University of Copenhagen, Institute of Molecular Biology, The Biosemiotics Group, Sølvgade 83, DK-1307 Copenhagen K, Tel.: (45) 3532 2032, Fax: (45) 3532 2040, E-mail: firstname.lastname@example.org.
The earliest manifestation of this trend is probably in the work of the German biologist Jakob von Uexküll, who in the first part of this century developed his umweltsforschung. The term umwelt refers to the phenomenal worlds of organisms, the worlds around animals as they themselves perceive them. "Every action" wrote Uexküll "that consists of perception and operation imprints its meaning on the meaningless object and thereby makes it into a subject-related meaning-carrier in the respective umwelt" (Uexküll, 1982 ) ; Uexküll's work has been reviewed in (Sebeok, 1979, Ch. 10, and Uexküll, 1982).
Konrad Lorenz was inspired by the work of Uexküll and the growth of the new discipline of ethology, can be seen as the next important step in the semiotisation of nature. It was Thomas A. Sebeok who first explicitly observed that ethology is 'hardly more than a special case of diachronic semiotics' (Sebeok, 1976, 156) and who as early as in 1963 coined the term 'zoosemiotics’ (Sebeok, 1963). Ethology itself has branched into several new disciplines such as 'animal communication' and 'sociobiology'.
A major breakthrough in our understanding of the semiotic character of life was the establishment in 1953 of the Watson-Crick double-helix model of DNA and the subsequent deciphering of the genetic code. While up to this point the semiotic understanding of nature had been concerned mainly with communicative processes between organisms, termed exosemiotics by Sebeok (1976), it now became clear that semiotic processes were also prevalent at the biochemical level (endosemiotics). In 1973 Roman Jakobsen pointed out that the genetic code shared several properties with human language and that both were based on a double-articulation principle (Jakobsen, 1973; Emmeche and Hoffmeyer, 1991). Due to its reductionist inclination, however, mainstream biology did not at the time - and still does not - apply a semiotic terminology (an exception to this is (Florkin, 1974)).
Eugene F. Yates has pointed out the strange shift in vocabulary which has taken place in biochemistry (Yates, 1985). It seems as if modern biochemistry cannot be taught - or even thought - without using communicational terms such as 'recognition', 'high-fidelity', 'messenger-RNA', 'signalling', 'presenting' or even 'chaperones'. Such terms pop up from every page of modern textbooks in biochemistry in spite of the fact, that they clearly have nothing to do with the physicalist universe to which such books are dedicated. As Yates rightly remarks: "There is no more substance in the modern biological statement that ‘genes direct development’ than there is in the statement ‘balloons rise by levity’". Expressions like these even appear in scientific papers. Thus, out of a total of 60 review articles appearing in the 1994 volume of TIBS (Trends in Biochemical Sciences) I counted 27 articles with titles containing terms presupposing a semiotic context.
Rather than talking about sign-processes biochemists prefer to talk about information exchange. According to the mathematical theory of information, information is an objectively existing measurable entity, a property so to say of a given object. The tacit assumption behind the idea of biological information seems to be that such information is the same sort of thing as 'mathematical' information, i. e. an objectively existing property of so-called informational molecules such as DNA, RNA or protein. Thus for instance the famous 'central dogma' formulated by Francis Crick holds that information is always passed from DNA to RNA and from RNA to protein, never the other way around. Information, then, is something which can be moved or transported.
