language

Seed is running a little article on the evolution of language, by lingust Juan Uriagereka:

A quasi-paradox has persisted within the field of linguistics, because the sudden emergence of such a complex, limitless system in a single species is hard to rationalize in terms of standard evolution. Its rapid spread makes language seem more like a viral epidemic that swept through the human population rather than a trait inherited through the typical dynamics of evolution.

Luckily, two recent advances have made it possible to rigorously address the problem of language's evolution for the first time. Molecular biology (including the publication of the human genome) and the so-called evo-devo paradigm now permit us to establish new and often quite unexpected connections among very different species. In addition, linguists' understanding of syntax -- how words are strung together into grammatical sentences—has developed to the point where language can be broken down into its basic procedural components. These components can now be seen to resemble traits observed in other species -- with functions that appear to be completely unrelated to familiar thought processes. Language may indeed be unique to humans, but the processes that underlie it are not.

It hits on many of the big topics, including the comparative biology of communication in finches, the regulatory role of FoxP2 in birdsong, and the brain processes underlying syntax.

I will differ from Uriagereka on this point:

The publication of the Neanderthal genome should tell us just how different their FoxP2 gene really is from our own.

Human FoxP2 differs from chimpanzees by two derived amino acid substitutions. If Neandertals were different from us (which seems likely, given the recent evidence of selection on the gene), then they would have had only one of these substitutions. It's an answer we don't actually need the Neandertal genome for. Now, if only we could start thinking about some other language-related genes.

The PNAS early edition is like a one-stop shop today. Here's a paper where the authors set up an experimental model for language origins:

The emergence of simple languages in an experimental coordination game

Reinhard Selten and Massimo Warglien

We investigate in a series of laboratory experiments how costs and benefits of linguistic communication affect the emergence of simple languages in a coordination task when no common language is available in the beginning. The experiment involved pairwise computerized communication between 152 subjects involved in at least 60 rounds. The subjects had to develop a common code referring to items in varying lists of geometrical figures distinguished by up to three features. A code had to be made of a limited repertoire of letters. Using letters had a cost. We are interested in the question of whether a common code is developed, and what enhances its emergence. Furthermore, we explore the emergence of compositional, protogrammatical structure in such codes. We compare environments that differ in terms of available linguistic resources (number of letters available) and in terms of stability of the task environment (variability in the set of figures). Our experiments show that a too small repertoire of letters causes coordination failures. Cost efficiency and role asymmetry are important factors enhancing communicative success. In stable environments, grammars do not seem to matter much, and instead efficient arbitrary codes often do better. However, in an environment with novelty, compositional grammars offer considerable coordination advantages and therefore are more likely to arise.

The subjects were given a small set of letters to work with, and a relatively large set of graphical symbols (I'll call them icons) to encode with the letters. The icons are illustrated in the paper; they sort of look like Kanzi-like ideograms. The players had to combine letters to attempt to communicate icons as they appeared on a screen, sending the letters across an anonymous channel with another player. Each player's correspondence of icons and letter-combinations amounts to a code. For this system to work as a communication between the two subjects, they had to arrive at some conventions, so that they would share the same code. The form and effectiveness of the conventions is what the researchers were trying to study.

Out of that abstract, this sentence strikes me as interesting: "Our experiments show that a too small repertoire of letters causes coordination failures."

Why should that be? In the experiment, the use of letters carried a cost to the sender -- like sending a telegram, charged by the letter. So short messages carry a higher payoff. But when there are very few letters to choose from, it is impossible to form many unique messages, unless the messages combine a lot of letters. So players supplied with a "small repertoire" of letters should try to economize communications by packing as many different combinations into as few letters as possible. And that leads to confusion, since messages will be minimally redundant and hard to remember. Give them more letters, and they can make many more combinations with shorter message lengths. Problem solved.

This is essentially an information theoretic explanation for why a large phoneme count is advantageous for human language, which the authors point out:

From a logical point of view, two symbols are sufficient for the construction of a code. In principle, communication could be based on a binary code. However, it seems to be the case that the availability of a sufficiently large variety of letters not only makes it easier to achieve communication efficiency but also has a cognitive effect that facilitates linguistic coordination (Selten and Warlien 2007:7363).

That's not a new insight, but it is interesting that, in these experiments, the value of a relatively large letter diversity is derived from the explicit per-letter cost of transmission together with an apparently greater comprehensibility of messages in systems that employed greater letter diversity. Both the learnability and transmission cost factors work in the same direction in the context of this experiment.

One essential ingredient to a successful game was, in a sense, hidden: two players trying to develop a common code could achieve a higher payoff in the long run if they very quickly differentiated their roles into a single "teacher" and a single "learner." In the context of the game, if both players tried to adjust to each others' codes, they would end up changing past each other, and mismatches still persisted. But if one player consistently changed and the other remained constant, every change tended to increase payoff by increasing the consistency between the two players' use of codes.

