5.2 A Sphere of Life in an ocean of uncertainties. Synergy guides growth.
Before we start studying the maps of the above mentioned systems that have specialised in learning (the lymphoid and the neural system) I want to account for the fact that these maps have a spherical form, and are divided in concentric zones that envelop each other.
The logic of evolution comes to the surface: create ever more complex assemblies in synergy with the environment (4.3). This is called differentiation (Map 5.2.1). The first clusters of cells in an early evolutionary stage were still rather homogeneous, like the amoebe's cell mass (3.1). In the course of evolution tissues differentiated, organs specialised in digestion, motion, defence etc.
Map 5.2.1: Synergy by two-way information transport
Concentricity is a device that reduces the complexity of the organism without resorting to an overly simple one-way hierarchy (Yakovlev 1970). In a concentric organisation the hierarchy goes both ways: from the inside outwards, and from the outside inwards. The central structures respond to environmental change with a long time-constant and impose their standard values on the peripheral layers. These have shorter time-constants, which enable them to respond rapidly to the environment while implementing the instructions coming from the central core.
Central structures have the following properties:
great stability because of strong molecular bonding
rapid chemical reactions between small molecules
slow oscillations, long term interaction with the environment: evolution, development, regulatory functions
Surface structures on the contrary show
great plasticity because of weak internal bonds between large molecules that allow conformational change
waves in the recognition network involving large quantities of matter and long circuits
fast interaction with the environment, cognitive growth (= learning by selective breeding)
When a core structure detects an incongruity with respect to its standards, it dispatches a message to it's neighbouring peripheral structure, which in turn starts operations to diminish the incongruity. The operant response needs some time before it will have reduced it's motivating signal; the higher the oscillating frequency of the corrective or regulatory circuit is, the shorter the time interval will be. Other oscillating circuits that also interact with the motivating parameter (the messenger of incongruity) will compete for effectiveness with the first circuit. The one that has the best adaptive effect will be the one most likely to be selected and to subsequently become a permanent part of the system.
Another result of learning is anticipating a need for adaptive action. Any change that is recognisable as a stimulus can, when it concurs with a message, become associated with that message. From then on, the message predicts the stimulus and sets the corrective actions in motion before the incongruity is actually noticeable. This is classical conditioning, or respondent conditioning. By this learning process the NAD learns avoidance and appetitive behaviour. It enables the individual to avoid impending negative (hostile) stimulation and to seek positive (feeding) stimulation from the environment.
To protect themselves living systems, from the most elementary to the most complex forms, employ two strategies that complement each other:
(a) adjustment: when a living system is challenged by its environment it responds by adjusting to the challenge. A succession of challenges exerts pressure for continuing adaptation and directs differentiation and increased complexity of function and form
(b) maintaining identity: the genetic system has set limits to the possibilities for change; individuals protect their 'self' and maintain their specific and individual identity against pressure to adjust to the environment.
The opposing tendencies for change (a) and resistance to change (b), are in continual dialogue. The synergy, finally reached by the pull of opposing fields, forces optimal growth and learning. The tendency to changeis necessary to optimally adjust to environmental requirements, such as protection against climatic change or a change in predator population. The genetic system offers a vast range for adjustment and individual learning. It also offers resistance to change because there is a limit to the range of genetic potential. This limit guarantees that eventual adjustments are in agreement with the master plan of the individual. The genome guards against weakening of identity by over-adjustment, which would lead an individual to disintegrate (as after repeated and severe emotional traumatisation, when an individual is compelled by force to forsake his identity).
Fig. 5.2.1 (at begin of this paragraph) represents the process of synergy. It summarizes the dialogue of nature (heredity) and nurture (environment) in development and learning. Because of its explanatory power, a sphere with concentrical layers is the appropriate model to represent the continuous dialogue of centripetal (nurture) and centrifugal (genetic) information pathways. The dialogue and the resulting synergy is characteristic for immune and neuronal learning within individuals. A spherical model with a core and various layers or growth-zones will answer such questions as: how an individual meets environmental challenges, how he learns to anticipate positive and negative events. For the sake of simplicity our three-dimensional sphere has been reduced to a flat disk. It is not even a full disk, only a partial cross-section of the sphere of a living system is shown, in the form of a sector, which leaves the rest of the disk invisible.
Map 5.2.2: Two learning systems
We see a curved surface: the boundary between the organism and its environment. It is the "surface-membrane" where the exchange of information between the individual and its environment takes place. At this level the LAD deploys its antigen sniffing lymphocytes, and the NAD its sensory scanning organs: smell, sight, touch, hearing. Toward the left of the diagram, the sides of the sector converge in the hub of the sphere. There, far removed from the surface, is the location of the inherited factors, which mark the genetic identity of the individual. It is called the genome and its material basis is the chemical building-code laid down by the DNA molecules. The genome constitutes the evolutionary memory and maintains the individual's identity against pressure coming from the environment. The continuous information issuing from the genome protects the individual against over-adaptation and the disintegration that would be the result.
The genome is the hard core of the individual that resists change and only adapts under long-term pressures in the evolutionary time scale. Fortunately it leaves room for short-term adaptations which we label as epigenetic or ontogenetic learning. Information about the environment, detected at the surface, is carried inwards where it meets the outwards directed information issuing from the genome. Genetic information is carried outwards to the external layers, where it engages in a "dialogue" with messages received from the environment. The reconciliation resulting from the interaction of opposing information streams is called learning. This may be the acquisition of new and meaningful cognition, or more differentiated skills, both of which will contribute to profitable adjustment while safe-keeping the individual's identity. On a global level, adaptive changes seem to be "instructed" by the environment; on the molecular level they turn out to be "selected" (Jerne 1967). In order to understand this, we'll turn once more to the immune system, since its development is exemplary for a learning process.
5.3 The lymphoid or immune system (LAD): a network of lymphocytes and antibodies.