Postnatal growth of the frontal and parietal bones in white males

New craniodental fossils of Paranthropus robustus from Kromdraai, South Africa (2014-2017 excavations)

Since the initial discovery of Paranthropus robustus at the site of Kromdraai in 1938, the hypodigm of this species has been expanded by subsequent work at the localities of Swartkrans and Drimolen, with a few fossils also known from Cooper's D, Gondolin and Sterkfontein Member 5. Beginning in 2014, systematic excavations at Kromdraai uncovered a large and previously unknown fossiliferous area, shedding light on Units O and P in the earliest part of the site's stratigraphic sequence. The aim of this paper is to provide detailed descriptions and illustrations of 30 P. robustus craniodental specimens recovered between 2014 and 2017 within the Unit P deposits at Kromdraai. This new sample predates all prior conspecific specimens found at this site (including the holotype of P. robustus from Kromdraai, TM 1517). Its basic dental morphology dimensions and cranial features are compared in a preliminary analysis with other P. robustus samples. The P. robustus sample from Kromdraai Unit P documents previously unknown portions of the P. robustus juvenile cranium. The new dental and cranial remains aid in the exploration of potential morphological distinctions between site-specific P. robustus samples and are compared favorably in size and morphology with the small P. robustus specimens from Drimolen (e.g., DNH 7). These findings do not support the hypothesis that the specimens from Drimolen belong to a different taxonomic group. Instead, they reinforce the presence of a significant degree of sexual dimorphism within P. robustus. The Kromdraai Unit P specimens also contribute to the biodemographic profile of P. robustus. The notable prevalence of infants (i.e., juvenile individuals before the emergence of their first permanent molars) mirrors the natural mortality profiles observed in wild chimpanzees. This suggests a closer resemblance in the processes of accumulation in Kromdraai Unit P and Drimolen than at Swartkrans.

Age estimation of immature human skeletal remains from mandibular and cranial bone dimensions in the postnatal period

Age estimation is one of the crucial first steps in the identification of human skeletal remains in both forensic and archeological contexts. In the postnatal period, age is traditionally estimated from dental development or skeletal growth, typically long bone diaphyseal length. However, in many occasions other methods are required. This study provides alternative means of estimating age of juvenile remains from the size of several cranial bones and the mandible. A sample of 185 identified juvenile skeletons between birth and 13 years of age from two European collections were used (Lisbon and Spitalfields). Measurements of the frontal, occipital-lateralis, occipital-basilaris, occipital-squamous, zygomatic, maxilla, and mandible were used to calculate classical calibration regression formulae for the sexes combined. The sample was divided into three age groups birth-2 years, 2-6 years, and 2-12.9 years, depending on bone and its growth trajectory. For all the bones, measurements of the youngest age groups yielded the most precise age estimates. The vault bones on average yielded the best performing models, with the frontal bone having the most precise of all. The mandible performed on par with the best performing cranial bones, particularly in individuals under the age of 2 years. This study provides one of the most comprehensive approaches to juvenile age estimation based on bones of the skull, providing a resource that potentially can help estimate age of juvenile skeletons from a variety of circumstances.

Midfacial growth patterns in males from newborn to 5 years old based on computed tomography

OBJECTIVES

Growth patterns of the human facial skeleton have been of great interest and importance for biological anthropologists, forensic scientists, craniofacial surgeons, and orthopedists. Nevertheless, growth trends of the facial skeleton in infancy and early childhood are still poorly known and clinical CT data have been insufficiently used for studying craniofacial ontogeny. The purpose of this study was to provide a comprehensive quantitative description of human midfacial ontogeny in infancy and early childhood, and to contribute to debates regarding the role of modularity vs. integration in shaping the human face.

METHODS

Our dataset includes 146 high resolution clinical CT datasets of males from the 2nd to 6th years of life and 101 dataset of infants (males) in the 1st year of life. Forty landmarks were collected from each 3D reconstructed skull, then 25 linear measurements describing the morphological features of the facial skeleton were calculated. The integration/modularity issue was addressed via comparison of intragroup correlation matrices at different ages.

