'Language' 'Evolution' = Egghead Carnival @JASSS

Amy Perfors: Simulated Evolution of Language: "First, and most importantly, there is increasing indication that Chomsky's original ``poverty of the stimulus'' theory does not adequately describe the situation confronted by children learning language. For instance, he pointed to the absence of negative evidence as support for the idea that children had to have some innate grammar telling them what was not allowed. Yet, while overt correction does seem to be scarce, there is a consistent indication of parents implicitly ``correcting'' by correctly using a phrase immediately following an instance when the child misused it." (Demetras et. al. 1986; Marcus 1993, among others) More importantly, children often pick up on this and incorporate it into their grammar right away, indicating that they are extremely sensitive to such correction.

3.13

More strikingly, children are incredibly well attuned to the statistical properties of their parent's speech. (Saffran et. al. 1997; De Villiers 1985) ... Pinker (1994) These two facts combined together suggest that a domain- general strategy that makes few assumptions about the innate capacities of the brain ... [boring!]

3.14

Other evidence strongly indicates that children pay more attention to some words than others, learning these ``model words'' piece-by-piece rather than generalizing rules from few bits of data. (Tomasello 1992; Ninio 1999) ...

4.2

Any scientist hoping to explain language evolution finds herself needing to explain two main ``jumps'' in evolution: the first usage of words as symbols, and the first usage of what we might call grammar. For clarity, I will refer to these issues as the question of the ``Evolution of Communication'' and the ``Evolution of Syntax,'' respectively.

{absurd 4.3}

For each concern, scientists must determine what counts as good evidence and by what standard theories should be judged. The difficulty in doing this is twofold. For one thing, the evolution of language as we know it occurred only once in history; thus, it is impossible to either compare language evolution in humans to language evolution in others, or to determine what characteristics of our language are accidents of history and what are necessary parts of any communicative system. The other difficulty is related to the scarcity of evidence available regarding the one evolutionary path that did happen. ``Language'' doesn't fossilize, and since many interesting developments in the evolution of language occurred so long ago, direct evidence of those developments is outside of our grasp. As it is, scientists must draw huge inferences from the existence of few artifacts and occasional bones -- a process that is fraught with potential error.

4.9

What does this have to do with language? Quite simply, the lexicon reflects this hierarchical structuring. Every word in every language can not only be defined in terms of other words in the same language, but exists as part of a sort of ``universal filing system'' that allows for rapid retrieval of any concept. Bickerton suggests that this filing system, as it were, was achieved before the emergence of language (or at least before the emergence of language much beyond what we see in animals today). Thus, meaning was originally based on our functional interaction with other creatures; only as our general cognitive abilities grew strong enough did we gain the skills to arbitrarily associate symbols with those basic meanings. Eventually, of course, language was used to generate its own concepts (like unicorn), but initially, language merely labeled these protoconcepts that were already in our heads as part of our PRS.

4.13

The other reason for believing that full language did not exist until relatively recently is that there is little evidence in the fossil record prior to the beginning of the Upper Paleolithic (100,000 to 40,000 years ago) for the sorts of behavior presumably facilitated by full language. (Johanson & Edgar 1996; Lewin 1993) Although our ancestors before then had begun to make stone tools and conquer fire, there was little evidence of innovation, imagination, or abstract representation until that point. The Upper Paleolithic saw an explosion of styles and techniques of stone tool making, invention of other weapons such as the crossbow, bone tools, art, carving, evidence of burial, and regional styles suggesting cultural transmission. This sudden change is indicative of the emergence of full language in the Upper Paleolithic, preceded by something language-like but far less powerful (like protolanguage), as Bickerton suggests.

4.17

However, there is one glaring drawback to Bickerton's theory. The problem with an explanation relying on a sudden genetic mutation (or even a slightly more probable fortuitous recombination) is that on many levels it is no explanation at all. It takes an unsolved problem in linguistics (the emergence of syntax) and answers it by moving it to an unsolved problem in biology (the nature of the mutation). Still unknown is what precisely such a mutation entailed, how one fortuitous mutation could be responsible for such a complex phenomenon as syntax, and how such a mutation was initially adaptive given that other individuals, not having it, could not understand any grammaticalization that might occur.

