Matsuo LH, Ceolin G, de Assis Guedes de Vasconcelos F
… +3 more, Silva DAS, Biazzi Leal D, de Fragas Hinnig P
Am J Hum Biol
· 2026 Mar · PMID 41826258
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OBJECTIVES: Changes in the timing of puberty may reflect shifts in population health, including the rising prevalence of overweight and obesity. Therefore, this study aimed to analyze the longitudinal association between...OBJECTIVES: Changes in the timing of puberty may reflect shifts in population health, including the rising prevalence of overweight and obesity. Therefore, this study aimed to analyze the longitudinal association between body mass index (BMI) in childhood and pubertal development 5 years later among Brazilian students. METHODS: This longitudinal study included 494 students aged 7-10 years. Data were collected in 2007 and 2012. BMI z-scores were calculated. Pubertal development was self-assessed using Tanner stages, and girls reported age at menarche. Structural equation modeling was used to assess the effects of the 2007 BMI on sexual maturation (SM) in 2012, adjusting for socioeconomic status (SES), birth weight, breastfeeding, physical activity, and dietary patterns (DP). RESULTS: No statistically significant association between BMI and SM was observed in either sex. Among boys, higher adherence to DP IV (milk, coffee with milk, cheese, breads/biscuits) (β = -0.21) and higher SES (β = -0.21) were associated with normal/late SM. Among girls, a higher 2007 BMI z-score (β = -0.27) had a direct negative effect on age at menarche, while DP II (ultra-processed foods) showed an indirect negative effect on age at menarche, mediated by the 2007 BMI z-score (β = -0.05). CONCLUSIONS: This study found that in girls, higher childhood BMI was associated with an earlier age at menarche. In boys, DP IV and SES were associated with normal/late SM. These findings highlight the significance of monitoring puberty timing at the population level and the need for sex-sensitive, prospective research to elucidate the determinants of earlier puberty, especially in low- and middle-income countries.
Am J Hum Biol
· 2026 Mar · PMID 41821265
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BACKGROUND AND OBJECTIVES: Caste division and socioeconomic deprivation among marginalized communities in Indian Hindu society, since the pre-independence period, necessitate further investigation into the inequality in...BACKGROUND AND OBJECTIVES: Caste division and socioeconomic deprivation among marginalized communities in Indian Hindu society, since the pre-independence period, necessitate further investigation into the inequality in undernutrition prevalence between upper caste (UC) and marginalized children. This study aims to estimate the gap in overall undernutrition prevalence between UC and Scheduled Caste/Scheduled Tribe (SC/ST) children in traditional Hindu society from 2005 to 2021. Additionally, it seeks to quantify the contributions of various factors-including child, maternal, household, and regional backgrounds-in explaining the gap of undernutrition between UC and marginalized children over the past 15 years. METHODS: The study employed three rounds of the National Family Health Survey Data (NFHS-3, 4, and 5) and estimated the prevalence of undernutrition using the Composite Index of Anthropometric Failure (CIAF). The Fairlie decomposition method was utilized to estimate persisting inequality and quantified contributions of different background variables in explaining the inequality between UC and SC/ST children in the prevalence of CIAF. RESULTS: Although the CIAF gap between Hindu UC and SC/ST children has declined from 2005-2006 to 2019-2021, it remains substantial, falling from 19.28% to 14.67% points between Hindu UC and SC, and from 22.46% to 18.42% points between Hindu UC and ST from 2005-2006 to 2019-2021. The influence of background variables in explaining the CIAF gap between Hindu UC and SC/ST children has declined from 2005-2006 to 2019-2021, indicating an increasing impact of unmeasured determinants over time. This study also highlights the substantial roles of household socioeconomic status, maternal education, household WASH conditions, child anemia levels, and birth order in explaining the CIAF gap between Hindu UC and SC/ST children over the past decade. CONCLUSIONS: The outcome of the study suggests interventians to reduce socioeconomic inequality between UC and SC/ST sections and adequate measures to improve mothers' education level, household WASH conditions, and childhood anemia among marginalized sections for reducing inter-group differences in the prevalence of childhood undernutrition in India.
