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What is Biosemiotics?

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Summary

Biosemiotics (bios=life & semion=sign) is an interdisciplinary science that studies communication and signification in living systems. Communication is the essential characteristic of life. An organism is a message to future generations that specifies how to survive and reproduce. Any autocatalytic system transfers information (i.e. initial conditions) to its progeny so that daughter systems will eventually reach the same state as their parent. Self-reproducing systems have a semantic closure (Pattee 1995) because they define themselves in their progeny. A sign (defined in a broadest sense) is an object that is a part of some self-reproducing system. A sign is always useful for the system and its value can be determined by its contribution to the reproductive value of the entire system. The major trend in the evolution of signs is the increase of their complexity via development of new hierarchical levels, i.e., metasystem transitions (Turchin 1977).

Ouroboros

The Ouroboros is a mythological serpent that chews its own tail. According to another interpretation, the Ouroboros is building itself from its mouth. I selected the Ouroboros as a symbol for biosemiotics because it represents self-reference or, using the term of Pattee (1995), semantic closure which I believe is the essential feature of any organism and any sign. Biosemiotics (bios = life and semion = sign) is an interdisciplinary science that studies communication and signification in living systems (see introductory texts on semiotics: 'Communication' and 'Semiotics for Beginners'). Moreover, it considers communication as the essence of life. But what is communication and what are signs? We are used to these terms because we use signs in our everyday life. But is it possible to define a sign without referencing to humans? I am going to show that this is possible using the conception of semantic closure (Pattee 1995).

Short history of biosemiotics

Uexküll (1940) developed a theory of meaning which considered animals as interpreters of their environment. He called this subjectively interpreted environment Umwelt ('Umwelt' means 'environment' in German). Uexküll (1940) considered only living organisms as interpreters. He pointed that the ability of animals to interpret the world helps them to perform their functions. However, his conception of usefulness (adaptation) was not based on the theory of natural selection which he denied.

The theory of zoosemiotics (Sebeok 1972) contributed to a further integration of biology and semiotics. Signs used by animals (visual, acoustic, and chemical) are processed by their nervous system in the same way as in humans. Thus, it was natural to expand semiotic notions from human semiotics to zoosemiotics (Sebeok 1972). Further studies indicated that interpretation of signs does not necessary require a nervous system. Krampen (1981) suggested that even plants are capable of interpreting signs although they have no nervous system. According to these studies, biosemiotics is a specialized branch of semiotics that focuses on communication in living systems. Pattee (1982) suggested that communication is the essential characteristic of life. Thus, biosemiotics should be viewed as a root of both biology and semiotics (Sharov 1992). Hoffmeyer (1997) developed this view showing that any organism is a message to future generations that describes the art of survival and reproduction.

The term "biosemiotic" was first used by F.S.Rothschild in 1962. For a detailed history of biosemiotics, see the paper of K. Kull. Kalevi Kull comipled a useful list of definitions of biosemiotics and references.

Values and semantic closure

Traditional physics never studied values (i.e., usefulness) of objects. But the notion of value is very important for understanding the phenomenon of life. Values can be applied also to various kinds of activity: eating, sleeping, moving, growing, reproducing, etc. By evaluating objects and processes, an organism subjectively interprets the world and itself, i.e. it builds its Umwelt (Uexküll 1940).

Usefulness is not a quality but a relation between an object and user. But at a closer look, a user is nothing but a collection of useful objects. Organs are tools that are used by an organism for performing specific functions, but there is nothing in the organism besides organs. Thus, the user is just a set of relations between useful parts. Obviously, not all kinds of relations can be considered useful. Some relations may destroy the system. Relations are useful only if they preserve and augment the same relations in the future, i.e., if these relations are self-reproducing. This idea was first formulated by Pattee (1982, 1995) and was called "semantic closure". Semantic closure is a new criterion for autonomy (or wholeness) of systems. A set of elements connected by relations is autonomous only if it is semantically closed, i.e., it reproduces itself in the future and defines its identity in the process of self-production. The value of each component or relation in an autonomous system corresponds to its contribution to the ability (or probability) of the system to reproduce itself.

The notion of value was introduced to biology by Fisher (1930). He defined reproductive value of an organism as its contribution to the growth of the entire population. For example, eggs have a smaller reproductive value than adults because adults can easily produce multiple eggs, but it takes a long time for an egg to develop into adult. In simple organisms that are not able to learn from their individual experience, natural selection is the mechanism that maximizes the value of organisms at each step in the life cycle. Higher animals can estimate the values before natural selection will take place. Thus, they are able to optimize their behavior without mortality. Fisher (1930) defined values only for entire organisms, but this definition can be extended to the parts of an organism and to relations between parts. The value of a part (or relation) is equal to its contribution to the process of self-reproduction. For example, the value of the resource is equal to the gain in reproductive value of an organism that captured this resource unit.

