Assumpció Malgosa

Using the Acetabulum to Estimate Age at Death of Adult Males

ABSTRACT: The acetabular region is often present and adequately preserved in adult human skeletal remains. Close morphological examination of the 242 left male os coxae from the identified collection of Coimbra (Portugal) has enabled the recognition of seven variables that can be used to estimate age at death. This paper describes these variables and argues their appropriateness by analyzing the correlation between these criteria and the age, the intra‐ and interobserver consistence, and the accuracy in age prediction using Bayesian inference to estimate age of identified specimens. Results show significant close correlation between the acetabular criteria and age, nonsignificant differences in intra‐ and interobserver test, and 89% accuracy in Bayes prediction. Obtained estimated age of the specimens had similar accuracy in all ages. These results indicate that these seven variables, based on the acetabular area, are potentially useful to estimate age at death for adult specimens.

Sex assessment on the basis of long bone circumference

Discriminant functions have long been used to classify individuals into groups according to the dimensions of their bones. Although lengths, widths, and diameters have been extensively used, the circumferences have not been adequately validated. In this work, the importance that the circumferences of long bones can have in assigning the sex of ancient human remains is demonstrated. The functions produced by using just one circumference achieved accuracies higher than 80%, and circumference at the radial tuberosity of the radius is able to classify 92.8% of skeletons from the Late Roman site of Mas Rimbau/Mas Mallol (Spain). When functions are produced by using more than one circumference, they can achieve the uppermost classification attained in this sample. The functions also showed that the arm circumference functions are more useful than those of the leg, probably because male individuals of the population had greater mechanical stress than did females. The classification percentages, as well as other statistical values for the functions, demonstrated the great ability of long bone circumferences in helping to classify the sex of individuals of other sites of the Mediterranean area besides the ones examined in this study.

Sex and age diagnosis by ischium morphometric analysis

The growth of four variables of the ischium was analysed by polynomial regression in order to evaluate its significance and its capacity for age and sex determination during and after growth. The material used was 327 specimens ranging from birth to 97 years of age from four documented west European collections. The growth curves were calculated for ischium length and three new variables of the acetabular surface (horizontal diameter of ischium acetabular surface, vertical diameter of ischium acetabular surface and ischium acetabular index). All curves, except those of the female series of vertical diameter of ischium acetabular surface and its index, showed a lineal growth corresponding to vertical variables. All variables studied, except the ischium acetabular index, can be used variables for adult sexual discrimination. Furthermore, ischium length and the horizontal and vertical diameters of the acetabular surface can be useful for sub-adult age determination in archaeological samples, as well as in forensic samples. However, the ischium length is the best variable, as it can be applied to all the growth ages.

Estimation of Age-at-Death for Adult Males Using the Acetabulum, Applied to Four Western European Populations*

Abstract:  Methods to estimate adult age from observations of skeletal elements are not very accurate and motivate the development of better methods. In this article, we test recently published method based on the acetabulum and Bayesian inference, developed using Coimbra collection (Portugal). In this study, to evaluate its utility in other populations, this methodology was applied to 394 specimens from four different documented Western European collections. Four strategies of analysis to estimate age were outlined: (a) each series separately; (b) on Lisbon collection, taken as a reference Coimbra collection; (c) on Barcelona collection, taken as a reference both Portuguese collections; and (d) on London collection taken as reference the three Iberian collections combined. Results indicate that estimates are accurate (83–100%). As might be expected, the least accurate estimates were obtained when the most distant collection was used as a reference. Observations of the fused acetabulum can be used to make accurate estimates of age for adults of any age, with less accurate estimates when a more distant reference collection is used.

The Potential of X‐Ray Diffraction in the Analysis of Burned Remains from Forensic Contexts

Abstract:  In view of the difficulties in extracting quantitative information from burned bone, we suggest a new and accurate method of determining the temperature and duration of burning of human remains in forensic contexts. Application of the powder X‐ray diffraction approach to a sample of human bone and teeth allowed their microstructural behavior, as a function of temperature (200–1000°C) and duration of burning (0, 18, 36, and 60 min), to be predicted. The experimental results from the 57 human bone sections and 12 molar teeth determined that the growth of hydroxylapatite crystallites is a direct and predictable function of the applied temperature, which follows a nonlinear logistic relationship. This will allow the forensic investigator to acquire useful information about the equilibrium temperature brought about by the burning process and to suggest a reasonable duration of fire exposure.

Development of the femur—Implications for age and sex determination

Growth of four variables of the femur (diapyseal length, diaphyseal length plus distal epiphysis, maximum length and vertical diameter of the head) was analyzed by polynomial regression for the purpose of evaluating its significance and capacity for age and sex determination throughout the entire life continuum. Materials included in analysis consisted of 346 specimens ranging from birth to 97 years of age from five documented osteological collections of Western European descent. Linear growth was displayed by each of the four variables. Significant sexual dimorphism was identified in two of the femoral measurements, including maximum length and vertical diameter of the head, from age 15 onward. These results indicate that the two variables may be of use in the determination of sex in sex determination from that age onward. Strong correlation coefficients were identified between femoral size and age for each of the four metric variables. These results indicate that any of the femoral measurements is likely to serve as a useful source to estimate sub-adult age in both archaeological and forensic samples.

