THE SKULL AND BRAIN
Scaphocephaly popularly misinterpreted—Sutures and
_wormian bones_ Dolichocephaly—Tasmanian skulls more
globose—Forehead occasionally well developed—Absence of
_tubera frontalia_—Fronto-squamous articulation—Occipital
peculiarities—Massive skull-walls—Cranial capacity—The
brain—Generally well developed—Important primitive
characteristics—Rhinal fissure—Insertions of neck-muscles in
occiput—Atlanto-occipital articulation.
Opinion is often expressed that the Australian has not sufficient brains
to completely fill his brain-box! Such a statement is, of course, not in
accordance with fact. A condition known as _scaphocephaly_ is, however,
not infrequently observed in the Australian skull, which gives one the
impression of insufficient inflation of the cranial vault as a whole.
A sagittal ridge is present which, with a little exaggeration, might
be likened to an inverted boat (Plate V). A similar frontal ridge is
also occasionally observed in the Negroid skull and some of the fossil
calvaria, but rarely in the modern European and Asiatic races.
This median frontal ridge is not the result of any abnormal thickening
of bone locally, but anthropologists believe it may be connected with
the early fusion of the frontal suture. As a matter of fact, the frontal
suture is extremely rare in adult primitive peoples’ skulls, and so far
only three have been recorded in the Australian by Dr. Ramsay Smith in
specimens from the Northern Territory; one case has been found in the
Tasmanian; and one or two in the Torres Strait Islanders. All the other
sutures in the calvarium seem to be less complicated in the Australian
than in the European and other more highly developed types of man; the
most complex is the lambdoid suture; and it often has one or more
small _Wormian_ bones interposed within its course, which are, in all
probability, connected with the growth of the brain, and with the
consequent enlarging processes, which the enclosing bones have suffered.
An _os inca_ is occasionally seen.
Although scaphocephalic skulls are not rare among the Australians, we
must not overlook the fact that occasionally we find specimens, dead
or alive, exhibiting sagittal curves in no wise behind those of modern
peoples. And this seems to have been even more conspicuous in the case of
the lost Tasmanians.
The Australian skull is remarkably narrow and long, in most instances
_dolichocephalic_. In the Tasmanians, the parietal portion is
considerably wider in proportion; the whole of that region seems to
be inflated, when compared with the frontal portion. Whereas in the
Australian we noticed a sagittal ridge, a peculiar median sulcus is
usually present in male skulls, running along the line of the sagittal
suture.
There is a remarkable uniformity in the contours of the male Tasmanian
skulls. They resemble the female Australian much more than they do the
male Australian, principally because the adult male Australian skulls
vary so.
We have already referred to the sloping forehead and frontal region of
the Australian skull; such is observed also in the Tasmanian and, for
that matter, in all primitive men whether they be recent or fossil. But
at the same time, one frequently observes crania of these primitive
people in which the contours of the frontals are as steep as in any
average European. The last remark applies especially to the female skull,
which even might occasionally show a combination of a prominent forehead
with a primitive superciliary ridge. The two conspicuous eminences of
the forehead of the European skull, known as the _tubera frontalia_, one
of which is situated over either eye-socket, are not developed in the
Australian or Tasmanian.
The frontal bone of the Australian skull often lies in direct contact
with the _squamous_ portion; this is, however, the case in other
primitive races also. The articulation between the bones mentioned is
effected by means of a process which the squamous bone sends towards the
frontal; the actual line of contact measuring several millimetres. In
other instances the connecting process is replaced by a small epipteric
bone. The articulation may occur on one or both sides of the skull.
The bony tuberosity of the occipital bone, being part of a
muscle-attachment, varies appreciably in its position; its central point
is anthropologically styled the _external inion_. A similar protuberance
on the inner surface of the bone is the divisional line between the great
and small hemispheres of the brain; it is called the _internal inion_.
The internal inion is, as a rule, situated lower than the external in the
adult Australian; but in female and immature skulls the two points are at
about the same level.
The angle which is contained by the occipital bone at the inion, in a
sagittal plane, is less in the Australian than in the modern European
skull. Many of the Australian skulls one examines, therefore, seem to be
unusually flattened at the base, below the inion.