This conception of biological information has been criticised often enough (Rosen, 1985; Yates and Kugler, 1984; Kampis, 1991; Hoffmeyer and Emmeche, 1991; Sharov 1992; Hoffmeyer, 1996). Here I shall content myself to point out that basically when biologists and physicists talk about information, they talk about different kinds of things. While information as understood by physicists has no connection to values, relevance or purpose, biologist think about information in a much more everyday language sense, and in fact biological information always serves a purpose in the system, if nothing else it at least serves to promote survival. The point is that biological information is inseparable from its context, it has to be interpreted in order to work. For example, if we discuss genetic information it should be noted, that contrary to the general image raised in textbooks there is no simple relation between the DNA coded messages and the construction of the organism, whether single celled or multi-cellular (Hoffmeyer 1995c). What is described in the DNA-text mostly concerns the amino acid sequence of the backbones of proteins and even before these backbones are actually assembled, so-called RNA-editing processes may well have introduced a context dependent element in the process (Rocha, 1995). Furthermore, how the amino acid backbones are actually folded into three-dimensional protein molecules is not itself directly specified. Neither is it fully specified how the virgin proteins should be put into the right place in the nearly unbelievably complex architecture of the cell, or how and when, in multi-cellular organisms, cells divide, differentiate or migrate in the embryonic tissue. As Harvard geneticist Richard Lewontin once said: “First, DNA is not self-reproducing, second, it makes nothing and third, organisms are not determined by it” (Lewontin, 1992). A more extended criticism of the DNA-centred view of biological information has been advanced by the adherents of 'developmental systems theory' (Oyama 1985, 1995; Johnston and Gottlieb 1990; Griffiths and Gray 1994).
What all this amounts to is a simple but crucial fact: DNA does not contain the key to its own interpretation. In a way the molecule is hermetic. In the prototype case of sexually reproducing organisms only the fertilised egg ‘knows’ how to interpret it, i.e., to use its text as a manual containing the necessary instructions for producing the organism (Hoffmeyer, 1987; Hoffmeyer, 1991; Hoffmeyer, 1992). The interpretant of the DNA message is buried in the cytoskeleton of the fertilised egg (and the growing embryo), which again is the product of history, i.e., of the billions of molecular habits having been acquired through the evolution of the eukaryotic cell (Margulis, 1981) in general and the successive phylogenetic history of the species in particular. (It took evolution two billion years to produce this marvellous entity, the eukaryotic cell. Having accomplished this deed evolution spent only one and a half billion years on producing all the rest).
While it is understandable that biology as a profession prefers to base its understanding of basic life processes on a concept of information having been developed in the safe world of physics, this way of saving the life sciences from the muddy waters of interpretative processes nevertheless seems increasingly illusory the more we learn about the true subtleties of those processes. Cellular processes are of course chemical processes, but what sets them apart form other chemical processes is the way they are organised around a multitude of cytoskeletal membranes and in response to the dynamic needs of semiosis. Cells like organisms are historical entities carrying in their cytoskeleton and in their DNA traces of their pasts going back more than three billion years. They perpetually measure present situations against this background, and make choices based on such interpretations. Thus, one might well claim that the sign rather than the molecule is the basic unit for studying life (Hoffmeyer, 1996).
In the last decade the trend towards semiotisation of nature discussed here has manifested itself at still new levels. Thus, in evolutionary biology, neo-Darwinism has been seriously challenged by a set of ideas referred to as infodynamics (Brooks and Wiley, 1986; Weber, et al., 1989; Weber and Depew, 1995; Goodwin, 1989; Salthe, 1993). Infodynamics in the words of Stanley Salthe 'subsumes thermodynamics and information theory, essentially animating the latter by means of the former' (Salthe, 1993, 6). The general idea as originally suggested by Dan Brooks and Ed Wiley is that information capacity (disorder) increases spontaneously in developing systems, being produced along with physical entropy as the system grows and differentiates. Since such self-organisation is a prevalent property of our universe, natural selection should not be seen as the dominating force of evolution, but rather as playing the more modest role of pruning down the novelty that is constantly and autonomously being generated by the requirements of the second law of thermodynamics. Elsewhere I have discussed the surprising correspondence between these ideas and the 'cosmogonic philosophy' of Charles Sanders Peirce (Hoffmeyer 1996, see also Salthe, 1993).
