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ISBN: 978-3-86888-135-6
"The electric light did not come from the continuous improvement of candles."
(Oren Haran)
"The purpose of evolution, believe it or not, is beauty and not fitness."
(Based on Joseph Brodsky)
At first sight the theory of evolution looks simple and clear. The trouble is, however, that the interpretation of how evolution exactly works is inevitably influenced by the prevailing zeitgeist: with Darwin in the Victorian era it was an authoritarian natural selection that rules mercilessly in a world of teeth, claws and blood, whereas in the modern age of globalization with its fierce economic competition, it is the blind belief in fitness as the driving force of evolution. Today however, it is high time to focus on the obvious fact that life needs sustainability and an ecological balance between growth and exhaustible resources. With this, the purpose of evolution becomes indeed beauty and not fitness.
This book is written for all readers interested in the evolution of life, and who are familiar with the main principles of modern biology. Contrary to most other books about evolution and life, it is focused on a specific subject, the complexity increase that has occurred during evolution. For this particular and essential aspect of life, the book provides a radically new way of thinking, why and how increasingly complex biological forms have evolved. On the following pages I will therefore introduce the corresponding new theory with the name Interaction Theory. A first, preliminary version of Interaction Theory was published in 2003 in German (Ruf M. 2003).
When it comes to the evolution of life, it is nowadays better to avoid any misunderstanding. I am not a creationist, nor do I sympathize with this movement. On the contrary, I believe in science and its way to approach the world. This includes my respect for Darwin's theory of evolution as an important scientific achievement. With regard to biological complexity however, I deeply believe that the existing evolutionary theory can only be part of the story. And the same can be said with regard to molecular biology, which offers impressive insights about the functioning of the cell, but does not add much to the question about complexity and life. It seems that something essential is missing in this regard. Overcoming this situation may require a new theoretical framework which builds on the established facts and knowledge, but puts them into a new context. As a result it can complement the existing evolutionary theory by clarifying why and how matter starts to organize itself into living beings of increasing complexity. An example for what I mean is classical physics and quantum physics. While the latter has offered the theoretical basis to describe matter on the atomic level, it has not replaced the laws of mechanical physics, which are still relevant to describe the behaviour of matter on the macroscopic level.
How is it possible to come to such a more comprehensive understanding of life? Personally I am convinced we are facing a purely conceptual problem. In other words, the unsatisfying understanding of biological complexity is not the consequence of still missing data or some decisive experiments which have not been made yet. It is rather necessary to think about a radically new approach, one which opens a new way to order and interpret the known facts. This is good news for somebody like me, who is not part of the scientific establishment. For a theoretical enterprise of this kind there is no need for a lab and research funds. All you have to do is to find a quiet place and start thinking how to explain the established facts in a radically new way. To be successful one needs enough time and freedom to think out of the box. In this regard it may even be an advantage not to be a part of the scientific establishment without any time pressure to publish or to seek funds. But what exactly can be expected as the result of such a theoretical exercise? In the best case it can detect a law-like process, which explains why and how life can emerge from 'dead' matter and become increasingly complex. And this is exactly what this book is about, the discovery of a law-like process of complexity increase as an essential part of the evolution of life.
At this point I want to address myself directly to you, dear reader. Obviously the following text demands your willingness and openness to look into a radically new approach quite different from the established theory. I am fully aware that this may not be easy, given the fact that today all theoretical thinking in biology is heavily focused on and around the concept of genes. But it is also clear that the development of a radically new approach can only happen by overcoming the established associations and beliefs. Therefore I want to ask you, please set your mind free for a different view on life and evolution. At the end you may then decide if the proposed theoretical framework contributes to a better understanding of the phenomenon life or not.
While starting to write this book, I became aware that the task has two different aspects. The first has to do with the presentation of the content, this in the sense of how exactly a new theory about complexity and life should be presented, so that the reader is able and willing to follow. Here I can only hope that I found a way of not being too theoretical and boring, but rather meaningful and inspiring. The second task has to do with the format of the book, this in the sense of in what detail the existing literature about the subject should be reviewed. When it comes to complexity and life the terrain to cover is huge, it stretches from chaos theory and thermodynamic, to evolution and ecology. To do justice to all these aspects is, I believe, very difficult if not impossible. Therefore I decided to avoid the risk of losing focus, and to concentrate on the essential. This means, I will only refer to publications that are directly relevant for my arguments. As a result some readers may find the text not detailed enough, while for others the contrary may be true. In any case, if I have not referred to the work or idea of somebody else who deserves to be mentioned, I would like to apologize in advance for it.
