Secular trends in cranial morphological traits: a socioeconomic perspective of change and sexual dimorphism in North Americans 1849–1960

Estimation of sex assigned at birth using dental crown and cervical measurements in a modern global sample

Despite developing prior to the appearance of secondary sexual characteristics of the skeleton, the permanent dentition exhibits sexual dimorphism. Therefore, teeth can serve as a means to estimate sex assigned at birth even in young individuals. This project takes a large global sample of maximum dimensions of the crown as well as measurements of the crown at the cervix to explore sexual dimorphism. Dimorphism is noted in teeth throughout the dental arcade, particularly in the canines. We provide sectioning points as well as the probability of correct classification (ranging from 50.9% to 81.3%) for each measurement to aid the practitioner in sex estimation from the dentition. This research provides a method to estimate sex without arbitrary population specifications. We argue for a global approach that incorporates more population variation to remove the need to estimate "ancestry," (which in actuality is translated to a social race category) and therefore does not force sexual dimorphism-related variation into these mutable and ambiguous categories. Further, this paper demonstrates the utility of the dentition as an additional indicator to aid with the estimation of sex assigned at birth in forensic anthropology. The goal of this research is to better understand the expression of sexual dimorphism across the skeleton in a global context.

How reliable is the application of the sex classifier based on exocranial surface (Musilová et al., 2016) for geographically and temporally distant skull series

Sex estimation is one of the crucial trends in cases of findings of unknown skeletal remains in forensics and bioarchaeology. The changing nature of sexual dimorphism (population specificity, secular trend, other external and internal factors influence) brings challenges to developing new methods; and there are new aims to be independent of these changes such, as the method by Musilová et al. (2016). These methods need to be evaluated on different datasets to determine if they are truly reliable among populations from different places and times, in the case of bioarchaeology. This study assessed the application of the aforementioned method on non-European contemporary and ancient populations to identify the reliability of the method on this separate dataset. The study sample consisted of 96 CT scans of skulls from contemporary Egyptians and 54 3D models of skulls from the Egyptian Old Kingdom Period (2700-2180 BC). The classifier method, previously tested on both Czech and French populations, yielded high accuracies (over 90 %) for sex estimation. For the contemporary Egyptian skull sample, the classifier was able to determine males versus females with an 89.59 % accuracy rate and an AUC value (area under the curve - a measure of the combined specificity and sensitivity of the test) of 0.99; this proves that the classifier is reliable even with a lower degree of accuracy. Conversely, the Old Kingdom Period sample yielded a lower level of accuracy at around 70 % (61.11 %, precisely), although with an AUC value of 0.92, the result is not considered reliable.

Comparison of Morphological Sex Assessment and Genetic Sex Determination on Adult and Sub-Adult 17th-19th Century Skeletal Remains

The first step in the analysis of human skeletal remains is the establishment of the biological profile of an individual. This includes sex assessment, which depends highly on the age of the individual and on the completeness and preservation state of the remains. Macroscopic methods only provide the assessment of sex, while for sex determination, molecular methods need to be included. However, poor preservation of the remains can make molecular methods impossible and only assessment can be performed. Presented research compares DNA-determined and morphologically assessed sex of adult and non-adult individuals buried in a modern-age cemetery (17th to late 19th century) in Ljubljana, Slovenia. The aim of the study was to assess the accuracy of commonly used macroscopic methods for sex assessment on a Slovenian post-medieval population. Results demonstrate that for adults, macroscopic methods employed are highly reliable and pelvic morphology, even the sciatic notch alone, is more reliable than skull. In non-adults, macroscopic methods are not as reliable as in adults, which agrees with previous research. This study shows how morphological and molecular methods can go hand in hand when building a biological profile of an individual. On their own, each methodology presented some individuals with undetermined sex, while together, sex of all the individuals was provided. Results confirm suitability of sex assessment based on skull and especially pelvic morphology in Slovenian post-medieval adults, while in the non-adult population molecular methods are advised.