Another interesting development from this point of view takes place in the area of 'artificial life'. Here the strong thesis, as presented by Chris Langton, is that life is not a property exclusively of 'flesh and blood', rather life is a formal phenomenon which may be exhibited by a whole range of material substrates, for instance silicon (Langton, 1989). Based on this assumption researchers in artificial life (a-lifers as they call themselves in distinction to b-lifers, the biologists!) have developed a multitude of computer simulations exhibiting this or that property deemed essential for living systems. For a critical review of this area of research see Claus Emmeche (1994) who emphasises the fruitfulness for biology of a dialogue with these competing ideas of life but also expresses his reservations to the strong version of the programme. From a semiotic point of view artificial life research is interesting because it so radically identifies life with its digital informational aspect. Nevertheless, by abstracting life away from its embodiment it threatens to deprive it of its historical nature and thereby, in fact, also deprive it of its inherent semiotic nature, the ongoing need for a translation between analoguely and digitally coded representations (Hoffmeyer and Emmeche, 1991, see also Etxeberria, 1995). It remains to be seen if the research in artificial life is capable of freeing itself from this over-simplified vision of life and thus contribute to a true semiotisation of our view of nature.
Summarising this discussion we can see that throughout the 20th century the life sciences have been increasingly engaged in what Claus Emmeche has termed a spontaneous semiotics. Spontaneous semiotics implies that 'biological communication is studied not as a phenomenon requiring a special theory or explanatory frame but as a loose accumulation of experiences in different biological disciplines concerning sign-processes in nature' (Emmeche 1995). Biologists accept that communication takes place at all levels of animate nature but generally refrain from reflecting on whether this implies the need for searching any deeper pattern behind this kind of behaviour. This may be because in the end evolution through natural selection is thought to explain the appearance of all such phenomena, which furthermore in each single case can be reduced to molecular mechanics at the level of cells. The reductionist trend in biology here blocks the way for the development of a more theoretical biosemiotics.
There can be no doubt that reductionism in the life sciences has been healthy considered as a research strategy, and it should be pursued as such. But when it comes to theory, it seems that reductionism and the dualism on which it is justified (cf. Searle 1992, 54), has run into serious problems. To explain life as 'nothing-but-interacting-molecules' leaves out a whole dimension of life, which the reductionist research strategy has itself helped digging out, the dimension of semiosis. Accordingly, the aim of biosemiotics could be seen as that of developing biological theory to a level which equals our experimental knowledge about the living sphere of the earth.
Now, as is well known, Prigogine's response to this was to show that traditional theories are insufficient. Prigogine got the Nobel-price for his work on the thermodynamics of irreversible systems and most importantly in this context he showed that in so-called dissipative structures, i.e. systems far from thermodynamic equilibrium, ordered states may sometimes arise spontaneously out of disordered states. Our universe according to Prigogine is inherently creative. Due in large part to this revolution in our understanding of thermodynamics modern cosmology now sees our world as a self-organising place, a view which has perhaps most forcefully been unfolded in the recent work of Stuart Kauffman (Kauffman 1991, 1993).
From the point of view of biology this changed view of the physical basis for organic evolution is of course very encouraging since it implies that organic evolution is no longer a miracle. But it should be remembered that the real task of a unified biology, i.e. a modern synthesis, is to understand how the world became a place for human beings, i.e. how life originated in a non-living world and evolved into all the present day kinds of living entities at all levels of complexity, including human beings. In one end of this scale we have history in the sense of intentional and self-conscious human beings and the cultures they created (or who created them), at the other end we have the kind of self-organising history predicted by the second law of thermodynamics, and what connects the two ends is the subject matter of evolutionary biology.
In this sense biology is a meeting place between physics and the humanities. Biologists, however, consider themselves to be natural scientists and, like Darwin himself, they try to conform to the kind of explanatory strategies developed by physics. As Michael Ruse has shown, Darwin did not need Malthus for inventing his theory, since he had himself, already at the time he read Malthus witnessed and commented on the brutality of nature. What he needed Malthus' laws for was to set forth his theory of natural selection in a lawlike way which he hoped would be acceptable to physics (Ruse 1979, 175).
Seeing biology as part of the natural sciences is congruent of course with Cartesian dualism separating the study of nature from the study of culture. Ironically however, Darwin's work did in principle undermine exactly that idea. If human mind is a product of evolution it cannot be kept independent from the world in which it was born. But if, as a consequence, dualism is skipped, why then should biology be considered so firmly a part of natural science? The evolutionary perspective necessarily opens the borderline questions and tends to leave biology as a confused No-Mans-Land sandwiched between physics and semiotics. I guess this may be the reason why both philosophers and physicist so frequently bypass the muddy regions of the life processes, preferring to explain such things as consciousness or mind directly from physics, whether computers or quanta. The elegance of such short cuttings is only matched by the farfetched nature of their claims.
