We experience Time in more than one way. Linear time moves forward, like an arrow flying, irreversibly: In linear time nothing is ever the same as it was. In cyclical time events repeat themselves in periods or cycles, moving with the slowness of tidal waves or with the high frequencies that determine the colours of light. One of the sources of popular music, that has a tendency to repeat itself, is the human penchant for rocking, swaying and moving in circles.
Time is change against a cyclical background: when nothing changes and the usual cycles repeat themselves we say that time is standing still. Time is the sovereign measure to which living nature stirs. Many facets of life are modulated by the passage of time: the clocks of crabs are set by the periodicity of the tide, virus and bacteria have their incubation time, trees produce bloom and fruits in a seasonal sequence, there is a meaningful message in the light pulses of fire-flies, the sounds in voice and speech utterances, the harmonic relations in music.
Straight time and cyclic time are important in communication. We will call the information exchange with and within the human organism external and internal communication. Internal communication plays a vital role in the healthy functioning of organs. It is taken for granted until the stomach is upset or the heart skips a beat. Efficient movement, as in athletics, in individual and team sports is obtained by coordinating internal functions and external behaviour.
Cyclic time is characteristic for many coded messages. These messages, also called stimuli, sometimes interact with singular events in straight time: time-slots that offer an exclusive opportunity, e.g. a phase of fecundity, or the sensitive period in which a child can acquire the use of language, or the phase during the day or night that a medical drug has an optimal effect.
To understand the role of temporal-dynamic qualities in internal and external communication, we will become familiar with time and time-scales. Like music, nature performs in various measures: presto for humming birds, andante for humans, largo for turtles.
"The whole episode of human presence on this earth is a mere speck in the history of the universe".
This reflection on time is from Stephen Jay Gould, the palaeontologist. When he makes his comment (in response to a remark overstating the importance of man for the future of our planet) the accompanying shrug of his shoulders puts the activities of man in a different perspective. However, is it the proper perspective? You might say with equal right that the history and the future of the universe do not concern us, and that the proper perspective for humans is the history of humanity, man's individual life span in particular, and last but not least mankind's immediate and distant future.
We have a rational idea of cosmological time, and it has no connection with time as experienced in human life: the cosmos is simply too large to arouse a sense of space or time in proportion to its size. When we talk about the origin of the universe or the life-cycle of stars, we shrink our time-scale. We enlarge it when we discuss a quantum experiment on elementary particles. We stretch and compress time until the duration fits the capacity of our imagination. Personally I feel comfortable with the view that time has no beginning and no end but can be episodically stretched and compressed (J.S.Stamps 1979). This has for consequence that in my spatial perception there is room for the infinitely small as well as for the infinitely large, thanks to relativity and the elasticity of time. While some parts of the universe disappear into nothingness, others are recreated and begin a new existence. Time is stretched along with the expanding space: when objects in space become unimaginably large and distant, they move at speeds that are equally beyond our powers of imagination.
Events in an environment of cosmic size can be taken in by our imagination, but only if we drastically reduce the spatial dimensions as well as the time-scale. The light year as a unit of distance is a reduction device, that helps us to handle the unimaginable. The Planetarium, an auditorium-sized model of the universe, is helpful and so is the book and video by Boeke/Morrison/Eames: 'Powers of Ten; the world in twenty steps'. Even more helpful is a piece of the magic mushroom, like the one which is nibbled by Alice in Wonderland whenever she wants to fit into a new environment. By stretching and shrinking space and time we obtain access to the micro- and mega-worlds. Micro-telescopy has enabled us to see similarities that would otherwise have escaped our attention. As we let our thoughts fly through space and time, we constantly change frames.
In the world of molecules and atoms, we help our imagination by multiplying the dimensions and stretching the time. Looking over the shoulder of Dr J.P.Tollenaere, professor in computational chemistry, I see how he simulates a chemical reaction: the screen of the computer shows a macro-molecule the size of a football, slowly changing its configuration. Bonds between atoms are rearranged under the influence of electrical and Van der Waals forces when a receptor site on the molecule is approached by a molecule with properties of affinity. The events on the screen are the result of calculations of the intra molecular forces of attraction and how they affect each other. We see in seconds what in the real chemical reaction occurs in nanoseconds.
