Analysis of sexual dimorphism of craniofacial traits using geometric morphometric techniques

This work deals with the assessment of cranial sexual dimorphism in human skeletal samples applying geometric morphometric techniques. The purpose of this research is to apply such techniques to quantitatively describe in craniofacial traits the degree and pattern of shape and size sexual dimorphism. Likewise, we evaluate the precision and accuracy of semilandmark‐based techniques for sex estimation. We employ a sample of 125 adult skulls of known sex from the Coimbra collection. A set of coordinate points was selected to describe glabella, mastoid, frontal and zygomatic processes. The results of intra‐class correlation coefficient (ICC) show excellent intra‐ and inter‐observer agreement (ICC > 0.96) in the location of the coordinates of points employed. The principal component analysis (PCA) performed on shape variables shows a large superposition of both sexes, suggesting a relatively low degree of dimorphism in shape. As a consequence, the average percentages of correct sex estimations based on these variables were of 60.12 and 68.90%, obtained by discriminant analysis with leave‐one‐out cross validation and k‐means clustering respectively. Conversely, when centroid size is included in PCA, females and males exhibit large separation along the first component. The highest values of correct assignment (77.86 and 72.15%) were found using shape–size variables with discriminant and k‐means clustering analysis, indicating that the traits analysed display marked sex differences related to the larger size and more robust features of males. Finally, the advantages of geometric morphometric techniques are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Three statistical methods for sex determination in extant and fossil caprines: assessment of the Rupicapra long bones

Sex determination of fossil remains in archeopaleontological contexts is a necessary step in order to gain insights in archaeological and paleobiological parameters such as prey selection and sexual dimorphism. Species with higher sexual dimorphism are more reliably sexed while the sex determination of less dimorphic animals is not attempted. In this study, we compared the accuracy of three different methods in the sex determination of a modern known-sex sample of chamois (Rupicapra pyrenaica parva) from the Cantabrian range (Northern Iberian Peninsula), which is a small-sized ungulate with low sexual dimorphism when compared to other animals in which sex determination has been attempted (i.e., Ursus spelaeus, Capra pyrenaica). The three methods applied were mixture analysis (MA), cluster analysis (CA) and principal component analysis (PCA). Within CA we applied three different analysis: one agglomerative hierarchical method (AH) and two optimal partitioning methods (k-means and robust k-means); and within PCA we applied normal and robust variants of the analysis.     

Identifying sword marks on bone: criteria for distinguishing between cut marks made by different classes of bladed weapons

Swords have been one of the major weapons used in violent conflicts for much of human history. Certain archaeological situations, especially those dealing with the recovery and analysis of battle casualties, may raise questions about what type(s) of bladed weapon was used in a particular conflict (e.g., the battle of Kamakura, Japan, AD 1333; the battle of Wisby, Sweden, AD 1361; the battle of Towton, England, AD 1461). Little work has been done, however, on developing criteria to differentiate sword cut marks from other types of cut marks, or to distinguish between marks created by different sword types. To develop such criteria, bovine tibiae (n = 7) were struck using six different types of bladed weapon and the resulting marks (n = 92) were analyzed. Eight traits describing the morphology of the cut mark – such as shape, the presence and unilateral/bilateral state of flaking and feathering, the presence of bone shards, associated breaks, etc. – are defined and related to blade type used. Sword marks were found to be easily distinguishable from knife marks. The variation in marks made by different sword types is significantly correlated with differences in blade weight (p < 0.0001), grip (p < 0.0113), and sharpness (p ≤ 0.0179). The criteria and analyses developed and implemented in this study will be of use to researchers in forensics and osteoarchaeology who want to infer bladed weapon type from marks on bones.     

