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Andrew P. Smith, who has a background in molecular biology, neuroscience and pharmacology, is author of e-books Worlds within Worlds and the novel Noosphere II, which are both available online. He has recently self-published "The Dimensions of Experience: A Natural History of Consciousness" (Xlibris, 2008).

Darwinism
Evolving

Andrew P. Smith

Summary

Darwinism, in its modern or "synthetic" form, is accepted by a consensus among evolutionary biologists as the major explanation of how different forms of life arose. Many critics of the theory, however, including a significant number of scientists as well as philosophers, argue that random variation and natural selection can't account for major evolutionary transitions, including the emergence of not only complex new adaptations in organisms, but entirely new levels of existence, such as the first cells and the first multicellular organisms. To address this problem, many alternative theories have been advanced; most of these postulate various kinds of self-organizing processes, in which certain forms of existence can undergo discontinuous changes and form a more complex or ordered state. However, while often supported by evidence, most of these theories have not been directly demonstrated to produce the kinds of higher order actually found in cells and organisms.

I show here that a more generalized version of Darwinism, in which random variation has multiple meanings on multiple levels of existence, may be able to account for a wide variety of evolutionary changes, including not only translation (changes in life within a single horizontal plane or stage of existence), but transformation (movement from one stage to a higher stage within the same level of existence) and transcendence (evolution of a higher level of existence). In this theory, Darwinian processes operate in analogous ways on different levels of existence. This allows us to develop and test theories on one level, for which we have evidence, then apply them to another level, where evidence may not be available. It also suggests that insights into evolution on lower levels of existence can help us predict our own future evolution.

Introduction

Nearly one hundred and fifty years after its formulation, Darwin's theory of evolution remains one of most widely accepted and influential scientific theories of all time. Yet a large and vocal minority in the academic and scientific community has long insisted that the theory is incomplete, that there are many evolutionary transitions, or gaps, that it can't account for (Taylor, 1983; Lima-de-Faria, 1988). While few dispute that Darwinism accurately describes the process by which new species of any particular organism arise, its ability to account for the evolution of new phyla or classes of organisms, as well as the emergence of the first cells and the first organisms, has been repeatedly called into question.

To address this problem, many alternative evolutionary theories have been proposed in recent years. The great majority of these theories postulate some kind of self-organization, that is, a process by which one form of existence can develop into a higher, more complex or more ordered form of life, more or less spontaneously. Examples of such theories include cellular automata (Wolfram, 1994), autopoiesis (Maturana and Varela, 1992), dissipative structures (Prigogine and Stengers, 1984), chaos (Gleick, 1988) catastrophe theory (Thom, 1989), criticality (Bak, 1996) and autocatalysis (Eigen, 1971; Kauffman, 1995). Most of these theories are supported by evidence, that is, observations that some self-organizing processes do occur which are accurately described by the theory.

Nevertheless, as explanations of evolution, all of them have serious weaknesses.

1. First, it's one thing to demonstrate that a process can create a more ordered state; it's quite another to show that it can create a specific kind of ordered state. Dissipative processes, for example, can create a certain kind of order in selected chemical reactions; they have not been demonstrated to create the kind of order found in metabolic processes in living cells. Cellular automata can form a variety of computer-simulated patterns that sometimes closely resemble the morphology of real organisms. However, it has not been shown that real cells form tissues using the kind of rules by which cellular automata generate their patterns.
2. A second limitation of theories of self-organization is that they don't adddress the fundamental question of how information storage evolved in the form of a specific structure. A key process in evolution, particularly in the emergence of new levels of existence such as cells and organisms, is the ability to reproduce. In order for a cell to reproduce, it must have information representing, directly or potentially (epigenetically), all of its subcellular components. This information, contained in the DNA sequences of genes, is highly specific. While the evolution of the genome poses major problems for any theory based on the gradual accumulation of small changes, most self-organizing processes have thus far been able to shed even less light on this process.
3. A third limitation of self-organizing theories is that they depend on certain defined conditions or properties of the evolving entities. For example, autocatalysis, an interesting and quite plausible theory of how primitive metabolic networks might have evolved, takes as its starting point the existence of fairly large and complex molecules that can be converted into other molecules. The theory does not explain, however, how these molecules originated. Some other self-organizing theories, such as chaos, catastrophe theory and criticality, are even more sensitive to starting conditions. This problem does not mean that such theories aren't potentially useful in accounting for certain evolutionary events, but it does suggest that they could not function as a broad description applicable to many events.

In this same context, another problem for many, though not all, theories of complexity or self-organization is the presence of repeating themes in evolution. As I will discuss shortly, there is growing support for a hierarchical or holarchical view of life, with new levels of existence transcending and including earlier ones. Though new features emerge at each new level, the processes on each level also seem to retain significant analogies to those on other levels (Ouspensky, 1961; Land, 1973; Smith, 1999a). That is, forms of life on different levels have very similar fundamental properties, patterns of organization, and types of interrelationships.

Though most complexity theorists accept some kind of hierarchical view, they don't seem to realize that the existence of such regularities is not easy to reconcile with the indeterminacy and creativity at the heart of many of their theories, such as dissipative structures, chaos and criticality. Thus philosopher Michael Polanyi suggests that evolution is simply "a progressive intensification of the higher principles of life"[2] already present in the lowest forms of existence. Going even further, Lima-de-Faria argues that "biological evolution...became a prisoner of...previous evolutions. The laws and rules they followed created the frame from which biological evolution could not and cannot depart."[3] Lima-de-Faria's view of evolution, which is also based on self-organizing processes, thus provides a useful counterpoint to the more usual emphasis of such theories on spontaneity and unpredictability.