RESULTS

Growth trends for all the measurements are presented in charts and tables of statistical parameters that can be used as normative data. The midfacial variables display a great diversity of growth patterns. The correlation structure of the measurements is different at different ages.

CONCLUSIONS

Variables commonly assigned to the same unit of the facial skeleton can exhibit rather different growth trends, but some measurements display seemingly coordinated patterns of growth change. The level of interindividual variation of most measurements is stable after the second half of the first year of life.

Human cranial vault thickness in a contemporary sample of 1097 autopsy cases: relation to body weight, stature, age, sex and ancestry

The relation between human cranial vault thickness (CVT) and various elements of the physical anthropological biological profile is subject of ongoing discussion. Some results seem to indicate no correlation between CVT and the biological profile of the individual, whereas other results suggest that CVT measurements might be useful for identification purposes. This study assesses the correlation between CVT and body weight, stature, age, sex, and ancestry by reviewing data of 1097 forensic autopsies performed at the Netherlands Forensic Institute (NFI). In subadults (younger than 19 years of age at the time of death), all frontal, temporal, and occipital CVT measurements correlated moderately to strongly with indicators of growth (body weight, stature, and age). Neither sex nor ancestry correlated significantly with cranial thickness. In adults, body weight correlated with all CVT measurements. No meaningful correlation was found between CVT and stature or age. Females showed to have thicker frontal bones, and the occipital region was thicker in the Negroid subsample. All correlation in the adult group was weak, with the distribution of cranial thickness overlapping for a great deal between the groups. Based on these results, it was concluded that CVT generally cannot be used as an indicator for any part of the biological profile.

Skull bone thickness versus malocclusion

Objective

The objectives of this study were to determine the thickness of skull bones, namely frontal, parietal, and occipital bones in Class I, Class II, and Class III patients.

Materials and Methods

Three hundred subjects who reported to the Department of Orthodontics requiring orthodontic treatment within the age group 17-35 were selected for the study. They were subdivided into three groups of 100 each according to the skeletal and dental relation. Profile radiographs were taken and the tracings were then scanned, and uploaded to the MATLAB 7.6.0 (R 2008a) software. The total surface areas of the individual bones were estimated by the software, which represented the thickness of each bone.

Result

Frontal bone was the thickest in Class III malocclusion group and the thinnest in Class II malocclusion group. But the parietal and occipital bone thickness were not significant. During gender differentiation in Class I, malocclusion group frontal bone thickness was more in males than females, In Class II, malocclusion parietal bone thickness was more in males than females. No statistically significant difference exists between genders, in Class III malocclusion group. During inter-comparison, the frontal bone thickness was significant when compared with Class I and Class II malocclusion groups and Class II and Class III malocclusion groups.

Conclusion

The differences in skull thickness in various malocclusions can be used as an adjunct in diagnosis and treatment planning for orthodontic patients. It was found that the new method (MATLAB 7.6.0 [R 2008a] software) of measuring skull thickness was easier, faster, precise, and accurate.

Functional craniology and brain evolution: from paleontology to biomedicine

Anatomical systems are organized through a network of structural and functional relationships among their elements. This network of relationships is the result of evolution, it represents the actual target of selection, and it generates the set of rules orienting and constraining the morphogenetic processes. Understanding the relationship among cranial and cerebral components is necessary to investigate the factors that have influenced and characterized our neuroanatomy, and possible drawbacks associated with the evolution of large brains. The study of the spatial relationships between skull and brain in the human genus has direct relevance in cranial surgery. Geometrical modeling can provide functional perspectives in evolution and brain physiology, like in simulations to investigate metabolic heat production and dissipation in the endocranial form. Analysis of the evolutionary constraints between facial and neural blocks can provide new information on visual impairment. The study of brain form variation in fossil humans can supply a different perspective for interpreting the processes behind neurodegeneration and Alzheimer’s disease. Following these examples, it is apparent that paleontology and biomedicine can exchange relevant information and contribute at the same time to the development of robust evolutionary hypotheses on brain evolution, while offering more comprehensive biological perspectives with regard to the interpretation of pathological processes.

