Although we often refer to our brains as a single, solid unit, it is clear that this is not an accurate description. Rather, our brains consist of a conglomerate of various sub-brains and sections, all interconnected. Dr. Pau! D. MacLean, a prominent brain researcher, has developed a model of brain structure which he calls the "triune brain." In other words, humans have not one brain but three. (Actually, even this is an oversimplification; but this model has the adVantage of displaying our evolutionary heritage.) MacLean states that the human brain amounts to three interconnected biological computers," with each biocomputer having its own special intelligence, its own subjectivity, its own sense of time and space its own memory, motor, and other functions." Each of the three brains corresponds to a major evolutionary development and are categorized as follows: the reptilian brain the old mammalian brain and the new mammalian brain. MacLean illustrates this point facetiously when he points out that when a psychiatrist asks his patient to lie down on the couch he is asking him to stretch alongside a horse and a crocodile.
According to the triune model of the brain, evolution has simply added new sub-brains to preexisting ones like a man who keeps building additional structures onto an old house However, to continue with the analogy, with each new addition to the house the physical structure of the older components were altered or modified to some extent. In other words the reptile brain m humans is not exactly the same as the brain of a lizard. That is not to say we haven t retained any reptilian functions in our brains; we most certainly have. MacLean has shown that our reptile brains play a major role in our aggressive behavior, territoriality ritual and social hierarchies.
Thinking Animal Thoughts - TIME One medical theorist. Dr. Paul D. MacLean, has suggested that when a man lies down on a psychiatrist's couch, a horse and a crocodile lie down beside him. People, according to MacLean's theory, have not one but three brains: neomammalian (the human), paleomammalian (the horse) and reptilian (the crocodile). Certain primitive tribesmen make no distinction between human and animal life but assume that all life is roughly the same. It simply takes up residence in different forms, different bodies. Higher cultures do not make that organic assumption; they are haunted by the animal in man, by the idea of animals as their lower nature, the fallen part, the mortal. The clear blue intelligence of civilization, they think, is imprisoned in the same cell, the body, with its Caliban, the brute undermind.
That assumption is a bit of a slander upon the animal kingdom, of course. It arises from an egocentric and spiritually complicated habit of mankind. People use animals not only for food and clothing and scientific experiment and decoration and companionship, but also, most profoundly, for furnishing the human mind with its myths. Victor Hugo wrote, "Animals are nothing but the forms of our virtues and vices, wandering before our eyes, the visible phantoms of our souls." We become those elaborately varied creatures, we take their forms. Odysseus' companions were transformed into swine, but in the metamorphosis, their intelligence remained human, unaffected. In reality, when men are transformed into beasts, for whatever reason (anger, greed, lust, drugs), their intelligence is usually very much affected, for the worse. Unlike Odysseus' men, they keep their human forms but assume the character of beasts.