A Comparative Approach to Study the Evolution of Human Brain Speech/Language Areas in Old World Monkeys and Great Apes

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The objective of this project is to meld the intellectual and methodological approaches contained within neurobiology and anthropology and arrive at a new way of looking at an old problem, the origin of human speech/language and its neural substrate, during primate and early human evolution. The working hypothesis is that the evolutionary substrate for brain mechanisms which underlie the unique human form of vocal-auditory communication was already present in our common ancestor with Old World monkeys if not much earlier. Further, that this basal neural substructure was incorporated and further elaborated, when early human ancestors changed from the long-standing primate pattern of territorial containment to become wide ranging bipeds in a highly demanding, cognitive and communicative novel environment. This project will use two modern neurobiologic techniques, 1) Magnetic Resonance Imaging with 3-D, quantitative, computerized image analysis, to address outstanding issues of gross anatomic interhemispheric asymmetries in regions of great ape and monkey cerebral cortex that are homologous to human brain language areas; and 2) Quantitative Immunocytochemistry to determine, in macaques, whether there is an asymmetric distribution of various brain chemicals in these brain regions that would lend support to the hypothesis of already well established hemispheric functional specialization.