American Journal of Human Biology最新文献

{"title":"Oxidative Stress and Its Relationship With Market Integration and Pathogen Exposure Among Indigenous Shuar Children of Amazonian Ecuador","authors":"Anna Samsonov,&nbsp;J. Josh Snodgrass,&nbsp;Melissa A. Liebert,&nbsp;Felicia C. Madimenos,&nbsp;Elizabeth Y. Kim,&nbsp;Marcela Pfaff Nash,&nbsp;Lawrence S. Sugiyama,&nbsp;Samuel S. Urlacher","doi":"10.1002/ajhb.70206","DOIUrl":"10.1002/ajhb.70206","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Oxidative stress (OS) plays a key role in human aging and lifelong health. Problematically, little attention has been given to OS during childhood or outside of wealthy, industrialized populations. This limits understanding of the lifestyle and environmental factors that may drive global variation in childhood OS. Here, we present multifaceted urinary OS data from Indigenous Shuar children of Amazonian Ecuador to examine how children's OS is influenced by: (1) broad differences in market integration (MI; rural vs. peri-urban living); (2) household-level predictors of pathogen exposure; and (3) physiological measures of pathogen burden (immune activity) and adversity (cortisol).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Anthropometrics, household questionnaire data, and biospecimens (urine and finger-prick dried blood spots) were collected cross-sectionally from rural (<i>n</i> = 43) and peri-urban (<i>n</i> = 34) Shuar children, ages 4–12 years. 8-hydroxy-2′-deoxyguanosine (8-OHdG; a measure of oxidative damage) and total antioxidant capacity were measured in urine, and the overall oxidative stress index (OSI) was calculated. Predictors of OS were assessed using regression models.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Peri-urban Shuar children had, on average, 45% lower OSI than rural children (<i>p</i> = 0.002). Household pathogen exposure variables, including lack of running water and a greater number of resident individuals, predicted greater child OS (multiple <i>p</i> &lt; 0.05). Children's physiological measures of pathogen burden (circulating total immunoglobulin E) and adversity (urinary cortisol) similarly predicted greater OS (multiple <i>p</i> &lt; 0.05).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>These findings suggest that MI, including its impact on pathogen exposure and physiology, is an important driver of global variation in childhood OS and related disparities in phenotype and health.</p>\u0000 </section>\u0000 </div>","PeriodicalId":50809,"journal":{"name":"American Journal of Human Biology","volume":"38 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12837346/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146054847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reduced Fat Oxidation as a Potential Pathway Linking Early-Life Adversity to Obesity Risk: Evidence From Vanuatu","authors":"Md. Khaled Bin Oli Bhuiyan,&nbsp;Patrick Baca,&nbsp;Elena Hinz,&nbsp;Eddy Kiel,&nbsp;Krishna K. Kotra,&nbsp;Peter Mattison,&nbsp;Amanda McGrosky,&nbsp;Denise Mercado,&nbsp;Herman Pontzer,&nbsp;Cecilia M. T. Sena,&nbsp;Mary C. Towner,&nbsp;Katherine Wander,&nbsp;Ian J. Wallace,&nbsp;Siobhán M. Cully","doi":"10.1002/ajhb.70208","DOIUrl":"10.1002/ajhb.70208","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Adverse environmental conditions during early life can increase the risk of obesity in adulthood, but the underlying mechanisms are not completely understood. Here, we test the hypothesis that early-life adversity leads to a lower metabolic rate and reduced fat oxidation, factors expected to increase fat accumulation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We used data collected from 80 children and adolescents (aged 6–15 years; <i>n</i> = 39 females) living in Vanuatu. Relative lower limb length, calculated as the ratio of lower limb length to stature, was used as a surrogate measure of each individual's early-life environmental conditions, with a shorter relative lower limb length considered indicative of greater adversity. Fasting resting metabolic rate (RMR) and respiratory quotient (RQ) were measured with indirect calorimetry, and a higher RQ value was considered indicative of a lower rate of fat oxidation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>We found that, in a linear mixed-effects model including age, sex, and fat-free body mass as fixed effects and community and family as random effects, relative lower limb length was not significantly associated with RMR (<i>p</i> = 0.95). However, in a separate model, relative lower limb length was significantly negatively associated with RQ (<i>p</i> = 0.036), after accounting for the same fixed and random effects.