Am J Hum Biol
· 2026 Mar · PMID 41820011
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OBJECTIVES: To test whether the universal two-parameter DS model, originally proposed in 2015, can accurately describe how human brain and body mass change from conception to old age and reproduce their complex allometri...OBJECTIVES: To test whether the universal two-parameter DS model, originally proposed in 2015, can accurately describe how human brain and body mass change from conception to old age and reproduce their complex allometric relationship. METHODS: We analyzed published autopsy data on brain and body mass from conception to ~90 years, encompassing both sexes. Using nonlinear least-squares regression in Maple, we fitted the DS model to the data, testing single- and two-stage growth scenarios. Model performance was evaluated via residual analysis. RESULTS: A two-stage model-with a transition at ~1.5 years post-conception-accurately described both brain and body mass trajectories (typically within 10% error). The model successfully reproduced the non-monotonic, "hook-shaped" allometric curve of brain vs. body mass, including age-related declines after ~45 years. Furthermore, rescaling age using development time (derived from the DS model) largely eliminated sex differences in body mass trajectories and equalized male and female life expectancy in biological time. CONCLUSIONS: The DS model provides a parsimonious, scientifically well-grounded framework for human ontogenetic growth. It identifies ~1.5 years post-conception as a critical developmental transition and offers a physiologically meaningful time metric with potential applications in theoretical biology, evolutionary anthropology, biogerontology, etc.
Am J Hum Biol
· 2026 Mar · PMID 41772909
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OBJECTIVE: Global reproductive transitions are well documented, yet less is known about how neighboring populations with divergent histories and exposure to market integration (MI) experience them. This study examines ho...OBJECTIVE: Global reproductive transitions are well documented, yet less is known about how neighboring populations with divergent histories and exposure to market integration (MI) experience them. This study examines how sociocultural and economic proxies of MI predict variation in reproductive outcomes among indigenous Shuar and nonindigenous Ecuadorian mestizos (Colonos) from Amazonian Ecuador, focusing on menarcheal age, age at first birth, parity, breastfeeding duration, and contraceptive use. METHODS: Reproductive histories were collected from 360 Shuar and 205 Colono women (ages 15-90) between 2008 and 2014. General linear and Poisson regression models were used to assess effects of ethnicity, birth cohort, and MI indices (household-, market-, traditional-style-of-life) on reproductive outcomes; logistic regression determined predictors of contraceptive use. RESULTS: Shuar women experience earlier age at first birth (p ≤ 0.05) and higher parity (p ≤ 0.001) with little secular change. However, within more market-integrated Shuar households, earlier menarche (p = 0.04), and lower parity (p ≤ 0.001) were documented. By contrast, Colonos show secular increases in age at first birth and declines in parity (both p ≤ 0.05). In both populations, breastfeeding duration decreases over time (p = 0.006) and higher contraceptive use is associated with more market-integrated households (p = 0.03). CONCLUSIONS: Reproductive transitions in Amazonian Ecuador unfold at differing rates, reflecting different histories and degrees of MI. Colonos show clear secular shifts characteristic of reproductive transitions, whereas Shuar show emerging transitions only among more market-integrated households. Results support the context-specific nature of reproductive transitions and highlight value in disaggregated analyses to understand their dynamics.
de Mello DGA, Dos Anjos LA, Ravelli MN
… +2 more, Ferriolli E, Pfrimer K
Am J Hum Biol
· 2026 Mar · PMID 41740991
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BACKGROUND AND AIMS: Accurate measurement of total energy expenditure (TEE) is critical for maintaining energy balance and body weight. This study aimed to analyze differences in TEE assessed by the doubly labeled water...BACKGROUND AND AIMS: Accurate measurement of total energy expenditure (TEE) is critical for maintaining energy balance and body weight. This study aimed to analyze differences in TEE assessed by the doubly labeled water method (DLW-TEE), using food quotient (FQ) derived from self-reported 24-h dietary recalls, respiratory quotient measured by indirect calorimetry (RQ-IC), and usual respiratory quotient of 0.85 (RQ-0.85) based on Western-type diet intakes. METHODS: Secondary analysis from a cross-sectional study conducted in a sample of 41 independent (21 women) older people (≥ 60 years). FQ was obtained from three self-reported 24-h dietary recalls, RQ-IC was measured after an overnight fast under resting conditions. Repeated measures analysis of variance was used to compare differences in DLW-TEE calculated with FQ, RQ-IC, and RQ-0.85. RESULTS: DLW-TEE was significantly different between the three approaches (p = 0.025). The RQ approaches on DLW-TEE did not differ significantly between sexes (p = 0.325). The overall mean DLW-TEE RQ-0.85 was 2253 (SD = 529, 95% CI: 2086, 2420) kcal/day, DLW-TEE RQ-IC was 2251 (SD = 541, 95% CI 2090, 2431) kcal/day, and DLW-TEE FQ was 2208 (SD = 534, 95% CI 2039, 2376). DLW-TEE calculated with FQ significantly reduced TEE compared to the mean DLW-TEE with RQ-0.85 values (ΔTEE -45 kcal/day, p < 0.001). CONCLUSION: Self-reported dietary intake data may provide a more context-specific estimate of the FQ than relying solely on RQ from indirect calorimetry or the fixed RQ of 0.85 in DLW-based TEE calculations. Although the resulting differences in TEE are modest, they can lead to overestimation of energy requirements over time.
