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Research with humans and non-human primate species has found an association between social rank and individual health. Among humans, a robust literature in industrial societies has shown that each step down the rank hierarchy is associated with increased morbidity and mortality. Here, we present supportive evidence for the social gradient in health drawing on data from 289 men (18+ years of age) from a society of foragers-farmers in the Bolivian Amazon (Tsimane'). We use a measure of social rank that captures the locally perceived position of a man in the hierarchy of important people in a village. In multivariate regression analysis we found a positive and statistically significant association between social rank and three standard indicators of nutritional status: body mass index (BMI), mid-arm circumference, and the sum of four skinfolds. Results persisted after controlling for material and psychosocial pathways that have been shown to mediate the association between individual socioeconomic status and health in industrial societies. Future research should explore locally-relevant psychosocial factors that may mediate the association between social status and health in non-industrial societies. [ABSTRACT FROM AUTHOR]

Water is essential for survival, but one in three individuals worldwide (2.2 billion people) lacks access to safe drinking water. Water intake requirements largely reflect water turnover (WT), the water used by the body each day. We investigated the determinants of human WT in 5604 people from the ages of 8 days to 96 years from 23 countries using isotope-tracking ( 2 H) methods. Age, body size, and composition were significantly associated with WT, as were physical activity, athletic status, pregnancy, socioeconomic status, and environmental characteristics (latitude, altitude, air temperature, and humidity). People who lived in countries with a low human development index (HDI) had higher WT than people in high-HDI countries. On the basis of this extensive dataset, we provide equations to predict human WT in relation to anthropometric, economic, and environmental factors.

In mammals, trait variation is often reported to be greater among males than females. However, to date, mainly only morphological traits have been studied. Energy expenditure represents the metabolic costs of multiple physical, physiological, and behavioral traits. Energy expenditure could exhibit particularly high greater male variation through a cumulative effect if those traits mostly exhibit greater male variation, or a lack of greater male variation if many of them do not. Sex differences in energy expenditure variation have been little explored. We analyzed a large database on energy expenditure in adult humans (1494 males and 3108 females) to investigate whether humans have evolved sex differences in the degree of interindividual variation in energy expenditure. We found that, even when statistically comparing males and females of the same age, height, and body composition, there is much more variation in total, activity, and basal energy expenditure among males. However, with aging, variation in total energy expenditure decreases, and because this happens more rapidly in males, the magnitude of greater male variation, though still large, is attenuated in older age groups. Considerably greater male variation in both total and activity energy expenditure could be explained by greater male variation in levels of daily activity. The considerably greater male variation in basal energy expenditure is remarkable and may be explained, at least in part, by greater male variation in the size of energy-demanding organs. If energy expenditure is a trait that is of indirect interest to females when choosing a sexual partner, this would suggest that energy expenditure is under sexual selection. However, we present a novel energetics model demonstrating that it is also possible that females have been under stabilizing selection pressure for an intermediate basal energy expenditure to maximize energy available for reproduction., Competing Interests: Conflicts of interest The authors have no conflicts of interest to declare., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Lower ambient temperature (T a ) requires greater energy expenditure to sustain body temperature. However, effects of T a on human energetics may be buffered by environmental modification and behavioral compensation. We used the IAEA DLW database for adults in the USA (n = 3213) to determine the effect of T a (-10 to +30°C) on TEE, basal (BEE) and activity energy expenditure (AEE) and physical activity level (PAL). There were no significant relationships (p > 0.05) between maximum, minimum and average T a and TEE, BEE, AEE and PAL. After adjustment for fat-free mass, fat mass and age, statistically significant (p < 0.01) relationships between TEE, BEE and T a emerged in females but the effect sizes were not biologically meaningful. Temperatures inside buildings are regulated at 18-25°C independent of latitude. Hence, adults in the US modify their environments to keep TEE constant across a wide range of external ambient temperatures., Competing Interests: The authors declare no conflicts of interest., (© 2022 The Authors.)

