The Dimensions of Experience: A Natural History of Consciousness

By Andrew P. Smith

This book is an evolutionary history of life on earth. Its focus is not the evolution of the structural/functional adaptations found in any biology textbook, though these are necessarily discussed in a general way. Its primarily concerned with consciousness, with what the organism experiences.

Just how far back into evolutionary history consciousness extends, of course, is a highly controversial issue, and one which we will probably never resolve with certainty. We know we are conscious, and most people would probably extend consciousness to other mammals, but when it comes to lower vertebrates, let alone invertebrates, there is no consensus. This book takes a what if approach. What if all forms of existence were conscious to some extent, a view known as panpsychism or panexperientialism? Based on those aspects of their function and behavior that we can actually observe and measure, what can we say about what this consciousness is like? The resulting story is one in which consciousness becomes increasingly more complex over evolutionary history, yet is based on facts of animal behavior that any reader, regardless of personal views on consciousness, can accept.

In order to simply a vast amount of scientific literature, the book focuses on two general properties of consciousness and its behavioral manifestations: the experience of an outer world embedded in space and time; and that of an inner self that is defined by its relationship to other organisms. Two key claims made are that 1) dimensions of externally-perceived space and time have emerged more or less one at a time over the course of evolutionary history; and 2) the number of spatial/temporal dimensions experienced by any organism in the outer world is closely related to experienced inner dimensions in its relationships with other organisms.

For example, the simplest invertebrate organisms experience one dimension of space, in the form of intensity discriminations made of simple stimuli such as light, touch and chemical substances. Closely correlated with this one-dimensional experience of the outer world is the ability to make simple self-other discriminations, in which the organism in effect distinguishes itself one-dimensionally from the outer world. Somewhat more evolved invertebrates, such as arthropods, experience two dimensions of space, their perception being largely limited to shapes, contrasts, and surfaces. They can also distinguish between two dimensions in their relationships with other organisms, as exhibited in the ability to discriminate such classes of other as male vs. female and kin vs. non-kin. The most highly evolved invertebrates, as well as all vertebrates, experience additional dimensions of space and/or time and make still finer discriminations among other organisms.

The evolutionary story is not confined to organisms, however. The book argues that the same kind of dimensional relationships exist on lower levels of existence. Thus there are atoms that recognize and interact with other atoms in various degrees of dimensions, and there are cells that recognize and interact with other cells in different numbers of dimensions. Again, the minimal claim being made is that the function and behavior of these lifeforms can be understood in terms of dimensions, while leaving it up to individual readers to decide whether this could reflect a similar dimensionality of consciousness.



Review by Kirkus Discoveries

A lucid, thought-provoking and wide-ranging metaphysical treatise by novelist, scientific researcher and Stanford Ph.D. Smith.

Heralded as the first complete history of consciousness ever written, The Dimensions of Experience covers an astonishin

• Language: English
• Publisher: Xlibris US
• Release date: Oct 30, 2008
• ISBN: 9781465315908

Andrew P. Smith

Andrew P. Smith has a Ph.D. in Neurosciences from Stanford University, and has carried out research in molecular biology, pharmacology and cancer as well as neuroscience. He is the author of about 60 scientific articles, and several book chapters. He is currently associated with California Pacific Medical Center Research Institute in San Francisco, California.

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Copyright © 2008 by Andrew P. Smith.

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Contents

PROLOGUE

1

2

3

4

5

6

7

8

9

10

11

Endnotes

REFERENCES

PROLOGUE

A major purpose of fiction is to protest against the restraints of reality, whatever they happen to be in any particular time and place. Recognizing that, we should not be surprised that Victorian England, supremely confident in its belief in logic, reason and an objectively ordered universe, produced two of history’s boldest and most original challengers to this worldview. The better known and more widely read of these authors is Charles Dodgson (better known as Lewis Carroll), whose Alice’s Adventures in Wonderland and Through the Looking Glass are children’s stories that expose in very adult fashion ambiguities in language, in social rules and in the universally shared assumptions underlying our perceptions of reality.

Edwin Abbott’s Flatland, though nowhere nearly as deftly written, as witty, or as entertaining as the Alice stories, is arguably more profound. Almost every novel that has ever been written, even including most of today’s cutting-edge science fiction, begins with the assumption that its characters live in a world of three-dimensional space.¹ This world is so universal and so familiar to us that it’s extraordinarily difficult to imagine how we could live in any other kind. Certainly the variety and richness of human experience that is the subject of any novel would be severely compromised in any world of fewer dimensions. Conversely, a world of greater than three dimensions would be so different from our own as to be literally inhuman.

But Abbott showed us how to imagine these alternate universes. His Flatland is a world of two-dimensions, like the surface of a sheet of paper, populated by creatures that are forever confined in both their physical existence and conscious experiences to this literal plane of existence. They go about their lives, moving from place to place, interacting with objects, communicating among themselves, all while being limited to events that, one might say, are forever on the horizon—neither above it nor below it. So when their plane of existence is invaded by a three-dimensional form from the world beyond them, which appears and disappears without observable cause, Abbott supposes it would be incomprehensible to the denizens of Flatland.

Abbott was said to have written his story as satire, in particular, as a biting criticism of Victorian social prejudices. But it created an enormous public as well as philosophical interest in the possible existence of a fourth dimension of space, which in effect was represented allegorically in the story as the third dimension. For Abbott’s important message, which has been taken up by contemporary authors such as Rudy Rucker (1984) and A.K. Dewdney (2000), was that the way a two-dimensional creature would (or would not) understand, or experience, phenomena in the third dimension should give us hints as to how we three-dimensional beings might think about phenomena in a fourth spatial dimension beyond our ordinary world.

