American Journal of Human Biology最新文献

Objective: Handgrip strength (HGS) provides a dynamic indicator of overall strength and physical fitness. Population-based investigations of anemia and iron deficiency as predictors of HGS are limited; most studies rely on elderly and/or clinical samples. We assessed iron deficiency, anemia, body mass index (BMI), and body fat percentage as predictors of HGS among a representative cross-sectional sample of adult residents of Matlab, Bangladesh.

Methods: We collected HGS, anthropometric measurements, and whole blood specimens from a representative, population-based sample of adults in Matlab. We used hemoglobin to identify anemia and soluble transferrin receptor to identify iron deficiency. We estimated mixed-effects generalized linear models of HGS.

Results: Iron deficiency, but not anemia, was negatively associated with HGS among both men and women. Among men, but not women, underweight BMI was negatively associated with HGS, and overweight BMI was positively associated with HGS.

Conclusions: Iron nutrition is important for muscles' capacity for work and overall physical fitness, regardless of the presence of anemia. Among men (but not women) in this setting, BMI categories seem to capture differences in muscle tissue as well as adiposity.

Objective: This study aims to investigate the relationship between polygyny and the number of children ever born (CEB), as well as the moderating effects of education on this relationship in the context of Afghanistan. Additionally, decomposition analysis of the marginal effect will be utilized to identify the factors that influence the likelihood of having a certain number of children.

Methods: A zero-inflated negative binomial (ZINB) regression model and marginal effect analysis were applied to the 2015 Afghanistan Demographic and Health Survey (AfDHS) with a sample (n = 29 461 women aged 15-49). CEB measured the number of children born to each woman; polygyny was assessed based on whether women were in polygynous or monogamous unions. All analyses were performed using STATA version 18.1.

Results: About 7% of the sample were in polygynous marriages, and the average number of children ever born (CEB) was 4.18. The ZINB model indicates that polygynous women had a 12% lower likelihood of higher CEB; when education was included as a moderator, this reduction increased to 13%. The marginal effects further show that polygynous women had, on average, 0.54 fewer children than monogamous women. Education also demonstrated a protective effect: primary education was associated with 0.17 fewer children, while higher education reduced the number of children by 0.58.

Conclusion: This study indicates that decreases in CEB among women in both polygynous and monogamous unions are linked to higher levels of women's education and delayed marriage. The study concludes that increasing access to family planning and promoting women's education may reduce the disparities in CEB between polygyny and monogamy in Afghanistan.

Objectives: The present study evaluates the effects and interaction of skin pigmentation, sun exposure, and genetics on 25(OH)D₃ levels among ostensibly healthy Indians.

Methods: Vitamin D₃ was estimated (N = 427) and means were compared between the sexes and study populations. Vitamin D₃ was correlated with Melanin Index (MI) and Weekly Sun Exposure Scores (WSES) using Kendall's tau-b (τb). The effect of age, sex, MI, WSES, and 12 SNPs from vitamin D and skin pigmentation genes were tested on 25(OH)D₃ levels using univariate and multivariate linear models.

Results: A total of 76.6% of the sample were deficient, with males being more deficient than females (p = 0.0016). Deshastha Brahmin caste with lowest MI (42.91 ± 4.47) and WSES (14.4 ± 8.55) reported highest 25(OH)D₃ levels (26.09 ng/mL±16.84). Tribals with higher MI (52.83 ± 7.84-58.83 ± 6.37) and WSES (21.96 ± 7.85-28 ± 0) report low 25(OH)D₃ levels (13.31 ± 7.05-17.94 ± 972). Vitamin D₃ was weakly correlated with MI in Bhils and Kokanas (p < 0.05) and was not significantly correlated with WSES. Multivariate regression shows only sex (p = 0.031), MI (p = 0.018), and WSES (p < 0.001) to be significant predictors of vitamin D levels as compared to age, population, and rs1426654 genotype.

Conclusion: Vitamin D levels vary significantly among populations with widespread deficiency seen in tribal and rural populations, suggesting population-specific environments and behavioral factors to be at play. Targeted dietary fortification is needed, and additional large-scale longitudinal and genome-wide association studies will help identify key factors responsible for vitamin D deficiency among Indian populations.