Objectives: Recent research suggests that brown adipose tissue (BAT) plays a functional role in non-shivering thermogenesis; however, few studies have examined population variation in BAT or its relationship with other mechanisms of adaptation to cold stress. This study characterized BAT thermogenesis and other adaptive responses to low temperatures among Indigenous Siberian young adults and young adults living near Chicago, IL., Materials and Methods: We recruited 72 Yakut participants (42 females; 30 males) and 54 participants in Evanston, IL (40 females; 14 males). Anthropometric dimensions and resting metabolic rate (RMR) were measured, and we calculated percent divergence in RMR from expected values (divRMR). We also quantified change in supraclavicular temperature, sternum temperature, and energy expenditure after a mild cooling condition., Results: Participants in Yakutia were less likely to shiver during the cooling condition (p < .05) and exhibited significantly greater evidence of BAT thermogenesis, warmer sternum temperatures, and higher divRMR than participants in Evanston (p < .05). Additionally, the relationship between change in supraclavicular temperature and energy expenditure differed between the two samples., Conclusions: Yakut young adults displayed greater evidence of BAT thermogenesis in response to mild cooling compared with young adults living near Chicago, IL. Furthermore, the relationship between BAT thermogenesis and change in energy expenditure appears to be stronger among Yakut adults. Adults that exhibited greater metabolic response to cold stress, such as higher BAT thermogenesis and divRMR, maintained warmer sternum temperatures. These results highlight the degree to which adaptation to cold climates involves multiple integrated biological pathways., (© 2022 Wiley Periodicals LLC.)

While human adaptability is regarded as a classical topic in anthropology, recent work provides new insight into metabolic adaptations to cold climates and the role of phenotypic plasticity in human evolution. A growing body of literature demonstrates that adults retain brown adipose tissue (BAT) which may play a role in non-shivering thermogenesis. In this narrative review, we apply the timescales of adaptation framework in order to explore the adaptive significance of human BAT. Human variation in BAT is shaped by multiple adaptive modes (i.e., allostasis, acclimatization, developmental adaptation, epigenetic inheritance, and genetic adaptation), and together the adaptive modes act as an integrated system. We hypothesize that plasticity in BAT facilitated the successful expansion of human populations into circumpolar regions, allowing for selection of genetic adaptations to cold climates to take place. Future research rooted in human energetics and biocultural perspectives is essential for understanding BAT's adaptive and health significance., (© 2021 Wiley Periodicals LLC.)

Low total energy expenditure (TEE, MJ/d) has been a hypothesized risk factor for weight gain, but repeatability of TEE, a critical variable in longitudinal studies of energy balance, is understudied. We examine repeated doubly labeled water (DLW) measurements of TEE in 348 adults and 47 children from the IAEA DLW Database (mean ± SD time interval: 1.9 ± 2.9 y) to assess repeatability of TEE, and to examine if TEE adjusted for age, sex, fat-free mass, and fat mass is associated with changes in weight or body composition. Here, we report that repeatability of TEE is high for adults, but not children. Bivariate Bayesian mixed models show no among or within-individual correlation between body composition (fat mass or percentage) and unadjusted TEE in adults. For adults aged 20-60 y (N = 267; time interval: 7.4 ± 12.2 weeks), increases in adjusted TEE are associated with weight gain but not with changes in body composition; results are similar for subjects with intervals >4 weeks (N = 53; 29.1 ± 12.8 weeks). This suggests low TEE is not a risk factor for, and high TEE is not protective against, weight or body fat gain over the time intervals tested., (© 2022. The Author(s).)

