Salikoko Mufwene on the cart before the horse:

I was surprised that Salikoko Mufwene didn’t get the gist of the co-evolution logic, and simply re-iterated the brain-changes-first mutation-leads-the-way logic that has for so long dominated and impeded progress in the study of human evolution. Hopefully few professional evolutionary biologists still cling to this simplification, even if the evodevo perspective hasn’t yet found its way into introductory textbooks and popular accounts of human evolution. Working from this perspective he appears to fear that this is “an adaptive/exaptive perspective that in some ways conflicts with the language that he uses to explain it” in which I postulate function that is present “anterior to the state of the hominin brain that could use it.” Not so. As I tried to make clear in my introductory essay, functional plasticity is the critical missing element. Ask yourself, did we need to have a special music-mutation before we developed musical ability and appreciation or a literacy mutation before reading and writing became possible. Indeed, there has not been brain specialization for these functions, and so from a Darwinian perspective, they are probably “value-added” side-effects of the flexibility of our evolved cognitive specializations.

I obviously assume that “hominins had always been able to communicate”—indeed, communication is ubiquitous in the animal kingdom, it just isn’t symbolic or linguistic nor even a little bit, as Bickerton and other commentators are also quick to point out. In suggesting that “the hominin ability to think and solve problems differently from other primates seems to have preceded the emergence of “symbolic language” itself” we are left with two things to explain: what selected for that prior adaptation in our lineage alone, and how could those special abilities have been so well suited to this otherwise anomalous adaptation, language? The simple exaptation argument for was well criticized by Steve Pinker over a decade ago, pointing out that exapted functions are inevitably poorly suited to the new function and only a fraction of the prior adaptive complexity is likely to transfer. So to argue that this new function “emerged from the interactions of modules” begs the question that relaxation offers a partial answer to (without postulating modularity, only relative functional autonomy). The missing term here is synergy. And the mystery I address is precisely how a novel functional synergy could emerge, given that all contributing component processes must be reciprocally interdependent for that function to emerge. In case the logic of this mechanism is difficult to follow in such a short essay, I have provided a much more elaborate account with many additional examples of these sorts of processes in Deacon (2009). It’s time we stop with the 2% magic mutation and hopeful monster scenarios.

Liane Gabora on creativity and drift:

Liane Gabora’s efforts to dig beneath the superficial details of creative processes of all kinds follows a trail that should also be valuable for the cognitive difference questions pertaining to the neurological adaptations that support our unprecedented ease at communicating and thinking with symbols. We are on the same track here and ultimately there will probably be a convergence between the ideas of Turner, Gabora, and myself on this issue.

Gabora is right to point out that the way I caricatured the concept of “drift” in my essay was incomplete and even somewhat misleading. Although drift is characterized by an increased influence of chance factors over selection, it is not necessarily, and indeed seldom, a relaxation effect. Wright was emphasizing a different source of non-selection effects. Thus, due to sexual reproduction and recombination in small genetically isolated populations, simply the random shuffling of alleles from generation to generation can cause some to go to fixation and others to go to extinction, by the luck of the draw, so to speak. Relaxation effects are also by definition non-selection effects but increase allelic variability irrespective of fixation or extinction effects of drift. So this is more an effect analogous to neutrality (though in a more-or-less sense), and is focused on mutational variety whereas drift is focused on the higher level of allele distributions within a population.

Ajit Varki on anthropogeny:

I am glad that Ajit Varki had an opportunity to offer access to his recently published paper. He presents precisely the sort of genetic approach that can detect relaxation effects in the human genome, and provides some interesting data that is consistent with this hypothesis. Specifically, it is suggestive of a general loosening of constraints on the genome, not only at the level of many loss-of-function mutations and deletions, but also at the level of chromosomal variability. More importantly, he has been the mastermind behind an invaluable resource on human evolution, gathering the theoretical and empirical contributions of a wide network of experts struggling to understand what he describes as “anthropogeny”—the processes that have shaped our uniqueness as a species. It is called CARTA, and many of its resources should be generally available on the web in the very near future.

Sue Savage-Rumbaugh on clinging, epigenesis, and the gray divide:

Sue makes an important point when she boldly states that “the ‘ground zero’ question does not apply to whether apes have language ability – they do.” I am often assumed to be arguing that the transition to symbol use that here has been dubbed ‘ground zero’ is an all-or-nothing discontinuity. In fact, my argument depends on Sue’s being right, though with some qualification. Bears can be trained to roller skate and parrots can be trained to produce appropriate English answers to questions about objects in their environment (as Irene Pepperberg demonstrated with Alex the parrot) even if these abilities never evolved, or ever could evolve, in the wild. With appropriate support, I suspect that many species can achieve some level of symbolic ability. The difference is not the presence or absence of some special symbolic neural module, but the capacity to assemble the complex mnemonic system upon which even simple symbolic reference requires, and this can be significantly aided by external support.