The semiotisation of nature discussed in the preceding section is profoundly connected to these problems. The advancing edge of biological reduction leaves in its wake a confusing mess of semiotic small talk innocently - or so it is believed - by-passing the need for more formally reductive descriptions. While this may work well in the laboratory, it is definitely unsatisfactory at the level of theoretical biology. If the growing understanding of life processes persistently forces us to adopt a semiotic terminology, and the more so, in fact, the deeper we penetrate into the core dynamics of living systems, then Occhams razor would require us to accept the idea, that semiosis is in fact central to life, and that it is highly unlikely that the extraction of a non-semiotic dynamic at the 'lowest level' is at all possible. This may be a modern formulation of the complementarity relation which Niels Bohr saw between physical analysis and typical biological processes such as maintenance and reproduction (Bohr, 1932) Rather than understanding biology as a separate layer 'between' physics and semiotics, we should then see biology as a science of the interface in which these two sciences meets, an interface in which we study the origin and evolution of sign processes, semiosis.
I have discussed the question of the 'origin of semiosis' elsewhere (Hoffmeyer 1992, 1996, and forthcoming). The essential problem is the following: How could pre-biotic systems acquire the ability of turning differences in their surroundings into distinctions? Even a bacterium is capable of orienting itself (by moving) in a nutritional gradient. The amount of nutrient molecules hitting the receptors of the outer cell membrane changes as the bacterium moves, and this change is registered by the cell, allowing the cell to select the direction in which further movements are done. My claim is that the necessary but sufficient condition for a system to make distinctions in this sense is that it has developed self-reference based on code-duality, i.e. the continued chain of digital-analogue (i.e. DNA-cell) re-interpretations guiding the genealogical descent (Hoffmeyer 1987, Hoffmeyer, 1991). While the origin of such a system requires the creation of a highly structured and chemically very complicated aggregate of macromolecules, there is no reason to doubt that it could not have been created by self-organising processes such as suggested for instance by Weber and Depew (1995). Rod Swenson has pointed out that thermodynamic fields will behave in such a fashion as to get to the final state - minimise the field potential or maximise the entropy - at the fastest possible rate given the constraints ('the law of maximum entropy production' (Swenson, 1989)), and this implies that ‘progressive evolutionary ordering entails the production of increasingly higher ordered states - higher order symmetries of the world itself in its own becoming - and perception-action is the physics at these levels' (Swenson and Turvey 1991, my italics): 'the world is in the order production business, including the business of producing living things and their perception and action capacities, because order produces entropy faster than disorder.’
Semiosis in its most modest form arose in the very process which created the first living systems on earth. From this tender beginning a new evolutionary dynamics was implemented in the world and in the course of time organisms capable of mastering increasingly more sophisticated semiotic interactions developed. Or to state it differently, the semiotic aspects of material processes gradually increased their autonomy thereby creating an ever more sophisticated semiosphere - a semiosphere which finally (after three and a half billion years) had the power to create semiotic systems, such as thoughts and language, which are only in the slightest way dependent on the material world, from which they were ultimately derived (Hoffmeyer 1994, 1996).
The point is, that in the 40ties physics had not yet furnished the means for describing nature in such a way. Only in the last two decades have we got an understanding of thermodynamics and of complex systems dynamics which make an ‘infodynamic’ approach to evolutionary theory possible (as mentioned above). And only now can we see that the capacity for selective processes to unfold in the world has itself evolved (Brooks et. al. 1989). Selection is not an either/or principle separating the human sphere (a sphere of selective processes) from the pre-human sphere as seems to be presupposed by the humanities, neither is selection in the human sense of that word present in pre-human nature as biologists often seem to think. Selection is a concept of more-and-less, it has its own natural history, and that may well be the essence of evolution. Or to state it differently: even historicity has a history (Hoffmeyer, 1995a).
