Anna Catherina Oettle

Age Estimation from Sternal Ends of Ribs by Phase Analysis in South African Blacks

The sternal ends of ribs are used in age determination of unknown adult remains. Standards for American populations have been described and tested. The method described by Işcan et al. is reviewed and compared with other age markers of the human skeleton. Three hundred and thirty-nine (265 male, 74 female) sternal ends of right fourth ribs, belonging to black individuals deceased in the Gauteng Province of South Africa, were collected during 1994, 1995, and 1996. Three South African investigators applied the existing method and found the repeatability among them acceptable, although the method was less accurate to predict age in this population. New phases with adjusted criteria and age ranges were developed specifically for the South African black population. A tendency toward delayed maturation was found, as well as a diversion of the appearance of female ribs perimenopausally. Future studies involving more individuals in the older age ranges, and females of all ages, could broaden the representativeness of these phases.

Geometric morphometric analysis of the use of mandibular gonial eversion in sex determination.

Physical anthropologists are continually looking for new ways to determine sex from skeletal remains. Determination of sex is done either metrically or descriptively (morphologically). Many characteristics cannot be metrically assessed and descriptive characteristics cannot always be objectively compared. Geometric morphometrics is a relatively new method that provides a mechanism to quantify descriptive morphological characteristics and provides statistics to interpret findings. In this study gonial eversion as a sexually dimorphic trait was re-evaluated, with the use of geometric morphometrics. Twenty-eight adult black female mandibles and 46 adult black male mandibles from South Africa were used. Photographs were taken of the posterior aspect of each mandible with a digital camera in a fixed position. The mandibles were positioned so as to optimise the demonstration of the gonial eversion.The captured electronic images (in jpg format) were then analysed with the tps series of programs (thin-plate spline analysis of digitized landmarks). Statistical analysis revealed that 71.4% of females and 73.9% of males could be accurately sexed by using the shape of the posterior aspect of the mandible. The males had a more variable shape, while the females were more similar to each other. A smaller gonial eversion involving the lower part of the mandibular ramus was seen in the females while the males tend to have a uniform and much wider curve involving the whole ramus. There was, however, considerable overlap between the sexes. Although different tendencies exist between the gonial eversion of the mandible of males and females, the extent of these differences is not adequate to predict the sex of a single individual.

The influence of age, sex, population group, and dentition on the mandibular angle as measured on a South African sample

The mandibular angle is measured in physical anthropological assessments of human remains to possibly assist with the determination of sex and population affinity. The purpose of this investigation was to establish how the mandibular angle changes with age and loss of teeth among the sexes in South African population groups. The angles of 653 dried adult mandibles from the Pretoria Bone Collection were measured with a mandibulometer. Males and females of both South African whites and blacks were included. To compensate for imbalances in numbers among subgroups, type IV ANOVA testing was applied. No association was found between age and angle within either of the populations, within sexes, or within dentition groups. The angle was the most obtuse in individuals without molars and with an uneven distribution of molars, and most acute in the group with an even distribution of molars on both sides. Statistically significant differences (P < 0.001) were found in the angle between the two population groups and sexes in the overall sample as well as in the subgroup with absent molar teeth (P = 0.003 for sex, males more acute angle, and P = 0.001 for population group, blacks more acute angle), although a very large overlap existed. No significant differences could be demonstrated between the sexes or populations within the subgroups with molars. We concluded that the loss of molars, especially if complete or uneven, has a considerable effect on the mandibular angle. In the assessment of human remains, the mandibular angle is not very usable in determining sex.

The midline mandibular lingual canal: importance in implant surgery.

PURPOSE The study aims to determine if midline mandibular dental implants pose a risk for the midline lingual canal (MLC). MATERIALS AND METHODS Cone beam computed tomography was used to scan 122 mandibles (31 black males; 28 black females; 32 white males and 31 white females). Midsagittal sections in the reconstructed images were made. A measurement of 6 mm across bucco-lingually was delineated as the minimum dimensions for implant placement. In dentate cases with a bucco-lingual distance in excess of 6 mm, the measurement was across the apex of the socket to determine the bone dimension available below the socket for implant placement. From these markers a vertical line was dropped to the MLC to measure the available bone. RESULTS The MLC was a consistent finding. A statistical significant difference in bone availability among the sexes and dentition pattern was found, indicating that midline implants in edentulous females posed a risk of injury to the vessels of the MLC. CONCLUSION Implants in the position of lower central incisors are regarded as a safe procedure. Clinicians should however take note of the position of the midline mandibular lingual canal and approach this area with caution, especially if the alveolar ridge is to be reduced before implant placement.