Finally, we might justifiably criticize self-organizing theories, ironically, on the grounds that the changes they propose are too large, too sudden. A perennial criticism of Darwinism is that it takes too long, that there simply hasn't been enough time for the forms of life we see today to have evolved through random variation and natural selection. This criticism, however, can be turned around and applied to theories of self-organization. If major evolutionary transitions could have occurred very rapidly, why has evolution taken as long as it has? If, for example, processes such as autocatalysis and dissipative structures enabled many of the components of early cells to emerge quickly, why did it take billions of years for cells to evolve? If cellular automata are a valid model of the formation of organisms from cells, why did this evolutionary process take an additional several hundred million years?

I don't wish to sound too disparaging of these theories, most or all of which provide important new insights into issues other than evolution. It will probably be some time before their full potential can be evaluated. In addition, other alternative evolutionary theories that don't depend on self-organization, such as Sheldrake's morphogenetic fields (1981, 1989), unquestionably do have the potential, if verified, to explain many currently unexplained evolutionary transitions. Before we give up on Darwinism, though--our first and some would say still the only unifying theory of biology-- we ought to be certain that we have taken it to its limits. The evolutionary events that nearly everyone concedes it does explain are so universal, and have occurred over such an immense length of time, that it seems unlikely that it's just one odd piece in a much more complex puzzle. If random variation and natural selection operate at one level of evolution, we ought to ask why other levels should be governed by totally different principles.

This is the basic question that motivates this paper. What I propose to do is show that a broader, more generalized version of Darwinism--one retaining the key concepts of random variation and natural selection, but interpreting these in multiple ways--has the potential to explain far more of evolution than the current "synthetic" theory of evolution that is supported by most Darwinists today. My approach is based on a hierarchical or holarchical view of existence, so I will begin with a brief summary of this view. I will then show that this holarchy implies three different phases of evolution, that repeat themselves on every level of existence. Each one of these evolutionary phases can be driven by a different kind of Darwinian process, or a different combination of several of them, and the sum of these processes suggests a much more comprehensive form of the theory, one applicable to existence at all levels.

The Holarchical View of Life

The concept of hierarchy, or holarchy, is gaining increasing acceptance as a critical principle in any comprehensive understanding of existence (Ouspensky, 1961; Land, 1973; Jantsch, 1980; Wilber, 1990, 1995; Smith, 1999a). In its most radical form, this view asserts that all forms of existence are holons, which are simultaneously wholes and parts--that is, complete in some sense in themselves, yet also parts of other, higher-order holons. Each higher order holon includes lower order holons, but also exhibits new, emergent properties.

Different models of the holarchy have been proposed, but there is general agreement on the main outlines, which include atoms, molecules, cells, and organisms. I recently proposed a model with these basic components, but organized into both levels of existence and stages within these levels (see Table 4 ; this table is taken from the book Worlds within Worlds).

Fundamental or autonomous holons are in bold, and mark the end of one level of existence and the beginning of the next. Some examples are taken from Stryer (1988) and Clemente (1985). Some assignments are only approximate, because the stages as I define them (see text) do not always correspond to traditional physical, chemical, anatomical or social classifications.

The rationale for this model is that certain kinds of holons, which I call fundamental or integrated holons have somewhat different properties from those that I call social holons.

Fundamental holons, including atoms, cells and organisms,

1. can exist independently of higher-order holons as well as within them (thus cells are found in organisms, but also as unicellular organisms);
2. are able to reproduce (with the exception of atoms); and
3. not only have new, emergent properties not found in their component holons, but preserve all the properties of the latter.

Social holons, in contrast, generally can't exist outside of higher-order holons; generally do not reproduce; and do not preserve all the properties of their component holons (though we will see some exceptions to these rules later).

Based on this model of the holarchy, two kinds of evolutionary changes can immediately be distinguished. I define transformation as the process by which holons within a level combine to form new, higher-order holons within that level. For example, the formation of a protein from amino acids is a transformative process. I define transcendence as the process by which all the stages on one level became combined into a new fundamental holon representing the beginning of a still higher level of existence. The emergence of cells is an example of a transcendent evolutionary process.

Based on this view of the holarchy, any comprehensive evolutionary theory should include the processes of both transformation and transcendence. That is, it should provide an explanation of how holons combine to form new stages of existence, as well as how several of these stages then combine to form a new level of existence. Moreover, since there is considerable evidence that holons on one level of existence are analogous to holons on another (Ouspensky, 1961; Land, 1973; Smith, 1999a), we might further anticipate that evolutionary processes on one level would be analogous to processes on another.

In addition to these two recurring evolutionary themes, however, there is a third. After a new level of existence has been formed--an atom, a cell, or an organism--there is a process of diversification or translation (Wilber, 1990), in which many new kinds or classes of that holon evolve. (In conventional evolutionary theory this is called adaptive radiation, though the term conventionally applies only to organisms.) Thus many different kinds of atoms were formed some time after the origin of the universe, billions of years ago; many new kinds of cells evolved after the initial emergence of this new form of life; and many kinds of organisms evolved following the appearance of the first multicellular holons. Diversification may also occur on different stages within a level of existence; there are many different kinds of protein molecules, and many different kinds of same-stage biological tissues.

In summary, evolution of the holarchy proceeds in three phases, which recur on every level of existence: diversification, transformation, and transcendence[4]. I will now discuss each of these evolutionary phases in a little more detail, so that we will have a better idea of what any comprehensive evolutionary theory needs to address.

Diversification

Evolution, in the Darwinian view, is a highly selective process, in which many compete, but few survive. Though Darwin came to this conclusion from his observations of organisms, evidence for selection is evident at other levels as well. Of the nearly one hundred naturally-occurring elements, only four--carbon, hydrogen, oxygen and nitrogen--are major constituents of higher forms of life. Of the many kinds of cells, probably one or a few basic types formed the first orgnisms . Of the many kinds of organisms, only human beings are capable of associating into complex forms of social organization.

Seen in this light, diversification is not entirely distinct as a process from transformation. Given that only certain kinds of fundamental holons are able to form higher-order social holons, it follows that any process that greatly increases the variety of fundamental holons also increases the chances that higher stages can form. The wider the variety of building materials we have, the better the structure we can erect.

