American Journal Of Human Biology[JOURNAL]
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200 papers
Can We Generalize About the Mortality Features of the 1918-19 Influenza Pandemic? An Examination of a Small-Scale and Isolated British Columbian Population.
Tripp L, Barber R, Boorman C
Am J Hum Biol · 2026 Jun · PMID 42216893 · Publisher ↗
OBJECTIVES: In this paper we use the small-scale population of the Fort George area (located in the central interior of British Columbia, Canada) to test the applicability of the three signature mortality features of the...
OBJECTIVES: In this paper we use the small-scale population of the Fort George area (located in the central interior of British Columbia, Canada) to test the applicability of the three signature mortality features of the 1918/19 influenza pandemic: mortality rates higher than those in preceding influenza epidemics except for the elderly; rapidly recurring waves; and W-shaped age mortality distribution. MATERIALS AND METHODS: Death records from the British Columbia Archives and the University of Northern British Columbia's Geoffrey R. Weller Library and Northern BC Archives Learning Resource on 1918 influenza in Prince George (which included the Corless Funeral ledger, the Prince George Citizen, and a Record of Confinements journal) were used to assess the presence of the signature features. Analyses were conducted on monthly influenza death rates for the duration of the influenza pandemic, from September 1918 until December 1920, and on age and sex-specific influenza rates. RESULTS: The Fort George area escaped a herald wave in the spring/summer of 1918, and the overall influenza death rate was 14.17 per 1000 living. The first wave, in the fall, peaked in the month of October at a rate of 5.24 per 1000 living. The male influenza death rate was 12.46 per 1000 living, and the female rate was higher, at 16.37 per 1000 living, but the rates were not significantly different (Z = -1.34; p = 0.180). The peak influenza death rate occurred in those 65 years or older. DISCUSSION: We confirmed that two of the three mortality features were observed in Fort George. We could not assess whether the 1918/19 influenza pandemic had higher mortality rates relative to previous pandemics; however, the influenza death rate in the elderly was high, which indicates that older individuals were not exposed to the earlier influenza pandemics in the 19th century. The W-shape distribution of influenza death rates, coupled with narrative accounts, provides support for evidence that both single men and young families were negatively impacted by the pandemic.
Physiological Responses to Occupational Heat Exposure Among Male Agricultural and Brick-Field Workers in Eastern India: A Biochemical Perspective.
Nath A, Chakraborty D, Sahu S
Am J Hum Biol · 2026 Jun · PMID 42214031 · Publisher ↗
Occupational heat exposure is considered a major health concern for workers performing strenuous work during hot environmental conditions. This cross-sectional study aimed to assess the biochemical and physiological resp...
Occupational heat exposure is considered a major health concern for workers performing strenuous work during hot environmental conditions. This cross-sectional study aimed to assess the biochemical and physiological responses to occupational heat exposure among agricultural and brick-field workers working in hot environmental conditions in eastern India. A sub-sample of 20 agricultural workers and 20 brick-field workers was selected from the larger sample of 200 workers each to assess the physiological and biochemical responses to hot environmental conditions during the summer and winter seasons. Environmental heat exposure was measured using the time-weighted average Wet Bulb Globe Temperature (TWA-WBGT in °C). Venous blood samples were collected to measure the levels of sodium, potassium, and aldosterone. Active sweat gland responses were measured using the modified starch-iodine technique. Multivariate general linear models of repeated measures were used to measure the effect of the following factors: season, exposure day, and occupation. The multivariate analysis showed significant seasonal effects on serum potassium, sodium, and aldosterone levels, and that exposure day influenced only potassium, not occupation. The monitoring sessions showed normal physiological levels of electrolytes in both occupational groups. Sweat gland activation was also significantly higher during the summer season. TWA-WBGT values above 23°C-25°C are associated with a higher probability of hyponatremia, as revealed by the receiver operating characteristic (ROC) analysis. These findings highlight the physiological adjustments associated with occupational heat exposure and emphasize the importance of hydration and heat mitigation strategies for outdoor workers.
Response to the Letter to the Editor.
