So we're going to be dealing now with nature's agenda. Nature has a scheme in mind for the awakening and developing of this incredible intelligence and the eventual development of this exciting intellect. Nature's agenda is very simple. Let's take for example, and this is my old favorite, some of you have heard this one before, of the physical unfolding at birth, no teeth we hope. The nursing mother says she hopes. Around the first year of life we have what, the appearance of baby teeth and then we have the six year molars, 12 year molars and around 18, that misnomer, called wisdom teeth. So, periodic unfolding of physical development. Exactly the same thing happens with the periodic unfolding of blocks, intelligences or abilities and we find these directly connected with certain areas of the brain that translate those abilities.
Now let's look at this from the standpoint of the Piagetian stages, which he really got from Maria Montessori. Rudolf Steiner came to the same conclusions even earlier much earlier than Piaget or Montessori, and these are, let's just list them right quick, we have the stage that begins at birth, age one, four, seven,11, and at 15, which Piaget and most of the developmentists say the show is all over, development stops and we're stuck with what we've got for the rest of our life.
Now recently, in 1974, Herman Epstein claimed that evidence -- he's at Brandeis, that there are brain growth spurts at each of these periods. Now we know this is true. What these growth spurts? They are not necessarily the growth of new neurons the brain. You know neurons; they used to call them the thinking cells of the brain. We find that a single neuron is useless. It can't operate. It can only operate as it connects with other neurons.
And so we find that the power of the brain system doesn't lie just in the number of neurons but in the number of connecting links between them. Now these are what they call the axons, that branch out and that all the little branching dendrites that connect with other dendrites, we call them synaptic thresholds. You know all this from basic anatomy.
We find the growth spurt at age one, very large growth spurt. By 18 months of age for instance, the little toddler has as many neural fields available about the same neural weight available as we have as adults. Okay? Remember that. As we have as adults. Now, there's another growth spurt at age 4 even more neural connections. And then another huge one somewhere between 6 and 7. By that time the infant, I mean the young person, has five to seven times as many neural fields available as we have as adults or as they had at 18 months of age.
Why? Because we're opening up at age 7 to the entire possibilities of the great new brain. The biggest structure in our system and its abilities are totally infinite. Now, to get ready for that you have this huge brain growth spurt.
Every time we move into a new block of intelligences or abilities there's a brain growth spurt growing billions and billions and trillions new neural connections between all these for us to make a new block of learning and intelligences and adaptations as we translate from fields of potential into our actualized experience. Got it? Now, this is critical.
So that's nature's agenda to open up these blocks of intelligences one at a time as appropriate to the system and if we give a nurturing environment and provide the models for both that are appropriate to each of these stages. You never teach the child anything. They immediately absorb from their environment everything they need according to appropriateness because that's what intelligence is always doing.
We find in this that there is topology of the brain. By that I mean there's a certain mapping of the brains areas and we find certain areas that are devoted to or predisposed to handling certain types of intelligences certain kinds of abilities, instincts and so on. And that these must be opened, one at a time, to be appropriate, according to the needs of the whole system. We'll talk about that when we look first at the triune nature of the brain. Now triune, isn't that, it's like the trinity it's a rather awesome term.
This was the work of the brain research doctor Paul MacLean, at the National Institute of Mental Health's huge center for the study of the brain in Washington. And MacLean over a period of many decades, putting together both the massive research they were doing and research from all over the world came up with this triune structure of the brain. Everybody recognizes the triune structure of the brain. It's inevitable. It's there in the very physical makeup of the brain, but MacLean made a kind of -- did a no-no in the scientific world when he assumed tremendous profound meaning in these structures. Now science never deals with meaning. That's meta-physical. And MacLean did. He said no this has profound meaning for us because each of these different 3 levels of the brain has a different block of behaviors in it, you see, and that was the main contribution.
Let me just examine these right quick now. Now this again I'm making a cartoon and doing grave injustice MacLean's work. The first brain that we deal with now Karl Pribram spoke of this first brain which we call, MacLean calls the reptilian brain. Kark Pribram didn't like that he said no it's an amphibian brain. I said, oh thanks I need that kind of clarification. But at any rate, it was the oldest brain system developed in nature. The brain system developed through the great reptilian period, hundreds of millions of years in development, a long time ago, and we are the inheritors of that. This is the brain as Karl Pribram said that presents us with our physical world. Presents us with the physical world and knowledge of the body and our ability to interact as a body with the body of the whole world. That's what this most primitive and an ancient and primary brain is all about and that is that physical brain has a bunch of behaviors in it that are inherent within it. That is a bunch of intelligences if you like.
They're all designed for maintenance of our physical system, maintenance of the body and our species continuity. So we find this physical brain that gives us our awareness of an external world and our ability to interact within. It is the one that maintains this body and the world, drives for food, drives for territory or nesting you might say and for species perpetuation. Which in us translated that these higher systems comes the marvelous world of sexuality. And the snake and the reptile, it's very cut and dry, rather unemotional thing. In us just the opposite. Now once nature -- this is our wake state brain. Unless this brain is active we go to sleep and dream and all of that. When it's active all the rest of the brain alerts to what is coming in presenting the world out there and makes a response to it.