There is, however, one primary property of a fundamental holon that recommends it to the formation of higher stages. This its ability to form hetarchical (horizontal) interactions with other holons of its class, that is, to communicate with them. Thus the key role of carbon atoms in all higher stages and levels of life derives from their ability to bond with four other atoms simultaneously. Likewise, eukaryotic cells have the ability to form associations with other cells of their kind, through the interactions of specific molecules on their surface membrane. Human beings have by far the most sophisticated forms of communication of all organisms.

What is it about these types of holons that makes them so adept at communicating, at interacting with other holons of the same type? On the mental level of existence, the answer is obviously our well-developed brain. As a general rule, the more evolved an organism's brain, the more complex the social organization it forms[7]. Our own species has the most evolved brain of all, and forms by far the most complex social groups. On the biological level, on the other hand, communication correlates with the size of the genome. Eukaryotic cells, which are present in all multicellular organisms, have much larger and more complex genomes than prokaryotic cells, which do not associate into organisms.

We can regard the brain and the genome, then, as equivalent social holons on their respective levels of existence. Both of them are essential to the process of communication that enables the fundamental holon in which they exist (cells and organisms, respectively) to form higher-order holons. Their role is most easily appreciated if we adopt the traditional definition of communication as transmission of information. When one cell communicates with another, it generally does so by presenting a certain kind of molecule to the latter, either directly in physical association, or indirectly, as through communication by hormones or neurotransmitters; the second cell, by recognizing this molecule with another molecule of its own, accepts this information. Likewise, when human beings communicate with one another, they present information about themselves or about other holons to each other.

Just as a large brain enhances the ability of organisms to communicate with one another, by increasing their repertoire of potential behavior, so a large genome enhances the ability of cells to communicate with one another, by enhancing their repertoire of signalling molecules.Every molecule that a cell uses to communicate with another cell must be encoded by a distinct gene (or synthesized in a process involving an enzyme that is a product of some gene), so the more genes a cell has, the greater the potential variety of communicative interactions it can make with other cells. Humberto Maturana, co-developer of the theory of autopoeisis, defines communication as "coordination of behavior"6, and the larger the gene or the brain, the more sophisticated such coordination can become.

A key event in diversification, then, is the emergence of fundamental holons with the capacity to store large amounts of information. All of this information may be required in some manner to form higher-order social holons. However, since different fundamental holons play different roles in this process of forming higher stages, no individual holon of this kind uses all of the information available to it. This leads to a distinction between the deep structure and the surface structure of information. This is a critical point, because each type of structure can change, and as we will see later, depending on which does change, a different evolutionary process results.

Consider the genome first. Every cell in the body contains all the genetic information that every other cell contains. The sum total of all this genetic information is the genome's deep structure. But cells in different parts of the body differ according to which genes they express, that is, which genes are active in the synthesis of the proteins they encode. Cells in the heart express certain genes, and don't express certain other genes; cells in the liver express a different set of genes; and so on. Furthermore, even a particular type of cell may express certain genes at one time, other genes at another time. The particular pattern of genes expressed by any given cell at any given time represents its genetic surface structure.

The same distinction can be made in the brain. The brain has the potential to perform many kinds of behavior, and we can say that every member of a species has roughly the same potential. This potential, the brain's deep structure, is rooted in the relatively gross, hard-wired anatomy of the brain. But different members of the same species may express different kinds of behavior, and one member may express different behaviors at different times. What behavior any one individual expresses at any one time is part of the brain's surface structure.

Transformation

Transformation is the process by which fundamental holons combine to form higher order holons within a single level of existence. We have seen that it proceeds, to some extent, hand in hand with diversification. Thus as cells continued to diversify, higher stages of biological organization became possible. Likewise, as organisms diversified, higher stages of social organization emerged.

Many, perhaps most, of the major evolutionary transitions that occurred within organisms--the kind of transitions that Darwin's critics have long used as evidence of the theory's weaknesses--evolved during this period when higher, transformative changes were occurring as well. Thus as I noted earlier, there is a correlation between the complexity of an organism's brain, and the complexity of the social groups it forms. In this sense, we can say that evolution of the higher vertebrates, though a diversification process, was also a transformative one. Indeed, transformation was occurring simultaneously on two different levels of existence--on the biological level, in the emergence of more complex brains, and on the mental level, in the emergence of more complex societies.

An important question to ask, then, is whether diversification of fundamental holons on any one level of existence is ever really distinct from transformation. At first glance, the answer would appear to be yes. The first eukaryotic cells are thought to have emerged about one billion years ago, and the modern complex genome probaby within a few hundred million years after that. But new stages of biological organization, notably the human brain, continued to evolve until less than one hundred thousand years ago. Likewise, the biological evolution of human beings was essentially completely 50-100 thousand years ago (with the completion of evolution of the human brain), yet new and higher forms of social organization are still evolving today.

These distinctions become less clear, though, when we consider evolution of both deep and surface structures. While the deep structure of the genome was probably complete between one billion and six hundred million years ago, the surface structure--processes for selectively expressing different genes--probably continued to evolve for hundreds of millions after that. In the same manner, while evolution of the deep structure of the human brain may have been completed one hundred thousand years ago, its surface structure is continuing to evolve today. So a general rule seems to be that diversification of deep structures of fundamental holons precedes transformation of those holons, while diversification of surface structures parallels transformation.

This last point, as we shall see, helps illuminate a vexing problem for Darwinism. Transformation involves the creation of social holons, and as I noted earlier, these are not autonomous and do not reproduce. This is an extremely significant point, because Darwinism depends centrally on reproduction. Natural selection presupposes competition among holons which is ultimately decided by superior reproduction ("reproductive fitness" in evolutionary terms). In order for higher stages to evolve through Darwinian mechanisms, therefore, either they must have had the ability to reproduce during the period of their formation (which they later lost when the new higher level organizing them emerged), or their formation must in some manner have improved the reproductive fitness of the fundamental holons composing them. Indeed, Darwinism's apparent difficulty in explaining this process is a major reason why self-organizing theories, which don't (necessarily) depend on selection, have appeared so attractive to some theorists.

