The Rise of a Precept

Prior to 600 million years ago, all life on this planet was single celled. For nearly 4 billion years, all that existed were microscopic organisms living in the oceans. Then a revolution took place during the Cambrian Period. A mechanism kicked in that allowed small groups of cells sharing the same genetic material to begin to intimately cooperate with one another.

At that point, life was lifted to a new level of development. In this realm, not all cells were islands unto themselves. Some found that they existed in cooperatives that gave them the opportunity to specialize. In this situation, cells could focus on a subset of the tasks needed for survival, leaving the rest to others of the group. Many levels of differentiation emerged, but the most important of these specializations was the rise of messenger cells.  These cells sent signals throughout the organism by means of electrical conductivity. In their aggregate they gave rise to the nervous system.

Early on in this differentiation process, an advantage arose from not only employing diffuse signaling, but by providing aggregation points. The linking of a number of messenger cells into tightly communicating groups produced the central nervous system. 

The Start of a Biological Precept

When the earliest aggregations of messenger cells emerged over 500 million years ago, these neural centers where both small and of limited capacity. Yet for all their limitedness, those early central nervous systems still had to justify their existence. They had to improve, right from the start, the survivability of the organisms to which they belonged. By what we know of such systems today, there were two means by which this could be done.

The first mechanism was internal homeostasis. If an organism were to get out of internal balance, electrical conductivity could speed up the processes of recovery far faster than diffusion of chemical messengers alone.

The second mechanism for a central nervous system that would justify its existence was to allow various types of information from the outside to be brought in and processed through a kind of parallel logic. The output of this repetitive logic would have been wave upon wave of signal patterns. These signal patterns would have propagated through the organism producing specific reactions that, in some cases, would change the organism's relationship to its surroundings. This logic-driven behavioral mechanism could then be programmed by natural selection.  This would allow a given species to develop, over time, actions that would better meet the survival needs of the individual.

This type of small, straight-forward processing center offered such significant survival value that it has persisted for more than 500 million years. Today, there are millions of species that make use of it. One of the smallest of these systems is found in the ubiquitous mosquito.

Growth of a Biological Precept

What we know from Darwin is that once a beneficial biological mechanism arises, two things will develop: First, the expression of that mechanism will grow in numbers.  Second, it will increase in diversity. 

The central nervous system was no exception. Fossil records indicate that it was one of the quickest evolving systems on the planet. Now, 500 million years after it emerged, it has been carried to its newest extreme. As a set of species, the warm-blooded mammals have the greatest brain to body ratio ever seen in the history of life. Within that extreme, the human species sits at the far edge of the spectrum; our brain to body mass is the greatest yet.

A Biological Precept

From our study of life, our species has learned that there are a range of precepts, or rules, that have been in operation in the development of these various complex systems. The one rule that we at Core Memory Circuits have found valuable in moving digital science forward is derived from the study of the various types of central nervous systems.

This rule begins by recognizing that regardless of whether it is Boolean logic used in our silicon-based systems or biological logic found in central nervous systems, several major points can be made about the use of discrete logic.

First, when developing early expressions of computational systems, repetitive logic is the only path to their creation. Repetitive logic is simple, effective, and with very little resources, it gives you big results.

Yet, regardless of the path taken, either through natural selection or human engineering, you eventually run into the second truth about the use of repetitive logic. There is an ultimate limit to how far it can be made to scale. Beyond that point, it becomes too much of a power hog. As for why it becomes a power hog, that is an in-depth discussion that will be given at some future time. Suffice it to say, parallel-based biological systems are superior to Boolean-based logic systems. Consequently, IBM has initiated a major program to bring biological type processing into human machinery. But both approaches do reach limits in their ability to support the growth of computational systems.

If the human brain ran solely on the mechanism of repetitive logic, it would burn itself up very quickly. Since we are here, it is obvious that something else is at work to allow us to have the computational capacity that we do.

What then is the solution? If each of us gave this subject a few moments of thought, it would become obvious what mechanism dominates our mental activities. To highlight the difference between the various types of central nervous systems, consider the two ends of the spectrum, the flatworm and the human being. 

In its environment, the flatworm spends most of its time moving about, looking for the necessary nutrients to survive. As it moves, its little central nervous system never has such a thought as, "Well, I was at this very same pebble last Thursday. And, if I remember correctly, if I turn to the left by about 32 degrees and go 25 and 1/2 inches, I will find some very tasty food." This is not what happens in these simple animals. Rather, they receive a wide range of sensory inputs that are continuously monitoring such things as chemical gradients, moisture levels, light intensity and temperature. All of these inputs come into its aggregation of messenger cells where continuous repetitive logic is applied to them. The ongoing results of this computation steadily direct the organism through its environment.

Now consider ourselves. We, as organisms with one of the largest central nervous systems seen in nature, are always keeping a mental map of where we are, both in time and space. Within this framework, we do have thoughts such as, "Well, today is Thursday. And my favorite restaurant is having one of their tastiest dishes on its special menu. If I turn left at the next light, go down two blocks, cut across Fifth Street and up that little alley, I can make it there before the dinner crowd hits at six."

We, like the flatworms, have a very large number of inputs coming into our central nervous system on a continuous basis. And like the flatworm, these inputs keep us anchored to our world. But that is where the exact comparison ends. We still find that there is a range of repetitive logic systems taking place to filter these inputs within us. These logic processes occur deep below the surface of our awareness. The results of these logic processes must work their way up through layers of mental activities that make up our subconscious.  Eventually, some of these inputs, in highly modified form, do have impact on our behavior. But unlike the flatworm, these autonomic conclusions are not the final arbiters to our actions.

In the above example, the trigger for the actions might have been the result of incoming smells from a hotdog stand combined with our internal energy measurements. But it is not chemical gradients that direct us to the food. That is determined by a much more powerful mechanism. That mechanism is a form of memory.  You can also notice in the above mundane example that it was not just one memory that directed the individual to his goal. Rather, it was a number of discrete memories working in concert--starting with what was around the next corner and ending with the memory of crowds--that directed and controlled the complex behavioral pattern.

This brings us to one of the major precepts of modern physiological psychology. With simple organisms, repetitive logic is the only mechanism in operation. As you move up the animal kingdom, you find that at a certain point in the size and intricacy, a higher-level mechanism begins to emerge. This mechanism does not replace the more basic mechanism. Rather, it works in conjunction with that mechanism in order to amplify what the animal can do. As the organism becomes ever more advanced, interactive memories become more and more the dominant mechanism in the central nervous system.


Return to Engineering
Footer