Thursday, March 31, 2005

Consciousness - what we don't know about it

Well, that's most things. We don't know its nature. We don't know whether it can be explained by the physics that we know now. We don't don't know if only the brain is involved or if there is some other entity involved as well. We don't know whether it can occur only in living organisms or it can occur in some computer-like machine. We don't know to what extent processes similar to those in a computer are involved. We don't know if something in the brain besides neural connections is involved. We don't know just what animals it occurs in and to what extent. We don't know if it is a special case of some more general phenomenon.

All I can do is to exclude some possibilities, summarize some of what we do know and do a little bit of speculating about what we don't know.

What we know about consciousness comes from three sources. The first is introspection, our ability to perceive part of the workings of our mind. The second is communication with other conscious beings. The third is the observation of other conscious beings.

Introspection is incomplete. How often have you had a feeling that you could not explain the reason for, even to yourself? How often do people lie to themselves? It is possible that some sensory information bypasses the conscious mind e.g. pheromones if such things do have an effect on humans. Nevertheless your own consciousness is the only one that you can directly perceive. There is information available from introspection that is not available from other sources. In fact we only that other people are conscious by inferring from our experience of our own consciousness. We perceive our own consciousness. We observe that other human beings are entities similar to ourselves. We observe that they behave in similar ways to ourselves. They communicate their conscious states. From this we know that they are conscious. Our perception of our own consciousness is an essential part of this inference. It is what we compare the communications and observations to.

The problem is others cannot directly perceive our consciousness, only our communications and actions. Introspection is a poor candidate for scientific experimentation. We cannot check what others are doing inside their heads and so it is difficult to demonstrate ones introspections to others and to verify them. There is the danger of seeing in oneself what one wishes to see. Thus scientific methodology tends to restrict itself to those introspections that we can be sure that everyone shares. These are the ones that we can clearly communicate to another person. This tendency leads to the temptation to reject introspection altogether as being unscientific. This can lead to communication and observation being regarded as by themselves providing all the information about consciousness that can be found. In the name of objectivity the subjective is ignored even when the subjective is what is being studied.

But we have to somehow include our self-perceptions in any complete study of consciousness. It has to be studied from the inside as well as from the outside. Either by itself will provide an incomplete picture.

Communication includes both languages and systems of signals. A language has a syntax and a set of symbols. Symbols are signs which have a meaning attached to them by the users' choice. This can be and usually is a collective and tacit choice. The same word can have different meanings in different languages. The syntax is the set of rules by which the symbols are combined to convey concepts that cannot be conveyed by any single symbol. Signals are unchosen signs e.g. a growl or a smell or so-called body language. (Body language does not have a syntax or symbols and hence technically it is not a language even though it is a structured communication system.)

Much of our communication of emotions is through body language and audible signals. We have enough body language and audible signals in common with some other terrestrial vertebrates to be able to read their emotions to some extent. We can do this reasonably well with other mammals and to some extent with birds and at least some reptiles. We can be sure that they have at least some emotions and hence are conscious. We know that there is something in there.

We can teach a syntactic language to the great apes. We know from communication with them and from observing their behavior that they are self-aware like us. I know of no evidence of self-awareness in any other animals and think they are the only self-aware creatures other than ourselves.

Some vertebrates are the only entities other than ourselves that we know are conscious to some extent. We know that because there is some communication with them. Consciousness could be found in a wider variety of animals but we can't be certain because we can't communicate with them.

Since the senses of fish and amphibians are similar to our own it is quite likely that the subjective perception of sensory data is similar. Since the senses and behavior of cephalopods are similar to those of vertebrates it is quite plausible that their subjective world is similar. But then again maybe not. The brain has been rewired a lot as vertebrates evolved. For instance more of the brain is involved in vision in a mammal than a fish's optic lobes.

For other animals we only have their behavior to go on. I don't know of any completely convincing evidence of consciousness in any other animals. I would not be surprised if there is a rudimentary form of consciousness in amphibians, some fish and some cephalopods. I would be surprised if it occurred in any animals other than the ones that I have mentioned. While many arthropods have complicated behavior it is very stereotyped and I believe that consciousness does not help explain it. The behavior of animals other than chordates, arthropods and molluscs is simpler and can be explained without consciousness.

I believe that self-awareness is restricted to humans and great apes. I believe that emotion is restricted to mammals, birds and reptiles. I believe that subjective sensation, true awareness is restricted to vertebrates and cephalopods. To put it mildly these lists are tentative.

The main argument I can think of for rudimentary consciousness in animals other than vertebrates and cephalopods is an evolutionary one. Consciousness evolved with the elaboration of the nervous system. Could there be some precursor or rudimentary form in more primitive animals? The main argument against this is that there is no apparent benefit of consciousness in lower animals and nothing in their behavior that needs consciousness as an explanation.