Since Einstein, science has generally thought of the fourth dimension as time, rather than space, but the possibility of a fourth spatial dimension is still very much alive. In the early part of the twentieth century, it was shown that by adding a fourth dimension of space, Einstein’s equations for the gravitational field and Maxwell’s earlier equations for the electromagnetic field could be seen to be part of a deeper, more comprehensive set of equations. Known as the Kaluza-Klein theory, this formulation effectively unified two of the four fundamental forces of physics (Kaku 2006). Much more recently, the emergence and development of string theory postulates a universe of half a dozen or more dimensions of space than the three we are aware of. These extra dimensions, according to string theory, are so tiny in their extent that only the properties of subatomic particles can be directly affected by them. However, some physicists currently believe that the four-dimensional universe (including time) we are aware of actually exists within a larger higher-dimensional space, perhaps along with other four dimensional universes, known as branes, like our own (Greene 2001).

The lower dimensional worlds, in contrast, are considered to be purely hypothetical, with no direct relevance to reality. Even the most radical scientist does not claim that there is, or could be, a real Flatland. According to science, the three major dimensions of space are a condition of all existence, within which the entire evolutionary history of earth has played out.

The central theme of this book is that this conventional view is wrong, indeed, spectacularly so. It’s my claim that there are indeed other dimensional worlds all about us, and creatures that live within, and experience, these worlds. There are not only lifeforms that live in two dimensions, but others that live in one dimension, and even some that live in a world of half a dimension or in zero dimensions. There are also lifeforms that exist in more than one dimension of time.

Is this some weird theory about creatures undiscovered by science, beyond the power of current technology to observe and record? No, the creatures that live in these other-dimensional worlds are very familiar to all of us. They include, for example, bacteria and amoebae, fungi and green plants, corals and jellyfish, starfish, worms, snails, crabs and ants, reptiles, birds and mammals. They also include Homo sapiens, who, I contend, accesses more dimensions than we commonly think we do.

This book is the story of these creatures. Or rather, it’s the story of their experience, of how they perceive and know the world they live in. It is no less than a natural history of consciousness, presented by those who have played its literally many-dimensional roles.

1

HOW HISTORY REPEATS ITSELF

Nothing seems to separate us so clearly from other forms of life on earth than our consciousness, yet perhaps nothing so connects us, either. Much of what we are conscious of—those hopes and dreams, as well as ideas, concepts, visions, the past, the future, the possible, the impossible, and most of all, our knowledge of being conscious—we completely share with no other animals on earth. Yet the simple fact that we are conscious, that we experience anything at all, is by no means unique to us. Some bold thinkers would argue that consciousness in this sense is universal.

The notion that everything, even inanimate matter, is conscious is known as panpsychism, from the Greek words for all minds¹. It’s a very old idea, going back to the dawn of human history. Almost all preliterate societies held an animistic view of their world, believing that everything in nature was alive and conscious (Campbell 1959; Gebser 1986). Panpsychism has also been an explicit part of the thinking of some of the world’s greatest philosophers, including Baruch Spinoza, Gottfried Leibniz, William James, Alfred North Whitehead and Sri Aurobindo. To most of us who live in modern, scientifically-based societies, however, panpsychism is likely to appear quaint, the kind of anthropomorphic fantasy that young children engage in, but hardly a view to be taken seriously by a rational adult. Almost all of us can accept that a dog is or could be conscious, and perhaps a bird, maybe even a snake or a fish. But what about a snail, a bacterium, a plant or a stone? Or a molecule or an atom? Surely not everything is conscious?

Recently, though, panpsychism has been making a rather surprising comeback. A significant and growing number of philosophers, and at least a few scientists, are beginning to consider the possibility very carefully (Chalmers 1996; Griffin 1998; Seager 1999a,b; de Quincey 2002a; Skrbina 2003; Laszlo 2007). The stakes in this debate are enormous. A panpsychist view radically revises our conventional notions of not just what is conscious, but of what consciousness is—that is, it has profound implications for our understanding of the relationship of consciousness to the physical universe, and how it has evolved along with this universe. In this book, I will explore these implications, and show that the panpsychist view provides a new way to tell the evolutionary story in which we are the latest characters.

Before we begin this story, however, we need to examine the rationale underlying it. It’s a fundamental limitation of ourselves—one that all the scientific advances of the past several centuries have been powerless to change—that we can never directly experience the consciousness of another person, let alone another form of life. This raises two serious issues at the outset. First, what is the evidence for panpsychism, that is, what grounds do we have for asserting that any other forms of life, let alone all other forms, are conscious? And second, even if we do believe other forms of life are conscious, how can we access this consciousness? That is, how can we say anything at all about how another form of life experiences itself and the world?

These are questions that could be—and have been—the central focus of entire books without definitive resolution. Here I will be content with addressing them in the remainder of this chapter. My goal is not to convince anyone that I have certain answers to either, but only that the case for both possibilities is reasonable enough to imagine a story, a natural history of consciousness. The rest of this book will be devoted to telling this story.

The Case for Panpsychism

Philosophers who hold a panpsychist view use two major arguments, one of them purely theoretical, or what Paul Edwards (1967) called genetic, the other based on experimental data, and which Edwards referred to as analogical². The genetic or philosophical argument has emerged in an effort to understand the relationship of consciousness to the material world. Traditionally, as any beginning philosophy student knows, there have been two ways of understanding this relationship. The dualistic view, which goes back to Descartes, says that matter, on the one hand, and mind or consciousness³, on the other are two entirely different sorts of ‘substances’ or phenomena. This view, which is probably still held by most people today who are not professional scientists or philosophers, seems to make obvious sense. After all, our mental or conscious experiences seem completely different from any properties of matter that we are familiar with. How can our simple sensory experiences of sight, sound, taste, etc., let alone more complex feelings and ideas, be explained by the interactions of physical matter?