A crossbeam co-ordinate caliper for the morphometric analysis of lithic nuclei: a description,test and empirical examples of application

Over the last four decades, there has been surprisingly little advance in the quantitative morphometric analysis of Palaeolithic stone tools, especially compared to that which has taken place in biological morphometrics over a comparable time frame. In Palaeolithic archaeology's sister discipline of palaeoanthropology, detailed quantitative morphometric, geometric morphometric, and even 3D geometric morphometric analyses are now seen almost as routine. This period of relative methodological stasis may have been influenced by the lack of homologous landmarks on many lithic tools (essential for any comparative analysis), especially core-based technologies of the Lower Palaeolithic. Archaeological field conditions may also prohibit the use of expensive and delicate precision instruments in certain cases. Here we present a crossbeam co-ordinate caliper that – crucially – both geometrically locates and measures distances between morphologically homologous landmarks upon lithic nuclei via a single protocol. Intra- and inter-observer error tests provide evidence that error levels associated with the instrument fall within acceptable ranges. In addition, we present empirical examples of application in the form of a multivariate analysis of 55 discrete morphometric variables, and a 3D geometric morphometric analysis of co-ordinate landmark configurations derived from Pleistocene lithic nuclei (i.e. ‘cores’ sensu lato). We also introduce to lithic studies some techniques for the study of shape variation that have previously been used with success in biological morphometric analyses. We conclude that use of an instrument such as the crossbeam co-ordinate caliper may provide a useful adjunct to traditional techniques of lithic analysis, particularly in developing a quantitative morphometric approach.     

Identification of fragmentary bone from the Pacific

We explore bone microstructure for taxonomic identification of archaeological bones too fragmentary to permit secure identification on morphological grounds. Backscattered electron (BSE) imaging is used to observe bone tissue types and the arrangement of vascular canals, and to facilitate quantification of osteonal canal dimensions. Examination of known examples of relevant taxa (humans [n = 8], pigs [n = 4] and dogs [n = 4]) shows significant differences among them. When the results of this examination are applied to a blind test of modern and archaeological specimens (humans [n = 8], pigs [n = 2]), 100% of specimens are identified correctly. The approach is applied to 13 morphologically unidentifiable fragments from Hawai’i and Fiji to evaluate its potential for identifying bone tools and to increase the number of samples available for dietary analysis. Potential applications of the approach for other contexts are discussed.     

Living and dying as subjects of the Inca Empire: Adult diet and health at Puruchuco-Huaquerones,Peru

Imperial strategies varied as the Inca expanded their empire from the capital in Cusco. Some communities were conquered violently while others were ruled indirectly with little evidence of Inca presence. According to ethnohistorical evidence, the central coast was peacefully annexed by the Incas ca. A.D. 1470, but little is known about how Inca imperialism may have affected the quality of life of subjects of the Inca Empire. We integrate multiple lines of evidence to assess diet, health and disease for a sample of human remains from the Late Horizon cemetery of Puruchuco-Huaquerones, Peru. Specifically, we examine and analyze osteological, dental and stable isotope data (n = 162, 90 and 46 respectively) in order to investigate whether the Inca period population at Puruchuco-Huaquerones experienced nutritionally insufficient diets and poor health under imperial policies. Diet at Puruchuco-Huaquerones incorporated a variety of foods, both plant and animal. Osteological lesions and stature indicate periods of stress, with males experiencing more illness relative to females. Stature sexual dimorphism, the presence of healed lesions and isotope data indicate a sufficiently nutritious diet and support the conclusion that, although disease was present, individuals were healthy enough to survive and recover. Geographical and temporal comparisons suggest that health changed little with the Inca annexation of this region, but future work is needed.     

Critical reassessment of putative Acheulean Porosphaera globularis beads

Excavations at Acheulean sites in northern Europe at the end of the 19th century have yielded fossil sponges belonging to the Late Cretaceous species Porosphaera globularis. The spherical morphology of these fossils, their small size, and the presence of a natural complete perforation in their center have led some archaeologists to interpret them as the oldest known beads. Others argue that the presence of these fossils at archaeological sites is due to natural processes. Re-examination of material collected during the 19th century has recently revived the bead interpretation. We tested the bead hypothesis by analyzing 13 samples of Porosphaera from nine sites in Britain and France. We conducted morphometric and microscopic analyses on specimens recovered from archaeological sites (n = 349), a natural geological sample, which was collected directly from Cretaceous strata (n = 352), and a sample from a Bronze Age burial (n = 43). Reappraisal of contextual data shows that the association of these finds with Acheulean artifacts is uncertain. Our results show that archaeological specimens are significantly different in size and perforation pattern from those of the natural geological sample. This may be due to size-sorting caused by sedimentary processes, size-selection by Palaeolithic people or by 19th century collectors. Modifications of the fossils' natural shape were detected on a few specimens in the form of localized abrasions and microchipping along the hole margins. A single specimen displays a facet close to the hole produced by grinding. The surfaces of these features exhibit a hue lighter than that observed on the remainder of the specimens indicating that they may be recent in origin and due to post-excavation and preservation treatment. However, this seems contradicted, for some specimens from Bedford, by the fact that according to Smith, W.G. [1884. On a Palaeolithic floor at North-East London. Journal of the Anthropological Institute of Great Britain and Ireland 13, 357–384] the specimens bearing microchipping and abrasions were found by him and “not touched or manipulated by the workmen”. We conclude that new excavations of these sites, involving systematic screening of sediments, are needed in order to attempt to solve the Porosphaera “mystery”.     

