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1. Lifestyle mediates seasonal changes in metabolic health among the yakut (sakha) of northeastern siberia

   https://doi.org/10.1002/ajhb.22879  

   Levy, Stephanie B. ; Leonard, William R. ; Tarskaia, Larissa A. ; Klimova, Tatiana M. ; Fedorova, Valentina I. ; Baltakhinova, Marina E. ; Josh Snodgrass, J. ( June 2016 , American Journal of Human Biology)

   Among indigenous circumpolar populations, extreme seasonality influences food availability and energy metabolism. Furthermore, subsistence patterns and wage labor opportunities shift with season. Thus, health measures among circumpolar populations likely exhibit seasonal changes that are influenced by lifestyle factors. This study examines how markers of cardio‐metabolic health vary between summer and winter as a function of an individual's lifestyle and sex among the Yakut of northeastern Siberia.

   Anthropometric dimensions, serum lipids and glucose levels, blood pressure, and lifestyle data were collected for a sample of 115 Yakut participants (71 women, 44 men) in Berdygestiakh, Sakha Republic, Russia in the summer of 2009 and winter of 2011.

   Men and women experienced significant increases in total and HDL cholesterol and triglyceride levels from summer to winter. Women exhibited winter‐time increases in adiposity and glucose levels. Men who reported greater market integration were more likely to have lower winter blood pressure levels. Additionally, time spent fishing was associated with lower winter‐time LDL cholesterol, while foraging time was associated with higher HDL cholesterol.

   While seasonal changes in anthropometric dimensions were modest, Yakut men and women experienced significant increases in total cholesterol and HDL cholesterol from summer to winter. These results also suggest that while Yakut individuals with greater subsistence participation are more buffered from adverse seasonal changes in cholesterol levels, they may be at a greater risk for winter increases in blood pressure. Furthermore, the interactions between lifestyle and seasonal change in metabolic health appear to differ between Yakut women and men. Am. J. Hum. Biol. 28:868–878, 2016. © 2016Wiley Periodicals, Inc.

    

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2. Lifestyle and patterns of physical activity in Hadza foragers

   https://doi.org/10.1002/ajpa.24846  

   Sayre, M. Katherine ; Anyawire, Mariamu ; Paolo, Bunga ; Mabulla, Audax Z. P. ; Pontzer, Herman ; Wood, Brian M. ; Raichlen, David A. ( September 2023 , American Journal of Biological Anthropology)

   Physically active lifestyles are associated with several health benefits. Physical activity (PA) levels are low in post‐industrial populations, but generally high throughout life in subsistence populations. The Hadza are a subsistence‐oriented foraging population in Tanzania known for being physically active, but it is unknown how recent increases in market integration may have altered their PA patterns. In this study, we examine PA patterns for Hadza women and men who engage in different amounts of traditional foraging.

   One hundred and seventy seven Hadza participants (51% female, 19–87 years) wore an Axivity accelerometer (dominant wrist) for ~6 days during dry season months. We evaluated the effects of age, sex, and lifestyle measures on four PA measures that capture different aspects of the PA profile.

   Participants engaged in high levels of both moderate‐intensity PA and inactivity. Although PA levels were negatively associated with age, older participants were still highly active. We found no differences in PA between participants living in more traditional “bush” camps and those living in more settled “village” camps. Mobility was positively associated with step counts for female participants, and schooling was positively associated with inactive time for male participants.

   The similarity in PA patterns between Hadza participants in different camp types suggests that high PA levels characterize subsistence lifestyles generally. The sex‐based difference in the effects of mobility and schooling on PA could be a reflection of the Hadza's gender‐based division of labor, or indicate that changes to subsistence‐oriented lifestyles impact women and men in different ways.

    

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3. A short-term religious “fast” from animal products has a minimal impact on cardiometabolic health biomarkers irrespective of concurrent shifts in distinct plant-based food groups

   https://doi.org/10.1093/ajcn/nqz153  

   Bethancourt, Hilary J. ; Kratz, Mario ; O'Connor, Kathleen ( August 2019 , The American Journal of Clinical Nutrition)

   Plant-based diets may help improve measures of body fat, blood cholesterol, glucose metabolism, and inflammation. However, limited evidence suggests that the health effects of reducing animal products may depend on the quality of plant-based foods consumed as caloric replacements.

   This study examined how temporarily restricting consumption of meat, dairy, and egg (MDE) products for religious purposes influences cardiometabolic health biomarkers and whether any effects of MDE restriction on biomarkers are modified by concurrent shifts in calories, fish, and distinct plant-based foods.

   This study followed a sample of 99 individuals in the United States with varying degrees of adherence to Orthodox Christian (OC) guidance to abstain from MDE products during Lent, the 48-d period prior to Easter. Dietary composition was estimated from FFQs and 7-d food records; measures of body fat, blood lipids, glucose metabolism, and inflammation were collected prior to and at the end of Lent.