The cranial walls of no other race are so massive as those of the
Australian. It is particularly in the supraorbital and the occipital
regions that the bone is so thick; the thinnest portions lie in the
temporal and lower parietals; these remarks apply principally to the
adult male skulls. The consequent strength of the aboriginal’s skull
has almost become proverbial. Many are the club-duels which tribal law
and honour demand to be fought. Upon these occasions the head is the
mark. But also in the settlement of his domestic affairs, when a serious
offence calls for punishment, the husband selects the head of his gin
for beating with the weighty nulla-nulla. Is it a wonder, then, that
one often finds the skulls of aborigines covered with dents, which have
resulted from such a battering? Occasionally death might follow such
treatment; and a few cases stand on record of blindness following the
destruction of the centre of vision by a blow from the club. So severe
is the impact that often, in the stillness of night, I have heard the
falling of the blows upon a disobedient gin’s head, although our camp
might have been some considerable distance off.
[Illustration: _PLATE V_
Wordaman man, profile and full-face.
Note _scaphocephaly_, great width of nose, and strong naso-labial fold.]
This wonderful strength is largely due to the better development of
the compact tissue of the skull-bone, when compared with that of the
European. The external, as well as the internal, laminae of the cranial
wall are thicker than ours, while, on the other hand, the intermediate
layer, known as the _diploë_, is thinner in the aboriginal’s skull. This
condition serves the double purpose of protecting the brain against the
mechanical injury referred to, as well as against the powerful rays of a
fierce southern sun.
In regard to the cubic capacity of the Tasmanian and Australian skulls,
we might accept as averages for the adult male and female Australian
skulls 1,290 and 1,845 cubic centimeters respectively, and as similar
averages for the Tasmanian, 1,315 and 1,155 respectively. The individual
variations in the adult male Australian skulls range from 1,630 to 1,040,
and in those of the opposite sex from 1,280 to 1,010 cubic centimeters.
The corresponding variations in male and female Tasmanian skulls are from
1,465 to 1,140, and from 1,225 to 1,060 respectively.
There are, however, considerable variations in the capacity of Australian
skulls; many instances may be selected in which the capacity is quite as
good as that of an ordinary European brain-box. On the other hand, cases
have been recorded of capacities not greater than 940 cubic centimeters
in adult female Australian skulls.
The brain of the Australian has not been studied to any considerable
extent. The first impression a layman receives, upon beholding the
brain of an aboriginal, is, perhaps, a little disappointing. Assuming
him to be a man of low intellect, he expects to find a brain of
inferior development. But such is not the case. In fact, to any but
the specialist, there seems nothing to indicate a lowly intellectual
capacity. The number of convolutions is about the same as one finds
in Europeans of average intelligence; but the structure, as a whole,
is, perhaps, a little less complicated and less tortuous than we are
accustomed to see in our own sort. The large cerebral hemispheres
completely cover the cerebellum. Certain features, like the operculum,
are more strongly developed on the left side than the right.
In some respects the Australian brain preserves important
characteristics, which indicate the genesis of the more modified or more
specialized conditions seen in the brain of modern man. The length of
the hemispheres and the small occipital development are unquestionably
extremely primitive characters, which, among others, remind us of the
common ancestry of man and ape. In the brains of the more cultured
peoples, processes are at work, which are completely remodelling portions
of the important organ, and thereby making it more and more unlike the
anthropoid or simian brain. By such modifications in the occipital
region, the human brain is gradually ridding itself of a feature strongly
developed in the monkey’s brain, which has been named the _sulcus
lunatus_. German anthropologists call this sulcus “_Affenspalte_,” which
means “_Monkey-Cleft_,” i.e., a cleft or sulcus in the posterior portion
of the brain of primates, which is strongly developed in the monkeys,
but disappearing in the brain of man. In the Australian’s brain, the
_sulcus lunatus_ can often be more or less distinctly discerned, and its
presence there affords us valuable evidence when tracing the remnants of
the sulcus in the brains of other races, including those of the modern
Europeans.
The posterior lip of the _sulcus lunatus_ is occasionally operculated
in the Australian’s brain. In the parieto-occipital region, the outer
convolutions are depressed and covered by an operculum-like flap; but
this condition is also occasionally observed in European examples.
Another simian feature, rarely seen in European brains, is rather
frequently found in Australian, in the shape of a _rhinal fissure_. It
should be observed, however, that the European embryo clearly shows this
fissure in the brain as it is developing.
The occipital bone varies in its appearance. The impressions made upon
the surface, where, during the life-time of an individual, the strong
muscles of the neck were attached, are, as a rule, well developed. The
minor _posterior-rectus_ and _complexus_ muscles of the neck often leave
deep hollows in the occipital bone at the points of their insertions.
A bony process is often noticed in front of the big foramen, which joins
the occipital condyles; this is an atavistic condition, by means of which
an extra articulation is occasionally effected between the occiput and
vertebral column. The condyles vary considerably in their elevation above
the occipital bone. The large foramen is mostly oval in shape, but often
has a little median notch in its posterior margin.