Biologists may ask why to use semiotic terminology in simple population models? In particular, why to talk about semantic closure instead of self-reproduction? "Self-reproduction" seems to be a convenient term that does not have uncertainties associated with signs or semantics. But this simplicity is illusive; self-reproduction includes the word "self" which comes from the field of semiotics rather than physics or biology. In the process of self-reproduction, an organism defines itself; in other words, self is what is preserved in the process of self-reproduction. Self-reproduction is simultaneously a process of self-measurement, self-interpretation, and communication from parents to offsprings.

Peirce (1955) defined a sign as a triadic relationship between a sign vehicle (representamen), an object, and interpretant which is a representation of the object in human mind invoked by the sign vehicle. The interpretant is a mental model of an object. Bacteria are not able to build mental models of objects but they can build material models of themselves, i.e. their offspring. Genome can be viewed as a sign vehicle that is interpreted in offsprings. It tells offspring organisms how to develop, survive, and reproduce. The message is true because it was verified by natural selection in numerous generations. In simple autocatalytic systems, genome is not represented by a specialized structure (e.g., DNA), and the entire system can be viewed as a message (i.e., sign).

Normal communication requires that signs have positive values both for a producer and receiver (Sharov 1992). An organism spends its resources to produce a sign only if the sign has value, i.e., it increases the rate of self-reproduction either directly or indirectly. In the same way, the receiver never interprets a message unless it expects to increase its fitness after interpretation. Here I mean expectation in a broad sense including evolutionary (unconscious) expectation. Only in higher animals and humans expectation becomes conscious. But in some cases, the value of signs may be negative. For example, some predators may intercept signals produced by their prey. In this case, the value of a sign is negative for the producer. Other predators may emulate signs that attract their prey. In this case, the value of a sign is negative for the receiver. But negative values are not normal. If a sign has negative value too often, then organisms will simply avoid using it.

Human signs also have values, but this value is no longer connected with biological reproduction. Human evolution is driven more by the propagation of life styles (memes) rather than by propagation of genes. Memes are associated with specific human relations (e.g., ethical, religious, educational, etc.). The value of texts is associated with propagation of these relations. Peirce (1955) described only a half of the life cycle of a sign, i.e., the process of perception and recognition. He did not analyze the process of sign production which closes the cycle (semantic closure). According to Pattee (1995) each sign participates in a larger system with semantic closure.

Metasystem Transition

The major trend in the evolution of signs is the growth of their hierarchical structure. Simple autocatalytic systems represent a single hieroglyphic without internal structure. More advanced systems develop hierarchical signs. Development of new hierarchical levels in autonomous systems was called metasystem transition (Turchin 1977). Metasystem transition starts with duplicating of original systems and ends with establishment of a new semantic closure (Turchin used the term "control"). For example, multicellular organisms originated via duplication of cells that stayed together and cooperated.

Symbiosis is another mechanism of metasystem transitions which was not mentioned by Turchin (1977). Several non-similar systems may start cooperating, and this cooperation represents semantic closure at a higher level. For example, lichens are symbiotic organisms that originated from fungi and algae; eucaryotic cells originated from a symbiosis of several types of procaryotic cells.

When two autocatalytic systems cooperate, they produce resources for each other. Resources, as we have seen in the previous section, are primitive signs. Thus, cooperation is a semiotic relationship. Each component has a double interpretation in such a system. First, it is self-reproducing on its own (self-interpretation), and second, it produces signs that are interpreted by another component.

The major obstacle on the way of cooperation is possible evolutionary instability. Let us consider cooperating chemical species A and B that produce resources for each other. Species A may "mutate" into a selfish species A1 which will use resources produced by species B without providing help to the species B. As a result, the cooperation between species becomes broken. Cooperation is evolutionary stable only if specific restrictions are applied on communication (resource exchange). I call these restrictions "encapsulation". For example, several representatives of species A and B may form small groups, so that communication occurs only among members of a group. If a selfish mutation destroys communication within a group, then this group will become less competitive and eventually will be eliminated in the process of group selection. Thus, encapsulation makes a metasystem transition possible. Hierarchical systems have several levels of encapsulation and this makes them more stable than systems that have no communication restrictions.

Each self-reproducing component in a hierarchical system defines its own values. Thus, there is a hierarchy of values. A message may have value for several components. For example, growth hormones stimulate proliferation of individual cells and thus, they have a positive value for a cell. But the same hormones may change the morphology and function of a multicellular organism. These changes may be beneficial or harmful. Also, growth hormones may cause cancer which is fatal for an organism.

The value of an element at a higher level may be reduced if there is a conflict of values among its components. Thus, natural selection favors those hierarchies in which conflicts are minimized. The fitness landscape of components usually does not have a single sharp peak. Instead, there is a region of neutrality where fitness is almost the same. Thus, the super-system may examine neutrality regions of its sub-systems and find points where conflicts between sub-systems are minimized. The system creates a higher-level value without damaging lower-level values.