Osteoarthritis and body mass

Osteoarthritis is the second most common pathology found in anthropological collections. Although a great deal is known about osteoarthritis, it is not yet known whether in skeletal populations there is a correlation between osteoarthritis and body mass. In this study, lower limb and spinal osteoarthritis scores were taken to determine whether body mass and femoral length correlate with osteoarthritis on weight bearing joints. Osteoarthritis was measured using a four-point ordinal scale on a sample of 114 adult prehistoric Californian Amerinds. Body mass was calculated from femoral head breadth; femoral length was measured using standard procedures; and age and sex were determined through standard osteological procedures. Using Spearman correlations, body mass and femoral length did not correlate significantly with any of the osteoarthritis variables. Age correlated significantly with nearly all of the osteoarthritis variables (hip, r = 0.507; knee, r = 0.528; cervical, r = 0.513; thoracic, r = 0.647; lumbar, r = 0.507, P-values < 0.001); and body mass and femoral length correlated with sex (r-values = 0.835 and 0.654, P-values < 0.001). With age and sex controls, body mass negatively correlated with the hip osteoarthritis variable (r = −0.202, P < 0.05), but not with any of the other osteoarthritis variables. Results concur with previous findings in the anthropological literature and highlight complexities of osteoarthritis etiology.     

Statistical methods for bioarchaeology: applications of age-adjustment and logistic regression to comparisons of skeletal populations with differing age-structures

Previous studies of patterns of osteoarthritis involvement in prehistoric skeletal populations have been used to suggest differences in lifestyle or subsistence patterns. In spite of the intriguing nature of such studies, inadequate controls for the potential confounding effects of age have made results less secure than they appear. While researchers remain unable to control for the inherent limitations imposed by preservation bias, meaningful advancement could be made in the analysis of these data. Here we propose two methods from epidemiology that would allow more robust comparisons between populations with differing age-structures: age-adjustment and logistic regression. We apply these two methods to previously published data from prehistoric populations of the American Great Basin. In doing so, we are able to discern sex differences in risk for osteoarthritis at the shoulder (beta = −1.82, SE = 0.74, OR = 0.16, 95% CI = 0.04–0.69, p = 0.013), elbow (beta = −2.07, SE = 0.82, OR = 0.13, 95% CI = 0.03–0.63, p = 0.011), and in the foot (beta = −3.11, SE = 1.57, OR = 0.04, 95% CI = 0.00–0.97, p = 0.048), that were not noted in previous analyses of these data. These findings suggest that greater clarity of results and more precise comparisons of risk may be achieved by using these methods. We conclude that further application of these methods to bioarchaeological studies would potentially improve what can be said about prehistoric health patterns and lifeways.     

Morphological Characteristics of Healthy and Osteoarthritic Joint Surfaces in Archaeological Skeletons

Osteoarthritis is a major health concern in living populations, as well as being one of the most common pathological lesions identified in the archaeological record. The aetiology of the disease remains unclear, with a multi‐factorial influence of physical strain, age, genetics, and obesity. Previous studies have identified a relationship between the presence of knee osteoarthritis on the distal femoral joint and the morphology of the intercondylar notch, patellar groove, and medial condyle. The current study expands this research to investigate the relationship between distal femoral, distal humeral, and proximal ulnar joint morphology and osteoarthritis with 3D shape analysis techniques. These methods provide a more detailed analysis of joint morphology in order to determine any relationship between 3D shape and osteoarthritis. The results indicate a complex relationship between joint shape and knee osteoarthritis, with eburnated right femora showing a statistically significant association. The shapes associated with eburnated or affected femoral joints can be explained by osteophyte development, and therefore likely represent systematic shape changes and not a particular joint shape predisposing individuals to the condition. There was no identifiable relationship found in the proximal ulna or distal humerus, indicating that joint shape is unlikely to influence the development of the condition in the elbow joint and that any shape changes produced by osteoarthritis are not systematic or quantifiable. The joints analysed in this study were highly influenced by asymmetry, sexual dimorphism, and allometry, resulting in a small sample size of affected joints in many datasets. Further analyses of large skeletal samples are needed to more thoroughly investigate the possible relationship of distal femoral joint shape and osteoarthritis. Copyright © 2013 John Wiley & Sons, Ltd.     

