Age and sex variability of measuring features of the head and face in the adult Khalkha population of Mongolia

Abstract

Introduction. A number of studies have shown that the Khalka rural pastoral population of Mongolia leading a traditional lifestyle is not characterized by acceleration of development and a secular trend in somatic characteristics of the body. The purpose is to study the morphological variability of head and face features in the adult rural Khalkha-Mongolian population against the background of variability of the same features in the Chuvash group and try to catch acceleration trends based on measuring head features. Materials and methods. The data (370 men and 355 women aged 18-60) was obtained during anthropoecological expeditions in 1986-1990 in 4 Khalkha-Mongolian somons. As a comparative material, data on the Chuvash of Bashkiria were used. Regression analysis was applied. The age-related variability of normalized values of cephalometric traits was assessed using variance analysis. For the Mongolian and Chuvash populations, the coefficients of sexual dimorphism of individual features of the face and head (according to V. Deryabin`s formula), as well as the Mahalanobis distance between female and male samples were determined. Results and discussion. For the studied characteristics (head length and breadth, the minimal forehead breadth and facial breadth, face height, facial and head indexes) in men, no reliable links were found between the variability of these traits and age. Variance analysis of normalized values of cephalometric signs revealed no differences in either the male or female Mongolian sample. The Mahalanobis distances calculated from the complex of head and face signs between the female and male Mongolian subsamples are noticeably smaller than the corresponding values obtained for the Chuvash group. Conclusion. Comparative studies of the age dynamics of a number of measuring features of the head for about one and a half generations of the twentieth century in Khalkha-Mongols (adapted groups) and Chuvash (populations with impaired adaptation due to changes in socio-economic environmental factors) showed weakly pronounced morphological changes in the features on the head and face in the studied population groups. There were no significant age differences in the complex of features of the face and head in the Khalkhas populations. Data on sexual dimorphism of facial and head features in Mongols and Chuvash have been introduced into scholarly discourse, and in the Mongolian population the values of indicators of sexual dimorphism of cephalometric signs are less than in Chuvash sample. @ 2023. This work is licensed under a CC BY 4.0 license