An unsolved puzzle of modern science is about life and its evolution towards increasing complexity (see e.g. Davies P. 1999 or Heylighen F. 1996). Life on earth emerged about 3 to 4 billion years ago, and there are many good reasons to believe that it started with relatively simple organic molecules forming some kind of chemical network (see e.g. Peretó J. 2005 or Shapiro R. 2007). In one way, until now not understood, certain of these molecules developed the ability to multiply and to pass this capacity on to the following generation (de Duve C. 1995). At this point a fascinating process called evolution was kicked off, which resulted in the emergence of structures of increasing complexity: the first molecules capable of reproducing teamed up with liposome-like structures and formed the first simple cells, which evolved over time into more advanced cells with outstanding biochemical power, the prokaryotes. Then bigger and structurally more complex cells, the eukaryotes, arrived on the scene, which organized themselves over time into first primitive organisms. Those continued the process of biological complexity increase by evolving into a generous biosphere with uncountable organisms, ranging from low to high complexity. And finally, not to forget about 200.000 years ago our own species Home sapiens appeared and opened a new, at first glance different chapter in the history of complexity increase, stretching from stone axe to aircraft carrier.
The whole process, from simple molecules to Homo sapiens, can be seen as a self-organization towards increasing complexity and provides the subject of this book: why and how is it possible that sterile, inorganic matter starts to organize into a manifold biological diversity including ourselves? Or in other words, this book deals with the cause and the mechanism for the self-organization of matter into living beings of increasing complexity.
Biological complexity increase demands an explanation
In the physics classes at school we learned that a system left on its own will inevitably go from a state of higher order to one of lesser order, or as expressed by the famous second law of thermodynamics: the entropy of a closed system will inevitably increase over time (see e.g. Schneider E.D. and Kay J.J. 1995). This law is exceptionally well confirmed and is in line with our daily experience, where things do not self-organize into a state of higher order. However, when it comes to the evolution of life, everything seems to go into the opposite direction. Even if we know that life is not violating thermodynamics, the self-organization towards forms of increasing complexity, and therefore higher order, is an astonishing and exceptional characteristic of life from the physical point of view (e.g. Davies P. 2003). Very surprisingly however, this subject is not very present in the life sciences. In modern textbooks about biology or biological evolution you may not even find the phenomenon of an emerging complexity mentioned, let alone a discussion of the question of how it fits our physical understanding. In order not to be misunderstood, it is not my intention to accuse biologists as a whole of ignorance in regard to this important aspect of life and evolution, which is clearly not the case. However, for me it is astonishing and sometimes frustrating to see the discrepancy between the relatively low attention given to the phenomenon by the mainstream in bioscience on the one hand and its fundamental importance on the other.
What are the reasons for this discrepancy? In my personal opinion the readiness to put the question of biological complexity not very high on the scientific agenda may have to do with the inevitable discussion about its implication. Here I mean that probably the first association coming to mind is that between complexity and progress. Does the emergence of biological complexity mean that evolution results in some kind of progress and is man the result of this development? By conviction, most scientists deny nowadays any special status of mankind in nature, and their answer with regard to progress is therefore no. However, can the conviction that scientifically all life forms have the same importance also mean that biological complexity is without any relevance? The answer is clearly no. It would be completely absurd to deny that evolution followed a trend from relatively simple structures, such as a bacterial cell, towards much more complex structures, such as an oak tree; or to deny the evidence that the complexity of ecosystems has increased during the course of evolution (see e.g. Heylighen F. 1996 or Kauffman S. 1995a). In the same sense it is simply a fact that humanity is very special and outstanding, compared to all other species produced by evolution. Both the obvious trend towards complexity and the emergence of an intelligent species like us demand an explanation. And as long as this explanation is missing, our understanding of life and evolution cannot be complete. And let's be clear, to accept that something qualitatively has happened during the course of evolution is not identical with the approach of seeing mankind as the only valuable crown of creation, as was the case in earlier times. Interestingly, when it comes to the history of civilization the concept of progress is much less taboo and nobody would hesitate to see the development from the Stone Age to Internet as progress. Be that as it may, I personally see it as a necessity to bring the complexity issue back into the centre of modern biology, where it deserves to be.