The problem with the dualistic view, however, is that it fails to explain how mind and matter can interact, as they obviously do. The brain, which is composed of matter, somehow manifests consciousness. The brain is as necessary for this as the lungs are for breathing, or the stomach for digestion. Moreover, a wide range of studies has shown that specific areas of the brain are necessary for specific aspects of consciousness. These studies include direct electrical stimulation of the brain (Penfield and Rasmussen 1950), studies of individuals with localized lesions or injuries to the brain (Ramachandran 1998; Sacks 1999), and most recently, neuroimaging studies, in which the ongoing activity of neurons is measured in conscious subjects performing various tasks (Basar et al. 2006; Smits et al. 2006; Jackson and Crosson 2006; Gobbini and Haxby 2007; Coricelli et al. 2007). How can such a close relationship between mind and matter exist if the two are completely distinct phenomena?

The most common alternative to the dualistic view today is materialism⁴, which is held by almost all scientists and probably a majority of philosophers. In the materialistic view, consciousness is a property ultimately derivable from matter. Just as life—including the once mysterious phenomena of growth, development and reproduction—can now be understood to a great extent in terms of complex molecular interactions, so, in the view of materialists, can consciousness—in theory if not in practice.⁵ In support of this view, they note the obvious interactions between mind and matter that pose such a problem for dualism—interactions which science in the past several decades has illuminated and characterized in progressively more compelling detail.

The weakness in the materialistic argument, though, is that none of the known properties of matter seems capable of giving rise to consciousness. Not only has no materialist been able to provide a coherent theory of how consciousness might emerge from the properties of the brain; no one can even really conceive of how to begin such a project. Whenever a materialist comes along claiming to have such a theory, it always turns out that he or she is ignoring the most essential features of consciousness, not so much explaining them as explaining them away. At least that is the way it appears to their numerous critics.

This mind/matter argument has been raging for a long time, and many subtle twists to both the dualistic and the materialistic positions have been proposed. In an effort to escape this dilemma entirely, however, some philosophers have recently suggested a third possibility. Consciousness, in this view, is neither separate from matter, as the dualists claim, nor emergent from it in the materialist view, but is an intrinsic property of it. In this view, known as property dualism, the existence of consciousness is a fundamental aspect of matter, and its relationship to matter thus requires no further explanation (Chalmers 1996; Griffin 1998; deQuincey 2002a). That is, just as no physicist attempts to explain ‘why’ matter has mass or charge, because these are assumed to be part of what matter is, so, the property dualists claim, we should not ask why it could have consciousness.

Ironically, this argument has been aided to some extent by that traditionally most materialist of all scientific disciplines, physics. As I will discuss later in this book, quantum phenomena indicate an inherent indeterminism in the universe, suggesting to some that mental processes may function to determine physical ones (Lockwood 1991; Goswami 1993; Hameroff and Penrose 1996; Seager 1999a). Indeed, most scientists who are now at least sympathetic to the panpsychist view are probably well versed in quantum physics.

In any case, if consciousness is an inherent property of matter, it follows that all matter—not simply that in the brains of humans and other animals, but even inanimate matter—is to some degree or in some sense conscious. This conclusion obviously has very radical implications for our scientific worldview. To be a panpsychist does not mean that one necessarily believes that trees or rocks or lakes think or have feelings; one does not have to adopt the magical view of life our ancestors held. But panpsychism does insist that consciousness, or experience of some sort, was a property of the universe from its very beginning, billions of years ago. So the consciousness that we humans know and enjoy today, far from being a completely new evolutionary advance, might better be viewed as just the latest development in a process that started when the physical world was born. Just as the very atoms that compose our bodies and brains go back in time billions of years, so does something essential to our ability to experience the world.

The genetic argument—which, to repeat, has emerged as an attempt to reconcile the apparent inability of either dualism or materialism to provide a coherent account of the mind/matter relationship—thus forms one major pillar in support of extending consciousness far beyond our own species (Nagel 1979; Lockwood 1989; Chalmers 1996; Griffin 1998; Sprigge 1999; Seager 1999a,b; deQuincey 2002a). Not all philosophers, by any means, accept or even respect this argument. Many believe it’s ludicrous, not even worth debating. But there is a second argument for a broader view of consciousness, less sweeping and profound in its conclusions, but also more solidly supported by experimental evidence. This is being provided by studies in the growing field of animal intelligence. As the relationship of brain to mind has become of much wider scientific interest in the past few decades, some researchers have developed new methods for identifying and characterizing the intelligence of lower forms of life.

Traditionally, our knowledge of animal intelligence has come from observations in the field. While these still form a valuable and necessary part of this project, our insights into what may actually be occurring within another animal’s mind have grown more powerful through the use of controlled experiments. The subjects of such studies include not simply non-human primates like chimpanzees, and higher vertebrates such as mice and rats and birds, but lower vertebrates like fish, and invertebrates such as insects (Hauser 2000; Griffin 2001; Bekoff et al. 2002). There is even a substantial body of research on behavior of single cell organisms (Koshland 1974; Csaba et al. 1984; Nakagaki 2001; Queller et al. 2003; West et al 2006). Examples of the kinds of questions being asked in these studies include:

• What kind of stimuli can a particular organism recognize and respond to?