Symbolic reference makes unusual demands on cognition, but as Sue has shown, when some of these demands are externally supported (as with a human symbolic cultural context) chimpanzees and bonobos appear to be able to join the game, at least at a minimal level (though Sue would probably argue that it is more than minimal). The evolutionary question is larger than this, however. I assume that our australopithecine and early hominin ancestors were at least as cognitively capable as our sister ape species in their ability to acquire symbolic abilities. But this is not sufficient. For symbolic communication to be a sustainable socially transmitted adaptation, this supportive context must also have been provided and maintained. For this reason I remain skeptical of Sue’s bet that symbolic communication is more widespread among apes in the wild than just in human laboratory contexts. The co-evolutionary ratchet that has honed both our symbol-learning adaptations and also the symbolic-culture transmission adaptations that guarantee the presence of a supportive context, doesn’t appear to have been initiated in any other animal lineage. If it had, I believe the social and behavioral consequences would be easily recognized because of their divergence from other forms of communication. Of course, if we don’t know what to look for, we may miss it, especially if it has only reached a very minimal stage of evolution.

In conclusion, Sue is probably right that monkeys are really at ‘ground zero’ if that means incapable of symbolic cognition even with extensive support, but for me the hominid ‘ground zero’ was the point at which the co-evolutionary ratchet involving both the cognitive capacity, developmental flexibility (which Sue also points to), and the sufficiently reliable social context could take off. The error, which she highlights, is forgetting that adaptation is always to be understood in context, and the boundary between what is inside and outside is porous, especially during early development. This is the essence of the co-evolutionary perspective.

Givón on evolution, genes, and flexibility:

Let me preface my remarks by noting that Tom Givón is my model for a linguist who has taken seriously the entire range of topics necessary to understand language; including neurology, development, evolutionary biology, social psychology, and semiotic theory. I only wish more of our colleagues would recognize that the proper study of language is not language alone. That said, none of us involved in this project can be experts in all relevant areas, and I am always enlightened by what Tom says about linguistics. Nevertheless we do differ on several points, especially those regarding the evolution and genetics of language and the brain.

I previously responded to certain of Tom Givón’s arguments against a role for relaxation of selection in the evolution of language, so I won’t reiterate those remarks here, except to point out that those features he cites as the “innovative vanguard of adaptive selection” are precisely those that will be most sensitive to relaxed selection. And this isn’t merely armchair speculation. Not only can the effects of relaxed selection be studied in the Finch case, but there are many other empirical exemplars available to study as well, especially involving domestication and founder effects. And as Varki (above) indicates, we are beginning to accumulate evidence for its genetic signature as well—even in humans.

I was slightly more troubled by Tom’s repeating some evolutionary speculations (that still pass for established fact in certain texts) most of which reflect quasi-recapitulationist or progressivist conceptions of brain evolution. For example, he takes as given that “Older evolved systems exhibit more within-species uniformity, are more fully automated at birth, and are less sensitive to epigenesis, maturation and learning.” He adds that “The progression from old (‘reptile’) brain to mid-brain to cortex is a terrific example of this evolutionary trend, with decreased genetic specification, increased phenotypic and behavioral variability, and increased maturation-and-learning sensitivity.” The triune brain of Paul Mclean was a useful heuristic but it is no more than that. The telencephalon is as old as the mesencephalon and the homeotic genes that determine the major divisions of the brain have changed minimally in their structure or regional expression throughout vertebrate evolution. Descent with modification is the rule, not addition. Even cerebral cortex, which is distinctively mammalian, has now been identified with non-mammalian telencephalic homologues.

There are indeed consistent differences in plasticity and structural-functional variability that distinguish, say, medulla from cerebral cortex; but these are not the result of relative recency of their evolution. Most of these claims are not critical to most of his points, and even when he says that “…the core neurological sub-systems that underlie language processing arose much earlier and still perform many of their pre-linguistic functions” he is actually consistent with a descent-with-modification view rather than an addition view (though some of his genetic arguments suggest a bias toward the latter; see below).

Although in my introductory essay I did not present a detailed argument against strong genetic-based theories of grammar, I am indeed a critic of this view, and I can see why Tom might have responded with a modest defense of the nativist view, though among linguists he is often a critic of strong nativist claims. In defense of a genetic source for some features of universal grammar he says “Like all good species-specific universals, they surely are genetically coded.” The phrase “genetically coded” is highly loaded. As someone who has spent his career trying to understand the relationship between gene expression and species differences in brain structure, I am highly sensitive to simplistic claims about genes “coding” for certain traits. So while I completely agree that it is beyond doubt that there is a significant naturally selected genetic basis for human language abilities, I am far more wary of trying to draw a gene-to-grammar correlation, just because something is “universal.” There are other explanations for traits that are highly invariant—especially traits subject to so many levels of causal influence and functional constraint. Genes are only one.

