American Journal Of Human Biology[JOURNAL]
Sun
200 papers
Second to Fourth Digit Ratio (2D:4D) in Female Patients With Systemic Sclerosis: Evidence for Prenatal Androgen Exposure.
Akkoc RF, Karatas A, Oz B
Am J Hum Biol · 2026 Feb · PMID 41689275 · Publisher ↗
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, h...
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.
Inverse Association Between Betel Quid Use and Diabetes in Rural Bangladesh.
Sznajder KK, Shenk MK, Perez L … +7 more , Alam N, Raqib R, Kumar A, Haque F, Blumenfield T, Cully SM, Wander K
Am J Hum Biol · 2026 Feb · PMID 41685574 · Full text
OBJECTIVES: Betel quid is used as a mild stimulant in many parts of South and East Asia and the Pacific. In observational studies, its use has been associated with elevated risk for diabetes, but studies in animal models...
OBJECTIVES: Betel quid is used as a mild stimulant in many parts of South and East Asia and the Pacific. In observational studies, its use has been associated with elevated risk for diabetes, but studies in animal models suggest some component(s) of betel quid could reduce risk. METHODS: We assessed associations between betel quid use and diabetes (glycated hemoglobin, HbA ≥ 6.5%) among a cross-sectional sample of 410 men and 717 non-pregnant women in Matlab, Bangladesh. RESULTS: In multivariable logistic regression, betel quid use was inversely associated with diabetes among men (aOR: 0.45; 95% CI: 0.26, 0.79) but not women (aOR: 0.88; 95% CI: 0.51, 1.52). There was a dose-response relationship between frequency of betel quid use and diabetes among men (aOR: 0.73; 95% CI: 0.59, 0.89), but not women (aOR: 0.96; 95% CI: 0.77, 1.18). Betel quid use was inversely associated with diabetes as an ordinal variable (no diabetes/prediabetes/diabetes) among men (aOR: 0.55; 95% CI: 0.36, 0.82) and women (aOR: 0.66; 95% CI: 0.47, 0.94). Structural equation modeling suggested that some of the inverse association was mediated by food source (market vs. household production). CONCLUSIONS: These models support the hypothesis that betel quid use could decrease, rather than increase, risk for diabetes in the Bangladeshi context, particularly among men (who have more frequent betel quid use than women). Heterogeneity in betel quid preparation across settings, multifactorial effects of betel quid use, and publication bias may contribute to differences between these findings and other observational studies.
Navigating Change: Biocultural Dimensions of Feeding in a Pilagá Community Undergoing Lifestyle and Economic Transition in Argentina.
Olmedo SI, Valeggia CR, Palavecino C … +1 more , Pérez-Escamilla R
Am J Hum Biol · 2026 Feb · PMID 41668324 · Publisher ↗
OBJECTIVE: This research analyzed the interplay between diet and sociocultural influences in the food consumption patterns of the Pilagá people in Formosa, Argentina. METHODS: This cross-sectional mixed-methods study, co...
OBJECTIVE: This research analyzed the interplay between diet and sociocultural influences in the food consumption patterns of the Pilagá people in Formosa, Argentina. METHODS: This cross-sectional mixed-methods study, conducted in 2023, included all 59 family clusters in a Pilagá community. Food intake was assessed using three 24-h dietary recalls per household, while qualitative data were collected through semi-structured interviews, free-listing exercises, and participant observation. RESULTS: Dietary habits in the Pilagá community were notably limited in variety and nutritional content, with 71% of participants reporting they ate just two meals a day. Purchased white bread, water, and infusions were consumed daily. Despite the high proportion of processed foods, the diet shows some foraged wild food. Food holds multifaceted roles beyond its biological function, with traditional foods valued not only for nourishment but also for their perceived health benefits and cultural significance. CONCLUSION: This Pilagá community is experiencing a dietary transition toward westernized foods, driven by biosociocultural factors that mirror broader shifts in local food systems and consumption patterns.
Integrating Measures of Pollutant Exposure in Human Biology Research.
