Natural Systems Theory

by Hugh M. Lewis

http://www.lewismicropublishing.com/

Chapter Eighteen

Extraterrestrial Biotic Systems

The general question and problems of extraterrestrial biotic or living systems concerns two sets of problems that are ultimately interconnected. The first problem is that of exobiology or of the search and discovery of living systems beyond earth and not autochthonous to earth. This includes the problem of the search for alternative "Goldilocks zones" or that range of metabiotic conditions that might be suitable for the sui generis development of extraterrestrial living systems.

The second problem is that of the extension of living systems and their metabiotic frameworks, beyond the boundaries of the earth's biosphere and ecosphere. This includes the transport and travel of human's into space, especially upon a long term and sustained basis, but involves further the challenge of developing self-sustaining biotic systems extraterrestrially, especially in sophisticated ways involving entire trophic systems and cycles and including a large diversity of species.

Models for the colonization and "greening" of Mars or other non-earth platforms have been thus entertained as possible scenarios of this kind of development. We look for potential Goldilocks Zones both for the potential of autochthonous life and for the potential of biospheric colonization. Whatever models or realities might emerge, the critical thing remains the ability to reproduce entire living systems in a manner completely independent of the earth's biosphere.

The two problems are convergent in the sense that our greatest likelihood of discovering life extraterrestrially, and of being able to examine and analyze this life up close, will be under the condition that we achieve long distance travel and colonization of space. The more we colonize space, the greater will become the likelihood of discovering extraterrestrial life. On the other hand, if and when extraterrestrial life is discovered, it is clear that this discovery will greatly galvanize our efforts towards colonization of space, and will probably contribute constructive knowledge of the possible solutions to such a challenge.

The problem of exobiology, or what is referred to as astrobiology, becomes from the systems standpoint the problem of extraterrestrial biocosmics. This is not the same problem of the search or presence of extraterrestrial intelligence with plausibly some form of technological civilization, though the latter problem implies the former. Presumably, if evidence of extraterrestrial intelligence were discovered, if contact were made, then the assumption of the Mediocrity principle, of the common place presence of living systems throughout the galaxy and the universe, would probably be confirmed.

At this point in our own technological development, which is the more likely discovery, of confirmatory evidence of alien intelligence or of alien forms of living system, no matter how primitive, remains uncertain. The discovery and refinement of our search for exo-planets beyond our Solar system increases dramatically the likelihood of at least discovering an earth-like planet in the habitability zone of its own star. But we do not know the range or possible variety of plausible Goldilocks zones in the universe, or the range of alternative conditions under which living systems may stochastically self-organize, or even the kinds or ranges of conditions under which living systems might thus become organized as a matter of course or chance.

Certainly, the quest for life, any life, beyond the boundaries of earth is a great motivator that drives the exploration of other planets, moons and our Solar system as a whole. We know neither the full range of conditions under which living systems may take hold, nor do we know completely the possible range or kinds of living system that may take root autochthonously under varying conditions. We do not even know exactly the kinds of conditions under which living systems upon earth first occurred. What we do know is that this did happen, and that it has resulted in the evolution of life as it occurs today on earth, including the development of intelligent civilization, or what can be called now anthropological systems of natural stratification.

The chance discovery of extraterrestrial life, even without the range of our own solar system, would be a revolutionary event in the biological sciences that would lead to a profound paradigm shift in our understanding and interpretation of life. This would especially be the case if the life were close enough to be within our grasp to study and analyze in a manner that would allow us to make accurate comparative assessments.

We are reaching out further and further into space, with space-based telescopes, and with new techniques for observing the stars and detecting slight variations in the pattern of light we receive from so far away. By far, one of the biggest motivators for our exploration of planets like Mars or the Moons of Jupiter or Saturn is the possibility of the discovery of either the conditions for life, or evidence of life itself, however primitive or exotic it may prove to be.

The discovery of new exo-planets, some relatively close by, others over a thousand light-years distant, during the last decade and a half, has galvanized this scientific curiosity in the possibility of the discovery of extraterrestrial life. We are learning that Solar Systems, many perhaps not unlike our own, are probably more common and prevalent in our Milky Way Galaxy, and probaby then in other Galaxies, than we were willing to admit before these discoveries. And we are discovering even in our own Solar System new planetoids and new complexities of systems and objects that again lend solid credence to the idea that life may not be that uncommon afterall in the larger Universe--that it may in fact "happen" whereever conditions for its occurrence make it possible. We know that complex carbon compounds and even amino acid structures are not uncommon on comets and meteoroids, and we know that these objects travel vast distances through the cosmos.

The search and discovery of exo-planets, and the increasing realization that star systems with planets are probably common rather than unusual, has galvanized the quest for extraterrestrial life forms, but this has only been one of several lines of inquiry that have converged in this quest:

1. Discovery of explanets with the necessary "earthlike" conditions as candidates for living systems nurseries.

2. Discovery and examination of extremophiles and unusual biotic conditions on earth where exotic life forms have adaptive and survived, sometimes for millions of years.

3. Discovery of possible or plausible "Goldilocks Zones" within our own solar system, either on Mars or on the satellites around the Gas Giants.

4. Discovery of astropaleontological evidence for past life forms, either in meteoroids, asteroids, comets, moons or planets in or beyond the solar system.

5. Discovery of extra-terrestrial organic compounds, organic chemistry and water in the universe, through astrogeology and geochemistry.

6. Discovery of extraterrestrial intelligence, primarily via radio astronomy, but also by other means, evidence of which would substantiate the independent origin of extraterrestrial biotic systems.

Hence it is with this kind of excitement and anticipation of new discovery that we are relatively rapidly reaching out to the stars in search of life, and that this quest will probably not go long unrewarded. The concept therefore of extraterrestrial biotic systems is no longer so strange or far-fetched, more the realm of science fiction than solid science, than it was half a century ago. We must give therefore the possibility of extraterrestrial living systems a fair hearing as possible, indeed, as possibly probable systems, that we must soon learn to deal with.