Transcendence

Transcendence is the third and final phase of evolution, completing a new level of existence. To repeat what I said earlier, the new, fundamental holons created through transcendence differ from social holons in three significant ways:

1. They are autonomous, capable of existing outside of higher-order holons.
2. They can reproduce themselves.
3. They preserve all the properties of the social holons within them.

The first two of these features are obviously very closely related. If a holon is to be capable of existing autonomously, it must be able to reproduce itself. Leaving aside point 3) for now, I will therefore consider the emergence of reproduction as a central feature of transcendence. In fact, I will use it to offer a new definition of transcendence: the process by which a group of holons acquires the ability to reproduce itself.

Why is reproduction such a special process? I have argued previously (Smith, 1999a) that all holons (social as well as fundamental) share three fundamental properties: assimilation, adaptation and communication. Each of these properties can be defined in terms of interaction with other holons. In assimilation, a holon interacts with a lower-order holon; in adaptation, it interacts with a higher-order holon; and in communication, it interacts with a holon on its own stage and level of existence. Reproduction is unique in that it's the only property of a holon that does not involve interaction with another holon[5].

What does reproduction require, then? First and foremost, it requires information. Since a fundamental holon contains and organizes all the stages on the level of existence below it, all these holons must be reproduced in the process of reproducing the fundamental holon. This can only be done if the latter has information about them, information that, in effect, enables it to duplicate each of them.

In the discussion of diversification, we saw that within any fundamental holon, information is contained in a specific higher stage holon. This holon is the genome in the cell, and the brain in the organism. (And on the sub-physical level, though I will not discuss it here, it's the atomic nucleus). This informational holon plays a dual role. It in effect points in two directions, towards the stages below it, and to the level above it. On the one hand, it contains all the information necessary to organize or actualize all the stages below it; thus the genome contains all the information needed to synthesize all the proteins in the cell, and the brain contains all the information needed to regulate the functions of the body. Given the synthesis of proteins, all other components of the cell can be formed; likewise, given the regulation by the brain, all the other functions of the organism can be manifested. This is reproductive information.

On the other hand, this informational holon also contains the potential to create a still higher fundamental system on the next level of existence. Thus the information in the genome is sufficient to create all the different cell types of the organism; and as I have argued elsewhere (Smith, 1999b), the brain of a human being in a highly advanced society would contain all the information needed to specify a higher level of existence--i.e., to colonize another planet. This is communicative information. This dual nature of the informational holon is also reflected in the observation, noted earlier, that evolution of the brains of higher organisms proceeds hand-in-hand with that of their social groups, and that of genomes in higher cells hand in hand with primitive organisms.

In conclusion, any evolutionary theory that would adequately explain the process of transcendence must account for the evolution of this informational holon. If we are to understand the evolution of cells, we must understand how the genome evolved; if we are to understand the evolution of organisms, we must understand how the brain evolved. This may seem obvious, but as I pointed out earlier, most alternatives to Darwinism that have been proposed to explain large evolutionary changes really do not address this problem. They are much better suited to accounting for transformative, rather than transcendent, changes. While self-organizing theories may present a plausible scenario by which higher or more complex forms of organization emerged from lower ones, they generally don't and can't explain how the higher forms came to have all the information needed to replicate the lower forms. Without this information, the new emergent holons can't reproduce themselves. If they are unable to do this, no diversification is possible, and the entire evolutionary process comes to a halt.

Levels of Darwinism: Biological, Cultural, Transcultural

With this understanding of evolution in the holarchy as background, let's now try to see how Darwin's theory fits into the picture. The modern, up-dated version of this theory, usually known as "synthetic" theory, differs somewhat from Darwin's original version, but since my main aim here is to search for a very general metatheory based on Darwinism, I'm going to ignore these differences for the most part. The key concepts in both the original and the modern version are random variation and natural selection. Random, heritable variations in organisms occasionally result in some new feature (anatomical, physiological and/or behavioral) that enhances reproductive fitness--that is, the ability to reproduce more often, or in greater numbers, than organisms not possessing this variation. As a result, organisms with this variation become established in the population. When such variations accumulate over time (along with certain other factors promoting separation of part of the population from the rest), a new kind of organism may emerge.

Based on our earlier discussion, we can now see immediately that Darwinism is largely a theory of diversification (translation), and diversification on only one level of existence at that. It's an explanation of how organisms, the fundamental holon on the mental level, evolved into a great variety of species from which one, our own, was able to form higher stages on this level. However, we have seen that diversification to some extent accompanies transformation. To the extent that Darwinism is capable of explaining the emergence of higher vertebrates, it's also capable of shedding light on how higher stages of biological organization (the brain) and of mental organization (social groups) occurred.

Furthermore, while Darwinism was not originally intended to account for evolution of life before the emergence of organisms, it can be, and now is, easily extended to one major earlier evolutionary period--the diversification of cells. When Darwin wrote, he was not aware of the genetic basis of heritable variations in organisms; it was only in this century that the role of gene mutations in this variation was discovered. This discovery makes it clear that cells, too, can be potentially subjected to natural selection. For example, we can well imagine an early population of single-celled organisms, in which a mutation occurred giving one of these cells a survival advantage--a more efficient step in one of its metabolic pathways, for example. When this cell reproduced itself by dividing, the new gene was passed along to the next and all succeeding generations[8]. These mutant cells, being more efficient than the original variety, eventually might have taken over the population.

The basic principles of Darwinian evolution, therefore, are retained at the level of the cell. In fact, we could say that evolution at this level is a purer form of Darwinism, because the two key processes of mutation and selection interact more directly. Evolution at the level of the organism is somewhat complicated by two factors that intervene between mutation and selection. First, organisms do not, of course, reproduce by dividing themselves like cells; they instead produce special reproductive cells, or gametes, which later develop into a new organism. Ordinarily, only mutations in these gametes are transmitted to the organism's descendants. And second, the path connecting the mutation in the gene to the variation in the organism is very complex, since it in effect must traverse all or part of two levels of existence. First, it must result in some variation in cells; then in various higher stages of these cells; and finally in the organism itself. As molecular biologist Jacques Monod pointed out (1971), this gauntlet that the mutation must pass through--an organizational series of stages and levels with which it must be compatible--screens out most of them before their effects even reach the phenotypic (biological or behavioral) level.