Schell LM, Gallo MV
Am J Hum Biol · 2026 Feb · PMID 41653036 · Publisher ↗
This toolkit paper describes the value of including pollutant measurements in human biology research and describes considerations to implement such research. Human biologists study populations that are exposed to a varie...
This toolkit paper describes the value of including pollutant measurements in human biology research and describes considerations to implement such research. Human biologists study populations that are exposed to a variety of pollutants including metals and organic compounds used in agriculture and pest control. These pollutants can affect biological outcomes investigated by human biologists. Considering the impact of one or more of these pollutants in our investigations involves careful attention to properties of each pollutant and how the body metabolizes and stores them. Assessing exposure to many metals and organic compounds is best done by bio-sampling, usually of blood, but other media include hair, fingernails, and urine. Appropriate sampling media differ by pollutant but many found in the bloodstream may be collected together though not necessarily stored in the same way and not analyzed in the laboratory by the same method. A team approach is recommended as specialized knowledge of the proper sampling, handling, and analysis of each toxicant is needed. Choosing a laboratory should consider at a minimum the range of congeners measured, the minimum detection level, and the turnaround time for results required for the analysis. Study participants are likely to be interested in their toxicant exposure. The distribution of results should include careful description and interpretation to allow non-scientists to understand and take action if needed. Litigation by study participants against polluters is possible making it necessary to scrupulously preserve records of collection and analysis for possible court subpoena.
Not All Stress Is the Same: Variable Associations Between Psychosocial Stressors and Urinary Cortisol Rhythms in a Small-Scale Subsistence Society.
Jud DC, Baettig V, Colby AE … +7 more , Debras C, Scaff C, Trumble BC, Hutchings L, Baumgarten MD, Ista AC, Jaeggi AV
Am J Hum Biol · 2026 Feb · PMID 41649230 · Full text
OBJECTIVES: Dysregulations of the hypothalamic-pituitary-adrenal (HPA) axis have been linked to adverse health outcomes such as obesity, cardiovascular disease, and diabetes. While research on the HPA axis is growing, fe...
OBJECTIVES: Dysregulations of the hypothalamic-pituitary-adrenal (HPA) axis have been linked to adverse health outcomes such as obesity, cardiovascular disease, and diabetes. While research on the HPA axis is growing, few studies have examined whether different types of stressors affect HPA functioning differently, and none have done so in small-scale subsistence populations. To do so, we measured HPA axis activity and various kinds of stressors among the Tsimane of Bolivia, a population with more traditional lifestyles and stressors including low caloric intake, social conflict, and market integration. METHODS: Participants were adults from three different Tsimane communities (n = 129, 57% women). For each participant, urinary cortisol (n = 303), corrected for specific gravity, was measured once at waking and at least once later on the same day to measure the diurnal slope. One hundred and twenty-five participants completed a questionnaire on culturally relevant psychosocial stressors in the Tsimane such as food insecurity, social conflicts, and economic problems. Multilevel Bayesian multivariate models assessed associations between stressor scores and cortisol levels. RESULTS: Diurnal variation in the HPA axis was differentially associated with each type of stressor. Food insecurity was associated with higher morning levels (median r = 0.08, p = 0.73) and a steeper diurnal slope (median r = -0.19, p = 0.83), while economic problems were associated with lower waking levels and shallower slopes (median r = -0.05; p = 0.64, median r = 0.12, p = 0.72). Higher morning levels and steeper slopes were also associated with better self-rated health (median r = 0.06; p = 0.66, median r = -0.10, p = 0.71). CONCLUSION: While many of these associations had high statistical uncertainty due to wide posterior distributions, the results overall emphasize complex relationships between perceived stressors and diurnal cortisol rhythms among a small-scale subsistence-based society. Future work employing longitudinal designs and higher-resolution sampling will be needed to clarify these trends.
Ribcage Morphology in Native South American Populations From Different Altitudes: Insights From a Global Comparative Framework.