The second criterion, demonstrating that there are no processes other than biological natural selection that can explain the complexity of natural language, entails more than may appear on first glance. Pinker and Bloom must first demonstrate that processes not relating to natural selection as well as processes related to non-biological natural selection are both inadequate to explain this complexity. And finally they must demonstrate that biological natural selection can explain it in a plausible way.

4.27 {FUD'fest 4.27 who 'pays' for this drivel?}

If the mind is indeed a multipurposive learning device then Pinker and Bloom suggest that it certainly must have been overadapted for its purpose before language emerged. They point out that our hominid ancestors faced other tasks like hunting, gathering, finding mates, avoiding predators, etc, that were far easier than language comprehension (with its reliance on memory, recursivity, and compositionality, among other things). It is unreasonable to assume that general intellectual capacity would evolve far beyond what was necessary before being coopted for language.

4.32

Another problem with the Pinker/Bloom analysis is that it relies on what Richard Dawkins terms the Argument from Personal Incredulity. [barfy gibberish]

4.34

One of the most plausible arguments to the viewpoint that language is the product of biologically-based natural selection is the idea that rather than the brain adapting over time, language itself adapted. (Deacon 1997) The basic idea is that language is a human artifact -- akin to Dawkin's ideational units or ``memes'' - that competes with fellow memes for host minds. Linguistic variants compete among each other for representation in people's minds. Those variants that are most easily learned by humans will be most successful, and will spread. Over time, linguistic universals will emerge -- but they will have emerged in response to the already-existing universal biases inherent in the structure of human intelligence. Thus, there is nothing language-specific in this learning bias; languages are learnable because they have evolved to be learnable, not because we evolved to learn them. In fact, Deacon proposes that languages have evolved to be easily learnable by a specific learning procedure that is initially constrained by working memory deficiencies and gradually overcomes them. (1997

8.16

John Batali (1994) did a similar simulation to Kirby and Hurford, except that his involved the initial settings of neural networks. He discovered that in order for the neural networks to correctly recognize context-free languages, they had to begin with properly initialized connection weights (which could be set by prior evolution). Yet this should not be taken as evidence supporting a rigidly nativist approach: all that seems to be required is a general-purpose learning mechanism. To understand how Batali arrives at this conclusion, we must first take a look at some of the details of his experiment.

8.23

Yet, as Batali cautions us, we cannot conclude from this experiment that this is an instance of language-specific innateness. Since the individuals involved here are neural networks, it is unclear whether their initial settings are representative of language-specific learning mechanisms, or just general purpose ones. That is, any ``rules'' the network might possess are represented only implicitly in the weights of the network -- so it is very hard to conclude that these weights represent language-specific rules at all.

9.7

Briscoe's work incorporates a great deal of experimentation including issues such as how the population makeup (heterogeneity, migrations, etc) affect acquisition (1998, 1999a, 1999b), how creolization may be explained using a parameter-setting approach (1999b), how an LAD and language might coevolve rather than be treated as separable processes (1998, 1999a), and how constraints on learnability, expressibility, and interpretability drive language evolution (1998). These are all important and interesting problems, but many fall out of the bounds of what is directly relevant to what we are studying here.

10.17

Michael Oliphant (1996) asks the exact same question, but his agents are bit-strings using genetic algorithms that are made up of a two-bit transmission system and a two-bit reception system. The transmission system produces a one-bit symbol based upon a one-bit environmental state (so the system `01' might produce a 1 when in environmental state 0). Similarly, the reception system produces a one-bit response based upon the one-bit symbol sent by the speaker. As in Batali's work, the fitness function discriminates between transmission and reception systems: fitness is based upon only the receiver's average communicative success. In other words, if a speaker and listener communicate successfully, the receiver gets rewarded; otherwise, it gets punished. Nothing happens to the speaker either way. Again, this is done in order to simulate the perceived lack of reward for speaking in the real world.

