Universal methodology for developing univariate sample-specific sex determination methods: an example using the epicondylar breadth of the humerus

In this paper we present a new methodology for developing sample-specific metric sex determination methods using unidentified individuals that can be applied to archaeological samples. This methodology does not require the assessment of sex of a large sample from pelvic morphological features as a first step in developing the method and instead is developed from a sample of individuals with sex unknown. The procedure involves using the overall mean of a measurement collected from the sample of unknowns as the discriminant criteria for determining the sex of the individuals in that same sample. Experiments with various sample sizes and sex ratios using distal humerus measurements from the Coimbra Collection (Portugal) suggest that allocation accuracies of 83–96% can be expected when the sample used to develop the method is greater than 40 individuals and the sex ratio is less than 1.5:1. The utility of the methodology is explored using the Lisbon Collection (Portugal) and an archaeological sample from Belleville (Canada) is tested as an example. The Lisbon Collection data indicate that joint measurements of long bones will provide the highest allocation accuracies. The results from the Belleville sample confirm that humerus joint measurements consistently provide the highest allocation accuracies (88–100%) even when the sex ratio in the sample used to develop the method is estimated at 1.9:1.     

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.     

Don't throw out the baby with the bathwater: Estimating fertility from subadult skeletons

Recent research interest has focused on the bioarchaeology of children. Although paleodemography is essential for accurate reconstructions of lifestyle and health in past populations, currently there is no published technique for estimating fertility and life expectancy at birth for skeletal populations in which adults are under‐enumerated. This paper provides a formula to predict Gross Reproductive Rate (GRR) from the proportion of young infants to subadults in a skeletal population. The formula was developed from 98 of Coale and Demeny's Female Model West Life Tables, which represented diverse fertility and mortality rates. The formula's accuracy was examined using independent samples from historical and archaeological cemeteries. Estimates of GRR from the subadult fertility formula were compared with estimates from Bocquet‐Appel and Masset's juvenile:adult ratio. Results indicate that the subadult fertility formula predicts GRR with consistent accuracy (R² = 0.98) and precision (± 1 offspring) in the model life tables, across diverse subadult age structures and demographic characteristics. The formula is useful for subadult populations with a proportion of perinates:subadults between 0.12 and 0.45. The adult component of the sample is not included in the analysis and thus the formula is similarly useful in cases where adults are under‐enumerated, or not. When applied to historical and archaeological populations, estimates for GRR are similar to previous estimates from the juvenile:adult ratio. Because crude birth rate and life expectancy at birth can be calculated from GRR using established fertility centred approaches to demography, the subadult fertility formula allows skeletal populations of diverse composition to be included in demographic research, essential for understanding of how mortality and fertility are affecting the morbidity profiles of subadult samples and for comparative bioarchaeological analyses. Copyright © 2010 John Wiley & Sons, Ltd.     

Sex estimation using cervical dental measurements in an archaeological population from Iran

Sex estimation of skeletal remains is one of the major components of forensic identification of unknown individuals. Teeth are a potential source of information on sex and are often recovered in archaeological or forensic contexts due to their post-mortem longevity. Currently, there is limited data on dental sexual dimorphism of archaeological populations from Iran. This paper represents the first study to provide a dental sex estimation method for Iron Age populations. The current study was conducted on the skeletal remains of 143 adults from two Iron Age populations in close temporal and geographic proximity in the Solduz Valley (West Azerbaijan Province of Iran). Mesiodistal and buccolingual cervical measurements of 1334 maxillary and mandibular teeth were used to investigate the degree of sexual dimorphism in permanent dentition and to assess their applicability in sex estimation. Data was analysed using discriminant function analysis (SPSS 23), and posterior probabilities were calculated for all produced formulae. The results showed that incisors and canines were the most sexually dimorphic teeth, providing percentages of correct sex classification between 86.4 and 100 % depending on the measurement used. The combination of canines and other teeth improved significantly the level of correct sex classification. The highest percentages of sex classification were obtained by the combination of canines and incisors (100 %) and canines and molars (92.3 %). The present study provided the first reference standards for sex estimation using odontometric data in an Iranian archaeological population. Cervical measurements were found to be of value for sex assessment, and the method presented here can be a useful tool for establishing accurate demographic data from skeletal remains of the Iron Age from Iran.     

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.     