Background: Physical activity may be a way to increase and maintain fat-free mass (FFM) in later life, similar to the prevention of fractures by increasing peak bone mass., Objectives: A study is presented of the association between FFM and physical activity in relation to age., Methods: In a cross-sectional study, FFM was analyzed in relation to physical activity in a large participant group as compiled in the International Atomic Energy Agency Doubly Labeled Water database. The database included 2000 participants, age 3-96 y, with measurements of total energy expenditure (TEE) and resting energy expenditure (REE) to allow calculation of physical activity level (PAL = TEE/REE), and calculation of FFM from isotope dilution., Results: PAL was a main determinant of body composition at all ages. Models with age, fat mass (FM), and PAL explained 76% and 85% of the variation in FFM in females and males < 18 y old, and 32% and 47% of the variation in FFM in females and males ≥ 18 y old, respectively. In participants < 18 y old, mean FM-adjusted FFM was 1.7 kg (95% CI: 0.1, 3.2 kg) and 3.4 kg (95% CI: 1.0, 5.6 kg) higher in a very active participant with PAL = 2.0 than in a sedentary participant with PAL = 1.5, for females and males, respectively. At age 18 y, height and FM-adjusted FFM was 3.6 kg (95% CI: 2.8, 4.4 kg) and 4.4 kg (95% CI: 3.2, 5.7 kg) higher, and at age 80 y 0.7 kg (95% CI: -0.2, 1.7 kg) and 1.0 kg (95% CI: -0.1, 2.1 kg) higher, in a participant with PAL = 2.0 than in a participant with PAL = 1.5, for females and males, respectively., Conclusions: If these associations are causal, they suggest physical activity is a major determinant of body composition as reflected in peak FFM, and that a physically active lifestyle can only partly protect against loss of FFM in aging adults., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition.)

Understanding the impacts of activity on energy balance is crucial. Increasing levels of activity may bring diminishing returns in energy expenditure because of compensatory responses in non-activity energy expenditures. 1-3 This suggestion has profound implications for both the evolution of metabolism and human health. It implies that a long-term increase in activity does not directly translate into an increase in total energy expenditure (TEE) because other components of TEE may decrease in response-energy compensation. We used the largest dataset compiled on adult TEE and basal energy expenditure (BEE) (n = 1,754) of people living normal lives to find that energy compensation by a typical human averages 28% due to reduced BEE; this suggests that only 72% of the extra calories we burn from additional activity translates into extra calories burned that day. Moreover, the degree of energy compensation varied considerably between people of different body compositions. This association between compensation and adiposity could be due to among-individual differences in compensation: people who compensate more may be more likely to accumulate body fat. Alternatively, the process might occur within individuals: as we get fatter, our body might compensate more strongly for the calories burned during activity, making losing fat progressively more difficult. Determining the causality of the relationship between energy compensation and adiposity will be key to improving public health strategies regarding obesity., Competing Interests: Declaration of interests The authors have no conflicts of interest to declare., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Total daily energy expenditure ("total expenditure") reflects daily energy needs and is a critical variable in human health and physiology, but its trajectory over the life course is poorly studied. We analyzed a large, diverse database of total expenditure measured by the doubly labeled water method for males and females aged 8 days to 95 years. Total expenditure increased with fat-free mass in a power-law manner, with four distinct life stages. Fat-free mass-adjusted expenditure accelerates rapidly in neonates to ~50% above adult values at ~1 year; declines slowly to adult levels by ~20 years; remains stable in adulthood (20 to 60 years), even during pregnancy; then declines in older adults. These changes shed light on human development and aging and should help shape nutrition and health strategies across the life span., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Objectives: Evolutionary theorists have debated the adaptive significance of developmental plasticity in organisms with long lifespans such as humans. This debate in part stems from uncertainty regarding the timing of sensitive periods. Does sensitivity to environmental signals fluctuate across development or does it steadily decline? We investigated developmental plasticity in brown adipose tissue (BAT) among indigenous Siberians in order to explore the timing of phenotypic sensitivity to cold stress., Methods: BAT thermogenesis was quantified using infrared thermal imaging in 78 adults (25 men; 33 women). Cold exposure during gestation, infancy, early childhood, middle childhood, and adolescence was quantified using: (1) the average ambient temperature across each period; (2) the number of times daily temperature dropped below -40°F during each period. We also assessed past cold exposure with a retrospective survey of participation in outdoor activities., Results: Adult BAT thermogenesis was significantly associated with the average temperature (p = 0.021), the number of times it was below -40°F (p = 0.026), and participation in winter outdoor activities (p = 0.037) during early childhood., Conclusions: Our results suggest that early childhood represents an important stage for developmental plasticity, and that culture may play a critical role in shaping the timing of environmental signals. The findings highlight a new pathway through which the local consequences of global climate change may influence human biology, and they suggest that ambient temperature may represent an understudied component of the developmental origins of health and disease., (© 2021 Wiley Periodicals LLC.)