• Can it communicate such information to other members of its own species?

• Can it recognize, or distinguish among, different members of its own species?

• Can it remember past events?

• Can it learn new forms of behavior?

• Can it form internal maps of the external environment, for use in guiding its movements?

• Can it count?

• Does it carry around images of objects, or other organisms, even when the latter are not in its immediate presence?

• Can it recognize itself in a mirror?

While the problem of not being able to experience what another organism experiences remains apparently insuperable to science, these studies have made it clear that many fairly complex mental phenomena or capabilities exist in a wide variety of species. Many organisms are capable of performing tasks which, at least in our own human experience, require or are least are greatly facilitated by some conscious experience of the world.⁶ At the very least, these studies justify the conclusion that a great many forms of life could be conscious.

Also making a major contribution to views of animal consciousness is the field of biosemiotics. Dating back to the writing of the American philosopher Charles Sanders Peirce (1931-1966), and strongly influenced by ethologist Jacob von Uexkull (1934), researchers in biosemiotics argue that just as humans communicate through signs—specific forms of behavior that have shared meanings among all members of a society or population—so do other forms of life. This is now widely recognized with regard to higher mammals, but more controversially, many biosemioticists extend this principle down to more primitive organisms, and even to cells and molecules (Florkin 1974; Anderson et al. 1984; Hoffmeyer and Emmeche 1991; Kawade 1996; Kull 2000). I will discuss biosemiotics in a little more detail much later in this book, but for now I just note that the major thrust of his area of research is towards lowering the threshold at which consciousness is understood to have emerged in evolution, and thus many in the field are sympathetic to some form of panpsychism.

The Relationship between Organization

and Experience

In the final chapter of this book, I will revisit the issue of panpsychism, addressing some of the commonest objections to it in more detail. For now, though, I’m regarding it as a working hypothesis that consciousness did not emerge with our species, but has been around in some sense from the beginning of the universe—that all forms of existence are to some extent conscious. Even if this is not the case—and I’m well aware that this is a minority, perhaps fringe view even among philosophers, let alone scientists—I want to emphasize that the truth of this assumption is not essential to the value of the evolutionary story I will tell. As just noted, we generally infer consciousness from certain kinds of behavior, and as we will see shortly, it’s possible to describe different kinds of consciousness in terms that apply equally well to this behavior. Thus, those who dismiss the possibility of panpsychism, or even an extended range of conscious experience in the animal kingdom, can simply substitute in what follows, for terms such as consciousness and experience, more empirically supported concepts such as function or behavior. Indeed, I will use both sets of terms more or less interchangeably in this book. My rationale for doing this will become clearer as we go along.

That being said, if we do take the panpsychist view seriously, we must adopt a new view of evolution on earth. It’s not simply the process by which new structural or functional forms of existence have emerged, but also one by which new conscious or experiential forms have developed.⁷ Evolution becomes a story of how matter and life on earth have become increasingly more conscious.

The purpose of this book is to tell this story. While the evolutionary history of life on earth is well known, at least in its general outlines, this history has almost always been described purely in terms of empirically observable features—including both anatomical structures and behavior. A complete history of experience, of consciousness, to my knowledge, has never been written. Several evolutionary accounts have been written by authors highly sympathetic to a panpsychist view (Teilhard de Chardin 1959; Steiner 1966; Wilber 1981; Aurobindo 1985; Gebser 1986; Gidley 2007), but their discussions of consciousness have been largely limited to that of our own species. ⁸

This book attempts to go much further back in time, to as close to the beginning of life on earth as possible. The book asks, and attempts to answer, two fundamental questions. First, if all forms of existence are to some extent conscious, what is this consciousness like in each case? For example, what does a cell or a plant or an insect—as well as a bird or a dog or a chimpanzee—experience? And second, if our human consciousness is the result of a long evolutionary history of consciousness, how did each stage or level of consciousness make the transition to the next? What are the processes by which lower forms of consciousness evolved to higher forms?

To many readers, this might appear to be a quixotic venture. As noted earlier, we can never put ourselves in the position of another form of life, so how can we pretend to know what, if anything, it experiences? Even granting the premise that lower forms of life are conscious, how can we even be certain that we are capable of understanding what their experiences, presumably so very different from our own, are like?

The multilevel brain. One answer to this objection is to remind ourselves that we can never put ourselves in the position of another person, either. We assume not only that other people are conscious, but that their consciousness is very much like our own, because they are so like us in other ways—in the manner in which they move, speak, express themselves and communicate to us. In somewhat the same way, students of animal intelligence look within the behavior of their subjects for clues to what these other species might be experiencing. While it’s obviously a major handicap in such studies that other animals have a very limited ability to communicate directly with us, this problem to some extent may be overcome by the intentional design of experimental situations that increase the likelihood that the animal will express itself in a way that we can interpret. From the answers to such questions, we can begin to build an understanding of what an animal could—and just as important could not—experience in a conscious manner.

Another very important, and I believe almost completely overlooked, tool in this endeavor is our own ability to experience multiple states of consciousness. When we describe ourselves as conscious, we generally are referring to the state we exist in during our waking hours. But in addition to this conscious state, we are of course able to access several others, such as when we sleep or dream, are under the influence of certain kinds of drugs, or follow special meditative techniques (Masters and Johnson 1966; Tart 1972; Austin 1998). An important theme that this book will explore is that some of these alternative states of consciousness may have important features in common with those experienced by other organisms, and thus provide us with a more direct path to understanding the consciousness of these creatures.