The Still Bay points of Blombos Cave (South Africa)

We present the results of a technological and morphometric analysis of all the Still Bay points (n = 371) recovered from the 1993 to 2004 excavations at Blombos Cave. We have been able to reconstruct the manufacturing sequence of the bifacial points from initial shaping, by direct internal percussion, to finished morphology, by direct marginal percussion. Identifications of impact fractures and manufacturing breaks are based on comparisons with experimental and archaeological bifacial points of verified function, i.e. Paleoindian points from bison kill sites, replicates of Solutrean points mounted as spear-heads or arrowheads and shot into adult cattle, and experimental replication on local raw materials. Our analysis shows that: (a) only a minority of the points are finished forms, and that a large number of pieces are production failures, a situation known at bifacial point production sites of later ages; (b) morphometric and impact scar analyses should take into account this process and distinguish finished points from preforms and unfinished points; (c) there were at least three different kinds of raw material sources and that there is a marked increase in the frequencies of silcrete with respect to the M2 and M3 phases at Blombos; (d) three kinds of evidence prove that some of the points were hafted axially and used as spear tips; (e) production of bifacial points was a primary activity at the site but the hypothesis of intergroup exchange of Still Bay points cannot be sustained on the basis of present evidence; and (f) the Still Bay phase appears to initiate a trend to relatively rapid changes in specialized hunting weaponry and that this innovation is congruent with other innovations such as bone tools, shell beads and engraved ochre of the M1 and M2 phases at Blombos.     

Αge‐associated Variation and Sexual Dimorphism in Adult Cranial Morphology: Implications in Anthropological Studies

The current paper explores the impact of age and sex on adult cranial shape and size variation in the documented collections from St Bride's and Spitalfields. The scope is to assess the extent to which it is valid to pool age and sex groups in inter‐population comparisons that use cranial data. For this purpose, age and sex differences in cranial shape and size were explored using multivariate analysis of variance, Discriminant analysis and Mann–Whitney tests. The results suggest a clear change in cranial shape with increasing age; however, this change is not statistically significant. Therefore, it is justifiable to pool different age groups in bioarchaeological analyses. Increasing age also has a minimal impact on cranial size among females, whereas among males, its impact is small but statistically significant. Finally, cranial shape and size are significantly different between males and females, irrespective of their age. This dimorphism can be used for the assessment of sex, although attention should be given to over‐classification problems when using discriminant analysis. Copyright © 2012 John Wiley & Sons, Ltd.     

Why did the ancient inhabitants of Palmyra suffer fluorosis?

The skeletal remains uncovered from the 2nd and 3rd century underground tombs of Palmyra, Syria, retain traces of arthritis and mottled enamel. A brown discoloration was also observed in the teeth. In order to clarify that these facts can be related to fluorosis, the teeth excavated from Tomb C and F in the Southeast Necropolis were analyzed. The fluoride contents of the fluorosis-suspected teeth (0.56 ± 0.16% (n = 7)) were higher than those of normal teeth (0.16 ± 0.18% (n = 7)). The highest content (0.85%) proved that 22% of the hydroxide in apatite was substituted by fluoride. The fluoride concentrations of the natural water including deep well water available today in this area ranged from 0.3 to 3.0 mg l⁻¹. The highest fluoride concentration was found to be regulated by the dissolution equilibrium of fluorite, CaF₂, through the process of evaporation and concentration in this arid region. Because of the common ion effect by calcium ions in a high concentration, the fluoride concentration was lower than that expected from the solubility product of fluorite (8.2 mg l⁻¹). The mechanism of this process has probably remained unchanged since ancient times and therefore the drinking water used by the ancient people of Palmyra was estimated to contain fluoride at a level causing fluorosis.     

