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Objective: This work aimed to parse out the role of changing environments on body composition, total energy expenditure, and physical activity in the Mexican Pima, a population experiencing rapid industrialization. Methods: Using doubly labeled water, we compared energy expenditure and physical activity in a longitudinal cohort of Mexican Pima (n = 26; female: 12) in 1995 and 2010. Body mass and composition were assessed by bioimpedance analysis. To determine the effects of environmental factors on body weight independent of age, we compared the 1995 longitudinal cohort with an age‐ and sex‐matched cross‐sectional cohort (n = 26) in 2010. Results: Body mass, fat mass, and fat‐free mass all significantly increased between 1995 and 2010. Despite a 13% average increase in body weight, weight‐adjusted total daily energy expenditure decreased significantly. Measured physical activity levels also decreased between 1995 and 2010, after we adjusted for weight. Conclusions: Our results suggest that the recent industrialization of the Maycoba region in Sonora, Mexico, has contributed to a decrease in physical activity, in turn contributing to weight gain and metabolic disease among the Mexican Pima. [ABSTRACT FROM AUTHOR]

Objectives: Despite the growing rates of global obesity and the known positive associations between brown adipose tissue (BAT) and cardiovascular health, little is known about the metabolic effects of BAT activity in Samoans, a population at high risk of obesity and type II diabetes. Here we assessed the potential effects of inferred BAT activity on metabolic health markers in Samoan adults exposed to mild cold. Methods: Using point‐of‐care finger prick technology we measured fasting glucose, total cholesterol, high‐density lipoprotein (HDL), and low‐density lipoprotein (LDL) levels before and after 30 min of cold exposure among 61 individuals (38 females, 23 males, ages 31–54) from 'Upolu Island, Samoa. Respiratory quotient was measured by indirect calorimetry to determine substrate metabolism at room temperature and cold exposure. Results: Fasting glucose levels decreased significantly (p <.001) after cold exposure while neither total cholesterol (p =.88), HDL (p =.312), nor LDL (p =.089) changed. Respiratory quotient decreased significantly (p =.009) between exposures, suggesting an increased preference for lipid metabolism as a response to cold. Conclusions: The observed effects of inferred BAT activity on biomarkers suggest BAT activity utilizes both glucose and lipid‐derived fatty acids as fuel for thermogenesis. Our work provides evidence for the beneficial metabolic effects of BAT and emphasizes the need for the population‐specific development of metabolic treatments involving BAT to ensure the successful and equitable minimization of extreme consequences of obesity and metabolic health. [ABSTRACT FROM AUTHOR]

Objectives: A hallmark of the human species is our adaptability to a wide range of different ecologies and ecosystems, including some of the most extreme settings. Human biologists have long studied how humans have successfully (and sometimes unsuccessfully) adapted to such extremes, particularly ecological extremes like environments at lower limits of temperature and high altitude. In this special issue, we revisit traditional definitions and explore new conceptions of work in extreme environments. We argue that our definitions of extremes should change with our changing world, and account for extremes unique to the Anthropocene, including environments of inequality and precarity, pandemic landscapes, climate‐impacted settings, obesogenic environments, and the environments of human spaceflight. We also explore the future of work at the extremes and provide some suggested guidelines on how human biologists can continue to build and expand on foundational work in this area. Conclusion: While human biologists have done critical work on groups living in extreme environments, our definitions of humans at the limits continue to change as the world around us also changes. Scholars in this area have a responsibility to re‐examine the parameters of extremes to stay at the forefront of scientific exploration and collaboration so human biology, as a discipline, can continue to shape our understanding of adaptability, and thus contribute to the continued thriving of all humans as we endure new climatic, environmental, and societal extremes. [ABSTRACT FROM AUTHOR]

Objectives: Brown adipose tissue (BAT) is a heat‐producing organ aiding nonshivering thermogenesis (NST) during cold stress. Due to its potential cold‐adaptive role BAT has been predominantly studied in cold and temperate climate populations, but not among warm‐climate adults. This work explores if BAT activity can be inferred in Samoans. Materials and Methods: We inferred BAT activity by comparing metabolic rate and surface heat dissipation using indirect calorimetry and thermal imaging between room temperature and cold exposure among Samoans (N = 61, females: n = 38) from 'Upolu Island, Samoa. BAT activity was inferred using ANOVA linear regression models with the variables measured at cold exposure as outcomes. T‐tests were used to compare changes in surface temperature between room temperature and cold exposure. Results: Metabolic rate significantly increased after cooling. In both the supraclavicular area, a known BAT location, and the sternum, a non‐BAT location, temperatures decreased significantly upon cold exposure. Differences in supraclavicular temperatures between room temperature and cold were significantly smaller than differences in sternum temperatures between exposures. These results suggest that BAT thermogenesis occurred in known BAT‐locations and thus contributed to NST during cooling. Conclusions: This study adds to our understanding of BAT activity across different populations and climates. Further study may illuminate whether the cold‐adaptive properties of BAT may have played a role in the successful expansion of populations across the globe, including warm‐climate groups. [ABSTRACT FROM AUTHOR]