As a consequence the search for a quantitative theory of evolution based at the genetic level, which has been such an obsession for neo-Darwinism ever since the work of Fisher, Haldane and Wright, has been misdirected. As Depew and Weber has expressed it 'natural selection at the level of individuals and the notion of fitness used to measure it, is itself poised on the edge of chaos' (Depew and Weber, 1995): 'The fitness of various sorts of organisms is not necessarily, or even probably, enhanced by superiority in a single trait... In fact, the emergence of the ability to take advantage in resource competitions of an indefinitely number of often infinitesimally small differences creates degrees of freedom, in both the technical and the ordinary senses, well beyond what can be achieved by merely chemical and physical systems. It also creates more variables and interactions among them than can be tracked. It is impossible, then, to reduce the components of fitness to any single language or system of variables' (ibid, 471).
In the terminology of the present paper we can say that when life, and thus natural selection, emerged inside the Earth system we had already passed beyond the secure sphere of physics into the sphere of communication and interpretation. In this sphere the dynamics of history (evolution) changed and began to become individualised, so that each little section of history became unique and henceforward no big formulas could be erected covering the whole process. Organic evolution is narrative rather than lawlike (Gould 1989, Lewontin 1991), and if quantification is wanted, it should be searched not at the level of genetics, but at the level of the constrained thermodynamic system framing organic evolution.
That evolution takes place in the 'ecological theatre', as Evelyn Hutchkinson has expressed it, implies that evolution is always co-evolution. But in the neo-Darwinian tradition co-evolution, with the Red Queen Hypothesis as the standard illustration, is always treated like an arms race problem which implicitly figures evolution as a game against something "out there" (Kampis 1995). While this may of course sometimes be a representative model, it probably in most cases is a caricature.
Let us consider the hare-fox situation recently discussed by Anthony Holley (Holley 1993). A brown hare can run almost 50 per cent faster than a fox, but when it spots a fox approaching, it stands bolt upright and signals its presence (with ears erect and the ventral white fur clearly visible), instead of fleeing. After 10 years and 5000 hours of observation Holley concluded that this behaviour is energy saving: if a fox knows it has been seen, it will not bother to give chase, so saving the hare the effort of running. Holley rejects the alternative explanation, that the hares just want to better monitor the movements of their predators, partly because the behaviour does in fact not help them to see the fox more clearly, and partly because they do not react the same way to dogs. While a fox depends on stealth or ambush to catch a hare, the dog can run faster and it would therefore be counterproductive for a hare to signal its presence.
This situation exemplifies a way of interaction which I have termed semetic interaction (from gr. semeion = sign, etos = habit), i.e. that one species' habits are interpreted as signs releasing other habits in individuals from another (or the same) species (Hoffmeyer 1994b ,1995b): The hare 'knows' that the fox has the habit of not chasing it if spotted. Thus it develops the habit of showing the fox it has become spotted. Whether this habit has become fixed in the genomic set-up of the hare or whether it is based mostly on experience is probably not known, but it doesn't matter much.
The point is that organisms not only belong to ecological niches, they are always also bound to a semiotic niche, i.e. they will have to master a set of signs of visual, acoustic, olfactory, tactile and chemical origin in order to survive. And it is entirely possible that the semiotic demands to populations are often a decisive challenge to success. Ecosystem dynamics, therefore, shall have to include a proper understanding of the semiotic networks operative in ecosystems (Hoffmeyer 1994a).
It should be noticed that the fox profits from this communication as well since at least it spares the time and effort of trying to sneak upon the hare. So, this is actually a kind of mutualism, the whole situation presupposes the existence of a shared interpretative universe or 'motif', we might term it an eco-semiotic discourse structure (with a little help from Michel Foucault's concept 'discours', which very briefly stated refers to the symbolic order relating human subjects to a common world (Foucault 1970, Cooper 1981)). How much of this kind of semiotic co-operation goes on in nature? Probably we have only seen the beginning of this kind of studies, and it would be my guess that our present knowledge gives us only a small glimpse of an nearly inexhaustible stock of smart semiotic interaction patterns taking place at all levels of complexity from cells and tissues inside the bodies and up to the level of ecosystems.