López-Rey JM, D'Angelo Del Campo MD, Bettera Marcat G … +7 more , Arrieta M, Fabra M, Salega S, Mercolli P, Seldes V, García-Martínez D, Bastir M
Am J Hum Biol · 2026 Feb · PMID 41635124 · Full text
OBJECTIVES: Altitude shapes human morphology as highland populations must cope with cold and hypoxic environments. Although Andean highlanders have been proposed to exhibit larger and deeper ribcages, this idea is mainly...
OBJECTIVES: Altitude shapes human morphology as highland populations must cope with cold and hypoxic environments. Although Andean highlanders have been proposed to exhibit larger and deeper ribcages, this idea is mainly based on research using disarticulated skeletal elements or non-South American controls. The objective of this research is to study 3D ribcage configuration of native South American populations considering altitude and worldwide ribcage variation. METHODS: Ribcages of 37 adult South Americans (17 highlanders, 20 lowlanders) were reconstructed and analyzed using 3D geometric morphometrics. Shape variation was assessed through Procrustes MANOVA and PCA, while centroid size was used to test for size differences. Comparisons were also made with a sample of 92 adult worldwide lowlanders. RESULTS: South American highlanders and lowlanders show similar ribcage shapes, both exhibiting a deeper thorax than worldwide lowlanders. No significant differences in absolute ribcage size were detected between South American highlanders and lowlanders. However, a marked sexual dimorphism was observed in both groups, with males having wider and significantly larger ribcages than females. CONCLUSIONS: The pronounced ribcage depth in native South Americans could represent a population-specific trait maintained through long-term interactions, potentially advantageous in high-altitude settings but neutral in the lowlands. In addition, we propose that South American highlanders have a larger ribcage relative to their smaller body size compared to lowlanders. Finally, the larger and stockier male ribcage morphology in South Americans supports the notion of greater respiratory capacity and metabolic demands in males.
The Shuar Health and Life History Project: Overview at 20 Years and Introduction to the Special Issue.
Urlacher SS, Gildner TE, Sugiyama LS
Am J Hum Biol · 2026 Feb · PMID 41631359 · Full text
The Shuar Health and Life History Project (established in 2005) is an interdisciplinary, integrated field and laboratory research project with the Indigenous Shuar population in Amazonian Ecuador. Grounded in human biolo...
The Shuar Health and Life History Project (established in 2005) is an interdisciplinary, integrated field and laboratory research project with the Indigenous Shuar population in Amazonian Ecuador. Grounded in human biology, behavioral ecology, evolutionary psychology, evolutionary medicine, and global health, the SHLHP has three key research foci: (1) To identify how market integration (via effects on diet, pathogen exposure, lifestyle, etc.) impacts Shuar health and well-being; (2) To investigate (using evolutionary life history theory) how lifetime phenotype and health are shaped by adaptive energy allocation between competing life tasks; and (3) To test hypothesized human psychological and demographic adaptations, including aspects of sociality that are central to the evolutionary success of our species. To address these foci, the SHLHP has established long-term and mutually beneficial relationships with the Shuar and local collaborators, resulting in community-engaged data collection with more than 3500 participants and a wide range of research publications and policy contributions over the past 20 years. This special issue of the American Journal of Human Biology showcases 10 original SHLHP articles that span much of the project's intellectual breadth and represent important advances for understanding human biology, life history, and health. To serve as an introduction, here we provide essential background on the Shuar and the SHLHP, overview the ten included special issue articles, and discuss key research and impact goals for the next 20 years of the SHLHP.
The Metacarpophalangeal Pattern Profile: An Old Method With New Insights Into the Evaluation of Short Stature.
Maruichi MD, Destailleur BT, Apelbaum GM … +2 more , Longui CA, Kochi C
Am J Hum Biol · 2026 Feb · PMID 41623008 · Full text
OBJECTIVE: To characterize the metacarpophalangeal pattern profile (MCPP) of healthy children and adolescents from São Paulo, Brazil, and to establish percentile curves by chronological age (CA), bone age (BA), and sex u...
