American Journal of Human Biology最新文献

Objectives: Systemic sclerosis (SSc) demonstrates marked female predominance, suggesting hormonal influences in disease pathogenesis. The second-to-fourth digit ratio (2D:4D), a biomarker of prenatal androgen exposure, has been associated with various autoimmune conditions. This study investigated whether 2D:4D ratios differ between female SSc patients and healthy controls.

Methods: This case-control study enrolled 33 women with SSc (2013 ACR/EULAR criteria) and 30 age-matched healthy female controls. Second and fourth digit lengths were measured bilaterally using digital calipers, and 2D:4D ratios were calculated. Between-group differences were analyzed using Welch's t-test and Mann-Whitney U test.

Results: SSc patients demonstrated significantly lower 2D:4D ratios than controls bilaterally (right hand: 0.950 ± 0.029 vs. 1.022 ± 0.012, p < 0.001; left hand: 0.951 ± 0.030 vs. 1.022 ± 0.012, p < 0.001). Effect sizes were substantial (Cohen's d > 2.8). The lower ratios resulted from longer fourth digits rather than shorter second digits, consistent with elevated prenatal androgen exposure.

Conclusions: Female SSc patients exhibit significantly lower 2D:4D ratios than healthy controls, suggesting higher prenatal testosterone exposure. These findings support the hypothesis that the prenatal hormonal environment may contribute to autoimmune disease susceptibility.

Objectives: Exposure to sex hormones during the early stages of fetal development in the prenatal period is thought to affect the length ratio of the second and fourth fingers (2D:4D). The 2D:4D ratio remains a subject of significant interest, particularly in relation to diseases and conditions linked to gender differences. This study aims to compare the 2D:4D ratio of individuals with generalized joint hypermobility (GJH) to the ratio of individuals without GJH in a population of both male and female participants.

Methods: The study was conducted on 180 individuals (100 females), including 85 with GJH and 95 without GJH (controls). Joint hypermobility was assessed using the Beighton score. The 2D:4D ratio was calculated using a digital caliper. In addition, the height, weight, and body mass index of the participants were calculated.

Results: The 2D:4D ratio was significantly higher in individuals with GJH compared to controls. In males, the 2D:4D ratio was higher in both the right and left hands in the GJH group compared to controls (p < 0.05). In females, the 2D:4D ratio was also significantly higher in both hands in the GJH (p < 0.05). The Beighton total score showed moderate positive correlations with right- and left-hand 2D:4D ratios (r = 0.49 and r = 0.38, respectively; p < 0.001).

Conclusion: The 2D:4D ratio can be used as a potential biomarker for GJH. It is thought that the concentration of sex hormones in the prenatal period (2D:4D ratio) may affect joint hypermobility (connective tissue).

Trial registration: ClinicalTrials.gov: NCT07157930.

Introduction: Physical activity patterns across the menstrual cycle may reflect evolutionary adaptations that optimize reproductive success by aligning heightened activity with the fertile window and lowered activity in the luteal phase, when the female's body prepares for a possible pregnancy.

Methods: This study examined variation in physical activity patterns across five arbitrary phases of the ovulatory menstrual cycle in 77 healthy women (age: 20-36 years). Based on ovulation tests and the date of the next menstruation, the menstrual cycle was divided into five physiologically distinct phases: menstrual, follicular, peri-ovulatory, luteal, and premenstrual. Daily physical activity was measured using a wristband accelerometer that tracked step count and activity duration at various intensities: sedentary, light, moderate, and intense, and the total 24-h duration of activity. Differences among phases were analyzed by repeated measures ANOVA, with corrections for multiple comparisons.

Results: Step counts were higher in the follicular phase compared to the premenstrual phase (mean 10.2 vs. 8.9, respectively, p = 0.001), and total activity time was higher during the follicular phase than in the premenstrual phase (mean 99.3 vs. 90.8, p = 0.004). No other significant differences were observed.

Conclusions: Step count and total active time peaks in the follicular phase and declines during the premenstrual phase. Our study highlights the importance of accurately identifying phases of the menstrual cycle and analyzing various activity intensities for understanding physical activity behavior across the menstrual cycle.

Background: Variation in exposure to prenatal androgens was linked with athletic abilities and varied performance in different sports. The ratio between the second and fourth digit lengths (2D:4D) is a proxy indicator of prenatal testosterone exposure. A higher exposure leads to a lower 2D:4D and vice versa. Negative associations between digit ratio and several sports performances were consistent in earlier research.

Aim: The aim of the present study was to assess if 2D:4D was lower among the Polish competitive swimmers compared to non-sporting individuals and the heterogeneity in sex difference among different levels of swimmers and the non-sporting group.

Method: This cross-sectional study assessed 2D:4D among two groups of swimmers from the Polish national team and other higher level swimmers, and a control group (54 males and 34 females). Height, weight, and lengths of 2D and 4D were measured.

Results: The control group showed a significant sex difference in the right hand 2D:4D; the females showed a higher ratio than the males (t = 2.17, p < 0.05). However, no sex difference was evident in any of the swimmers' groups. The difference in 2D:4D among the three study groups was significant only for the left 2D:4D in males and only for the right 2D:4D in females. The female swimmers (both national and general) showed significantly lower right 2D:4D than the control females, whereas the male swimmers showed significantly lower left 2D:4D than the control males.

Conclusion: The swimmers had lower 2D:4D than non-sporting individuals; the top level swimmers had the lowest 2D:4D. The female swimmers, particularly the elite group, showed "masculine" 2D:4D similar to their male counterparts. A plausible positive selection for a masculinised digit ratio (higher prenatal testosterone exposure) among the females in highly competitive professional sports was hypothesized.

Over the past several decades, scholars have conducted hundreds of studies investigating potential biomarkers of sexual orientation, such as genes, neuroanatomical features, and patterns of physiological response to sexual stimuli. The findings have been inconsistent: Biological measures sometimes converge with—but just as often diverge from—individuals' self-reported sexual attractions, behaviors, and identities. For example, numerous studies show that individuals' biological responses to erotic stimuli frequently diverge from their self-reported sexual identities and self-reported arousal to such stimuli. I argue that such cases of “biodivergence” warrant a shift in our conceptualization of sexual orientation, from seeing it as a singular and coherent phenotype to seeing it as a constellation of multiple biobehavioral patterns, with multiple and divergent causes and effects. I show that this perspective concords with recent findings from genetic research on sexual orientation, which show there is no single genotype underlying patterns of same-gender expression, and also concords with recent population data showing increasingly varied and fluid forms of sexual diversity around the globe that challenge the notion of sexual orientation as a singular and coherent sexual phenotype.