Could a computer or some other non living system become conscious? We don't know. I believe that a computer as we know them cannot. All computers are Turing machines. They are all purpose symbol manipulators. They can carry out any algorithm with any symbol set and set of rules for manipulating them. But an algorithm is just the symbols, the rules and a set of actions using them. Any symbol can have any meaning that we give it. Thus the meaning of what is done is not part of an algorithm. The same algorithm can have different meanings. For example we could calculate the mean weight of ten fruit. The fruit could be apples or oranges. The algorithm involved is the same. The meaning of what a computer does is assigned to it by us - it is not a property of the algorithm or the computer.

This does not mean that computable processes are not part of what is going on. Turing machines could be components of the machinery of consciousness. However they might be taking a role that could also be take by something acting in a non computable manner - say something using some random quantum process.

The ability of the neurons of the brain to modify themselves might be involved. This is only a plausible speculation. If this is the case then the hardware and software of the brain might not be distinct concepts. We will have to look at things another way - even self-modifying programs are probably not similar enough to conscious processes to offer us much insight.

MRI and other new techniques can pinpoint what areas of the brain are active when particular mental processes are going on. This still does not tell us what is happening. Just what is the relationship between the observed neural activity and the mental processes?

The nerves of vertebrates are different from those of other animals. The axons (long nerve fibers) are encased in myelin sheaths formed by of a type of cell called a glial cell. These allow much faster transmission of nerve impulses than in the unmyelinated nerve fibers of most invertebrates. (The giant motor axons in cephalopods allow even faster transmission of nerve impulses.) Are the glial cells involved in consciousness in ways other than as impulse accelerators?

Contemplate the colour blue. This is the sensation that we get when light of a certain range of wavelengths hits the retina. If the pigments in the cones were different we would gain this sensation from a different range of wavelengths. What we perceive is some mental representation of light not light itself. Our perception of the colour blue is not something that exists in the world outside our skulls. So just what is it?

This suggests that perhaps our perception of space and time is a representation rather than the real thing. We can directly visualize only three spatial dimensions but can mathematically handle any number.

We perceive our subjective selves as some sort of entities. Perhaps this is an illusion - a subjective representation and there is no thing at the core of us that does the perceiving. Perhaps the real us is just a process in a structure. But we certainly feel like we are some sort of thing. This is the strongest argument that I know of for there being something other than just the brain involved in consciousness.

People are usually vague when they talk about a soul. Is it connected to life or to consciousness? Life is well enough understood for us to say there is no need for any non physical entity to be involved. One can make a case for the soul as the non physical core of consciousness. But it cannot be conscious by itself. What affects the brain affects the mind. If the brain is inactive you are not conscious.

If the soul exists and is the core of consciousness then how can it be in a fetus before the parts of the nervous system that are involved in consciousness are active. If it is not involved in life and it is not the core of consciousness then what difference does having one make?

Is consciousness an special example of something happening around us that we are not recognizing? Yet when it occurs all its instances are isolated. As far as we know we have no direct contact with any consciousness other than our own. We only known them by communicating with them and by their effects.

We are certainly looking at something the wrong way. I believe that we are at least two major scientific breakthroughs away from understanding consciousness. I believe that something is going on that current physics cannot explain. And even after the required physical insights have occurred we will need another breakthrough to allow them to explain subjective experience.

I think that consciousness is an indicator of a major gap in physics in the same way that evolution and uniformitarianism indicated a major gap in nineteenth century physics. I believe that it will take decades or even a century or two before we understand consciousness to the same extent that we understand life now . Scientific advances do take time.

Friday, March 18, 2005

Life and not life

There are phenomena that have some of the properties of life but are not what we think of as life. There are also phenomena which we talk of as being life which actually are not life itself. I want to compare these systems with living systems.

The obvious examples of the first are viruses and prions. I would describe these as life-like rather than alive. They replicate and mutate like life (at least viruses mutate). But they do not maintain themselves and are not self-contained. They hijack the systems of living organisms. They do not use their own systems to replicate themselves. They do not manufacture their own components.

The important example of the second is consciousness. It appears to be a life-dependent process but is not life. We only know of it in animals with complex nervous systems. All known examples are dependent on brain activity. Damage to the brain or disruption of its activity by drugs affects the mind.

We do not know what the physical basis of consciousness is. We do not know if it can be explained by the actions of a network of neurons or whether there are as yet unknown physical principles involved. Our knowledge about consciousness now is comparable to our knowledge about life before the discoveries of the 1950s and 1960s.