If this is so, one might further speculate that evolution is perhaps as much constrained by the existence of these eco-semiotic discourse structures as it is by developmental constraints. While most biologists suppose that symbiotic mutualism is an exceptional case of no general importance for evolutionary theory, semiotic mutualism involving a delicate balance of interactions between many species might well be widespread. And in such cases, the fitness of any changed behaviour in a species would depend on the whole semiotic system, i.e. the organism-environment borderline would tend to be dissolved. A new integrative level intermediate between the species and the ecosystem would have to be considered: The levele of the eco-semiotic discourse structure. This situation is especially interesting in cases where experience and learning enters the interactive pattern, which might often be the case in mammals or birds. In such cases learning would in a way have subsumed the evolutionary process (as it is the case in human culture), and conversely one might speculate whether a relatively autonomous eco-semiotic discourse structure is not exactly what would be needed for learning to evolve in the first place.
The gist of this reflection is, I suppose, that evolution does not just maximise complexity or information content (whatever that is) but rather it maximises the sophistication of semiotic interactions, i.e. semiotic freedom (Hoffmeyer 1992). And to the extent evolution favours the establishment of refined semiotic interaction patterns between species, it will also tend to open the way for a multitude of physical interactions between species. In this perspective symbiotic relations are not to be considered just funny accidents, rather they constitute a systematically occurring phenomenon in the semiosphere (cf. Salthe 1993, chp. 6).
All this indicates that there is an aspect of play in the evolutionary process, an aspect which has been more or less shadowed out by the one-eyed focus on selection. Play according to my dictionary is an activity which carries its purpose in itself. "What is characteristic of 'play'" writes Gregory Bateson "is that this is a name for contexts in which the constituent acts have a different sort of relevance or organisation from that which they would have had in non-play" (Bateson 1979, 139). Bateson also suggests the definition of play as "the establishment and exploration of relationship" as opposed to ritual: "the affirmation of relationship" (ibid 151). Thus, to the extent nature is engaged in an open ended or non settled exploration of relationships between systems at many levels of complexity, nature does in fact exhibit play like behaviour, and it will be as legitimate to talk about 'natural play' as it is to talk about 'natural selection'. Selection acts to 'settle things', i.e. to fix behaviours, morphologies or genetic set-ups, thereby stopping the play but also allowing for the beginning of new plays. Thus, for instance, more than 50 million years ago a particular ant species began interacting with a kind of fungus and natural selection finally settled this as a new habit of growing fungus. Natural play, however, continued exploring this newly created semetic interaction pattern or 'eco-semiotic motif' since all the 200 ant-growing species now existing have evolved from this single ant species. With few exceptions they all grow fungi from the same family, Lepiotaceae, but exceptions are found. The higher forms of ants have now become so specialised that they cannot survive without exactly the right variety fungus (New Scientist 17/12 94, 15), so here natural selection may finally have obtained a total crystallisation of the relations from the open form of play to the closed form of ritual.
In most cases studied the relations between the interacting organisms is, as in this case, based on a heavy physical dependence (food, protection or the like). But in addition to such examples there are probably all sorts of cases in which one organism uses regularities exhibited by other organisms simply as cues (for orientation, flight, shelter, or whatever) in the same way abiotic factors often are important cues in the life of animals (as e.g. when migratory birds find their way by reading the configuration of stars).
Obviously, increasing semiotic freedom will tend to push the influence of selective forces to higher levels: the more there is of inter-species semiotic interaction the more will the ‘selective aspect’ of evolution be loosened at that level, and the more dominating will be the ‘play aspect’. This is because a rich semiotic interaction pattern produce fitness ambiguity. When organisms are bound up in a web of complex semiotic relations any newly developed property or behaviour can potentially be counteracted or integrated in many ways. The number of possible solutions for selection to scrutinise, and the subtlety of the communicational interactions, will tend to produce a no-win situation. As a result selection cannot really ‘measure’ the stakes of single players (individuals, demes, or species) in the game, but it could still influence the choice of the game itself. Plays, not players, are selected for.