Gür M, Akkoc RF, Oz B … +2 more , Karatas A, Koca SS
Am J Hum Biol · 2026 Jun · PMID 42206778 · Publisher ↗
Abstract loading — click title to view on PubMed.
Sexual Dimorphism in Facial and Body Shape and Their Relationship in Modern Humans of African, Asian, and European Descent.
Butovskaya ML, Rostovtseva VV, Dronova DA … +12 more , Mezentseva AA, Semenova OV, Komarova AV, Sizov YO, Mabulla A, Kavina A, Mazengo F, Dashieva NB, Struchkova NA, Matsakova NP, Korotkova AA, Butovsky RO
Am J Hum Biol · 2026 Jun · PMID 42206769 · Publisher ↗
OBJECTIVES: Our study aimed to quantify the degrees of sexual dimorphism in facial shape and nineteen body parameters across eleven living populations from three major world regions: Sub-Saharan Africa (five populations)...
OBJECTIVES: Our study aimed to quantify the degrees of sexual dimorphism in facial shape and nineteen body parameters across eleven living populations from three major world regions: Sub-Saharan Africa (five populations), Europe (three populations), and Asia (three populations). METHODS: The data were collected in Tanzania and Russian Federation (N = 2214 individuals, aged 16-35 years), utilizing identical methods. Facial shape was explored through geometric morphometrics based on photographs. Body parameters were obtained through direct measurements. RESULTS: We found that body parameters are highly sexually dimorphic in humans and have population specificity: in taller and more robust populations (Europeans, Asians), body height, bone mass, handgrip strength, and wrist diameter are the most dimorphic traits, whereas Africans demonstrate the highest variability in body dimorphism. In contrast, the degree of facial sexual dimorphism increases from minimum in Africans to intermediate in Asians and maximum in European populations. Sexually dimorphic facial shape patterns vary by population origin, with allometry on average explaining over half of the sex differences. We did not find a linear relationship between overall degrees of body and facial dimorphism across study populations. However, dimorphism in several isolated body parameters correlated with facial dimorphism at the population level. Particularly, for body height, handgrip strength, and bone mass, such correlations remained evident even after correction for population phylogenetic relatedness. CONCLUSIONS: Differences in degrees of sexual dimorphism in study populations cannot be explained by allometry alone, but rather they result from a complex interplay of various factors and pressures, including phylogenetic origin, environmental conditions, and cultural norms.
Comparative Evaluation of Demirjian and Willems Methods for Dental Age Estimation in 7- to 12-Year-Old Children: A Cross-Sectional Study.
Gharavi M, Afzalsoltani S, Varazghan ZS
Am J Hum Biol · 2026 Jun · PMID 42206745 · Publisher ↗
OBJECTIVE: Dental age estimation is vital in clinical and forensic dentistry. This study compared the accuracy of the Willems and Demirjian methods in estimating dental age among children aged 7-12 years in Alborz Provin...
OBJECTIVE: Dental age estimation is vital in clinical and forensic dentistry. This study compared the accuracy of the Willems and Demirjian methods in estimating dental age among children aged 7-12 years in Alborz Province, Iran. MATERIALS AND METHODS: In this cross-sectional analytical study, 50 panoramic radiographs from 32 girls and 18 boys aged 7-12 years were analyzed. Chronological age was calculated using birth and radiograph dates. Dental age was estimated using the Willems and Demirjian methods. Statistical analysis, including paired t-tests, ANOVA, and Pearson correlation, was conducted using SPSS version 25. RESULTS: The Willems method overestimated age by an average of 0.09 years (0.16 for boys, 0.05 for girls), while the Demirjian method overestimated by 0.44 years (0.26 for boys, 0.55 for girls). The smallest discrepancy was observed in boys aged 9-10 years (0.067 years), and the largest in girls aged 11-12 years (1.2 years). However, this finding should be interpreted with caution due to the small sample size in this age group (n = 7). CONCLUSION: Both methods showed a strong correlation with chronological age. The Willems method tended to produce estimates closer to chronological age than the Demirjian method in this sample. However, these findings should be interpreted with caution due to the relatively small sample size in several age groups.
Interindividual Variation in Adult Gut Microbiome Composition in Two Rural Communities in Japan: Associations With Energy and Nutrient Intakes.