10.20

The parallels between this situation and the Prisoner's Dilemma are striking, so Oliphant (1996) pursued the analogy further by simulating variants of the scenario that are analogous to strategies successful in promoting altruistic behavior in the typical Prisoner's Dilemma. In one such variant, individuals are given a three-round history allowing them to document the actions of themselves and their opponents so that they know who is trustworthy. They are also given a means by which to alter their behavior based on the past behavior of the opponent. The idea, of course, is that individuals who constantly renege by speaking a language that is not the common one will shortly find themselves being spoken to in an unpredictable language as well.

10.22

In addition to this explanation of altruism (which is strongly reminiscent of Axelrod's 1984 Tit-for-Tat approach), many theorists have suggested that altruism may evolve through some process of kin selection. In other words, an agent will tend to be ``nice'' to others -- even if there is potential harm to itself -- in proportion to the degree that those others are related. That way, even though it might die, its genetic material is more likely to survive than if it didn't. Oliphant applies this approach to explaining the emergence of communication systems, suggesting that it is in an individual's interests to communicate clearly with kin, and hence stable systems can evolve.

10.40

That said, the paradigm used by Werner and Dyer may be able to be elaborated to incorporate more complexity and require more of the agents in the scenario. For instance, the ``ears'' used by the males can be improved, allowing them to hear multiple females at once. This would require them to develop the ability to screen out which calls were most important (i.e. which females were closer). As more complexity is added to the scenario, more complex language-like behavior could potentially emerge.

10.50

When learning is enabled, fitness is dramatically increased. There are now 59.84 cooperations per breeding cycle, which is 857% above chance, increasing at 100 times the rate when communication was suppressed. We can see evidence of communicative activity when we examine the denotation matrix representing the collective communication acts of the entire population. By the end of the run, some symbols have come to denote a unique situation, and certain situations have symbols that typically denote them. The entropy of the denotation matrixes is much smaller when communication is enabled (H = 3.95) and when communication and learning are enabled (H = 3.47) than when neither is (H = 5.66 -- almost the maximum level of 6). In this way it is possible to tell that the strings emitted by the agents are in some way contentful.

10.52

Most interesting are the characteristics of the ``language'' that evolves. For the most part, there is an extensive reliance on the second (most recent) symbol of a pair -- not surprising, since that doesn't require the organism to remember the first. However, there are occasional forms where both symbols were used, though they are not prevalent. This seems to indicate that, while they aren't completely ineffective, the machines don't evolve to make full use of the communicative resources at their disposal by developing multiple-symbol ``syntax.'' MacLennan and Burghardt suggest that this indicates that this step is evolutionarily hard, especially since it doesn't seem to improve as the organisms are given more time to evolve -- rather, they plateau at a certain point and never improve after that. Nevertheless, even under circumstances where a multiple-symbol language would have resulted in improved communication, organisms were capable of developing something.

==============

BATALI, J. (1994) Innate Biases and Critical Periods: Combining Evolution and Learning in the Acquisition of Syntax. Artificial Life: Proceedings of the Fourth International Workshop on the Synthesis and Simulation of Living Organisms. eds. R. Brooks and P Maes. MIT Press: Cambridge, MA.

BATALI, J. (1995) Small signaling systems can evolve in the absence of benefit to the information sender. Draft.

BATALI, J. (1998) Computational simulations of the emergence of grammar. Approaches to the Evolution of Language: Social and Cognitive Bases. eds J. Hurford, M. Studdert-Kennedy, C. Knight. Cambridge University Press.

...

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CHOMSKY, N. (1981a) Government and Binding. Foris, Dordrecht

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STROMSWOLD, K. (1995) The cognitive and neural bases of language acquisition. The cognitive neurosciences, ed M. Gazzaniga.
Cambridge, MA: MIT Press.
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ugh how painful... worthless trudge through troughs of funky baloney, FAR afield from my anticipated snack or meal...