About

Mary K. Shenk is a biocultural anthropologist, human behavioral ecologist, and anthropological demographer. Her research interests include marriage, family, kinship, parental investment, fertility, mortality, and inequality. She has conducted field research on the economics of marriage and parental investment in urban South India, the causes of rapid fertility decline in rural Bangladesh, and the effects of market integration on wealth, social networks, and health in rural Bangladesh. Her current work focuses on understanding the foundations of inequality and how these shift with both market integration and adaptation to local environments, as well as exploring the evolutionary demography of human fertility and the psychological mechanisms that underpin human reproduction. Additionally, she studies the behavioral ecology of human kinship, marriage, and family systems.

Research topics

• Sociology
• Political Science
• Demography
• Medicine
• Biology
• Psychology
• Mathematics
• Geography
• Social psychology
• Developmental psychology
• Market economy
• Internal medicine
• Economics
• Gerontology
• Ecology

Selected publications

• Nutrition and Handgrip Strength Among Adults in Rural Matlab, Bangladesh

  American Journal of Human Biology · 2026-03-01

  articleOpen accessSenior author

  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.

  PublisherDOI

• Perspectives and behaviors surrounding planting practices in North America inform genetic conservation realities for American ginseng ( <scp> <i>Panax quinquefolius</i> </scp> )

  Plants People Planet · 2026-03-23

  articleOpen access

  Societal Impact Statement American ginseng is a shade‐obligate, North American medicinal plant that is widely traded and used internationally. To meet global demand, ginseng is cultivated in forest farms in the Appalachian region of the USA and field‐based artificial shade farms in two regions: Ontario, Canada, and Wisconsin, USA. We conducted social research leveraging in‐depth interviews with growers to inform wild population genetics and future crop development efforts by examining how ginseng genetic materials are sourced, selected, and distributed in forest‐based and artificial shade farming systems. We identified patterns in grower practice that inform global conservation efforts in ginseng and other medicinal plants. Summary Understanding the population genetics of threatened medicinal plant species is essential to building effective conservation management strategies that promote sustainable plant use for human health and wellbeing. Yet molecular approaches on their own do not incorporate human perspectives and behaviors, including trading planting stock and intensive cultivation, that may influence genetic population structure. Research continues to assess genetic and phenotypic variation in cultivated and wild ginseng plants; however, the practices associated with ginseng planting have mostly been overlooked. In this study, we incorporated the knowledge of ginseng growers by conducting key informant interviews with artificial shade and forest growers in the U.S.A. and Canada (N = 34) and analyzed these data using Grounded Theory methods. Results from these interviews highlight the importance of artificial shade farms in Wisconsin and Ontario as likely sources of genetic and phenotypic variation in forest‐cultivated and wild‐occurring ginseng populations. Plant selection and seed saving practices were mostly unconscious decisions, and evidence of deliberate selection of genetic materials for specific traits was largely absent. Growers reported that lack of access to local seed sources is an important driver of planting stock movement from artificial shade farms to forest farms that can be used to establish “wild” forest populations. Artificial shade farms were found to produce large seed surpluses, while forest farms reported difficulties obtaining planting stock, leading to heavy reliance on importing non‐local cultivated planting materials. These results highlight the importance of involving growers in future efforts involving planting stock conservation and seed banking for sustainable medicinal plant use.

  PublisherDOI

• Inverse Association Between Betel Quid Use and Diabetes in Rural Bangladesh

  American Journal of Human Biology · 2026-02-01

  articleOpen access

  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: ≥ 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.

  PublisherDOI

• An evolutionary perspective on the use of betel nut and its effects on health outcomes

  Evolution Medicine and Public Health · 2025-12-12

  articleOpen accessSenior author

  Background and objectives: The use of psychoactive substances appears to be a consistent behavior throughout human evolutionary history. In contemporary research, this is often attributed to the addictive properties of such substances; an evolutionary perspective offers a more nuanced view. We take the case of betel nut use in Bangladesh to investigate the relationship between betel quid and chronic health outcomes, and to consider local disease ecology and evolutionary explanations for consumption of this psychoactive substance. Methodology: We analyzed data from a random sample of 765 women and 499 men in Matlab, Bangladesh, to assess associations between betel quid use and anemia, type 2 diabetes (T2D), hypertension, and inflammation (C-reactive protein, CRP). Results: -value = .007). For other outcomes, there were important interactions between betel quid use and gender. A positive association with anemia (aOR: 2.56, CI: 1.62, 4.04) and inverse associations with diabetes and hypertension (aOR: 0.38, CI: 0.22, 0.66; aOR: 0.41, 1.03, respectively) were apparent among men, but not women (anemia: aOR: 1.03, CI: 0.72, 1.49; diabetes: aOR: 0.98, CI: 0.58, 1.65; hypertension: aOR: 1.25, CI: 0.85, 1.85). Conclusions and implications: Betel quid use was inversely associated with inflammation and, among men, positively associated with anemia and inversely associated with diabetes and hypertension. Together, these findings suggest that the use of betel quid, and possibly other addictive substances, may have been a behavioral adaptation to diverse socioecological challenges.

  PublisherDOI

• Maternal religiosity and social support to mothers: helpers’ religious identity matters

  Religion Brain & Behavior · 2025-02-19 · 2 citations

  article

  Data and statistical script: The statistical script associated with this study is made public https://osf.io/6mpbe/. However, since the data we use in this study are part of larger project and will be made public in a future, we cannot currently share the raw dataset. Therefore, we provide access to the processed dataset prepared for analyses. Reader may go through the full script or skip the data curation part directly to load prepared dataset and run the statistical models.