It would not be surprising in fact to find some form of living systems not to be rare in our Universe, but in fact quite common. General system theory almost predicts this likelihood, given the concept of self-organization of systems. There is no reason to expect otherwise. We are of course almost undone by the vast distances and depth of space-time that is involved in either communication or transportation with the distant stars. This would be a kind of dilemma, the relative isolation of space-ship earth, and of all stellar space-ships, not uncommon to all life forms whereever it may be yet found or thought to exist. The laws of physics that keep our feet firmly to the earth and that prevent our ships from traveling faster or even as fast as the speed of light are the self-same sets of laws that would apply to our would-be alien neighbors. An alien civilization on the other side of our Galaxy could have been broadcasting in our direction a signal strong enough to carry a message of their civilization to us for the last 10 million years, and this signal would still not have reached our listening radar ears. And we have been listening for a shorter time than we ourselves have been broadcasting, scarcely a century, which by Galactic standards is but an instant in Cosmic Time.

The discovery of extraterrestrial life would dramatically transform our knowledge and understanding of living systems, expanding our knowledge base by a order of magnitude, and providing an external source of information by which to develop the study of life on a more comprehensive and comparative manner. The discovery of each new independent form of life would have a similar consequence and allow our current paradigms to expand and shift to greater proportions than has already been achieved merely by the analysis of life on earth.

Whatever life we have yet to discover in the universe, beyond our earth, before we destroy ourselves in the process, must at least follow certain basic systems-based parameters. We might expect, for instance, some kind of cellular organization at about the same size as we find it on earth. Whether the genetic structure is exactly like our DNA/RNA helices, we might only guess, but we might assume that the informational content that allows self-replication to be very similar in many ways. The forms of energy it might depend on might be many and myriad--any kind of energy is potentially life-energy. Presumably, organisms on earth for the first billion years did not have the capacity to utilize the suns energy, and therefore probably depended upon some form of chemosynthesis. So chemosynthetic microorganisms, or larger, would not be unexpected.

Visible sunlight is of course a vast energy resource for life on earth, in its veritable green zone, to come to depend upon and utilize, but it would not be surprising if living systems elsewhere depended upon other bands of the electromagnetic spectrum than visibile light, possibly ultraviolet light or infrared energy. What if organisms elsewhere than earth came to depend upon nuclear energy as a source of energy, or the continuous pressure of gravity, for their living. Surprising perhaps, but not necessarily unexpected.

Two kinds of problems confront us in dealing with the problem of extraterrestrial living systems. The first kind of problem is the search for the autochthonous conditions of sui-generis, self-organized living systems somewhere in space beyond the earth that was not transplanted there from either the earth or somewhere else. This kind of problem remains largely hypothetical, though as we investigate living systems in extreme zones on earth, in submarine vents, under ice-caps, in isolated caves, in rainless deserts or in geo-thermal geyser pools, we discover the ranges and capacities, the possible tolerance limits and extreme adapations living systems, particularly uni-cellular systems, might possibly achieve, providing some confidence for a early chance discovery on a moon of Saturn or even beneath the surface of Mars.

This problem relates directly to the search for geophysical systems and possible contexts that might offer or at one point in the natural past, have offered the conditions ripe and ready for the spontaneous self-organization of primitive living systems. Presumably, water is a key compound, and fortunately, it appears to be commonplace if not always abundant outside the earth in the larger Solar System. We search for viable energy sources, presumably heat or chemosynthetic if not solar. We search for the necessary mix of possible compounds, presence of organics, presence or absence of complex or simple carbon compounds and minerals and gases that we know might be involved in the organization of life upon some level, at some stage, in its earliest development.

We also search for direct traces left by living systems, assuming they are there and abundant enough to leave signatures upon their world. We might look for green water or red, or an atmosphere rich in oxygen or evidence of erosion and sedimentation. We might search for evidence of soil deposition and weather that would suggest some kind of recycling system of basic nutrients.

            The second kind of problem, of terrestrial biospherics, is basically the problem of the extension of terrestrial living systems, or earth bound life-forms, beyond the earth,to transplant living systems to extra-terrestrial contexts. This is a problem that has confronted us from the very beginning of our space-programs when the challenge of life-support systems and long term survival in space became a crux to the problem of direct exploration. Surely, robotics and artificial intelligence has obviated the problems connected to life-support, but they provide even in the best of circumstances only partial solutions to a much larger problem of exploration and discovery.

            The problem of life-support for transplanted systems in exterrestrial contexts reaches to the problem of biospherics, or the problem of setting up and maintaining totally isolated systems of living systems that are self-maintaining and relatively complex, for the long run, in cyto or biotronic, artificial environments. So far, the problem of sustainability and diversity of biospheric experiments in earthbound settings has had a mixed track record. It is relatively easy to maintain fairly simple Winogradsky columns or terrareums on a long term, perennial basis: it has proven extremly difficult to create a truly diverse ecosystem with multicellular life forms that would replicate trophic structures on earth in artificial environmental conditions, especially in long-term, self-maintaining contexts.

            Both sets of problems, at this stage in the game, have less to do with the creation or direct discovery of actual systems of living organism, as they have to do with figuring out, finding or inventing the correct metasystems contexts that would prove viable for the existence of extraterrestrial living systems, especially over the long term and with as few tethers to earth as possible. In other words, it has to do with creating or discovering correct environmental systems and contexts, and the possible ranges of these kinds of systems, that can possibly sustain life outside of the earth's own natural biosphere.

            In the colonization of space with living systems, there are a number of problems that would have to be effectively resolved. What is desired would be the creation of a self-sustaining metasystem context that would permit living systems to grow and reproduce over the long run. Many things would have to happen. A hydrological cycle, a nutrient cycle, a weather system, all would have to be effectively configured. A problem of food production, not just for humans, but for all living systems, must be solved. The problem of biomass and biodiversity would have to be accomplished, as well as a sense of self-sustaining ecosystems equilibrium such that the interior environments in space would not suffer degradation or circumscription over the long run. Systems that would be potentially evolutionary in the long run would have to be established, and this would entail some game plan of interconnectivity between colony out-stations. In other words, no station could be effectively isolated in the long run without some degree of interchange and exchange with other systems.

Biospherics of Extraterrestrial Organic Metasystems

The challenge of locating possible goldilocks zones beyond earth is related to the problem of creating habitable and self-sustaining metasystems beyond the earth's biosphere.

Learning to design and maintain biospheric metasystems extraterrestrially would force us toward a more detailed and integrated understanding of how biospheric systems operate, both on earth, and potentially, beyond.

Besides comprehending more realistically the functioning of terrestrial biospherics, there are other challenges that would also have to be met on some scale. Presumably, artificial biospheric and biotronic metasystems can be constructed and developed on earth to some degree.

