Sulcal Skirmishes - The Fossil Chronicles - page 66

little dimple labeled “L?” in figure 7 represent the top end of a lunate
sulcus? Sure. And if it did not, there is still plenty of room behind it to
accommodate an apelike lunate sulcus that simply didn't leave its mark
within Taung's braincase . 25
One other sulcus is equally telling when it comes to distinguishing
human from ape brains, namely the fronto-orbital sulcus (fo). In apes, this
short sulcus incises the edge of the frontal lobe and continues underneath
it. The fronto-orbital sulcus never appears on the surface of the frontal
lobes in humans, however, because it was displaced to deeper parts of the
brain during the evolutionary expansion of the cerebral cortex (figure 7) . 26
It is significant that Dart and I both identified the same sulcus as fo on
Taung's endocast. In his words, “There is the customary sulcus fronto-
orbitalis, incising the superciliary border of the cast, 20 mm. in front of the
Sylvian depression. ” 27 (Dart seemed to have been unaware that fo does not
appear on the surface of human brains when he clearly identified this fea-
ture on Taung and, further, argued that its configuration was humanlike.)
Taung's entire sulcal pattern was apelike, and Dart perceived most
of it accurately, although he was mistaken on a few identifications at
the back end of the endocast. 28 His critics knew this and were tough on
him, which upset him terribly. For example, he expressed the following
sentiments about the 1936 paper by Le Gros Clark and his colleagues
that debunked his identification of Taung's lunate sulcus: “In this inno-
cent looking paper these three British anatomists were striving to fol-
low up Sir Arthur Keith's (1931) thesis of discrediting the neurological
basis upon which my interpretation of the significance of the Taungs
discover[y] had originally rested. Their reputation locally in England
was such that, had no further australopithecine remains been coming to
light simultaneously, their views might well have prevailed.” 29
As we saw in chapter 3, Dart's reactions to the controversy surround-
ing his discovery were varied: He quit doing paleoanthropology for
some time, became depressed, threw himself into teaching and admin-
istrative work, and even had a nervous breakdown. His most construc-
tive response, however, was to write his extensive manuscript during