Costa FF, Dos Santos Silva KB, Simeone D
… +3 more, Guerreiro JF, Rodrigues RAC, Oliveira-Filho AB
Am J Hum Biol
· 2026 Mar · PMID 41740986
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Excess weight is a global public health issue related to the accumulation of body fat and can be caused by various factors. This study aimed to determine the prevalence and associated factors of excess weight among adult...Excess weight is a global public health issue related to the accumulation of body fat and can be caused by various factors. This study aimed to determine the prevalence and associated factors of excess weight among adults living in a coastal area of the Brazilian Amazon. Methods. This cross-sectional study included 407 adults residing in Bragança, Pará, northern Brazil. Socioeconomic, demographic, behavioral, and morbidity data were analyzed using Poisson regression to identify potential associations with excess weight. The prevalence of excess weight was 63.3%. Behavioral factors directly associated with excess weight included avoiding raw salads and boiled eggs. The outcome was associated with factors related to morbidity, such as hypertension and diabetes mellitus. However, walking to work was found to be a protective factor against excessive weight. The high prevalence of excess weight detected in this coastal Amazon region indicates a desire to prioritize this issue in local public health agendas. Implementing individual and community-based interventions can help reduce health risks and improve the population's quality of life.
Hill EC, Coakley KE, Riggs B
… +2 more, Templeton S, O'Donnell L
Am J Hum Biol
· 2026 Feb · PMID 41724586
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INTRODUCTION: Muscle quality metrics are useful indicators of physical activity and overall health but have been underexamined in pediatric samples. This study investigates associations between skeletal muscle area and d...INTRODUCTION: Muscle quality metrics are useful indicators of physical activity and overall health but have been underexamined in pediatric samples. This study investigates associations between skeletal muscle area and density, bone mineral density (BMD), and obesity-related factors in a pediatric autopsy sample from New Mexico. METHODS: We analyzed postmortem computed tomography (PMCT) data of individuals aged 5-20.99 years at time of death. Skeletal muscle indices-muscle area relative to stature-were measured for the psoas major and thigh muscles at femoral midshaft. Muscle density was also calculated using Hounsfield units at these sites. Multiple linear regression was used to test the relationship between these proxies of muscle quality to BMD, obesity, metabolic dysfunction-associated steatotic liver disease (MASLD), sex, race/ethnicity, age at death, and mode of death. RESULTS: Skeletal muscle indices and density were positively associated with femoral BMD in a pooled-sex sample and lumbar BMD in females. Skeletal muscle indices were positively associated with obesity and muscle density was negatively associated with levels of subcutaneous adiposity. A reduced psoas muscle index was significantly associated with MASLD in males. Males have greater skeletal muscle indices than females, but the sexes have similar muscle density. Native American individuals exhibited lower muscle indices compared to Hispanic and non-Hispanic White peers. CONCLUSIONS: Muscle quality is positively related to skeletal health in girls and negatively associated with MASLD in boys. These findings underscore the importance of early-life physical activity and structural context in shaping musculoskeletal health.
