American Journal Of Human Biology[JOURNAL]
Sun
200 papers
Toward New Directions in Human Biology: A Roadmap for Anthropological Causal Inference With Observational Data.
Watson EJ, Glass DJ, Petito LC
Am J Hum Biol · 2025 Sep · PMID 40977372 · Full text
Human biologists seek to understand how cultural, environmental, and biological forces shape observed patterns of human variation. Yet contemporary insights and approaches to observational causal inference remain underut...
Human biologists seek to understand how cultural, environmental, and biological forces shape observed patterns of human variation. Yet contemporary insights and approaches to observational causal inference remain underutilized in the field. We outline a structured but flexible roadmap for causal inference in human biology that begins with theory development, defines causal questions and estimands, employs directed acyclic graphs (DAGs) to clarify assumptions, and evaluates key identification criteria prior to statistical analysis. We position this framework within a spectrum of causal inference traditions, spanning from interventionist approaches rooted in well-defined, manipulable exposures to realized approaches that engage historically situated and ecologically embedded phenomena. Rather than offering a prescriptive checklist, we frame this toolkit as an opening: a step toward anthropological causal inference that integrates transparency, theoretical and methodological coherence, and the epistemological commitments of the biocultural synthesis in human biology and anthropology.
Time Trends in Adult Height Among Russian Males and Females (1966-2000) and Projections to 2050 in the Context of Changing Living Conditions.
Negasheva MA, Khafizova AA, Movsesian AA
Am J Hum Biol · 2025 Sep · PMID 40977254 · Publisher ↗
OBJECTIVES: To model the temporal dynamics of adult height among Russian males and females born between 1966 and 2000, in relation to changes in socio-economic and demographic indicators reflecting population living cond...
OBJECTIVES: To model the temporal dynamics of adult height among Russian males and females born between 1966 and 2000, in relation to changes in socio-economic and demographic indicators reflecting population living conditions. METHODS: The study is based on publicly available anthropometric, socio-economic, and demographic data. Time trends in adult height were examined using mean values recorded at age 19 for males and females born between 1966 and 2000. Eleven proxy variables representing environmental conditions (e.g., nutrition, health, and urbanization) were analyzed across the study period. Statistical methods included correlation analysis and multiple linear regression to identify key predictors of cohort-level height variation. RESULTS: From 1966 to 2000, adult height increased steadily up to the cohorts born in the late 1980s, declined in the 1990s, and rose again in the early 2000s. Regression models identified five key predictors most strongly associated with height trends: the share of urban population, life expectancy at birth, crude birth and death rates, and per capita meat consumption. A preliminary projection based on these models suggests a continued increase in average adult height for cohorts born through 2050. CONCLUSION: This study introduces original theoretical models that link time trends in adult height in Russia to long-term changes in environmental conditions shaped by major historical events in the latter half of the 20th century. The findings highlight the substantial impact of urbanization, nutritional status, and population health on physical growth outcomes. For the first time, these regression-based models have been used to generate a projection of adult height trends in the Russian population through 2050. The proposed framework offers valuable insight into the biological consequences of socio-economic transformation and provides a basis for future research and public policy aimed at supporting child development and improving population health.
Prevalence of Low EPHX1 Activity-Associated Genotypes in Himalayan Populations of India.
Rai D, De S, Das D … +9 more , Tamang S, Mandal K, Subba S, Sahithi LS, Reddy AG, Govindaraj P, Thangaraj K, Chaubey G, Tamang R
Am J Hum Biol · 2025 Sep · PMID 40974229 · Publisher ↗
OBJECTIVES: The EPHX1 gene encodes human microsomal epoxide hydrolase 1, which helps in biotransformation processes. Its activity is influenced by combinations of genotypes at its polymorphic sites. There are no data on...
OBJECTIVES: The EPHX1 gene encodes human microsomal epoxide hydrolase 1, which helps in biotransformation processes. Its activity is influenced by combinations of genotypes at its polymorphic sites. There are no data on the EPHX1 gene variants in the Indian Himalayan and adjoining populations (HAAPs). Therefore, this study aims to investigate the activity-associated genotypes of the EPHX1 gene variants in the HAAPs. MATERIALS AND METHODS: The EPHX1 activity-associated variants, located in exon 3 (Tyr113His) and exon 4 (His139Arg), were analyzed among 607 samples from 16 different HAAPs. Genotype data from previously published 14 Indian populations were combined and evaluated for pan-India comparison. RESULTS: We observed the prevalence of low EPHX1 activity-associated genotypes compared to the intermediate and high activity combinations in the HAAPs. There was a significant difference (p < 0.05) between the HAAPs and the reference Indian population based on variants in the EPHX1 gene. Comparison based on linguistic affiliation revealed that low EPHX1 activity-related genotypes were significantly higher in frequency among Tibeto-Burman speaking HAAPs (p < 0.001), followed by the other three major linguistic groups in India. CONCLUSION: Our study highlights the variations in both the studied loci among the HAAPs. We observed the widespread presence of low-activity-associated genotypes of the EPHX1 gene in the HAAPs. The pan-India comparison revealed the highest prevalence of low-activity-associated genotypes among the Tibeto-Burman speaking HAAPs compared to other linguistic groups. In the future, high-resolution genetic and molecular studies on EPHX1 are necessary to corroborate this finding and better understand human health holistically.