Subadult Age at Death and Health Status at Niah Cave,Borneo (1500–200 bc)

Southeast Asia's transition to rice agriculture is often used as an exception to the general pattern of health decline at the agricultural transition. Niah Cave is the largest known Southeast Asian Neolithic cemetery, providing valuable information about subadult health during the agricultural transition in this region. This study examines the health status and mortuary treatment of subadult skeletal remains (Minimum Number of Individuals (MNI) = 49) from the Neolithic cemetery of Niah Cave, Sarawak, Malaysia (1500–200 bc ). This study found that few cases of cribra orbitalia (4.6%) and porotic hyperostosis (14%). However, nonspecific infections may have been a risk factor for subadults as over half (65%) died with active cases of periosteal reactions on their long bones. Differential diagnosis determined that possible factors for this include parasite load, rickets and scurvy. Mortuary practices indicate that subadults may have been treated differently in phases 1 and 2 but were grated similar mortuary treatment in phases 3 and 4. This study suggests that changes in mobility patterns may have placed subadults at risk for increased parasite load and vitamin deficiency, while the role of subadults within the community may have changed over time. Copyright © 2017 John Wiley & Sons, Ltd.     

Patterns of Cranial Trauma in a Prehistoric Population from Central California

Evidence of cranial trauma was investigated in a skeletal sample from the site CA-Ala-329 located on the eastern side of San Francisco Bay, Central California. The sample included 365 crania, including 134 adult males, 104 adult females, 22 adults of indeterminate sex and 105 subadults. Evidence of cranio-facial fracture was found in eight individuals, one of whom is an adolescent. Thus, the frequency in adult crania of traumatic injury is 7/260 (2.7 per cent). Of the seven individuals of known sex displaying such cranial trauma, all are male. The injuries are generally suggestive of some form of interpersonal aggression, with five healed vault fractures, one lesion with an embedded obsidian fragment (a probable projectile point) and two healed facial fractures. Further clear evidence of interpersonal aggression has been previously determined in this sample and has been reported at even higher levels elsewhere in California. © 1997 by John Wiley & Sons, Ltd.     

Age estimation of children from prehistoric Southeast Asia: are the dental formation methods used appropriate?

Inter-population differences in skeletal and dental growth and maturation are acknowledged frequently in the biological anthropological literature. These growth differences have implications for the reliability of standards for the estimation of age at death of archaeological subadults. The number of archaeological projects that are recovering human burials from non-European contexts, including Southeast Asia, and the increasing interest in subadult bioarchaeological studies provides the impetus for investigating this issue of ageing subadult individuals from these populations. This paper aims to address some of the problems of the representativeness of ageing standards for non-European children in bioarchaeology. This is achieved through a literature review of the issue of growth variability and age estimation, and a basic comparison of the commonly applied age estimation method based on North American children with a dental formation study of modern Thai children. Although these studies do not employ similar methods the Thai study is the only comparable data available and therefore serves as a starting point to address these issues. The results raise an important question for bioarchaeologists of the appropriateness of available ageing methods. In addition this paper emphasises the need for the use of appropriate methodologies in the collection and presentation of dental formation data.     

The demographic,socio‐economic and temporal contextualisation of the Universitat Autònoma de Barcelona collection of identified human skeletons (UAB collection)

Identified human skeletal collections are those in which basic demographic data (sex, age and biological origin) are known and are crucial for developing and testing osteological methodologies. It is important that the identified collection be contextualised, and in this way the collection will be considered a reference collection. To contextualise a collection requires documentation of the basic demographic data of the individuals (sex, age, year of birth, geographical area) as well as information concerning the socio‐economic and temporal context in which the individuals lived. The contextualisation of an identified collection is very important so the researchers can understand the ‘point of reference’ when applying a method to it or developing a new method. The purpose of this study is to contextualise the identified skeletal collection of the Universitat Autónoma de Barcelona (UAB) which currently contains 35 adult skeletons of both sexes. To carry out the objectives of the present study, the information about the individuals was collected from cemetery registers and compared with the information of the demographic and statistic public institutions of Spain. The results indicate that the UAB collection is formed only by Spanish nationals who mainly lived during the 20th century in Granollers (Barcelona, Spain). Both sexes are equally represented and all of the individuals are adults. They reflect the most current adult population structure of Catalonia and be treated as a Catalan reference sample of adults living in the 20th century. This collection offers special opportunities for demographic analysis, including validation studies of skeletal ageing and sexing methods that target adult individuals. The collection can also be used in conjunction with other reference samples to investigate secular and populational change in cranial form, sexual dimorphism and stature. Copyright © 2010 John Wiley & Sons, Ltd.     

Is the circumference at the nutrient foramen of the tibia of value to sex determination on human osteological collections? Testing a new method

This paper tests the validity of the circumference at the nutrient foramen of the tibia for sex determination on two human osteological collections: the Lisbon Collection of Identified Skeletons (n = 160) and the São Martinho medieval archaeological collection from Leiria, Portugal (n = 57). The methodological approach chosen to conduct the test was the sectioning point method. The overall accuracy (males and females combined) in the Lisbon Collection was 78% and in the São Martinho Collection it reached 90%. In both series, females were more accurately classified than males. This paper advocates the importance of developing and using sample specific methods for sex determination in modern and in archaeological human osteological assemblages. Copyright © 2010 John Wiley & Sons, Ltd.     