For this reason, I propose to use Darwinian evolution at the level of the cell as the core theory of diversification in the holarchy. That is to say, in attempting to generalize Darwinism to other types of evolutionary processes, we will take as its basic statement the form in which it applies to the cell. This can be put as follows:

Mutations occur (randomly and rarely) in the (atoms of the) genes of a cell. Some of these mutations result in a change in the properties of the cell. If a new property provides the cell with a survival advantage over other cells, the altered gene becomes established in the population of cells.

What I now propose to do is show how this statement, intended to apply to a specific level and a specific stage in the holarchy, can be generalized to other stages and levels. To do this, I will use a process I call holon substitution. First, I re-cast the statement in terms of the holarchy, that is, I replace specific terms such as "genes" and "cells" with more general terms such as "social holons" and "fundamental holons". This more generalized version can then be applied to other levels of existence.

To begin the process, here is how we restate the theory in terms of the holarchy:

Variations occur (randomly and rarely) in fundamental physical holons (atoms) of a higher-stage physical holon (the genome) in a fundamental biological holon (the cell). Some of these variations result in a change in the properties of the biological holon. If a new property provides the biological holon with a survival advantage over other holons of its class, the altered higher-stage physical holon becomes established in the population of biological holons.

This statement may seem awkward and hard to understand compared to the first statement, but cast in such general terms, it can now be applied to other levels of existence. To do this, we substitute for all terms that refer to a specific level of the holarchy other terms (which I have underlined) that refer to equivalent holons on the next higher level:

Random, rare changes occur in fundamental biological holons (cells) of a higher-dimensional biological holon (the brain) in a fundamental mental holon (the organism). Some of these changes result in a change in the properties of the organism. If a new property provides the organism with a survival advantage over other organisms, the altered brain becomes established in the population of biological holons.

Does this statement actually describe a known evolutionary process? Yes--more or less--and it is otherwise known as cultural evolution. Cultural evolution results from a behavioral change in organisms--usually, but probably not always, human beings--which is then transmitted to succeeding generations through learning. Though cultural evolution is distinct from what is commonly referred to as biological evolution, the former does have a definite biological component. The initial variation or "mutation"--a new idea, a new way of looking at or doing something--is presumably a change in the pattern of connections between certain neurons in the brain. This pattern is what is transmitted when other organisms learn it, and is what eventually becomes established in the population.

At this point, an evolutionary biologist is likely to object that the analogy between cultural evolution and Darwinian evolution is imperfect. In Darwinian evolution (at the cellular level) the unit of reproduction is the cell; a change occurs in the genes of the cell, and the cell transmits the genetic change to succeeding generations by reproducing itself. If the analogy with a higher level is to be complete, it would seem that the organism should be the real unit of reproduction--just as was stated in the substituted form of the theory I presented above. For the organism is to its level of existence what the cell is to its.

In cultural evolution, however, the unit of reproduction is not the organism. For the selection of the new behavior does not depend on organisms which exhibit this behavior reproducing themselves more succesfully than organisms without the behavior. Rather, the behavior itself seems to be reproduced; the competition is between the new form of behavior and some earlier form that it replaced. Thus if I have a new idea, and succeed in transmitting this idea to the rest of society, I do not reproduce myself. Rather, the idea reproduces itself.

Cultural evolution then, is not truly analogous to Darwinian evolution on the cellular level, because the units of reproduction on the two levels are not equivalent. But what exactly is the unit of reproduction in cultural evolution? A moment ago, I said it was the idea, or some other mental product; this is conventionally referred to as a "meme" (Dawkins, 1976). But like everything else, this term can be expressed more precisely in terms of some kind of holon. I have argued elsewhere (Smith, 1999a) that ideas and other mental phenomena represent higher-order holons--that is, groups and other forms of social organization--as we see them from our position in the holarchy. Therefore, it follows that in cultural evolution, the unit of reproduction is the group[9]. What is actually being reproduced, and in this way being transmitted, is a new set of interactions between individuals. This is true regardless of whether the transmission is vertical (parent to offspring) or horizontal (from one member of a generation to another).

We can see this very clearly with language, which is often cited as an example of a phenomenon that emerges through a process of cultural evolution. Language is a means of communication between individuals, and thus alters the way the individuals interact. Therefore, when a language emerges among a group of people, and is transmitted from generation to generation, we can say that a particular way of communicating, or a particular kind of social organization, is also being transmitted. As sociologist Niklas Luhmann says, "Social systems use communication as their particular mode of autopoetic reproduction[10]."

This is an extremely significant point, for when social interactions among individuals evolve, as well as the individuals themselves, we may no longer be dealing purely with diversification processes. We may also be dealing with transformative processes, that is, the evolutionary events that result in the emergence of higher stages within a level of existence. I say may be, for cultural evolution, defined in the precise way that I'm using it here, may simply result in diversification of a social holon; it may, for example, change the properties of a social group, without changing its complexity. Even if this is the case, however, such diversity, as we have seen earlier, contributes to transformation by creating holons that are more capable of associating with each other into higher-order holons. As we will see later, this has implications for our understanding of transformation at other levels of existence.

For now, however, let's continue the process of "holon substitution" that we began above. Let's take our original formulation of Darwinian evolution, stated in holarchical terms, and change the terms again, this time by not one level of existence, but by two:

Variations occur (randomly and rarely) in fundamental mental holons (human organisms) of a higher-dimensional mental holon (the culture) in a fundamental transmental holon (the planet). Some of these changes result in a change in the properties of the planet. If a new property provides the planet with a survival advantage over other planets, the altered culture becomes established in the population of biological holons.

