Over the years, many efforts have been made to demonstrate that the human brain is appreciably different in structure from the brains of lower-order primates. In point of fact, such differences in gross anatomy are disconcertingly difficult to discern. The following are the average areas of the striate cortex (x) and the prestriate cortex (y) found for humans and for three species of chimpanzees (129).

Plot the data and superimpose the least squares curve, y = axb.

Area Striate Cortex, Prestriate Cortex x (mm2) 2613 1876 933 y (mm2) 7838 2864 1334 Primate Homo Pongo Cercopithecus Galago 78.9 40.8