A 2-Year Follow-Up Study of Changes in Handgrip Strength in Young Athletes Playing With and Without Gripping Sports Equipment.
Abe T, Abe A, Loenneke JP
Am J Hum Biol · 2025 Sep · PMID 40974227 · Publisher ↗
OBJECTIVES: This study compared changes in handgrip strength (HGS) over 2 years in young athletes participating in two sports: kendo, which involves gripping equipment during play, and soccer, which does not. METHODS: On...
OBJECTIVES: This study compared changes in handgrip strength (HGS) over 2 years in young athletes participating in two sports: kendo, which involves gripping equipment during play, and soccer, which does not. METHODS: One hundred eleven young athletes (54 kendo boys [mean age at baseline: 10.1 ± 1.7 years] and 57 soccer boys [mean age at baseline: 10.3 ± 1.8 years]) underwent three HGS measurements, spaced 1 year apart (Test 1, Test 2, and Test 3). The Q-Q plot indicated some violations of normality; therefore, we used a robust repeated measures ANOVA function in R. RESULTS: We found evidence for a localized interaction effect (p = 0.02), with a sport difference in the change from Test 1 (baseline) to Test 3 and Test 2 to Test 3 (kendo > soccer). There was no statistically significant main effect of sport (p = 0.06); however, kendo was on average 2.4 (95% CI: -0.08, 4.9) kg stronger than soccer athletes. When collapsing across groups, HGS increased from Test 1 to Test 2 by 1.9 (1.5, 2.3) kg, and from Test 2 to Test 3 by 2.8 (2.1, 3.6) kg. CONCLUSIONS: Sports that involve gripping tools in conjunction with natural movements may help improve HGS during the developmental period.
Minoritized and Poorly Understood: A Scoping Review of Mental and Physical Health Among Arab Adolescents in Canada and the United States.
Glass DJ, Alsamawi H, Fairclough-Dick A … +3 more , Ahmad A, Taye M, Shaoob M
Am J Hum Biol · 2025 Sep · PMID 40974179 · Full text
Arab adolescents are both racialized and invisible minorities in Canada and the United States (US), following the war on terror, incomplete ethnic categorization, Islamophobia, and anti-Arab racism. We conducted a scopin...
Arab adolescents are both racialized and invisible minorities in Canada and the United States (US), following the war on terror, incomplete ethnic categorization, Islamophobia, and anti-Arab racism. We conducted a scoping review of physical and psychological health in Arab adolescent populations living in the US and Canada. Inclusion criteria encompassed adolescents and emerging adults aged 10-24 who identified as Arab or having Arab identity and Southwest Asia and North Africa (SWANA) origins. Included scholarly literature reported at least one physical or psychological health outcome and was published in English or Arabic up until 2025. We identified over 200 relevant studies using PubMed, Web of Science, ResearchRabbit.ai, Google Scholar, and Undermind AI. We reviewed 50 total studies that met our inclusion criteria, highlighting the paucity of research on health and biopsychosocial variation among Arab adolescents in North America over a 30-year period. Despite heterogeneity in the health outcomes reported across studies, many focused on acculturative stress, ethnic identity formation, mental health, and discrimination. Few studies examined physical health and sexual and reproductive health; none examined pubertal, immunological, or linear growth outcomes. We discuss how biocultural and human biological research approaches can contribute to advancing a needed and more holistic understanding of health variation among Arab adolescent populations.
Comparing Physical Activity Levels and Metabolic Quotients to Quantify the Physical Activity Transition in Rwanda.
Harris AR, Yegian AK, Sibson BE … +10 more , Uwimana A, Niyibizi JB, Regnier D, Ojiambo RM, Nuhu A, Thomas A, Kocsis L, Vennemann T, Baggish AL, Lieberman DE
Am J Hum Biol · 2025 Sep · PMID 40970487 · Publisher ↗
OBJECTIVES: Although humans used to be physically active hunter-gatherers and subsistence farmers, there has been a recent and ongoing global physical activity transition as billions of people adopt industrial lifestyles...