Accordingly I have suggested that in stead of genetic fitness, evolutionary biology should try to develop a concept of semiotic fitness (Hoffmeyer 1995a) After all, fitness depends on a relation, something can be fit only in a given context. Genes may be fit only under certain environmental conditions, or environments might perhaps be said to be fit in the sense that their self-sustaining dynamic capacity has been adapted to the actual genotype resources offered to them. But if genotypes and envirotypes (Odling-Smee and Patten 1994) reciprocally constitute the context on which fitness should be measured, it seems we should rather talk about the fit in its relational entirety, that is as a semiotic capacity. The evolutionarily relevant fitness concept, semiotic fitness, should ideally measure the semiotic competence or success of natural systems in managing the genotype-envirotype translation processes. The optimisation of semiotic fitness results in the continuing growth in the depth of interpretative patterns accessible to life. And this is the nearest thing we can come, I guess, to defining what should be meant by an increasing 'depth of meaning' at the level of biology.
Our ideas of speciation might profit from taking the semiotic dimension of intraspecific interactions into account. Paterson indirectly did so in formulating his theory of speciation through mate recognition. (Paterson 1993). From a semiotic point of view, however, the idea of mate recognition seems to be a little too narrowly conceived. Recognition not only of mates, but also of a multitude of other cues in the environment, might influence the reproductive pattern in such a way as to create isolation. Thus sympatric speciation - which for many reasons seems to be the more attractive model, if only one could find a plausible mechanism - might be obtained by a number of purely semiotic barriers. So semiotics might even hold the clue to this most central of Darwinian events: the origin of new species.
But even the process of speciation does not necessarily hold the key to macro evolutionary development. Morphological trajectories encompassing a number of successive lineages may well require explanation at an even higher level, as suggested by Stanley Salthe, who sees the perpetual unfolding of developmental trajectories, from inception and immaturity through maturity to senescence as the general pattern underlying the formation of high-level trajectories (Salthe 1993). If this is the case morphological trajectories are effectively uncoupled not only from speciation but from adaptation as well .
While it may be true that the 'synthesis' actually at the time furnished a relatively unified perspective to these different branches of biology it is now obvious that important areas of the life sciences are not included in this unification. The semiotic creativity of biological systems at all levels of complexity is systematically excluded form the explanatory universe of the 'synthesis'. As already noted this is a paradoxical situation, because the most central concept of the 'synthesis', the concept of 'selection', is quite simply meaningless outside a semiotic context.
Darwin was right in seeing selection as the central process in animate nature, but for more than hundred years Darwinists have resisted taking the full consequence of this insight. It is now necessary to take this consequence and admit the obvious: That selective processes presupposes interpretations (with the implied possibility of misinterpretation). Thus, to the extent selection is a natural process, semiosis is a natural process - semiosis goes on all the time and at all levels of the biosphere. It may be feared that such a position will put biology outside the safe range of natural science, since interpretation seems to presuppose the existence of some kind of subject-ness. This risk, however, must be confronted through a thorough analysis of the implications, rather than evaded by repression.
The idea of seeing semiosis as a unifying concept in the study of life is often met with charges of vitalism. In fact I think on the contrary that the strategy of repressing the semiotic dimension of life is exactly what nourishes the continual revival of vitalistic notions. No vital principles are of course invoked in a biosemiotic understanding of life. Biosemiotics confronts the same ontological problem as does traditional biology: The problem of explaining how coding surfaces could arise in lifeless nature. As already mentioned I have confronted this problem elsewhere (Hoffmeyer and Emmeche 1991, Hoffmeyer 1992), and I see no insurmountable difficulty in explaining it inside the universe of known physical principles. The difference between biosemiotics and biology rather has to do with the consequences to be drawn from the fact of coding. According to the biosemiotic conception life was from the very beginning suspended in a universe of signification, and though the internal structure of cells or organisms is probably describable in purely biochemical terms, this will not give us a true understanding of such structures, since they were developed through a period of billions of years under the guiding logic of semiotic interactions. The semiotic ordering (through spans of evolutionary history) of chemistry holds the key to the function of this chemistry. In this sense, and only in this sense, is life an irreducible phenomenon.
A modern unification of biology therefore has to be based on the fundamentally semiotic nature of life.