Abstract. In search for a fundamental mechanism able to create semiosis, we found that the mechanism of differential reproduction inside the two-level self-reproductive system might serve as such. Differential reproduction is also the main mechanism of adaptation. Previous investigators have shown partial isomorphism between the mechanisms of adaptation, recognition, and cognition. From that we can go on to conclude that semiotic processes cover a large part of biology, so we can speak of semiotics as the basis for biology. If so, we should try to formulate the semiotic paradigm in biology. We should also regard the neovitalistic trend in biology as an early development of semiotic paradigm. So we shall dwell on this as well as the problems of the origin of species, the species' co-existence and then differentiation, and shall try to obtain new solutions from the standpoint of the semiotic paradigm.
"Towards a Theoretical Biology" - the four symposia and four volumes [36; 37; 38; 39] of original papers under the leadership of Conrad Hal Waddington - made a history in biological thinking. They did not propose many ideas for biological textbooks, they presumably did not discover any new biological mechanism or even law, but they showed a new type of enthusiasm in dealing with biological knowledge, giving a new meaning to theoretical biology. That is why I would like to repeat again the conclusion made in the epilogue to the final volume of "Towards a Theoretical Biology": "It has always been clear that we were not so deeply interested in the theory of any particular biological phenomenon for its own sake, but mainly in so far as it helps to a greater comprehension of the general character of the processes that go on in living as contrasted with non-living systems ... The situations which arise when there is mutual interaction between the complexity-out-of-simplicity (self-assembly), and simplicity-out-of-complexity (self-organization) processes, are, I think, to be discussed most profoundly at the present time with the help of the analogy of language ... Most of the biological problems we have discussed can be seen in terms of the language-metalanguage analogy ... At any rate biologists who pursue this line of thought will be assured that they will find themselves in stimulating company ... But what is a language essentially? In my opinion, biology can make some real contribution towards answering this question ... And it is language in this sense - not as a mere vehicle of vacuous information - that I suggest may become a paradigm for the theory of General Biology" [47, pp. 283, 285, 286, 287, 289]. The other reason is that
it is probably the first time when it was declared that semiotics could be the basis for biology.
During the twenty years since the Waddington's conclusion, there was not very much done in biosemiotics from the standpoint of the theory of general biology. Presumably several important investigations were provided in general linguistics, assuming their possible application in biology . Nevertheless, we can notice certain rise of interest in biosemiotical problems in last decade [1; 3; 9; 16; 23; 33; 45]. Particularly, the old problem of biological basis of cognition [17; 13; 26] was developed by several scientists and philosophers [2; 7; 8; 14; 25; 30; 31]. M. Anderson et al.  have listed different areas of biological research where semiotic challenge could contibute the solution of problems - biogenesis, coevolution, endosymbiosis, synthesis between macroevolutionary and microevolutionary theory. There has been also a remarkable rise of interest in Jakob von Uexküll's works in recent years [3; 43; 44].
In October, 1988, a workshop "Semiotic approach in theoretical biology" was held at Laelatu Biological Station (Estonia). The people who had organized the conference "Biology and linguistics" (as a part of the Winter School in Theoretical Biology) in Tartu in February, 1978, met again. Since 1988, one of the participants, Alexei Sharov, started a series of seminars and Winter Schools on Biosemiotics in Moscow University. Another participant, Sergei Chebanov, established a similar activity at the University of St.-Petersburg. Students of the Theoretical Biology Group of Tartu University devoted to biosemiotics an issue of their periodical "Vita aeterna" (no. 5, 1990). So, we can say that the Waddingtons's conclusion has not been entirely forgotten.
In our recent work  we tried to formulate the main mechanisms which transform the biological systems into semiotic ones. In compiling a sketch of semiotic paradigm in biology, we shall give here several interpretations of biological concepts from the semiotic point of view.
The sketch below is a very provisional and superficial list of several basic notions. There is still a lot of work to be done in developing it into an exact system of assumptions and consequences. Here we present some ideas as to the construction of the theoretical system for theoretical biology. For theoretical biology could do with a comprehensive theoretical system.
The biosemiotic approach makes it possible to include into the apparatus of the theory of general biology such notions as meaning, sign, purpose, value; it should give new interpretation to the teleological and quasi-teleological notions in biology, such as adaptation, evolutionary progress, selfishness; it could evaluate the terms applied in neovitalism and integrate them into the system of mechanistic biology (or vice versa) [cf. 46].
