Associations between 2D:4D from direct and radiographic measurements with handgrip strength in young adult Tuvans.

BACKGROUND: Digit ratio (2D:4D) - the relative lengths of the index and ring finger - is sexually dimorphic (male < female), possibly because of the sex-differentiated impact of prenatal androgenization on fetal development in the 1st trimester. The sex difference remains stable with age and has been reported in children, adolescents, and adults from industrialized and non-industrialized societies. Handgrip strength (HGS) also is sexually dimorphic (males > females) and correlates negatively with 2D:4D. AIMS: To examine in a sample of young adult Tuvans from Siberia (Russian Federation): i) the association between 2D:4D measured directly from the palms with 2D:4D measured from radiographic images of the same individuals and ii) the associations between 2D:4D and HGS in Tuvan men and women. STUDY DESIGN AND SUBJECTS: The study was cross-sectional. Participants were Tuvans (n = 185; 80 men; mean age = 21.02 years). 2D:4D was measured with a caliper from the ventral surface of the palm (both hands) and from radiographic images (left hand). HGS of both hands was measured with a digital hand dynamometer. Body height and weight were measured with an anthropometer and a body composition scale. RESULTS: 2D:4D ratios and anthropometric measures (including HGS) were sexually dimorphic. Men had lower 2D:4D and higher HGS than women. Direct measures of 2D:4D correlated positively with 2D:4D measured from radiographs. Body mass index (BMI) was a significant predictor of HGS for both sexes. Male right 2D:4D and female right and left 2D:4D correlated negatively with HGS after controlling for the influence of BMI. There were no associations with radiographic measurements of 2D:4D. CONCLUSION: Our findings provide evidence of sexual dimorphism in 2D:4D among young adult Tuvans. Together with previous research on Tuvan children and adolescents, these findings provide clear evidence of 2D:4D sexual dimorphism in pre- and postpubertal Tuvans. The small negative association between 2D:4D and HGS corresponds to similar reports across populations, suggesting that 2D:4D is a weak correlate of muscular fitness.

Direct and radiographic digit ratio (2D:4D) measurements of Tuvan children and adolescents from Southern Siberia: Sex differences and skeletal maturation.

BACKGROUND: In Mongolian-origin ethnic groups digit ratio (2D:4D; a proxy for prenatal sex-steroids) is sexually dimorphic (males < females), as reported for other ethnicities. Most studies measured 2D:4D from soft tissue (directly from the digits, or indirectly from hand scans), or from radiographs. Evidence on the correspondence of 2D:4D measurements from soft tissue with measurements from radiographic images is scarce and has not been reported for a Mongolian-origin sample. In addition, previous research has not considered relationships between 2D:4D and measures of skeletal maturity. AIM: To examine (i) associations between 2D:4D measured directly from the palms with those obtained from radiographic images of the same individuals in a sample of children and adolescents from the Tuvan population in Siberia (Russian Federation), and ii) associations between 2D:4D measurements with chronological and skeletal age. SUBJECTS AND METHODS: Participants were Tuvan boys and girls aged 7 to 18 years. 2D:4D of the right and left hand was measured from soft tissue (directly from the palm) and compared with radiographic images (left hand only). In addition to finger length 2D:4D, we examined 2D:4D of the phalanges from measurements of radiographs. Skeletal age was assessed using the Tanner-Whitehouse method. RESULTS: Sex differences (boys < girls) in measurements of 2D:4D from soft tissue and radiographs were found for total finger length and phalanges. In addition, 2D:4D measurements from radiographs correlated positively and significantly with those obtained from soft tissue. Sex predicted 2D:4D measurements from soft tissue and radiographs, but no effects of chronological/skeletal age and body height were detected. In girls (but not in boys), earlier skeletal maturity (relative to chronological age) was associated with higher 2D:4D in soft tissue measurements of both hands, radiographic 2D:4D, and 2D:4D of the proximal phalanges. CONCLUSION: Consistent with reports from other ethnic groups, 2D:4D in young Tuvans was sexually dimorphic, with boys having lower 2D:4D than girls. For girls, higher 2D:4D was found for participants whose skeletal age was more advanced than chronological age. This finding was obtained from direct soft tissue and indirect radiographic measurements. Age and body height were not associated with 2D:4D, which suggests differences in hormone developmental trajectories for 2D:4D and height.

Sex, population origin, age and average digit length as predictors of digit ratio in three large world populations.

