of "Being" that makes us human. Emotions generated within the structures of the limbic Brain, tend to be the motivations for the most basic kinds of behavior. Emotional "Moods," such as, happiness, anger, grief, misery, love, or attachment to others, spring forth from this largely chemical mind. Instinctive behaviors, such as, mating, social bonding, nurturing of offspring, cooperation, and competition, are all results of the moods created by limbic chemistry and the "wiring" in the very early Mammalian brain.

While there is no doubt that Humans can LEARN to mitigate these moods and control the resultant behaviors, to accommodate cultural ideas and practices, the basic motivations and behaviors are largely instinctive and are biological adaptations that have served our species well, and promoted our survival, for millennia.

THE NEOCORTICAL BRAIN:
The Neocortex, (Greek for "new" and Latin for "rind" or "bark") Is the last, and in Humans the largest of the three brains. Like the rest of the brain, the neocortex isn't really completely understood, but science has made some progress over the past few decades to map the functions and capacities of this mass of tangled neurons.

Mammals that evolved long ago, such as the opossum, (which retains a pouch, allowing a kind of extended gestation period to continue after birth) have a very thin neocortical layer covering the older reptile and Limbic brains. Even today, one can observe how simple and instinctive their behavior patterns are. As mammals evolved larger and more convoluted cortexes, more complex behavior and specific adaptations for survival became prevalent. Many modern animals, including some birds, display complex attachments and social behavior that exceeds these simple mammalians.

In Humans, the Neocortex dwarfs the rest of the brain. It consists of two generally symmetrical sheets of neural tissue, roughly the size of a thick hand towel, crumpled and wadded together to fit over the reptile and limbic brains and tightly fitted within the confines of the skull. The cortex of a Human being is huge in comparison with even our closest Non-human relatives, the Great Apes.

We seem to have voluntary control of many neocortical functions. The basic stimuli of Vision, Scent, Touch, Taste, and Hearing, as well as our awareness of "self" or "Consciousness", all seem to be experienced in the Neocortex. We can focus our attention upon Speaking, Writing, Planning, Reasoning, Memory and Recall and "voluntary" muscular functions, so it's quite clear that a large share of our experience of living is influenced by this "Thinking Brain."


THE MIND:
Western cultures tend to glorify empirical knowledge and science, above intuition, spirit, and emotion. Albert Einstein warned, "We should take care not to make intellect our God; it has, of course, powerful muscles, but no personality. It cannot lead; it can only serve."

As a Scientist, I find myself constantly seeking to understand the biological complexities of the Brain. This organic "Machine" can now be probed with precision tools that reveal and describe it's biological functions, but the MIND is something beyond the Brain.

Reason, Logic, Knowledge, and Memory are experiences we lump into what we call intellectual awareness, but the focus of our attention and the quality of our intention is strongly influenced by ancient, limbic brain chemistry.

SENTIENCE or Self Awareness, must include motivation. To fully experience being alive, one must allow the power of mood, and emotion, created within the limbic mind, to permeate every facet of life!

Buddha, advised his followers to seek the truth about the Universe and our place in it, through Attention and Intention. That is; to EXIST through awareness of every facet of the universe (Pay Attention!) And, to influence that Universe through our unique ability as sentient creatures with "good" Intentions. He opined that we are not separate "things" from the whole, but are "Stream" that is; totally attached and involved with every other thing in the universe.

Perhaps "MIND" is the music played upon the instrument that is the "BRAIN." Maybe If the instrument is fully understood and one practices diligently, the Music will be sweeter and more meaningful.