Tom’s characterization of humans as “the only species that, overwhelmingly, communicates about displaced reference by transacting declarative and interrogative speech-acts” is an insightful condensation of the functional features that are most distinctive of language functions, and implicitly also involves the issue of cooperative and honest exchange of information that both Wacawicz and Bickerton mention (discussed in more detail below). But while his comparison between hominid and honey bee foraging is worth pursuing in more detail, the range of selection scenarios that fulfill these criteria is not small. One would like additional constraints to help narrow this range.

Givón, Bickerton, and Stjernfelt on arbitrarity of symbols:

In response to a comment made by Frederik Stjernfelt, Derek Bickerton was quick to point out an important fact: that arbitrariness is not the critical defining feature of the transition to symbolic communication in our early ancestry. There is both a terminological dispute and a conceptual dispute implicit here. First, the terminological point. The term ‘symbol’ has come to be used differently in different traditions, and so first we need to be clear what we are talking about. If all that is meant is a mark that need not share any specific quality with its object of reference, then the term has trivial consequences. This gloss of the concept makes it easy to dismiss its importance for evolution, and indeed this simplification has been the motivation for many language origins researchers to imagine that it is syntax that demands explanation. This assumption about the concept of symbol is also reflected in Tom Givón’s comment that “Saying that human communication is ‘symbolic’ is saying relatively little.” The common usage of the “code” analogy also reflects this simplification, and for similar reasons leads to serious theoretical misunderstandings. A code does indeed involve an arbitrary mapping or correspondence relationship, but that is precisely why its reference is opaque and is the basis for encryption. This is because a code is a mapping of a parallel set of sign tokens to a language. So to describe language or any of its attributes, such as the basis for phonology, syntax, or semantics as a code, merely begs the question.

Derek is entirely correct to point out that “Arbitrariness is a property of many animal calls” and that “the assumption that vervet calls “mean” (or at least include) “leopard” is a back-projection of our own language-saturated view of the world.”… “Vervet calls are indexical, not symbolic, as Terry’s book showed.” Thus arbitrariness is a red herring, and should indeed not be held up as a critical defining feature of language. But symbolic reference is not merely arbirariness and conventionality. As Charles Peirce pointed out over a century ago, we must distinguish properties of the sign vehicle (which he terms a representamen), which can include being an arbitrarily defined (i.e. conventional) type of sign vehicle, from properties taken to link it to its object of reference. Thus although current vernacular has habitually termed alphanumeric characters ‘symbols’ this usage ignores any referential relationship, and if not used carefully, in recognition of this shorthand, it can lead to all manner of theoretical confusion. Thus when your computer begins randomly spewing alphanumeric characters onto your screen they are indices of a malfunction, not symbols of anything. And likewise ;-) does not refer symbolically, even though it is composed of conventional tokens as is the term I-beam, though it mixes iconically and symbolically interpreted components. Peirce terms conventional sign vehicle types “legisigns,” and argues that symbols must also employ legisigns, but also that icons and indices can as well. A symbol is, in contrast, doubly conventional. It involves a conventional sign type that is additionally convention-mediated in the way it represents.

Frederik knows this well, as does Tom, though it may not be clear from their remarks. We differ in our interpretations of Peirce, and how to define symbols. Because this may be confusing to readers, I will try to spell out in some detail the difference and explain why I think arbitrarity is a distraction.

Arbitrariness is a negative way of defining symbols. It basically tells us that neither likeness nor correlation is necessary. But this is inadequate, even though it is a common shorthand way of characterizing symbolic reference. All sign relationships include some degree of arbitrarity, because those attributes that are taken as the ground for the sign-object linkage can be chosen from many dimensions. Thus, anything can be treated as iconic or indexical of almost anything else depending on the interpretive process.

For example, with a bit of imagination a face can be discerned on the full moon, or in a cloud formation, and it might even remind you of someone you know. But iconism can also be highly abstract, as in Peirce’s demonstration that a mathematical equation refers iconically, once you know how to discern its symbol-mediated isometry (e.g. between the structure of the equation and a corresponding geometric or dynamical relationship). An equation can be interpreted to be iconic (e.g. of a parabolic trajectory) only, however, if you know how to discern the way that differences in the values or operations directly correspond to differences in the geometric object of reference. Frederik has recently written extensively on this point, so I found his remarks about arbitrarity a bit disappointing.

