29 April - David Perlmutter UCSD Linguistics
How Many Times Did Language Originate?
    Are all the languages in use today descended from a single ancestral language that was once spoken by all humankind?  Or did language originate more than once in human history – perhaps many times?  The Single Origin Hypothesis and the Multiple Origins Hypothesis are competing hypotheses about the origin of language.
    These hypotheses are rooted in different conceptions of the human capacity for language.  In order for the Single Origin Hypothesis to be true, this capacity would have to consist of the ability to learn a language and pass it on to the next generation, but not the ability to create language anew.  In order for the Multiple Origins Hypothesis to be true, the human capacity for language would have to encompass both abilities.  If for any reason the chain of transmission of language were broken in a community, the human capacity for language would ensure the emergence of a new language.
    The two hypotheses’ predictions can be tested experimentally, at least in principle.  The Great Experiment that would be necessary would take a group of human beings without language and cut them off from any exposure to language.  Given the human need to communicate, some kind of communication system would develop, but what kind of communication system would it be?   Would it be a full human language, with all the essential properties of human languages?  Or would it be a very different kind of communication system?  The emergence of a full human language would support the Multiple Origins Hypothesis, for it would show that language had developed more than once:  once in the dim human past and once in the experimental group.  And if language develops under these conditions, it could have developed a number of times in human history.  On the other hand, the emergence of a communication system that is not a full human language would support the Single Origin Hypothesis.
    While ethical considerations rule out performing such an experiment on human beings, this talk argues that nature has already performed the Great Experiment for us, with deaf people as subjects.  Cut off by deafness from the language of the surrounding society, what kind of communication system have they developed?
    Two questions must be answered:
        (1)  Did sign language actually develop under the conditions of the Great Experiment?
        (2)  Is sign language language?
    This talk argues that both questions must be answered affirmatively, based on analysis of American Sign Language (ASL), the language of Deaf communities in the United States and most of Canada.  It is argued that ASL has the essential properties of human language and that it could not have originated in English or any other spoken language.  Relevant data come from:
        a)  the properties that make signs more like spoken words than like gestures
        b)  the ways signs express complex meanings
        c)  the syntactic structure of ASL sentences
    Affirmative answers to (1-2) mean that language originated at least twice in human history, supporting the Multiple Origins Hypothesis.  Additional evidence from other sign languages strongly suggests that language has originated many times.
    The results of the Great Experiment have important consequences for an understanding of the evolution of language.  It is common for theorists to concentrate on ways that speech could have evolved.  The results of the Great Experiment exhort us to concentrate instead on the evolution of the human capacity for language.  Once that capacity is in place, the emergence of language – whether in speech or in sign – takes care of itself.