OBJECTIVES: Although humans used to be physically active hunter-gatherers and subsistence farmers, there has been a recent and ongoing global physical activity transition as billions of people adopt industrial lifestyles primarily in urban areas. In order to analyze how to quantify the magnitude of this physical activity transition in a natural experiment, we compared two different metrics of physical activity metabolism among intensive subsistence farmers in northern Rwanda (Burera District, Northern Province) and urban professionals in the country's main city, Kigali. METHODS: We used the doubly labeled water (DLW) method to measure body composition, daily energy expenditure, and estimate activity energy expenditure in 36 individuals (n = 19 rural, n = 17 urban). We then used two metrics to compare activity energetics between the groups: Physical Activity Level (PAL), the ratio of total to resting energy expenditure, and Activity Metabolic Quotients (AMQ), a size-normalized measure of the daily metabolic demand from physical activity. RESULTS: While PALs suggest that Rwandan farmers are 1.5 times more active than urban office workers on average (PAL: 2.41 vs. 1.56), AMQs indicate that the rural farmers actually spend 2.6 times more energy on physical activity than urban office workers (AMQ: 1.85 ± 0.09 vs. 0.72 ± 0.05, p < 0.0001). CONCLUSIONS: Metrics based on total daily metabolism such as PAL and TMQ captured some of the differences in physical activity metabolism between the farmers and office workers but severely underestimated the magnitude of the difference as illustrated by AMQ. We find that rural Rwandan farmers have some of the highest physical activity metabolic rates ever measured in humans, emphasizing the magnitude of the physical activity transition and suggesting that subsistence farming can demand much higher energy expenditures compared not just to industrial lifestyles but also to hunting and gathering.
Micronutrient Deficiencies and Association With Hypertension: The Role of Folate, Vitamin B12, and Homocysteine.
Dahal S, Bhattacharjee D, Kaushik A … +8 more , Kasaudhan S, Saraswathy KN, Devi NK, Mitra RP, Pandey R, Dhamija RK, Krishan K, Chaudhary V
Am J Hum Biol · 2025 Sep · PMID 40960431 · Publisher ↗
OBJECTIVES: Folate and vitamin B12 are essential micronutrients involved in one-carbon metabolism. Deficiencies in these nutrients can elevate homocysteine levels, a recognized risk factor for hypertension. This study in...
OBJECTIVES: Folate and vitamin B12 are essential micronutrients involved in one-carbon metabolism. Deficiencies in these nutrients can elevate homocysteine levels, a recognized risk factor for hypertension. This study investigates the prevalence of folate and vitamin B12 deficiencies, hyperhomocysteinemia, and their association with hypertension in a North Indian population. METHODS: This cross-sectional study analyzed data from 1398 adult participants aged 30-75 years from rural Punjab, India. Biochemical parameters, including folate, vitamin B12, and homocysteine levels, were assessed using the Chemiluminescence Immunoassay technique. Hypertension was defined as SBP ≥ 140 mmHg and DBP ≥ 90 mmHg or the use of antihypertensive medication. RESULTS: The findings revealed a sizable prevalence of folate (26.4%) and vitamin B12 (30.7%) deficiencies, along with a high prevalence of hyperhomocysteinemia (64.8%). Homocysteine levels showed an inverse relationship with folate and vitamin B12 levels, though this association was evident only up to a specific threshold. Further, hyperhomocysteinemia was associated with prehypertension and hypertension, and low folate with prehypertension. Paradoxically, a positive correlation was observed between folate levels and blood pressure. CONCLUSIONS: These findings underscore the widespread prevalence of micronutrient deficiencies and hyperhomocysteinemia and their potential association with hypertension. The study also highlights the importance of establishing upper cutoff levels for folate and vitamin B12 to refine dietary and supplementation guidelines. The positive correlation between folate levels and blood pressure suggests potential interference with cellular nutrient uptake in hypertensive individuals, warranting further investigation.
Immunity Switches and Macrophage Manipulations: Trauma, Ovulation, and Depression as Latent Tuberculosis Reactivation Risks.
Burke S
Am J Hum Biol · 2025 Sep · PMID 40960002 · Publisher ↗
Inflammation is the immune system's natural response to initial tuberculosis infection. Tuberculosis bacteria have gained adaptations to manipulate the inflammatory process, sometimes settling into latency and containmen...
