[Paleopsych] SW: On the Origins of Human Language

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Anthropology: On the Origins of Human Language
http://scienceweek.com/2004/sa041203-3.htm

    The following points are made by Gary F. Marcus (Nature 2004 431:745):
    1) If, as Francois Jacob argued, evolution is like a tinkerer who
    builds something new by using whatever is close at hand, then from
    what is the human capacity for language made? Most accounts of the
    evolution of language have focused on characterizing changes that are
    internal to the language system. Were the earliest forms of language
    spoken or (like sign language) gestured? Did language arise suddenly?
    Or did it emerge gradually, progressing step by step from a simple
    one-word "protolanguage" (limited to brief comments about the "here
    and now") into a more complex system that combined individual words
    into structured meaningful sentences encompassing the future, the past
    and the possible -- as well as the concrete present? Regardless of how
    these questions are resolved, if we seek the ultimate origins of
    language, we also need to look further back, beyond the first
    protolinguistic systems, to whatever prelinguistic systems may have
    preceded any form of language.
    2) Possible prelinguistic precursors might include systems for
    planning or sequencing complex events, categorization, automating
    repetitive actions, and representing space and time. In each case,
    there are parallels between candidate prelinguistic cognitive (or
    motor) precursors and systems found in language. For example, many
    animals are able to construct mental maps for navigation, and all
    known languages draw heavily on spatial metaphors. Thus, it is
    tempting to conclude that machinery for the mental representation of
    space plays some role in -- or is at the very least available to --
    the machinery for language.
    3) But parallels alone are not enough to establish shared lineage
    between two systems -- they could instead represent convergent
    (independent) evolution. For example, a language system could have
    evolved its own machinery for automating repeated tasks, independent
    of pre-existing machinery for automatizing other cognitive functions.
    A more telling way of establishing prelinguistic ancestry could come
    from evolutionary contrivances, properties of language that existed
    not because of some selective advantage, but simply because they have
    descended from ancestral systems evolved for other purposes. Just as
    the panda's thumb is not a true digit, but a modified sesamoid bone
    pressed into service for gripping bamboo, some properties of our
    capacity for language may be better understood not as optimal
    solutions to a system for communication, but as cobbled-together
    remnants of ancestral cognitive systems.
    4) In language, one good candidate comes from the study of memory.
    According to an optimal design, if the capacity for understanding
    language were evolved from scratch, it would be possible to reliably
    retrieve individual bits of syntactic structure on the basis of their
    location in a hierarchical structure, independently of their content
    -- as in most digital computers. Instead, human language systems seem
    to rely on "content-addressable" memory, a form of memory --
    widespread in the vertebrate world and with an apparently ancient
    evolutionary source -- that retrieves information directly on the
    basis of its content, rather than through location. Unlike a
    computer's binary-tree structure, content-dependent memory in
    mammalian brains is subject to degradation over time and to
    interference between similar or intervening items.
    5) Human speakers are thus less likely to resolve the relation between
    "admired" and "the newspaper" in a sentence such as: "It was the
    newspaper that was published by the undergraduates that the editor
    admired," than in the briefer sentence "It was the newspaper that the
    editor admired." In languages such as English that lack rich
    case-marking, in most cases listeners can correctly interpret only two
    levels of embedding, not because of a strict limit on the size of
    representable binary trees, but because similar items become confused
    in memory.(1-5)
    References (abridged):
    1. Christiansen, M. H. & Kirby, S. Language Evolution (Oxford
    University Press, 2003)
    2. Gould, S. J. The Panda's Thumb (Norton, 1980)
    3. Jackendoff, R. Foundations of Language: Brain, Meaning, Grammar,
    Evolution (Oxford University Press, 2002)
    4. Marcus, G. F. The Birth of the Mind (Basic Books, 2004)
    5. McElree, B. et al. J. Mem. Language 48, 67-91 (2003)
    Nature http://www.nature.com/nature
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    Related Material:
    LANGUAGE GRAMMAR PROPOSED TO HAVE EVOLVED BY NATURAL SELECTION
    Notes by ScienceWeek:
    Language is considered a quintessentially human trait, and attempts to
    shed light on the evolution of human language have come from diverse
    areas including studies of primate social behavior, the diversity of
    existing human languages, the development of language in children, the
    genetic and anatomical correlates of language competence, and
    theoretical studies of cultural evolution, learning, and lexicon
    formation. One major question is whether human language is a product
    of evolution or a side-effect of a large and complex brain evolved for
    non-linguistic purposes.