These kinds experiments have already been begun on earth and move forward on different scales. There seems a critical need though for a larger and more concerted research effort in this direction, as the possibilities have not even been scratched, much less exhausted.

What would be sought are the optimal kinds of designs and design constraints for a range of different kinds of biospheric systems. Such biospheric systems could potentially be linked in space, and if modular in design, gradually extended to larger and more complex systems, encompassing a broad number of experiments with different forms and combinations of flora and fauna.

The systems constructed and developed in space would be entirely artificial in design, and thus, on a basic level, entirely open to alternative systems development and the potential for human creativity and serendipidous discovery and invention.

Such systems, in order to make them work, would begin on a relatively small and simple scale, and be graduated up to larger and more complex designs by a series of stages.

Construction in zero-gravity conditions in space might potentially lead to the design development of very large structures that might provide sufficient area and interior space to permit fairly complex and high bio-mass experiments to be conducted.

There would need to be developed some efficient and cost effective system of transportation that would enable us to lift into space large bulk quantitites like water, soil, rock, and construction materials needed for building such biospheres.

It is clear that, for terrestrial living systems, water is a main component and must be transported into space, gathered in space, or created their by some means. This would entail containing in a relatively large quantity of water. This water would furthermore have to be cycled continuously. At this stage, we are possibly talking of a kind of aquarium in which water can be maintained in a zero-gravity environment.

The quality of the sunlight would have to be such that it did not damage the plants that might be grown in space. Light would have to be filtered, and one can use either direct, filtered light energy from the sun, or indirect energy that is used to power green lights, or some combination of the two designs.

Such a space-system would resemble in many respects a kind of space-zoo, but might possibly include many mixed ecosystem habitats as well as more controlled environments.

Non-Native Extraterrestrial Living Systems

            Life on earth seems intimately connected with the covalent bonding properties and structures of a relative few elements called the period 2 non-metals of groups four, five and six, as well as the non-melts of period 3 groups five and six. The first set of molecules have the smallest atomic radii of all the elements, and the second set of period three have the smallest of their period and the smallest of all the others except first period and the halogens and noble elements. These elements have some of the highest ionization energies of all the elements of the peiordic table except for the noble gases and the halogens. These elements also have the highest electronegativities, the tendency for atoms to draw bonding electrons to itself in molecular formations, of all the elements except for the halogens, which leads to polar covalent bonding structures and the influence of hydrogen bonding on molecules. It is seen with the larger organic macro-molecules that this electronegativity plays a significant role in catalysis, in state switching and in maintaining complex equilibrium within cellular environments that are critical to cellular function.

            The importance of these elements, and their periodic properties, along with hydrogen , which shares as a period one element many of these properties, as well as a kind of ambivalent identity as either a metal and a non-metal, seems to be critical to the formation and function of organic molecules, especialy the convoluted and plastic folding structures of the larger macro-molecules upon which living systems fundamentally depend. Therefore, it can be assumed that life most likely to be encountered will have many of these same fundamental organic molecular patterns, and will largely be composed of similar kinds of molecular compounds made primarily of the first and second period non-metals excluding the halogens and noble gases.

            The relative low solubility in water is an important aspect of these molecular structures, because on earth, all living systems are associated with a life in water and of water. It makes sense therefore that molecules for living tissue would need to be fundamentally resistant to dissolution in water.

            Perhaps most importantly for this small group of non-metals, they have high oxidation states, the ability to donate electrons, and can form a range of oxidation states. This wide range of oxidation states and relatively high oxidation numbers that can be achieved, entails that these elements are involved in the formation of oxide-ions. Nitrogen compounds in particular form a range of compounds that have oxidation states running across the entire spectrum from high oxidizing agents to high reducing agents, and it is not surprising therefore that these same nitrogen compounds found in the amino acides and building blocks of proteins. Oxidation reactions generally yield energy as exo-thermic reactions, and this energy releasing aspect of these compounds becomes important in the organization of life and the transfer of energy required for this organization. The transfer of electrons and energy associated with this transfer is the main energy currency of almost all complex cellular reactions.

Covalently bonded molecultes from these elements tend to have relatively low solubility in water. They tend to have relatively low phase transition points, which means that they can change from a solid to a liquid to a gas over a relatively narrow range. They tend to be combustible with elements like oxygen, and to go into chemical reactions with relatively low thresholds of reaction. At the same time, some of these kinds of compounds form carbon-based chains or rings that can be extended and built to huge molecular structures, which tend to have certain plastic morphological properties.

It can be expected, therefore, from a systems standpoint, that most living systems encountered in the Universe would probably be associated with water as a basic medium, and with the main set of first and second period non-metals, excluding the halogens and noble gases, as the main backbone to its physical organization and construction. We would expect most living systems probably to be carbon based, and to be constituted by many of the same basic compounds that we find with living systems on earth. This is not to claim that non-carbon based life-forms wouldn't be possible or occur under different circumstances than are encountered on earth, and that other elements besides the life-elements might be involved in the core structures of compounds of living systems. It is to assert that the most likely and therefore highest expectation value, on average, would be carbon-based, water-fluid, and involving the key life-elements.

Biological Systems in Universal Perspective

To find what can be considered the universal in biological systems we must step backward and examine the basic structure of the organic molecules of the biological organisms we are most familiar with. To date, the only forms of life we know of are bound to our own earth. The question becomes, from a bio-cosmological point of view, not whether or not there are other living systems to be found scattered in deep space, but whether the systems that do exist would exhibit a similar kind of basic chemistry as the ones we know about here on earth The tetravalent structure of carbon compounds, combined with the high ionization energies of the carbon molecule, lend credence to the hypothesis that most life forms would be carbon based, presuming that the same periodic table of the elements can be found to replicated in a similar way on different solar-planetary systems harboring life. The manner in which these hydrocarbons are put together in different kinds of evolutionary systems of life may be substantially different, or lead to fundamentally different kinds of outcomes, but it is safely presumable that the fundamental molecular architecture would have a carbon skeleton.

Though we can assume that in all likelihood an alien form of life will have a carbon base, it also seems equally unlikely that the macro-molecular structure of these systems will be exactly or even very similar to our own life forms.

The most likely forms of life that we may discover, short of some form of alien intelligence that discovers us first, is likely to be rather simple and primitive forms of bacteria and possibly primitive viruses. We assume these will have a simple cellular structure as do monera on earth, containing a complex cell wall and a basic complement of necessary reproductive machinery for protein synthesis and genetic transmission of information.