Loupias LL, Otero F, García Mancuso R
… +1 more, Valenzuela LO
Am J Hum Biol
· 2026 Feb · PMID 41724574
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OBJECTIVES: The main objective of the study is to characterize and test the hypothesis of a continuing trend toward homogenization in contemporary Argentine diet through stable isotope analysis, exploring regional variat...OBJECTIVES: The main objective of the study is to characterize and test the hypothesis of a continuing trend toward homogenization in contemporary Argentine diet through stable isotope analysis, exploring regional variation in the context of globalized food systems. It is expected that the distribution of stable isotopes will exhibit a limited range of values but still display some heterogeneity that allows differentiation of dietary patterns by region. METHODS: A total of 204 hair samples were collected from volunteer donors in Argentina and analyzed for the stable isotopes δC, δN, and δS. Statistical analyses and isotopic niche modeling using Bayesian ellipses were performed to determine dietary differences between regions and geographical factors influencing the distribution of stable isotopes. The ranges of variations in dietary choices (omnivores, vegetarians, and vegans) were also characterized. RESULTS: The analyses revealed significant differences in stable isotope values between regions, indicating that interregional heterogeneity in diet persists despite globalization and previous trends. Significant correlations were found between isotopic values and geographic variables. It was determined that δC and δN values vary significantly between omnivores, vegetarians, and vegans, allowing for the identification of differential consumption of proteins at an isotopic level. CONCLUSIONS: The study concludes that the contemporary Argentine dietary pattern is consistent with the global trend toward "delocalized" and "deseasonalized" diets, where global foods are produced locally. The study suggests that the homogenization process has not completely eliminated regional dietary particularities, as the effective incorporation into diets is mediated by cultural, economic, and logistical factors.
Howe ME, Wiley AS, Essandoh YE
… +1 more, Venier M
Am J Hum Biol
· 2026 Feb · PMID 41711127
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Increasing human exposure to environmental contaminants is a growing concern and has become an important factor within human biological variation and health outcomes. Yet, traditional exposure assessment methods are ofte...Increasing human exposure to environmental contaminants is a growing concern and has become an important factor within human biological variation and health outcomes. Yet, traditional exposure assessment methods are often limited in their ability to capture the complexity and variation of chemical exposure, or are invasive, costly, and challenging to apply in field-based research. Here, we introduce silicone wristbands as an innovative and noninvasive tool for measuring personal passive chemical exposure and highlight opportunities for their use in human biological research. The wristbands sequester organic chemicals across multiple media (e.g., air, water, dust) and capture both inhalation and dermal absorption. We describe how they work, how to deploy them in the field, how to extract and analyze the chemical composition, and their methodological advantages for human biological research. A case study assessing exposure to flame retardants and the relationship to body size among girls in Costa Rica demonstrates the application for human biological research in a tropical and remote setting. We argue that wristbands provide a noninvasive method for assessing individual exposomes and understanding how environments are embodied and become a meaningful axis of human biological variation. Additionally, they motivate interdisciplinary, ethical, and community-engaged research in diverse and hard-to-reach populations, aligning with future directions of the field of human biology.
Keestra S, Derkx I, Miabangana ES
… +3 more, Sikka G, Chaudhary N, Salali GD
Am J Hum Biol
· 2026 Feb · PMID 41708291
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OBJECTIVES: This study examined variation in bitter taste perception among BaYaka hunter-gatherers from the Republic of Congo, comparing individuals from the same population that were born and grew up in a forest ecology...OBJECTIVES: This study examined variation in bitter taste perception among BaYaka hunter-gatherers from the Republic of Congo, comparing individuals from the same population that were born and grew up in a forest ecology to those from a logging town. METHODS: Bitter-tasting phenotype was assessed in 112 BaYaka individuals using a paper-strip taste-detection task with single-concentration strips of phenylthiocarbamide (PTC) and thiourea (thiocarbamide). Participants were grouped by the place where they were born and grew up: forest camps or the town. Logistic regression was used to test associations between location, sex, age, and bitter taste perception. RESULTS: Town-born individuals were more likely to perceive both compounds as bitter than forest-born individuals (PTC: OR = 3.93, 95% CI: 1.75-9.17, p < 0.01; thiourea: OR = 4.44, 95% CI: 1.97-10.42, p < 0.01). No significant associations were found between bitter taste perception and sex or age. CONCLUSION: Bitter-tasting phenotype differed among BaYaka individuals, with higher proportions of bitter tasters among those born and raised in town compared to those from forest camps. These results suggest that early-life ecological context may contribute towards variation in bitter taste perception, which we hypothesize might be due to differences in exposure to bitter wild plant compounds.