  PublisherDOI

• Author response for "The role of parental religiosity in shaping paternal investment: evidence from Bangladesh and India"

  2025-07-28

  peer-reviewSenior author
  PublisherDOI

• The two-tiered model resolves key questions on extrinsic mortality and fertility

  Behavioral and Brain Sciences · 2025-01-01

  article1st authorCorresponding

  I argue that the two-tier model represents a clear step forward, resolving debates and disentangling complexity in our understanding of human life history strategies. I relate the model to findings from my previous work, as well as to embodied capital and market integration, providing relevant schematics. I then discuss the timing of exposure to mortality cues and the age of the deceased, discussing what the two-tier model does and does not add to these debates.

  PublisherDOI

• Inverse association between betel quid use and diabetes in rural Bangladesh

  medRxiv · 2025-07-15 · 1 citations

  preprintOpen access

  Abstract 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 1c ≥ 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 a file drawer effect may contribute to differences between these findings and other observational studies.

  PublisherOA PDFDOI

• Physical Activity and Irritable Bowel Syndrome: The Role of Evolutionary Mismatch in Chronic Disease Risk

  American Journal of Biological Anthropology · 2025-08-01 · 1 citations

  articleOpen accessSenior author

  OBJECTIVES: Rising rates of noncommunicable diseases have been attributed to evolutionary mismatch between past physical activity and sedentary, post-industrial behavior. Epidemiologic research suggests that sedentism increases irritable bowel syndrome (IBS) risk. We test this association with a population sample to assess whether physical activity mismatch is associated with IBS. MATERIALS AND METHODS: This study recruited Pennsylvanians (age- and sex- matched to state population) to complete an online survey documenting digestion, demographics, and physical activity. IBS was diagnosed using Rome IV criteria, and data were analyzed using binary logistic regression. RESULTS: The sample included 921 individuals (55.3% F; mean age = 38.78) with an IBS prevalence of 28.8%. Exercise vigor (none/low) was significantly associated with increased IBS risk [OR 1.469, 95% CI: 1.168-2.126, p = 0.0154], though other measures of exercise were not. BMI was a strong predictor of IBS continuously (sample mean BMI = 28.61) [OR 1.029, 95% CI: 1.011-1.048, p = 0.002], with higher BMI increasing IBS risk, especially for those overweight (25 < BMI < 30) [OR 1.734, 95% CI: 1.129-2.664, p = 0.012] or obese (BMI > 30) [OR 2.062, 95% CI: 1.361-3.125, p = 0.001]. BMI significantly mediated the relationship between exercise vigor and IBS. DISCUSSION: Most research finds IBS is an illness driven by the environment, with exercise playing a protective role in disease risk. Our findings suggest that mismatch due to exercise levels alone is likely not a major driver of disease; instead, IBS may be driven by longitudinal effects of exercise (proxied here by BMI) alongside other environmental and behavioral factors contributing to energetic balance, such as diet and stress.

  PublisherOA PDFDOI

• Life Course Timing of Mortality Exposure and Fertility Behavior

  Population Research and Policy Review · 2025-04-30 · 4 citations

  articleOpen accessSenior author

  Abstract Mortality and fertility are important, intricately linked drivers of population change. Although past demographic research has focused largely on population-level mortality rates, individual-level mortality experiences can also shape fertility. The timing of mortality exposure over the life course might distinctly shape individual-level fertility behavior, with some time periods being more sensitive than others. Using detailed data from a sample of reproductive-aged women in Matlab, Bangladesh, this study investigates how mortality exposure, specifically to family bereavements, across three time periods (the focal woman’s childhood, adolescence, and post-marriage adulthood) is linked to fertility quantum and tempo. Results suggest exposure to kin mortality is associated with an increased fertility quantum despite delaying fertility tempo. We also find that mortality exposure post marriage (rather than in a woman’s childhood or adolescence) is the most crucial life course period in terms of the relationship between mortality exposure and fertility behavior. These findings distinctively underscore the need to account for mortality exposure in our understanding of individual-level fertility behavior, and also the importance of specific environmental components, such as the life course timing of mortality exposure, to better understand this relationship. These findings are consistent with previous literature on the association of mortality exposure with fertility, but our novel life course analyses contradict expectations that early life mortality exposure will be especially influential on later fertility.

  PublisherOA PDFDOI

Recent grants

• NIH Grant F32HD048064

  NIH · $128k · 2008

• COLLABORATIVE RESEARCH: A multidimensional investigation of the dynamics of market transition and social change

  NSF · $216k · 2018–2025

• Collaborative Research: Evolutionary and Comparative Models of the Demographic Transition

  NSF · $298k · 2010–2014

• COLLABORATIVE RESEARCH: A multidimensional investigation of the dynamics of market transition and social change

  NSF · $157k · 2015–2018

Frequent coauthors

• Rebecca Sear

  UCLouvain

  33 shared

• Siobhán M. Mattison

  University of New Mexico

  32 shared

• Tami Blumenfield

  University of New Mexico

  31 shared

• John H. Shaver

  21 shared

• Monique Borgerhoff Mulder

  University of California, Davis

  17 shared

• Nurul Alam

  International Centre for Diarrhoeal Disease Research

  15 shared

• Chun‐Yi Sum

  15 shared

• Richard Sosis

  15 shared

Labs

• Center for Human Evolution and DiversityPI

Education

• PhD, Anthropology

  University of Washington

  2005

• MA, Anthropology

  University of Washington

  1996

• BA, Anthropology

  University of New Orleans

  1994