Recently, a number of authors have claimed that sexual dimorphism in the second-to-fourth digit ratio (2D:4D) is simply dependent on digit length and is an artifact of allometry. The goal of our study is to verify the validity of these assumptions. The study sample comprised 7,582 individuals (3,802 men and 3,780 women) from three large world populations: Europeans (n = 3043), East Africans (n = 2844), and Central Asians (n = 1695). The lengths of the second and fourth digits on both hands were measured. Digit ratios were computed according to standard procedures. Analyses were conducted separately for each hand for the whole sample and in succession for the three large populations. Additionally, we separately tested four age cohorts (≤ 13, 14-18, 19-30, and 31 ≥ years) to test the effect of developmental allometry. The second and fourth digits showed strong positive linear relationships on both hands, and demonstrated an increase with age; digit length in women from the youngest age cohort was longer or equal to that of men, and shorter than men in older age cohorts. However, the 2D:4D magnitude and its sexual dimorphism remained stable throughout the ontogeny. To test for an allometric effect on 2D:4D, the average digit lengths were calculated. Both sex and population origin were permanent reliable predictors of 2D:4D, whereas average digit length was not. Height was applied as another measure of allometric effect on the limited sample (≤ 30 years) from the European population, along with sex and age. No allometric effect was observed in this case. We conclude that sex differences in 2D:4D are not an artifact of allometry.

Finger length ratio in longevity populations.

OBJECTIVES: The purpose of this study was to compare the prevalence of finger length ratio between three longevity populations (Abkhazians, Azerbaijanis, and Georgians) and one nonlongevity population (Russians), as well as between a longevity and nonlongevity sample within one ethnic group (Abkhazians). METHODS: In a cross-sectional observational study, we compared the prevalence of finger length ratio in longevity vs nonlongevity samples. RESULTS: A negative relationship was observed between longevity index and prevalence of type 1 (feminine type) ratio. In longevity samples, the prevalence of type 1 ratio was lower and the prevalence of type 3 (masculine type) ratio was higher than in the nonlongevity sample of Russians. This difference was statistically significant (P < .001) in both males and females. A similar difference between longevity and nonlongevity samples was exhibited in the Abkhazian samples. In males and females, a significantly higher prevalence of type 1 and lower type 3 finger ratios (P < .001) were shown in the nonlongevity samples. CONCLUSIONS: Finger length ratio pattern in longevity populations differs from that of nonlongevity populations. In longevity samples, the prevalence of type 1 ratio was lower and the prevalence of type 3 ratio was higher vs the nonlongevity sample. A similar type of difference was seen in the longevity and nonlongevity samples belonging to one ethnic group, the Abkhazians. Previous studies found that the type 1 finger length ratio was related to important morbidities that have a potential for shortening the life span. This can be one of the most plausible explanations for our findings.

Heritability estimation of 2D:4D finger ratio in a Chuvashian population-based sample.

OBJECTIVES: The purpose of this study was to evaluate the familial correlations and heritability of 2D:4D ratio traits using a large population-based sample of ethnically homogeneous pedigrees from Chuvasha and Bashkortostan Autonomies of the Russian Federation. METHODS: We calculated the familial correlations and performed a heritability analysis of 2D:4D ratio traits in a sample of 1541 subjects (803 men and 738 women, mean age 47.78 ± 16.89 years, range 18-90 years). RESULTS: Familial correlations of 2D:4D ratio traits showed no significant correlation for spouses; however, parent-offspring (0.15-0.28, P < .001) and sibling correlations (0.13-0.38, P < .009) were found to be significant. Heritability (H2 ) of visual classification of 2D:4D ratio was 0.36 for the left and 0.28 for the right hand; finger ratio was 0.55 and 0.66, respectively; the ray ratio was 0.49 and 0.59, respectively, thus indicating the existence of a clear familial aggregation of 2D:4D ratio variation in the Chuvashian pedigrees, which cannot be explained only by common environmental effects. DISCUSSION: Results of our study suggest familial aggregations of finger ratio variation (for all traits) in Chuvashian pedigrees. No evidence of assortative mating was found.

Finger Length Ratio and Body Composition In Chuvashians.

Very few studies that evaluated the association between fi nger length ratio and body composition in adult population showed very diverse results. We carried out a radiographic study on a large population sample who had participated in a Chuvashian skeletal aging study investigating different aspects of skeletal aging. The aims of this study were to evaluate the association between 2D:4D ratio and various indices of body composition in Chuvashian males and females. The study sample included 802 males (mean age 46.98±17.10 years) and 783 females (mean age 48.65±16.62 years). Single plain radiographs of both hands were taken. Each hand was classifi ed according to whether the index fi nger was longer (Type 1), equal to (Type 2) or shorter than the ring fi nger (Type 3) by visual comparison of the soft tissue outline of the fi nger ends on the radiograph. Anthropometry, including body weight, stature, and six circumferences from the body trunk and extremities were taken from each participant. We found no evidence of substantial associations between visually assessed fi nger length ratio and adult BMI, WC, hip and chest circumferences, WHT and WCR for men and women. These results suggest that associations between fi nger length ratio and hormone-related diseases and disorders can be interpreted directly, independent of any mediating effects of adult body composition parameters.