Kociuba M, Kozieł S, Ignasiak Z
… +2 more, Rejman M, Chakraborty R
Am J Hum Biol
· 2026 Feb · PMID 41704223
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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...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.
Pfaff-Nash M, Ramirez AJ, Kim EY
… +6 more, Cantrell HN, Liebert MA, Madimenos FC, Snodgrass JJ, Sugiyama LS, Urlacher SS
Am J Hum Biol
· 2026 Feb · PMID 41703973
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OBJECTIVES: Intestinal function is an important but often overlooked aspect of human biological variation, with the intestines serving as both a barrier against external pathogens/contaminants and the primary conduit of...OBJECTIVES: Intestinal function is an important but often overlooked aspect of human biological variation, with the intestines serving as both a barrier against external pathogens/contaminants and the primary conduit of nutrient extraction from food. Impaired intestinal function among children is viewed as a key contributor to growth faltering globally. However, few studies have investigated children's intestinal function in rural settings or beyond infancy. To address this limitation, we conducted a pilot study to describe the intestinal function of school-age Indigenous Shuar children of Amazonian Ecuador and to assess the feasibility of implementing the widely utilized lactulose:mannitol (L:M) test of absorption and permeability with this group. METHODS: The urinary L:M test was performed with 23 rural-living Shuar children aged 4-12 years. Ultra-performance liquid chromatograph-high-resolution mass spectrometry was used to determine L:M ratios, lactulose recovery, and mannitol recovery. Age and sex patterns were investigated using linear regression models. RESULTS: Children's mean L:M ratio was 0.33 ± 0.32, a ratio comparable to values reported for children in other low- and middle-income settings. 35%-91% of children were categorized as having impaired intestinal function using common cut-off values. Children's lactulose (0.14% ± 0.17%) and mannitol (2.60% ± 2.22%) recoveries did not differ by sex but increased with age (p < 0.05) and indicated diminished intestinal absorptive capacity and increased permeability. CONCLUSIONS: Intestinal function appears to be considerably impaired among school-age Shuar children living in a low-resource, rural setting. Children living in unsanitary, non-industrialized contexts may routinely experience intestinal permeability-related immune activation and malabsorption-related energy/nutrient loss. More research is needed to explore the breadth of global variation in children's intestinal function and to investigate its many evolutionary and public health implications.
Ozdemir S, Galbarczyk A, Wachowicz A
… +4 more, Słojewska K, Klimek M, Jasienska G, Marcinkowska UM
Am J Hum Biol
· 2026 Feb · PMID 41703916
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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...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.
Am J Hum Biol
· 2026 Feb · PMID 41693621
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OBJECTIVES: To examine the sleep architecture (proportion of Light, Rapid Eye Movement (REM), and Deep Sleep) of rural villagers using noninvasive, wearable ŌURA rings. METHODS: From June to August 2023, we collected sle...OBJECTIVES: To examine the sleep architecture (proportion of Light, Rapid Eye Movement (REM), and Deep Sleep) of rural villagers using noninvasive, wearable ŌURA rings. METHODS: From June to August 2023, we collected sleep data from 30 participants (16 men, 14 women, 370 nights) using ŌURA rings. Regression models were used to investigate the effect of gender, age, household size, livestock presence, and temperature on sleep patterns and sleep architecture. RESULTS: Average Total Sleep Time (TST) in the community was 7.6 h (SD: 1.01). Average proportion (%) Light Sleep was 59.9%, % REM Sleep was 17.9%, and % Deep Sleep was 22.2%. Men who cared for livestock had significantly higher % Light Sleep and lower % REM sleep compared to men who did not have livestock. Presence of livestock did not significantly affect men or women's % Deep Sleep. Temperature was positively associated with % Light and negatively associated with % REM and % Deep Sleep. CONCLUSIONS: We found that men who were responsible for livestock tended to have more % Light Sleep and less % REM Sleep than men without livestock. Livestock presence did not affect women's % Light or REM sleep stages, and % Deep Sleep remained unchanged between groups. Temperature was associated with changes in all sleep stages. Our findings highlight the need for naturalistic studies investigating sleep architecture in non-industrialized settings.
Am J Hum Biol
· 2026 Feb · PMID 41693451
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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 o...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.