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.
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.