Sekiya S, Masuda M, Mizuno Y … +4 more , Naka H, Goto C, Imai H, Umezaki M
Am J Hum Biol · 2026 May · PMID 42165387 · Publisher ↗
OBJECTIVES: The "Japanese diet" has long been regarded as a key factor contributing to the remarkable life expectancy of the Japanese population. Given that the gut microbiome is thought to mediate the link between diet...
OBJECTIVES: The "Japanese diet" has long been regarded as a key factor contributing to the remarkable life expectancy of the Japanese population. Given that the gut microbiome is thought to mediate the link between diet and health, this study investigated energy and nutrient intake among rural populations in Japan, who are presumed to adhere closely to the traditional "Japanese diet," and examined their association with gut microbiome diversity and composition. METHODS: A cross-sectional study of 263 individuals aged ≥ 20 years was conducted in two rural communities in Japan, in July and August 2022. Participants completed a food frequency questionnaire, and we measured weight and height and collected fecal samples. The diversity and composition of the gut microbiome were assessed using 16S ribosomal RNA analysis. The associations between energy and nutrient intakes and alpha diversity metrics, beta diversity metrics, and the relative abundance of bacteria at the genus level were assessed. RESULTS: Individuals who consumed more nutrients characteristic of seafood, rice, and vegetables (vitamin D, omega-3 highly unsaturated fatty acids, carbohydrates, total dietary fiber, and insoluble dietary fiber) had significantly higher gut microbiome diversity, while those who consumed more alcohol and fat had significantly lower microbiome diversity. Energy intake from alcohol, as well as intakes of cholesterol, iron, vitamin B1, vitamin C, carbohydrates, soluble dietary fiber, omega-3 highly unsaturated fatty acids, and calcium were significantly associated with beta diversity metrics (p < 0.05), indicating that gut microbiome composition varied with these nutrient intakes. CONCLUSION: Nutrient intakes may influence the interindividual variation in the gut microbiome seen in two rural populations in Japan. Future research should focus on elucidating the interactive effects between the "Japanese diet" and the gut microbiome.
Regarding "The 2D:4D Digit Ratio and Primary Sjögren's Syndrome: A Window Into Prenatal Hormonal Influences on Exocrine Autoimmunity".
Malik MMUD
Am J Hum Biol · 2026 May · PMID 42163517 · Publisher ↗
Abstract loading — click title to view on PubMed.
Climate Matters-Association Between Ambient Temperature During Pregnancy and Birth Length in Austria Between 1984 and 2014-A Population-Based Study.
Waldhoer T, Kirchengast S, Yang L
Am J Hum Biol · 2026 May · PMID 42162582 · Publisher ↗
OBJECTIVES: The impact of ambient temperature on fetal growth was tested using a data set of 1 208 491 singleton births taking place in Austria between 1984 and 2014. It was hypothesized that higher ambient temperature d...
OBJECTIVES: The impact of ambient temperature on fetal growth was tested using a data set of 1 208 491 singleton births taking place in Austria between 1984 and 2014. It was hypothesized that higher ambient temperature during pregnancy would be associated with shorter birth length. METHODS: Daily ambient temperature data spanning 1983 to 2014 from 39 Austrian districts were retrieved and used for analysis. A Dynamic-Lag-Non-linear (DLNM) model was then fitted to link birth length with the time course of ambient temperature during each pregnancy. This model was adjusted for the following variables: maternal education level, maternal age, newborn sex, gestational age, newborn year of birth, maternal parity, and citizenship. RESULTS: The effect of temperature on birth length was observed to be negative immediately following conception up to approximately gestational week 9 and again from about gestational week 15 toward the end of pregnancy. In contrast, during gestational weeks 10 to 14, there was no apparent association between temperature and birth length. The effect of hypothetically shifting a randomly drawn newborn's original birth date forward from January to October is associated with a decrease in predicted birth length by about 0.8 mm. CONCLUSION: Higher temperatures during early pregnancy and from the 15th gestational week onwards appear to have a negative effect on the fetal growth process.
The Geographical Distribution of Lactose Tolerance-Associated Alleles 13910*T and 13915*G Is Strongly Linked to Male Founder Events in Eurasia.
