Anthropology, Northwestern University
March 26, 2015 11:00, Grand Ballroom D
Human responses to climatic stressors has long been a focus of research in biological anthropology and environmental physiology. Recently, there has been renewed interest in the study of metabolic adaptation to cold stress as the result of the discovery of active brown adipose tissue (BAT) in adult humans (J Nedergaard et al. 2007. Am J Physiol 293:E444). Current research in nutritional science is examining whether BAT in adults can be stimulated to increase metabolic rates and help prevent or reduce obesity. Yet little attention has been given to larger adaptive/evolutionary questions of whether BAT levels are under selective control and vary with exposure to different climatic conditions. This paper will examine the importance of BAT for human responses to cold challenges throughout the life course, and consider the role that it may play in human adaptations to arctic climates.
Human infants are particularly vulnerable to the effects of cold stress, owing to their small body masses and high surface area to weight ratios. Consequently, BAT plays a critical role in thermoregulation during infancy, with modest cold challenges (~15C) resulting in a doubling of metabolic rates. Among adults, the presence of BAT varies considerably; individuals with significant depots of BAT show 15-20% increases in metabolic rates in response to cold, whereas those without BAT fail to mount a significant thermogenic response. Preliminary research among indigenous Siberian populations suggests that BAT may contribute to both their elevated rates of metabolism and their responses to severe winter-time cold.