Biology Reference
In-Depth Information
lateral brain surface which are especially expanded in Man and have affected
its general contour as compared with Apes, are three in number. They are
what Elliot Smith . . . has called the “three significant cortical areas” . . . and
are the parietal, the inferior frontal or prefrontal and the inferior temporal.
Genuine expansion in these regions . . . constitutes trustworthy evidence in
Although Dart had discussed the first cortical area, the parietal
association cortex, to a limited extent in 1925, in 1929 he noted that the
lunate and superior temporal sulci did not limit the area in which pari-
etal expansion had occurred but instead served merely as a guide to
“expansile changes” that had taken place in a large part of the back
Taung endocast that were correlated with this expansion, including an
increased arc and humanlike doming of the parietal cortex and also a
posterior protrusion of the occipital lobe that overhung the cerebellum
difference may be seen by comparing the back end of the Taung endo-
cast with that of the chimpanzee brain in figure 5.)
The second expanded area that Dart discussed for the Taung endo-
cast was at the other end of the brain, in the frontal lobe. He credited
this observation to his mentor, Elliot Smith, who observed that the edge
of Taung's frontal lobe was more pronounced over the eye sockets com-
pared with the shape seen in ape brains and that, in this regard, Taung
appeared to be as developed as
Pithecanthropus
(now
Homo
)
erectus
. Dart
attributed this bulging of Taung's prefrontal cortex to expansive shape
changes that had taken place at the edge of and underneath the frontal
He also noted that this “localized growth . . . bespeaks an advancement
in intelligence—of forethought and skill—such as is encountered in
no other Ape whatever, but which is found elsewhere only in Primitive
Man.”
36
The third area of Taung's endocast that Dart described as having an
advanced shape toward a human condition is near the middle and bot-