Inflammation is the immune system's natural response to initial tuberculosis infection. Tuberculosis bacteria have gained adaptations to manipulate the inflammatory process, sometimes settling into latency and containment in granulomas, ensuring their survival. Grounded in an evolutionary framework, this hypothesis-driven narrative synthesis centers upon immune-related switches, macrophage manipulations, and the critical roles of vascular endothelial growth factor A (VEGFA) in the body, exploring how this pro-inflammatory mitogen expressed by M1 macrophages frames risks for latent tuberculosis reactivation. The review focuses on trauma, ovulation, and depression, three case studies of pro-inflammatory switches creating risks for reactivation because of M1 macrophage polarization, the up-regulation of VEGFA expression, and angiogenesis (the sprouting of new blood vessels). A biological rationale is extended for why skeletal tuberculosis is so often connected with onsets in childhood, why adolescent and reproductive age females may experience heightened risks for latent tuberculosis reactivation relative to males, and why there is a potential for latent tuberculosis reactivation following onsets of depression. The immunity switches and reactivation risks of trauma, ovulation, and depression are problematic, particularly in contexts of endemic tuberculosis if large numbers of people are routinely latently infected, and among individuals with natural "high producer" VEGFA phenotypes, or those with strong type 1/M1/T1 or type 3/M1/T17 pro-inflammatory switch tendencies, and in infections with tuberculosis bacteria possessing macrophage- and granuloma-manipulating adaptations (virulence factors). Arguably, any disease or physiological state engaging pro-inflammatory switches (common and sometimes chronic in the modern population) and M1 macrophage polarizations, and any drug treatments or therapeutics intending to alter VEGFA expression should be considered for latent tuberculosis reactivation risk.
Biosocial Factors Shaping Perceptions of Disease Risk Among a Community-Based Sample of Sexual and Gender Minority People Living in Toronto During the COVID-19 Pandemic.
Gibb JK, Williams S, Mikelstiens K … +5 more , Charles J, McKinnon L, Beach L, McKerracher L, Fields J
Am J Hum Biol · 2025 Sep · PMID 40959967 · Full text
INTRODUCTION: The COVID-19 pandemic has disproportionately affected vulnerable populations, including sexual and gender minority (SGM) people. Food insecurity, prevalent among this population, may influence perceived vul...
INTRODUCTION: The COVID-19 pandemic has disproportionately affected vulnerable populations, including sexual and gender minority (SGM) people. Food insecurity, prevalent among this population, may influence perceived vulnerability to infection and related psychological outcomes. This study investigated the association between food insecurity and perceived vulnerability to infection among SGM adults in Toronto, Canada, during the third wave of the COVID-19 pandemic. METHODS: A mixed-methods study was conducted with 338 self-identified SGM adults recruited via respondent-driven sampling to complete an internet-based survey between March and July 2021. Measures included food security status, germ aversion, perceived infectability, and COVID-19 worry. Structural equation modeling (SEM) examined pathways linking food insecurity, discrimination, sleep quality, and perceived vulnerability to disease, adjusting for demographic and socioeconomic covariates. RESULTS: The SEM showed that discrimination predicted increased food insecurity (β = 0.30, p < 0.001) and poorer sleep quality (β = 0.26, p < 0.001). Sleep quality mediated the relationship between food insecurity and perceived vulnerability to disease (indirect effect = 0.16, p < 0.001). Discrimination had a significant total effect on perceived vulnerability to disease (β = 0.22, p < 0.001). DISCUSSION: These findings highlight the roles of food insecurity, discrimination, and sleep quality in shaping perceptions of disease vulnerability and risk among SGM people. Interventions addressing food security, mental health, and structural inequities are crucial for mitigating health disparities both during public health crises and in everyday life.
Is the Association Between Sports Participation in Childhood and Adolescence and Cardiometabolic Risk Mediated by Cardiorespiratory Fitness in Adulthood?
Batista MB, de Freitas MCM, Barbosa CCL … +6 more , Shigaki GB, Romanzini CLP, Venturini D, Okino AM, Barbosa DS, Ronque ERV
Am J Hum Biol · 2025 Sep · PMID 40956591 · Full text
OBJECTIVE: Analyze the direct and indirect associations between sports participation (SP) during childhood and adolescence and the metabolic risk profile in adulthood. Additionally, investigate whether the relationship i...
