Paraules clau:cognits, syntax of action, hierarchy in cortex, hierarchy in language, perception-action cycle, cross-temporal contingencies, prefrontal cortex.
Late in evolution, one particular brain structure and one particular cognitive function undergo enormous development: the first is the prefrontal cortex and the second is language. As this article argues, the two are intimately related. In the human, the prefrontal cortex reaches the size of almost one-third of the entire cortex; especially striking is the exponential evolutionary growth of prefrontal fibers and connections, well beyond the growth they reach in the large apes. At the same time, precisely because of that extraordinary growth in cortical connectivity, the primitive communication ability of the ape becomes language in the human. Thus, the question of the evolutionary continuity or discontinuity of either prefrontal function or language becomes moot. There is indeed a quantitative progression from animal to man in the development of the function of the prefrontal cortex and in the ability to communicate cognition and emotion; but the progression is so large and “sudden”, and exponentially so steep, that for all practical purposes both are step functions, qualitatively new and uniquely human.