Validation of age estimation methods through the scapula in a Mediterranean non-adult population.

Age estimation methods through the metric study of bones in non-adult individuals are a frequently used tool in Biological and Forensic Anthropology; however, few methodological validation studies are available, given the limited number of adequate samples for their study. In this context, the aim of this work is to test the effectiveness of the methods of Fazekas and Kósa (1978), Saunders et al. (1993), Rissech and Black (2007) and Cardoso et al. (2017), for age estimation through the measurements of the scapula, in the non-adult osteological collection of the Anthropology Laboratory of the University of Granada (Spain), one of the most representative identified non-adult collections internationally. For this purpose, nine different measurements of the scapula were taken from a total of 149 non-adult individuals, applying the regression formulae proposed by the different authors and verifying their accuracy. Results have shown the existence of significant differences between the real age and the estimated age in almost all the tested methods, with degrees of error that differ from those obtained in the original study populations. Based on the obtained results, it is recommended to use the method of Cardoso et al. in postnatal individuals, always adjusting the degrees of error with those obtained in this work.

Age estimation in infant and prenatal individuals through the metric development of the pars petrosa and squamosal portion of the temporal bone.

This study proposes an assessment of the accuracy of the Fazekas and Kósa and Nagaoka methods by measuring the squamosal and petrous portions of the temporal bone, whose application in the Mediterranean population is not recommended. Therefore, our proposal is a new formula to estimate the age of skeletal remains from individuals at 5 months gestational age to 1.5 postnatal years with the temporal bone. The proposed equation was calculated on a Mediterranean sample identified from the cemetery of San José, Granada (n = 109). The mathematical model used is the exponential regression of the estimated age for each measure and sex, and both in combination, using an inverse calibration and cross-validation model. In addition, the estimation errors and the percentage of individuals within a 95% confidence interval were calculated. The lateral development of the skull, especially the growth of the length of the petrous portion, showed the greatest accuracy, while its counterpart, the width of the pars petrosa, showed the lowest accuracy, so its use is discouraged. The positive results from this paper should be useful in both forensic and bioarchaeological contexts.

Validation of discriminant functions from the rib necks in two Portuguese adult identified populations.

Sexual dimorphism is the basis for sex estimation research in skeletal remains, helping the positive identification of individuals in forensic backgrounds. In this regard, it has been proved that the metrical analysis of the costal neck of the first four ribs in Spanish contemporary adult skeletons shows high sexual dimorphism, especially in the first rib. However, the validation of any method developed in identified skeletal collections must be compulsorily reproduced in other skeletonized sets to verify either its potential application in individuals from other locations, or the existence of possible biases associated with inter-population variation. Due to the geographical and socioeconomic proximity between Spain and Portugal, this paper aims to check the utility of the discriminant functions designed by Partido-Navadijo et al. (2021) in the two skeletal collections of the University of Coimbra (Portugal). Results show the utility of these discriminant functions in Portuguese population, with frequencies of cases correctly assigned reaching up to 93.6% in the Coimbra Identified Skeletal Collection (CISC); and up to 92.6% in the 21st Century Identified Skeletal Collection (CEI/XXI). However, two particularities between the Spanish and Portuguese osteological assemblages can be highlighted: the possible existence of secular changes in relation to the CISC collection (1904-1938); and a reversal in the degree of costal dimorphism, being the third and fourth ribs of the CEI/XXI collection more dimorphic than the first ones.

Utility of the sternal synostosis for age-at-death estimation in a Mediterranean population.

Age estimation is essential for the identification of skeletal remains in Forensic Anthropology. Numerous studies have been performed on diverse regions of the skeleton, including the synostosis of the sternal segments. In this sense, the fusion of the different sternal segments was assessed to analyze whether it had a correlation with age-at-death in a Mediterranean population. A total of 189 sternums which belonged to individuals between the ages of 20 and 98 from both sexes (56.6% males; 43.4% females), from the San José's Cemetery of Granada Contemporary Collection (Spain), were selected. Scores ranging from 1 to 3 were assigned in accordance with the degree of manubrio-sternal fusion and sterno-xyphoidal fusion. Cohen's kappa coefficient for intra- and inter-observer error was performed and then chi-square test was run to analyze any correlation between the stage of synostosis and the skeletal age. Only the sterno-xyphoidal fusion, which starts between 30 and 39 years old, provided a predictable result, as the manubrium and the sternal body usually remain without fusion. This study demonstrates a direct correlation between fusion of the xyphoid process and chronological age.

Discriminant functions for sex estimation using the rib necks in a Spanish population.

One of the first steps in the identification of human remains is sex estimation. Discriminant functions are very useful for this purpose, as they are based on the fundamental premise of the sexual dimorphism in osseous remains. However, the absence of studies of this kind in the thoracic cage is visible, and adequate cause to justify this work. To this purpose, we analysed and measured a set of ribs, R1 to R4, belonging to skeletons of contemporary chronology (1970-2010), in order to obtain discriminant functions enabling sex estimation through equations applied to the rib neck. The sample comes from the Cemetery of San José, which is located at the Laboratory of Anthropology at the University of Granada. All data from this sample was known: ancestry, sex, age-at-death and cause of death. Results showed a percentage of success of approximately 80-88% in ribs R2 to R4, and approximately 85-90% in R1, reaching up to 93.2%. Results from intra-/inter-observer error tests show excellent reproducibility of the method. The data confirms that it is possible to estimate sex from the rib neck.