Cribra orbitalia is correlated with the meningo-orbital foramen and is vascular and developmental in nature

Cribra orbitalia is a phenomenon with interdisciplinary interest. However, the etiology of cribra orbitalia remains unclear. Recently, the appearance of cribra orbitalia was identified as vascular in nature. This study assessed the relationship between anatomical variation of vasculature, as determined by the presence of meningo-orbital foramina, and the presence of cribra orbitalia in 178 orbits. Cribra orbitalia was identified in 27.5% (49:178) of orbits (22.7%, 35:154 adult orbits and 58.3%, 14:24 subadult orbits) and meningo-orbital foramina were identified in 65.8% (100:152) of orbits. Among the 150 total intact adult orbits (i.e., orbital roof and posterior orbits both intact), cribra orbitalia was found in 35 (23.3%). Of these 35 occurrences of cribra orbitalia, 32 (91.4%) had the concurrent finding of a meningo-orbital foramen. However, in the absence of the meningo-orbital foramen, cribra orbitalia was only found in three sides out of the total sample of intact orbits (3:150; 2.0%). Fisher's exact test revealed that the presence of cribra orbitalia and the meningo-orbital foramen were statistically dependent variables (p = .0002). Visual evidence corroborated statistical findings-vascular impressions joined cribra orbitalia to meningo-orbital foramina. This study identifies that individuals who possess a meningo-orbital foramen are anatomically predisposed to developing cribra orbitalia. Conversely, cribra orbitalia is unlikely to occur in an individual who does not possess a meningo-orbital foramen. Thus, the antecedent of cribra orbitalia is both vascular and developmental in nature. This report represents an important advancement in the understanding of cribra orbitalia-there is an anatomical predisposition to the development of cribra orbitalia.

The size and shape of the human pelvis: a comparative study of modern and medieval age populations

INTRODUCTION

Great variability in shape and size of the bony pelvis can be observed in the current population, but there is not enough data on how long the historical period must elapse to gain changes in pelvic shape and size. The aim of the study was to identify morphological changes in bony pelvis in males and females after a developmentally short period of approximately one thousand years.

MATERIAL AND METHODS

Seventeen defined external dimensions of pelvic bone from 120 adult individuals (two craniocaudal, two ventrodorsal, six mediolateral, three acetabular dimensions, and four dimension of the auricular surface) were measured. The medieval sample of 60 pelvic bones (30 male and 30 female) was obtained from the Great Moravian site of Mikulčice-Valy (9th-10th century), while the modern collection of 60 pelvic bones (30 male and 30 female) dates from the late 19th and first half of the 20th centuries. Obtained results were evaluated using the independent t-test at a 5% level of significance.

RESULTS

A comparison of male and female pelvic dimensions within a single population yielded expected results: the mean male values were greater. In modern population, male pelvis mean values were greater in 15 of defined parameters, while in medieval population, male dimensions were larger in 16 variables. A comparison of modern and medieval female pelvic bones found 11 variables to be greater in medieval sample (one determining the craniocaudal dimension, five the mediolateral, all three the acetabular, and two determining the auricular surface dimensions), but only two were significant (two dimensions determining the mediolateral dimensions). In modern female samples, there were five variables greater (one determining the craniocaudal dimension, one the ventrodorsal, one the mediolateral, and two determining the auricular surface dimensions), but only two were significant as well (one determining the craniocaudal and one the ventrodorsal dimensions). A comparison of male pelvic bones found 13 variables to be greater in medieval pelvis (one determining the craniocaudal dimension, all six the mediolateral, one the ventrodorsal, all three the acetabular, and two determining the auricular surface dimensions), but only four were significant as well (all determining the mediolateral dimensions). In modern male sample, there were only four variables greater (one determining the craniocaudal dimension, one the ventrodorsal, and two determining the auricular surface dimensions), but only one was significant (determining the craniocaudal dimension).

CONCLUSION

Unexpectedly, our study did not find the early medieval population to have a smaller pelvis compared to the modern population. While pelvic bones of the former were somewhat lower, but wider, those of the latter population were a bit higher and narrower. The study allows a very careful statement that one millennium is a time period long enough for measurable morphological deviations of the pelvic bones shape and size to occur.