Quantitative computerized tomography for the diagnosis of osteopenia in prehistoric skeletal remains

In this study, we examine the value of bone density assessed by computed tomography (QCT) of the right tibia in the diagnosis of low bone mass in prehistoric bones. Trabecular bone mass (TBM) was assessed by histomorphometry in undecalcified bone sections of a small part of the proximal epiphysis of the right tibia of 78 prehispanic individuals. Bone density was also assessed in the proximal epiphysis of the right tibia, in an area of cancellous bone immediately adjacent to the wedge which was destined to histomorphometry, with the aid of a Tomoscan 60 TX™ (Philipps Medical System, Eindhoven, The Netherlands) using a phantom of hydroxyapatite included in plastic resin at three known concentrations (50, 100 and 200 mg/cc) and ethanol as fat equivalent. Bone density (as bone hydroxyapatite concentration in milligram per cubic centimeter) was calculated by means of a specific software tool (QCT Bone Mineral Analysis System, Image Analysis, California). We compared bone density assessed with QCT with TBM in these individuals, and also, with the results obtained from a modern control group. We calculated the median TBM of the prehispanic sample and tested the sensitivity, specificity, and overall accuracy of QCT in diagnosing TBM values below the median. We later performed the same analyses on 24 more prehispanic individuals. Both QCT (t = 5.61, p < 0.001) and TBM (t = 3.79, p < 0.001) were significantly lower among the prehispanic individuals than among the control ones. QCT showed a significant relationship with TBM (r = 0.41, p < 0.001). QCT values below 100 mg/cc serve to establish a diagnosis of low TBM values with a sensitivity of 82.1% and a specificity of 41%. In the test group sensitivity was 83.3% and specificity, 50%.     

Stable isotope palaeodietary study of humans and fauna from the multi-period (Iron Age,Viking and Late Medieval) site of Newark Bay,Orkney

We report here on stable carbon and nitrogen isotope measurements of human and faunal bone collagen from the Iron Age, Viking Age, and Late Medieval site of Newark Bay, Orkney, Scotland. We found a wide range of results for humans in both δ¹³C (−15.4‰ to −20.3‰) and δ¹⁵N (8.6‰–15.6‰) values. The enriched carbon and nitrogen values indicate the consumption of significant amounts of marine protein, which is very unusual for post-Mesolithic (e.g. 4000 cal BC) UK and European populations. Also of interest is a statistically significant difference in δ¹³C (t = −2.48, p = 0.011) and δ¹⁵N (t = −2.44, p = 0.011) values, and therefore diets, between adult males and females at this site, with males (δ¹³C = −17.8 ± 1.2‰, δ¹⁵N = 13.2 ± 1.6‰) having, on average, a higher proportion of marine protein than females (δ¹³C = −18.9 ± 1.1‰, δ¹⁵N = 11.8 ± 1.8‰). The weaning age of the sub-adults was difficult to interpret due to the large isotopic variation in the adult females, but nearly all individuals between birth and 1.25 years have elevated δ¹⁵N values indicating that they were breastfed to some extent.     

Modeling skeletal traits and functions of the upper body: Comparing archaeological and anthropological material

The aim of this study is to look at upper body functional modifications caused by mechanical loading. We look at 4th lumbar vertebra as well as fibrous humeral musculoskeletal stress markers (MSMs). This study uses information provided by magnetic resonance images of living individuals from the University of Oulu Hospital data banks (N = 91), archaeological skeletons from Sweden (N = 54) and England (N = 61), and autopsied skeletal collection of early 20th century Finns in Natural History Museum, University of Helsinki (N = 48). The lumbar vertebrae and MSM are subjected to mechanical loading caused by the upper body weight and loads lifted and/or carried. We hypothesized that the vertebral size reflect body size, habitual mechanical loading and the overall skeletal robusticity as mechanical competence to withstand mechanical loading standardized to body size, which has decreased over millennia. For Helsinki material occupation, age and sex is known and the material was used in Niinimäki (2011). In the study by Niinimäki (2011) MSM were found to be affected by the intensity of muscular action as well as body size and age. This study is reviewed here in light of re-analysis of the data to follow the current anatomical understanding of the entheses as well as viewing MSMs as a part of upper body functional complex. Only fibrous entheses were included in the re-analysis. Furthermore, due to small number of females where activity intensity could be assessed, females were dropped from the re-analysis.