Sex identification from the auricular surface of the adult human ilium

The sacro-iliac joint has largely been excluded in studies of sex identification from the adult human skeleton. Yet this is a joint involved in the transmission of body weight and as such would be expected to exhibit sexual dimorphism. In addition, the auricular surface of the ilium tends to persist even in fragmented remains by virtue of its close proximity to the acetabulo-cristal buttress. The aim of this investigation was to assess the accuracy with which sex could be predicted from dimensions of the auricular surface of the ilium. Significant sex differences were found in the size and shape of the auricular surface. However, these differences were of insufficient magnitude to permit discrimination between the sexes with any acceptable degree of accuracy. Therefore, the auricular surface of the ilium is not recommended for the purpose of sex identification.     

Subadult Age‐at‐Death Estimation From the Human Calcaneus

The estimation of age from subadult skeletal remains relies on the measurement of bones, which when unavailable or damaged hampers the ability to generate a reliable age estimate. The goal of this project was to demonstrate two methods for estimating age at death from the developing human calcaneus. These methods are generated from a sample of 32 European American and African American males and females with ages ranging from 1 to 19 years from the Hamann–Todd Collection. The first method was based on linear regression from two standard measurements of the calcaneus (maximum length and middle breadth); the second was based on transition analysis of fusion states of the calcaneal epiphysis. Results suggest that both methods perform well in estimating subadult age at death. Additional testing with larger contemporary samples would likely increase the accuracy of both methods. Copyright © 2011 John Wiley & Sons, Ltd.     

Consequences of conquest? The analysis and interpretation of subadult trauma at Puruchuco-Huaquerones, Peru

This paper examines bioarchaeological evidence of violence and traumatic injury on subadult skeletal remains from two Late Horizon (A.D. 1470-1540) cemeteries within the archaeological zone of Puruchuco-Huaquerones, Peru. Here we present the frequency and types of traumatic lesions on the 242 subadults analyzed. We observed significant increases in the frequency of subadult trauma, particularly among the burials associated with Spanish Conquest. Specifically, we noted a statistically significant increase in the frequency of cranial trauma in a subsample of individuals from one of two cemeteries at the site, 57AS03. These perimortem cranial injuries suggest an intensification of violence and lethality that may have affected the children from this community. We then discuss the biocultural implications of this analysis within the context of Spanish invasion and conquest.     

Interpreting diachronic osteological variation at the medieval necropolis of the Sant Pere Churches (Terrassa,Spain)

The purpose of this study is to analyse the diachronic variation in the skeletal sample exhumed from the medieval necropolis of Sant Pere Churches, interpreting the results using the archaeological and historical evidence. The Sant Pere Churches are a monumental Romanic complex located in Terrassa (Spain) and built over the earlier Episcopal Cathedral of Egara from the Visigoth period. Egara has traditionally been considered the precursor of the current city of Terrassa; however this name disappeared from historical documentary sources after the period of Muslim incursions into Hispania (8th century). An archaeological excavation undertaken recently at the Sant Pere Churches provided us with the opportunity to study the population that was interred in this complex during that epoch. In total, the skeletal remains of 208 individuals were examined. In order to analyse the diachronic variation, the sample was divided into two periods, that of the Cathedral of Egara (4th–8th centuries; N = 128) and that of the Parish Churches of Terrassa (9th–13th centuries; N = 80). Both periods of the complex exhibited a similar skeletal age distribution, including under‐representation of non‐adult individuals. Nevertheless, a bias towards males in terms of sex distribution, sex differences in the mortality level and greater sexual dimorphism were observed in the population interred at the Cathedral of Egara. Moreover, analysis of the prevalence of skeletal disorders also provided evidence of higher differences between sexes for the period of the Episcopal Cathedral of Egara, the female population exhibiting the lower prevalence. Additionally, diachronic variation in both postcranial and dental disease patterns was observed, suggesting different activity patterns and food consumption between the periods. Overall, the results suggested that diachronic osteological variation observed in the Sant Pere Churches skeletal sample was most probably linked with the changes in the role of the complex following the Muslim incursion of the 8th century. Copyright © 2009 John Wiley & Sons, Ltd.     