Grasgruber P
Am J Hum Biol · 2026 May · PMID 42159257 · Publisher ↗
Lactose tolerance (lactase persistence) represents a very progressive human adaptation, the origins of which remain incompletely understood. This study aims to examine the geographical distribution of the two alleles ass...
Lactose tolerance (lactase persistence) represents a very progressive human adaptation, the origins of which remain incompletely understood. This study aims to examine the geographical distribution of the two alleles associated with lactose tolerance in Eurasia (13910*T and 13915*G) in relation to the main Y haplogroups and autosomal ancestry components. Data on the frequency of the 13910*T allele were collected from 52 countries across Europe, the Near East, and North Africa. The 13915*G allele was available for 30 countries, but was studied in only 16 Near Eastern and North African countries, as it is absent in Europe. The findings indicate very robust, linear relationships between allele frequencies and the genetic factors examined. The strong correlation between the occurrence of the 13910*T allele and Yamnaya ancestry supports the hypothesis that 13910*T originated from the steppe Yamnaya culture. However, its subsequent dissemination can be attributed to a series of regional male founder events and the spread of specific Y haplogroups, particularly Y haplogroup I1. Conversely, the current occurrence of the 13915*G allele appears to have a less complex origin, associated with the geographically constrained expansion of pastoral populations with Natufian ancestry and Y haplogroup J1 in the Arabian Peninsula.
Reassessing Parity-Related Variation in Female Body Morphology: A Matched Analysis in a Contemporary Population.
Lee J, Park J
Am J Hum Biol · 2026 May · PMID 42144854 · Full text
OBJECTIVES: Morphological differences between parous and nulliparous women have long been interpreted as reproductive signatures. However, such patterns may instead reflect demographic composition. This study aimed to re...
OBJECTIVES: Morphological differences between parous and nulliparous women have long been interpreted as reproductive signatures. However, such patterns may instead reflect demographic composition. This study aimed to reassess parity-related morphological variation by reducing confounding from age and BMI using propensity score matching (PSM). METHODS: Anthropometric data from 1339 Korean women aged 20-39 years were analyzed. Forty-five direct and derived body dimensions, collected following ISO 7250-1:2017, were compared between parous and nulliparous women before and after 1:1 nearest-neighbor PSM on age and BMI. Group differences were examined for torso breadths, depths, circumferences, and proportional indices. RESULTS: Unadjusted analyses reproduced well-known findings: parous women showed greater abdominal breadths and depths, larger circumferences, and adiposity patterns commonly attributed to childbirth. After PSM, however, most differences-including widely cited markers of lower-body enlargement and postpartum contour change-were substantially attenuated or statistically nonsignificant. Only a small number of proportional indices (e.g., underbust/weight, waist/weight, elbow/weight) retained modest differences, indicating that parity leaves limited, anatomically localized morphological signatures rather than broad structural changes. CONCLUSIONS: Demographic composition, rather than reproductive biology alone, accounts for much of the observed variation in cross-sectional datasets. Matching-based approaches clarify the independent contribution of parity, strengthen causal inference in anthropometric research, and underscore the need to consider population structure when interpreting life-history-related variation in adult female morphology.
Empowerment at the Core: Decoding the Determinants of Skilled Birth Attendance in Pakistan.
Malik MI
Am J Hum Biol · 2026 May · PMID 42129583 · Publisher ↗
BACKGROUND: The maintenance of hygienic conditions and the provision of appropriate medical care during childbirth are essential to reduce the complications and infections that pose health risks to both expectant mothers...