The doubly labeled water (DLW) method measures total energy expenditure (TEE) in free-living subjects. Several equations are used to convert isotopic data into TEE. Using the International Atomic Energy Agency (IAEA) DLW database (5,756 measurements of adults and children), we show considerable variability is introduced by different equations. The estimated rCO 2 is sensitive to the dilution space ratio (DSR) of the two isotopes. Based on performance in validation studies, we propose a new equation based on a new estimate of the mean DSR. The DSR is lower at low body masses (<10 kg). Using data for 1,021 babies and infants, we show that the DSR varies non-linearly with body mass between 0 and 10 kg. Using this relationship to predict DSR from weight provides an equation for rCO 2 over this size range that agrees well with indirect calorimetry (average difference 0.64%; SD = 12.2%). We propose adoption of these equations in future studies., Competing Interests: The authors declare no competing interests., (© 2021 The Authors.)

Some research suggests women are more likely to allocate additional resources to their children than are men. This perception has influenced policies such as in-kind food transfer programs and cash transfer programs, which often target women recipients. We assess whether targeting in-kind rice transfers to female versus male adult household members has a differential impact on children's short-run nutritional status. We estimate the impacts of transfers of edible rice and rice seeds, randomly allocated to female or male adults, on three anthropometric indicators: BMI-for-age, arm-muscle area, and triceps skinfold thickness. The trial includes 481 children aged 3-11 years in a horticultural-foraging society of native Amazonians in Bolivia. On average, the gender of the transfer recipient does not influence child anthropometric dimensions, possibly due to norms of cooperation and sharing within and between households. We find limited evidence of heterogeneity in impacts. Transfers to women help children who were growth stunted at baseline to partially catch-up to their better-nourished age-sex peers and help boys (but not girls) and children in higher-income households increase their BMI-for-age. The results of this research point to the importance of considering cultural context in determining if allocating food transfers according to gender are most effective., Competing Interests: Declaration of interest statement The authors declare they have no conflicts of interest.

Although the health benefits of exercise and exposure to nature are well established, most evidence of their interaction comes from acute observations of single sessions of activity. However, documenting improved health outcomes requires ongoing interventions, measurement of multiple outcomes, and longitudinal analyses. We conducted a pilot study to guide the development of a protocol for future longitudinal studies that would assess multiple physiological and psychological outcomes. Herein, we report psychological outcomes measured from thirty-eight participants before and after three conditions: a 50 min walk on a forest path, a 50 min walk along a busy road, and a period of activities of daily living. Changes in positive and negative affect, anxiety, perceived stress, and working memory are reported. We benchmark these results to existing studies that used similar protocols and also identify elements of the protocol that might impair recruitment or retention of subjects in longer-term studies. Linear mixed-models regression revealed that walking improved psychological state when compared to activities of daily living, regardless of walk environment ( p < 0.05). Comparison of mean differences showed that forest walks yielded the largest and most consistent improvements in psychological state. Thus, despite a protocol that required a 3.5 h time commitment per laboratory visit, the beneficial effects of walking and exposure to a forested environment were observed.