We can assume that an alien system will be evolutionary in a manner similar to how life evolves on earth--that its genetic information and coding structure will allow some form of mutation and recombination to occur to permit developmental change and epigenetic exploration and adaptation. We can even assume emergence of some form of eco-trophic system diving producers, consumers and decomposers within a geophysical framework that permits efficient utilization of some kind of basic energy--presumably light energy

Significant and steady progress has been made in the biological sciences in detailed understanding the structures and patterns of life, especially upon a microscopic and bio-chemical level, and in the technological applications and extensions relating to this understanding. Less progress has been achieved upon a macrobiological and ecological scale, though yet significant and noteworthy. The principle concern of biological systems theory from a metascientific point of view is therefore an understanding of what can be called the metabiotic context in which life originated, including the conditions that promoted the stochastic formation of the first reproductive life forms, and the development and interaction of this context within an eco-evolutionary context. It is not that we do not understand a great deal about the metabiotics of living systems already, as we are clear upon the environmental requirements that such systems need in order to function and achieve their development and survival. What appears to be lacking in this regard can be called a central organizational theory, a grand synthesis, that comprehends all biological systems, at all levels and in every context of their articulation and occurrence, in a systematic and coordinate manner. Perhaps this is an impossible goal, given the inherent complexity and indeterminateness of all biological systems, especially upon a macroscopic level. But it is clear as well that life has achieved remarkable success upon earth as a result of its ability to maintain both an internal sense of organization through adaptation, and an external sense of order in relation to the metabiotic environment, and it is clear that without this effective kind of order life would have probably failed long ago.

Biological systems are complex molecular structures that are so arranged that they interact in a manner that permits: 1. Continuous growth and regeneration of the system derived from elements drawn for the immediate environment; 2. Reproductive modification and evolutionary differentiation of such systems such that in time, a single system, will become two or more separate systems; 3. A self-sustaining metabiotic equilibrium to be established between the system and its host environment.

Any system that meets these three criteria, more or less, can be categorized as a living biological system. The minimal form that such systems have taken on earth have been in viral and bacterial, or prokaryotic. These minimal forms of living system determine that something like a cell is the minimal constituent organization of living systems. But even viruses can be seen as essentially parasitic extra-cellular entities that depend nevertheless upon cell invasion and subsequent lyses for the fulfillment of basic living requirements. It follows that a pre-biotic system must have been a kind of pre-cellular system that nevertheless permitted the eventual development of simple cellular forms, and the movement from some kind of pre-cellular to fully cellular form must have entailed the bounding of nucleic acid chains constituting the RNA-DNA complement of a cell within the cytoplasm contained within a cell-wall, or glyocalyx, and the subsequent differentiation of internalized organelles or cellular substructures that enhanced the equilibrium and function of the cell.

The amazing feature of all biological systems on earth is their remarkable protein plasticity which is the product of the central dogma of earth-bound biology, the formation and conformation of complex protein structures from basic amino acids, and the metabolization of stored forms of chemical energy for the construction and function of these complex molecular structures. This basic protein plasticity translates into the adaptive functioning and formation of complex mechanisms of biological tissue, such as motors and sensory apparatus, that permits the multi-cellular organization of life to achieve new levels of integration of such systems. We cannot ignore this degree of plasticity of form and function in our consideration of the evolutionary development of complex metabiotic systems.

It follows that any biological system that occurs beyond terrestrial limits for earthbound biological systems must have minimally these basic adaptive traits, though the particulars of how they function and may be organized may vary considerably. I would predict that all or at least most biological systems discoverable in the universe would probably be carbon based, or what we could refer to as "organic" systems, and that these systems would probably utilize the elements of hydrogen, oxygen, and nitrogen in very similar ways as these processes occur in terrestrial biological systems. This has much to do with the electrostatic characteristics and hydrogen bond characteristics associated with combinations of these elements. It seems inconceivable to think of any living system, especially as a complex metabiotic system, outside of some source of water. Water has attributes that make it uniquely appropriate for biological systems. Water may have been a common byproduct of many early planetary formation processes, but the train of natural events that would permit its accumulation on a scale as found on earth, the watery planet, may be relatively unusual, and I would suggest, probably a necessary prerequisite for the formation of any living system. Large masses of water, as found in the oceans, permitted the cooling and stabilization of the temperature of the earth and a regulation of its climates. It would have permitted the kind of displacement of continental land forms and the drift we find as on the earth.

Early prebiotic conditions for life demanded the presence of large, stabilizing body of water and a hydrologic cycle. The atmosphere of the planet would not have been of the same composition as it is today, and may have passed through various phases of ammonia or carbon dioxide or sulfur dioxide compounds. The large abundance of silica in the earth's crust suggests that silica-carbon compounds containing sulfur, nitrogen, oxygen and hydrogen may have been precursor even to the formation of large quantities of water. One would expect both a very active volcanism, a thick condensed and turbulent atmosphere that may have been very active in creating lightening storms on a regular basis, and possibly a continuous round of meteorites and comets showering the surface from crowded night-time skies. Solar radiation, perhaps more intense in some wavelengths and particle emissions that it is even today, must have played a critical role in this early phase of proto-biotic development. Thus, the atmosphere could not have been completely cloud covered with gases, but partly clear. These basic conditions have been replicated in the laboratory and have demonstrate the formation of a range of organic compounds that would be considered prerequisite to the formation of biological life-forms. Life on earth probably originated during one single period of time when the general conditions became most suitable for this kind of development to occur. The life that formed at this time was capable of surviving and proliferating in the world, via the waterways that were then established, and then became capable of rapidly adapting itself to a wide range of environments and changing climactic conditions. Eventually, the biosphere took shape and complexity to the point that itself produced a stabilizing influence on the bio-geophysical framework that supported life in the first-place, with the gradual emergence of oxygen in the atmosphere and the formation of an ozone layer sufficient enough to protect living systems that emerged from the water onto land. Photosynthesis by algae was an early adaptation, and this photosynthesis fueled the biosphere.

The object of biological systems theory therefore becomes the understanding of this sense of inherent, systematic order of living systems relating to their adaptive equilibrium and capacity to change rapidly to meet changing circumstances. We should expect, furthermore, that all living systems, whether terrestrial and earthbound, or hypothetically extraterrestrial and alien, must achieve a similar kind of systematic success in their adaptive organization if they are to survive and develop evolutionarily. From this we may state some initial propositions:

1. Living systems tend naturally toward evolutionary differentiation in order to achieve adaptive success to changing environments.