The meaning of biological complexity
For a discussion of biological complexity, it is obviously necessary to clarify at first what does 'something is complex' actually mean? In science, as in real life, the term complexity can have different meanings (Bennett C. H. 2003; Mitchell M. 2009). For example, the term complexity is used to name a field of study devoted to the process of self-organization, as well as in information technology as the measure of time and space used by an algorithm to solve a problem. When it comes to life and evolution the situation is even more unclear and no generally accepted definition exists (see e.g. in Gregersen N.H. 2003). It is obvious however, that the complexity of living forms shows certain specific characteristics. As an example, elephants and clouds are both complex structures. One fundamental difference between both is that all elephants share a complex form with the same structure, which is based on a common type of organization. On the other hand the clouds in the sky have a shape which is entirely arbitrary and does not show any organizational principles comparable to living forms (Haken H. 1994). This reflects the important aspect that organisms own an organized complexity in the sense that the components must cooperate and interact with each other in a highly specific manner to give the coherent unity. While this may also be true for dead objects, like a computer, the complexity of life has one very specific particularity. The self-organization of complex living forms, such as a human being, needs a very long time. An uninterrupted process of more than 3 billion years of evolution with uncountable reproduction steps was necessary. This means the self-organization of biological complexity is inseparably connected to deep time1. By combining this time dimension with the organizational aspect, it is possible to describe biological complexity in the following way: living forms show an organizational type of complexity, which can only emerge over geological periods of time (compare e.g. Bennet C.H. 2003).
Does this particularity indicate that biological complexity has a specific qualitative meaning? Up to now the answer is disputed and more a matter of personal interpretation and conviction (Davies P. 2003). The difficulties to associate any meaningful qualitative aspect with the complexity of organisms may be a consequence of the mentioned time aspect. We are used to seeing complexity connected with the individual organism. But this may not be enough, it may be necessary to consider the weight of geological time periods, in order to develop a better understanding of the possible meaning of complex life forms. As the reader will see, this is exactly what I will do in the following with the result that the complexity of life can indeed be linked to a very specific qualitative meaning.
What is life?
More than seventy years ago, Erwin Schrödinger, one of the leading physicists of the last century, wrote a famous little book with the title "What is Life?" (Schrödinger E. 1944). Schrödinger was struggling with the fundamental difference between living and dead objects. For him the mechanism of genetic heredity looked like the key to finding the answer he was looking for. Since then, knowledge about the molecular basis of life has dramatically increased, and the question about the mechanism of heredity and the molecular carrier of the genetic information has been solved. In addition, many other details about the molecular and biochemical basis of life were discovered at a breathtaking speed. A good example is the successful decoding of the complete genetic information of an increasing number of organisms, including humans. The result is an overwhelming amount of data, and one should expect that we are now in a much better position to answer Schrödinger's question "what is life?". However, despite the unquestionable successes in molecular biology, we still do not grasp what exactly separates a living organism from a lifeless physical object (Murphy M. P. & O'Neill L.A.J. 1995 or Stewart I. 1998 and 2003).
The problem becomes visible in the multiple efforts to come up with a definition of life. To give an example, the definition used by the American Space Agency NASA for the search for life on other planets is the following: "Life is a self-sustained chemical system capable of undergoing Darwinian evolution." Because the sun can also be seen as a "self-sustained chemical system", the decision as to whether something is alive or dead would be based on the criterion of whether it can undergo Darwinian evolution or not. As a consequence, this type of definition may help to decide if a respective system is alive by observing its behaviour over the course of many generations. However, it will not help to answer Schrödinger's question. To undergo a Darwinian type of evolution is without any doubt a central aspect of life, but to say life means it evolves is nothing more than to turn the problem upside down (Davies P. 1999). In this regard I fully agree with those who believe that this unsatisfying situation is purely the consequence of a conceptual problem and not the result of some still missing observational data (see e.g. Eldredge N. 1995, Gould S. J. 2002 or Rose S. 1997).