Effects of Multi-Generational Soft Diet Consumption on Mouse Craniofacial Morphology

Variations in craniofacial morphology may arise as a result of adaptation to different environmental factors such as soft diet (SD), which lessens functional masticatory load. Prior studies have shown that changes in the masticatory muscle function associated with a switch to short-term SD led to changes in craniofacial morphology and alveolar bone architecture. However, the long-term effects of SD and the associated adaptive changes in craniofacial shape are unclear. Our novel study set out to profile prospective skull changes in mice fed with SDs over multiple generations using three-dimensional (3D) geometric morphometric analysis (GMA). Our results revealed that short-term SD consumption led to a significant decrease in craniofacial size, along with numerous shape changes. Long-term SD consumption over 15 continuous generations was not associated with changes in craniofacial size; however, shape analysis revealed mice with shortened crania and mandibles in the anteroposterior dimension, as well as relative widening in the transverse dimension compared to the average shape of all mice analyzed in our study. Moreover, changes in shape and size associated with different functional loads appeared to be independent - shape changes persisted after diets were switched for one generation, whereas size decreased after one generation and then returned to baseline size. Our study is the first to study the role of prolonged, multi-generational SD consumption in the determination of craniofacial size and shape.

Evaluating macroscopic sex estimation methods using genetically sexed archaeological material: The medieval skeletal collection from St John's Divinity School, Cambridge

OBJECTIVES

In tests on known individuals macroscopic sex estimation has between 70% and 98% accuracy. However, materials used to create and test these methods are overwhelming modern. As sexual dimorphism is dependent on multiple factors, it is unclear whether macroscopic methods have similar success on earlier materials, which differ in lifestyle and nutrition. This research aims to assess the accuracy of commonly used traits by comparing macroscopic sex estimates to genetic sex in medieval English material.

MATERIALS AND METHODS

Sixty-six individuals from the 13th to 16th century Hospital of St John the Evangelist, Cambridge, were assessed. Genetic sex was determined using a shotgun approach. Eighteen skeletal traits were examined, and macroscopic sex estimates were derived from the os coxae, skull, and os coxae and skull combined. Each trait was tested for accuracy to explore sex estimates errors.

RESULTS

The combined estimate (97.7%) outperformed the os coxae only estimate (95.7%), which outperformed the skull only estimate (90.4%). Accuracy rates for individual traits varied: Phenice traits were most accurate, whereas supraorbital margins, frontal bossing, and gonial flaring were least accurate. The preauricular sulcus and arc compose showed a bias in accuracy between sexes.

DISCUSSION

Macroscopic sex estimates are accurate when applied to medieval material from Cambridge. However, low trait accuracy rates may relate to differences in dimorphism between the method derivative sample and the St John's collection. Given the sex bias, the preauricular sulcus, frontal bossing, and arc compose should be reconsidered as appropriate traits for sex estimation for this group.

Talking heads: Morphological variation in the human mandible over the last 500 years in the Netherlands

The primary aim of this paper is to assess patterns of morphological variation in the mandible to investigate changes during the last 500 years in the Netherlands. Three-dimensional geometric morphometrics is used on data collected from adults from three populations living in the Netherlands during three time-periods. Two of these samples come from Dutch archaeological sites (Alkmaar, 1484-1574, n=37; and Middenbeemster, 1829-1866, n=51) and were digitized using a 3D laser scanner. The third is a modern sample obtained from MRI scans of 34 modern Dutch individuals. Differences between mandibles are dominated by size. Significant differences in size are found among samples, with on average, males from Alkmaar having the largest mandibles and females from Middenbeemster having the smallest. The results are possibly linked to a softening of the diet, due to a combination of differences in food types and food processing that occurred between these time-periods. Differences in shape are most noticeable between males from Alkmaar and Middenbeemster. Shape differences between males and females are concentrated in the symphysis and ramus, which is mostly the consequence of sexual dimorphism. The relevance of this research is a better understanding of the anatomical variation of the mandible that can occur over an evolutionarily short time, as well as supporting research that has shown plasticity of the mandibular form related to diet and food processing. This plasticity of form must be taken into account in phylogenetic research and when the mandible is used in sex estimation of skeletons.