The self-reproductive system with an ability to mutate represents the most fundamental counterpart of all living systems. Many attributes of life are direct logical consequences of the definition of a self-reproducing system.
The existing definitions of a self-reproducing system (SRS) on the basis of the Petri nets or differential equations formalism [22; 32; 34] do not include directly the assumption of variability into the definition. It is understandable, because there could exist self-reproducing systems without the ability to make changes, even small ones. The formalism used is also not good enough for the description of hierarchical systems.
According to our understanding of the theoretical system of biology, the various features of biosystems which are not direct consequences of self-reproduction, should be combined into a model of self-reproduction that would enable us to derive more concrete models of living systems.
Darwin used the assumption of small variations. It gives very important additional features to the SRS - the variation curve and its changeability. It provides for the ability to move, or to change adequately. The adequate change should be understood not as a feature of a single SRS, but a feature of the whole population of SRSs. In a general case, still, a population as a set of elementary SRS is not an integrated entity which has epiphenomena belonging to it as a system. But population can be an independent system if it has some additional features (mechanisms) integrating it into one whole. E.g., this may be cross-fertilization, making from a population a SRS of a higher level. There might be various mechanisms of aggregation which can convert a population of single independent individuals into an integral whole . A population as an integral whole is a SRS, whereas a population of non-interacting individuals is not. The integrity might be given to the population also through the interaction with some other system which interprets (recognizes) the population as a whole (e.g. confusing the specimens of the population but distinguishing them from the specimens of other populations) if the interaction is important for the reproduction of the population. This type of integrity is characteristic of eco-species (see below). Thus, the two-level SRS means that the population of SRSs is also a SRS.
The two-level SRS with an ability to carry small variations in the lower level is a system capable of purposeful changes. If, in the case of a one-level SRS, any change of its hereditary structure turns it into another SRS, then in the case of a two-level SRS the analogous change in the lower-level SRS means certain variation in the inner structure of that same two-level SRS.
The mechanism of semiosis should contain, according to its definition, three counterparts - the signifier, the signified and the interpreter. Let us assume that a two-level SRS contains SRSs of two or more slightly different types. In the case of interaction with an environmental agent, the speed of reproduction of these SRSs of different types might be also different, and the relative number of them will undergo a change, so that the SRSs of a higher speed of reproduction will be more numerous. Then, the interaction will change the population of SRSs, so that it will have a higher efficiency of reproduction during the next interaction with the
same agent. We propose to interpret it as the simplest case of triadic interaction, or semiosis.
The environmental agent will turn into signifier after it has interacted with the system (two-level SRS) and the latter has changed toward becoming a more effective multiplier in the conditions of having this agent in its environment. Hence, the agent has become a signifier, which has certain meaning for the interpreter (= for the two-level SRS). And this meaning is - being favourable to its reproduction. Thus, a part of the environment has obtained a value for the system. The signified or meaning could also be interpreted using other, more biological terms: the signified is recognition, or adaptation. Biological recognition and biological adaptation represent the simpliest forms of semiosis.
The meaningful part of the environment is 'Umwelt' in J.v. Uexküll's sense .
An important early contribution to biosemiotics has been made by J. von Uexküll. In his "Bedeutungslehre" , which is one of the first books on biosemiotics, he stated that 'meaning' has a universal status in living systems.
This interpretation of the concept of 'meaning' has been usually taken as standing apart from traditionally semiotic interpretations, because it seems to give too broad a content to this term without a clearly visible interpretation in the context of the triadic structure of semiosis. But, applying the interpretation of semiosis proposed above, we get the analogous understanding of 'meaning' to the one proposed by Uexküll [43; 44].
"Der elementarste Zeichenprozeß, gewissermaßen das 'semiotische Atom', läuft daher in der lebenden Zelle ab, die jeder Einwirkung, die sie überhaupt beantwortet, ihre spezifische Bedeutung erteilt, d.h. sie nach ihrem spezifischen Kode verschlüsselt und dann mit ihrer spezifischen Antwort reagiert. Damit tritt hier zum erstenmal in der Natur eine Qualität auf, die wir als 'Selbst' oder 'Eigen' bezeichnen, d.h. die Fähigkeit eines Gebildes zwischen Selbst und Nicht-Selbst zu unterscheiden. Die 'spezifische Lebensenergie' Johannes Müllers definiert in semiotischer Terminologie das 'elementare Selbst'" [43, p.41].
