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The lengthening of the anterior portion of the cranial base in the white races. Craniometric studies no

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398
JOHN CAMERON
REFERENCES
1. Cameron, John. The Correlation between the Nasion-Basion Length and the
Maximum Glabella-Occipital Length. A m . J. Phys. Anthrop., 1925, VIII,
No. 2.
2. Cameron, John. The Cranio-Facial Axis of Huxley, Pt. 11. Comparative Anatomy. Tr. Roy. Soc. Canada, Third Ser., 1925, XIX.
3. Schultz, Adolph H. Anthropologische Untersuchungen an der Schiidelbasis,
Ziuich, 1917.
4. Todd, T. Wingate. Mathematical Calculation of Cranial Capacity, Am. J.
Phys. Anthrop., 1923, VI, No. 2.
THE LENGTHENING OF THE ANTERIOR PORTION O F T H E
CRANIAL BASE IN THE WHITE RACES
CRANIOMETRIC
STTJDIES,
No. 4
I n the second craniometric study attention was directed to the fact that
there was a shortening of the nasion-basion length in the American
White skull as compared to that of the American Negro. The difference
proved to be very slight, amounting t o 0.5 mm. in the male series, and
1.1rnm. in the female series, but its very definite character, and the fact
that it was consistent for the two sexes justified a full investigation int,n
the condition.
This discovery stimulated the writer to make an investigation into the
relative dimensions of the anterior portion of the cranial base in the
White and Negro races. He chose the nasion-pituitary length torepresent this portion of the cranial base in preference to the glabella-pituitary, owing to the extreme variations in the dimensions of the frontal
sinuses which create corresponding fluctuations in this measurement.
I n comparison with it the nasion-pituitary length is more stable.
The writer was astonished to find that there was a definite increase in
the mean nasion-pituitary length in the White races, as compared with
the Negro. Moreover, this lengthening was found t o be consistent for
the two sexes. The increases were slight-1 mm. in the females, and 1.5
am.in the males, but their definite and consistent character merited an
exhaustive investigation. (See Table 1.)
TABLE 1.
To SHOW
THAT, THOUGH
THE AVERAGE
DISTANCE
FROM TEE NASIONTO THE BASION
I S LESS IN THE AMERICANWHITE THAN I N THE AMERICAN
NEGRO,YET THE
ANTERIOR BASALMEASUREMENT
REPRESENTED
BY THE NASION-PITUITARY
LENGTHIS GREATERIN THE WHITE RACES. IT WILL BE NOTEDTHAT THESE
ARE COXSISTENT
FOR BOTHMALESAND FEMALES.
RESULTS
Mean nasion-hsion lenath
Female White.. . . . . . . . . . . . . .
Female Negro. . . . . . . . . . . . . . .
Male White. . . . . . . . . . . . . . . . .
Male Negro. . . . . . . . . . . . . . . . .
94.8 mm.
95.9 mm.
100.0 mm.
100.5 mm.
Mean nasion-pituitary length
58.5 mm.
57.5 mm.
61.0 mm.
59.5 mm.
CRANIOMETRIC STUDIES
339
The problem that has to be dealt with in this paper is thus somewhat anomalous. How are we to explain a lengthening of the nasionpituitary length in the White races, in view of the fact that there is an
actual shortening of the nasion-basion length ?
The collection of crania in the Hamann Museum, Western Reserve
University, was again made use of, and the writer wishes to thank Professor T. Wingate Todd for the free use of that material. 599 crania were
utilized consisting of 358 male White, 153 male Negro, 51 female White
and 37 female Negro.
The writer wishes to mention that the pituitary point was selected by
himself for craniometric purposes. The reasons for and against that
selection have been detailed in a premous communication (1).
A possible clue to this alleged lengthening of the anterior part of the
cranial base is provided by an investigation into the evolution of the
brain and particularly its frontal lobes. In this relationship it is convenient to mention at this stage a statement made on this subject by the
writer (2) eight years ago.-"There are two great factors in operation
during the evolution of the frontal region of the skull. The first is a
gradual increase in the size of the bregmatic angle, while the second is
superadded to this in the form of a concomitant bulging outwards and
forwards of the frontal cranial arc, rather after the fashion of the way in
which an archer bends his strongbow."
It is clear from what has been just stated that there is a progressive
forcing upwards of the frontal arc of the cranial roof by the developing
frontal lobes of the brain, the idea being t o provide more accommodation for the evolutionary expansion of the cerebral hemispheres. This
quadrant of the skull certainly provides us with a vivid mental picture of
the reciprocal adaptation of the skull to its cerebral contents. As the
writer (3) says in a previous paper-'% must always be borne in mind
that the skull is simply an osseous box for the reception of the brain and
its membranes, and as such is forced to adapt itself to the growth of its
contents during embryonic life. Therefore the development of the brain
absolutely determines not only the size but also the shape of the box, the
design and architecture of the latter being entirely controlled by the expansion of its cerebral contents."