An assessment of early mandibular growth

Quantification of skeletal data has been shown to be an effective and reliable method of demonstrating variation in human growth as well as for monitoring and interpreting growth. In South Africa as well as internationally, few researchers have assessed mandibular growth in late fetal period and early childhood and therefore standards for growth and age determination in these groups are limited. The purpose of this study was to evaluate growth in the mandible from the period of 31 gestational weeks to 36 months postnatal. A total of 74 mandibles were used. Dried mandibles were sourced from the Raymond A. Dart Collection (University of Witwatersrand), and cadaveric remains were obtained from the Universities of Pretoria and the Witwatersrand. The sample was divided into four groups; 31-40 gestational weeks (group 1), 0-11 months (group 2), 12-24 months (group 3), and 25-36 months (group 4). Twenty-one osteological landmarks were digitized using a MicroScribe G2. Ten standard measurements were created and included: the maximum length of mandible, mandibular body length and width, mandibular notch width and depth, mental foramen to inferior border of mandible, mandibular basilar widths bigonial and biantegonial, bigonial width of mental foramen and mental angle. Data were analyzed using PAST statistical software and Morphologika2 v2.5. Statistically significant differences were noted in the linear measurements for all group comparisons except between groups 3 and 4. The mandible morphologically changed from a round, smooth contour anteriorly to adopt a more sharp and narrow adult shape. A progressive increase in the depth and definition of the mandibular arch was also noted. In conclusion, the mandible initially grows to accommodate the developing tongue (up to 11 months), progressive dental eruption and mastication from 12 to 36 months. Mastication is associated with muscle mass development; this would necessitate an increase in the dimensions of the mandibular notch and associated muscle attachment sites. These findings might be valuable in the estimation of age in unidentified individuals and to monitor prenatal growth of the mandible for the early diagnosis of conditions associated with stunted mandibular growth.

The Pudendal Nerve and Its Branches in Relation to Richter's Procedure

Objective: Variations in the branching pattern of the pudendal nerve (PN) have been described in the literature. This study investigated these variations in order to comment on a safe area for the placement of a Richters stitch. Methods: Richters procedure was performed on nine unembalmed female cadavers and followed by dissection. PN dissections were done on another 20 embalmed female cadavers. Variations in the branching pattern of the PN were noted and the distance between the Richters stitch placed and the PN/or the inferior rectal nerve (IRN) measured. Results: The IRN entered the gluteal region as a separate structure in 6/29 cases. The separate IRN was found to pass between 4.1 and 14.45 mm medial to the ischial spine in 18/29 cases. In one case, the Richters stitch was found to pierce the IRN. The distance between the stitch and the PN and/or the IRN ranged from 0 to 17.8 mm. Conclusions: To minimize the risk of nerve damage or entrapment, the Richters stitch should be placed >20 mm from the ischial spine. This recommended area should be revised for different population groups, as variations might exist between groups.

Ancestral Variations in the Shape and Size of the Zygoma.

The variable development of the zygoma, dictating its shape and size variations among ancestral groups, has important clinical implications and valuable anthropological and evolutionary inferences. The purpose of the study was to review the literature regarding the variations in the zygoma with ancestry. Ancestral variation in the zygoma reflects genetic variations because of genetic drift as well as natural selection and epigenetic changes to adapt to diet and climate variations with possible intensification by isolation. Prominence of the zygoma, zygomaxillary tuberosity, and malar tubercle have been associated with Eastern Asian populations in whom these features intensified. Prominence of the zygoma is also associated with groups from Eastern Europe and the rest of Asia. Diffusion of these traits occurred across the Behring Sea to the Arctic areas and to North and South America. The greatest zygomatic projections are exhibited in Arctic groups as an adaptation to extreme cold conditions, while Native South American groups also present with other features of facial robusticity. Groups from Australia, Malaysia, and Oceania show prominence of the zygoma to a certain extent, possibly because of archaic occupations by undifferentiated Southeast Asian populations. More recent interactions with Chinese groups might explain the prominent cheekbones noted in certain South African groups. Many deductions regarding evolutionary processes and diversifications of early groups have been made. Cognisance of these ancestral variations also have implications for forensic anthropological assessments as well as plastic and reconstructive surgery. More studies are needed to improve accuracy of forensic anthropological identification techniques. Anat Rec, 300:196–208, 2017.