2D:4D finger length ratio and skeletal biomarker of biological aging.

ABSTRACT: The aim of this population-based study was to evaluate the association between the index to ring (2D:4D) finger length ratio and the osseographic score (OSS), the skeletal biomarker of biological aging. A sample included 802 males and 738 females who had participated in a Chuvashian skeletal aging study. Age, sex, basic demographics, anthropometric data and X-rays of both hands were collected. Each hand was visually classified on X-ray as either Type 1 - index finger was longer than ring finger; Type 2 - equal; or Type 3 - shorter than the ring finger. OSS is a skeletal biomarker that comprises osteoporotic and osteoarthritic changes observable on a hands X-ray. The mean age of males in the studies sample was 46.98 ± 17.10 and mean age females was 48.65 ± 16.62. OSS showed significant association with age (r = 0.886, p < 0.001), body mass index (BMI) (r-0.253, p < 0.001) and sex (F = 13.771, p < 0.001). Results of one-way ANCOVA for finger length ratio types of right hand showed a significant difference in OSS (d.f. = 2, F = 7.569, p = 0.001), after adjustment for age, sex, and BMI. The posthoc comparison showed that individuals with Type 3 (2D < 4D) ratio showed significantly higher OSS scores that ones with Type 1 (p = 0.012) and Type 2 (p = 0.003). In an analysis of finger length ratio types of left hand also a significant difference in OSS was found (d.f. = 2, F = 3.290, p = 0.038). The posthoc comparison showed that individuals with Type 3 (2D < 4D) ratio showed significantly higher OSS scores that ones with Type 2 (p = 0.33) ratio. Finger length ratio is associated with an OSS, a skeletal biomarker of biological aging. Individuals with Type 3 finger length pattern showed significantly higher OSS that ones with Type 1 and Type 2.

2D:4D finger length ratio and reproductive indices in a Chuvashian population.

OBJECTIVE: to evaluate the association between 2D:4D finger length ratios (representing the prenatal environment, i.e., early androgen exposure) and reproductive indices, such as age at menarche, menopausal age, and length of reproductive period. METHODS: Retrospective data on age at menarche and menopausal age as well as x-rays of both hands were obtained from 674 Chuvashian women aged 18-70 years (mean 46.32 ± 15.42). Finger and metacarpal length ratios as well as visual classification of finger ratio types, were estimated from the x-rays. RESULTS AND CONCLUSIONS: We found that a low 2D:4D ratio (radiologically evaluated), a masculine 2D:4D ratio type (visually evaluated), and a putative bioassay for prenatal androgen exposure, were associated with a later menarche and a shorter reproductive period. No association was found with menopausal age.

Morpho-physiological features of human populations in the context of climatic--geographical conditions.

This paper is based on the data obtained in the course of population studies conducted in 33 geographical regions of the former USSR territory by the faculty of the Anuchin Research Institute and Museum of Anthropology, Lomonosov Moscow State University, between 1961 and 1991. The data resulting from study of 4386 male and 4626 female subjects aged 17 to 99 include head and body morphology, bone mineral density, blood oxygen saturation and blood biochemistry. We aimed at studying the link between the traits of a population and the climatic conditions of the area inhabited by this population. Individual characteristics of the subjects were normalized by age and sex, and factor analysis was used to reduce the number of cross-correlating features. As a result, several integral characteristics (factors) were identified: five body morphology-related factors, two head morphology-related factors, one bone mineral density-related factor, one blood oxygen saturation-related factor and three blood biochemistry-related factors. These factors explained 79.3%, 78.38%, 63.51%, 74.4% and 66.77% of the trait groups' variability, respectively. The correlation analysis between these factors and climatic indicators demonstrated that chest dimensions were the least tolerant to the climatic conditions among the morphological characteristics studied. Hemoglobin-protein ratios, as well as the factor that includes total cholesterol, were the most climate-dependent among the biochemical parameters. As far as our data show, blood serum oxygen saturation--the key factor determining the performance of the cardiovascular and respiratory systems--is also climate-dependent.

Hand osteoarthritis in longevity populations.