What sort of evolutionary process would this be? Changes in people result in changes in society which change the planet. Does it make any sense?

Think of a large organization, such as a corporation or a nation, in which a leadership change occurs. A person in position of power dies, or retires, or through some other chance event is removed or transferred from that position. This results in a signficant change throughout the entire organization, affecting in turn the entire organization of humanity on earth.

If this sounds far-fetched, reflect on the assassination of John Kennedy, and all the consequences that followed it. Or the death of Martin Luther King. It is, of course, quite rare that the death or replacement of a person has a major impact on the entire earth, but that is just what we would expect. Most mutations in genes have no impact on the cell or the organism--and of those few that do, most have a negative effect and are selected out. Likewise, most changes in human behavior don't result in new social patterns. An essential element of Darwinian theory is that variation is not only random but rare.

Our ability to fully accept that this kind of process might actually occur is of course hampered by our lack of understanding of what a higher, planetary level of existence would be like. Even less can we imagine how such a holon might be competing with other holons of a similar nature. This kind of evolution suggests a hypothetical time far in the future when we might be aware of many other planets with advanced civilizations, all of them in some sense competing. The survivors would propagate their kind, until one portion of the universe, say the galaxy, contained only civilizations of one type.

We do not really have to accept such a far-our scenario, however. The important point is simply that such changes in higher forms of social organization can and do occur, and regardless of what impact they might have on some hypothetical higher level of existence, they definitely can have impact on us. There have unquestionably been points in history when a transition involving a single human being affected societies throughout the earth, and through them, affected the way almost all individuals live.

So I conclude that in addition to biological evolution and cultural evolution, there is a third process that I call transcultural evolution. This process is just as distinct from the other two as the latter are from each other. While biological evolution is initiated by changes in (atoms of) genes, and cultural evolution by changes in (cells of) brains, transcultural evolution is initiated by changes in (people of) societies. Each process can change individual human beings: biological evolution by creating a different genetic makeup; cultural evolution by creating a different brain organization; and transcultural evolution by creating different relationships between the individual and other individuals. In the final analysis, however, all three evolutionary processes involve changes in the physical, biological and mental aspects of human beings (See Figure 2).

Darwinism as a Theory of Evolutionary Transformation

Having seen that a generalized version of Darwinism can account for at least some evolution of the higher, social stages of the mental level, we would next like to know whether this theory can in similar fashion account for transformative processes on other levels of existence. Consider, for example, the emergence of the first multicellular organisms from cells. This phase of evolution presumably began after a diversification period in which many different kinds of eukaryotic cells evolved. The question now is, given the emergence of cells such as these, what was the actual process by which they began to combine with one another into higher stages? This is not a question we can address by appealing to any evidence, because this phase of evolution occurred more than 600 million years ago, and left no traces in the fossil record. But given that this phase of evolution is the biological level analog of cultural evolution on the mental level, we might predict that it would proceed by an analogous process.

Let's begin by recalling our earlier discussion about deep and surface structures. Every cell in the body contains all the genetic information that every other cell contains. The sum total of all this genetic information is the genome's deep structure. But cells in different parts of the body differ according to which genes they express. The particular pattern of genes expressed by any given cell represents its genetic surface structure. Likewise, the brain has the potential to perform many kinds of behavior, rooted in the relatively gross, hard-wired anatomy of the brain. This is its deep structure. But different members may express different forms of behavior, and this reprsents the brain's surface structure.

Keeping this distinction in mind, we can say that cultural evolution involves changes in the surface structure of the brain, rather than in its deep structure. That is, when someone has a new idea, and this idea is transmitted to other individuals, the deep structure of the brain--its hard-wired anatomy and physiology--does not change. What does change is how that deep structure is put to use, which is surface structure. Thus the ability to learn a language--not any particular language, but language in general--is thought to reflect the presence of a deep structure in the brain, and is probably not transmitted by cultural evolution[11]. The ability to learn a particular language, such as English, however, is a surface structure, and is transmitted by cultural evolution.

From this it follow that if we wish to find a true analog of cultural evolution on the cellular level--a process that might explain how multicellular organisms emerged from cells, just as societies emerged from human beings--we need to consider a process involving a change in the surface structure of the genome, rather than its deep structure. A change in the genome's deep structure is represented by genetic mutation, and we have already seen that this kind of process probably accounts for the diversification of cells, prior to the emergence of organisms. A change in the genome's surface structure, in contrast, would involve a change in the way cells expressed their genes.

Keeping this in mind, here, then, is how a cellular analog of cultural evolution would proceed. It would begin with a change in the expression pattern of a single cell, just as cultural evolution begins with a change in the brain organization of an individual. That is, the cell expresses a gene it formally did not express, or expresses a different amount of a gene it did express, or possibly stops expressing (represses) a gene it formerly expressed.

As a result of this changed expression pattern, the cell's interaction with another cell or cells is altered. Perhaps they associate more closely, for example, or perhaps they associate in a different physical shape or pattern. This step, again, is analogous to cultural evolution, where a new idea results in a change in the interaction between individuals. As a result of this new interaction, the other cell or cells also change their pattern of expression so that it matches that of the original cell--just as one individual learns a new idea from another. These cells, too, can now transmit the new expression pattern to other cells. As a result, a large number of cells now exhibit an altered expression pattern, and a significant change in the way they associate is possible[12].

We have no way of testing this idea, of course. But beyond the fact that it's based on molecular and cellular processes that are known to exist, we can argue that it should be just as capable of producing new kinds of multicellular arrays (precursors of organisms) as cultural evolution is capable of producing new kinds of social groups. We know that the same kind of process on our level of existence has played a major role in the evolution of both ourselves and our societies; to just the same extent, the hypothetical scenario I have described should permit the evolution of cells and multicellular groups[13].