OBJECTIVE: Analyze the direct and indirect associations between sports participation (SP) during childhood and adolescence and the metabolic risk profile in adulthood. Additionally, investigate whether the relationship is mediated by current levels of cardiorespiratory fitness (CRF). METHODS: A retrospective observational study was conducted with 123 young adults (61 males), aged 18-25 years. Metabolic variables included body mass index (BMI), waist circumference (WC), relative body fat percentage (%BF), systolic blood pressure (SBP), diastolic blood pressure (DBP), and blood markers such as glucose levels, lipid profile, C-reactive protein, insulin, and the homeostatic model assessment of insulin resistance (HOMA-IR). A composite metabolic risk score was created by summing the z-scores. CRF was estimated using the 20-m shuttle run test. SP was assessed using a retrospective questionnaire, while moderate-to-vigorous physical activity (MVPA) in adulthood was measured using accelerometry. Structural equation modeling was applied to examine both direct and indirect associations. RESULTS: SP during childhood, adolescence, and both periods was indirectly and inversely associated with the metabolic risk score and HOMA-IR in adulthood. The effect of youth SP on metabolic risk was mediated by adult VO max related to metabolic score (β = -0.127; p < 0.001) and also to HOMA-IR (β = -0.067; p < 0.001). Moreover, MVPA positively interacted with VO max across all analytical models (p < 0.05). CONCLUSION: Youth SP during childhood and adolescence was indirectly associated with reduced metabolic risk in adulthood, with this relationship being mediated by current CRF. Additionally, the current practice of MVPA contributes positively to CRF in adulthood.
Exploring the Predictive Value of 2D:4D Ratio in Cardiovascular Diseases and Metabolic Syndrome: A Systematic Review.
Elvan Ö, Serin EK, Emül TG
Am J Hum Biol · 2025 Sep · PMID 40937919 · Publisher ↗
OBJECTIVE: The second-to-fourth digit (2D:4D) ratio, considered a proxy for prenatal androgen exposure, has been proposed as a potential biomarker for various adult health conditions, including metabolic syndrome (MetS)...
OBJECTIVE: The second-to-fourth digit (2D:4D) ratio, considered a proxy for prenatal androgen exposure, has been proposed as a potential biomarker for various adult health conditions, including metabolic syndrome (MetS) and cardiovascular diseases (CVDs). However, evidence supporting this association remains inconsistent. This systematic review aimed to synthesize current findings on the association between 2D:4D ratios and risk factors for MetS and CVD. METHODS: Nine peer-reviewed studies published between 2006 and 2025 were included, selected based on predefined PICOS criteria. Study populations consisted of adult males and females from diverse ethnic backgrounds. Evaluated risk factors included anthropometric measures (body mass index, waist circumference, neck circumference, waist-to-height ratio), metabolic indicators (blood pressure, glucose levels, lipid profiles), and established diagnostic criteria for MetS and CVD. Study designs and methodological quality were assessed to ensure comparability and rigor. RESULTS: Of the nine studies, three focused exclusively on females, five included both sexes, and one involved only males. Five studies addressed CVD risk, two investigated MetS, and two evaluated both. Seven studies reported statistically significant associations between lower 2D:4D ratios and increased cardiometabolic risk, particularly in males. Right-hand 2D:4D ratio measurements showed stronger predictive value. In contrast, two studies found no significant associations. CONCLUSION: While current evidence suggests a potential link between 2D:4D ratios, especially on the right hand, and cardiometabolic risk, inconsistencies remain. These findings highlight the need for further longitudinal and large-scale studies to determine the utility of the 2D:4D ratio as a noninvasive biomarker for MetS and CVD risk prediction.
Women's Health: Contributions From Human Biology.
Sievert LL
Am J Hum Biol · 2025 Sep · PMID 40926403 · Publisher ↗
The purpose of this review was to examine how human biologists have contributed to the field of women's health over the past 50 years. Prompted by the increasing international interest in gender equality during the 1970s...
The purpose of this review was to examine how human biologists have contributed to the field of women's health over the past 50 years. Prompted by the increasing international interest in gender equality during the 1970s and the beginning of the Human Biology Council in 1974, studies published in Human Biology (1974-1979) were reviewed for topical content. Based on the increasing national attention to the study of women's health and the inclusion of women in research during the 1990s, as well as the start of the American Journal of Human Biology in 1989, a topical review was carried out for articles published in the AJHB (1989-1995). Current topics in women's health, targeting the past decade, were organized in relation to biocultural perspectives, evolutionary approaches (life history and evolutionary medicine), and the Developmental Origins of Health and Disease. Central questions include whether the contributions of human biologists reflect changing levels of political interest in women's health across time, which topics remained the same across the 50 years, and which topics were added. Topics that held steady across time include pregnancy and lactation, bone mineral density, and blood pressure. Among the changes over time, girls and women were more likely to be included in research, studies of pregnancy were more likely to include maternal health, studies of nutrition became more common, and human biologists expanded their repertoire of explicit theoretical perspectives. Finally, this review ends with worries about the future.
Remote Blood Collection for Telomere Length Measurement: Assessing the Impact of Sample Characteristics and Handling on DNA Quality and Assay Outcomes.
