RT Journal Article SR Electronic T1 Constraint and trade-offs regulate energy expenditure during childhood JF Science Advances JO Sci Adv FD American Association for the Advancement of Science SP eaax1065 DO 10.1126/sciadv.aax1065 VO 5 IS 12 A1 Urlacher, Samuel S. A1 Snodgrass, J. Josh A1 Dugas, Lara R. A1 Sugiyama, Lawrence S. A1 Liebert, Melissa A. A1 Joyce, Cara J. A1 Pontzer, Herman YR 2019 UL http://advances.sciencemag.org/content/5/12/eaax1065.abstract AB Children’s metabolic energy expenditure is central to evolutionary and epidemiological frameworks for understanding variation in human phenotype and health. Nonetheless, the impact of a physically active lifestyle and heavy burden of infectious disease on child metabolism remains unclear. Using energetic, activity, and biomarker measures, we show that Shuar forager-horticulturalist children of Amazonian Ecuador are ~25% more physically active and, in association with immune activity, have ~20% greater resting energy expenditure than children from industrial populations. Despite these differences, Shuar children’s total daily energy expenditure, measured using doubly labeled water, is indistinguishable from industrialized counterparts. Trade-offs in energy allocation between competing physiological tasks, within a constrained energy budget, appear to shape childhood phenotypic variation (e.g., patterns of growth). These trade-offs may contribute to the lifetime obesity and metabolic health disparities that emerge during rapid economic development.