Last, the icons themselves were chosen by the experimenters to exhibit some similarities in form that might have been exploited by the players in forming their codes. For example, the symbol set included open circles and triangles, circles and triangles with dots in them, circles and triangles with plus signs in them, etc.

Some players ended up forming codes that randomly assigned sequences (generally pairs) of letters to these icons, irrespective of their shape. Every icon gets essentially a random one or two letters.

Some players arrived at codes in which all circles were encoded by a letter combination beginning with, say, "R", and all triangles by a combination beginning with, say, "S". The researchers considered these codes to be "grammatical", because the letter combinations had a clear syntactic structure with one position assigned to indicate the shape of the icon, and later positions other information.

Some players formed codes that were grammatical, assigning a position to the shape of the icon, and also assigned the same letter for any shape having the same inner sign. So every icon containing a plus sign might have a "M" as the second letter, and every one containing a dot might have a "Z" as the second letter. The researchers considered these grammars to be "compositional", because the two positions each encoded separate information, which when brought together communicated combined information in a consistent way across all icons.

In the context of the experiment, using a grammatical form for the code was somewhat costly, since it predicated that a certain number of letters be used for each figure regardless of the actual frequency with which they were presented.

By the most complicated phase of the experiment, which involved thirty-six different icons to encode with 10 letters, almost everybody who came up with a grammatical code also made it compositional. It just seems like if people were going to systematize their code by shape, they did it, well, systematically -- using different letters to encode different kinds of information about the icons independently. Since the players built up to this phase of the experiment with simpler systems of icons, the experimenters could observe what happened as things got more complicated. At the earlier stages, there were a number of different noncompositional grammars used, and all of them were chucked when things got complicated.

But still, in a majority of cases, the pairs of players still didn't arrive at a single code by the end of the trials. The researchers were interested that compositional grammars were successful in this phase of the experiment, which they interpreted as involving "novelty" since each icon was presented only once. Clearly there was a premium on a system that could get things right that hadn't been practiced, and only the "compositional" alternative really allowed that to happen in this context. The authors conclude:

(iii) In stable environments as those considered in point ii, grammar does not matter much, and efficient arbitrary codes often do better. However, compositional grammars have the advantage of being more easily extendable to broader environmental demands. Noncompositional grammars are more fragile and are easily lost if new conditions have to be met.

(iv) In an environment with novelty, in the sense that often the need arises to express something that never has been expressed before, compositional grammars offer considerable coordination advantages. Therefore, under such circumstances, compositional grammars are more likely to arise. In this respect, our findings parallel and complement hypotheses proposed in the literature on language evolution (28, 29). In our experiments, all subjects have grammatical competence but they make relatively little use of it unless pressure of novelty gives them an incentive to do so (Selten and Warglien 2007:7365).

Well, this experiment isn't enough to demonstrate all that, but the cost and incentive structure makes it an interesting addition to theoretical arguments favoring these points.

References:

Selten R, Warglien M. 2007. The emergence of simple languages in an experimental coordination game. Proc Nat Acad Sci USA 104:7361-7366. doi:10.1073/pnas.0702077104

OK, maybe not mixmasters, exactly, but Mixing Memory does review this paper on marmoset reactions to human music by McDermott and Hauser, so I don't have to!

It's a good follow-up to my post from earlier this week, if you're interested in current research on the neuroscience and evolution of music abilities in humans.

Here's a quote from the conclusion of the paper to give an impression of why it is interesting.

However, despite the apparently aversive response monkeys have to many musical stimuli, we found for the first time evidence that they do have nontrivial preferences for some musical stimuli over others, and our results suggest that tempo is a critical variable.

Is the monkey response to tempo homologous to the human response to tempo? Further work is needed on this topic, but our results at least leave this possibility open. Humans obviously do not always prefer slow tempos to fast, but differences in temperament could cause tamarins and marmosets to find arousing stimuli aversive, whereas to humans they would merely be stimulating. Many stressful events in the natural environment, such as fights and storms, feature rapid sequences of acoustic events, and it is thus conceivable that animals have come to associate such stimuli with high levels of arousal. Future work using direct measures of arousal could provide further support for this hypothesis. It is also interesting to note that the alarm calls of tamarins and marmosets consist of short broadband bursts repeated at very high rates (Fig. 7 shows one such call from a tamarin). This acoustic structure is common to certain types of alarm calls in species ranging from monkeys and squirrels to birds (Marler, 1955), and could be related to the response nonhuman animals have to fast-tempo stimuli. Taken as a whole, however, the body of work on music perception in nonhuman primates suggests fundamental differences in the way they respond to musical stimuli compared to humans (McDermott and Hauser 2006:9-10).

That doesn't say too much about the necessary cognitive and perceptual processes that go into this kind of reaction -- whether aversive or not -- but it does suggest some relevant environmental noise analogues that might influence or constrain the reactions. One wonders whether playing their own chirps at a much higher tempo (part of the experiment) would be perceived in a threatening manner because of the combination of alienness and familiarity. Appropriate vocalizations themselves might change over time in natural groups, but they would in all cases be under selection to maintain appropriateness in constrast with their surroundings. So startlingly inappropriate vocalizations might be scary, even if their components were familiar -- sort of like seeing somebody on the street corner chanting gibberish.