In summary, we now have identified two kinds of evolutionary processes, both of them fundamentally Darwinian in nature, and both of which are exhibited in analogous ways, on both the biological and mental levels of existence. What is commonly called biological evolution, but what in holarchical terms would better be called fundamental holon evolution, results in diversification of cells or organisms. It begins with a change in the deep structure of the genome, which is transmitted by reproduction of the fundamental holon. What is commonly called cultural evolution, but what I will call here social holon evolution, contributes to the emergence of biological or mental stages, that is, groups of individual cells or organisms. It begins with a change in the surface structure of the genome or the brain, and is transmitted by reproduction of certain kinds of social interactions between fundamental stage systems.

Furthermore, each of these evolutionary processes may have a higher-level analog, which I call transcultural evolution. In this process, a very highly developed social structure is the initial locus of change, which hypothetically would be transmitted through reproduction of a higher level of existence. While we can only speculate on the true extent of analogy of transcultural evolution with evolutionary processes on lower levels, the process, as it affects human beings, seems to be real. As with evolution on the lower levels, it may have two forms, one involving changes in the deep structure of the society (reflected in the ways in which human beings are potentially able to interact), and one in the surface structure (the ways in which they actually do interact).

Transcendence

We have seen so far that Darwinism, interpreted in a very broad way, can potentially account for many transformational as well as diversification processes in the evolution of the holarchy. What about transcendence, though, the emergence of a new level of existence? This is usually considered the greatest challenge for Darwinism, or for any other theory of evolution, for that matter.

As I discussed earlier, the central problem of transcendence is creating a new fundamental holon with the ability to reproduce itself. This, in turn, means the emergence of a store of information about all the lower stages of evolution. Thus the key event in the evolution of modern cells was the emergence of the genome, and the key event in the evolution of organisms was the emergence of a brain or central nervous system.

Evolutionary biologists have long recognized the problem this poses, particularly in the evolution of the cell. Classically, the problem has been posed in terms of a choice, between function and reproduction. Function includes all the properties that allow a holon to grow and maintain itself, properties that I have defined as assimilation, adaptation, and communication. In the cell, all these properties are ultimately controlled by enzymes, protein molecules that catalyze all the metabolic reactions. Reproduction, on the other hand, is controlled by DNA, which contains the information needed to make these enzymes, and which is capable of reproducing itself.

The problem is that while one can imagine a primitive holon evolving that contained many different enzymes and the metabolic reactions they catalyze, and one can also imagine a primitive holon that contained DNA, and was able to reproduce itself, it's very difficult to conceive of how a holon with both properties emerged. Somehow, the information represented by the proteins must get into the DNA.

In the past decade, however, a major breakthrough has been made that has convinced many scientists that a solution to the problem exists. This is the discovery of ribozymes. These are nucleic acid molecules that also have catalytic activity; thus they contain both reproductive/informational properties as well as functional ones. In the past few years, many different kinds of ribozymes have been discovered or actually created by a selection process in the test tube (Joyce, 1992), and from studies of these scientists are beginning to develop a plausible scenario of the evolution of cells (Horgan, 1996; deDuve, 1996; Campbell et al. 1999).

A detailed discussion of such a scenario is beyond the scope of this paper. What I would like to do instead is consider, in very general terms, the possibility of an analog of this kind of evolution on the next higher level of evolution, that is, in the emergence of the first complete organisms. We have already seen how Darwinian processes might have contributed to the evolution of multicellular arrays capable of selection. What further steps would be necessary for these arrays to evolve into organisms?

I pointed out earlier that the brain is the biological level analog of the genome on the physical level. Just as the genome controls reproduction in the cell, the brain controls reproduction in the organism. It obviously does not do this in a physical sense--the reproduction of tissues and organs in a new organism--for this, too, is controlled by the genome. The brain controls reproduction in a biological sense--that is, it contains the information needed to regulate the functions of these tissues and organs--to control respiration, heartbeat, gastrointestinal processes, muscular movements, and so forth. In all but the most primitive organisms, a brain or centralized nervous system controls the activity of all the body's organs by sending regular messages to them. It follows that all of the latter--the major organs and tissues (more precisely the activity of these organs and tissues)--are the biological analog of enzymes.

During the evolution of the first organisms, there were probably both multicellular functional arrays--primitive organs capable of digesting food, circulating nutrients, movement, and so forth--as well as multicellular reproductive arrays--a primitive nervous system capable of encoding information in the patterns of connections among excitable cells. As with evolution of the cell, one could imagine either type of array evolving independently. That is, some cells could have associated into primitive organ-like structures capable of carrying out certain functions, and other cells could have evolved excitable properties allowing them to associate into primitive nervous systems. The key issue is how both types of holons evolved together, in such a way that the nervous system contained patterns of information capable of regulating the activity of the organs.. This problem, I suggest, was just as difficult to solve as the genome versus protein problem, and I further suggest that it was solved in the same way as the emerging cell may have: by the emergence of a hybrid holon capable of both function and reproduction.

What would such a hybrid holon be like? As a ribozyme can both contain reproducible information (nucleotide base sequences) and function (catalytic enzyme activity), a hybrid biological holon would be capable of functioning simultaneously like a nervous system and a functional organ. Such a holon still exists in most organisms today, including ourselves: the heart. Though the activity of the heart, like that of other internal organs, is regulated by centers in the brain, it also has some ability to regulate itself. Much of this activity is controlled by the atrial sinus node, muscle tissue which has excitable properties like nervous tissue. In addition, in the absence of control from the sinus node, other parts of the heart can also control its activity. This is why the heart can be completely removed from the organism, severed from all of its connections with other organs, and still beat.

In addition to the heart, there are other internal organs with the ability to function to some extent in the absence of control from the central nervous system. The intestine is innervated by a very primitive kind of nervous system that induces rhythmic contractions in the smooth muscle lining this organ. The vas deferens, part of the male reproductive system, is controlled by a somewhat autonomous network of nervous connections. I suggest that in such tissues and organs we can see vestiges of a critical stage in the evolution of organisms, when primitive organs emerged which were self-regulating, capable of both function and the ability to control this function through reproducible patterns of activity in excitable cells. This stage was transcended only when a more centralized and more specialized nervous system emerged that gradually superseded the local form of control.