Intra-individual metameric variation expressed at the enamel-dentine junction of lower post-canine dentition of South African fossil hominins and modern humans

OBJECTIVES The aim of this study is to compare the degree and patterning of inter- and intra-individual metameric variation in South African australopiths, early Homo and modern humans. Metameric variation likely reflects developmental and taxonomical issues, and could also be used to infer ecological and functional adaptations. However, its patterning along the early hominin postcanine dentition, particularly among South African fossil hominins, remains unexplored. MATERIALS AND METHODS Using microfocus X-ray computed tomography (µXCT) and geometric morphometric tools, we studied the enamel-dentine junction (EDJ) morphology and we investigated the intra- and inter-individual EDJ metameric variation among eight australopiths and two early Homo specimens from South Africa, as well as 32 modern humans. RESULTS Along post-canine dentition, shape changes between metameres represented by relative positions and height of dentine horns, outlines of the EDJ occlusal table are reported in modern and fossil taxa. Comparisons of EDJ mean shapes and multivariate analyses reveal substantial variation in the direction and magnitude of metameric shape changes among taxa, but some common trends can be found. In modern humans, both the direction and magnitude of metameric shape change show increased variability in M2 -M3 compared to M1 -M2 . Fossil specimens are clustered together showing similar magnitudes of shape change. Along M2 -M3 , the lengths of their metameric vectors are not as variable as those of modern humans, but they display considerable variability in the direction of shape change. CONCLUSION The distalward increase of metameric variation along the modern human molar row is consistent with the odontogenetic models of molar row structure (inhibitory cascade model). Though much remains to be tested, the variable trends and magnitudes in metamerism in fossil hominins reported here, together with differences in the scale of shape change between modern humans and fossil hominins may provide valuable information regarding functional morphology and developmental processes in fossil species.

Surgical anatomy of the pudendal nerve and its branches in South Africans

Dissection of the pudendal nerve (PN) and its branches in 71 cadavers revealed anatomic variations not previously described. Knowledge of this variation is necessary to prevent nerve injury resulting in sexual of sensory dysfunction. Because descriptions vary, this study re-evaluated the anatomy of the PN as implicated in perineal procedures in South Africans. The course of the PN from the gluteal region into the perineum was dissected in an adult sample of both sexes and of African and European ancestry. Distances between PN and branches to applicable landmarks were measured. Basic descriptive statistics and comparisons were carried out between groups. In 5/13 African females, the inferior rectal nerve (IRN) entered the gluteal region separately and in 12/13 cases it passed medial to the ischial spine with the PN. The dorsal nerve of the clitoris or penis (DNC/DNP) was closer to the bony frame in those of European ancestry. The IRN branches were more superficial in females, but deeper in males of European ancestry. In African females, a PN block and Richter stitch should be placed more medial. Outside-in transobturator tape procedures might endanger the DNC/DNP in obese individuals. In females of European ancestry the IRN branches are compromised during ischioanal abscess drainage. In males of European ancestry, the dorsal penile nerve block might be less effective. Predictions should be verified clinically.

The endocranial shape of Australopithecus africanus: surface analysis of the endocasts of Sts 5 and Sts 60

Assessment of global endocranial morphology and regional neuroanatomical changes in early hominins is critical for the reconstruction of evolutionary trajectories of cerebral regions in the human lineage. Early evidence of cortical reorganization in specific local areas (e.g. visual cortex, inferior frontal gyrus) is perceptible in the non‐human South African hominin fossil record. However, to date, little information is available regarding potential global changes in the early hominin brain. The introduction of non‐invasive imaging techniques opens up new perspectives for the study of hominin brain evolution. In this context, our primary aim in this study is to explore the organization of the Australopithecus africanus endocasts, and highlight the nature and extent of the differences distinguishing A. africanus from the extant hominids at both local and global scales. By means of X‐ray‐based imaging techniques, we investigate two A. africanus specimens from Sterkfontein Member 4, catalogued as Sts 5 and Sts 60, respectively a complete cranium and a partial cranial endocast. Endocrania were virtually reconstructed and compared by using a landmark‐free registration method based on smooth and invertible surface deformation. Both local and global information provided by our deformation‐based approach are used to perform statistical analyses and topological mapping of inter‐specific variation. Statistical analyses indicate that the endocranial shape of Sts 5 and Sts 60 approximates the Pan condition. Furthermore, our study reveals substantial differences with respect to the extant human condition, particularly in the parietal regions. Compared with Pan, the endocranial shape of the fossil specimens differs in the anterior part of the frontal gyri.