Earthian is a misnomer, as it almost always refers to a single species among the vast array of forms that the small rotator cultivated. The species was, population-wise, a minority throughout the Faith Millenia; it was exceded in number by many of the nucleated forms. Despite this weakness—for power depended literally on size or quantity—it achieved to maintain control over all other forms.
The H. Sapiens had two assets that were unparalleled by any living or nonliving form. One was efficient symbolic communication; this species saved huge amounts of energy by communicating via a negligibly small percentage of its total body mass. The other was ultra high speed of parallel processing, maintained in an average culture for about 80 % of the organism’s life span.
Our information about the H. Sapiens brain is unfortunately limited to the work of this very organ, which/who conducted extesive research and produced volumes of narrative on the body that it resided in—or governed, or belonged to; the expression varied depending on the era, and there probably existed considerable within-group variation.
Note the densities in the magnified snapshot of the Training Nodes in the figure below. Those were located below the paws or claws—areas of intense training by way of whisper chains, usually initiated and controlled by a central brain. Whisper cascades are not visible at this magnification.