2. Living systems depend upon the interaction and maintenance of an effective meta-biotic context for their adaptive survival and reproductive success.

3. The metabiotic context for all living systems consists of a bio-geophysical substrate that is critically conditioned by co-evolutionary and eco-evolutionary relationships between differentiated organisms. Many of the changes that occur in this context are the consequence of the evolutionary differentiation of organisms

Therefore, it follows that the evolutionary differentiation of any living population of similar organisms and the metabiotic context that conditions the survival and success of these organisms are not only interconnected, but inextricably bound together as a complicated and interdependent, or what can be called a complementary system of relations. To specify causal arrows or primary determinants of such a system is to beg the question of the hen or the egg.

Biological systems theory tends to be concerned with answer certain kinds of questions of the natural world. For instance, the explanation of the stochastic origin of living systems from pre-biotic inorganic conditions is important to understanding how living systems that subsequently formed were organized and articulated in a larger geophysical setting. The problem of the extinction of species, and especially of mass extinction episodes, becomes important to explain as a critical outcome of the formation of a climax ecology and the oversaturation of the system by certain central biota. Similar, the question of the sustaining meta-biotic context for the shaping of living systems and the articulation of these systems in larger ecological frameworks becomes important. The question of the likelihood and existence of extra-terrestrial biotic systems, and the necessary prerequisites and predictable structures for these systems becomes important to answer as well. Understanding living systems from a synergistic and holistic point of view requires that we understand the emergence of superorganic properties of living systems at different levels, and the coordination of biological systems upon multiple levels of integration.

If we understand evolutionary speciation as a form of meta-biotic differentiation of an organism through success generations, or regenerations, and we can understand that, at the level of the multi-cellular eukaryotic organism, such reproduction is primarily social and sexual, entailing the exchange of genetic information between different but similar organisms, then we have set up a dynamic of population differentiation and the occurrence of a macro-biotic patterning of differentiation that incorporates the individual as the member of a larger group. So strong and critical are the ties of the individual to the group, that loss of an effective group context spells almost invariably the death of the individual. The cooperative achievement of such reproductive populations represents both an advance and at times a disadvantageous constraint over reproductive and adaptive possibilities of organisms, and is similar to the revolutionary achievement of multi-cellular organisms over singe-celled organisms. Individuals in groups yield something, but gain something back, and effectively interact and cooperate to create an entirely new level of metabiotic organization that did not previously exist before such social interaction took place. When we see extinctions upon the macrobiotic level, we are seeing the relationship and dependency of the individual organism upon the group in full swing--in fact, we see little significant evolutionary change nor significant extinction events associated with the speciation of prokaryotic and one-celled organisms. Group and social organization of living systems appears therefore to raise the stakes considerably of the evolutionary game--it involves both greater risks and greater rewards, and pushes the entire system to a new and higher level of organization and functioning.

Large groups as wholes are in the long run and in the large more resilient to normal and small fluctuations of meta-biotic pattern, but tend to be more susceptible to major changes and shifts of meta-biotic pattern, compared to individuals and less socially organized forms of life, that may be less flexible upon a local level of adaptation but demonstrate greater survivorship in times of greater environmental stress.

The natural tendency of groups is to expand beyond their adaptive limits, unless such expansion is counteracted by meta-biotic factors that serve to restrict or limit population growth. Therefore, in the evolutionary long run, it is likely that successful groups will expand beyond the carrying capacity of the larger region of their habitation, resulting either in the fragmentation of the population into sub-populations with a greater likelihood of competitive exclusion and phyletic differentiation of subgroups, or else the population as a whole must face the prospect of extinction.

The more dramatic and marked the environmental fluctuation, the more intense and extensive its effects, the greater the likelihood that populations, as coherent evolutionary species, will become doomed to rapid extinction. From the standpoint of meta-biotic systems, mass extinction events can only  be reasonably explained by high levels of over-saturation of regional ecosystems coupled with extreme and unusual environmental fluctuations.

So far, in the natural history of life on earth, no mass extinction event has represented a total extinction event, though it is not unreasonable to speculate that life itself may have had several fitful starts and stops in the early phases of its development. A total extinction event would entail the loss of all life on earth as we know it. This is not an impossibility, but its likelihood does not seem to be great, because of the achieved diversity of the total global ecosystem. The number of mass extinction events that have been recorded in the fossil record indicate that the earth's environment may have periodically undergone major shifts or  changes that affected the entire profile of life. It is probably impossible to say which of these major events was the greatest extinction event. It is probably also impossible to identify the total number of minor extinction events that have occurred in earth's biological history.

It is important to emphasize that from a meta-biotic standpoint, such extinction events are not primarily or exclusively explained by major environmental fluctuations alone. It is entirely possible that these fluctuations themselves may be in part due to the influence of living systems and their evolutionary trajectory, and that there may be inherent mechanisms of change and biotic reorganization of living systems which, under the correct conditions, can trigger extinction to occur upon a massive scale.

Understanding of extinction events is critical to a meta-biotic comprehension of living systems in a manner similar to how understanding and explaining cycles of economic depression are critical to the theoretical explanation of political-economic systems. This analogy is fitting because both cases are constrained and controlled at similar levels of complexity of interaction and relation that makes simple or straight-forward deterministic explanation impossible. The mechanism of mass extinction is diagnostic of the systemic relations of meta-biotic systems, and the explanation of these events can only be reasonably made at a meta-biotic level of understanding. Again, it is likely that unicellular organisms have remained for the most part resilient and largely immune to such large scale fluctuations of the meta-biotic system, though bacteria live and die daily in massive amounts. We can predict from such a general model that therefore the Giant Sequoias will eventually disappear from the earth, whether or not the hand of humans is involved in their destruction, and that the Giant Whales will also eventually pass in an evolutionary blink of an eye, while the organisms that thrive upon the decomposition of these giants will continue in a largely unaltered manner to feed upon their corpses. There is a critical meta-biotic reason for this difference, and this reason underlies the patterning of all forms of life as we know it.