The problem of arriving at a more satisfactory definition of life may be closely linked to the question how and why biological complexity emerges. If this is true it may be necessary to understand the meaning of biological complexity first, before being able to answer the question "what is life?". And this is exactly what I will do in this book.
The two ways how biological complexity could emerge
Now, if the exact meaning of biological complexity is unclear, what can be said about its emergence? Here two fundamentally different positions are principally possible: the emergence of increasingly complex organisms during evolution may be either totally accidental or may be the outcome of a law-like process2 towards an increasing complexity (Davies P. 1998).
Obviously the consequences of both positions are very different. Let's start with the view that the increase of complexity during biological evolution is the result of a law-like process. In this case the emergence of increasingly complex biological forms would be the inevitable and logical result of this process. For such a process to take place, it is obviously necessary that the complexity of life has a particular, qualitative meaning. Otherwise, a law-like directionality towards progressively more complex forms is hardly thinkable. The process needs to build on a qualitative difference between different degrees of complexity. The probably most important consequence of this scenario would be the following. If we could 'rewind the tape on earth', or if the same type of evolution would happen elsewhere in the universe, it should follow the same route towards higher complexity. Thus, evolution would again produce a similar result, provided the overall conditions are the same and the law-like process has enough time. Obviously this does not mean that the result is exactly the same, but it should be similar (for arguments why a 'rewinding' would deliver a similar but not identical result see Conway Morris S. 2003). At the end, a law-like process of complexity increase during evolution would also support the assumption that if life has emerged also on other planets, then we are very probably not the only intelligent beings in the universe.
The alternative and opposite point of view is that of complexity as a purely accidental by-product of evolution. Here complex living forms would emerge merely by chance and not via a law-like process. This interpretation is favoured by evolutionary orthodoxy, which sees all living forms exclusively as the result of a gradual adaptation to the environment, driven by nothing else than selection on fitness. The mechanism on which this belief is based is the following (see e.g. Davies P. 2003 or Gould S. J. 2002): starting with a certain type of structure, natural selection acts at random in the sense that it can in principle produce lesser or more complex variations of this starting point. If there is, however, a limit to the degree of simplicity that a living structure can have, this minimum need for complexity acts as a barrier for evolution towards low complexity. Therefore, if evolution starts at the point of minimum complexity it is obvious that only more complex organisms are expected to emerge. The longer the time, the higher the chance that one appears that will be further away from the starting point, meaning more complex than all the others. As a consequence, over deep time it is to be expected that the average complexity increases. This would be more in analogy with a simple, unidirectional diffusion process, but not the result of a systematic trend given by a law-like directionality. With this scenario the increasing complexity during evolution would have no further meaning or significance (see e.g. Carroll S.B. 2001). The obvious consequence would be that man is nothing more than an accident.
Evidently I would not have written this book if in my opinion the second scenario were true. With regard to the validity of this scenario, the most critical question is, how can the starting point emerge, the minimum of complexity that life needs? If this corresponds to something like a prokaryotic type of cell, this minimum would already be quite complex and its appearance needs an independent explanation (Davies P. 1999). In addition, the whole scenario is based on the assumption that evolution is exclusively driven by a gradual selection on fitness and nothing else. But this evolutionary orthodoxy raises important critical questions in itself, which I now wish to discuss in the following.
Is Darwinism the complete truth?
For the following discussion it is important to differentiate between evolution as such and Darwinism. That life is the outcome of an evolutionary process is very well supported and can be seen as a fact. The way however, how evolution exactly occurs is still controversial (see e.g. Eldredge N. 1995 or Gould S. J. 2002). In this regard the prevailing evolutionary theory is based on Darwin's insights that all life has one common ancestor and that descendants with inheritable variants are sieved by natural selection to retain adaptations with a higher reproduction success. The decisive principle identified by Darwin behind natural selection is that the fittest leaves more descendants behind, which was often expressed in the famous quote of the "survival of the fittest"3. Without any doubt, Darwin's concept is of outstanding importance and describes multiple aspects of the evolution of life. As an example, one of its major strengths is the elucidation how to maximize effectiveness under given circumstances (Kauffman S. 2003). However, this concept has also well-known limitations. It is much better suited to explain the modifications of species or forms once they are already existent, but it has difficulties to explain the emergence of a new type of organism or species. In this respect Kaufman once quoted a late nineteenth-century sceptic who formulated it like this: "It is like archiving an apple tree by trimming all its branches". Even if this criticism may be overdone, it points to the central dilemma of Darwinism (see again Kaufmann S. 2003). And because the emergence of new species is so closely linked with the question of how and why life becomes more complex, Darwinism as such does not help very much to explain the biological auto-complexification during evolution.