BACKGROUND: The maintenance of hygienic conditions and the provision of appropriate medical care during childbirth are essential to reduce the complications and infections that pose health risks to both expectant mothers and their newborn babies. Although skilled birth attendance (SBA) has been very much helpful in reducing the biological risks linked to childbirth, it is pertinent to mention that more than 34% of deliveries in Pakistan continue to take place at home without the proper medical care and supervision. OBJECTIVE: The main objective of this proposed work is to explore the correlation between women's empowerment characterized by resources, agency, and relational autonomy and access to skilled birth attendance within the reproductive and sociocultural context of Pakistan. This study also considers the influence of various socioeconomic and demographic factors on this correlation. DATA AND METHODS: The present study utilizes the logistic regression models to estimate average marginal effects, using nationally representative data from currently married women aged 15-49 as mentioned in the Pakistan Demographic and Health Survey 2017-18. This analysis aims to evaluate the relative contributions of different empowerment dimensions, while simultaneously controlling for household and demographic characteristics. RESULTS: Women empowerment is a very important part of skilled birth attendance. The relationship between educational empowerment, digital access, specifically ownership of mobile phones and internet usage, and the rejection of norms related to domestic violence substantially enhances the probability of skilled birth attendance. This phenomenon exhibits effects that are comparable to those of conventional determinants, including household wealth and parity. Significant disparities persist in geographic and socio-economic contexts, adversely affecting mothers in Baluchistan, particularly those with larger families. CONCLUSION: This study demonstrates that the empowerment of women within the context of Pakistan's reproductive ecology is essential, rather than ancillary, for reducing biological risks associated with childbirth. It provides comparative insights that are pertinent to the fields of human biology and maternal health research.
An Exploratory Analysis of the Association Between State-Level Urban Sociodemographic Factors and Fetal Death in Mexico.
Azcorra H, Méndez-Dominguez N
Am J Hum Biol · 2026 May · PMID 42129580 · Publisher ↗
BACKGROUND: Despite evidence linking urban environments to adverse birth outcomes, fetal death remains insufficiently studied within a biocultural perspective. OBJECTIVES: To describe geographic patterns of fetal mortali...
BACKGROUND: Despite evidence linking urban environments to adverse birth outcomes, fetal death remains insufficiently studied within a biocultural perspective. OBJECTIVES: To describe geographic patterns of fetal mortality in Mexico and evaluate the association between state-level fetal death rates and sociodemographic indicators of urban environments. METHODS: An exploratory and population-based study that analyzes all cases (116, 250 cases) of fetal deaths in Mexico recorded between 2020 and 2024. Total (TFDR: all gestational ages), early (EFDR: ≤ 27 weeks of gestation), and late (LFDR: > 27 weeks of gestation) fetal death rates were expressed as the number of fetal deaths per 1000 total births. Simple and multiple linear regression models were used to analyze the association between state-level rate of fetal deaths and the percentage of urban population, population density, income inequality, and crime rate. RESULTS: The national TFDR was 12.96 cases per 1000 births. The highest rates were concentrated in the center of the country (Mexico City: 24.98 and the State of Mexico: 20), while the lowest rates were recorded in the south (Oaxaca: 6.24 and Guerrero: 6.70). The simple regressions showed that the percentage of urban population, population density, and crime incidence rate were positively associated with TFDR and EFDR; the multiple regression showed that the percentage of urban population was significantly associated with these outcomes. Crime rate was associated with LFDR in simple and multiple analyses. CONCLUSION: Recorded fetal death in Mexico shows marked geographic heterogeneity patterned by urban sociodemographic factors that reflect structural stressors and ecological pressures inherent to modern metropolitan life.
Trends in Systemic Inflammation and Its Relation to Socioeconomic Status in US Adults, 1971-2018.
Murasko J
Am J Hum Biol · 2026 Apr · PMID 42036305 · Publisher ↗
Systemic inflammation occurs when the immune system is chronically active due to repeated harmful exposures or dysregulation of the immune process. It is associated with the prevalence and poorer prognoses of many chroni...
Systemic inflammation occurs when the immune system is chronically active due to repeated harmful exposures or dysregulation of the immune process. It is associated with the prevalence and poorer prognoses of many chronic diseases. Like many health indicators, its burden is often found to be greater in those of lower socioeconomic status. Little is known about how levels of systemic inflammation have changed over time in populations, nor how such changes may relate to socioeconomic status. This study uses data from National Health and Nutrition Examination Surveys (NHANES) to evaluate inflammation trends in the US population between the 1970s and 2010s. The results indicate a shift in structural immunity for the US adult population that corresponds with increasing systemic inflammation over time, with the trend being modestly stronger at lower income levels.
Association Between Vegetarian Diet and Bone Mineral Density Assessed by Quantitative Ultrasound in Young Adult Women.