The explanation of extinction therefore goes beyond conventional evolutionary theory that is focused upon speciation and implies extinction in the phrase "natural selection." At the same time, the understanding of the functioning and evolutionary development of metabiotic systems also comprehends more than merely the explanation of extinction from a theoretical point of view. If we see extinction events as expectable, if not predictable byproducts of larger cycles of development in natural, self-organized systems that tend toward complexity, then we can understand that a complete and comprehensive metabiotic understanding views extinction as but one possible outcome of many alternative pathways of development. It is an outcome, a consequence, of specific series of "events" that occur systematically throughout a large and complex system of biolotical relations, but it is never a fully determined outcome in the sense that other outcomes had some likelihood of occurrence. It is an outcome that eventually develops for all kinds of living organisms at all levels, but for a complex variety of different reasons, visits some kinds of organisms more frequently, or with greater likelihood, than other kinds of organisms. Hence, at this level, natural selection, especially as a form of extinction at the species level, can be said to be metabiotically governed by factors that may transcend and be beyond the control of the selection forces and adaptive capacities of any particular kind or coherent population of organisms.

Conventional evolutionary theory construes selection as primarily operating upon the individual, and altering the profile of the population gene pool as the result of differential selection, both in terms of adaptive survival and in terms of reproductive success. But this kind of natural selection invariably becomes mixed with another form of natural selection that operates in the background of all organisms lives. It is a form of selection that comes in a variety of ways and can operate upon a variety of levels at the same time--either through the physical environment or in terms of eco-evolutionary relationships or inter-specific relationships with other organisms. It is impossible therefore to tell where and when one kind of selection leaves off and another kind takes over. Certainly an organism that is weakened by hunger is more susceptible to disease and illness, and an ill organism would be less responsive to its environment and therefore more prone to predation, and an organism that is marginalized or ostracized from its group context would be more prone to hunger in the first place. Death by disease is a form of selection that often is beyond the adaptive capacity of organisms to control, and can sweep through and decimate the ranks of an entire population in very short order. It is unknown if entire species have been lost due only to disease, but this represents a kind of selection that is not clearly accounted for by conventional evolutionary models. Thus, natural selection as a process governing biological evolution must be understood in terms of the true complexity and systematic order that it represents and involves. At any given time, selective factors compose matrices and regimes of interacting determinants that influence the evolutionary outcomes for a population or for any individual of a population. These multiple factors operate in correlation to one another to influence the chances, or the stochastic outcomes, governing the survival of any organism or any group of organisms. It is therefore to be asked if natural selection doesn't always tend to favor the "fittest" or simply the "luckiest" and if the latter is the case, then it is true that evolution is completely blind. There is some partial measure of biological determinism involved in the evolutionary development and differentiation of species, and therefore the best answer is somewhere between the two--fitness and fortune both play an important part in defining evolutionary outcomes and success. This partial determinism is complex and of a complementary form. It therefore admits of no primary determinants or key causes, but only of a range of interacting variables.

For the most part, organisms also carry forward in an evolutionarily blind manner. They cannot predict the outcomes of what it is they do, nor do any organisms, even human beings, exhibit that much long range planning or sense of calculation of factors and conditions of their environment for adopting the best strategy. Therefore, selection that occurs usually occurs in spite of, or at least without reference to, the intentions or drives of the individual organism, though it invariably affects the options and outcomes governing these behaviors. Certainly, the better adapted the organism, the better that organism is capable of managing most events possible in the framework of that organisms life-world. Most organisms have evolved sophisticated if instinctual mechanisms of defense against predation for instance, particular predation by certain "known" forms of animals. The introduction of a foreign predator therefore, whose behavior is not in sync to an established metabiotic system of relations, may have a very destructive effect upon that system, as the organisms of such a system will suddenly encounter a new agency of their environment that they are without defenses or ill-equipped to deal with. Such an introduction of an alien species may have a consequence of selective disequilibrium to the preexisting system in a manner very similar to a sudden climatological fluctuation or change of availability of a limiting resource, for instance water.

The likelihood is great that any alien organism intelligent and advanced enough in its civilization to contact and visit the earth will almost invariably result in the destruction and displacement of humankind as the top-organism, and, unless such a species has an especially benign and pacifistic bent, might well result in the replacement of humankind. Such an organism may have biotic requirements similar enough to mammalian or animal forms of life that it might in fact be able to freely adapt to the earth's environment, excepting the great likelihood of infectious diseases that could possibly prevent and destroy such a species.

But this likelihood appears in fact to be quite remote--a greater likelihood is the earth being struck once again by a very large comet or asteroid. Contact with an intelligent life form in the universe will most likely be by indirect communication, receiving remote electromagnetic signals that exhibit regular artificial patterns. These signals may be so remote that they may have come from a civilization that was long since vanished from their planet.

BioCosmics, Exo-Biology & Exo-Ecology

            Biocosmics is the study of the possibilities of extraterrestrial living systems in the universe. We do not need to formulate a Life Principle of Cosmic Principle of living systems. The foundation of biocosmics as a legitimate problem of biology is rooted in the observation that on at least one planet, living systems are known to have developed stochastically and autochthonously. Then the question becomes, how common, how widespread, how variable, might living systems be in the larger scale of the universe. In other words, how rare, or how mediocre, must life be in the universe.

            From an informational perspective of functional thermodynamics, if each instance of independent living system in the universe, say the scale of our galaxy, is a living microstate, then what would be the biocosmic macrostate of life in the galaxy, especially from the standpoint of the stochastic self-organization of living systems. We cannot answer this question directly. Until we find evidence of other living systems that are extraterrestrial in the universe, we cannot get a clear idea of the larger picture of the macrostate of living systems in our galaxy. We know nothing of the norms nor the ranges of variability possible with living systems. We do know that living systems can emerge without the benefit of direct sunlight. We know they can emerge under physical conditions that would be considered toxic to most living systems as they occur on earth today, under relatively extreme circumstances, and possibly, this is how they may have originated upon earth as well.

            We might say that goldilocks zones are relative and relatively complex, and that optimal goldilocks zones would make the probability of living systems higher, and the probability as well that they are similar to our own in more dimensions greater. In other words, there is an average kind of optimal design pattern that living systems ought to tend to in the larger scale of the universe, and we can probably make some fairly good guestimates, like the basic non-metallic elements, that such systems should tend to.

            Development of photosynthesis would represent a saltational or revolutionary jump of living systems wherever they might occur. Presumably, it would not have to occur in the spectrum of visible light, though there may be reasons not yet well understood that would make the visible light spectrum optimal for living systems and photosynthetic pathways of energy production. If photosynthesis were to become important for the rise of stratified and highly differentiated living systems, as it apparently has been upon earth, then we would expect a condition of the goldilocks zone to be in a range not too close or too far from the main star or stars that define the solar system. Of course, if it were a binary or triple star system, then this would alter the pattern of the possible goldilocks zones for photosynthesizing organisms and systems.