We do not know whether life is necessary for consciousness. Perhaps it could happen in some computer-like machine. (I say computer-like because I doubt that it can occur in computers as we know them.) Perhaps the brain's ability to modify itself is involved. In that case a conscious system would have to be life-like in some respects.

However we do know that consciousness is not necessary for life. A seaweed is alive but not conscious. A human being in a coma is still alive as an organism, not just as a collection of cells.

The trouble is that we have no word for consciousness as an activity. We talk about the act of living, implicitly acknowledging that life is an activity. But we have no word for the act of being conscious. So we end up talking about life when we really mean the activity of consciousness. When we talk about human life we usually mean human consciousness. Brain death is the irreversible end of consciousness not the end of life.

This confusion has serious ethical consequences but I don't want to deal with them in this article.

We have only one known case of the formation of life from non-living systems. It probably happened on Earth or Mars over 2 billion years ago but after planetary formation 4.5 billion years ago. Eucaryotic cells first formed from prokayotes over a billion years ago. Animals , plants and fungi separately formed from protists at times from over three hundred million to probably about eight hundred million years ago. It looks like it is easier to form a new level of autopoetic organization from existing life forms than it is to form the base level of life from non-life.

There are several possible origins for viruses. They could be remnants of pre-cellular stages in the formation of life. They could be example of extreme parasitic degeneration. (When a life form becomes parasitic it tends to simplify and loose structures needed by free-living forms but not by parasites.) They could be rogue host genetic material and proteins. I think the pre-biotic remnant speculation is unlikely. I suspect that most of them originated as rogue host material. (Not necessarily material from their current host species. Viruses do jump from one host species to another.)

If you want to read further on the nature of life I recommend What is life? by Magulis and Sagan.

Wednesday, March 16, 2005

Life and life

Life! You know it when you point at it but you find it difficult to say just what it is. I am going to try to pin down the characteristics of an entity that make you say "That's alive.". I want to look at other systems that have similar properties but which we do not normally think of as alive. Then I will look at the differences between these systems and systems which we think of as alive.

In my next post I will look at things which are described as life but are arguably not. These are mostly activities which are dependent on life.

What I am doing in this article is trying to clarify my own thinking on the subject. I hope that readers might find my ideas worthy of contemplation and discussion.

The first question about life is "Is it a process or an entity, an activity or a thing?". Is life a substance or force permeating living beings which is not present in non living entities? Or is life the activities that go on in living beings?

Well, the way you know if something is alive is by what it does. If it is inactive and unchanging one identifies it as being dead. This suggests that one should think of life as what goes on in a living being. One should only propose the existence of a life force if there is no other way to explain what is going on.

In the 1950s and 1960s we uncovered the physical bases of heredity and the energy transport mechanisms. Inheritance turned out to be coded on the nucleic acids, ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). Energy was found to be transported by adenosine triphosphate (ATP). While much of the mechanism of life is not understood, there seems to be no reason to believe that any unknown principles of physics or unknown forces are involved.

(An aside. In the nineteenth century developments in biology and geology did suggest that there were energy sources unknown to contemporary physics. Evolution in biology and uniformitarianism in geology required a vast age for the Earth. Known energy sources could not explain how the internal heat of the Earth or the heat of the Sun was maintained over such a long period. This problem was solved with the discovery of nuclear energy.)

Life is a property of a system not of any individual part of a system. You cannot point to a molecule in a cell and say "That molecule is alive.". A protein or lipid or carbohydrate molecule is the same inside or outside a living cell. One cannot look at any particular chemical reaction and say "This is life.".

OK. So what is it about a system that has us saying "This cell or this organism is alive."?

One answer I have seen is reproduction. However this by itself is not it. A sterile organism can still be alive. A worker bee is not dead. Neither is a pet that you have had sterilized.

The best candidate that I have seen is autopoiesis. This is self maintenance. An autopoietic process brings about its own continuation and the maintenance of the structure in which the process occurs. An autopoietic system replaces its components with new ones that it has created. This description fits cells and it also fits organisms. However it can be argued that it also fits organizations such as corporations, states and ant nests. These are not exactly what one thinks of when one talks about life.

I think we can say that all living systems are autopoietic but not all autopoietic systems are alive. Systems that we describe as alive are self-contained bounded physical systems rather than systems linked by a network of concepts. Thus life is a property of a definite physical body whose individual components were created by that body. I am not sure just what properties as well as autopoiesis are required for a system to be described as alive.

Reproduction of living systems uses the mechanisms of autopoiesis. New organisms are created by the living organism using components that it has created and organized into another autopoietic system. However a self replicating system does not have to be autopoietic. It can simply create copies of itself without maintaining itself or doing anything much except replication. It can also replicate itself by taking over another system and making that other system replicate it. Examples of this behavior are the activities of viruses and prions.

