My research lies at the intersection of the fields of human biology, behavioral ecology, and evolutionary medicine. I address several questions that are critical to understanding human diversity and the emergence of global health disparities, including:
How do humans allocate metabolic energy between competing life tasks (e.g., reproduction, growth, physical activity, and immune function)?
What roles do biological and social capital play in moderating the energetic effects of physiological and psychosocial stress on phenotype?
How does market integration impact energy use, metabolic plasticity, and the developmental origins of adult disease?
My work draws heavily from anthropology and human evolutionary biology as well as immunology, parasitology, psychology, economics, nutritional/exercise science, and global health. My laboratory research (based on minimally-invasive sample collection methods) includes the development of immune biomarker analyses for use in finger-prick dried blood spot samples, salivary cortisol analysis, fecal gut microbiome analysis, and the application of urine stable isotope analysis (i.e., doubly labeled water) to measure total energy expenditure in the field. This work is performed in the Global Health Biomarkers Lab at the University of Oregon (with Josh Snodgrass) and the Human Evolution and Energetics Lab at Duke University (with Herman Pontzer).
I am currently involved in long-term research projects with three small-scale populations:
The Shuar of Amazonian Ecuador
The Shuar are a large indigenous Amerindian population inhabiting the lowland Amazonas region of southeastern Ecuador. Traditionally forager-horticulturalists living in small, scattered household clusters, they are currently experiencing varying degrees of market integration and lifestyle change. Many Shuar are now living in communities connected by road to larger towns, have electricity, and are engaged in wage labor. Others living in more isolated areas are only beginning to undergo initial stages of modernization and continue to practice a largely traditional way of life. Despite recent development of infrastructure in some regions of their territory, Shuar diet remains generally poor and their burden of infectious disease heavy, particularly among children.
My research among the Shuar is performed as part of The Shuar Health and Life history Project (SHLHP; co-PIs: Dr. Lawrence Sugiyama and Dr. J. Josh Snodgrass of the University of Oregon), a highly collaborative interdisciplinary research effort initiated in Ecuador in 2005. I have been particularly interested in exploring the nature of Shuar childhood growth and its often-complex relationship with market integration, immune activity, and energetics. This work takes advantage of the large dataset of the SHLHP as well as novel longitudinal measures of childhood short-term growth and a diverse panel of immune function biomarkers and state-of-the-art metabolic measures. My research among the Shuar has been funded by the National Science Foundation, the Leakey Foundation, and Harvard University.
The Garisakang are a clan of approximately 500 individuals living in an isolated region of the Middle Ramu River Valley in lowland Papua New Guinea. Members of the Sogerum language group, they are currently concentrated predominantly in a single community and continue to practice a largely traditional subsistence pattern based on small-scale horticulture, foraging, hunting, and fishing. Although several changes among the Garisakang are now taking place (e.g., the first primary school in the region was introduced in 2011), modern infrastructure and integration into the market economy remain minimal. Garisakang social organization is patrilocal with mixed monogamy/polygyny, while demographics are are characterized by universal natural fertility and large realized family sizes.
My research among the Garisakang is carried out as part of the Garisakang Evolutionary Anthropology Project in collaboration with Dr. Martina Konečná (University of South Bohemia, Czech Republic) and the New Guinea Binatang Research Center. Current study is aimed at investigating the biocultural determinants and downstram consequences of psychosocial and physiological stress, with a particular focus on the role of the hormone cortisol in mediating relationships between socioecological variables, phenotypic plasticity, and health. This research is funded by the Czech Science Foundation.
The Maya of the rural Yucatan community of Xculoc are a group of ≈ 500 indigenous Amerindian small-scale agriculturalists. When systematic research was first conducted in Xculoc in 1992, community members were subsistence slash and burn maize farmers with limited access to modern technology and infrastructure. At the time, child domestic and agricultural labor were critical to household economic profiles and patterns of high fertility. Today, the community possesses electricity, running water, a small health clinic, a permanent school, and limited mechanized farming (among other modern features). Despite significant changes, completed fertility remains high.
My research among the Maya is performed in collaboration with Dr. Karen Kramer (project PI; University of Utah). Currently, we are utilizing detailed behavioral and anthropometric data to explore the changes in childhood time allocation, energy expenditure, and growth that accompanying recent modernization and market integration in Xculoc. This research is funded by the National Science Foundation.