Tradeoffs in childhood energy allocation and the impact of market integration on ontogeny and health

社会、行为和经济科学局提供博士后研究奖学金，为新近毕业的博士毕业生提供获得额外培训的机会，在知名科学家的赞助下获得研究经验，并在本科生和研究生培训之外拓宽他们的科学视野。博士后奖学金的进一步设计是为了帮助新科学家引导他们的研究努力跨越传统的学科界限，并利用独特的研究资源、地点和设施，包括在国外。这一博士后奖学金支持一位年轻学者在人类学、进化生物学和公共卫生领域的交叉学科培训和研究，以探索儿童能量分配的权衡和市场经济对健康的影响。儿童管理能量资源和应对不断变化的环境条件的方式仍不清楚。生命的所有基本任务--维持、生长、繁殖、免疫功能和体力活动--都需要能量(即卡路里)，通常认为生物体以最大化健康的方式将资源分配给这些相互竞争的需求。这种能量分配和权衡的框架已经被广泛应用于理解人类的生物变异。然而，很少有研究测试它在儿童中的有效性。针对这一局限，本项目整合了来自多个学科的方法和视角，通过分配权衡的视角调查儿童能源使用的性质。它还应用这一新的综合来探索一个重要的现实世界问题：市场一体化对儿童个体发育和健康的影响。利用在厄瓜多尔亚马孙的Shuar中进行的一项新的研究设计，我们提出了两个主要的研究问题。(1)是否存在能量分配模型所预测的儿童生长、体力活动和免疫功能之间的能量权衡？(2)市场整合是否与儿童能量分配的变化有关，从而导致超重/肥胖和心血管健康状况不佳？研究结果将对几个科学领域产生重大影响。它们还将用于在厄瓜多尔和美国制定有效的卫生政策和救济援助。为了促进培训机会，这项工作涉及许多土著教育健康论坛和为少数族裔美国本科生提供的重要研究经验。重要的是，该项目还为这位研究员提供了科学和专业培训，为他作为综合生物科学前沿的独立研究员的职业生涯做好了准备。尽管之前使用进化生活史理论研究人类生物变异的研究取得了成功，但我们对人类表型可塑性和能源利用的理解仍然存在重大差距。很少有研究调查儿童之间的能量权衡，或者探索体力活动在儿童能量动态中潜在的重要作用。以前的生活史研究没有将总能量消耗(TEE)和静息能量消耗(REE)的准确测量纳入研究设计，从而阻止了对生活史权衡模型的几个关键假设的评估。直接针对这些限制，本项目旨在测试能量权衡模型的有效性，并应用该框架来调查权衡在Shuar市场整合、个体发育和儿童健康之间的关系中的作用。我们在100名舒尔儿童(5-10岁)中采用了一种新的为期两周的纵向研究设计，这些儿童生活在两个社区，在市场整合水平、生活方式和饮食方面存在很大差异。儿童TEE(双标记水)、REE(间接量热法)和体力活动能量消耗(双标记水和加速度计)的金标准代谢测量，以及每周线性增长(关节测量法)、免疫活动(指刺血液C-反应蛋白、总免疫球蛋白E和总免疫球蛋白G)、心血管健康(指刺血糖和血脂)、能量摄入和市场整合(观察和访谈)的稳健测量，支持社区之间、个人之间和个人内部的能量使用和权衡分析。这项工作有能力解决许多未被探索的研究领域，包括超重/肥胖和心血管疾病病因中能量摄入与能量消耗的相对重要性，人类免疫激活的准确能量成本，以及重要的是，生活史权衡模型的整体有效性。

The Directorate of Social, Behavioral and Economic Sciences offers postdoctoral research fellowships to provide opportunities for recent doctoral graduates to obtain additional training, to gain research experience under the sponsorship of established scientists, and to broaden their scientific horizons beyond their undergraduate and graduate training. Postdoctoral fellowships are further designed to assist new scientists to direct their research efforts across traditional disciplinary lines and to avail themselves of unique research resources, sites, and facilities, including at foreign locations. This postdoctoral fellowship award supports the interdisciplinary training and research of a young scholar at the intersection of the fields of anthropology, evolutionary biology, and public health to explore the tradeoffs in childhood energy allocation and the impact of market economy on health. The way in which children manage energetic resources and respond to changing environmental conditions remains unclear. All of life's essential tasks -- maintenance, growth, reproduction, immune function, and physical activity -- require energy (i.e., calories), and it is often assumed that organisms allocate resources to these competing demands in a manner that maximizes fitness. This framework of energy allocation and tradeoffs has been widely applied to understand human biological variation. However, few studies have tested its validity among children. Addressing this limitation, the present project integrates methods and perspectives from multiple disciplines to investigate the nature of childhood energy use through the lens of allocation tradeoffs. It also applies this new synthesis to explore an important real world problem: the impact of market integration on child ontogeny and health. Utilizing a novel study design among the Shuar of Amazonian Ecuador, we pursue two primary research questions. (1) Do energetic tradeoffs exist between childhood growth, physical activity, and immune function as predicted by the energy allocation model? (2) Is market integration associated with changes in childhood energy allocation that promote overweight/obesity and poor cardiovascular health? Results will have significant implications for several scientific areas. They will also be used to develop effective health policy and relief aid in Ecuador and the United States. Promoting opportunity for training, this work involves numerous indigenous educational health forums and significant research experience for minority American undergraduates. Importantly, the project also provides scientific and professional training and for the Fellow, preparing him for a career as an independent researcher at the forefront of integrative biological science.Despite the success of previous studies investigating human biological variation using evolutionary life history theory, important gaps in our understanding of human phenotypic plasticity and energy use remain. Few studies have investigated energetic tradeoffs among children or have explored the potentially important role of physical activity in child energy dynamics. No previous life history research has incorporated accurate measurements of total energy expenditure (TEE) and resting energy expenditure (REE) into study designs, preventing assessment of several critical assumptions of the life history tradeoff model. Directly addressing these limitations, the present project aims to test the validity of the energetic tradeoff model and apply this framework to investigate the role of tradeoffs in relationships between Shuar market integration, ontogeny, and child health. We employ a novel two-week longitudinal study design among 100 Shuar children (age 5-10 years) living in two communities differing greatly in level of market integration, lifestyle, and diet. Gold standard metabolic measures of child TEE (doubly labeled water), REE (indirect calorimetry), and physical activity energy expenditure (doubly labeled water and accelerometry), as well as robust measures of weekly linear growth (knemometry), immune activity (finger-prick blood C-reactive protein, total Immunoglobulin E, and total Immunoglobulin G), cardiovascular health (finger-prick blood glucose and lipids), and energy intake and market integration (observation and interviews) will be made from each participant, supporting between-community, between-individual, and within-individual analyses of energy use and tradeoffs. This work has the ability to address many underexplored areas of research, including the relative importance of energy intake versus energy expenditure in the etiology of overweight/obesity and cardiovascular disease, the precise energetic costs of human immune activation, and, importantly, the overall validity of the life history tradeoff model.