The beginning of the universe was the
beginning of time. With an explosion of energy, the 'big bang', the forces of nature, gravity and
the other attracting forces, came into existence. They gave birth to the smallest particles of
matter, which eventually combined to form protons and neutrons. It was the start of physical
evolution: the successive formation of atomic nuclei and chemical elements.
According to superstring theory the elementary particles can be described as vibrating strings of linear dimension. As in this quote from Encyclopedia Britannica: "The basic entities in superstring theory are one-dimensional massless strings only 10-33 cm long. ....The strings vibrate, and each different mode of vibration corresponds to a different particle. The strings can interact in ways that correspond to the observed interactions of particles. "
Since we know that particular patterns of oscillation are the objects of selection in building well functioning networks, it seems that at the level of elementary particles this is also the case. Oscillating strings or loops are subject to selection in the process of building protons neutrons and atoms. E.Rubenstein has pointed out the analogies between various stages of nature's evolution on the planet earth. The three stages are: physical, biological and cultural evolution. "What nature does, in essence, is to make assemblies. Simple constituents agglomerate to more complex compounds". Nature has used one and the same logic for constructing
The principles of evolution of life on earth, as discovered by C. Darwin and A.R.Wallace, equally apply in other time-scales:
The general principle of 'variation + selection', the creative logic of nature, is found in all time-scales. It implies that
|STAGE OF EVOLUTION||INFORMATION-CARRIER||MESSENGERS|
|biological||DNA in nucleus of cell||RNA molecules|
|cultural||language, documents||lore, literature and law|
Map 4.3.1 Consecutive phases in evolution and the messengers transmitting the information from the genetic memory to the construction site.
Physical evolution. According to E.Rubenstein evolution creates a continuing sequence of assemblies. The first assemblies are created in the hot stars, they are the elements of physics and chemistry. When new elements are generated, chance associations of particles give rise to various atomic structures. Their survival depends on whether or not they are supported and reinforced by their environment. If they are rejected they will be replaced by different structures which may undergo the same fate. Or, if the environment is favourable at the moment they come into being, they will continue to exist. By then their internal structure contains the information of how to construct a viable element. Carrying this information, from the nucleus outwards, are subatomic intermediary particles, belonging to the class of bosons. They act as messengers and direct the agglomeration of other particles into a similar structure as the one from which they originate. There may be variations between one generation and the next, and if a variant is particularly well accepted by the environment of that moment, an element with new properties has been created.
In biologic evolution the results of previous successful developmental steps are laid down in the internal structure of the members of the species. The blueprint for every new individual is stored as a summary report of its creation and development in the past. This blueprint is written in the form of DNA, a macromolecule that holds the archive of its evolution in abbreviated form and acts as a phylogenetic memory. DNA is a long thread-like molecule: a twisted spiral ladder on the surface of which the genetic information is encoded. It is a major component of the nucleus of cells. The DNA molecule generates replica's of itself and sends out directions for constructing a new individual. The score-book with instructions for rebuilding hereditary form and function is called the genome. By incidental errors in copying, some copies deviate slightly from the original. These are called mutants. The offspring with the variation may be more or may be less viable than the original. That depends on the demands of the environment. In a changing environment mutations make it possible to adapt to the new demands. Of one generation those variants with the best fitness survive. They are selected by the environment and have the opportunity to reproduce. The unfit die before they have reproduced. The living organism depends for its subsistence on its environment. A successful interaction of a species and its environment results, among other things, in the capacity to create the proper environment to which it has become adjusted during its own evolutionary creation. Thus the creature is created to be a creator.
The cell-nucleus that contains the genetic memory, sends out messenger molecules that deliver the information necessary to construct the protein molecules on which the organism's form, function and behaviour are based. The messenger (RNA) molecules direct the process in which particles from the environment are attracted and assembled.
A two-way information exchange between the species and its environment is the motor of evolution:
The two flows interact at every intersection of the network.
Selection is involved in evolution of species, in development from the egg (epigenesis), and in subsequent adaptive learning by the individual (9.5). In epigenesis, as in evolution, the environment shapes the course of development by interacting with the genome. The environment provides stimulating challenge: selective pressure gives rise to the adaptations that improve the resilience of the individual. An increase in fitness in the evolutionary sense is the unavoidable result of selection by the environment, not a purposeful activity on the part of the species. Selection occurs more by chance than by rule. The successive generations survive by trial and success. Epigenesis, the unfolding of the individual, has the semblance of being purposeful when seen from a distance, in "hindsight". In close proximity it is the outcome of variation and selection. We'll discuss later in what degree involuntary or voluntary processes are involved.
