22 April - Robert Kluender UCSD Linguistics

The Evolution of Grammatical Properties in the Absence of Symbolic Reference

    Most accounts of the evolution of language tend to focus on the problem of symbolic reference and how it emerged.  Even when the enterprise is successful, however, there is no easy way to get from symbolic reference to the emergence of grammar.  Accounts that focus more exclusively on the emergence of grammatical properties either tend to assume that these cannot have been adapted for, or when an adaptive mechanism is assumed, are at a loss to provide concrete evidence of intermediate evolutionary stages.
    In this talk, an attempt is made to circumvent these problems by tracking the evolution of a particular property of gesture, that of directional movement used to encode participants in an action.  Similarities in the form and function of directionality in both non-linguistic gesture and the grammaticized verbal agreement morphology of signed languages suggest that gestural directionality eventually became grammaticized in human signed languages.  This then provides us with a unique opportunity to trace the development of a linguistic property from its non-linguistic roots through its progressive elaboration in a variety of existing species and human populations, at various levels of cognitive development:  hearing adults under experimental conditions, pre-linguistic children acquiring language, and captive chimpanzees, bonobos, and gorillas that innovate their own gestural systems of communication.
    It turns out that not only is symbolic reference not necessary for the development of directionality into a grammatical property, it even seems to act as an impediment.  Thus the gesture of humans becomes demonstrably more language-like when the vocal channel (i.e. symbolic speech) is suppressed.  The purely iconic and indexical nature of gesture encourages a reliance on directionality to ensure effective social communication.  In captive apes, the use of communicative manual gesture seems to be tied to situations vital to survival needs and reproductive advantage:  food begging, socio-sexual positioning, and the social regulation of aggressive conflict situations.
    Historically, grammaticization of verbal agreement in spoken language involves incorporation of pronominal elements (indicating discourse referents) into the verbal morphology.  Could this process be mirroring a similar, earlier process that first took place in the manual modality?  This would make sense in so far as communicative manual gesture is volitional, and hence under cortical control, and precedes speech both phylogenetically and ontogenetically.  It thus seems that the foundations for grammatical inflection could have first been laid down in the manual modality, and then subsequently transported into the vocal medium once vocalization was tamed and took over primary communicative responsibility.