   Each serving decrease in MDE products was associated with an average −3.7% (95% CI: −5.5%, −2.0%; P < 0.0001) and −3.6% (95% CI: −5.8%, −1.3%; P = 0.003) change in fasting total and LDL blood cholesterol, respectively, which were partly explained by minor weight loss. However, the total/HDL cholesterol ratio did not significantly decrease due to an average −3.2% (95% CI: −5.8%, −0.6%; P = 0.02) change in HDL cholesterol. No associations between MDE restrictions and shifts in measures of body fat, glucose, insulin, or C-reactive protein were observed. The data could not provide evidence that changes in cardiometabolic health biomarkers in relation to MDE restriction were modified by concurrent shifts in calories, fish, or plant-based foods.

   Temporary MDE restrictions practiced by this sample of OCs in the United States during Lent had minimal effects on cardiometabolic disease risk factors. Further research among larger samples of OCs is needed to understand how nutritionally distinct and complex combinations of plant-based foods may modify the health effects of religious fasting from MDE products.

    

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4. Pathogen disgust sensitivity protects against infection in a high pathogen environment

   https://doi.org/10.1073/pnas.2018552118  

   Cepon-Robins, Tara J. ; Blackwell, Aaron D. ; Gildner, Theresa E. ; Liebert, Melissa A. ; Urlacher, Samuel S. ; Madimenos, Felicia C. ; Eick, Geeta N. ; Snodgrass, J. Josh ; Sugiyama, Lawrence S. ( February 2021 , Proceedings of the National Academy of Sciences)

   Disgust is hypothesized to be an evolved emotion that functions to regulate the avoidance of pathogen-related stimuli and behaviors. Individuals with higher pathogen disgust sensitivity (PDS) are predicted to be exposed to and thus infected by fewer pathogens, though no studies have tested this directly. Furthermore, PDS is hypothesized to be locally calibrated to the types of pathogens normally encountered and the fitness-related costs and benefits of infection and avoidance. Market integration (the degree of production for and consumption from market-based economies) influences the relative costs/benefits of pathogen exposure and avoidance through sanitation, hygiene, and lifestyle changes, and is thus predicted to affect PDS. Here, we examine the function of PDS in disease avoidance, its environmental calibration, and its socioecological variation by examining associations among PDS, market-related lifestyle factors, and measures of bacterial, viral, and macroparasitic infection at the individual, household, and community levels. Data were collected among 75 participants (ages 5 to 59 y) from 28 households in three Ecuadorian Shuar communities characterized by subsistence-based lifestyles and high pathogen burden, but experiencing rapid market integration. As predicted, we found strong negative associations between PDS and biomarkers of immune response to viral/bacterial infection, and weaker associations between PDS and measures of macroparasite infection, apparently mediated by market integration-related differences. We provide support for the previously untested hypothesis that PDS is negatively associated with infection, and document variation in PDS indicative of calibration to local socioeconomic conditions. More broadly, findings highlight the importance of evolved psychological mechanisms in human health outcomes.

    

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5. Brown adipose tissue, energy expenditure, and biomarkers of cardio‐metabolic health among the Yakut (Sakha) of northeastern Siberia

   https://doi.org/10.1002/ajhb.23175  

   Levy, Stephanie B. ; Klimova, Tatiana M. ; Zakharova, Raisa N. ; Federov, Afanasiy I. ; Fedorova, Valentina I. ; Baltakhinova, Marina E. ; Leonard, William R. ( October 2018 , American Journal of Human Biology)

   This study provides the first investigation of non‐shivering thermogenesis (NST) and brown adipose tissue (BAT) activity among an indigenous circumpolar population, the Yakut of northeastern Siberia. The study also examines the health significance of BAT activity in this population by testing the relationships between BAT thermogenesis and biomarkers of cardio‐metabolic disease risk, such as percent body fat and blood glucose and cholesterol levels.

   Data were collected in the Sakha Republic (Yakutia) for 31 men and 43 women. Change in energy expenditure and BAT thermogenesis were quantified after a 30‐minute mild cooling condition. Anthropometric dimensions, blood glucose, and lipid levels were also collected.

   On average, the skin temperature of the supraclavicular area was constant after cooling while the skin temperature of a point on the sternum dropped significantly (P < .001), thus suggesting the presence of active supraclavicular BAT among Yakut adults. Participants with evidence of greater BAT thermogenesis exhibited a larger percent change in energy expenditure (% ΔEE) and an increase in respiratory quotient (RQ) after cooling (P ≤ .05). While there was no relationship between BAT activity and blood lipid levels, BAT thermogenesis was positively associated with blood glucose levels (P < .01).

   Yakut adults exhibit evidence of active BAT deposits. Given that there is a significant relationship between BAT activity and % ΔEE, it is possible that BAT plays a role in NST among Yakut adults. While the relationship between BAT and body composition is inconclusive, participants with greater BAT seemed to preferentially utilize glucose during cold stress exposure.

    

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