From the latter we can get an idea how the notions used by the biologists of vitalistic paradigm might be applied in the contemporary biology by means of semiotic terminology.
It is also important to emphasize that semiotic relations have been characteristic of living beings since the very early stages of their evolution, as the simplest population of cells already may represent the two-level SRS.
"Suppose we regard living organisms as systems which generate and test hypotheses about their environment. At the psychological level this has fairly direct intuitive meaning. But what would it mean about a bacterium? It would mean that such a system has a set of hypotheses which are present in coded, symbolic form in order to satisfy our intuition about the nature of hypotheses; that these must be subject to variation and test in relation to an external world; and that there must
be some principle of correspondence whereby 'good' hypotheses about this world can be retained and stored while 'bad' ones are discarded." [10, p.268-269].
"It is my central idea or strategy that the essence of the matter-symbol problem and hence the measurement or recording problem must appear at the origin of life where the separation of genotype and phenotype through language structures took place in the most elementary form." [28, p. 253].
The meaning can arise only if the system has any needs for something (e.g., for food, for warmth). But the existence of needs presumes self-reproduction. Because - applying Dawkins'  metaphor - only self-reproducing systems might be egoistic.
Biosystems are hierarchic systems in the sense that they consist of several SRSs of different levels. Consequently, there is a hierarchy of Umwelts, hierarchy of adaptations, and hierarchy of meanings.
J. Piaget has noticed a partial isomorphism between the organism and the epistemological subject . K. Lorenz has written about life as a cognitive process . And A. Heschl has further developed this idea up to its logical end. "It is just the concept of cognition that will turn out to be the decisive criterion for the "mystery" of life" [14, p. 18]. "Life and cognition are revealed as truly synonymous notions" [14, p.20].
The same thought has been independently entertained by several other authors as well. "Lebende Systeme sind kognitive Systeme, und Leben als Prozess ist ein Prozess der Kognition. Diese Aussage gilt für alle Organismen, ob diese ein Nervensystem besitzen oder nicht. " [25, p.39]
"Behaviour involving the cognitive processes can in fact be viewed as the continuous formulation, testing, and improvement of hypotheses according to criteria of behavioural success, whatever this may be. This context thus provides a natural framework within which to compare and contrast different levels of biological organization." [10, p.271].
Almost the same has been written by several biologists of neovitalistic trend. "Die lebende Zelle verhält sich äusseren Objekten gegenüber nicht als Objekt, sondern als Subjekt" [40, p.386]. "Das Subjekt ist der neue Naturfaktor, den die Biologie in die Naturwissenschaft einführt." [40, p. 389]. The 'Umwelt' is the subjective environment.
A set of different particular semiosis (recognitions, adaptations) forms a language, if the same type of interaction could result distinctively different behaviour, i.e. if meanings are separated by hiatuses. In the case of minimum text it means, that at least two things are recognized by a biosystem as different things, and between the meaningful areas there is an unrecogizable area or hiatus. The mechanism
creating language needs interaction between at least two two-level SRS, i.e. it needs dialogue (which is analogous to biparental reproduction).
DNA-RNA-protein interactions are often considered as representing a good example of biological text or language. But interpreting it in truly semiotic terms and mechanisms, one should consider, that it is a result of dialogue between SRS.
According to Darwinism, natural selection as differential reproduction in genetically diverse populations is a mechanism creating adaptations. "Many of the hereditary characters of organisms conform to some feature of their normal environment in such a way as to benefit the organism. Such characters are adaptive" [12, p.6].
The process of adaptation is always taking place whenever there is differential reproduction in genetically diverse population. Therefore all living beings are (in some extent) adapted, because they have undergone differential reproduction during their previous evolution. Biologists often use such expressions as 'one organism is better adapted than the other'. It means that they presume the existence of some measure of adaptation. Usually it is assumed that the measure of adaptation is fitness, but the problem needs thorough analysis .