Cultural evolution is a further adaptive development by a group within a species. Evolution is the phylogenetic learning process of a species, as contrasted with ontogenetic learning in an individual of that species. Together they have resulted in the development of an intelligent mind in man and this has given rise to cultural evolution. Social institutions, arts and crafts, technology and science have developed in correlation with the human mind. The information contained in our cultural patrimonium is transmitted to new generations by imitation, education and training. Oral and written language is one of the messengers, supported by formula's, diagrams and images. Variations of ideas are being tried out and subjected to discussion before being carried out. Fitness, in the Darwinian sense, depends on convincing evidence and persuasive arguments. A rapidly changing social and cultural environment selects the whimsical values of the day. Fortunately seeds of cultural information can lie dormant to be rediscovered later and give birth to a renaissance.
All forms of evolution are creative and innovative, be it at the physical, the biological or the cultural level. When the universe was created chaos made place for material dimensions and time. Physical evolution has paved the way for chemical and biological evolution, and the human society has launched a powerful cultural evolution. Mental activity and information technology have recently started a new epoch of accelerated evolutionary design of future institutions and technologies (E.Rubenstein). Understanding the past and present of anthropogenesis is a sound basis for making the choices that will determine the future of human societies. In this book we take part in an adventurous walk through time:
Variation and selection in successive generations are the source of natural and cultural progression. At the cellular and molecular level generations succeed each other in a short time and adaptations occur rapidly; adaptive changes in species of more complexity take more time. An important and useful concept in this connection is response time: the time needed for a species or quasi-species to respond to a change in the environment (= a stimulus or challenge). It is an index of the time interval or the time window in which the evolutionary process takes place.
|the macro cosmos||life on the planet earth||the micro cosmos|
|aeons||years, days, seconds||nanoseconds|
Map 4.4.1 response times and rates of change
Since stretching and compressing time appear to be helpful in portraying reality (4.2), we will make use of 'time-scales', a series of magnifications with which we view our world, from the cosmos to the immeasurably small. It is similar to the Boeke/Eames procedure of "twenty steps", the difference being that the accent is now on time, not space, and the number of steps is limited. The tele-microscope acts as a time-lens and enables us to dilate and shrink space-time and thus to obtain a view of otherwise unaccessible phenomena in nature. An interval on the time-scale is called a window.
The three wide windows in Map 4.4.1 represent parts of the universe from a human point of view, from macro systems to microsystems. The three frames contain all other windows that represent periodic events: the pulsations of galaxies, the birth and death-cycle of stars, the movement of the planets within our own solar system, orbital rhythms (caused by planetary interactions) that give rise to periodic climatic changes on extensive parts of the earth, the seasonal and diurnal cycles on Earth, oscillations within cells and populations of cells, they all occur in their own time-frames.
Night and day, and the seasons, are environmental factors of great significance for most forms of life on earth, also for man. Sleep and wakefulness and metabolic adaptations to the seasons are examples of entrainment of our physiological rhythm to that of the cosmos. The middle window is the one with which we are most familiar: life on the planet earth. In the centre the 24 hour time-slot through which we look at events of daily life, with its rhythm of night and day. On the right side the 'fleeting moment' of short term memory with which we shift our attention from one moment to another. This is in the order of one second, the tempo of 'andante' in music, the pace of a man's purposeful stride and of a quiet heartbeat. We'll call the time period of one second our unit of experienced time.
The events in the central part of the time scale are the only ones which we experience directly. Those outside are known to us as a result of observation and reasoning, but not by immediate experience. They cannot have the character of an incident or event, because their periods of change are either too large or too small for us to observe. Too large: the solar system seems to us stable and constant because the duration of births and decays of the system are beyond our human experience. Too small for immediate observation: the atomic nucleus and its cloud of electrons are hidden from our view. We have however indirect evidence about their behaviour and we use the knowledge to understand physical properties and chemical reactions.