Assam serves as a melting pot where various ethnicities converge, shaped by its strategic location bordering the six northeastern states and neighboring countries. This study examines the genomic ancestry of Indo-Aryan speakers in Assam, a region at the eastern edge of the Indian subcontinent known for its diverse linguistic and cultural influences. Principal Components Analysis (PCA) revealed that Assamese Indo-Aryans cluster closely with Bangladeshi Indo-Aryans, diverging from the typical South Asian genetic continuum. This group shows significant ancestral influences from East and Southeast Asia. Outgroup f3 statistics indicated that Assamese Indo-Aryans exhibit greater genetic drift in relation to other Indo-Aryan populations, particularly the Harijan and Kol groups from the Ganga plain, rather than with geographically closer Bengali or Nyishi populations. Haplotype-based fine-structure and identity by descent (IBD) analyses confirmed a close genetic affinity with Bangladeshi Indo-Aryans, along with notable connections to Harijan and Kol populations. The low levels of Runs of Homozygosity (RoH) suggest a high degree of genetic diversity, most likely due to a result of admixture and a large effective population size. Admixture events are estimated to have occurred 55 to 61 generations ago, indicating a composition of 76% Indian ancestry and 24% East/Southeast Asian ancestry. These findings, with enhanced resolution, suggest a reconsideration of the previous assumption that Northeast India served as a genetic barrier. Instead, they appear to support its role as a corridor facilitating bidirectional gene flow between South and East/Southeast Asia. Furthermore, the coexistence of diverse linguistic affiliations of ethnic groups in this region reflects in their ancestry patterns. These findings highlight the complex interplay of geography, language, and genetic exchange in the region.

Objectives: To test whether the universal two-parameter DS model, originally proposed in 2015, can accurately describe how human brain and body mass change from conception to old age and reproduce their complex allometric relationship.

Methods: We analyzed published autopsy data on brain and body mass from conception to ~90 years, encompassing both sexes. Using nonlinear least-squares regression in Maple, we fitted the DS model to the data, testing single- and two-stage growth scenarios. Model performance was evaluated via residual analysis.

Results: A two-stage model-with a transition at ~1.5 years post-conception-accurately described both brain and body mass trajectories (typically within 10% error). The model successfully reproduced the non-monotonic, "hook-shaped" allometric curve of brain vs. body mass, including age-related declines after ~45 years. Furthermore, rescaling age using development time (derived from the DS model) largely eliminated sex differences in body mass trajectories and equalized male and female life expectancy in biological time.

Conclusions: The DS model provides a parsimonious, scientifically well-grounded framework for human ontogenetic growth. It identifies ~1.5 years post-conception as a critical developmental transition and offers a physiologically meaningful time metric with potential applications in theoretical biology, evolutionary anthropology, biogerontology, etc.

Background and aims: Accurate measurement of total energy expenditure (TEE) is critical for maintaining energy balance and body weight. This study aimed to analyze differences in TEE assessed by the doubly labeled water method (DLW-TEE), using food quotient (FQ) derived from self-reported 24-h dietary recalls, respiratory quotient measured by indirect calorimetry (RQ-IC), and usual respiratory quotient of 0.85 (RQ-0.85) based on Western-type diet intakes.

Methods: Secondary analysis from a cross-sectional study conducted in a sample of 41 independent (21 women) older people (≥ 60 years). FQ was obtained from three self-reported 24-h dietary recalls, RQ-IC was measured after an overnight fast under resting conditions. Repeated measures analysis of variance was used to compare differences in DLW-TEE calculated with FQ, RQ-IC, and RQ-0.85.

Results: DLW-TEE was significantly different between the three approaches (p = 0.025). The RQ approaches on DLW-TEE did not differ significantly between sexes (p = 0.325). The overall mean DLW-TEE RQ-0.85 was 2253 (SD = 529, 95% CI: 2086, 2420) kcal/day, DLW-TEE RQ-IC was 2251 (SD = 541, 95% CI 2090, 2431) kcal/day, and DLW-TEE FQ was 2208 (SD = 534, 95% CI 2039, 2376). DLW-TEE calculated with FQ significantly reduced TEE compared to the mean DLW-TEE with RQ-0.85 values (ΔTEE -45 kcal/day, p < 0.001).

Conclusion: Self-reported dietary intake data may provide a more context-specific estimate of the FQ than relying solely on RQ from indirect calorimetry or the fixed RQ of 0.85 in DLW-based TEE calculations. Although the resulting differences in TEE are modest, they can lead to overestimation of energy requirements over time.

Excess weight is a global public health issue related to the accumulation of body fat and can be caused by various factors. This study aimed to determine the prevalence and associated factors of excess weight among adults living in a coastal area of the Brazilian Amazon. Methods. This cross-sectional study included 407 adults residing in Bragança, Pará, northern Brazil. Socioeconomic, demographic, behavioral, and morbidity data were analyzed using Poisson regression to identify potential associations with excess weight. The prevalence of excess weight was 63.3%. Behavioral factors directly associated with excess weight included avoiding raw salads and boiled eggs. The outcome was associated with factors related to morbidity, such as hypertension and diabetes mellitus. However, walking to work was found to be a protective factor against excessive weight. The high prevalence of excess weight detected in this coastal Amazon region indicates a desire to prioritize this issue in local public health agendas. Implementing individual and community-based interventions can help reduce health risks and improve the population's quality of life.