Childhood is a unique and developmentally critical life stage within the human genus. While theory concerning the evolution of the human life cycle now abounds, biocultural data from traditional, non-industrialized populations are scarce, and relatively little is known about how children in such challenging environments behave, respond to environmental stimuli, or manage limited energetic resources. This study by doctoral student Samuel Urlacher (Harvard), under the guidance of Dr. Peter Ellison, builds upon scholarship in diverse areas of anthropology, biology, and public health to address two questions that are critical to our understanding of human life history and adaptation: 1) How is childhood growth related to the function of the immune system? 2) How do children 'buffer' energetic tradeoffs between competing metabolic demands? To investigate these questions, this research operationalizes hypotheses relating to childhood energy allocation and phenotypic plasticity among the traditional-living Shuar of the Ecuadorian Amazon.
Innovative in design, the project involves longitudinal data collection for measures of short-term linear growth, body composition, physical activity/behavior, and a diverse set of biomarkers of immune function with children age 5-10. This study is unique in its ability to control for differences in individual biology and is the first to consider multiple branches of immunity and physical activity as important variables in childhood energy management. Employing a novel method for short-term growth assessment (knemometry), the research also provides insight into previously unexplored relationships between primary human life functions and acute ecological/energetic variables.
In addition to increasing our broad-based understanding of human health, adaptation, and the importance of energy management in the evolution of childhood, the project has implications for multiple areas of research and application to issues of childhood development and well-being on a global scale. As part of the Shuar Health and Life History Project, this research builds on a strong foundation of international collaboration and community outreach. Results from the study are shared with Ecuadorian officials and will directly influence the development of health policy and the targeting of humanitarian aid in Shuar territory. Essential to any research with at-risk populations, the project also shares information with participants' families and delivers basic health education at the community level.