About 50 years ago DNA was identified as the carrier of heredity, and the molecular basis of all living forms became evident. Subsequently these fundamental insights into the molecular structure of life were combined with Darwin's concept about evolution in a theory often called Neo-Darwinism. The main characteristic of this theory is to see genes as the genuine object of natural selection instead of organisms. But does this focus on genes change the limitations mentioned with regard to an understanding of how evolution can produce complexity? The answer is no. To speak in mathematical terms, genes are necessary but not sufficient to explain life (see e.g. Conway Morris S. 2003 or Rose S. 1997). One may even ask the question, does life in all cases need DNA or can other life-forms on other planets possibly have a different makeup? I do not want to go further into a critical analysis of Neo-Darwinism with its focus on genes, because this was already done by other, more competent authors (e.g. Eldredge N. 1995, Goodwin B. 1994, Gould S. J. 2002 or Rose S. 1997).
So, does this mean that Darwin is wrong? Let it me put like this: in certain circumstances he provides indisputably an adequate explanation; in others, however, not. This may mean that Darwinism needs to be complemented by additional principles. Let's take for instance the role of the environment. In conventional evolutionary thinking the link between life and environment is rather unidirectional. The role of the environment is mostly limited to being a source of selection on fitness (see e.g. Kauffman S. 2003). In certain situations, this may be an adequate approach towards reality, but not in others. As an example, evolutionary processes that take very long periods of time may need a consideration of the mutual influence and interdependence between the environment and the multiplication of biological forms. As the reader will see later, precisely this will become central with regard to biological complexity. Another example would be the role of sexual reproduction. Why do more complex life-forms normally need two genders to reproduce, while simpler forms are often asexual (see e.g. Wesson R. 1991)? In this regard Darwinism can explain how sexually reproducing species are influenced by natural selection, but the theory is struggling to give a satisfactory explanation of why exactly sexual reproduction evolved in the first place (Eldredge N. 1995). In this book I will show that the split of species into two genders can be closely linked with the need for sustainability during the course of evolution. Again this means, Darwinism explains how sexually reproducing species become modified after they have emerged. But to understand why life requires this type of reproduction, additional and complementary principles would be needed.
In summary, while Darwin's basic concept is doubtless correct, it looks as if something fundamental is missing. The focus on natural selection and fitness may explain certain aspects of evolution, but it is very probably much too simplistic to explain others, such as the emergence of biological complexity. In other words, it looks as if Kaufmann is right with his remark that Darwinism is the truth but not the complete truth (Kauffman S. 2003).
Towards a new understanding of life and evolution
This book presents a new theory, the Interaction Theory, which is intended to contribute to a better understanding of life and evolution, by providing in defined terms and principles an adequate explanation why and how biological complexity can emerge. By doing so, the theory provides also a new answer to the question "what is life?".
Decisive for the new theory is the introduction of a sustainability criterion demanding a balance between living forms and their environment. This approach builds on the insight that unsustainable growth as a result of an exclusive selection on fitness represents a major challenge for life. Due to this sustainability consideration Interaction Theory shows that the emergence of biological complexity follows a law-like process, which causes the stepwise self-organization of matter towards increasingly complex biological forms. In this sense the law-like process of complexity increase, as defined in this book, corresponds to an evolutionary algorithm, which transfers an initial state of low complexity into one of high biological complexity. At the end Interaction Theory allows the conclusion that the evolution of increasingly complex organisms becomes inevitable wherever and whenever life is emerging. And with brain complexity as an integral part of this development, the emergence of an intelligent species, like ours, becomes an expected outcome, instead of an accidental, almost improbable event.
In the following I will start by discussing and ordering the known facts about life and evolution in a new way, so that relevant insights about the meaning of biological complexity will become visible. Here, it will also become clear why certain types of interactions are so central that they gave the theory its name. Based on the insights gained, I will then derive the mentioned law-like process of complexity increase, which is at the centre of Interaction Theory.