The obvious automatic result of interaction between the environment and the two-level SRS is always adaptation (if it is not death or mutation). Using the semiotic interpretation of this interaction we get a semiotic interpretation of adaptation. The similar idea was expressed by A. Heschl, who showed the equality of cognitive and adaptive processes [14, pp. 24, 34]. So the process of adaptive evolution appears thus to be also the process of evaluation. Adaptation is a semiotic phenomenon.
Darwin has made an important distinction between natural selection and sexual selection. The importance of this distinction has not been always understood by the followers of Darwin. But it has become much clearer after the development of the 'recognition concept of species' by H. Paterson [27; 19; 20]. Sexual selection is actually a reciprocal natural selection, when the interacting systems are both SRS. Unlike natural selection where the SRS interacts with the environment, the interaction between two SRS leads to the creation of regular discreteness in the (morphological, temporal and spatial) distribution of SRSs . It is the actual reason for the origin of regular species [20; 21].
Pairs of co-evolutionary species (lichens; vascular plant+mycorrhiza; vascular plant and herbivory monophagous insect; eukaryotic cell and its endosymbionts; bacterium+virus) often represent the existence of regular hiatuses between the species-like populations only consisting of organisms of quite different genotypes. A good example here is represented by lichens. The interpretation we can apply here is that in the situations listed above the interaction is taking place between many-level SRSs, yet despite the higher number of levels in a SRS, the
general mechanism of biparental reproduction and the resulting speciation-like process is similar to those in usual speciation.
Thus, the species-like groups of SRS are of three principal types:
a) co-species - an eco-species which is preserved by recognition between specimens of the eco-species and a species, whereas the recognition is needed for the reproduction of the specimens of the eco-species; several uniparental organisms which form morphologically clearly distinguished groups might represent examples of co-species if their range of variability is delimited by the recognition of certain species (e.g. in their trophic interaction); possible regularity of co-species is determined by the regularity of species;
b) geo-species - the ecospecies whose range of variability is delimited by the width of closed 'valley' in the 'adaptive landscape' of abiotic conditions; abiotic conditions do not usually form regular rows of valleys, and consequently, geo-species cannot represent regular sets; certain uniparental organisms may form geo-species;
The mechanism responsible for differentiation in multicellular organisms, as a rule, contains recognition. Recognition between extracellular agents and cells, through specialized structures on the cell surface, is an important mechanism of cell regulation. Cell cohesion and cell-cell recognition mechanisms play obligate role in morphogenesis. As far as in many cases certain morphogenetic event presupposes specific interaction between two cells, we can say that it presupposes biparentality, with all its consequences.
The efficient recognition presupposes coincidence of periods of competence. In the case of temporal shift, the effects of heterochrony appear [11; 15].
SRS represents a destabilizing force in a system where it exists. If there is more than one type of SRS in a system, the problem of their coexistence arises. There have been some attempts to use semiotic approach to solve it .
The explanation of coexistence of species inhabiting similar niche has been a permanent problem for ecologists. This problem called 'paradox of plankton' by E. Hutchinson will get further explanation if the semiotic approach is applied here based upon general features of biological recognition.
It has been proved that the stable coexistence of SRSs could be possible if the density of every separate type of SRS (species) of the community is limited intrinsically, by the intra-specific competition. The problem is, how general this assumption is. If the assumption holds true, then the productivity of community of more than one species should be always higher than the productivity of any counterpart species in monoculture in the same conditions.
The experimental measurement of competition in field conditions meets with serious difficulties. There is also a theoretical difficulty in finding a general unit for the measurement of competition which could be applicable both for the interspecific and for the intraspecific competition.
Considering the large number of different ways through which the competition interaction may occur, we probably cannot reach a simultaneous measurement of all of them. Each difference in behaviour or structure between the species may play an important role in changing the intensity of competition.
Any difference between organisms may potentially reduce the competition between them. The specimens of the same species are more similar than the specimens of different species. From this we can conclude - the reciprocal intraspecific competition is stronger than reciprocal interspecific competition, and therefore, the assumption made above is of quite a general value.
Despite of using the term 'recognition' here, it does not mean that the mechanism itself is a semiotic one. There could exist both semiotic and non-semiotic mechanisms of coexistence of SRS. It also means, that not all the phenomena we can see in living world are semiotic ones. But the essence of life is semiotic.