Falbová D, Sulis S, Švábová P … +2 more , Hozáková A, Vorobeľová L
Am J Hum Biol · 2026 Apr · PMID 42036299 · Publisher ↗
OBJECTIVES: The association between vegetarian dietary patterns and bone health remains inconsistent, particularly in young adult populations. This study aimed to investigate the association between adherence to a vegeta...
OBJECTIVES: The association between vegetarian dietary patterns and bone health remains inconsistent, particularly in young adult populations. This study aimed to investigate the association between adherence to a vegetarian dietary pattern and bone mineral density (BMD) in a sample of young adult women. METHODS: The study included 648 young adult women from Slovakia (67 reporting adherence to a vegetarian diet and 581 omnivores). BMD was assessed using quantitative ultrasonography. Baseline demographic and lifestyle information was collected using a structured questionnaire. Linear regression analyses were applied to examine independent associations between dietary pattern and BMD. RESULTS: Women reporting adherence to a vegetarian diet exhibited significantly higher speed of sound (SOS) at the radius (4111.0 ± 124.7 vs. 4068.4 ± 111.2 m/s; p = 0.017) and higher z-score (0.09 ± 1.29 vs. -0.27 ± 1.09; p = 0.036) compared with omnivorous women. In linear regression analyses, adherence to a vegetarian dietary pattern was independently associated with higher SOS and z-score values, whereas smoking status, physical activity, and body weight were not retained in the final models. CONCLUSIONS: Women reporting adherence to a vegetarian dietary pattern exhibited higher SOS and z-score values at the radius compared with their omnivorous peers. These findings suggest that adherence to a vegetarian dietary pattern is associated with differences in bone characteristics in young adult women.
Gendering the Menstrual Cycle in Behavioral Neuroendocrinology.
Duchesne A, Jhajj KK, White N
Am J Hum Biol · 2026 Apr · PMID 42015464 · Full text
The menstrual cycle is increasingly described as a "vital sign of the female body," with the literature suggesting cycle-related brain and behavioral changes. With growing interest in the effects that the menstrual cycle...
The menstrual cycle is increasingly described as a "vital sign of the female body," with the literature suggesting cycle-related brain and behavioral changes. With growing interest in the effects that the menstrual cycle has on the brain, body and mind, characterizing what constitutes healthy cycle-related change has become a central goal of behavioral neuroendocrinology. Considering the epistemological importance of research in behavioral neuroendocrinology for shaping our understanding of cycle-related effects in menstruating people, a critical examination of how the menstrual cycle is operationalized and studied in this field is warranted. In this narrative review, we first describe some methodological gold standards for investigating the menstrual cycle as an acontextual sex-related neurohormonal phenomenon, while highlighting ongoing limitations. We then introduce alternative conceptualizations that operationalize the menstrual cycle as context-contingent and demonstrate the importance of environmental experiences, particularly stress, in influencing cycle-related brain and behavioral changes. Grounded in a feminist/queer approach to sex/gender difference, we propose a conceptualization of the menstrual cycle that integrates gendered sources of stress and discuss the potential of this approach to enable a more representative operationalization that better accounts for its inherent variability.
Socioeconomic and Environmental Determinants of Child Growth: Evidence From the Pakistan Demographic and Health Survey 2017-2018.
Sang A, Ibupoto MH, Mirjat AJ … +3 more , Qiu X, Yankui S, Shah KA
Am J Hum Biol · 2026 Apr · PMID 42015391 · Publisher ↗
INTRODUCTION: Child growth is a critical indicator of population health and human development. In many low- and middle-income countries, children continue to experience growth faltering due to socioeconomic inequalities...