Objective: This study examined changes in body fat and diet among Tsimane' forager-horticulturalists and assessed how dietary shifts relate to increases in adiposity between 2002 and 2010., Methods: Longitudinal anthropometric and household-level dietary recall data from 365 men and 339 women aged ≥20 years in the Tsimane' Amazonian Panel Study were used. Multilevel mixed-effects models estimated how BMI, body fat percentage, waist circumference, skinfolds, and fat-free mass relate to household consumption of crops, hunted or fished foods, domesticated animal products, cooking oil, and refined grains and sugar., Results: Women's prevalence of overweight and obesity increased from 22.6% and 2.4% in 2002 to 28.8% and 8.9% in 2010, respectively, and BMI increased by 0.60% ± 0.12% per year (P < 0.001). Increases in fat-free mass accounted for some of this observed weight gain among women. Men's prevalence of overweight and obesity increased from 16.2% and 0.7% to 25.0% and 2.2%, respectively, and BMI increased by 0.22% ± 0.09% per year (P = 0.009). Household use of cooking oil increased and was positively associated with female BMI. Consumption of domesticated animal products did not change significantly but was positively associated with female BMI and male waist circumference., Conclusions: Even small increases in energy-dense market-based foods can contribute to adiposity gains among a moderately active, subsistence-based population., (© 2019 The Obesity Society.)

Objectives: 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., Methods: 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., Results: 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)., Conclusions: 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., (© 2018 Wiley Periodicals, Inc.)

Objectives: Previous research has shown that tropical island populations have reduced basal metabolic rates (BMR) associated with the joint influences of heat stress and undernutrition. This study examines variation in BMR among an indigenous population of Indonesia, and compares these data with those collected from earlier studies in Indonesia., Methods: Anthropometric dimensions and BMR were measured on a sample of 35 Indonesian adults (28 men, 7 women) from the rural village of Ngilo-Ilo, East Java., Results: Mean measured BMRs (±SD) were 1433 ± 344 kcal/d in men and 1256 ±257 kcal/d in women, and were not significantly different from estimates using the FAO/WHO/UNU predictive questions. Underweight individuals (BMIs <18.5 kg/m 2 ) had BMRs that were 7.6% below predicted levels, while those with BMIs ≥18.5 kg/m 2 had BMRs that were 8.0% above predicted levels (P < .01). Underweight individuals also had significantly higher respiratory quotients (RQ = .94 vs. .89; P < .05), suggesting lower levels of fat oxidation. Compared to data from previous studies (1929-1979), men of the Ngilo-Ilo sample had similar BMIs (19.8 vs. 19.2 kg/m 2 ), but higher BMRs, after adjusting for age and body weight (+2.1% vs. -5.6%; P < .05)., Conclusions: Among the agriculturalists of Ngilo-Ilo, measured BMRs were low, but not significantly different from those predicted by the FAO/WHO/UNU equations. Among subjects of this sample and from earlier studies, poorer physical nutritional status was associated with reduced BMRs. These results suggest that chronic energy stress has consistently shaped metabolic function among Indonesian rural populations., (© 2018 Wiley Periodicals, Inc.)

Objectives: We assessed associations between child stunting, recovery, and faltering with schooling and human capital skills in a native Amazonian society of horticulturalists-foragers (Tsimane')., Methods: We used cross-sectional data (2008) from 1262 children aged 6 to 16 years in 53 villages to assess contemporaneous associations between three height categories: stunted (height-for-age Z score, HAZ<-2), moderately stunted (-2 ≤ HAZ≤-1), and nonstunted (HAZ>-1), and three categories of human capital: completed grades of schooling, test-based academic skills (math, reading, writing), and local plant knowledge. We used annual longitudinal data (2002-2010) from all children (n = 853) in 13 villages to estimate the association between changes in height categories between the first and last years of measure and schooling and academic skills., Results: Stunting was associated with 0.4 fewer completed grades of schooling (∼24% less) and with 13-15% lower probability of showing any writing or math skills. Moderate stunting was associated with ∼20% lower scores in local plant knowledge and 9% lower probability of showing writing skills, but was not associated with schooling or math and writing skills. Compared with nonstunted children, children who became stunted had 18-21% and 15-21% lower probabilities of showing math and writing skills, and stunted children had 0.4 fewer completed grades of schooling. Stunted children who recovered showed human capital outcomes that were indistinguishable from nonstunted children., Conclusions: The results confirm adverse associations between child stunting and human capital skills. Predictors of growth recovery and faltering can affect human capital outcomes, even in a remote, economically self-sufficient society., (© 2017 Wiley Periodicals, Inc.)

