We applaud the spirit of MacNeilage's attempts to better
explain the evolution and cortical control of speech by drawing on the
vast literature in nonhuman primate neurobiology. However, he
oversimplifies motor cortical fields and their known individual
functions to such an extent that he undermines the value of his
effort. In particular, MacNeilage has lumped together the functional
characteristics across multiple mesial and lateral motor cortex
fields, inadvertantly creating two hypothetical centers that simply
may not exist.