Anatomically Based Modelling of the Human Skull and Jaw

We present here an anatomically based model of the human masticatory system that provides a framework for simulating the complex chewing process. The initial motivation for creating this model was the desire to have a computational model of the human jaw that can be used to simulate the action of simple bites, and to calculate the stresses and forces on the teeth that are involved. The model created also provides a platform that can be used to investigate other features of the masticatory system. To construct this global model, individual models of the bones of the skull and jaw were created from generic data sets. Geometric models of the muscles of mastication were also created and attached to the appropriate bones. To complete this initial model, representations of the crowns of the teeth were created and a basic model of the temporomandibular joint (TMJ) was included. The finite element method was used to solve for the stresses and strains created by the loading conditions during a clenching simulation involving the mandible bone. The model presented here is also discussed in relation to a model of the entire musculo-skeletal system being developed as part of the Physiome Project.

How and why humans grow thin skulls: experimental evidence for systemic cortical robusticity

To what extent is cranial vault thickness (CVT) a character that is strongly linked to the genome, or to what extent does it reflect the activity of an individual prior to skeletal maturity? Experimental data from pigs and armadillos indicate that CVT increases more rapidly in exercised juveniles than in genetically similar controls, despite the low levels of strain generated by chewing or locomotion in the neurocranium. CVT increases in these individuals appear to be a consequence of systemic cortical bone growth induced by exercise. In addition, an analysis of the variability in vault thickness in the genus Homo demonstrates that, until the Holocene, there has been only a slight, general decrease in vault thickness over time with no consistent significant differences between archaic and early anatomically modern humans from the Late Pleistocene. Although there may be some genetic component to variation in CVT, exercise-related, non-genetically heritable stimuli appear to account for most of the variance between individuals. The thick cranial vaults of most hunter-gatherers and early agriculturalists suggests that they may have experienced higher levels of sustained exercise relative to body mass than the majority of recent, post-industrial humans.

How and why humans grow thin skulls: experimental evidence for systemic cortical robusticity

To what extent is cranial vault thickness (CVT) a character that is strongly linked to the genome, or to what extent does it reflect the activity of an individual prior to skeletal maturity? Experimental data from pigs and armadillos indicate that CVT increases more rapidly in exercised juveniles than in genetically similar controls, despite the low levels of strain generated by chewing or locomotion in the neurocranium. CVT increases in these individuals appear to be a consequence of systemic cortical bone growth induced by exercise. In addition, an analysis of the variability in vault thickness in the genus Homo demonstrates that, until the Holocene, there has been only a slight, general decrease in vault thickness over time with no consistent significant differences between archaic and early anatomically modern humans from the Late Pleistocene. Although there may be some genetic component to variation in CVT, exercise-related, non-genetically heritable stimuli appear to account for most of the variance between individuals. The thick cranial vaults of most hunter-gatherers and early agriculturalists suggests that they may have experienced higher levels of sustained exercise relative to body mass than the majority of recent, post-industrial humans.

Sutural effects of fronto-occipital cranial modification

Maya adult crania from the site of Lamanai, Belize provide a retrospective means of examining growth processes in the cranial vault. The Lamanai population practiced fronto-occipital deformation which is found to be significantly associated with premature sagittal synostosis and wormian bones of the lambdoidal suture. The undeformed members of the population also exhibit an abnormally high frequency of sagittal synostosis, but a significantly lower frequency than the deformed sample. It is suggested that the deforming apparatus creates tensile forces on the sagittal suture during the peak period of growth of the parietals, and that these forces might induce an adaptive response important in producing premature sagittal synostosis. The undeformed sample may have an increased congenital risk of sagittal synostosis created by their natural brachycephalic morphology in utero. The frequency patterning of wormian bones suggests a mixture of genetic and environmental causes in which tensile forces may also play a role.