Indices refer by contiguity in space, time, or substrate. A simple correlation can therefore be the ground for indexical reference. A lipstick smear on a man’s shirt collar can be a troublesome indication to his wife, a urine scent on a branch can be a sexual index to a female lemur, and the mobbing call of a small bird can indicate the present of a raptor. What gets correlated and how (accidental, cultural, evolutionary) is arbitrary, only the fact of correlation is not. Thus, a rat in a Skinner box pressing a bar in response to a bell in order to get a water reward has learned that the bell is an arbitrary index of the state of the apparatus. These states are arbitrarily paired in the experimental design, but that doesn’t make the one a symbol of the other. Repeated pairing—correlation—is, similarly, the basis for the indexicality of a vervet monkey alarm call sound and a type of predator and an appropriate defense activity. In this case, however, the pairing has occurred throughout the recent evolution of vervet monkeys. Other pairings that may have occurred did not also correlate with a sufficient level of survival. This evolutionary correlation is the basis for the innate indexicality of these calls. Elsewhere (Deacon 1997, 2003a) I have argued that innate iconicity and indexicality can evolve by natural selection, as in the above example, but that because of their displacement from intrinsic referential relationships, it is all but impossible for innate symbolic reference to evolve as a biological trait. This is part of the reason that I doubt the evolution of innate grammatical relationships, since they are largely symbolically derived.

Arbitrarity is indeed aided by using convention to mediate the referential relationship, as opposed to some intrinsic sign attribute, since any similarity and correlation relationship involved is, in this case, produced external to the sign-object relationships. But arbitrarity is hardly diagnostic. So when I have used the term symbol I have adhered strictly to the notion of a doubly conventional referential relationship. And so it is the competence to construct this conventional system that mediates the interpretation of the referential relationship that matters and—to use Derek’s challenging image—this is ground zero.

Though I have not had the context to make the argument here, I also agree with Sue Savage-Rumbaugh’s comment that “true symboling and grammar are inextricably intertwined. It is fundamentally impossible to have one without the other.” Once we overcome the tendency to treat symbolic reference as merely arbitrary correlation we can begin to discern the many contributions of the iconic and indexical supports of symbolic reference that have become incorporated into the constraints that define the grammar of language (for the general argument see Deacon 2003b).

Wacewicz and Bickerton on cooperation and altruism:

Consensus points? Slawomir Wacewicz begins his comments by listing four points of consensus that he believes should now be widely accepted, but which were highly contentious or even radical propositions at the time that my book The Symbolic Species was written. If he is correct, then considerable progress has been made in this field since each of these—language as niche construction, brain-language co-evolution, incremental evolution through a protolanguage phase, and a significant phylogenetic age for the origins of language—was first proposed. Indeed, each hypothesis has gained in acceptance due to the theoretical, simulative, and empirical results that have derived from efforts to test them.

He pushes further, though, when he asks “Could your account perhaps be made compatible with some particular explanation of the emergence of altruism/cooperation as manifested in linguistic communication?” This same refrain is echoed by Derek Bickerton when he asks “why should anyone transfer useful information to non-kin?” Derek outlines his own recently articulated scenario, which loosely parallels the one I offered in The Symbolic Species: that foraging for animal remains with stone tools (which began at least 2.4 million years ago) required the evolution of a form of cooperative behavior that could only be maintained by the sharing of “honest” information. I agree with both Wacewicz and Bickerton that the evolution of symbolic communication and extensive cooperative prosocial behavior are necessarily linked. Just a brief reflecting on the astronomical quantity of socially inherited information that characterizes language and culture makes it obvious that it could not be reliably transmitted in a largely competitive selfish context. Its complexity and fidelity of transmission depend on a significant enhancement of prosociality in our species. But, beyond just recognizing this dependence, I believe that this linkage is the result of a co-evolutionary process that also involves a relaxed-selection plus niche-construction logic.

In a paper soon to be published (Hui and Deacon, 2010), we offer a scenario for the evolution of what we describe as social addiction in which we argue that relaxed selection may be a crucial contributor to the evolution of altruistic and other prosocial behavioral tendencies. Recall that in the case of domestication, relaxation of selection can lead to degradation of functional autonomy and that this can increase the options for synergistic interactions. If cooperation is necessary to scavenge carcasses (some members fending off predators/scavengers while others cut off meat, and later share among all including mothers and infants who must stay apart because of the danger of predation), reliance on this strategy itself can relax selection on a variety of traits that would otherwise be necessary to success at non-cooperative foraging.

One uncontroversial example of a relaxation effect was the significant reduction of the teeth and jaw muscles once critical to the ancestral australopithecine adaptation to a vegetarian diet. A half million years after the first appearance of stone tools, Homo habilis had lost this entire complex, including the loss of a specific myosin protein long evolved for the special demands of chewing in mammals. This degeneration effect is not unlike the degradation of the ability to endogenously produce vitamin C that occurred (because loss-of-function mutations of the GULO gene were not selected against) during early anthropoid evolution as a result of the regular incorporation of fruit in the diet. Loss of the ability to process the major food source available to non-cooperators would have selectively favored prosocial adaptations to keep a cooperative social group together because group dissolution would now be costly to all.

