This dissertation explores how the environment shapes energy expenditure and cardio-metabolic disease risk by investigating multiple timescales of adaptation to cold stress among the Yakut, an indigenous circumpolar population. This study pursues three main objectives. First, the adaptive and health significance of brown adipose tissue (BAT) is explored by examining its role in homeostatic responses to cold stress among Yakut adults. Second, this project examines evidence for seasonal acclimatization to a cold climate via changes in thyroid hormone dynamics. Third, the study analyzes evidence for developmental adaptation in BAT thermogenesis and discusses the timing of critical periods and their significance for understanding phenotypic plasticity.The results of this dissertation demonstrate that BAT may play an important role in metabolic adaptation to acute exposure to low temperatures, and influences the metabolism of carbohydrates and lipids and energy balance. Yakut men and women exhibit seasonal shifts in thyroid hormone levels indicative of the “polar T3 response”. Seasonal changes in thyroid hormones are structured by lifestyle such that men with greater subsistence activity participation exhibited larger reductions in thyroid hormone levels. Finally, the results provide the first evidence for developmental plasticity in BAT in humans and indicate that critical periods for plasticity in metabolism may extend into childhood and puberty. The results of this project highlight the critical role that the environment plays in shaping energy budgets. Furthermore, this dissertation emphasizes that the avenues through which the environment alters an individual’s metabolism will depend on the interaction of the specific social, economic, cultural and ecological characteristics the person’s environment. In order to better understand the ways in which the environment alters energy budgets and health, the timescale of the environmental stressor and the timescale of the sensitive biological mechanisms should be considered. Finally, the results of this dissertation have important implications for cardio-metabolic disease risk within the context of lifestyle change and global climate change

Last modified

• 01/09/2019

Creator

• Stephanie B Levy

DOI

• https://doi.org/10.21985/N2R45M

Subject

• Anthropology

Keyword

• Anthropology

Date created

• 2017-01-01

Resource type

• Dissertation

Rights statement

• In Copyright