Изменчивость полового диморфизма основных соматических показателей новорожденных в связи с секулярным фактором (по материалам РФ и бывшего СССР на временном интервале с начала XX – до начала XXI века)

Abstract

Long-term dynamics of the level of sexual dimorphism (SD) of body dimensions of newborns, embracing eight decades and inter- and intragroup variation, is under discussion. The study deals with a vast canvas of literary data – over 200 samples of newborns of each sex from former USSR and modern Russia through 1920-s till nowadays, including main anthropometric dimensions (body length and weight, chest and head girths). All samples are urban, the data is divided by decades, the number of each age/sex group as about 100 persons. Several levels of somatic variation were analysed: a) the whole data base above ethnic factor; b) only neighboring Slavonic groups; c) only Russian samples; d) regional Russian samples from Moscow and Kursk. The estimation of the level of SD is implemented using Kullback divergence, analogue of Makhalanobis distance. The results of meta-analysis, including the whole territory of Russia, witness to the definite secular sexual synchronism of dimension’s dynamics (increase of height/weight parameters and decrease of head girth), which results in very modest oscillations of SD around the level of 0,3 standard deviation. Still some secular decrease of SD is fixed for weight, due to more intensive increase of the parameter for girls, and for head girth, due to more intensive secular decrease of the parameter for boys. Some microsomisation of newborns is fixed in unfavorable war years 1940s and increase of SD due to greater decrease of the anthropometric parameters of girls (samples of Kursk). The same trend if fixed for Moscow newborns of 1960s, obviously above economic background, probably mediated by physical conditions of their mothers, who experienced economic depression of 1940s in their early childhood. Temporal fluctuations of SD level of main body dimensions of newborns keep within narrow interval 0,14-0,5 standard deviations, which does not exceed significant level of 0,3 standard deviations in the context of the study. This witnesses once again to the fact that the main factor of variation of newborns dimension is stabilizing selection, providing the stability of the dimensions of newborns of both sexes, as well as the level of sexual differences