Biology Reference
In-Depth Information
the four years following the publication of his 1925
Nature
paper, pro-
viding more details about his discovery in that manuscript. Dart went
much further in this monograph than simply describing Taung's entire
sulcal pattern for the first time. He also bolstered his argument that
Taung's brain was advanced compared with those of apes by detailing
expansions that had occurred in three significant areas of the cerebral
cortex. Long before my two graduate students and I realized that endo-
casts of gracile australopithecines had more advanced shapes than those
of robust australopithecines, Dart had discovered that the overall shape
of the Taung endocast was advanced toward a human condition. It is a
shame that his manuscript was never published, because Dart's observa-
tions about brain shape could have sparked an earlier understanding of
certain important details about brain evolution.
brain shape
Dart devoted 33 pages of his 1929 manuscript to a discussion about the
shape of three cortical association areas on the Taung endocast. (Unlike
the primary sensory and motor areas, association areas process and syn-
thesize information that is received from various parts of the brain.) This
interesting aspects are discussed here, and because Dart's unpublished
manuscript is of historical importance, his own words are quoted at some
endocast in his 1925
Nature
paper, it was startling to learn that, by 1929,
Dart thought information about expansion in three cortical association
areas that were widely distributed across the endocast was the
only
type
of evidence that could indicate the evolutionary relationship between
Australopithecus
and humans:
It is important to reiterate that the only type of evidence the cast can yield,
which would indicate proximity to Man, is that of
expanded association cortices;
which by their localisation, have profoundly affected the shape of the brains
as compared with those of living Apes. Further, the particular regions of the