Recent work in rodents has demonstrated that basal activity of the local sympathetic nervous system is critical for maintaining brown adipocyte phenotypes in classic brown adipose tissue (BAT) and white adipose tissue (WAT). Accordingly, we sought to assess the relationship between sympathetic innervation and cold-induced activation of BAT and WAT in lean young adults. Methods: Twenty adult lean normal subjects (10 women and 10 men; mean age ± SD, 23.3 ± 3.8 y; body mass index, 23.7 ± 2.5 kg/m 2 ) underwent 11 C-meta-hydroxyephedrin ( 11 C-HED) and 15 O-water PET imaging at rest and after exposure to mild cold (16°C) temperature. In addition, 18 F-FDG images were obtained during the cold stress condition to assess cold-activated BAT mass. Subjects were divided into 2 groups (high BAT and low BAT) based on the presence of 18 F-FDG tracer uptake. Blood flow and 11 C-HED retention index (RI, an indirect measure of sympathetic innervation) were calculated from dynamic PET scans at the location of BAT and WAT. Whole-body daily energy expenditure (DEE) during rest and cold stress was measured by indirect calorimetry. Tissue level oxygen consumption (MRO 2 ) was determined and used to calculate the contribution of cold-activated BAT and WAT to daily DEE. Results: 18 F-FDG uptake identified subjects with high and low levels of cold-activated BAT mass (high BAT, 96 ± 37 g; low-BAT, 16 ± 4 g). 11 C-HED RI under thermoneutral conditions significantly predicted 18 F-FDG uptake during cold stress ( R 2 = 0.68, P < 0.01). In contrast to the significant increase of 11 C-HED RI during cold in BAT (2.42 ± 0.85 vs. 3.43 ± 0.93, P = 0.02), cold exposure decreased the 11 C-HED RI in WAT (0.44 ± 0.22 vs. 0.41 ± 0.18) as a consequence of decreased perfusion (1.22 ± 0.20 vs. 1.12 ± 0.16 mL/100 g/min). The contribution of WAT to whole-body DEE was approximately 150 kcal/d at rest (149 ± 52 kcal/d), which decreased to approximately 100 kcal/d during cold (102 ± 47 kcal/d). Conclusion: The level of sympathetic innervation, as determined by 11 C-HED RI, can predict levels of functional BAT. Overall, blood flow is the best independent predictor of 11 C-HED RI and 18 F-FDG uptake across thermoneutral and cold conditions. In contrast to BAT, cold stress reduces blood flow and 18 F-FDG uptake in subcutaneous WAT, indicating that the physiologic response is to reduce heat loss rather than to generate heat., (© 2017 by the Society of Nuclear Medicine and Molecular Imaging.)

Objectives: 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., Methods: 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., Results: 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., Conclusions: 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., (© 2016 Wiley Periodicals, Inc.)

Objectives: Adipose tissue hypoxia appears to play a role in promoting chronic inflammation and the development of obesity-related cardiovascular and metabolic diseases, yet the underlying mechanisms are not well understood. The aim of the present research is to examine whether adiponectin levels (an adipocyte-derived hormone with anti-inflammatory properties) are inversely correlated with hemoglobin levels in an indigenous Siberian population., Methods: The study was conducted among 252 Yakut adults (≥18 years; 135 females) from Berdygestiakh, Sakha Republic, Russia. Measurements included anthropometric dimensions (body mass index [BMI], waist circumference [WC], and percent body fat) and blood levels of hemoglobin and adiponectin., Results: Yakut females had higher adiponectin concentrations than males (15.1 ± 9.8 vs. 11.7 ± 10.6 µg/ml; P < 0.001), whereas males had higher hemoglobin levels (14.4 ± 1.4 vs. 12.6 ± 1.5 g/dL; P < 0.001). Body composition measures in both sexes were negatively associated with adiponectin and positively associated with hemoglobin. After adjusting for central adiposity and smoking, adiponectin levels were negatively correlated with hemoglobin levels in men (P < 0.05), but not in women (P = 0.511)., Conclusions: This investigation provides some support for the involvement of hypoxia-related dysregulation of adiponectin associated with obesity and potentially cardiovascular disease. Am. J. Hum. Biol. 28:580-583, 2016. © 2015 Wiley Periodicals, Inc., (© 2015 Wiley Periodicals, Inc.)