Conklin QA, Smith DL, Dai G … +3 more , King BG, Saron CD, Lin J
Am J Hum Biol · 2025 Sep · PMID 40913436 · Full text
BACKGROUND: Telomere length (TL) is a valuable marker of aging and stress that reflects both genetic and environmental influences. Quantitative PCR (qPCR) TL measurement is a powerful and cost-effective assay, especially...
BACKGROUND: Telomere length (TL) is a valuable marker of aging and stress that reflects both genetic and environmental influences. Quantitative PCR (qPCR) TL measurement is a powerful and cost-effective assay, especially in population studies with limited quantities of source material. Nevertheless, collecting and transporting high-quality blood samples can be logistically challenging, and research suggests that several preanalytical and analytical factors can influence the reliability and precision of the qPCR assay. Here we describe a procedure for collecting blood remotely in a large-scale study. We then assess the influence of various features of the samples, as well as their collection, transportation, and storage on DNA quality and TL assay outcomes. METHOD: Participants used at-home collection kits to collect a few drops of whole blood in BD Microtainers during a baseline (n = 265) and 1-year follow-up (n = 178) assessment. DNA was extracted using a magnetic-bead method, and DNA yield, purity, and integrity were assessed. TL was measured using qPCR. To assess inter-assay variation, the coefficient of variation (CV) was calculated across repeated TL measurements (three runs) for each sample. When there was adequate material for duplicate extractions of DNA from the same blood samples, we calculated the intra-class correlation (ICC) of the resultant TL values to assess assay precision. RESULTS: Our analyses revealed that as little as 50 μL of blood yielded sufficient DNA for highly precise TL measurement (ICC = 0.962, n = 365). Transportation time and an additional year of storage time at -80°C did not meaningfully affect DNA quality or assay outcomes. However, blood clotting was associated with longer telomere estimates, whereas greater temperature exposure was related to shorter telomere estimates. CONCLUSIONS: We established that whole blood collected remotely in BD Microtainers can provide a valid sample source for qPCR TL measurement. We also outline important logistical considerations related to sample collection and handling and provide recommendations for researchers who want to use this method.
Exploring Risk Factors and Predictive Modeling of Child Malnutrition in Pakistan Using Machine Learning.
Saleem MU, Aslam MU, Khatir AG … +1 more , Jiang Q
Am J Hum Biol · 2025 Sep · PMID 40908657 · Publisher ↗
OBJECTIVE: This study aims to identify risk factors and develop predictive models of child malnutrition (stunting, wasting, and underweight) in Pakistani children under five using machine learning approaches. STUDY DESIG...
OBJECTIVE: This study aims to identify risk factors and develop predictive models of child malnutrition (stunting, wasting, and underweight) in Pakistani children under five using machine learning approaches. STUDY DESIGN: This cross-sectional design utilized data from the Pakistan Demographic and Health Survey 2017-2018 (PDHS). METHODS: Logistic regression was employed to identify significant socio-demographic and health-related risk factors. Four machine learning models-Random Forest (RF), Support Vector Machine (SVM), Naïve Bayes (NB), and AdaBoost-were applied to predict malnutrition indicators, with performance evaluated based on accuracy, sensitivity, specificity, and F-measure using a two-stage validation strategy (10-fold cross-validation and 80:20 train-test split). RESULTS: Key risk factors identified included consanguineous marriages, lower wealth status, low maternal education, and geographic disparities in Sindh and Baluchistan. Among the machine learning models, Random Forest demonstrated the highest overall accuracy and specificity across all indicators, while SVM showed higher sensitivity for wasted and underweight children. CONCLUSION: The study highlights the complex interplay of socio-demographic factors in child malnutrition and the potential of machine learning models to effectively predict these conditions, underscoring the need for targeted interventions focusing on maternal education, access to clean water and sanitation, and poverty alleviation, particularly in high-risk regions.
Genetic and Environmental Contributions to Child Height in Low- and Middle-Income Countries.
Dewau R, Byrne S, Hyppönen E … +2 more , Lee SH, Benyamin B
Am J Hum Biol · 2025 Sep · PMID 40899384 · Full text
BACKGROUND: Child height is influenced by genetic and environmental factors. However, it is unclear how these factors vary by geographical region and by study design, particularly in low- and middle-income countries (LMI...