While this is certainly a novel way of studying animal consciousness⁹, its underlying rationale should not really come as a surprise. Scientists recognize that the human brain evolved not by discarding the evolutionary adaptations of earlier organisms, but rather by adding to them. This is why our brain is often referred to as triune in its organization, meaning that in addition to the cognitive or thinking portion represented by the cerebral cortex, we also possess a limbic or emotional brain, much like that of other vertebrates, and a still earlier set of structures controlling posture and gross bodily movements, commonly called the reptilian brain (MacLean 1973). In fact, the triune model can, and should be, expanded in its concept to still earlier evolutionary forms, such as the autonomic nervous system and the spinal cord. Each one of these portions of our complete human nervous system functions, in certain types of organisms, as an entire brain. So we clearly carry around within us literally hundreds of millions of years of evolution of the nervous system. It would seem that in principle we have the ability to experience ourselves and our world through each of these different levels, and in this manner commune very profoundly with the worldview of other organisms.

Of course, there are limits to what we can directly experience, while still maintaining our uniquely human capacity to describe it in a manner capable of communication to others. After all, we are ultimately composed of atoms and molecules, so in principle we might have access to the experience of these forms of life, too, but could we really expect to be able to access this experience in a meaningful way? Could we descend to the level of a molecule, experience its world, then regain our more usual state of consciousness and report our findings to others? Highly unlikely. To probe consciousness at depths so far from our ordinary existence, we surely need some other approach, one that will have to be based not on experimentation, but on theory. We need, it seems to me, a way of evaluating consciousness based on other aspects of the lifeform that are accessible to us. In other words, we need a theory that describes, for any form of existence, the relationship between its observable, structural and functional features, and its experience. The assumption underlying such a theory is that if we know what any form of existence looks like we can immediately know something about what it experiences.

If this sounds like a considerable stretch—if such a theory appears to have the magical property of revealing what is invisible from what is visible—consider that this has in fact been the goal of the field of neuroscience for the past half century. Most scientists believe that human consciousness emerges in some manner from the organization of the human brain—the way in which its neurons are connected to each other—and are trying to define just how this comes about. Furthermore, according to the school of thought called functionalism—a view held by many, though by no means all, modern philosophers—organization is the critical word here. In the functionalist view, any form of existence—artificial as well as natural—will manifest consciousness if it has the proper organization among its components (Dennett and Hofstadter 1981; Dennett 1991; Chalmers 1996; Hofstadter 2007). No need to use neurons. Silicon chips will do just fine—or even tin cans, for that matter—if there are enough of them, and if they are connected in the proper way.

Functionalism has been subjected to some fairly severe criticisms (Searle 1980, 1992; Chalmers 1996; Griffin 1998; Seager 1999a), and the idea certainly remains unproven. Indeed, as I noted earlier, it is just the failure of this kind of theory to convince its critics that has fueled the interest in property dualism. It’s not necessary to be a functionalist, however, nor even to accept the prevailing scientific premise that consciousness emerges from the activity and the organization of the brain, to see that there is a close relationship of some kind between the two.

Philosopher John Searle, no friend of functionalism, argues that we know animals like dogs are conscious not only from their behavior, but because of similarities of certain parts of their brain to ours (Searle 1992; see also Butler 2008). Conversely, though, dogs, and other animals are less conscious than we are because of differences in the structures of our brains. If we compare the brains of humans and other organisms, vertebrate and invertebrate, we see immediately that evolutionary development closely correlates with what we can call complexity. What I mean by complexity will become clearer as we go along, but for now, it should be obvious that our brain is more complex than that of a dog, the latter’s brain is more complex than that of a fish, which in turn is more complex than that of an insect. These relationships in fact follow directly from the triune or extended triune model of the brain that I mentioned earlier; each brain contains the basic structures of the preceding brain, but integrates them with new, additional structures. If we accept the premise that consciousness follows the same pattern—that humans are more conscious than dogs, which are followed by fish and then insects—we see evidence for a close relationship between consciousness and complexity. The more complex an organism’s brain, the more conscious it is. I believe almost all scientists would accept this conclusion as a general rule, though many might quibble over some specific comparisons.

Can we extend this relationship further? Can we claim that for living things that have no brains—plants, for example, or single-celled organisms—there is also a relationship between consciousness and complexity of organization? Can we even make this argument for non-living things such as molecules or atoms? If we adopt the panpsychist premise, it seems to me that we not only can, but must. If consciousness of some sort is a fundamental property of matter, we would expect that as matter becomes more complex, so would consciousness. This view explicitly formed the basis for Teilhard de Chardin’s view of the evolution of consciousness (Teilhard de Chardin 1959).

Though Teilhard de Chardin’s panpsychist vision, involving a goal-directed evolution, is at odds with modern neo-Darwinist theory, the essential notion that consciousness and material complexity have evolved in parallel could be quite compatible with it. The key question then becomes, what exactly is the relationship of consciousness to matter? How does complexity in one manifest itself as complexity in the other?

Envisioning dimensions. It seems to me that the simplest way to approach the relationship between organizational complexity and consciousness is in terms of dimensions. We experience three dimensions of space and a single dimension of time (though I will suggest later that we actually access two dimensions of time). This raises the question of whether these dimensions of experience might have evolved separately, a notion that has been explored by others as well (see Box 1).¹⁰

Our experience of space and time is so fundamental and familiar to us that it might be thought that any conscious organism would likewise experience the world in this manner; but in fact numerous studies, which I will discuss in detail in this book, indicate that this is not the case. The behavior of the very simplest organisms demonstrates they make little distinction between themselves and their environment, suggesting that to the extent they are conscious at all, they experience no dimensions at all of either space or time. There are other invertebrates, still quite simple, that exhibit the ability to discriminate simple intensities of stimuli, a behavior that requires experience of only a single dimension of space, and very little if any experience of time. Similarly, we can identify more advanced invertebrates that recognize two dimensions of space, while a few invertebrates, and all the vertebrates, recognize three dimensions of space. Only with the higher vertebrates does the experience of time as an extended dimension emerge.