Prosociality is more than altruism, however. It involves policing and means of promoting/enforcing egalitarian behavior (e.g. in mate access) as well as sharing of resources and information. The ratchet-like effect by which increased social addiction leads to increased offloading of inherited adaptive information onto social transmission processes leads to increased social addiction would have produced a deep interdependence between the cognitive adaptations for language and prosocial behavior, as both Wacewicz and Bickerton imply. This is what leads me to predict that the language adaptation complex is probably not centered around a built-in grammar so much as a diverse synergistic system of cognitive supports for social learning, social transmission, and reconstructing the thoughts and intentions of others.

Again, let me re-emphasize (since some commentators, e.g. Mufwene, seem to miss the point, see below) that relaxation of selection is not an explanation for adaptation—that requires natural selection—it is rather an important and generally unrecognized precursor to functional reorganization and exaptation in evolution. Like genetic mutation, its consequences are generated irrespective of functional outcome. The point is that the dedifferentiation that inevitably follows from relaxation of selection can be a contributor to the emergence of unprecedented interactions between subsystems that were previously specialized for separate and independent functions. This simply increases the possibility that synergies will spontaneously emerge. Nevertheless, by enabling previously prohibited (by natural selection) interactions between separate adaptive mechanisms, this can expose these previously unavailable interaction-effects to natural selection which can now hone any synergistic consequences. Although I entirely agree with Liegh Van Valen that there can also be direct selection for flexibility, I would argue that this requires a more unusual and persistent context than do relaxation and degradation effects. To put it simply, it takes far more restrictive conditions to drive an adaptation to fixation in a species, than to degrade it.

To conclude:

The many thoughtful responses to this target essay offer no more than a tiny peek into a field of study that has seen an explosion of research interest in the past two decades. They also demonstrate both the diversity of approaches and of fields of study relevant to this topic. The study of the origins and evolution of language is still in its infancy. As a result, as Givón notes, discussing it inevitably opens a can of (speculative) worms. It poses one of the most difficult scientific challenges of our age, but our science has matured to the point where it is no longer just a playground for armchair speculation. To approach this complex mystery with the respect it deserves, however, we must be prepared to give up on simple one trick accounts, innate mentalese, miraculous mutations, increase in general intelligence, and so forth, and embrace its complexity as a semiotic-biological-epigenetic-social phenomenon whose structural features reflect the convergent co-evolutionary interactions of all these levels of causal process. Because of this, language defies evolutionary arguments that fail to account for the co-evolutionary mechanisms operating across these many levels and involving many diverse processes—and not merely natural selection. In this respect, I agree with Mufwene’s characterization of language as an “emergent” phenomenon, though for different reasons. In this respect, studying language origins offers an unprecedented view into the complex circuitous creative processes that have produced nature’s most spectacular masterpieces of design. I thank all who have responded for a lively and challenging dialogue.

References:

Deacon, T. (1990) Fallacies of progression in theories of brain size evolution. International Journal of Primatology 11: 193-236.

Deacon, T. (1997) The Symbolic Species: The Co-evolution of Language and the Brain. W. W. Norton & Co., New York.

Deacon, T. (2003a) Multilevel selection in a complex adaptive system: the problem of language origins. In B. Weber and D. Depew (eds.) Evolution and Learning: The Baldwin Effect Reconsidered. MIT Press, Cambrige, MA, pp. 81-106.

Deacon, T. (2003b) Universal grammar and semiotic constraints. In Language Evolution, M. Christiansen & S. Kirby, eds., Oxford U. Press, pp. 111-139.

Deacon, T. (2005) Language as an emergent function: some radical neurological and evolutionary implications. Theoria 54: 269-286.

Deacon, T. (2009) Relaxed selection and the role of epigenesis in the evolution of language. In Mark S Blumberg, John H Freeman, Scott R Robinson (Eds.), Oxford Handbook of Development Behavioral Neuroscience, Oxford University Press.

Hui, J. and Deacon, T. (2010) The evolution of altruism via social addiction. In Social Brain, Distributed Mind. R. Dunbar, C. Gamble, and J. Gowlett (eds.). Proceedings of the British Academy/Oxford University Press.

Striedter, Georg F. (2004) Principles of Brain Evolution. Sinauer Associates.

An extremely interesting comment came from Sue Savage-Rumbaugh. I feel that a vast majority of researchers in the evolution of language reject her conclusions. However, the idea of giving more prominence to the differences in the developmental trajectories rather than in the ‘raw genetic makeup’ between humans and (other) apes is indeed likely to become more and more influential as research progresses. I am particularly interested in Terrence Deacon’s reply to this post.

A brief comment on ‘drift’. Terry says that “The usual consequence of relaxed selection is genetic drift—increasing the genetic and phenotypic variety of a population by allowing random reassortment of alleles.” However drift, as Wright (1969) defined it, generally decreases variety rather than increasing it. The term ‘drift’ is generally used to refer to refer to changes in the relative frequencies of alleles (forms of a gene) as a statistical byproduct of randomly sampling from a finite population. In other words, because the population is finite, some alleles are not sampled, and therefore eliminated, thereby reducing variety.

