My research lies at the intersection of the fields of human biology, behavioral ecology, and evolutionary medicine. As such, it integrates themes from diverse areas, including global health, epidemiology, developmental biology, immunology, endocrinology, psychology, economics, nutritional/exercise science, and elsewhere. This interdisciplinary approach is critical to my work.
The Human Evolutionary Biology and Health Lab that I direct at Baylor – housed in the state-of-the-art BSL2+ Anthropology Core Lab – specializes in the measurement of total daily energy expenditure (via doubly labeled water stable isotope analysis), basal metabolism (via indirect calorimetry) and immune/growth biomarkers and hormones (via ELISA and other methods). This includes the development of new analyses for use in minimally invasive finger-prick dried blood spot samples.
I address several questions that are important for 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 stress on phenotype?
How does market integration impact energy use, metabolic plasticity, and the developmental origins of obesity and adult disease?
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. Historically forager-horticulturalists living in small, scattered households, they are currently experiencing varied degrees of market integration and lifestyle change. Many Shuar now live in communities connected by road to large towns, have electricity, receive formal education, and engage in wage labor. Others living in more isolated areas continue to practice a largely subsistence-based way of life. Despite recent development of infrastructure in some areas, Shuar diet remains generally inadequate. Their burden of infectious and parasitic disease is heavy, particularly among children.
My research among the Shuar is performed as part of The Shuar Health and Life history Project (SHLHP; co-director), a highly collaborative interdisciplinary research effort initiated in Ecuador in 2005. I have been particularly interested in investigating the nature of Shuar childhood growth and its 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, immune function biomarkers, and direct metabolic measures. My research among the Shuar has been externally funded by the National Science Foundation and the Leakey Foundation.
The Garisakang are an indigenous population of approximately 500 individuals living in an isolated section of the Middle Ramu River Valley in lowland Papua New Guinea. Members of the Sogerum language group, they currently live predominantly in a single community. They continue to practice a mixed subsistence pattern based on small-scale horticulture, foraging, hunting, and fishing. Although the Garisakang are experiencing a number of important changes (e.g., the first primary school in the region was introduced in 2011), modern infrastructure and integration into the market economy remain relatively minimal. Garisakang social organization is patrilocal with mixed monogamy/polygyny. Demographics are characterized by universal natural fertility and large realized family sizes. Adoption is common.
My research among the Garisakang is carried out as part of the Garisakang Evolutionary Anthropology Project (GEAP; co-director) in collaboration with Dr. Martina Konečná (University of South Bohemia, Czech Republic) and the New Guinea Binatang Research Center. Current research is aimed at investigating the biocultural determinants and downstream 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.