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The latter finding suggests that adverse environmental conditions during early life may lead to reduced fat oxidation, which has the potential to increase the risk of obesity later in life. This finding might partially explain the so-called double burden of malnutrition (the co-occurrence of undernutrition and obesity) currently affecting many low- and middle-income countries.</p>\u0000 </section>\u0000 </div>","PeriodicalId":50809,"journal":{"name":"American Journal of Human Biology","volume":"38 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146041656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genetic Ancestry Reveals Historical Diversity of Formation Across Three Brazilian Communities of African Descent (Quilombos) in Central Brazil","authors":"Sabrina Guimarães Paiva,&nbsp;Anna C. Rivara,&nbsp;Matheus de Castro Nóbrega,&nbsp;Rafaela de Cesare Parmezan Toledo,&nbsp;Maria de Nazaré Klautau-Guimarães,&nbsp;Sidney Emanuel Batista dos Santos,&nbsp;Lorena Madrigal,&nbsp;Silviene Fabiana de Oliveira","doi":"10.1002/ajhb.70199","DOIUrl":"https://doi.org/10.1002/ajhb.70199","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Introduction</h3>\u0000 \u0000 <p>Characterized as relatively isolated communities, many Brazilian <i>quilombos</i> were formed during the period of slavery in Brazil when enslaved persons (most of African descent) ran away or were abandoned by their enslavers. <i>Quilombos</i> in Central Brazil, whose settlement was more recent due to the relative isolation of the region, remain understudied. To address this gap, this study estimated the genetic ancestry of three <i>quilombo</i> communities in Central Brazil.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A cross-sectional study was performed among three Central Brazilian <i>quilombos</i>, Cocalinho (<i>N</i> = 54) and Pé do Morro (<i>N</i> = 58) located in the Brazilian state of Tocantins, and Kalunga (<i>N</i> = 132) located in the state of Goiás. Genetic ancestry was estimated from 61 Ancestry-informative INDEL biallelic markers collected from blood samples and analyzed using STRUCTURE v 2.3. Statistical analyses were performed using SAS statistical software, v. 9.4.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The population demonstrated heterogeneous genetic admixture by <i>quilombo</i>. Average African admixture estimates were 36.75%, 29.82%, and 63.17% in Cocalinho (semirural), Pé do Morro (urban), and Kalunga (rural) communities, respectively. Indigenous and European ancestry contributions also varied by <i>quilombo</i>, with participants from the more recently populated <i>quilombos</i> and those living closest to urban areas having higher European and Indigenous genetic ancestry contributions.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This study demonstrates that <i>quilombos</i> comprise rich population histories shaped by culture, historical events, and sociodemographic and environmental interactions. By unraveling the genetic tapestry of Central Brazil's <i>quilombos</i>, this study contributes to a deeper understanding of Brazil's intricate social and historical landscape.</p>\u0000 </section>\u0000 </div>","PeriodicalId":50809,"journal":{"name":"American Journal of Human Biology","volume":"38 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajhb.70199","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146096579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Catch-Up Weight Gain and Gut Microbiota Development in Full-Term Small for Gestational Age Children During the First Year of Life—A Prospective Cohort Study","authors":"Magdalena Durda-Masny,&nbsp;Joanna Ciomborowska-Basheer,&nbsp;Norbert Grundmann,&nbsp;Marta Szymankiewicz-Bręborowicz,&nbsp;Monika Englert-Golon,&nbsp;Jan Mazela,&nbsp;Katarzyna Morańska,&nbsp;Izabela Makałowska,&nbsp;Wojciech Makałowski,&nbsp;Anita Szwed","doi":"10.1002/ajhb.70202","DOIUrl":"10.1002/ajhb.70202","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>Gut microbiota develops dynamically during infancy in parallel with early growth processes. This study aimed to assess the pattern of gut microbiota colonization in full-term SGA infants with catch-up weight gain in the 1st year of life.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>This longitudinal cohort study included 19 full-term SGA and 46 full-term appropriate-for-gestational-age (AGA) infants. Stool samples and body mass measurements were collected at multiple time points during the 1st year of life. Gut microbiota composition was analyzed using 16S rRNA gene sequencing. Alpha diversity, beta diversity, and taxa abundances were used to evaluate microbial composition and diversity across developmental stages. Associations between the rate of weight gain and the pace of gut microbiota maturation were examined.