Linguistic note: “There is a leopard, run” does NOT correspond to the Subject-Predicate structure of language, because “leopard” is not the subject of “run”.

Nature Reviews Genetics 9, 749-763 (October 2008) Human uniqueness: genome interactions with environment, behaviour and culture http://www.nature.com/nrg/journal/v9/n10/abs/nrg2428.html

suggesting that aspects of human uniqueness arose because of a primate evolutionary trend towards increasing and irreversible dependence on learned behaviors and culture — perhaps relaxing allowable thresholds for large-scale genomic diversity. Examplars of this trend at the two extremes that are mentioned are:

– the lack of genetic fixation of very long-standing hominin behaviors like control of fire

– the loss of many aspects of pre-existing genetically fixed behaviors that are required for optimal mothering: significant in monkeys, worse in apes, worst in humans.

Thus, one explanation for “Wallace’s Conundrum” is the human evolutionary path of offloading critical functions and behaviors from the genome to the phenome, and from the individual to the group.

Not being an expert on language I will not specifically comment further, except to suggest that the evolution of human language abilities may have had a similar trajectory, with only core “innate” aspects now being genetically fixed, and the rest being dependent on input learned behaviors and cultural input from conspecifics.

Ajit Varki, UCSD. http://cmm.ucsd.edu/varki/

Next, an observation. Having been influenced in my youth by Marshall McLuhan’s observation that “the content of a medium is another medium” and later by working with layered network protocols, I instinctively view “communication” as involving multiple layers and try to be careful in tying any discussion to the relevant layer(s). In the present context, I see the bottom layer as being roughly the ability to make and detect audible sounds, the top layer as being natural language as we currently know it, and the intermediate layers as being some assortment of the results of evolutionary steps between the bottom and top layers. The point here isn’t to define the layers, only to suggest that focusing on specific layers might help in minimizing some misunderstandings that I think arose in the discussion. For example, I see Prof Deacon’s essay as mainly focused on higher layers, while some of the comments were more apropos lower layers. Explicitly identifying the layers under consideration might avoid some confusion.

Although he didn’t make it explicit, I think Prof Givón’s comment (which was immensely helpful in getting at least a tenuous grip on the exchanges) essentially addressed this idea, especially the critical point that especially in considering evolutionary history, the timing and relevant considerations may vary considerably depending on the layer being addressed.

Finally, somewhat of an aside. In Susan Blackmore’s interview with Vilayanur Ramachandran (in her book Conversations on Consciousness), he alludes (unfortunately, there are no details) to the more-or-less simultaneous emergence (in his view) of language, consciousness, and the sense of self – which seems reminiscent of Prof Turner’s conceptual blending. I see this as possibly relevant to the present discussion since I am leaning toward a view of consciousness as an emergent epiphenomenon attendant to the brain’s facility for creating an internal virtual “picture” of the neurological correlates to sensory inputs from the organism’s environment, a “picture” that is “viewable” by the virtual “self” that represents the organism in that environment. (The Cartesian Theater denied by Dennett, only here explicitly assumed not to actually exist, so no latent dualism emerges.) The ability to create this virtual “picture” would include the ability to associate the virtually “visible” symbols with objects in the environment, a step toward the required symbol-object association required for language, as noted by several commenters.

Addendum: I see from Ms Savage-Rumbaugh’s just-posted and very interesting comment that the self-language tie may be even closer than that implicit in my “aside”.

Derek Bickerton now pinpoints the issue by saying that “… the very notion of being able to use an arbitrary sign to symbolize entities or actions in the real world is totally alien to the way other animals think.” It is definitely true that the vast human system of symbolic communication is alien to animal semiotics. But that is not the same as claiming there is no semiotic arbitrarity (or convention, or habit) in the animal kingdom at all. Indeed, the admittance of germ-like forms of arbitrarity in animals makes the issue of the “semiotic missing link” between animal and man less steep and forbidding. Bickerton points to animal thinking rather than communication. But in the way higher animal think, a basic arbitrarity resides in their ability to learn. Take good old Pavlovian conditioning – this amounts to learning the arbitrary association between a bell sound and feeding. After such conditioning, the bell now functions as an arbitrary sign for food. In the Peircean terminology, such a sign is definitely a symbol. This is not, of course, to say those dogs by themselves use such symbols to communicate. But it shows that higher animals, capable of ontogenetic learing, has the ability of forming stable, arbitrary symbols by associating events in their surroundings (see the discussion in my Diagrammatology, 2007).