Background: Childhood growth stunting is negatively associated with cognitive and health outcomes, and is claimed to be irreversible after age 2., Aim: To estimate growth rates for children aged 2-7 who were stunted (sex-age standardised z-score [HAZ] <-2), marginally-stunted (-2 ≤ HAZ ≤-1) or not-stunted (HAZ >-1) at baseline and tracked annually until age 11; frequency of movement among height categories; and variation in height predicted by early childhood height., Subjects and Methods: This study used a 9-year annual panel (2002-2010) from a native Amazonian society of horticulturalists-foragers (Tsimane'; n = 174 girls; 179 boys at baseline). Descriptive statistics and random-effect regressions were used., Results: This study found some evidence of catch-up growth in HAZ, but persistent height deficits. Children stunted at baseline improved 1 HAZ unit by age 11 and had higher annual growth rates than non-stunted children. Marginally-stunted boys had a 0.1 HAZ units higher annual growth rate than non-stunted boys. Despite some catch up, ∼ 80% of marginally-stunted children at baseline remained marginally-stunted by age 11. The height deficit increased from age 2 to 11. Modest year-to-year movement was found between height categories., Conclusions: The prevalence of growth faltering among the Tsimane' has declined, but hurdles still substantially lock children into height categories.

Research suggests that poorer people have worse health than the better-off and, more controversially, that income inequality harms health. But causal interpretations suffer from endogeneity. We addressed the gap by using a randomized control trial among a society of forager-farmers in the Bolivian Amazon. Treatments included one-time unconditional income transfers (T1) to all households and (T2) only to the poorest 20% of households, with other villages as controls. We assessed the effects of income inequality, absolute income, and spillovers within villages on self-reported health, objective indicators of health and nutrition, and adults' substance consumption. Most effects came from relative income. Targeted transfers increased the perceived stress of participants in better-off households. Evidence suggests increased work efforts among better-off households when the lot of the poor improved, possibly due to a preference for rank preservation. The study points to new paths by which inequality might affect health., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

This brief communication contains a description of the 2002-2010 annual panel collected by the Tsimane' Amazonian Panel Study team. The study took place among the Tsimane', a native Amazonian society of forager-horticulturalists. The team tracked a wide range of socio-economic and anthropometric variables from all residents (633 adults ≥16 years; 820 children) in 13 villages along the Maniqui River, Department of Beni. The panel is ideally suited to examine how market exposure and modernization affect the well-being of a highly autarkic population and to examine human growth in a non-Western rural setting., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Objectives: Socio-demographic indicators closely relate to sleep in industrialized populations. However we know very little about how such factors impact sleep in populations undergoing industrialization. Within populations transitioning to the global economy, the preliminary evidence has found an inconsistent relationship between socio-demographics and sleep complaints across countries and social strata., Materials and Methods: Surveys were conducted on a sample of rural Sakha (Yakut) adults (n = 168) during the autumn of 2103 to assess variation in socio-demographics and sleep complaints, including trouble sleeping and daytime sleepiness. Socio-demographic variables included age, gender, socioeconomic measures, and markers of traditional/market-based lifestyle. We tested whether the socio-demographic variables predicted sleep complaints using bivariate analyses and multiple logistic regressions., Results: Trouble sleeping was reported by 18.5% of the participants and excessive daytime sleepiness (EDS) by 17.3%. Trouble sleeping was significantly predicted by older age, female gender, and mixing traditional and market-based lifestyles. EDS was not significantly predicted by any socio-demographic variable., Discussion: These findings support the few large-scale studies that found inconsistent relationships between measures of socioeconomic status and sleep complaints in transitioning populations. Employing a mix of traditional and market-based lifestyles may leave Sakha in a space of vulnerability, leading to trouble sleeping., (© 2015 Wiley Periodicals, Inc.)