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>SGA infants exhibited higher alpha diversity than AGA children at most time points. In this group, the Shannon index, reflecting the level of gut microbiota maturation, was positively associated with the rate of body weight gain over time (<i>p</i> = 0.015), an association that was not observed in AGA infants. Characteristic genera associated with SGA included <i>Citrobacter, Staphylococcus, Blautia, Veillonella, Klebsiella</i>, and <i>Clostridium XIVa</i>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>SGA children had a distinct gut microbiota with higher alpha diversity than AGA peers. In this group, more mature microbiota was linked to faster weight gain and an increased abundance of short-chain fatty acid–producing and obesity-associated bacteria, suggesting that early microbial development may affect the risk of overweight and obesity later in life.</p>\u0000 </section>\u0000 </div>","PeriodicalId":50809,"journal":{"name":"American Journal of Human Biology","volume":"38 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajhb.70202","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146020469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mining the Gaps: Rethinking Divergence Between Biological and Self-Report Measures in the Study of Sexual Diversity","authors":"Lisa M. Diamond","doi":"10.1002/ajhb.70201","DOIUrl":"10.1002/ajhb.70201","url":null,"abstract":"<p>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 <i>diverge from</i>—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 <i>and</i> 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 <i>multiple</i> 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.</p>","PeriodicalId":50809,"journal":{"name":"American Journal of Human Biology","volume":"38 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12820751/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146013114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Proceedings of the Human Biology Association's 50th Annual Meeting, Baltimore Marriott Waterfront, Baltimore, Maryland, March 12th–14th, 2025","authors":"Tara J. Cepon-Robins","doi":"10.1002/ajhb.70198","DOIUrl":"10.1002/ajhb.70198","url":null,"abstract":"","PeriodicalId":50809,"journal":{"name":"American Journal of Human Biology","volume":"38 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145991699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ecologies of Risk: Malaria and Settler Landscape Transformation in 19th-Century Ontario","authors":"Amanda Cooke,&nbsp;Megan B. Brickley","doi":"10.1002/ajhb.70181","DOIUrl":"10.1002/ajhb.70181","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objectives</h3>\u0000 \u0000 <p>This study examines how settler-driven environmental change shaped malaria transmission and mortality in 19th-century southern Ontario. It aimed to understand the biosocial and ecological conditions that sustained endemic malaria in a temperate, colonial context.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>We analyzed 2702 deaths attributed to probable malaria from 1831 to 1900 using civil, cemetery, parish, and municipal records. Each record was coded for age, sex, occupation, region, and season of death. To assess environmental influences, we incorporated monthly temperature and rainfall data from Toronto as a regional climate proxy. We examined demographic and spatial patterns at multiple scales, including towns, settlement type (urban/rural), and regional groupings, alongside temporal and seasonal variation. Statistical comparisons were used to explore associations, including nonlinear modeling of rainfall and malaria mortality.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Probable malaria mortality declined over time but persisted throughout the century. Children under 5 accounted for over half of recorded deaths, while adults in agricultural occupations were also disproportionately affected. Rural areas, particularly in western Ontario, experienced the highest mortality. Generalized additive model (GAM) results indicated a strong nonlinear association between rainfall and malaria deaths (<i>p</i> &lt; 0.001), while temperature was not a significant predictor.