            Most original energy pathways of living systems would be through chemosynthesis and presumably by means of some system of atmospheric exchange, possibly mediated by some form of vulcanism and even through patterns of frequent lightening strikes between the clouds and the ground. We cannot gainsay how advanced chemosynthetic systems might become, if such pathways were common and widespread and, from a systems standpoint, somehow renewable and therefore reliable in the long term. There are possibly other, non-photosynthetic pathways by which highly differentiated, multi-cellular organic systems might develop.

            The key here, from a systems standpoint, is that it has been an almost completely unexplored subject in the large and the long run. The range of variability is only as we know it on earth and as we are possibly learning about it within the framework of our own Solar system. The fact of the discovery of several hundred solar systems within a thousand lightyear radius of our own earth, and this being possibly the tip of the ice-berg in such a large observational radius, encompassing thousands of star systems and many candidates, tells us that this is only a nascent and embryonic field of inquiry.

Life beyond the earth, that has possibly formed in remote regions of the universe, is almost bound from the very beginning to have taken a different set of evolutionary pathways than that of the evolutionary history of life on earth. We might assume that the basic non-metals, oxygen, nitrogen, carbon, as well as the ambivalent hydrogen, that constitute most of organic molecules on earth upon which living systems are based, are the most likely candidate for living systems elsewhere and possibly everywhere, but this is not necessarily known. We cannot determine the macrostate of biocosmic systems on the basis of only one microstate that we are aware of--how similar or dissimilar exo-biotic systems must be to terrestrial systems is a problem we cannot answer definitively because we lack enough evidence one way or another.

            From an informational standpoint, living systems are almost by definition highly organized and relatively delicate as systems based upon complex bio-chemical equilibria, and yet we can bear witness to the resilience of living systems on earth. The amount of genetic information contained in even a single bacteria is relatively astronomical, much less the kind of information stored in a single eukaryotic cell. How complex living systems need to be to sustain such systems remains another unknown variable.

            In other words, living systems are information transmission systems. As such, they are highly organized and highly non-random, which makes the stochastic possibility of their chance occurrence relatively rare and infrequent. This alone would not make life in the universe prevalent or commonplace, but at the same time, we do not know the full range of possibilities of goldilocks zones that might be out there, which range is presumably vast on a cosmic scale.

            One fundamental question we can ask of living information systems as a function of their relative complexity. How simple can such systems be, and yet survive and differentiate to become adaptively robust? In other words, if biocosmic complexity has special significance for the prevalence or stochastic occurrence of living systems, then the simpler the system that is possible, the more likely its chance of occurrence. Assuming that most living systems would require some kind of structure similar to DNA-RNA chains, then some kind of DNA system based on three or even two rather than four alternative phosphate groups would be fundamentally simpler, and yet, would such system be sufficient or efficient enough. On the other hand, there would be no reason not to assume possible DNA structures based upon five, six, seven or more alternative phosphate groups.

            We might hypothesize, for instance, that simpler informational dynamics would possibly encode less information less efficiently, and the trade-off might be that such systems might be less adaptable to changing environmental conditions for survival. Such systems may rise and fall more rapidly than more complex systems. On the other hand, it could be argued in converse that more complex systems might arise under more complex circumstances which would entail a very narrowed range of survivorship under varying circumstances. Again, these are kinds of questions we simply cannot yet answer. We can speculate about the following hypothesis:

1. Simpler living informational systems should be statsitically more likely, hence, more common in occurrence, than more complex systems.

2. There is an optimal range of fundamental "simplexity"of living informational systems that would balance the trade-off between state-simplicity and systems adaptability to varying external conditions.

3. Most living systems that survive in the long run and in the large would tend to fall within this optimal range of "simplexity"

            We can posit a "dumbed down" Drake-Sagan equation for primitive living systems, by replacing the last three terms of the equation with an alternative term that would convert the frequency equation into a rate equation--asking a fundamental question, how frequently would living systems arise in our galaxy, and how stable might such systems become, once they have arisen.

N_eb/T_o= R_*f_pn_ef_l f_er

Where T_o equals the arbitrary frame of time at a presumed observational depth of space-time.

N_eb equals the estimated number of instances within a given frame of time within the Milky Way of living systems developing independently and stochastically as the consequence of autochthonous self-organization within some optimal range of goldilocks zones in stellar systems

R_* equals the average rate of star formation per year in the galaxy

f_p equals the fraction of the stars having planetary systems

n_e equals the average number of planets capable of supporting living systems

f_l the fraction of those planets that actually develop living systems

f_er with the final rate determining factor as the average rate of extinction/reproduction of living systems that do develop.

            Evidence of rates of star-formation and solar-systems seems to suggest that these numbers are actually relatively high, and we can assume that the number of solar systems having suitable planetary or lunar goldilocks zones might increase if we expand our range of the potential variabilities of such systems. We must at this time conclude that neither the Rare Earth hypothesis nor the Mediocrity hypothesis are probably correct, but that the final answer might exist somewhere in between the two, in what might be called the Medium-Rare Hypothesis. The final factor above f_l, would be a complex factor that was the critical rate determining factor for the rise and formation of such systems.

We must see the equation not as a fixed state equation, but as a kind of rate equation--in other words, living systems can be expected to self-organize and to possibly die out at a given frequency per area. If our search area encompasses a broad enough observational sphere of space-time depth, then we can assume that many living systems may have occurred over an extended period of time, even if current surviving systems are relatively few, and even in the context of our own solar system, as for instance upon Mars, or even possibly upon Venus, living systems may have once existed that did not survive in the long run.

Presumably, life upon earth has been continuous for something more than four billion years, and probably, as prebiotic systems, for even 4.5 to almost 5 billion years. This is a very long time, even on a cosmic scale. (If intelligent systems in the form of civilization only emerged in the last 4.5 million years, then we can estimate that the emergence of intelligent systems after the emergence of life on earth is something less than one to one thousand, and probably something more like .6 or .7 per one thousand.) The odds of finding equally long lived biocosmic systems is relatively small compared to the number of possible living systems that emerge and then become extinct due to changing environmental conditions. If for every one thousand goldilocks zones we find, life emerges once, and for every thousand times life emerges, one survives its intial protobiotic phases to become full blown biospheric systems, then we should estimate the likelihood of finding earth-like living systems extraterrestrially at something like one in a million, or a thousand thousands, for every solar system we discover, times the number of goldilocks zones that might exist or have existed for a given period of time.