So a central claim I will defend in this book is that conscious experience of the world evolved in fairly discrete stages, each characterized by a certain degree of dimensionality, and that each stage was associated with a certain degree of complexity. Indeed, as is often the case with evolutionary stages, we can see all of them played out within our own species. Consider vision, one of our most highly developed means of experiencing the world. Human vision begins with light energy striking the retina. At this stage, our experience of the world (if we were aware of it) is largely one-dimensional. The light sensitive cells in the retina, rods and cones, are sensitive to intensity of light, and that is the information they send to the brain.

It is only later—in an evolutionarily higher part of the nervous system, the visual cortex—that this information about light intensity becomes transformed into such experience as the orientation of lines or edges. This kind of information, I will discuss later, is a key feature of two-dimensional experience, the ability to recognize and distinguish surfaces. Further processing in the visual cortex, requiring still more complex portions of the nervous system, results in our ability to experience three dimensions of space. Some experience of time is also elaborated in the visual cortex, because cells in certain parts of this brain region are sensitive to motion, but our highly developed experience of time—allowing us, for example, to form enduring mental representations of objects in the environment—requires further processing in still more complex regions of the brain, areas outside of the visual cortex that relatively few other organisms have.

The example of visual experience not only illustrates how our multi-dimensional view of the world is built up through information processing in increasingly more complex neural structures, but illuminates a key relationship of these structures to each other: they are hierarchical. Hierarchy is one of those terms that everyone uses, but not in exactly the same way. I will define it a little more carefully later in this chapter, but for now we can just say that a higher hierarchical stage of the nervous system contains, and integrates, several or more lower stages. For example, cells in the V1 region of the visual cortex, many of which respond to edges, receive (indirectly, through intervening neurons in the visual pathway) inputs from a small group of cells in the retina (Hubel and Wiesel 1959, 1962; Chapman et al. 1991). A single cell in V1 thus has access to all of the information contained in an entire group of cells at the level of the retina. Likewise, it is now believed that cells in hierarchically higher areas of the visual cortex, as well as other areas that obtain information from the visual cortex, elaborate three dimensional experience by integrating informational inputs from many of the edge cells (Stringer and Rolls 2002; Tsutsui et al. 2002; Sereno et al. 2002; Welchman et al 2005; Grossberg et al. 2007). Regions of the brain where our extended sense of time emerges lie outside the visual system, but receive inputs from large numbers of cells that are involved in processing of spatial information (Baker et al. 2001; Baird et al. 2002).

This understanding of the visual system thus suggests that our experience of dimensions of space and time is related to hierarchical processing of information by the nervous system. At each new hierarchical stage, experience becomes more complex, and at some stages, a literally new dimension of space or time is experienced. Moreover, the complete hierarchy has been built up gradually, through evolutionary processes. As we will see later, there are very simple invertebrates whose visual experience is limited to basically the level of the retina in our own system. There are somewhat more complex invertebrates whose visual processing extends just to the level of the detection of orientation of lines or edges. And so on.

Still further, this relationship can also be extended to lower levels of existence, such as cells and molecules. Though cells and molecules of course do not have nervous systems, they do exist in hierarchical organizations, as I will discuss further shortly, and higher hierarchical stages process information that flows to them from lower stages, just as is the case in nervous systems. This suggests that if we are going to hypothesize that these forms of existence have some conscious experience, it will also be correlated with hierarchical complexity.

Again, the visual system is instructive. When photons of light enter the eye and fall on the retina, they are absorbed by certain atoms within a small molecule known as retinal. This absorbed energy induces the retinal molecule to change its shape, and this change is transmitted to a much larger molecule, the protein rhodopsin, which also changes its shape. This in turn results in a sequence of further chemical changes that culminate with the flow of ions into the rod or cone cell. This generates an electrical signal that will be transmitted to the brain.

The hierarchy here consists of atoms; the small molecule retinal, which is composed of about fifty atoms; the much larger molecule rhodopsin, which is composed of retinal and several hundred amino acids, which are also relatively small molecules; a signal transduction pathway, which contains rhodopsin and several other proteins; and the cell that contains all of these components. Though this information processing pathway is much simpler than that of cells in the brain, and its hierarchical organization differs in some other ways as well, each stage integrates information from multiple members of the lower stage. Moreover, as I will show later, the behavior of successively higher stages can be characterized in terms of successively higher dimensions.

With this general introduction to the relationship between hierarchical complexity and complexity of experience, I will now turn to a more detailed discussion of hierarchical relationships in nature. This discussion will focus on structural and functional hierarchies. Later, I will return to the subject of consciousness, describing in more detail how the experience of dimensions is related to the structural organization of the experiencing lifeform.

Natural Dimensions

Science now recognizes that hierarchical organization is found throughout nature, from molecules to cells to organisms to societies (Mayr 1982; Allen and Starr 1982; Salthe 1987; Becker and Deamer 1991; Raff 1996; Valentine and May 1996; Depew and Weber 1997; Barlow 1998; McShea 2001; Changizi 2001b,c; McShea and Changizi 2003; Valentine 2003). What I want to do here is examine the concept in a little more detail, and show how it is closely related to the idea of dimensions.