Before starting, I would like to end this introduction by mentioning the importance of the subject also outside the biological domain. A radically new understanding of how biological complexity emerges can have implications on the way how we see and understand the role of our own species in nature. This means that it does not only concern philosophical questions such as "are we alone in the universe?", but that the potential implications can go further. So we might come to conclusions about the ongoing auto-complexification of our human society, which might stand in sharp contrast to established convictions. A new understanding of the evolution of life as a result of a law-like process towards increasing complexity may therefore be of importance well beyond biology. At the end of the book I will come back to this point.
1I borrow the term deep time from authors such as Gee H. (2000) and will use it in the following to express the very long periods of time necessary for evolutionary processes to occur.
2 I found the expression "law-like complexifying process" in Paul Davies' book "The Fifth Miracle", which expresses very well a non-accidental nature of complexity increase; hence I use throughout this book the term 'law-like process of complexity increase'.
3 It needs to be mentioned that survival of the fittest corresponds to a tautology (see e.g. Eldredge N. 1995), in addition, not the survival as such is relevant for evolution, but the fact of reproducing better than others.
Interaction Theory as presented in this book is a radically new way that describes biological evolution to increasingly complex forms of life. The new theory is intended to clarify the actual meaning of biological complexity and to provide new answers to the so far unsolved questions of why and how organisms became more complex over geological periods of time. In addition, it also puts essential aspects of evolution and life into a new light, such as the reason why sexual reproduction is necessary and what is the meaning of species. On the following pages I will therefore develop Interaction Theory step by step and try to convince the reader of its correctness.
How to approach biological complexity?
What is the best way to come to meaningful insights about why and how biological complexity has emerged during evolution? Obviously the complexity of life in all its details is far too vast to be addressed directly. To come to meaningful insights it is therefore necessary to introduce some kind of model in the form of what can be called an adequate abstraction of reality (Fontana W. and Buss L.W. 1994). This abstraction must reflect the key characteristics of life and evolution, while portraying the essential aspects of reality in a few, well defined terms and principles. In a next step these terms can then be put into relation with each other, so that meaningful conclusions about the emergence of complexity can be derived.
The main criterion to decide whether one specific model is suited or not depends on its results in the sense of: does it explain what has happened during the course of evolution? In the case of Interaction Theory this would mean: does it for example help to understand why the phylogenetic tree of life stretches from structurally relatively simple prokaryotes to highly complex forms, such as oak trees and Homo sapiens? Or can it also elucidate why the biological diversity in the phylogenetic tree is clustered and not gradually organized? Over and above that, however, an adequate model must make it possible to derive meaningful deductions about the real world, which can then be tested and verified (see Lloyd E.A. 1994). An example would be a testable prediction about the emergence of new species.
But what can an adequate abstraction of reality look like? In this respect it makes sense to consider that the emergence of biological complexity is closely linked with the phenomenon of life as such. To come to an adequate model with regard to biological complexity it will therefore be crucial to identify an adequate description of life that makes it evidently different from 'dead' objects. From here on, the desired model can then be built. The whole endeavour to come to meaningful insights about the why and how of biological complexity may therefore depend on this choice.
Now, what makes life so fundamentally different? From the viewpoint of evolutionary orthodoxy the capability for reproduction and heredity based on genes are normally seen as the decisive key features of living forms (see Dawkins R. 1976 or Williams G.C. 1966). This focus on reproduction and genes does not, however, cover the important particularity of biological complexity, namely that it has emerged over deep time. Therefore I want to choose a different and radically new approach. I will put the emergence of generation sequences continuing over deep time into the centre.