Biosemiotics and philosophy

Philosophical views of people working in the area of biosemiotics are different and can not be described here exhaustively. But I would like to outline briefly my own philosophical position just to make it explicit. The reason to do this is because I think that my philosophical views are not just applied to the area of biosemiotics but rather originate from biosemiotics.

My views are most closely related to pragmatism of Peirce and James. According to pragmatism, the ultimate measure of truth is usefulness (=value). Among other related theories I can point to creative evolution of Bergson and paradigms of Khun

Pragmatism is opposed to realism which assumes that properties of the real world are observer-independent. Realism attempts to remove the observer from knowledge in order to consider this knowledge objective and absolute. Realism includes materialism and objective idealism. Because knowledge is expressed in language, realists assume that words have observer-independent meanings. Their favorite model of language is formal logic in which truth-values are specified in a meta-language (Tarski). Truth is determined syntactically in the same way as we prove theorems. The correspondence between facts and theories is syntactic too because both are expressed in the same formal language. See 'objective epistemology'. Tarski considered the sentence "It is raining" true if it is really raining. But there is no exhaustive definition of "raining"; any existing definition can be further clarified and specified. Even the word "water" can not be defined (see the discussion on twin Earth).

Biosemiotics, on the contrary, emphasizes the role of observer. Each living organism builds its own world, its own reality (Umwelt). This world includes the body and surrounding objects which an organism uses in its activities. Advanced organisms can produce signs that correspond to elements of their Umwelt. Each human being has its thesaurus by which he can describe his Umwelt. A language is a result of agreement among communicating individuals on how to use specific signs. Thus, sentences in human language have no absolute and fixed meaning; meaning is conventional. Testing hypotheses is a semiotic process: we apply old words to new objects (widening or narrowing the meaning of words). Instead of a uniform objective knowledge for everybody I prefer to consider different kinds (i.e., levels) of knowledge. Each person gets the knowledge he is capable to grasp. The whole process of evolution is the movement from primitive knowledge to more and more advanced knowledge

Biosemiotics is rather close to evolutionary epistemology in the following aspects. It considers knowledge as a natural phenomenon which can be studied using the evolutionary theory. Biosemiotics is a descriptive science and rejects normative epistemology and normative ethics. In other words, it does not tell you how to learn and how to live. Instead, it describes how learning usually occurs and what strategies of life are usually successful. This does not mean that normative epistemology and ethics should be dismissed. It is known that some people want to know explanations whereas other people are satisfied with instructions and directions. Normative epistemology and ethics are definitely needed for people in the second category.

However, most people who develop evolutionary epistemology are realists, including the founders (Campbell, Lorenz, and Popper). Popper thought that scientific language has fixed meaning, and therefore scientific knowledge is objective and absolute. I think that there is no absolute (observer-independent) knowledge. However, there may be levels of "objectivity" depending on the scope of usefulness of knowledge (how large is the group of people who apply this knowledge and how successful this application was in the past). In this sense, scientific knowledge is more "objective" than superstitions.

Realists argue a lot about religion. If a realist is an atheist he thinks that the absence of God is an objective knowledge. Thus, he tries to prove to other people that God does not exist (e.g., Dawkins). If a realist is a believer, he will fight for his specific confession considering it as ultimate truth. In contrast, pragmatism is tolerant to religion. God is a very important part of the Umwelt of a religious person. Religious experience has proven to be useful for billions of people. But other people may not need it. Because people have different Umwelts they cannot come to agreement on whether the God exists or not. But this disagreement does not prevent them to communicate using overlapping portions of their Umwelts. It is not the goal of science to prove that Got does not exist; science has other more important goals.

References

Fisher, R. A. 1930. The genetical theory of natural selection. Clarendon Press, Oxford.
Hoffmeyer, J. 1997. Signs of meaning in the Universe. Indiana University Press, Bloomington.
Pattee, H. H. 1982. Cell psychology: An evolutionary approach to the symbol-matter problem. Cognition and Brain Theory 5: 325-341.
Pattee, H. H. 1995. Evolving self-reference: matter, symbols, and semantic closure. Communication and Cognition - Artificial Intelligence, 12, 9-28.
Peirce, C. S. 1955. Philosophical writings of Peirce. Edited by J. Buchler. Dover Publications, New York.
Sebeok, T. A. (1972). Perspectives in zoosemiotics. Mouton, The Hague.
Sharov, A. A. 1992. Biosemiotics: a functional-evolutionary approach to the analysis of the sense of information. Pp. 345-373. In: Sebeok, T. A. and J. Umiker-Sebeok (eds.), Biosemiotics: The Semiotic Web 1991. Mouton de Gruyter, Berlin.
Turchin, V. F. 1977. The phenomenon of science. Columbia University Press, New York.
Uexküll, J. von 1940 (1982). The Theory of Meaning. Semiotica 42, 25-82.

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Alexei Sharov 04/14/98