    The following points are made by M.A. Nowak and D.C. Krakauer (Proc.
    Nat. Acad. Sci. 1999 96:8028):
    1) The authors provide an approach to language evolution based on
    evolutionary game theory, the authors exploring the ways in which
    protolanguage can evolve in a nonlinguistic society and how specific
    signals can become associated with specific objects.
    2) The authors argue that grammar originated as a simplified rule
    system that evolved by natural selection to reduce mistakes in
    communication, and they suggest their theory provides a systematic
    approach for thinking about the origin and evolution of human
    language.
    Proc. Nat. Acad. Sci. http://www.pnas.org
    --------------------------------
    Related Material:
    ON THE GESTURAL ORIGINS OF HUMAN LANGUAGE
    Notes by ScienceWeek:
    A view currently held by many anthropologists and linguistics
    researchers is that the remarkable flexibility of human language is
    achieved at least in part through the human invention of grammar, a
    recursive set of rules that allows the generation of sentences of any
    desired complexity. The linguist Noam Chomsky has attributed this to a
    unique human endowment termed "universal grammar", with Chomsky
    suggesting that all human languages are variants of this fundamental
    endowment.
    The following points are made by Michael C. Corballis (American
    Scientist Mar-Apr 1999 87:138):
    1) There is little doubt that the great apes (orangutan, gorilla,
    chimpanzee) (and perhaps other species such as dolphins) can use
    symbols to represent actions and objects in the real world, but these
    animals lack nearly all the other ingredients of true language.
    2) Since the common ancestor of human beings and chimpanzees lived
    approximately 5 million years ago, it is a reasonable inference that
    grammatical language must have evolved in the hominid line (i.e., the
    line of human primates) at some point following the split from the
    line that led to the modern chimpanzee. There has been much
    disagreement as to when this might have happened.
    3) One major view holds that it is impossible to conceive of grammar
    as having been formed incrementally; grammar therefore must have
    evolved as a single catastrophic event, probably late in hominid
    evolution. But many researchers hold a contrary view, that language
    evolved gradually, shaped by natural selection, and that the cognitive
    prerequisites of language are already present in the great apes and
    antedated the split of our hominid ancestors from the chimpanzee line,
    probably by several million years.
    4) The author suggests that at least a partial reconciliation of these
    alternative perspectives may be that language emerged not from
    vocalization, but from manual gestures, and switched to a vocal mode
    relatively recently in hominid evolution, perhaps with the emergence
    of Homo sapiens. This is an old idea, apparently first suggested by
    Condillac in the 17th century, but argument in its favor has continued
    to grow.
    5) The author points out that there are countless different sign
    languages invented by deaf people all over the world, and there is
    little doubt that these are genuine languages with fully developed
    grammars. The spontaneous emergence of sign languages among deaf
    communities everywhere confirms that gestural communication is as
    natural to the human condition as is spoken language. Indeed, children
    exposed from an early age only to sign language go through the same
    basic stages of acquisition as children learning to speak, including a
    stage when they "babble" silently in sign.
    6) The authors proposes the following speculative scenario concerning
    the historical development of human language:
    a) 6 or 7 million years ago: Simple gestures first anticipated more
    complex forms of communication, shortly after the human line diverged
    from the great apes. At this stage vocalizations served only as
    emotional cries and alarm calls.
    b) Approximately 5 million years ago: With the advent of bipedalism, a
    more sophisticated form of gesturing involving hand signals may have
    evolved among the early hominids now labelled as "Australopithecus".
    c) Approximately 2 million years ago: In association with the
    increasing brain size of the genus Homo, hand gestures became fully
    syntactic (i.e., with syntax; with ordered arrangements), but
    vocalizations also became prominent.
    d) 100,000 years ago: Homo sapiens switched to speech as its primary
    means of communication, with gestures now playing a secondary role.
    e) Modern times: The development of telecommunication now permits the
    routine use of spoken language in the complete absence of hand
    gestures, but even so, many people find themselves gesturing when they
    speak on the telephone.
    7) Concerning the question of what it was that enabled our species to
    prevail over other large-brained hominids, the author concludes:
    "Perhaps the most plausible answer is that they prevailed because of
    superior technology. But that technology might have resulted, not from
    an increase in brain size or intelligence, but from a switch from
    manual to vocal language that allowed them to use their hands for the
    manufacture of tools and weapons and their voices for instruction."
    American Scientist http://www.americanscientist.org