Evolving mixed-media messages and grammatical language
secondary uses of the neural sequencing machinery needed for ballistic movements
pp. 163-179
in: Jan Wind, Brunetto Chiarelli, Bernard Bichakjian, Alberto Nocentini, Abraham Jonker (eds), Language origin, Berlin, Springer, 1992Abstract
A possible preadaptation for the neural machinery underlying language and thought can be seen in the neural circuitry required for planning sequential hand-arm movements such as hammering and throwing. If it isn't a standardized movement sequence such as the basketball free-throw, the thrower has to plan: to generate a family of variations on an approximate string of commands, and then judge each of those candidate strings against memories of what strings succeeded in the past for similar-but-not-identical conditions. Thus one needs an array of planning tracks rather like a railroad marshalling yard, with a "good-enough" train only occasionally let loose on the main track to overt action. Since hand-arm sequencing circuitry in the brain has a strong spatial overlap with where language circuitry is located in left brain, perhaps the same massively-serial architecture can do double-duty for language and planning ahead. The well-formed sentence and the reliable plan of action have some strong analogies to more familiar darwinian successes. But the transition during hominid evolution to humanlike language would seem to have faced some transitional tasks, and I suggest that a mixed economy of gestures, depictions, and vocalizations might have eventually led to a subject-predicate message format — and that syntax may have been introduced to deal with subject-object ambiguity when two nouns were present in a sentence.