The generation sequences of life
In general, life and evolution are linked to the fate of individuals and their genes by focusing on the individual capability to reproduce. However, this does not acknowledge that biological complexity does not emerge in a single generation, but is the result of a slow process over very long periods of time and uncountable generations following each other. For the discussion of complexity increase during the evolution of life it seems therefore more adequate to consider this long process, instead of focusing on individuals. How can this be done? The solution offered in the following is to connect the discussion about biological complexity with generation sequences. Here I mean the following: life has the characteristic of manifesting itself in the form of uninterrupted sequences of generations proceeding over long, geological periods of time. All individual forms living today, be it the uncountable bacteria, alga and protozoa, as well as plants, mushrooms, animals and humans, all have in common the fact of being the outcome of a very long sequence of generations stretching back into deep time to the origin of life. And because it can be assumed that all life on earth originated from a common ancestor (Doolittle W.F. 2000), all generation sequences would have started from the same point. Based on this insight, life and the emergence of complexity can be seen as a process and described in the following way:
These generation sequences can be seen as a kind of chain reaction, driven by a reproduction event in each and every generation. On earth, the chain reaction was most likely kicked off more than 3 billion years ago, and continues to this day (for an overview about evolution, see e.g. De Duve C. 1995). And no foreseeable end exists, because at least some of today's generation sequences may continue as long as conditions exist that allow the reproduction of the respective forms. But not only this, the generation sequences have one other, very surprising characteristic. During their course through time the living forms carrying the generation sequences of life have changed and became more complex. At the beginning, while starting with the last common ancestor of all living forms, all generation sequences were on the same, very low level of complexity. However, this uniformity changed dramatically. In the case of prokaryotes the complexity had relatively rapidly reached a point after which no dramatic changes happened any more over billions of years. On the other extreme, the sequences leading for example to humans have experienced over the course of evolution a progressive complexity increase. Other living forms can be seen somewhere in-between the two extremes. In the following I will try to understand why and how generation sequences can proceed over deep time and cause this pattern of biological complexity.
Interdependence between living forms and environment
The focus on generation sequences has the effect that it becomes crucial to see life and evolution under the aspect of an ongoing process, which needs to be sustainable over deep time. This results in fundamental differences with current evolutionary mainstream thinking. Mainly the interdependence between living forms and their environment does acquire a different meaning and dynamic. Before discussing these differences in detail, I want first to point out some aspects regarding the role of the environment in traditional evolutionary thinking.
Thanks to Darwin, the basic principles of evolution seem to be simple and clear. On the other hand however, their interpretation is often influenced by the relevant zeitgeist (see e.g. Fox Keller E. 1995). For example, in Darwin's epoch, when a bad harvest caused a general famine, nature represented a threat, which demanded the constant struggle to survive. Not surprisingly this is reflected in Darwin's theory, which presents evolution as a history written with teeth, blood and claws (Darwin C. 1859). And obviously, in such a world only the fittest can survive. In a similar way the role of natural selection can be seen as influenced by the zeitgeist of the Victorian epoch. Strict and authoritarian, natural selection rules in absolutism and decides on the fate of all living beings struggling with a merciless environment. Unfortunately this simplistic view of evolution has not completely disappeared since Darwin. Today, in the era of a global economy and its obsession with profitability and performance, the fixation on fitness seems even to be stronger.
An understanding of evolution in the way mentioned ignores completely the fact that living forms do also represent a potential threat to a fragile environment, which may become irreversibly exhausted by fast and self-enhancing growth. Here global humanity gives a concrete example of being directly confronted with the ecological consequences of its fast and strong growth over the last decades. To come to a more adequate interpretation of evolution it would therefore be important to consider much more the close interdependence between living forms and their environment. And this does mean organisms need also to be seen as potential multiplication bombs. They react with exponential growth, whenever favourable conditions appear. One tiny little bacterial cell, much too small to be visible with the naked eye, is able to divide under optimal conditions each and every 20 minutes (Cooper S. and Helmstetter C.E. 1968). As a result the total earth surface can theoretically be covered with a thick layer of bacteria after only 36 hours of exponential growth (Pianka E. R. 2000). Obviously, these dramatic consequences of self-accelerating growth, which can destroy the environment and exhaust resources, must be taken into consideration. This leads to the following conclusion: to understand why life became more complex during evolution demands a holistic view of living forms as potential victims of environmental selection as well as potential perpetrators, which can irreversibly damage the very same environment. Or less prosaically, it needs to be considered that not only the environment influences and alters living forms, but that also the environment becomes influenced and altered by the ongoing multiplication of living forms. This is exactly what Interaction Theory does, by closely linking evolutionary processes with sustainability.
