Pugacheva Ekaterina Vladimirovna

Introduction. There are several standardized methods for estimating the age of a skull. Most of these methods are based on the analysis of suture obliteration and the tooth wear scoring. However, many anthropologists prefer a more subjective approach, relying on general impressions without using a set of standardized criteria. This study aimed to assess the effectiveness of a visual method for age estimation and reconstruction of age-at-death structure in a skeletal sample.

Materials and methods. The study was based on a series of 116 skulls from the early 20th century collected by the Peter the Great Museum of Anthropology and Ethnography (Kunstkamera). These specimens had documented sex and age information. Two researchers independently assessed the age of the skull specimens and recorded the degree of suture fusion on the cranial vault as well as the level of tooth wear on the occlusal surfaces. The correlation between age and estimated scores was calculated using Spearman’s rank correlation coefficient. The discrepancy between estimated and actual ages was measured by calculating the mean absolute error (MAE) and systematic error (SE) as the average difference between documented and estimated ages for the entire sample as well as for each age group. Intraclass correlation coefficients were used to assess the consistency of the authors’ estimates.

Results. The authors' estimates showed moderately high agreement among themselves and a moderate positive correlation with actual age. The accuracy of the visual assessments was found to be comparable with that of more formalized methods for assessing the degree of suture obliteration. The estimates also exhibited the phenomenon of regression to the mean, with individuals in younger cohorts being systematically overestimated in terms of age and those in older cohorts being underestimated. The accuracy of determining the age-at-death distribution depends to some extent on the actual characteristics of the sample structure. Averaging estimates from different authors or several estimates from the same author, repeated over a large time interval, makes it possible to bring estimates closer to real data.

Conclusion. Increasing interobserver agreement of age estimates can be achieved by fixing traits on the same point scales, as well as by increasing age intervals. The accuracy of estimates can be improved by repeated age estimation as well as the “wisdom of the crowd” effect. © 2024. This work is licensed under a CC BY 4.0 license

Introduction. Skulls from the medieval necropolis Shulluktepa (Nesef, XI-XII centuries) were previously studied using 2D geometric morphometrics. Based on the analysis of the sagittal contour, two types of artificial cranial deformation were identified. These types could be associated with different populations gathering in this urban center of Southern Sogdiana. We observed that samples with different types of deformation could be clearly distinguished, while undeformed skulls differ from slightly deformed insignificantly. 3D models and the landmark’s placement algorithm we have developed allow us to utilize these materials again.

Materials and methods. 3D models of skulls from Shulluktepa (MAE No. 7275) were studied using geometric morphometrics. The sample included 44 male and 42 female skulls. The types of deformation were analyzed through processing the landmark’s coordinates within a triangular patch between craniometric points (bregma, left and right asterions). The surface of this patch was automatically filled with semilandmarks. The comparison was carried out using generalized Procrustes analysis, Principal component analysis and canonical analysis realized in R-Studio.

Results and discussion. Based on the analysis results artificially deformed skulls were divided into two types of cranial deformation — parietal and occipital. 3D methods, unlike 2D, allowed us to identify undeformed skulls. There are no differences between males and females in case of parietal deformation, but occipital deformation is more pronounced in males. Comparison of the viscerocranium and neurocranium variability confirmed their independence. There is no influence of interpopulation differences on the results of the neurocrania shape study.

Conclusion. The presence of two types of artificial cranial deformation in the group was proved. It was shown that a triangular patch is more advantageous for the study of artificial deformation than analysis of 2D sagittal contours. Results of the comparison of viscerocranium and neurocranium variability can be used to verify the possible influence of interpopulation differences.

Funding. The research was carried out with the support of grant Russian Scientific Found No. 25-28-01027 "Artificial deformation of the human skull in ancient and near-modern populations: a study by methods of two-dimensional and three- dimensional geometric morphometry”.