Even further down in the animal kingdom, we find symbols on the species level – even on the interspecies level, such as the yellow-black stripe pattern as a sign for danger in and among insects and their predators. This symbol is, of course, prompted by the existence of insects displaying that pattern and really being poisonous, such as wasps – but during evolution, other, non-poisonous species have adapted by acquiring a similar pattern, protecting them, to some degree, against predators. This is not, of course, a symbol developed nor learned during ontogenetic life like the conditioned symbol – it is rather a phylogenetically evolved symbol emerging during the slow process of combined natural selection of several species in certain ecosystems. But still, the symbol is effective in the life and interaction of individual organisms. And still the symbol is arbitrary – there is no intrinsic or iconic connection between the yellow-black pattern and danger.

This points to the issue that the categorical way of phrasing the issue presupposing arbitrarity is an all-or-none issue is misleading. Rather, arbitrarity and symbolicity come in degrees; many signs are arbitrary in some respects and motivated in others, symbols and icons at the same time. An important aspect of semiotic-cognitive co-evolution is the appearance of ever more arbitrary and interconnected symbols – and finally their appearance also in ontogenetically acquired communication between individuals. The famous vervet monkey warning calls seem to constitute an example of such a simple symbolic communication system.

Thus, on such an account, there is no clear non-symbolic/symbolic borderline between animals and human beings. But this does not in any way invalidate Deacon’s approach – rather, it places the dramatic increase of symbol use in human beings on a basis on which it seems easier to understand how it might emerge in the first place.

Professor Givón adds an important observation to such a scenario: the notion that the vervet monkey calls should not be seen as simple signs, but rather as full-blown propositional speech acts. My guess would be that all efficient animal signs are such holist propositions. This makes it more easily understandable how human propositions may evolve – namely by the internal differentiation of propositional structure, in turn making human propositional stance much more flexible because propositions may now be constructed from different simpler signs – which was not earlier beforehand.

This finally ties in neatly with Deacon’s intuition that grammar – or, at least, central parts of grammar – may have an a priori status. Propositions, even if holist and not-yet differentiated, must at the very least do two things at once. They must 1) indicate the presence of an object, and 2) say something about it. Like “There is a leopard, run!”. This, of course, corresponds to the basic S-P or noun-verb structure of grammar which seems to be present as aspects of the symbol already in biosemiotic propositions – even if of course not present in the sense of explicit grammatical parts of the proposition.

Such a scenario makes animal semiotics and cognition much simpler than human language and cognition – but not because animals use simpler signs which humans later compose into more complicated patterns. Rather because animals use signs which are later subdivided, differentiated, and made plastic and controllable by human beings. Such a scenario thereby has the force that the animal-human transition becomes not less dramatic – but more continuous.

More important for the current debate however, is the fact that this debate began before science achieved the ability to rapidly sequence the entire genome and to follow genes across generations. Such new data is challenging the ground rules of evolutionary theory at its core. We no longer need infer that genes have changed, because anatomy and behavior have changed. We can look and see if genes have changed and what genes have changed. We now know the following things.

a) The biggest genetic differences between apes and human beings lie in genes that code for immunity not those that code for ‘intelligence’ or language in any simple sense, or anatomy. Apes and humans are true sibling species.

b) The onset of FLUENT speech could indeed have been a sudden genetic event. This is different from the onset of speech itself, or the linkage of speech to a wide array of complex cognitive processes.

c) Epigenetic markers are more likely than genes themselves to account for the behavioral changes we associate with language, thus making the ape to human transition more of a cultural transformation than a biological transformation.

d) Genetic activation profiles during prenatal and postnatal development, as a function of culture, can manifest differently in different environments, with major life changing consequences.
The basic question of whether evolutionary theory can account for language must now be understood on the basis of this new knowledge.

Ape rearing requires clinging, human rearing does not. Thus the ape and human developmental trajectories that are built from birth forward, produce different kinds of beings and very different epigenetic profiles. This one difference, clinging, affects the tendency toward bipedalism, toward free vocalization, and toward object use and manufacture.

When bonobo infants are reared in an environment which decreases or eliminates the constant need to cling to the mother, their hands and eyes become free from birth to engage in a variety of object manipulatory activities. This allows the brain to construct eye/hand/mouth/object manipulatory systems that are co-ordinated in ways that follow the pattern of human infants. The need to cling inhibits this and channels the neurological development of eye/hand coordination in a ‘non-relaxed’ developmental manner. This phenomenon is analogous to Deacon’s ‘relaxation’ hypothesis, but it is the culture which is the relaxing constraint, not the genes. Not only do patterns of eye/hand coordination change in striking ways with human rearing, the vocal system becomes relaxed as well. This is not because it becomes free of any genetic constraint. It is freed because of a decrease in the risk of predation. Humans infants living in stable dwellings are far less likely to be attacked than bonobo infants. When an bonobo infant, in an arboreal a world, gets very far away, makes very much noise or gets interested in playing with objects rather than watching its mother and rushing to her before she moves, its chances of survival decrease markedly. If a bonobo mother puts a very young baby down, it is immediately subject to predation. Human reared bonobo infants face no such pressure and are free, because of human culture, to follow the developmental trajectory of the human infant.