There are ways to come near to understanding the forces of the atomic world: by simulating the environment in which they operate in the human time-window our brain can 'handle' them. The simulated behaviour of a macro-molecule, as we have just watched it on the screen of a computer, is an example. As Root-Bernstein describes it: 'the act of understanding is not purely an intellectual experience but a sensual one as well'. And in the words of Polanyi: 'Understanding begins with ... the ability to mentally extend or project oneself into the object of study'. Watching the computer-screen you feel the forces of attraction at the atomic level. This sensual experience helps you to understand what is going on when a long protein molecule folds back on itself, or when receptors on lymphocytes make their contribution toward an effective immune defence. The same ability helps the physician in his diagnostic probing and tentative therapy. It is then called empathy.
|time constant||aeons||days minutes||seconds - 1/100 sec|
lymphoid slow, lymphoid fast
|neural slow, neural fast|
I think that you have been surprised, just as I was, by the discovery that form and function develop according to the same principles (3.1). Both are adaptations to a certain environment. They differ in that their positions on the time-scale are at opposite ends of a time-window: we observe form-adaptation (morphogenesis) by shrinking a long period of time, we observe function through a time-stretching device, and they are exactly the same.
This is J.Pringle's discovery: while studying the contractions of flight muscles in insects, his interest was aroused by a relatively autonomous oscillator that, interacting with structures evolved for the purpose of air-borne motion, served a vital function in an animal's life. He directed his attention to other oscillating systems and discovered that non-linear oscillations play a pivotal role in many life-processes, such as epigenesis (the activity of gene-expression during individual development), metabolism, and learning.
When I wrote to Dr Pringle in 1972 and showed my interest, he referred me to the work of Goodwin. This brings us back to our topic: time as an organizer of growth and development.
When Bryan Goodwin (1959, 1963) studied the temporal organisation of cells, he described three time-windows through which we can look at activities within and between cells:
|20 years||3 hrs -100 s||100 sec -||- .01 sec||nanosec.|
Map 4.4.3 Time windows through which to look at the human world
Every system has a reaction- (or response-) time that determines it's position on the time-scale. It is the time required for a system to respond to a stimulus or change in the environment The response times are different for the three systems. If we look at single cells, the values for the metabolic responses are between 0,1 sec and 100 sec. Adjoining values are seen in the epigenetic system (ontogenic development): 100 sec. to 3 hrs. Genetic fluctuations in a population of microorganisms in response to a stimulus (change in the environment) take days or weeks before they stabilize.
In a cell's metabolism oscillations can arise when e.g. two enzymes are coupled by a reciprocal feedback inhibition (the increase of the one inhibits the other). These are non-linear oscillations in the window of 0.1 to 100 seconds, and can show complicated types of interaction. One consequence of their interaction is that it gives rise to sub-harmonic phenomena, with periods of 5-30 min. or longer. Since this is well within the range of epigenetic processes, a metabolite which oscillates at such a low frequency can be a significant element in developmental processes. In this way rapid and slow systems are coupled to each other for a weak or strong interaction.
If a stimulus acting upon the cell is strong and prolonged there will be an initial rapid response by the metabolic system, followed by a slower response due to changes in macro molecular concentrations (macromolecules are proteins with a specific configuration at their surface that carry important "prescriptions" for development). This is a second level response which indicates that the parameters of the metabolic system are changing. Thus it must be regarded as a response by the epigenetic system of the cell. The epigenetic variables are the controlling parameters of the metabolic system, and actually define the steady state of the metabolic system. A higher order (epigenetic) process, of low oscillation frequency, sets the parameters for the lower order process, that has a higher frequency of oscillation.
The oscillatory cycles in living systems vary from milliseconds to months or longer. Networks of coupled oscillators are the skeletal frame of life.
In this way the system with the rapid response time will carry out the directions as prescribed by the slower moving system.
It is a two-way hierarchy:
The two streams of information interact whenever they meet each other. If they represent conflicting tendencies, the result of their transaction is reconciliation. Oscillations in living systems will not be suppressed, because they establish coupling or reconciliation between higher- and lower order control systems. We have seen the example of coupling between the metabolic and epigenetic systems in a developing organism. As a coupling device, oscillation has a vital role to fulfill.
Chemical oscillation can be generated in various ways. Two or more metabolic structures may be in competition for precursor substances or for substrates that they have in common. This is analogous to a predator-prey relationship (see below), which causes the population densities of both predator and prey animals to oscillate with a phase difference.
As Goodwin points out, we benefit from the directness of system theory. Since variables of a system of lower order (with a shorter response time) can be eliminated from the dynamic equation of higher order systems, the description of higher order systems need not be more complex than that of lower systems. The complexity of nature is less confounding in a systems approach. This is also true for the complexity of human behaviour, as will be explained in Chapters 7 and 8.
