New Approach Towards the Problem of Somatic Criteria of Secular Trends. Sexual Somatic Dimorphism

Abstract

Introduction. The goal of study is description of secular dynamics of sex dimorphism (SD) of height, weight, chest girth of children aged 9 years and teenagers 13 years old from Russia and neighboring countries through 1920–2010. Materials and methods. The main source of data — materials of books on physical development of children and adolescents from cities and rural regions of Russia and USSR, collected and processed according to the universal methodical standards of Research Institute of Hygiene of children and adolescents. The quantitative estimation of SD value was held using Kullback divergence. One-year age groups, contrastive in biological essence, are under discussion. The estimation of the vector and level of associations of SD of anthropometric traits and secular factor was held using correlation analysis. The analysis of local patterns of secular SD dynamics of separate traits was carried out. Results. Secular variability of height and weight SD of 9-year-old children is not significant. While secular dynamics of three body dimensions of 13-year-old teenagers is significant, the highest determination coefficient is fixed for weight. For Moscow samples the decrease of height and weight SD is fixed through the historic interval 1960s – 70s with the following recovery up to the level of 1920s in 2000s. Temporal dynamics of SD of 9-year-old children of St. Petersburg through the interval 1960s – 2000s consists of macrosomization of girls; the tendency for 13-year-old teenagers is opposite. Temporal dynamics of somatic SD of 9-year-old Russian children of Kazan reveals stability through the interval 1960th-1990th; for 13-year-old teenagers’ parameters of transversal body development demonstrate secular stability, as to height – boys compensate their lag compared to girls. For Kirovsk city (Murmansk region) through the interval 1950s – 1970s temporal fluctuations of height and weight SD of 9-year-old children are less than 0,2 standard deviations; height and weight SD of 13-year-old teenagers reveal temporal increase (0,4–0,6 standard deviations). Conclusion. The results confirm the importance of somatic SD as the criterion of secular dynamics for 13-year-old teenagers and witness, as a whole, to the temporal stability of SD during second childhood (9 years). Local differences do not contribute significantly to the intensity of secular dynamics of SD. The process of secular macrosomization of one sex as compared to the other is not the exclusive prerogative of boys and male teenagers.