Wednesday, October 18, 2006

Steps for the evolution and devlopment of languages

There is an interesting post at the Babel's Dawn, highlighting the work of David Rose in relation to SFL.

As per David, some pre-requisites are required for the evolution and development of languages as we know them.

Four conditions are suggested for developing explanatory models that may account for these linguistic phenomena. These include (a) a mechanism for reproducing complex cultural behaviors intergenerationally over extended time, (b) a sequence by which articulated wordings could evolve from nonlinguistic primate communication, (c) extension of the functions of wording from enacting interpersonal interactions to representing speakers’ experience, and (d) the emergence of complex patterns of discourse for delicately negotiating social relations, and for construing experience in genres such as narrative. These conditions are explored, and some possible steps in language evolution are suggested, that may be correlated with both linguistic research and archaeological models of cultural phases in human evolution.

Edmund Bolles summarizes this as below:

Rose’s four steps required for the growth and survival of language are:

  1. reproducibility: along with the “suite of biological adaptations” for speaking, there has to be some “mechanism” for precisely reproducing the language that happens to be spoken wherever one happens to be born. Many inquiries into language acquisition assumed this reproducibility is purely biological, but Roses insists that language is reproduced across generations “by cultural means.” In other words, children learn language from their elders. We will see on this blog that this explanation is not accepted quite as widely as a novice might think. One thing is clear, we got this skill after we said goodbye to the chimpanzee’s line of descent.
  2. exchangeability: Once speakers have the ability to reproduce words they can “exchange” them. Rose takes the idea of an exchange of words more literally than I do; thus he talks about “exchange behavior” in primates, but the basic idea of being able take and modify one another’s existing words to create new ones appears sound enough. The interesting thing about such interactions is that both parties in the exchange “get” it. The usage is understood as a bit of wit or cleverness rather than as an error, so wit too is something added to our species when we had parted from the surviving primates.
  3. extendibility: one very peculiar quality of humans is what a resourceful species we are, able to turn established tools to new tasks as the purpose demands. A digging tool becomes a backscratcher becomes a probe. Equally, we can extend the uses of our verbal tools. Thus, words which were surely first “exchanged” as tools for interpersonal actions could be extended for use in expressing ideas and then extended again to be used in thinking through some complex set of ideas. At this point biology is left in the dust as the role of language is extended at a pace that far outdistances plodding natural selection.
  4. combinability: the various extensions of speech can be combined to produce still more verbal wonders, such as stories and polite behavior that lets people negotiate delicate situations without giving offense. At this point we can speak of craft, maybe even artistry. Speech, thought, and culture has moved so far from its primate roots that the idea of common descent becomes surprising.
To me these bring to mind the more genetic and physical (as opposed to the cultural based that Rose presumes them to be) pre-requisites for language, in particular, and symbolic manipulation in general, that Premack had outlined recently. I had commented on the same earlier by integrating those with the existing stage-based developmental model of language evolution/development.

I'll briefly recap the pre-requisites that Premack had identified:

  • Voluntary Control of Motor Behavior. Premack argues that because both vocalization and facial expression are largely involuntary in the chimpanzee, they are incapable of developing a symbol system like speech or sign language.
  • Imitation. Because chimpanzees can only imitate an actor's actions on an object, but not the actions in the absence of the object that was acted upon, Premack suggests that language cannot evolve. .
  • Teaching. Premack claims that teaching behaviors are strictly human, defining teaching as "reverse imitation" - in which a model actor observes and corrects an imitator.
  • Theory of Mind. Chimps can ascribe goals to others' actions, but Premack suggests these attributions are limited in recursion (i.e., no "I think you thought he would have thought that.") Premack states that because recursion is a necessary component of human language, and because all other animals lack recursion, they cannot possibly evolve human language.
  • Grammar. Not only do chimps use nonrecursive grammars, they also use only words that are grounded in sensory experience - according to Premack, all attempts have failed to train chimps to use words with meanings grounded in metaphor rather than sensory experience.
  • Intelligence. Here Premack suggests that the uniquely human characteristics of language are supported by human intelligence. Our capacity to flexibly recombine pieces of sensory experience supports language, while the relative lack of such flexibility in other animals precludes them from using human-language like symbol systems.
To me, the Imitation and Teaching seem to be the cognitive mechanisms by which reproducibility of languages across cultures and generation is ensured.

Theory of mind abilities would definitely be utilized and instrumental in the process of excahngeability, whereby one can use tokens like words to exchange meanings. For this mechanism to evolve, an ability to understand that others have mental states that are similar to us is necessary and only then can one comprehend what that person means when he uses a particular token. Also, the mirror system , that might be involved in ToM module , may also be sufficient to explain the evolution of linguistic words from non-linguistic communication.

Grammatical abilities like recursion and ability to use metaphors can be directly mapped to the capabilities like combinability and extendability, whereby complex linguistic devices can be combined to produce complex discourses and novel metaphors used for extending the semantics associated with a word.

I'm quite intrigued and excited by such commonalities! Does this excite you too? Let me know via comments.

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