Like complexity, with which it is fact very closely related, hierarchy is defined somewhat differently by different investigators. Theorist Mark Changizi, who has elucidated some general laws that apply to many hierarchies, argues that the defining feature of hierarchical systems is that they are combinatorial, which he describes in this way:

a system is combinatorial when the number of component types scales disproportionately slowly compared to the number of expressions.¹⁷

By expressions is basically meant the components of a higher hierarchical level. So a system is hierarchical by this definition if the members or components of one level can combine to create a larger number of members or components on a higher level. Human language is often provided as an example. A few dozen letters can combine into tens of thousands of words, which in turn can combine into perhaps millions of sentences, and still greater numbers of paragraphs and other textual units.

While I will not necessarily hold myself strictly to this definition of hierarchy, it applies to many of the hierarchical systems that I will discuss in the book. If we look within cells, we can see a series of levels that are hierarchical by this definition, beginning with atoms, the classical building blocks of life (Table 1A).¹⁸ A relatively small number of different types of atoms—carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus—can combine to create a much larger number of small biomolecules, including amino acids, nucleotides and sugars. Twenty or so amino acids, in turn, can combine to create hundreds or thousands of peptide molecules, in which these amino acids are linked end to end. A few different peptide molecules can combine to form a larger number of different protein molecules.

TABLE 1

THE DIMENSIONS OF EXISTENCE

A) Dimensions of the Physical Level

B) Dimensions of the Biological Level

C) Dimensions of the Behavioral Level

Hierarchical organization thus combines a few units or components at one level into a larger number of units or components at a higher level. Moreover, in nature, many hierarchies are also holarchies (see Box 2). In holarchies, a single unit or component at one level includes several, generally a large number of, units or components on the immediately lower level. An amino acid contains one hundred or more atoms. A peptide contains dozens or hundreds of amino acids. A complex protein can contain a dozen or more peptides. Such components are called holons, a term referring to the fact that they are simultaneously both wholes and parts (Koestler 1969). Thus an amino acid is a whole, composed of many atoms, but it’s also a part, contained within a peptide. A peptide is composed of many amino acids, but in turn is contained within a protein.

The key feature of holons relevant to our present discussion is that their relationships with each other approximate those of dimensions. Consider an atom. In the scientific view, an atom is a three-dimensional form of existence. However, it is so very small, compared to the world with which we are ordinarily familiar, that we might regard it as approximating a point, a zero-dimensional body. From this vantage, small molecules such as amino acids, which are composed of one hundred or more atoms, are one-dimensional bodies. Likewise, peptides, which are composed of dozens or hundreds of amino acids, are one-dimensional relative to an individual amino acid, and two-dimensional relative to an atom. Similarly, complex proteins are three-dimensional with respect to atoms.

Holons thus have a relationship to each other that I refer to as natural dimensions. They are not exactly like mathematical dimensions. The characteristic feature of mathematical dimensions is that they have a relationship of infinity to each other. A line, a one-dimensional figure, contains an infinite number of zero-dimensional points. A plane, a two-dimensional figure, contains an infinite number of lines. A three-dimensional cube or sphere contains an infinite number of planes.

Holarchical stages have a relationship to each other that is not infinity, but which does approach it; the relationship is of many to one. There are many atoms in what I call a one-dimensional molecule, but not an infinite number. There are many, but not an infinite number of, one-dimensional molecules in a two-dimensional molecule; there are many two-dimensional molecules in a three-dimensional molecule.

Another important difference between mathematical and natural dimensions is that in the latter, the relationship is not (necessarily) one of point to line to plane to cube or sphere. When I claim that certain molecules are one-dimensional with respect to their component atoms, I don’t mean that their atoms are arranged like beads in a necklace (though sometimes in fact they are).¹⁹ I mean that the atom, the zero-dimensional body, is the fundamental unit that composes the molecule. There is ordinarily no stable stage or state between the one and the other. In nature, as Francis Crick (1966) pointed out, we generally go from atoms to molecules of a certain minimum size.²⁰ Likewise, what I call a two-dimensional molecule does not necessarily have a planar appearance. It’s two-dimensional because it contains a large group of one-dimensional molecules, which in turn contains a group of zero-dimensional atoms. And similarly with the third dimension.

We could therefore say that mathematical dimensions are an abstract ideal of what is approximated by actual dimensions as we find them in natural holarchies. Yet there is a close relationship between them, because as we will see, mathematical dimensions of a particular degree are strongly correlated with natural dimensions of the same degree. I have already hinted at this in the earlier discussion of the visual system, and many more examples will follow. So, for example, when I refer to a complex protein as a three dimensional molecule, I mean that it is three hierarchical stages higher than an atom, but also that it has features or properties that involve three dimensions of space.

So far I have considered only dimensions of space, but natural holarchies may also incorporate dimensions of time. Consider a complex protein, which I have provided as an example of a three-dimensional molecule. Many proteins exist not only in space, but also in time. That is to say, in order to understand their function, we not only have to take into account their spatial dimensions—their particular shape or conformation—but also that these dimensions can change during time.