OBJECTIVE: To characterize the metacarpophalangeal pattern profile (MCPP) of healthy children and adolescents from São Paulo, Brazil, and to establish percentile curves by chronological age (CA), bone age (BA), and sex using the LMS method. Additionally, to compare these findings with previous population-based data and to apply the derived standards to patients with skeletal dysplasias. METHODS: Left hand and wrist radiographs were obtained from healthy individuals and age-matched patients with confirmed skeletal dysplasias. Tubular bone lengths were compared across CA and BA, against prior normative studies, and with dysplastic cohorts using Student's t-test. Patient Z-scores were calculated from LMS parameters generated from the healthy population. RESULTS: We analyzed 974 radiographs from healthy subjects and 83 from patients (18 hypochondroplasia, 27 achondroplasia, 14 osteogenesis imperfecta, 24 Turner syndrome). In healthy participants, hand bone lengths correlated significantly with CA and BA. Compared with international reference data, differences in mean metacarpal and phalangeal lengths were noted. Patients with achondroplasia and hypochondroplasia exhibited markedly reduced Z-scores relative to controls, whereas those with Turner syndrome showed reductions of up to 1.8 SD in the fourth metacarpal. Patients with osteogenesis imperfecta demonstrated no significant deviations. CONCLUSION: This study established MCPP reference percentiles for Brazilian children and adolescents using the LMS method. Bone measurements showed consistent associations with CA and BA. Although differences were observed relative to international cohorts, the generated standards effectively discriminated dysplastic phenotypes, particularly achondroplasia and hypochondroplasia, supporting the use of MCPP analysis as an adjunct tool for evaluating short stature and suspected skeletal dysplasias.
Racial and Ethnic Differences in Bone Mass in Pediatric Populations: A Systematic Review.
de Lima TR, Bim MA, De Marco JCP … +3 more , Gonzaga I, Miranda CC, Pelegrini A
Am J Hum Biol · 2026 Feb · PMID 41622979 · Publisher ↗
OBJECTIVES: The purpose of this study was to summarize the evidence regarding possible differences in areal bone mineral density (aBMD) and bone mineral content (BMC) across racial and ethnic groups of children and adole...
OBJECTIVES: The purpose of this study was to summarize the evidence regarding possible differences in areal bone mineral density (aBMD) and bone mineral content (BMC) across racial and ethnic groups of children and adolescents. METHODS: A systematic review was conducted using five electronic databases, supplemented by complementary searches of reference lists. Studies should have used dual-energy x-ray absorptiometry to assess bone mass in children and adolescents (aged ≤ 19 years) with no special clinical conditions. RESULTS: Of the 1791 articles initially identified, 26 were included. Whites had lower aBMD/BMC than Blacks in 60.2% (47/78) of the analyzed results. In racial/ethnic groups that did not include Blacks, aBMD/BMC values were lower when compared to Blacks or ethnic groups that included Blacks in 80.0% (8/10) of possible results. Most findings indicated a paucity of evidence regarding differences in aBMD/BMC between Whites and Asians, Pacific Islanders, Hispanics, and Mexican-Americans (percentage of results ≤ 50.0%). CONCLUSIONS: Based on the findings, it can be concluded that White children and adolescents have lower bone mass values compared to their Black peers. Racial and ethnic groups that do not include Black individuals also exhibit lower bone mass values compared to Black children and adolescents. Additionally, there appears to be no difference in bone mass between White children and adolescents and their Asian, Pacific Islander, Hispanic, and Mexican-American counterparts.
Oxidative Stress and Its Relationship With Market Integration and Pathogen Exposure Among Indigenous Shuar Children of Amazonian Ecuador.
Samsonov A, Snodgrass JJ, Liebert MA … +5 more , Madimenos FC, Kim EY, Nash MP, Sugiyama LS, Urlacher SS
Am J Hum Biol · 2026 Jan · PMID 41589666 · Full text
OBJECTIVES: 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 limit...