INTRODUCTION: Child growth is a critical indicator of population health and human development. In many low- and middle-income countries, children continue to experience growth faltering due to socioeconomic inequalities and environmental constraints. This study examines the socioeconomic and environmental determinants of child growth outcomes in Pakistan using nationally representative data from the Pakistan Demographic and Health Survey 2017-2018. METHODS: A quantitative cross-sectional analysis was conducted on children aged 0-59 months with available anthropometric measurements. Child growth was assessed using height-for-age (stunting), weight-for-age (underweight), and weight-for-height (wasting) indicators based on standards of the World Health Organization. Descriptive statistics and multivariate logistic regression models were applied to identify significant determinants of growth outcomes. RESULTS: The results indicate that approximately 37%-40% of children in Pakistan suffer from stunting, while about 23% are underweight and 8% experience wasting. Household wealth, maternal education, sanitation facilities, and access to safe drinking water significantly influence child growth outcomes. Children from poorer households and those whose mothers have no formal education are more likely to experience growth deficiencies. Environmental conditions such as unimproved sanitation and lack of safe water also increase the likelihood of undernutrition. CONCLUSION: The findings highlight the importance of addressing socioeconomic inequalities and environmental health conditions to improve child growth outcomes in Pakistan. Policy interventions aimed at poverty reduction, maternal education, and improved water and sanitation infrastructure may significantly contribute to better child health and development.
Navigating Practical, Political, and Ethical Challenges of Long-Term Human Biology Field Research: The Shuar Health and Life History Project.
Snodgrass JJ, Madimenos FC, Liebert MA … +5 more , Urlacher SS, Cepon-Robins TJ, Gildner TE, Bribiescas RG, Sugiyama LS
Am J Hum Biol · 2026 Apr · PMID 41999134 · Full text
Major advances in understanding human biology and health have been made possible by long-term field research projects with Indigenous peoples, whose ecological settings and lifeways are distinct from majority populations...
Major advances in understanding human biology and health have been made possible by long-term field research projects with Indigenous peoples, whose ecological settings and lifeways are distinct from majority populations in high-income settings. Long-term fieldwork is central to human biology, yet much about this research approach remains opaque. This paper considers a single long-term study-the Shuar Health and Life History Project in Amazonian Ecuador-and discusses how we have navigated practical, political, and ethical challenges of initiating and maintaining a two-decade long collaborative project with integrative field and laboratory components. By enhancing transparency and offering logistical and ethical insights, our goal is to provide guidance to researchers. We offer three sets of conclusions and recommendations. First, our highly integrative approach allows us to ask important scientific questions and answer them in innovative ways. We recommend investment in broad theoretical and methodological training and study design, as well as a project structure that nurtures students' ideas. Second, a project like ours is extremely challenging to operate, requiring major sustained commitment of time and funding to maintain the fieldsite and laboratories. We recommend that scientists initiating major field projects be cognizant of these enormous costs and challenges, develop supportive relationships among collaborating researchers, and incorporate flexibility and excess capacity. Finally, sustainable long-term investment in research communities must be prioritized, and the science and outreach efforts require tailoring to local conditions and realities. We recommend that researchers invest deeply in communities, building trust and establishing long-term relationships that are mutually beneficial.
Apolipoprotein E Polymorphism and Reproductive Patterns Among Postreproductive Women.
Bartecka P, Galbarczyk A, Klimek M … +2 more , Nenko I, Jasienska G
Am J Hum Biol · 2026 Apr · PMID 41999124 · Full text
OBJECTIVES: Traits that are detrimental for health may persist in populations because they are advantageous for reproduction. Apolipoprotein E is a protein involved in lipid metabolism, and it is encoded by a polymorphic...
OBJECTIVES: Traits that are detrimental for health may persist in populations because they are advantageous for reproduction. Apolipoprotein E is a protein involved in lipid metabolism, and it is encoded by a polymorphic gene (ApoE) with three alleles: ApoE2, ApoE3, and ApoE4. ApoE4 allele is associated with elevated cholesterol levels, and increased risk of various metabolic and age-related diseases, such as cardiovascular disease and dementia. Because lipids are crucial for steroid hormone synthesis and thus the ovarian function, ApoE4 allele may be associated with enhanced fertility. Therefore, we hypothesize that women with different ApoE genotypes will exhibit differences in reproductive history traits. METHODS: Participants included 360 postreproductive women aged 45-92 from a Polish rural population living at the Mogielica Human Ecology Study Site. General linear models were used to test differences in age at menarche, age at first reproduction, number of children born, mean interbirth interval and age at last reproduction across different ApoE genotypes. RESULTS: No significant differences were observed between ApoE genotypes in any of the tested reproductive history parameters. CONCLUSION: Although some of the previous research has suggested that carriers of ApoE4 have more successful reproduction, we found no evidence supporting such an association among postreproductive aged women from a traditional, agricultural community. It is possible that ApoE4 may confer reproductive advantages only under specific ecological or lifestyle conditions, such as high pathogen burden or low-energy diet.