The transmission of information in a network of oscillating systems displays a curious biological counterpart to the wave/particle duality in physics (is a light-beam a series of corpuscles or an EM wave? ). A chemical signal propagated in a biological matrix, can be considered from a material viewpoint: a shift in the density of a population of cells (or molecules), or from a communication viewpoint as oscillations in a dynamic network. Both views are equally valid, although the one will be more suitable than the other depending on the specific purpose.
Communication = ferrying information. A sender, it can be a cell or a system or a person, usually gets a response from the receiver, which in turn prompts it to send the next message. In the life of a cell, a change in a physical or chemical variable counts as a stimulus. Any such change pulls along a train of effects, usually aimed at counteracting the change or at compensating for it. Change and counterchange establish a dynamic equilibrium: a pull in one direction is redressed by a push in the opposite direction. Thus any event in the environment may give rise to a series of fluctuations such as growth and decline in a population of molecules, cells or synapses. Put in another way: an oscillation of chemical and physical variables in it's state of balance, is temporarily changed when the system receives a signal or stimulus from outside.
On quite another level, that of human institutions, we recognise analogical events. If we look at the equilibrium between political parties, it is typically a fluctuating one. When the right wing has a majority and has been in control for some time, people tend to favour the left, and the government is changed. After a while a reaction sets in, and voters incline again to the right. These oscillations within parties and between parties stabilise the course of politics in the long run. When unpalatable opinions are suppressed by a powerful majority, this may seem to promote stability in the short term, but it may prove to provoke a revolutionary movement in the long term.
Nearly all components of nature are part of one or more cyclical processes, which means that they continuously receive signals from contingent components in their immediate environment. Meaningful information is transmitted from one system to another by oscillation. In this way interactions between tissue components are sustained. The frequency in which systems oscillate are an indication of their readiness for communication. Systems with more or less similar response times are in continuous interaction with each other. The oscillations are the very substance of coherence. Interactions between a large number of oscillating systems amount to a network. A stimulus imparted to one of the components spreads like a wave over the other parts of the network. This has been clarified in Chapter 3 by an example from embryogenesis.
When two or more non-linear oscillators interact by coupling, the phenomenon of sub-harmonic resonance (or frequency division) may occur. In this way a periodicity of great regularity can be obtained that has a larger amplitude than that of the primary oscillators. Circadian clock mechanisms of many different species of organism are "synthesized" from oscillations with a period considerably less than 24 hours. In Goodwin's experiments fluctuations with periods of 1-4 hrs were measured in concentrations of a radioactive labelled amino-acid in chick embryo's. Large populations of cells remain in synchrony with each other, even a whole group of embryo's is in synchrony. Such findings help to understand the temporal organisation in the developing embryo.
A cell is a living system and is composed of many interacting non-linear oscillators. These act as if they were themselves evolving populations. We also encounter evolving populations of oscillators in multicellular systems:
Development in these systems is engendered by the Darwinian principles of competition and selection. What exactly will be selected may be undecided. It is probably not one particular 'species' (or one or more of it's features), because it's fate is too closely coupled to it's immediate environment to be distinguished from it. We are tempted to believe that the target of selection is an oscillatory pattern that promotes resiliency within the system and so has survival value. Under the influence of random disturbances a population of interacting oscillators will evolve from states of less to states of greater complexity. The selecting principle works for maximum adaptive value. Evolution is always creative and innovative
We have had a look through our tele-microscope at various windows in the evolutionary process, without having to strain our powers of imagination. By adopting the habit of switching between adjacent windows, we have seen similarities that would otherwise have escaped our notice. Oscillations, coupling, and layered networks are not metaphors, created by an imaginative mind, they actually exist. Since Goodwin has demonstrated them in his chicken embryo experiments other researchers have given evidence, as a perusal of a review volume by Gray and Scott (1990) will show. The fact that more than a few students will have difficulty in understanding the reports, should not be a reason to mistrust the validity of the concept of coupled oscillations. It should rather be an exhortation to look for more examples in one's own area of expertise e.g.
The importance of temporal dynamics lies not only in the number of practical applications, but even more in the conceptual homogeneity of theoretical approaches in various disciplines.
Seeds of cultural information can lie dormant for a long time before being rediscovered
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