OBJECTIVES: 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). METHODS: Anthropometrics, household questionnaire data, and biospecimens (urine and finger-prick dried blood spots) were collected cross-sectionally from rural (n = 43) and peri-urban (n = 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. RESULTS: Peri-urban Shuar children had, on average, 45% lower OSI than rural children (p = 0.002). Household pathogen exposure variables, including lack of running water and a greater number of resident individuals, predicted greater child OS (multiple p < 0.05). Children's physiological measures of pathogen burden (circulating total immunoglobulin E) and adversity (urinary cortisol) similarly predicted greater OS (multiple p < 0.05). CONCLUSIONS: 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.
Reduced Fat Oxidation as a Potential Pathway Linking Early-Life Adversity to Obesity Risk: Evidence From Vanuatu.
Bhuiyan MKBO, Baca P, Hinz E … +11 more , Kiel E, Kotra KK, Mattison P, McGrosky A, Mercado D, Pontzer H, Sena CMT, Towner MC, Wander K, Wallace IJ, Cully SM
Am J Hum Biol · 2026 Jan · PMID 41578864 · Publisher ↗
OBJECTIVES: 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 adve...
OBJECTIVES: 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. METHODS: We used data collected from 80 children and adolescents (aged 6-15 years; n = 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. RESULTS: 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 (p = 0.95). However, in a separate model, relative lower limb length was significantly negatively associated with RQ (p = 0.036), after accounting for the same fixed and random effects. CONCLUSIONS: 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.
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.
Durda-Masny M, Ciomborowska-Basheer J, Grundmann N … +7 more , Szymankiewicz-Bręborowicz M, Englert-Golon M, Mazela J, Morańska K, Makałowska I, Makałowski W, Szwed A
Am J Hum Biol · 2026 Jan · PMID 41567078 · Publisher ↗
OBJECTIVES: 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...
OBJECTIVES: 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. METHODS: 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. RESULTS: 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 (p = 0.015), an association that was not observed in AGA infants. Characteristic genera associated with SGA included Citrobacter, Staphylococcus, Blautia, Veillonella, Klebsiella, and Clostridium XIVa. CONCLUSIONS: 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.
Mining the Gaps: Rethinking Divergence Between Biological and Self-Report Measures in the Study of Sexual Diversity.
Diamond LM
Am J Hum Biol · 2026 Jan · PMID 41560710 · Full text
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 sexu...
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.
Proceedings of the Human Biology Association's 50th Annual Meeting, Baltimore Marriott Waterfront, Baltimore, Maryland, March 12th-14th, 2025.
Cepon-Robins TJ
Am J Hum Biol · 2026 Jan · PMID 41542717 · Publisher ↗
Abstract loading — click title to view on PubMed.
Ecologies of Risk: Malaria and Settler Landscape Transformation in 19th-Century Ontario.
Cooke A, Brickley MB
Am J Hum Biol · 2026 Jan · PMID 41518111 · Full text
OBJECTIVES: 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 sust...
OBJECTIVES: 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. MATERIALS AND METHODS: 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. RESULTS: 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 (p < 0.001), while temperature was not a significant predictor. CONCLUSIONS: 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.
Correction to "Doing Science With Our Grandmother's WISDOM: A Worldview Integrating Sociality, Diversity, and Observant Meaning-Making".
Am J Hum Biol · 2026 Jan · PMID 41510654 · Full text
Abstract loading — click title to view on PubMed.
Genetic and Phenotypic Associations of the Polygenic Score of Delay Discounting and Life History Traits.
Fieder M, Huber S
Am J Hum Biol · 2026 Jan · PMID 41502178 · Full text
OBJECTIVES: Delay discounting reflects individual differences in future orientation and impulsivity and may relate to life-history strategies. Because delay discounting has a substantial genetic basis, we investigated wh...