Prehistoric colonization of East Polynesia represents the last and most extensive of human migrations into regions previously uninhabited. Although much of East Polynesia is tropical, the southern third, dominated by New Zealand—by far the largest Polynesian landmass—ranges from a warm- to cool-temperate climate with some islands extending into the Subantarctic. The substantial latitudinal variation implies questions about biocultural adaptations of tropical people to conditions in which most of their familiar resources were absent and their agriculture marginal. Perhaps the most basic question, but one which has never been explored, is the extent to which sailing out of the tropics on long-distance colonizing voyages imposed physiological stress on canoe crews and passengers. In this paper we use trajectories of simulated voyages from Tahiti to New Zealand and Tahiti to Hawaii to obtain along-trip environmental parameters which are then used to model the energy expenditure of these long overseas journeys. Results show that travelers to New Zealand are exposed to much harsher environmental conditions, leading to significantly greater in-trip thermoregulatory demands. For both destinations, travelers with larger body sizes exhibit lower modeled heat loss and hence obtain an energetic advantage, with greater gains for females. Such physiological features, notably of Samoans who probably formed the founding population in East Polynesia, may help explain successful voyaging to temperate latitudes. [ABSTRACT FROM AUTHOR]

Objectives: We investigated seasonal changes in brown adipose tissue (BAT) activation and metabolism in a temperate‐climate Albany, NY population. Methods: Data were collected among 58 participants (21 males, 37 females, ages: 18–51) in the summer and 59 participants (23 males, 36 females, ages: 18–63) in the winter in Albany, New York. BAT activity was inferred by comparing metabolic rate, heat dissipation in the supraclavicular area, and respiratory quotient at room temperature and cold exposure. Seasonal variation in BAT was determined by comparing these measurements from summer and winter. Results: At mild cold exposure, heat dissipation of the supraclavicular area was significantly greater in the winter compared to summer (p <.001); however, no significant differences were found between seasons in metabolic rate measurements. This suggests BAT activation may be metabolically more efficient in the winter, due to prolonged lower seasonal temperatures relative to summer. Respiratory quotient significantly increased upon mild cold exposure in the winter compared to summer (p <.001). While carbohydrate utilization increased in the winter, fat remained the primary metabolic substrate for BAT activity across both seasons. Conclusion: The seasonal variations in the effects of nonshivering thermogenesis on metabolic rate and substrate metabolism suggest a buffering of energy expenditure and an increased use of glucose as fuel by BAT as a result of acclimatization to cold in the winter. These findings point towards a potential role of BAT in human whole‐body mediated glucose disposal and cold adaptation. [ABSTRACT FROM AUTHOR]

Background: Quality mentorship is crucial for long‐term success in academia and overall job satisfaction. Unfortunately, formal mentorship training is lacking, and there is little recourse for failed mentor–mentee relationships. Methods: We performed a literature review to understand the current state of mentorship research with a focus on: (1) what mentorship is and why it is important for success; (2) establishing mentor‐mentee relationships; and (3) the role of diversity, equity, and inclusion. Results: From the literature review, we compiled a number of mentorship recommendations for individuals, departments, institutions, and professional associations. These recommendations focus on building a mentorship network, establishing formalized mentorship training, how to build a productive and mutually beneficial mentor–mentee relationship, and instituting a system of mentorship accountability. Conclusion: We hope that by centralizing this information and providing a list of resources and actionable recommendations we inspire and encourage others to make meaningful changes in their approach to mentorship to create a more kind, caring, and equitable environment in which to conduct our work. [ABSTRACT FROM AUTHOR]

A large body of work focuses on the unique aspects of Neanderthal anatomy, inferred physiology, and behavior to test the assumption that Neanderthals were hyper‐adapted to living in cold environments. This research has expanded over the years to include previously unexplored and potentially adaptive features such as brown adipose tissue and fire‐usage. Here we review the current state of knowledge of Neanderthal cold adaptations along morphological, physiological, and behavioral lines. While highlighting foundational as well as recent work, we also emphasize key areas for future research. Despite thriving in a variety of climates, it is well‐accepted that Neanderthals appear to be the most cold‐adapted of known fossil hominin groups; however, there are still many unknowns. There is a great deal yet to be uncovered about the nature and manifestation of Neanderthal adaptation and how the synergy of biology and culture helped buffer them against extreme and variable environments. [ABSTRACT FROM AUTHOR]