On some methodical aspects of estimation of intergroup morphological variability in growth studies

The significance of growth activity peak in screening studies of children and adolescents as biomarker of chronobiological status of the population is the focus of present research. The broad spectrum of samples (N = 43), including different ethnoterritorial groups of Russia and former USSR, examined throughout a wide historical period of second half of 20th — beginning of 21st century, was included in the analysis. The material source was data from literature and authors’ own databases. The following indicators of growth activity peak were calculated for each group: age (in years) of the maximal velocity of growth changes of the average level of height through the adolescence, estimated by empiric rows of annual changes of mean height with further smoothing by the least squares method — separately for boys and girls; its absolute value (cm) and chronological age (years). Intragroup sexual differences of these characteristics were considered as well. The subsequent statistical analysis (Statistica 10 package was used) revealed, that intergroup distribution of age at peak height velocity was not Gaussian and gravitated towards bimodality for both sexes. Herewith the least urbanized groups (rural Abkhazians and urban Mongolians) were excluded from analysis due to the specificity of the dynamic lines of height gains. The factor analysis established autonomy of pubertal growth acceleration of male and female teenagers — the first factor describes growth activity for males, the second one — for females. The analysis of intergeneration dynamics of age at peak height velocity, on the example of Moscow boys and girls, established, that the used parameter might indicate occasional changes of quality of life of a population (for example, introduction of free school lunches during the NEP period), as well as more global changes (intensified urbanization throughout the 20th century). The results of the study suggest that the variability of the growth activity peak parameters indicate significant social/anthropogenic base of chronobiological status of the population and independent growth strategies of males and females, which allows considering it as valid and promising biomarker in population growth studies.