Biology Reference
In-Depth Information
Taung's endocast would be sufficient to convince Grafton Elliot Smith
of the legitimacy of his claims and that others would then follow suit.
After all, Dart had learned to identify and interpret the grooves, bumps,
and convolutions on endocasts of various animals, including primates,
by studying for four years under Elliot Smith, the world's foremost
authority on the subject. Indeed, when Dart interpreted Taung's endo-
cast, he strongly invoked his mentor's own theory about human brain
evolution. But if Dart believed that would save Taung (and himself)
from a whirlwind of controversy, he was mistaken.
dart's interpretation of the endocast
Workmen who were quarrying for lime blasted Taung out of limestone
cliffs that contained passages and caves. Because of South Africa's propi-
tious geological conditions, Taung's endocast formed naturally, which
the child died its skull rested on its right side, and once the soft tissues
had disappeared, the cranial cavity partly filled with sand mostly on the
right. Later, the sand became packed and fossilized as it was covered by
percolating lime that formed a crystalline deposit on the inner surface
details of the right half of the cerebral cortex (outermost layer of the
brain that is responsible for conscious thinking and movements) and
the underlying cerebellum (which is important for coordinating move-
ments), which had been imprinted on the walls of the braincase when
Taung was alive. The endocast looked very much like the right half of
an actual brain, and, from it, Dart inferred that the volume of Taung's
braincase, or cranial capacity (a proxy for brain size), was 520 cm
3
, which
of cerebral cortex compared with the cerebellum was greater than an
The surface of an ape's brain typically has a large groove, or sulcus,
that borders the front end of the visual area, which was traditionally