OBJECTIVES: Delay discounting reflects individual differences in future orientation and impulsivity and may relate to life-history strategies. Because delay discounting has a substantial genetic basis, we investigated whether the polygenic score (PGS) for delay discounting is associated with genetic predispositions for key life-history traits-education, age at first birth, and number of children-and whether these relationships are reflected phenotypically. METHODS: We used data from the Wisconsin Longitudinal Study, including 2713 men and 2980 women of European ancestry with available genetic data. Linear regressions examined associations between the delay-discounting PGS and PGSs for educational attainment, age at first birth, and number of children. Parallel models assessed phenotypic associations with years of postsecondary education, age at first birth, and number of children. All models controlled for birth year and the first 10 genomic principal components. RESULTS: In both sexes, the delay-discounting PGS was strongly negatively associated with the PGSs for educational attainment and age at first birth, and positively associated with the PGS for number of children. Phenotypic associations were directionally consistent but substantially smaller: higher delay-discounting PGSs predicted fewer years of education, earlier first birth, and (marginally) more children. Explained variance ranged from approximately 4%-5% for education to 1%-2% for reproductive traits. CONCLUSION: Genetic and phenotypic associations between delay discounting, education, and reproductive timing align with predictions from fast-slow life-history theory. These findings suggest that behavioral tendencies related to impulsivity and future orientation share molecular genetic foundations with key life-history traits while leaving substantial scope for environmental influences.
Maternal and Environmental Influence on Birth Weight in Jujuy, Argentina (1991-2014).
Revollo GB, Figueroa MI, Dipierri JE … +2 more , Díaz MDP, Gómez ELA
Am J Hum Biol · 2026 Jan · PMID 41502176 · Publisher ↗
INTRODUCTION: Birth weight (BW) is a key indicator of intrauterine growth, influenced by maternal and environmental factors, including geographic altitude. This study analyzes the influence of maternal and socio-environm...
INTRODUCTION: Birth weight (BW) is a key indicator of intrauterine growth, influenced by maternal and environmental factors, including geographic altitude. This study analyzes the influence of maternal and socio-environmental factors on BW between 1991 and 2014 in the province of Jujuy, Argentina. METHODS: A total of 310 793 live births in Jujuy were analyzed, grouped by maternal region of residence. Mean BW was estimated, and the percentage distribution of maternal and gestational variables was described. Three-level generalized linear models were applied to assess the association between BW and these variables, accounting for longitudinal and spatial variability. RESULTS: Mean BW was lower in high-altitude regions, with an adjusted difference of ~150 g between highlands and lowlands (p < 0.001). Preterm births, adolescent mothers, and mothers not cohabiting with a partner were associated with lower average BW, while post-term births or mothers with lower educational attainment had higher BW. Adjusted models confirmed differential patterns by altitude, highlighting significant effects (p < 0.001) of maternal and gestational factors. CONCLUSION: In Jujuy, between 1991 and 2014, BW showed a significant association with geographic altitude and maternal factors such as age, marital status, and gestational age, with regional variations. Understanding and addressing these interactions is essential to reduce maternal and neonatal morbidity and mortality.
Letter to the Editor: Association of Air Pollution With Adiposity Rates in Active Runners and Inactive People.
Garcia MC, de Sousa TCM
Am J Hum Biol · 2026 Jan · PMID 41502162 · Publisher ↗
Abstract loading — click title to view on PubMed.
The First Allometric Analysis in Newborns Rejects the Allometry Hypothesis for 2D:4D: Strong Developmental Evidence for Prenatal Hormonal Programming.
Özener B, Ertuğrul B, Aksoy G
Am J Hum Biol · 2026 Jan · PMID 41502149 · Publisher ↗
OBJECTIVE: 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...
OBJECTIVE: 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 (N = 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. MATERIALS AND METHODS: 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. RESULTS: Male newborns exhibited significantly lower right and left 2D:4D ratios compared to females (right d = 0.68; left d = 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 p = 0.003; left p = 0.001). Furthermore, when 4D length was statistically controlled, 2D length itself significantly differed between sexes, suggesting independent hormonal influence on 2D development. CONCLUSION: 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.
About
- Frequency
- Sun
- Papers found
- 200
- RSS feed
- Subscribe