Authenticating ancient human mitochondrial DNA.

The use of ancient DNA techniques in human studies has been hampered by problems of contamination with modern human DNA. The main problem has been that the object of study belongs to the same species as the observer, and the complete elimination of the contamination risk is seemingly unlikely. Contamination has even been detected in the most specialized laboratories in this field. In these kinds of studies it is therefore very important to detect contamination and to distinguish contaminants from authentic results. Here, we report the use of a strategy to authenticate the identity of ancient mitochondrial DNA (mtDNA), based on the previously established relationship between D-loop sequence substitutions and haplogroup-specific restriction site changes. Forty-four individuals from a 16th-century necropolis were analyzed, from which 28 control region sequences were obtained. These sequences were preclassified into haplogroups, according to the observed motifs. Subsequently, the DNA extracts from which the sequences were obtained, along with independent extracts of subsets of the same individuals, were subjected to restriction fragment length polymorphism (RFLP) analysis to compare and corroborate the results. Using this approach, 24 sequences were authenticated, while two were discarded because of result mismatches. The final distribution of the haplogroups in the sample, and the differences in the sequences, are two additional criteria of authentication.

The acetabular point: a morphological and ontogenetic study

The acetabular point was analysed by studying human pelvic bones from 326 individuals ranging from newborns to age 97 y. The bones were categorised into 3 groups according to the degree of fusion for the 3 elements of the pelvis: nonfused (59), semifused (5) and fused (262). The acetabular point in immature pelvic bones is clearly represented by the point of the fusion lines for each bony element at the level of the acetabular fossa. In adult pelvic bones the acetabular fossa has an irregular clover‐leaf shape, the superior lobe being smaller than the anterior and posterior lobes. Cross‐sectional analysis of acetabular morphology suggested that the acetabular point in adult pelvic bones is always represented by the indentation between the superior and the anterior lobes of the acetabular fossa.

Determination of Human Caucasian Mitochondrial DNA Haplogroups by Means of a Hierarchical Approach

In this paper we propose a hierarchical approach that allows the screening of mitochondrial DNA (mtDNA) haplogroups in populations that have essentially West Eurasian mtDNA backgrounds but that could have some non-West Eurasian contributions. To develop and validate this scheme, we used data on 18 coding region polymorphisms (17 analyzed by RFLP analysis and 1 by sequencing) and sequences of hypervariable segment I (HVSI) of the mtDNA control region from the Azores Islands (Portugal) population. The proposed scheme allows the characterization of almost all West Eurasian and African major clusters by means of RFLPs. Furthermore, the scheme includes information on situations in which sequencing is pertinent to defining a particular haplogroup. The validity of the scheme is ensured by (1) using relatively stable polymorphic positions, (2) screening more than one position to define a specific haplogroup, and (3) typing confirmatory positions. Dubious samples can be resolved by sequencing. The robustness of this approach was assessed by sequencing all samples for HVSI, taking advantage of the previously established relationships between RFLPs and control region sequence polymorphisms. The use of this hierarchical approach avoids the screening of unnecessary control region polymorphisms and therefore results in a more rapid and cost-efficient screening than one in which all polymorphic positions are analyzed. Even if this approach leads to a lower level of phylogeographic resolution than the sequencing of all samples, it allows us to define population movements on a continental level and can be applied, unlike sequencing all samples, with a low cost in any laboratory. [End Page 431]

Tracing the Origin of the East-West Population Admixture in the Altai Region (Central Asia)

A recent discovery of Iron Age burials (Pazyryk culture) in the Altai Mountains of Mongolia may shed light on the mode and tempo of the generation of the current genetic east-west population admixture in Central Asia. Studies on ancient mitochondrial DNA of this region suggest that the Altai Mountains played the role of a geographical barrier between West and East Eurasian lineages until the beginning of the Iron Age. After the 7th century BC, coinciding with Scythian expansion across the Eurasian steppes, a gradual influx of East Eurasian sequences in Western steppes is detected. However, the underlying events behind the genetic admixture in Altai during the Iron Age are still unresolved: 1) whether it was a result of migratory events (eastward firstly, westward secondly), or 2) whether it was a result of a local demographic expansion in a ‘contact zone’ between European and East Asian people. In the present work, we analyzed the mitochondrial DNA lineages in human remains from Bronze and Iron Age burials of Mongolian Altai. Here we present support to the hypothesis that the gene pool of Iron Age inhabitants of Mongolian Altai was similar to that of western Iron Age Altaians (Russia and Kazakhstan). Thus, this people not only shared the same culture (Pazyryk), but also shared the same genetic east-west population admixture. In turn, Pazyryks appear to have a similar gene pool that current Altaians. Our results further show that Iron Age Altaians displayed mitochondrial lineages already present around Altai region before the Iron Age. This would provide support for a demographic expansion of local people of Altai instead of westward or eastward migratory events, as the demographic event behind the high population genetic admixture and diversity in Central Asia.