Population-Specific Circadian Drivers and MTNR1B Predict Arctic Morning Cortisol.
Gubin D, Kolomeichuk S, Danilenko K … +12 more , Stefani O, Markov A, Petrov I, Voronin K, Mezhakova M, Borisenkov M, Shigabaeva A, Boldyreva J, Petrova J, Alkhimova L, Weinert D, Cornelissen G
Am J Hum Biol · 2026 Apr · PMID 41983375 · Publisher ↗
OBJECTIVE: This study investigated the relationship between morning cortisol concentration and circadian timing of physical activity, light exposure and sleep in Arctic residents, and examined the role of the MTNR1B rs10...
OBJECTIVE: This study investigated the relationship between morning cortisol concentration and circadian timing of physical activity, light exposure and sleep in Arctic residents, and examined the role of the MTNR1B rs10830963 polymorphism on this relationship. METHODS: Circadian parameters were derived from 7-day actigraphy utilizing the ActTrust 2 device with RGB light sensors. Actigraphy and cortisol were assessed in the same 27 (21 women) adult participants longitudinally during winter and summer solstices and spring equinox. Associations with morning cortisol were assessed by correlation and regression analyses, stratified by indigeneity, adjusting for photoperiod, age, and sex. A two-way ANOVA assessed the effects of season and MTNR1B genotype on cortisol. RESULTS: Later timing of physical activity (β = 0.374, p < 0.001), light exposure (β = 0.242, p = 0.028), and bedtime (β = 0.345, p = 0.001) were significantly associated with higher morning cortisol. Stratification revealed that Nonnatives were primarily affected by the timing of light exposure (β = 0.321, p = 0.013), whereas Natives exhibited associations only with the timing of activity and sleep (β = 0.619, p = 0.002), but not light exposure. The MTNR1B rs10830963 genotype modulated cortisol, with G-allele carriers showing lower concentrations. CONCLUSION: Cortisol in Arctic residents is linked to the timing of circadian behavior, with population-specific drivers: Nonnatives integrate both photic and behavioral cues, while the indigenous population relies on behavioral rhythms. MTNR1B polymorphism further modulates cortisol, indicating that environmental timing and genetic background regulate activity of the Hypothalamic-Pituitary-Adrenal axis in extreme photic environments.
Why, Immunologically, Housing-Related Fungi and Endotoxins (and Other Chronic Pro-Inflammatory Stressors) Risk Latent Tuberculosis Reactivation, Severe Asthma, and Translocating and Invasive Infections in Indigenous Communities in Canada.
Burke S
Am J Hum Biol · 2026 Apr · PMID 41972601 · Full text
Type 1/M1/T1 and type 3/M1/T17 pro-inflammatory switches are risks for latent Mycobacterium tuberculosis (Mtb) reactivation and ongoing infection transmission. This paper considers the heavy toll of reactivation risk in...
Type 1/M1/T1 and type 3/M1/T17 pro-inflammatory switches are risks for latent Mycobacterium tuberculosis (Mtb) reactivation and ongoing infection transmission. This paper considers the heavy toll of reactivation risk in Indigenous communities in Canada and the chronic, everyday pro-inflammatory stressors connected with type 3/M1/T17 immune switching, including household fungal and endotoxin exposures that fuel reactivation risk. The paper argues that regular or chronic pro-inflammatory stressors are risks not only for latent Mtb reactivation and ongoing transmission, but also, via compromised type 4/M2/T22 mucosal barrier protections, severe asthma and translocated, possibly invasive, bacterial, viral, and fungal infections. Individual and community efforts to reduce chronic pro-inflammatory stressors are important, but as the immunological, switch-inducing rationale suggests, unless chronic pro-inflammatory risks associated with housing are mediated, tuberculosis reactivation and other health risks will likely persist.
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