Investigating foetal and perinatal mortality in prehistoric skeletal samples: a case study from a 3000-year-old Pacific Island cemetery site

The Teouma skeletal sample from Vanuatu represents one of the few truly colonising populations in the Pacific Islands. Therefore, investigating the factors that may have affected foetal/infant mortality in this population is potentially important for understanding the success of settlement in this region of the world. We investigate whether stable isotope analyses of carbon and nitrogen in conjunction with skeletal ageing techniques, can aid in identifying whether the subadults from Teouma died before or after birth in an attempt to understand the potential threats to foetal and infant survival. Multiple skeletal ageing methods using diaphyseal lengths were used to age the young subadults (n = 7). Using regression-based skeletal ageing methods, four of the individuals were aged at around full-term gestation (37–42 weeks gestation), while the remaining three individuals died preterm. The isotope analyses did not assist in identifying the individuals that survived post-birth because none of the subadults displayed the 2–3‰ trophic increase in δ¹⁵N values expected for a breastfed infant, probably as a result of their young age. However, all of the foetal/perinatal individuals exhibited higher δ¹⁵N values in their bone collagen compared with the adult females of the sample, with two of the individuals demonstrating unusually high δ¹⁵N values. The δ¹³C values of the foetuses/perinates did not exhibit the same variation. We explore a number of possible explanations for this elevation of perinatal/foetal δ¹⁵N values and tentatively suggest that this is a result of in utero stress as a consequence of chronic maternal ill-health. The osteological and palaeodemographic evidence supports the assertion that females, foetuses and perinates were susceptible to environmental stress within this colonising population, resulting in early death of the perinatal individuals in addition to early terminations of pregnancy or premature birth possibly caused by infectious and/or metabolic diseases.     

Mandibular ramus posterior flexure: a sex indicator in Homo sapiens fossil hominids?

Accurate determination of sex in skeletal human samples is very important in anthropological and demographic studies. Recently, Loth and Henneberg have suggested that a new osteological criterion on the mandible, the mandibular ramus posterior flexure (MRPF) had a high sex discriminating effectiveness. A preliminary test applied to a few hominid mandibles )including Australopithecines, Homo erectus, Neanderthals and Upper palaeolithic hominids) apparently confirmed the high reliability of the MRPF as a sex indicator ‘over time and through palaeospecies’. As the pelvis is commonly considered as providing the most significant criteria that allows the establishment of skeletal sexual dimorphism of adults, the present paper evaluates this mandibular feature on a few additional palaeolithic hominids (i.e. Neanderthals and Early Modern Humans) for whom a gender estimation was known based upon the pelvis. This analysis was conducted on the original material and its results appear in contradiction with those of the previous studies made by Loth and Henneberg. A reconsideration of the visual assessment of MRPF as a sex indicator in Homo sapiens fossil hominids is therefore suggested. Copyright © 2000 John Wiley & Sons, Ltd.     

A regional investigation of subadult dietary patterns and health in late Iron Age and Roman Dorset,England

This is the first regional analysis of the impact of Romanisation on subadult dietary patterns and related health parameters in Britain. A sample of 200 subadults from late Iron Age (LIA) and Romano-British (RB) Dorset were examined for dental health and specific metabolic diseases, and a sub-sample of 29 individuals were selected for nitrogen and carbon isotope analysis. The results showed that dental health declined in the Romano-British period and the incidence of scurvy and rickets rose. Increased consumption of marine foods in the RB period is indicated by an increase in δ¹³C between the LIA and RB subadults. After early childhood, there was no age-dependent variation in dietary protein in the RB and LIA populations from Dorset. We propose that these changes related to the introduction of urban living, Romanised diets and population migration.     

The effect of population variation on the accuracy of sex estimates derived from basal occipital discriminant functions

Multiple discriminant functions that estimate sex from the dimensions of the basal occipital have been published. However, as there is limited exploration of basal dimension variation between groups, the accuracy of these functions when applied to archaeological material is unknown. This study compares basal dimensions between four known sex-at-death post-medieval European samples and explores how metric differences impact on the accuracy of sex assessment discriminant functions. Published data from St Bride’s, London (n = 146) and the Georges Olivier collection, Paris (n = 68) were compared with new data from the eighteenth to nineteenth century Dutch Middenbeemster sample (n = 74) and the early twentieth century Rainer sample, Romania (n = 282) using independent t tests. The Middenbeemster and Rainer data were substituted into six published discriminant functions derived from the St Bride’s and the Georges Olivier samples, and the results were compared to their known sex. Multiple statistically significant differences were found between the four groups. Of the six discriminant functions tested, five failed to reach the published accuracy and fell below chance. In addition, even where the samples were statistically comparable in means, trends for difference also impacted the accuracy of discriminant functions. Enough variation in basal occipital dimensions existed in the European groups to decrease the accuracy of sex estimation discriminant functions to unusable. Possible inter-observer error, varying genetic, socioeconomic, and geographical factors are likely causes of dimension variation. This research further highlights the dangers of using sex estimation discriminant functions on samples that differ to the original derivative population and demonstrates the need for more rigorous testing.