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Siegfried
Wednesday, June 30th, 2004, 12:52 PM
I found this image in my 'Race Research' directory, but cannot remember how I obtained with. Is it from Baker's book Race? And is it valid?

http://www.forums.skadi.net/attachment.php?attachmentid=15105

Frans_Jozef
Wednesday, June 30th, 2004, 01:18 PM
Yes, Part Three: Studies of Selected Human Groups, chapter 16: The Australids(Australian aborigines), p.293. :)

Explanation follows later, Siegfried, it's a complex reading and neurobiology isn't my terrain of "expertise"...

Frans_Jozef
Wednesday, June 30th, 2004, 01:29 PM
"Very interesting pecularities have been described in the occipital lobes of the cerebral hemispheres of Australids,(...).
In some of the Cebidae, and apparently in all the Cercopithecidae and Pongidae, there is a very evident crescentic furrow, the sulcus lunatus, isible in the occipital lobe of the cerebral hemisphere(Fig. 49A). This is produced by the extension of the visible area, on each side of the calcarine sulcus, round the posterior end of the hemisphere from the mesial to the lateral side of the brain, and then forward in such a way as to push the visual area over and beyond the position of the original sulcus and thus convert it into a sulcusoperculatus.
This overgrowth, which has been compared to part of the rim of a mushroom, leaves a deep , crescentic furrow between itself and the more anterior part of the occipital lobe.
Since this was thought to be one of the striking features that distinguished the brains of apes and monkeys from that of man, it was called, the Affenspalte (monkey cleft)."

Siegfried
Wednesday, June 30th, 2004, 01:39 PM
Thanks a lot, Frans; you've been helpful, as always. :)

Frans_Jozef
Wednesday, June 30th, 2004, 01:40 PM
" Gustav Retzius(...) claimed that an 'analogy' to the Affenspaltecould be found in the brains of certain Europeans, and Elliot Smith claimed that seven of Retzius'drawings support the latter's contention; but examination of the particular figure specified by Smith does not conform this(...).
The lunate sulcus does indeed occur in the brains of Europeans, buts as Sir Arthur Keith remarks, when it is recognizeable at all it is always placed considerable further back than in the apes; (...), the visual area does not extend nearly so far round the posterior end of the occipital lobe on to its lateral surface.
(...)
The external characters of the human cerebral hemispheres are somewhat variable from one individual to another, but in an attempt to provide a drawing of a typical arrangement of the sulci in the brain of an European in lateral view, it would be appropiate to omit the lunate sulcus, or to include a small one situated far back, as in Fig. 49C."