Living organisms do not live forever. To allow a kind of life to persist some members of a kind have to be able to reproduce that kind. Thus self-replication is a property of all entities that we normally think of as life forms. However not all members of a kind have to be able to reproduce. An organism can produce both sterile and fertile offspring. Bees and ants provide good examples of this.

Living cells are the most obvious examples of living systems. They are elaborate structures made up of organic matter, water and inorganic materials (mostly as ions in solution). They are maintained and replicated by physical and chemical interactions among the components.

However the components of an autopoietic system do not have to be organic molecules or organic structures that are not alive by themselves. (A cell membrane is a universal part of all known living cells. Isolated from a cell it cannot be described as alive.)

The components of an autopoietic can themselves be autopoietic systems. This is the case in multi-cellular animals, plants and fungi. These originated as multi-cellular colonies. The cells became differentiated into many types and organized into structures in new autpoetic systems. The cells can be isolated from an organism and grown by themselves in unorganized tissue cultures. The culture is not an autopoietic system though the individual cells that it is made up of are. A mouse is autopoietic system and the cells that it is made up of are also autopoietic systems.

Thus life can be recursive. It can exist on multiple levels. The life of a mouse is not the life of its cells though it depends on the life of the cells. One can make a case for even higher levels of autopoietic organization. For example a bluebottle (Portuguese man o'war) is a colony of multicellular polyps. There are several specialized types of polyp in a colony and an overall structure.

If autopoietic systems organize into a higher level system the individual components can loose the ability to maintain themselves. They can become dependent on their interactions with the other formerly independent systems. That is, living organisms can organize into a higher level living system and the lower level of life can then be subsumed into the higher level of life. This appears to be what happened when eucaryotic cells were formed. (Life can be divided in procaryotic and eucaryotic organisms. Procaryotes have relatively simple cell internal structures. Eucaryotes have elaborate membrane bound cell internal structures. Procaryotes are the bacteria. The eucaryotes are the protists, the animals, the plants and the fungi.) The eucaryotic cell probably formed as a symbiotic association of several different types of bacteria. Examples of cell organelles that were once independent organisms are mitochondria, plastids, flagella and cilia and the nucleus. I would not regard these as being autopoietic systems in their own right any longer.

Another possible example of a higher level autopoietic system composed of autopoietic sub-systems is the biosphere of the Earth as a whole. The Gaia hypothesis regards the entire biosphere as a self regulating system. The hypothesis is that action of living organisms maintains the planet in a condition suitable for life. A system of feedback loops stabilizes the climate and and atmospheric composition etc. The main components of the system are bacteria. Other living organisms, the atmosphere, the hydrosphere and the outer layers of of the lithosphere could also be regarded as components of the system. Under this hypothesis the Earth would be an example of an autopoietic system that does not reproduce. The Gaia hypothesis is sometimes criticized as being a fuzzy mystical approach. I see it as a useful way of looking at a complex of feedback loops. It is a plausible, probably correct but unproven hypothesis.

All the known examples of life ultimately depend on aqueous organic chemistry. In principle this does not have to be the case. One sees many examples in science fiction of other kinds of life. Life with liquid ammonia or other solvents instead of water, life based on silicon rather than carbon compounds, metallic life forms, life based on nuclear reaction and so on. Some of these alternatives could be possible. Some probably aren't. But this is a problem for another generation to solve.

Most of the material in this article is not original. I suspect that many of the original ideas have also occurred to others. The assembly, organization and assessment is mine.

Wednesday, March 09, 2005

Why am I doing this?

A bit of introduction first.

I am a statistician who has worked on a wide variety of projects. The majority have been environmental, agricultural or medical but I have also worked on some social statistics. I also have qualifications in biology.

My interests include such things as science fiction (both written and on the screen), role playing games, war games, art, bush walking, good food and wine, comics and reading about all sorts of things.

My knowledge about some of these things is a bit spotty. Other things I have a good layman's knowledge about. Some of the things above I know a lot about. All in all I have acquired information about an unusual assortment of subjects. This sometimes leads to seeing things a bit differently. Ideas about quite a few subjects have been stewing for a long time and now I intend to serve them up.

To some extent these posts will be thinking out loud about some topics. There is also an element of tossing ideas up in the air for discussion. I hope this whole thing doesn't sound too vain. (Well, blogs are a form of vanity press.)

I will cover whatever takes my interest or whatever I feel strongly about. Science and politics are likely to be the subjects of most of the initial posts. Some of the viewpoints published here will be original, most will not. However much of the unoriginal material will be unfamiliar to many readers.