ИСТИНА

Introduction A recent study (Zheng and Cohn 2011), provided direct evidence that sexually dimorphic digit ratios are caused by both androgen and estrogen signaling . During the last decade, this phenomena has been examined in relation to a number of physiological processes and psychological aspects (Putz and others 2004), sporting abilities(Manning and Taylor 2001; Paul and others 2006b), and diverse health conditions (Manning and Bundred 2000; Vehmas and others 2006). Aims of the study were formulated as follows. 1) To present the mean values of male and female 2D:4D ratio in a Chuvashian population; 2) To examine the contributions of phalanges and metacarpals to the 2D:4D ratios; 3) To determine the symmetry between right and left 2D:4D ratios. 4) To evaluate the association between the 2D:4D finger length ratio (representing the prenatal environment, i.e., early androgen exposure) and reproductive indices, such as age at menarche, menopausal age and length of the reproductive period. Materials and methods 1,541 native Chuvashians residing in numerous small villages in the Chuvasha and Bashkortostan Autonomies of the Russian Federation were tested. Following indices were registered: 1) Sex, age, anthropometrical characteristics (height, weight), occupation, as well as the nature and extent of their physical activities. 2) Details on chronic morbidity and medical treatment (all persons with known bone disease, amenorrhea, or with posttraumatic, rheumatoid or psoriatic arthritis, as well as those subjected to hormone replacement therapy or steroid intake ,were excluded from the study); 3) Age at menarche, menopausal age, number of children; 4)X-rays of both hands were obtained from the study participants. Two methods were used to estimate 2D-4D ratio: 1) Measurements taken from the index and ring fingers of both hands: mid-point of the base of the proximal phalanx to the mid-point of the tip of the distal phalanx; and mid-point of the base to the mid-point of the tip of the metacarpal. 2) Visual comparisons of the length of 2nd and 4th based on soft tissue outline of the finger ends on the radiograph according to Type 1 : 2D>4D, Type 2 : 2D=4D and Type 3 : 2D<4D. Statistical analysis Mean and standard deviation for radiographic measurements and prevalence of visual classification types were calculated using descriptive statistics. The association between the measured 2D:4D data and age was evaluate using univariate (Person correlation) analyses and linear regression analysis, adjusted for sex. The association between visual classification type and age was evaluate using the Spearman correlation and linear regression analysis where age was a dependent variable and sex and visual classification type were independent variables. Symmetry between right and left measured 2D:4D length ratios were evaluated using the Pearson’s correlation analysis. The association between the measured 2D:4D data (phalangeal and metacarpal ratios of both hand), and age at menarche, menopausal age, reproductive period were evaluated using the Person’s correlation analysis. Reproductive indices were compared using analysis of variation (ANOVA) between three types of visual classification of the 2D:4D length ratios. The relationship between the reproductive indices and the visual classification was examined using a linearity test. Results The phalanges and metacarpals both contribute to the variation in the 2D:4D ratio. The phalangeal and metacarpal ratios differ between men and women, with the phalangeal ratio being smaller in men and the metacarpal ratio smaller in women. Measured and visually classified 2D:4D ratios are symmetric with no sex dimorphism found between the right and left hands. Conclusion Relatively increased prevalence of Type 1 ratio in young males and females probably indicates a secular trend toward a more feminine type of digital ratio in the Chuvashian population. This is a first time that the secular trend of visually classified 2D:4D ratio was found in any population and additional studies are needed to confirm if this trend exists in other ethnic groups. The low 2D:4D ratio (radiologically evaluated) and the masculine 2D:4D ratio type (visually evaluated), were associated with a later menarche and a shorter reproductive period. No association was found with menopausal age. The abstract represents a short description of the lecture given at “the International Research- to-Practice Conference: Anthropology of family: historical, socioeconomic and cultural aspects of researches” hold in Minsk in June 27-30, 2017. Detail information is presented in following publications: L. Kalichman, V. Batsevich, E. Kobyliansky. 2D:4D finger length ratio and reproductive indices in Chuvashian population. 2013; Am J Hum Biol. 2013;25(5):617-21. L. Kalichman, D. Zorina, V. Batsevich, E. Kobyliansky 2D:4D finger length ratio in Chuvashian population. 2013 Homo .Jun;64(3):233-40 L Kalichman, , V Batsevich, and E Kobyliansky . 2D:4D finger length ratio and skeletal biomarker of biological aging. Anthropologisher Anzeiger 2017 May 30 (Epub ahead of print)