Regarding the influence of the environment it is also necessary to take into consideration that the environmental conditions are not always changing in a gradual or linear manner. Thus, from the generation sequences point of view it is necessary to anticipate that over deep time the environment cannot be stable and does sometimes change abruptly and dramatically (see e.g. Lenton T. & Watson A. 2011). When such sudden and dramatic environmental changes occur, the reactive adaptation by the affected living forms may not be possible and mass extinction occurs. A well-known example of this kind of event happened very probably about 65 million years ago, when a meteorite wiped out the ecosystems dominated by dinosaurs and opened the way for mammals and, in the end, Homo sapiens (see again e.g. Lenton T. & Watson A. 2011). Later I will show that the complexity increase in evolution is driven by this type of catastrophic event and change.
Sustainable generation sequences
The focus on generation sequences and the insight that living forms may exhaust and irreversibly change the environment with self-accelerating growth serves as a key insight for the following discussion of complexity increase. To approach evolution under this aspect means that the long and ongoing generation sequences of life occur in an environment that can become exhausted or destroyed by growth. As the reader will see, it turns out that here lies the key for a better understanding of biological complexity. This brings me to the starting point of Interaction Theory, the introduction of a sustainability criterion demanding a balance between living forms and their environment. This demand results in the following key question:
To start with this question has the advantage that the evolution of complex life becomes tangible. And it will turn out that the answer on how a sustainable multiplication of living forms is possible in an irreversibly exhaustible environment will provide the solution as to how and why biological complexity increases over time, namely by a law-like process.
To direct the reader to this conclusion, I will proceed as follows: first I will identify the key insights essential for generation sequences to travel through deep time in a world with exhaustible resources. Based on these insights, I will then answer the question of why and how in some generation sequences the respective forms become more complex over deep time. This will then lead to a law-like process of complexity increase at the end of the first part of this book. In the second part, I will then discuss the course of evolution on earth, from its beginning up to the appearance of Homo sapiens, under the aspect whether it has indeed followed the identified law-like process of complexity increase. This means I will use the gained insights and conclusions in order to show that they are in line with what has happened in reality. At the end the reader may decide whether or not Interaction Theory is appropriate to explain the emergence of biological complexity during the evolution of life.
In the following I will define the conditions which are necessary for generation sequences to travel through deep time. This provides the framework or model for the subsequent discussion of why life results in living beings of different complexity.
Multiplying forms, generation sequences and complexity
In biology life is normally closely linked to the appearance and characteristics of cells. On the other hand, from the point of view that the self-organization to higher complexity is an ongoing process over deep time, the cell is merely more than an intermediate step. Evolution started very probably with relatively simple molecules evolving into more complex molecular entities, which then aggregated into cells, of which over time some organized into multi-cellular organisms and resulted in the manifold diversity of herbal and animal life (see e.g. De Duve C. 1995). With the arrival of Homo sapiens, this process of complexity increase finally entered into a new phase, which is characterized by a cultural, scientific and economic evolution towards more and more complex societies (see e.g. Tattersall I. 1998). To understand why life on earth became increasingly complex, I will therefore focus on the process as such and not on particular biological entities, such as cells. As a consequence, the expression form or forms will be used throughout this book as synonym for all possible entities of life such as cells, organisms or the molecules at the beginning of evolution. Generation sequences can therefore be carried on by different types of forms, ranging from molecules to human beings. This simplification makes it easier to concentrate on the process and to ignore, at least for the moment, the differences between the particular forms.
With regard to respective forms it is further assumed that they are distinct entities with the capability to reproduce, either alone or with a partner. Further, they do not need to consist of one physical unit; they can also consist of different parts forming some kind of organizational structure, such as a chemical network or an ant colony. It is essential that the subparts of such a composed form can no longer reproduce independently, but need the whole entity. This means generation sequences causing forms can show what I called in the introduction the organizational aspect of biological complexity.
What else can be said about generation sequences causing forms? Most important, they must follow Darwin's concept that descendants with inheritable variants are selected, to retain adaptations with a higher reproduction success (Darwin C. 1859). In other words, generation sequences are carried on by forms with the capacity of reproducing in a way that the next generation shows inheritable variations and is therefore not 100% identical with the previous. The variations or differences between the individual forms in each and every generation then influence the fact that some of them can carry their sequence further on, while others not.