What about our own level of existence, the mental level? The scheme of transcendence I am developing here predicts that there should be, or later will be, a similar distinction between holons storing information in a reproducible form and holons exhibiting functional activity. Given that our level of existence has not completed its evolution, we would not expect these holons to be fully emerged, but surely they are beginning to emerge, on the one hand, in the cumulative knowledge of modern societies--in universities, libraries, and other centers of learning--and on the other, by technology, in all its forms. I further suggest that the hybrid holon necessary to complete the transition to a new level of existence--a holon that combines knowledge with technology--is the computer culture, including not only computer hardware and software, but the human beings who use it. This culture has the potential, for the first time in human history--i.e., in the evolution of our level--to combine reproducible information and technological production in a single type of organization.

Conclusions

I have shown how a broader, more generalized version of Darwinism, one retaining the key concepts of random variation and natural selection but applying them with different meanings on multiple levels of existence, has the potential to account for a much wider variety of evolutionary processes than has usually been assumed. One of these processes, usually called cultural evolution (Cavalli-Sforza and Feldman, 1981) has for some time been recognized by most evolutionists, but has usually been considered to be ultimately dependent on biological or genetic evolution. That is, the emergence of new cultural artifacts or memes selects certain genes, which in turn firmly establish the memes in a process of co-evolution.

As Dennett (1995) has pointed out, however, there is nothing in Darwinism that implies selection must be restricted to genes. Anything that can reproduce itself can become a unit of Darwinist selection if, in Dawkins' words, its reproduction exhibits fidelity, fecundity and longevity (1976). Blackmore (1999) argues not only that memes can evolve independently of genes, but that our large brain, use of language and other characteristically human features may have evolved specifically because they enhanced the spread of certain memes, rather than of genes.

The holarchical model I have adopted (Smith, 1999a) not only allows us to integrate cultural evolution into a broader theory that with biological evolution, but identifies several other evolutionary processes which are also fundamentally Darwinian in their character, even though genes are not the unit of selection.. A major benefit of such a unification is that it allows us to develop and test theories on one level of existence where we have evidence, then apply them to other levels where we don't. Thus our extensive familarity with the evolution of human social organizations has led to the idea of cultural evolution; this idea then has application to the evolution of cells into organisms, for which there is no fossil record. Conversely, to the extent that we can understand the evolution of earlier levels of existence, such as the biological or the mental, we may be able to some extent to predict how the evolution of a postulated higher level of existence may proceed.

It remains to be seen, of course, to what extent even very general Darwinian processes can account for evolution. While clearly these processes can create a great deal of diversification among social as well as fundamental holons, one could argue that transformative and transcendent processes, though greatly aided by this diversification, still involve another kind of change. Clearly, too, Darwinism can say nothing about the beginnings of existence; it has to have something to work with. I believe, though, that the broad theory of random variation and natural selection described here is a useful framework into which many other descriptions of evolutionary processes may ultimately be incorporated.

Notes

1. Taylor (1983)

2. Quoted in Allen and Starr (1982), p. 47

3. Lima-de-Faria (1988), p. 18.

4. A somewhat similar view of evolution was provided by Casyani (1980).

5. There are some significant exceptions to this rule, of course, particularly among insects.

6. Quoted in Capra, 1996, p. 287. Maturana does not like to define communication in terms of information, but as noted, I believe the one strongly implies the other.

7. Sexual reproduction, of course, requires an interaction between two organisms, or between two cells. Strictly speaking, however, this interaction is a communication process. Reproduction does not actually begin until a cell starts dividing. And while the process of cell division involves interactions among many different kinds of holons, the unit of reproduction, the cell, does not interact with any other holons.

8. If the cell had two copies of every gene, like a modern somatic cell in any organism, then the mutation would be passed along to only one of its two immediate descendants. The latter, however, would then begin a new line in which every cell contained two copies of the mutated gene.

9. I should emphasize that this is not group selection as evolutionary biologists normally mean it (Ridley, 1996). Groups are conventionally defined as populations distinct in space and time. As I use the term here, a group can be a few individuals within a much larger population, and the composition of this group may constantly change. However, the overall effect of the process is to reproduce the entire group, that is, to extend a characteristic set of relationships to the entire population.

10. Quoted in Capra (1996), p. 212.

11. This is the idea, of course, for which Chomsky (1985) is best known. The point I'm making here, however, does not depend on the truth of Chomsky's claim. The point is simply that there is some potential, some deep structure, in the brain that enables us to learn language. Regardless of whether this potential is in the form of rules of grammar or syntax, or something even more general, there is no question that it's universal in our species. Experiments with other primates make it quite clear that no amount of cultural exposure can transmit language as we use it to other species (Gill, 1997)

12. It's well recognized that many of the molecules that cells use to communicate with one another are homophilic--that is, they bind to other molecules of identical structure (Edelman, 1984). So if a group of cells each contain the same homophilic molecule(s), they can associate with one another. It's also known that such surface interactions can alter the expression of specific genes in the interacting cells. It has not been shown, to my knowledge, that the genes so affected may code for the same molecules interacting on the cell surface, but this is certainly a reasonable hypothesis.

13. In evolution of this kind at either level, there is reproduction of a social holon, so either this holon or the fundamental holons it contains may be the unit of selection. This therefore constitutes an exception to the rule that social holons don't reproduce. The exception occurs during the evolution of a higher level, before the new fundamental holon has emerged, and the social holons exist autonomously. In this case, however, no informational holon is required, because social holons retain their unique organization (the third distinction between social and fundamental holons I mentioned). Social holons are formed from relatively simple hetarchical associations of one kind of fundamental holon, or of one kind of lower social holon. Thus they can reproduce simply through the reproduction of these associations. In a fundamental holon such as a cell, the organization of lower holons is much more complex, involving vertical as well as hetarchical associations, and of many different kinds.

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