So maybe studying these reactions in monkeys is question-begging. The real question is what about the human mind makes music compelling or attractive for people? We can say that whatever that is, these primates either don't have it or differ from humans sufficiently to make them not react the same way as humans to human music. But then, humans react quite differently to different brands of human music, in a way that is clearly culturally influenced if not completely culturally determined (and the balance between these alternatives is indeterminate).

Maybe it would be helpful to know if different populations of primates exhibit reactions that are comparably different to the differences in reactions to music among humans. We may not share the same affinities, but maybe we share similar dimensions of variability.

References:

McDermott J, Hauser MD. 2006 Nonhuman primates prefer slow tempos but dislike music overall. Cognition (in press) Preprint

Just taking some notes on a paper from last year by Helga Andresen, on the ways that role playing by preschool-age children can illuminate language and metacommunication development. I recognized a lot of my own children in the descriptions and examples.

Bateson (1955) postulates the existence of metalinguistic rules which determine how linguistic signs are related to non-linguistic entities like objects, persons, actions and places. These rules themselves, of course, cannot be linguistic in nature.

Bruner [1983] analyzed the development of mother-child interaction within the formats over many months and showed that the child constructs knowledge and anticipation of the interaction sequences and thus successively internalizes the structure of the format. This happens during the second half of the first year. First, the child adjusts his own vocalizations, miming and gestures to this structure until, more and more, he takes over the active part of the ongoing communication. Ritualization and repetition of the interaction make it possible for the child to recognize its structure. Above all, it is the close and fixed relations between verbal utterances and the non-verbal context that give children the chance to realize that the vocal activity of the mother refers to something beyond it and to realize the meanings of the utterances. Therefore the formats may be taken as an instantiation of those metalinguistic, non-verbal rules postulated by Bateson.

These considerations explain why early language use must be sympraxic; otherwise, children would have no chance to grasp the symbolic function of language (Andresen 2005:394).

Andresen has some fascinating examples where she documents interactions between children during roleplay, showing how much of the communication occurs within the roles and how much is metacommunication about the nature of the roleplay (a surprisingly large proportion).

The finding that older children produce less explicit metacommunication is of special interest. At first glance it may be surprising because from a scientific view it would be suggestive to propose that explicit metacommunication demands complex cognitive and communicative abilities which can be developed only on the basis of complex communicative skills which are beyond the scope of 4-year-old children. But metacommunication does not vanish out of play when children grow older; on the contrary, the pretend play of older children is much more complex than in the earlier years and contains a lot of transformations. Qualitative analyses of the older children's play in the Flensburg corpus show that they produce more implicit metacommunication than the younger ones. So, during the preschool period metacommunication changes from explicit to implicit performance (Andresen 2005:401-402).

A passage follows that discusses the complexity of carrying off implicit metacommunication -- which we may take as deliberately structuring communication in a form that itself more or less unambiguously conveys its context. In other words, implicit metacommunciation takes advantage of certain redundancies available in communication -- such as special same-meaning grammatical structures, gestures, tones, etc. -- to context-mark the communication.

Andresen then connects the progression from explicit to implicit in terms of Vygotsky's model of cognitive development:

According to [Vygotsky], internal mental processes arise out of external, interactive and communicative processes in earlier stages. He formulated this phenomenon as the transition from interpsychic to intrapsychic processes and functions during development (Andresen 2005:402).

And the subsequent section considers the development of egocentric speech along a similar timeline. Egocentric speech is inward-directed and regulatory in nature (with respect to actions); Andresen suggests a similar regulatory role for metacommunication. One might mention that egocentric speech has its own metacommunicative elements -- it being hard to mistake someone talking to herself for someone deliberately trying to communicate to others. In any event, this provides an opportunity to argue against simple word-object associations and in favor of the idea that roleplay indicates the ability to create linguistic (i.e., not here-and-now present) objects:

But an analysis of children's role plays clearly shows that already 4- year-olds are indeed able to create objects and meanings by linguistic means: for example, Aunt Maria, in the play of Hilde and Ingrid, who comes into existence through Hilde's utterance on the metacommunicative level and whose existence afterwards can be presupposed within the play. If the children could not create new meanings and communicate them to each other, role play could not take place at all (Andresen 2005:404).

There is a lot of detail in this article, related to the interchange of parent and child joint attention, the development of metacommunication skills in parent-child interactions, and the emergence of role playing as a way for children to take on adult roles they are normally not permitted. It relates well to Tomasello's work and Gregory Bateson's as well as Vygotsky, who is the model for much of the theory.

References:

Andresen H. 2005. Role play and language development in the preschool years. Culture and Psychology 11:387-414. DOI link