As they do so the plasticity of their nervous systems allows them to process and comprehend human speech, both symbols and syntax. Thus it becomes clear that the ‘ground zero’ question does not apply to whether apes have language ability – they do. The question is what is the cultural trajectory required to facilitate a human language. The answer is that the required cultural trajectory is obviously a human one. Were a human child to be reared along an ape cultural trajectory, even though it had a human brain, it would not manifest a human language, even though it possessed a human brain and would, like free-ranging apes, manifest the ability to communicate symbolic meaning with intentionality.

While some linguists continue to quibble about whether what Kanzi has demonstrated is really exactly human language, this debate is really no longer relevant. Kanzi clearly has acquired sufficient language ability to indicate that the human rearing trajectory is the key ingredient in the emergence of human language. In this vein, it is essential to note that Kanzi did not have a uniquely human rearing – he was reared in a Pan/Homo culture. Had Kanzi been reared with a uniquely human trajectory, his human language capacity would perhaps have become sufficiently well developed that not only would he be producing vocal approximations of human words and sentences, but quite clear ones. (For those readers interested in seeing what Kanzi and family have accomplished, go to Kanzi.bvu.edu)

Kanzi is a ‘first generation’ attempt to determine what happens when scientific investigation pushes the cultural envelope toward the human trajectory. Because Kanzi was co-reared by bonobos and humans, his cultural envelope was also constantly pulled toward the bonobo norm by Matata. It is not possible to know how far Kanzi could have gone had this not been the case. The participants of this debate seem to assume that the data is in with regard to what apes can do. Such is not the case. Only a few apes have been reared on a truly human trajectory from birth (Gua and Vickie), and none of them stayed on an exclusively human trajectory, with an extended human family, into adulthood. Moreover, neither was provided an alternative symbol system to overcome the differences between ape phonemes and human phonemes. The so called ‘language failures’ of Nim and Washoe, represent attempts (unlike Gua and Vickie) to focus on raising apes as ‘subjects’. These projects did not plan to extend the true ‘expectancies of humanness’ to these apes. The apes were experimental entities, not family members. One would thus predicate that these apes would fail, because of a lack of sufficient cultural inclusion to allow the cultural bias to imprint itself upon their developing neurological system.

The fact that Kanzi and family have acquired significant components of human language does not eliminate the ‘ground zero’ issue raised by Bickerton, it merely pushes the question further down the phylogenetic scale. Apes are sibling species with humanity. There are no real fossil apes between 5 million years ago and today. Chimpanzees have 48 chromosomes, humans 46. The human chromosome number two is formed by combining two of theirs — or alternatively, the human chromosome number two broke, resulting in their 48 chromosomes. This could have happened at anytime. It could even happen today. In vast areas of our genome, for example those genes dedicated to bodily odor, the difference between various human beings exceeds those between apes and humans. Where we really differ genetically is where it matters most. We differ in immunity. Because we live in radically different environments, we require different immunological profiles. Unless, of course, apes were to be reared in human cultures. We should then expect to begin to see changes in immunity profiles.

But monkeys are not siblings to our species. Monkeys are not self-aware, nor are they self-reflective in the sense that apes are. There has been no indication that monkeys would acquire language if reared in a human world, though many have been so reared. Without a concept of the self as a knowing, free-willed causal agent, language makes no sense. Monkeys can solve symbolic tasks and monkeys can utilize sounds to inform others of predators, but they do not manifest self-cognizant, self-reflexive intentional actions. Apes and humans do.

This self-reflexiveness, which becomes manifest in the grammar of our language, enabled humanity to become the symbolizing species to which Deacon refers. Apes have this potential as well, when reared on a human developmental trajectory. Monkeys appear to remain at ground zero. This behavioral discontinuity between living species of monkeys and ourselves aligns with the genetic data. Trying to uphold a similar distinction between humans and apes is contrary to all genetic evidence to date.

It is probable that language of a different form than human language will be found in free-ranging apes. It is probable that monkeys will be found to have a far larger array of sounds than we now know and that many of them will have multiple meanings depending upon how they are embedded in the context. They may even combine sounds according to some rules. What does not seem likely is that monkeys will begin to talk and think in a self-reflexive manner.

We now know that various familial lines seem to be biologically distinct at very basic levels. Recent work has revealed that during embryogenesis, epigenetic markers are stripped off at various points before implantation. These timing points differ across the basic mammalian lines. Therefore all mammalian lines are not transmitting epigenetic markers in the same way, as would be predicted by evolutionary theory. The new knowledge of embryogenetic transmission of epigenetic markers is already requiring many to rethink their basic views of how evolution operates. With the coming advances in these fields we will gain a clearer understanding of what has truly happened, at the genetic and epigenetic level, between humans and apes. As we do, the current era speculation and debate will fade under the weight of the genetic facts.