Efficiency of cranial bilateral measurements in separating human populations

A set of 31 nonconventional paired cranial measurements, as well as six conventional nonpaired measures, were taken on 266 skulls, representing two related populations: Bedouins of the Israeli Negev Desert and Bedouins of the Sinai. The data were subjected to univariate and discriminant analyses to determine the relative efficacy of paired vs. conventional measures in sorting individuals according to tribal and sex affiliation. It was found that paired measures have greater discriminatory power (87%) than conventional ones (47%) in terms of classifying individuals belonging to human isolates derived from a common ancestor and sharing similar environmental conditions. This greater discrimination attests to the value of the level of "developmental noise" (a measure provided by fluctuating asymmetry) in sorting human populations. Possible explanations are proffered for the above finding.

Intentional cranial vault deformation and induced changes of the cranial base and face

Three morphologically distinct populations of Peruvian crania (n = 130) were metrically analysed to quantify changes resulting from intentional artificial vault deformation. Two of these samples are artificially deformed (anteroposterior [AP] and circumferential [C] types). Measurements taken from lateral radiographs demonstrated that alternative forms of the cranial base angle (N-S-Ba, planum angle, planum sphenoidale to plane of the clivus and PANG angle, planum sphenoidale to basion-sella plane) and the orbital and OANG angles (orbital roof to plane of the clivus and basion-sella plane, respectively) of both deformed groups increased while the angle S-Ba-O decreased significantly with respect to the undeformed (N) sample. Changes in the AP group are largely due to anteroinferior displacement of the basion-sella plane. Similar changes in group C are amplified by this group's posterosuperior frontal migration. This migration results in a relatively shallow orbit at the orbital plate/frontal squama interface. Unlike the deformation experienced by the external vault plates, the basion-sella plane orientation remains stable with respect to the Frankfort Horizontal. Additionally, nasal region measurements such as maximum nasal aperture breadth and nasal height were largely stable between each deformed group and the undeformed group. However, facial (bimaxillary and bizygomatic), basicranial, cranial, and frontal breadths decreased significantly from group AP to group N to group C. Thus, gross morphological facial changes between each undeformed group and the control group are largely accounted for by dimensional changes in peripheral structures. These results stress the importance of the dynamic interrelationship between the cranial vault and base in the development of the craniofacial complex.

A fossil hominid frontal from Velika Pećina (Croatia) and a consideration of Upper Pleistocene hominids from Yugoslavia

Fossil hominid remains dating to the Upper Pleistocene in Yugoslavia are reviewed. Particular emphasis is placed on the assessment of a hominid frontal from the site of Velika Pećina in northwestern Croatia. This specimen represents the earliest absolutely-dated hominid associated with the Upper Paleolithic in Europe. Also the hominid material from the site of Veternica is discussed, and data are presented on the new remains from Sandalja. It is concluded that no Neandertal remains, except for Krapina, have been found in Yugoslavia.

Thickness of the normal skull in the American Blacks and Whites

Normal skull thickness has been measured in a general hospital population of 300 blacks and 200 whites in America. In both groups, there is a rapid increase in skull thickness during the first two decades of life, followed by a small uniform increase reaching a peak in the fifth and sixth decades. The sex differences are variable, but in certain age groups the females in both races have significatly thicker parietal and occipital bones than their male counterpart. The frontal bone is thicker in the white male than in the black, and the parietooccipital thicker in the blacks than in the whites. Some suggestions are offered to explain the sex and racial difference noted.

Developmental defects in the cranial vault

The parietal bone seems to be the target for a number of different developmental conditions of the calvaria some of which are congenital whilst others develop in later life. The characteristic radiological patterns of a number of these lesions are described and illustrated, and an attempt is made to correlate the pathology with alterations in bone growth.