BACKGROUND: Child height is influenced by genetic and environmental factors. However, it is unclear how these factors vary by geographical region and by study design, particularly in low- and middle-income countries (LMIC), where data is scarce. Understanding these variations will aid the identification of factors that may be hindering growth in specific populations. METHODS: We analyzed height data of children under 5 years of age from 17 066 twin pairs and 2 024 672 parent-offspring pairs using the Demographic and Health Surveys conducted in 69 countries. We estimated genetic and environmental contributions to child height using a mixture distribution model for twins to account for unknown zygosity and a parent-offspring regression for singletons. A mixture distribution model assumes that the sample comprises a mixture of monozygotic and dizygotic twins and estimates heritability based on the distribution of phenotypic similarity across twin pairs, without requiring prior classification of zygosity. RESULTS: Twin studies consistently estimated heritability at 0.35 (95% CI, 0.34-0.37) across all regions. The estimated proportion of phenotypic variance attributable to shared environmental factors was 0.63 (95% CI, 0.62-0.63), while the contribution of unique environmental factors was 0.02 (95% CI, 0.02-0.02). Conversely, there was variation in the heritability estimates from parent-offspring studies, ranging from 0.27 (95% CI, 0.26-0.30) in North Africa, West Asia and Europe to 0.47 (95% CI, 0.46-0.48) in Latin America and Caribbean. CONCLUSION: The observed discrepancies between twin and family study estimates underscore the complex interplay between genetic and environmental factors. These variations suggest that environmental factors play a critical role in determining height outcomes during childhood. Further research is needed to explore these environmental factors in greater detail with the aim of developing region-specific interventions to address height disparities, particularly in underprivileged regions.
Conducting Scoping and Systematic Reviews With a Focus on Biocultural Research: The SCRIBE Toolkit.
Varela-Silva MI, Rush N, Pearson N
Am J Hum Biol · 2025 Sep · PMID 40891166 · Full text
The SCRIBE (SystematiC Reviews In Biocultural rEsearch) toolkit offers a structured approach for conducting scoping and systematic reviews in biocultural research. It addresses the challenges of synthesizing information,...
The SCRIBE (SystematiC Reviews In Biocultural rEsearch) toolkit offers a structured approach for conducting scoping and systematic reviews in biocultural research. It addresses the challenges of synthesizing information, aggregating diverse data, and conducting robust analyses in this field. Biocultural research is vital to anthropology, public health, community health, and policy, as it reveals biological and cultural determinants of health and disparities globally. However, systematic reviews often exclude biocultural factors, leading to biased evidence that overlooks Indigenous, ethnic minority, and small-scale populations. To fill this gap, the SCRIBE toolkit guides researchers in integrating biocultural frameworks into review methodologies. Developed from a comprehensive literature review and a survey of leading journals (2019-2025), it responds to the underuse of biocultural perspectives in formal reviews. The SCRIBE toolkit is composed of six sequential steps: (i) decide on the type of review, (ii) select a suitable framework (e.g., PICOS, PEO, SPIDER, PCC), (iii) develop the search protocol, (iv) title/abstract screening and full-text reading, (v) data extraction, risk of bias, and meta-analysis, (vi) finalize the review. It can be implemented using accessible platforms like Notion and Trello to enhance usability and collaboration or used as a Word file. By mapping biocultural variables into an operational framework and aligning them with established review protocols, the SCRIBE toolkit promotes interdisciplinary, context-sensitive, and equitable research synthesis. It bridges methodological gaps between anthropology, public health, and evidence-based practice, supporting the inclusion of marginalized populations and complex cultural contexts. SCRIBE serves as both a practical tool and a call to broaden the epistemological and methodological boundaries of review science within human biology and related fields.
Twenty Years Later: Growth Rates and Life Histories in Twenty-Two Small-Scale Societies.
Kramer KL
Am J Hum Biol · 2025 Sep · PMID 40888370 · Publisher ↗
This commentary on Growth Rates and Life Histories in Twenty-Two Small-Scale Societies overviews the original publication and its contributions, and reviews advances in the field of human growth and development since its...
This commentary on Growth Rates and Life Histories in Twenty-Two Small-Scale Societies overviews the original publication and its contributions, and reviews advances in the field of human growth and development since its publication.
Body Composition and Geographical Altitude in Newborns From the Province of Jujuy (Argentina).
Martínez JI, Figueroa MI, Andrade LD … +2 more , Grandi C, Dipierri JE
Am J Hum Biol · 2025 Sep · PMID 40888145 · Publisher ↗
AIM: Knowledge of neonatal body composition in high-altitude populations is insufficient. To estimate Fat Mass (FM), Fat Free Mass (FFM), and Body Fat percentage (BF%) in Jujuy newborns (NB) using the weight/length (W/L)...