The concept and periodic rate of goldilocks zones seem to become a critical rate determining factor in the emergence of survivorship of living systems in the structure of the large and the long run. Fortunately, it will probably become far easier to observe remotely the probable presence or absence of goldilocks zones in our neck of the Milky Way than the direct presence/absence of living systems themselves, particularly extinct fossil remains of such systems. The more we learn about possible goldilocks zones, either due to the observation of life under extreme conditions on earth, or the observation of the possibilities for living systems on moons or on Mars or whereever else we might think of, the better we will become at discovering the existence of such zones on distant exo-planets.

From the standpoint of the biocosmics of living systems, what we do not know is either the intrinsic variability of living systems (for instance, the relative complexity of the DNA code, and hence the molecular structure of such systems) nor the extrinsic variability (the range and factors of possible goldilocks zones suitable for the rise of living systems). High intrinsic and extrinsic variability might increase the prevalence of living systems occurring over time, while limited variaiblity in one or the other areas, or both together, would probably serve to decrease the odds of life being common place.

The question of the biocosmic patterning of life brings up another possibility, that of cosmic seeding of living systems from remote locations. Certainly, organic molecules can be carried from vast distances to strike suitable planets at the right time. The energy of impact of these transport systems could provide some of the conditions necessary for pre-biotic forms to emerge. Again, it is probably considerably less likely that entire living systems would be transported through outerspace from vast depths of space-time to seed and transplant living systems far afield. While remotely possible, it is unlikely that such systems could survive long periods of transport and the conditions of transport unless they were in a kind of dormant state. What we do know so far is that life on earth, though abundant in its own biosphere, and replete, remains relatively isolated in the vastness of a relatively empty space.

Surely, much credence might be given to some thing like the Zoo hypothesis. If highly advanced civilizations that are space-faring are proximate to our own solar system, they may have decided not to announce their presence to us at this time, for a number of reasons. One of the main reasons may be the risk of cross-contamination by alien systems through horizontal transmission of Non-native DNA structures. This could have catastrophic effect in both directions of contamination, and no intelligent civilization would run the risk of such consequences through intiating direct contact.

The case for the transfer of alien viruses, what might be called the Adromeda Hypothesis, that would be extremely lethal, might be a strong outcome of the direct contact with even primitive living systems, if it can be assumed that viruses or virus like agents of horizontal transmission are fairly common and arise early in the protobiosis of living systems. Under such a possibility, there would be strong motivation not to initiate direct contact with fundamentally alien forms of life at all. There is no reason to assume any level of compatibility for the mutual coexistence of alien systems of life. Such alien systems would become by definition competitive with one another and would be fundamentally inimical to proximate coexistence in their differences.

(If we are to extend this hypothesis to include the possibility of intelligent, space-faring alien civilizations, then we should not assume that direct contact would be necessarily benign nor non-competitive.)

The Essential Loneliness of Life

We may not be alone in the universe, probably we are not--in the bigger framework, we are most definitely not alone. But we are lonely in the sense that the distances are so great and our sense of isolation, of being alone, is very great. What evidence SETI has yielded after almost fifty years of continuous listening in on a large part of the heavens is that indeed we seem isolated, very isolated. This sense of isolation points on one hand to the preciousness of life in the universe, wherever it may occur, and gives warning to us of the possibility of its precariousness. The universe will continue unfolding in its own strange ways whether or not we are available to make our short-sighted observations.

We have one more grand hypothesis yet to consider, and this might be called the hypothesis of the Cosmic Filter. In a simple sense, we can say that life is rare enough in the cosmos that it is fundamentally, relatively isolated in space-time, and the distances and time-depths required to traverse this average gulf between living systems is so great that direct contact between contemporaneous living systems, especially those that are relatively remote, remains very highly unlikely.

However frequent or many living systems might be scattered about the galaxy and among all the galaxies, the average space-time depths between them essentially put most of the extant, contemporaneous biocosmic systems beyond the sphere of our observation, much less beyond the reach of our even more constrained systems of transportation. This essential filter of the vastness of space-time is intrinsic to the observational relativity based upon the speed-of-light. We cannot observe large sectors of the contemporaneous universe, even within our own galaxy, as the time it takes light from these distant sources to reach our telescopes is so great. We are in an observational hole in the universe, and we cannot see beyond its rim to observe what is going on in a contemporaneous sense in remote regions of the universe.

A civilization a thousand light-years away from earth would have to broadcast for a millenium in a deliberate manner, or at least wait that long after broadcasting, just to have the signal possibly be received by us, or otherwise would have to send out signals on pretty much a hit-or-miss basis over the entire cosmos, hoping to hear some kind of reply by chance. We are at just this stage ourselves. As the volume of space increases with the cube of the radius, the further out our signals reach, the vaster and vaster becomes the search area covered by these signals. As the signals fade out with the square root of distance of the signal, the signals that cover a vaster and vaster search space would be intrinsically much, much weaker, requiring very large arrays for reception.

There is no reason to see some of these hypotheses as mutually exclusive. A medium rare hypothesis would combine well with a Cosmic Filter hypothesis to effectively isolate most living systems from any form of contact between one another. We can assume that life has been fairly abundant throughout the entire Cosmos, and yet the distances involved would still be so great as to inhibit contact or communication between independnet living systems. Perchance that a very advanced space-faring civilization is in our neck of the Galactic woods, then a combined Andromeda-Zoo hypothesis could make them extremely reluctant to directly or even indirectly contact us if they believe there is little to be gained, but possibly much to be lost, by such contact.

The desire or need for establishing contact may be only a brief phase in the transition of a civilization to space-faring status, after which efforts at contact may give way to other priorities of exploration in the depths of interstellar space.

The likeihood of our remaining alone and relatively isolated for some time to come is great, but this probability should not necessarily impede our own progress towards becoming a space-faring civilization ourselves. Chances are probably significant that there are many examples of living system and even alien intelligence across the vastness of the cosmos--biocosmic systems are probably widespread and relatively common everywhere. But it is probably also equally likely that the average distances between these independent colonies of life are so great as to pose a fundamental obstacle to the capacity for contact or direct exploration. Chances are great that when we do find evidence of extraterrestrial living systems, they will probably be in the form of fossil evidence of pre or proto-biotic systems