BACKGROUND AND AIMS: Previous studies have reported that centenarians escape the major agerelated diseases. No studies on prevalence and severity of osteoarthritis (OA) in longevity population have previously been reported. Because OA is associated with morbidity and mortality, we hypothesized that radiographic hand OA would generally be less prevalent and would develop at a later age in longevity populations vs non-longevity populations. Aim was to evaluate the prevalence and mode of development of radiographic hand OA in three longevity populations (Abkhazians, Azerbaijanis and Georgians) and in one non-longevity population (Russians). METHODS: Crosssectional observational study. Longevity index was calculated as a ratio of the number of individuals aged >90 years vs the number of people aged >60, expressed per mil (‰). A population with longevity index >40‰was considered as a longevity population. Radiographic hand OA was evaluated using the left hand radiograms in 14 joints according to Kellgren and Lawrence's (K-L) grading system. Each individual was characterized by the total number of affected (K-L≥2) joints (NAJ). Prevalence of hand OA was defined as the presence of at least one affected joint. Statistical analyses included prevalence estimation, linear, logistic and polynomial regressions, and ANOVA. RESULTS: A significant difference (p<0.003) in age standardized prevalence of hand OA was found between each pair of studied samples, except between Russians and Georgians and between Azerbaijanis and Abkhazians (p>0.05). The lowest age-standardized prevalence was found in Abkhazians, followed by Azerbaijanis and Georgians. The highest prevalence was found in Russians. ANOVA showed significant differences (p<0.01) between the age-adjusted means of NAJs. The lowest age-adjusted NAJ was found in the Abkhazian population, followed by Azerbaijanis and Georgians. The highest NAJ was found in Russians. CONCLUSIONS: We observed that the pattern of radiographic hand OA in longevity populations differs from the pattern in non-longevity populations. On average, first joints with OA appear at an older age, and progression of hand OA, measured by NAJ, is slower.

Radiographic hand osteoarthritis in two ethnic groups living in the same geographic area.

The aim of the study was to compare the prevalence of radiographic hand osteoarthritis (OA) and its association with age, sex, body mass index in two ethnic groups, Russian and Buryats who reside in the same geographic area. It was a cross-sectional observational study. The study population comprised ethnic Russians (N = 572) and Buryats (N = 327) from the Barguzinsky District of the Buryat Republic, Russian Federation. OA was evaluated in 14 joints of the left hand according to Kellgren and Lawrence's grading system. A diagnosis of OA was determined by the number of affected joints and by the presence of at least one affected joint. Statistical analyses included prevalence estimation, linear and logistic regressions, and chi(2) tests. Our major finding was that individuals of different ethnic groups, residing in the same location, have similar prevalence and severity of radiographic hand OA. Considering the results of our previous study, where we found significant differences in the prevalence and severity of hand OA between the Russian samples (same ethnicity) with diverse places of residence, we conclude that environmental factors play an important role in the development of hand OA.

Variation of skeletal biomarkers of biological aging in a Chuvashian population: a longitudinal study.

Osseographic score (OSS) is a skeletal biomarker of biological aging, based on assessment of the hand's radiographic features. The aims of the present cross-sectional and follow-up study were: 1) to evaluate age-related changes of OSS in a large Chuvashian cohort, and 2) to evaluate sex differences in age-related changes of OSS. This study reports on intersexual differences in the pattern of skeletal aging. The most prominent difference was in the rate of skeletal change, measured as average OSS difference per year. However, no differences were found in the age at which the first skeletal change occurred. The mean values of OSS were higher in males than in females in decades 3-5 of life, but afterwards they reversed. In a follow-up study, we found that sex differences regarding the rate of OSS change began in the fifth decade, but became statistically significant only in the sixth and seventh decades. Thereafter, the rate of OSS change again became virtually equal between sexes.

Comparative analysis of age prediction by markers of bone change in the hand assessed by roentgenography.

The major aim of this study was to develop an accurate method of age prediction for a wide range of ages based on the roentgenographic assessment of the hand bones. Such a method may be of particular interest in paleoanthropology and forensic medicine. The present paper provides the results of an analysis of individuals belonging to two ethnically different population samples: 1) Chuvasha (the Russian Federation), 293 males and 254 females, aged 18-91 and 18-86 years, respectively; and 2) Turkmenians (the Republic of Turkmenia), 257 males and 386 females, aged 18-82 and 17-83 years, respectively. The hands of study participants were roentgenographed with standard methodology. For each roentgenogram an equidistant osseographic score (OSS) including the descriptive criteria of bone age was estimated. In addition, an osteoarthritic and an osteoporotic score (OA and OP, respectively) were assigned to each individual. OA was a modification of the Kellgren/Lawrence scale, whereas the OP was locally developed. Results of the multiple logistic regression analysis clearly indicated that OSS is a strong predictor variable of an individual's age, with R reaching 0.93 in Chuvasha and 0.89 in Turkmenians (P < 0.001). The standard errors of estimate were approximately +/-5-7 years and compared favorably with most known methods of age assessment using bones. This study provides an efficient method of age prediction, with acceptable accuracy, and extends the upper limit of prediction to the age of 70 years. An additional finding of interest was the coexistence of OA and OP in the bones of the same hand. The observed correlation between these two conditions reached 0.8 (P < 0.001). Am. J. Hum. Biol. 11:31-43, 1999. Copyright 1999 Wiley-Liss, Inc.