For example, an enzyme molecule catalyzes the conversion of some substance, called a substrate (usually a smaller, one-dimensional molecule) to another substance (called the product) by changing its shape in a certain way. To understand the enzyme molecule, or to perceive its complete existence, we must therefore observe it not only in space, but also over a certain period of time. During this period of time, which is known as the enzyme’s catalytic cycle, the enzyme molecule will typically change its conformation from one shape which allows it to interact with its substrate to a second, different shape that allows it to release its newly formed product. An enzyme molecule seen over this entire period of time is therefore a four-dimensional body with respect to its atoms. It has three spatial dimensions and one temporal dimension. This contrasts sharply with its component atoms or amino acids, most of which do not exist, in a functional sense, in these additional spatial and temporal dimensions.²¹

Temporal holarchies, like spatial ones, may follow Changizi’s combinatorial rule, in which a small number of components at one level have the potential to combine into a larger number at a higher level. Each of the multiple peptides or subunits typically found in most enzymes may exist in two or more different conformations, which may combine to form multiple activity states (Monod et al. 1963; Koshland et al. 1966; Changeux 1998). Moreover, other activity states of an enzyme may exist depending on such factors as whether it interacts with certain small molecules (known as regulators), gains or loses a molecular group such as phosphate at a specific site, or interacts with still other enzymes (Chock and Stadtman 1977; Johnson and Barford 1993). Living cells use such processes in order to adapt a single enzyme to multiple purposes at different times, but the point here is that such regulation transforms a single three dimensional protein into a four dimensional process composed of many different temporal states of that protein.

The limits of holarchy. To summarize the discussion so far, nature creates new forms of life by joining units, called holons, into more complex holons. Atoms form amino acids; amino acids form proteins; proteins form larger structures. Each new form of life may be considered higher or more complex than any of its individual holons. Again, without trying to define complexity precisely, I will just note that each new holon has emergent properties, ones not found in its component holons. Thus amino acids have properties not found in their individual atoms, peptides have properties not exhibited by individual amino acids, and so on. Examples of such properties will be provided later, when I discuss these forms of existence in more detail.

We might imagine that new holons could be created endlessly in this manner, by simply combining holons at one stage or dimension into ever larger groups. In nature, however, this process does not, and cannot, go on forever. It reaches a definite limit.

Why should this happen? The organization of holons as I have described them so far is relatively simple. Each is composed of a great number of similar holons of a lower dimension. Because all of these lower-order holons are similar, and because they are organized in a relatively simple manner, there are limits to what they can accomplish. In particular, holons of this kind can’t reproduce themselves. A molecule, for example, no matter how complex, generally can’t on its own divide and produce two identical copies of itself.²²

For reproduction to occur, a somewhat different kind of organization must emerge, one in which many different kind of holons are put together. In the evolution of molecules, this occurred with the emergence of the cell. Unlike an amino acid, which contains only atoms, or a protein, which contains only amino acids, a cell contains many different kinds of holons. In fact, it contains all the different kinds of molecular holons that are found in nature. In any cell, we find individual atoms; small molecules such as amino acids and nucleic acids; simple polymers such as proteins and DNA and RNA; and still more complex groupings of these holons.

The organization of a cell, on the one hand, and that of any molecule, however complex, on the other, represent two different kinds of hierarchy (see Box 2). As I noted earlier, holarchy is a special type of hierarchy in which members of higher stages include members of lower stages. Thus proteins include amino acids, and amino acids include atoms. Holarchy is exemplified by a series of Chinese boxes, each of which is nested within the next (see Fig. 1A). In addition to nested hierarchy or holarchy, however, hierarchy can also take a non-nested form, and this is characteristic of the cell. A cell is like a box which contains many separate boxes within itself (see Fig. 1B). Each of these boxes, itself, may be like a traditional Chinese box, with the one-within-the next form. So I refer to the cell’s organization as mixed hierarchical, meaning it contains both nested (holarchical) and non-nested hierarchical structures. ²³

image%201.jpg

Fig. 1. Nested and non-nested hierarchy. In nested hierarchy or holarchy (A), higher holons include the lower ones, like a series of Russian dolls. This organization is typical of social holons, such as molecules, tissues and human and animal societies. In non-nested hierarchy, holons exist outside of immediately higher holons. A fundamental holon such as a cell or organism has a structure consisting of both nested and non-nested hierarchy, as shown in (B). In this mixed hierarchical structure, nested holons of various sizes or stages exist outside of one another, but all are included within a higher holon.

Cells therefore represent a profound transition point in nature, in which one level of existence, which I simply call the physical, is completed, and a new one, the biological, begins. For this reason, I call cells fundamental holons, fundamental to a new level of life. I also refer to them as individual or autonomous holons, since many types of cells are capable of existing on their own, outside of higher stages consisting of many cells.²⁴ It’s their ability to reproduce that provides them with this autonomy. Atoms, though they do not reproduce, are also capable of existing outside of higher-order holons (carbon, oxygen, nitrogen, sodium and many other atoms can exist without being joined with other kinds of atoms into molecules), and so I also consider them as autonomous or fundamental.

In contrast, holons such as molecules I refer to as social or intermediate holons, since they are composed of groups of autonomous holons, and form intermediate stages within a single level of existence. They generally cannot exist outside of higher-order holons. Thus individual protein or nucleic acid molecules, for example, are not found outside of cells or organisms, except in the artificial conditions of the laboratory.

Because a cell is not purely holarchical in its organization, we can’t specify its relationship to its components in terms of natural dimensions. But since it begins a new level of existence, we can simply repeat the process we just went through with atoms and molecules. That is, we can begin by taking the cell as a zero-dimensional body or a point, just as we did with the atom before. While the cell is obviously not zero-dimensional with respect to its component atoms or molecules, it is zero-dimensional with respect to the new level which it is beginning. From this point of view, higher dimensional stages are exemplified by certain kinds of organizations of cells, including colonies of micro-organisms as well as various tissues within organisms (see Table 1B).

We can also identify multicellular holons that have an existence in time as well as in space, just as we saw was the case with certain kinds of molecules. A good example of this is found in the brain, where groups of highly connected neurons form networks. The neurons within such