The purpose of this research is to infer when in the process of human evolution septum deviation occurred, taking notice of the fact that a high incidence of the septum deviation is found in man, while a septum of anthropoid ape is vertical.
It is said that the ancestor of hominoid had evolved into the Modern man, from a kind of primates like an ape through the processes of the Australopithecus, the Pithecanthropus, the Neanderthal man and the Modern man respectively.
At which stage of the frocess of human evolution did the formation of the septum deviation occur?
We cannot learn at all any configuration of the nasal chambers of the fossil hominoids between the Australopithecus and the Neanderthal man through their skulls. Consequently in order to find out their configurations, therefore, I studied inductively the following three aspects:
I) The comparative anatomical study on a septum
II) Study on the septum deviation in man in various respects
III) Study on the morphological relationship and transition of the fossil hominoid skulls, especially in the brain skulls and the face skulls, referring to the documents.
The purport of the above third (III) study with the documents on the skulls of the fossil hominoid is as follows;
1) From the Australopithecus to the Neanderthal man, their brain cases are long mainly anteriorly and posteriorly ; so the brain skull of the Neanderthal man is markedly dolichocephalic.
2) The brain volume of the Neanderthal man is as large as the present man's or larger. But the maxillo-facial skull of the Neanderthal man is more primitive than the Present man's and similar to the Pithecanthropus'.
3) The remarkable transition in the evolutional process of the Neanderthal man to the Modern man are the brachy-cephalizafion of the brain skull, the formation of the forehead and the progressive reduction of the brow ridges and the maxilla (prognathion)
4) Therefore, it can be thought that, in form of the brain skull of the Neanderthal man to the Modern man, different kinds of transitions than ever before had occurred, and furthermore ; that at the Neanderthal stage the brain skull had started to involve an active effect on the maxillo-facial skull.
Eventually, I concluded from the above three studies that the formation of the septum deviation in man occurred at the Neanderthal stage.
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