Objectives: To investigate whether having multiple risk factors for cardio-metabolic disease is associated with objectively measured physical activity or sedentary behavior within a sample of Yakut (Sakha) of Siberia., Methods: This cross sectional study involved 63 Yakut adults (32 men) who were measured for cardio-metabolic risk factors. Free living physical activity and sedentary behavior were calculated from waist accelerometry. Correlations and t-tests were used to assess the relationship between moderate-vigorous physical activity (MVPA), sedentary behavior (SB), and individual risk factors and clustering of risk factors., Results: These Yakut were physically active, with 54.4% spending at least 30 min in MVPA, with men being more active than women and women having less favorable cardio-metabolic profiles. These Yakut spent about 7.5 h in SB a day. SB was not related to cardio-metabolic risk factors. MVPA was significantly and negatively related to waist circumference and risk factor clustering in men and the total sample. MVPA was not related to women's risk factors., Conclusions: Objectively measured physical activity was related to lower risk of cardio-metabolic risk factor clustering within this sample of Yakut men, but not women. SB was not related to cardio-metabolic indicators. Physical activity may contribute to a reduction in clustering of metabolic risk factors within indigenous circumpolar populations., (© 2014 Wiley Periodicals, Inc.)

Energetic approaches have been increasingly used to address key issues in Neandertal palaeoecology and palaeobiology. Previous research has focused exclusively on the energy requirements of adults and highlights the high energy demands of these individuals compared with modern humans. Less attention has been paid to the energy requirements of sub-adult Neandertals, even though this age group could provide clues for a better understanding of Neandertal life history. Accordingly, herein, we estimate the energy costs of maintenance and growth in Neandertal infants and children from one to six years of age and compare these costs with values for modern humans. Statural growth models for two modern human populations (Beasain and Evenki) and an average Neandertal model population are used to establish weight growth models. In turn, these models of body weight growth are used to estimate key components of energetic variables (basal metabolic rate, total energy expenditure, energy of growth and daily energy requirements). Between three and six years of age, Neandertal children have slightly lower basal and growth energy costs than do modern humans of the same age, due primarily to their smaller body mass and slower growth rates. The reduction in energy allocated to growth is likely the result of metabolic adaptations to other somatic factors and thermal stress. Data from contemporary human infants and children suggest that even mild cold stress increases non-shivering thermogenesis, thus elevating metabolic needs by 50% or more. These results suggest that thermal stress likely played a strong role in shaping the delayed developmental patterns and lower energy allocated to growth during early life in Neandertals relative to Homo sapiens., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The high energetic costs of human brain development have been hypothesized to explain distinctive human traits, including exceptionally slow and protracted preadult growth. Although widely assumed to constrain life-history evolution, the metabolic requirements of the growing human brain are unknown. We combined previously collected PET and MRI data to calculate the human brain's glucose use from birth to adulthood, which we compare with body growth rate. We evaluate the strength of brain-body metabolic trade-offs using the ratios of brain glucose uptake to the body's resting metabolic rate (RMR) and daily energy requirements (DER) expressed in glucose-gram equivalents (glucosermr% and glucoseder%). We find that glucosermr% and glucoseder% do not peak at birth (52.5% and 59.8% of RMR, or 35.4% and 38.7% of DER, for males and females, respectively), when relative brain size is largest, but rather in childhood (66.3% and 65.0% of RMR and 43.3% and 43.8% of DER). Body-weight growth (dw/dt) and both glucosermr% and glucoseder% are strongly, inversely related: soon after birth, increases in brain glucose demand are accompanied by proportionate decreases in dw/dt. Ages of peak brain glucose demand and lowest dw/dt co-occur and subsequent developmental declines in brain metabolism are matched by proportionate increases in dw/dt until puberty. The finding that human brain glucose demands peak during childhood, and evidence that brain metabolism and body growth rate covary inversely across development, support the hypothesis that the high costs of human brain development require compensatory slowing of body growth rate.