The main purpose of this paper, is to show that, in addition to a raising of the roof of the frontal cranial arc there is also a lengthening of the
floor. This idea is demonstrated in Fig. 2, where it will be noticed that,
acting from the pituitary point as an arbitrary fixed point, there is expansion in the directions indicated by the four arrows. In this figure the
340
JOHN CAMERON
outline of the outer surface of a European type of skull has been superimposed upon that of a Melanesian type, both having been previously
brought to the same standard scale of measurement. This plan seemed
to illustrate in a vivid manner this idea of the “raising of the cranial
roof.” It will be observed that the line directed vertically upwards from
the pituitary point reached the vertex just in front of the bregma in
both crania. The exact relation of this line to the bregma will have to be
postponed until a sufficient number of mesially sectioned crania are
available for study. It is essential, however, that attention be directed
at this point to this important relationship.
Fig. 2. In the evolution of the skull there is expansion in all the directions
indicated by the arrows. Note that the “raising of the cranial roof”
occurs almost entirely in front of the bregma.
The significant point brought out in this communication is, that the
raising of the cranial roof which occurs in higher races takes place for the
most part in front of the bregma. This was confirmed by a study of the
auricular height of the Hamann Museum crania, as recorded by Win-
CRANIOMETRIC STUDIES
341
gate Todd (4). In Table X I on page 166 of his memoir it will be noted
that the mean cranial height in the male Whites was 116.4 mm. and in
the male Negroes 115.5 mm.-a difference of only 0.9 mm. I n the case
of the females the difference was found to be even less, the mean cranial
height in the female Whites being 112.29mm. and in the female Negroes
112.20mm.-a differencein favour of the Whites of only 0.09 mm. It is
therefore clear that we are forced to go in front of that vertical plane to
find an expansion of the cranial roof to provide accommodation for the
greater size of the brain in the white races. It does not take place posterior to that plane. Thus we revert to the very fundamental fact
stated by the writer (2) in a previous communication-“the growth and
expansion of the skull both tell us that the frontal lobes of the brain are
amongst the last parts of that organ to complete their evolutionary
history. ’’
The writer thought it well to investigate the cranial heights of the
White and Negro races as given in the Royal College of Surgeons Museum Catalogue. It may be noted that in this instance the basion-bregma
measurement was utilized to represent the cranial height.
The male Anglo-Keltic skulls of this collection were contrasted with
the male African Negro crania. In the British series, numbered 288 to
349 in the catalogue, it was found that 44 skulls were definitely adult
male. The range of variability of the cranial height in this group was
from a maximum of 145 mm. to a very low minimum of 119 mm. with an
average of 133.2 mm.
Fifty male African Negro crania in the catalogue series 1219 to 1257
were contrasted with the Anglo-Keltic types. In the Negro group the
range of variation of the cranial height was from a maximum of 146 mm.
to a minimum of 123 mm., with a mean of 136’7mm.
It will be noted in the first place that just as in the case of the Hamann
Museum collection, the range of variation was generally greatest in the
White crania. This was an outstanding feature of the writer’s first
three craniometric studies.
In the second place it will be observed that the mean cranial height of
the African Negro skull is much greater than that of the Anglo-Keltic
cranium, as opposed to a very slight superiority of the American White
over the American Negro cranial height. This may be partly due to the
difference in method employed in the two collections of crania, but the
contrast is so outstanding that other explanations will have to be looked
for.
842
.JOHN CAMERON
In the meantime, one fact stands out clearly, namely, that the mean
cranial height of the Negro skull may actually surpass that of the White
cranium, so that the demand is all the greater for an increase in the
dimensions of the frontal segment, not only in a vertical but also in a
horizontal direction, in order to provide accommodation for the evolutionary activity of the frontal lobes of the brain. Therefore it is
highly probable that the lengthening of the nasion-pituitary line in the
White races is part of this scheme of evolutionary expansion.
CONCLUSIONS
1. There is a definite increase in the mean nasion-pituitary length in
the White races as compared with the Negro.
2. This lengthening is consistent for the two sexes.
3. This lengthening is probably due to the evolutionary expansion of
the frontal lobes of the brain.
4. The mean cranial height of the Negro skull may actually exceed
that of the White, so that the demand is all the greater for an increase in
the dimensions of the frontal segment, not only in a vertical but also in
a horizontal direction, in order to provide accommodation for the evolutionary activity of the frontal lobes of the brain.
5. It is highly probable that the lengthening of the nasion-pituitary
line in the White races is part of this scheme of evolutionary expansion.
REFERENCES
1. Cameron (John)-The Cranio-facial Axis of Huxley, Pt. 11, Tr. Roy. SOC.Can.,
Third Ser., 1925, XIX.
2. Cameron (John)-A Contribution to the Evolution and Morphology of the Skull.
Tr. Roy. SOC.Can., Third Ser., 1918, XII.
3. Cameron (John)-The Cranio-facial Axis of Huxley, Pt. I. Tr. Roy. SOC.Cam,
Third Ser., 1924, XVIII.
4. Todd (T. Wingate)-Cranial Capacity and Linear Dimensions in White and
Negro. Am. J . Phys. Anthrop., 1923, VI, No. 2.
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