AIM: Knowledge of neonatal body composition in high-altitude populations is insufficient. To estimate Fat Mass (FM), Fat Free Mass (FFM), and Body Fat percentage (BF%) in Jujuy newborns (NB) using the weight/length (W/L) ratio and its relationship with maternal, fetal, and environmental characteristics. METHOD: Data were obtained from 47 598 mother/child pairs recorded in the Jujuy Perinatal Information System (SIP) between 2009 and 2014, including NB and maternal weight, length/height, gestational and maternal age, educational, nutritional, and marital status; birth interval; maternal surname, and planned pregnancy. The prevalence of unsatisfied basic needs (% UBN) was determined based on the mother's place of residence. The data were divided into two groups: highlands (HL > 2500 masl) and lowlands (LL < 2500 masl). W/L, FM, FFM, and BF% centiles were calculated using GAMLSS LMS in R and compared with INTERGROWTH-21st. ANOVA and Chi-squared tests were applied as needed. Statistical associations between the response variables FM, FFM, and BF% and maternal and environmental variables were tested using GAMM. RESULTS: FM and BF% were significantly higher in females and in LL, while the opposite was true for FFM. The three indicators differed according to maternal nutritional status and age, parity, pregnancy planning, prematurity, birth size, geographical altitude, surnames, and UBN. GAMM showed that gestational age, sex, birth size, UBN, and surnames are associated with FM, FFM, and BF% at both altitudinal levels. CONCLUSIONS: The body composition of Jujuy NB varies with geographical altitude, NB characteristics, ethnicity, and socioeconomic conditions.
Early Pregnancy in Times of Climate Change: First-Trimester Heat Exposure Is Associated With Reduction in Fetal Crown-Rump Length in the 12th/13th Week of Gestation-A Retrospective Study From Vienna, Austria.
Nindl S, Hartmann B, Fellner J … +1 more , Kirchengast S
Am J Hum Biol · 2025 Jul · PMID 40878881 · Full text
OBJECTIVES: This study focused on the association between fetal crown-rump length (CRL) in the 12th/13th gestational week and the number of 1st trimester heat days to assess the impact of rising temperature on intrauteri...
OBJECTIVES: This study focused on the association between fetal crown-rump length (CRL) in the 12th/13th gestational week and the number of 1st trimester heat days to assess the impact of rising temperature on intrauterine growth in early pregnancy. METHODS: This single-center medical record-based study comprises 10 085 singleton live births (n = 5228; n = 4857) taking place in Vienna, Austria between 2011 and 2019. The sonographic determination of CRL took place routinely during the 12th or 13th gestational week. Linear regression analyses with CRL as the dependent variable and the number of 1st trimester heat days controlled for maternal parameters and the gestational week of CRL measurement were computed for the entire sample and separately by sex. RESULTS: CRL decreased significantly (p < 0.001) by 0,015 mm on average per heat day in the 1st trimester. Among male fetuses, CRL decreased significantly (p < 0.001) by 0,021 mm, while among female fetuses, only an insignificant decrease was observed. CONCLUSION: Heat days during the 1st trimester could have a small adverse effect on early fetal growth.
Age-Varying Patterns of Total Cholesterol by Modifiable Lifestyle Factors Across Mid to Late Adulthood: Applying Time-Varying Effect Modeling.
Song J, Kim H, Lee S … +2 more , Keller JL, Jung M
Am J Hum Biol · 2025 Sep · PMID 40884305 · Publisher ↗
OBJECTIVES: Total cholesterol is a risk factor for cardiovascular disease, yet little is known about how its age-related trajectory differs by lifestyle factors across adulthood. METHODS: We analyzed data from 8758 adult...
OBJECTIVES: Total cholesterol is a risk factor for cardiovascular disease, yet little is known about how its age-related trajectory differs by lifestyle factors across adulthood. METHODS: We analyzed data from 8758 adults aged 40-80 years using NHANES from 2011 to 2020. Total cholesterol was measured via enzymatic analysis of serum samples. Physical activity was assessed using the Global Physical Activity Questionnaire, with participants classified as meeting or not meeting physical activity guidelines (≥ 150 min/week of moderate-to-vigorous activity). Weight status was determined by body mass index (BMI), categorized as healthy BMI (18.5-24.9 kg/m) or overweight BMI (≥ 25.0 kg/m). Time-varying effect modeling (TVEM) was used to estimate total cholesterol across age, stratified by physical activity and BMI category. RESULTS: TVEM indicated that there were no significant differences in total cholesterol levels between physical activity groups across age. In contrast, individuals with an overweight BMI had higher total cholesterol levels than those with a normal BMI, with significant differences observed between ages 63 and 69. CONCLUSIONS: These findings highlight late midlife as a turning point when excess body weight may exert a stronger influence on cholesterol regulation. Age-specific approaches to weight management may enhance cardiovascular disease prevention efforts.
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