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Malaria's persistence in 19th-century Ontario reflected a structural embedding of disease risk within settler-transformed landscapes. Deforestation, altered hydrology, and agricultural intensification created ecologies conducive to mosquito breeding. Vulnerability was not evenly distributed but shaped by age, labor, and proximity to altered environments. These findings underscore the importance of integrating environmental and historical data to reconstruct past disease ecologies and illustrate how evolutionary mismatch can drive vulnerability even in short-lived endemic contexts.</p>\u0000 </section>\u0000 </div>","PeriodicalId":50809,"journal":{"name":"American Journal of Human Biology","volume":"38 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajhb.70181","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145949266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction to “Doing Science With Our Grandmother's WISDOM: A Worldview Integrating Sociality, Diversity, and Observant Meaning-Making”","authors":"","doi":"10.1002/ajhb.70190","DOIUrl":"10.1002/ajhb.70190","url":null,"abstract":"<p>Dajani, R., D. Glass, and A. Fuentes. 2025. “Doing Science With Our Grandmother's WISDOM: A Worldview Integrating Sociality, Diversity, and Observant Meaning-Making.” <i>American Journal of Human Biology</i> 37: e70138. https://doi.org/10.1002/ajhb.70138.</p><p>The affiliation for the author Rana Dajani was missing “Faculty of Science”. The affiliation should read as follows:</p><p>Department of Biology and Biotechnology</p><p>Faculty of Science</p><p>The Hashemite University</p><p>Zarqa, Jordan.</p><p>We apologize for this error.</p>","PeriodicalId":50809,"journal":{"name":"American Journal of Human Biology","volume":"38 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/ajhb.70190","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145936035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Letter to the Editor: Association of Air Pollution With Adiposity Rates in Active Runners and Inactive People","authors":"Magno Conceição Garcia,&nbsp;Tatiane Cristina Moraes de Sousa","doi":"10.1002/ajhb.70195","DOIUrl":"10.1002/ajhb.70195","url":null,"abstract":"","PeriodicalId":50809,"journal":{"name":"American Journal of Human Biology","volume":"38 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145918998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The First Allometric Analysis in Newborns Rejects the Allometry Hypothesis for 2D:4D: Strong Developmental Evidence for Prenatal Hormonal Programming","authors":"Barış Özener,&nbsp;Berna Ertuğrul,&nbsp;Görel Aksoy","doi":"10.1002/ajhb.70193","DOIUrl":"10.1002/ajhb.70193","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objective</h3>\u0000 \u0000 <p>This study aimed to evaluate the presence of sexual dimorphism in the second-to-fourth digit length ratio (2D:4D) and to systematically investigate the contribution of potential allometric interactions to this variation in a sample of Turkish newborns (<i>N</i> = 225, 125 girls). Investigating newborns provides a unique opportunity to determine whether 2D:4D sexual dimorphism is primarily shaped by prenatal hormonal programming or by postnatal growth-related allometric interactions.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>Digit lengths (2D and 4D) were measured for both hands with 0.01 mm precision. Statistical analyses included ANOVA, Kruskal–Wallis, Spearman correlation, and Analysis of Covariance (ANCOVA), utilizing the mean 4D length as a covariate to isolate the size effect.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Male newborns exhibited significantly lower right and left 2D:4D ratios compared to females (right <i>d</i> = 0.68; left <i>d</i> = 0.80). Although males had significantly longer 4D lengths, ANCOVA results demonstrated that the sexual dimorphism in the 2D:4D ratio remained significant and independent of the 4D size effect (Right <i>p</i> = 0.003; left <i>p</i> = 0.001). Furthermore, when 4D length was statistically controlled, 2D length itself significantly differed between sexes, suggesting independent hormonal influence on 2D development.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The findings provide evidence for sexual dimorphism in 2D:4D in Turkish neonates. In this respect, the sex difference appears to be independent of the absolute length of the fourth digit, providing developmental evidence that is inconsistent with the allometry hypothesis and supporting the premise that 2D:4D dimorphism is likely related to prenatal hormonal programming rather than simple differential growth.</p>\u0000 </section>\u0000 </div>","PeriodicalId":50809,"journal":{"name":"American Journal of Human Biology","volume":"38 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145918944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}