Research

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My research lies at the intersection of the fields of human biology, behavioral ecology, and evolutionary medicine. As such, it integrates themes and perspectives from many disciplines, including anthropology, global health, epidemiology, developmental biology, immunology, endocrinology, psychology, economics, and nutritional/exercise science. 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 daily energy expenditure (via doubly labeled water stable isotope tracking), basal metabolism (via respoirometry) and immune 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 questions that are important for understanding human diversity and the emergence of global health disparities, including: 

  1. How do humans allocate metabolic energy between competing life tasks (e.g., reproduction, growth, physical activity, and immune function)? 
  2. How does chronic stress impact metabolism, child development, and health?
  3. How do the lifestyle and environmental changes that accompany market integration alter metabolism and lifetime risk for obesity and chronic disease?
  4. What factors led to the evolution of the unique childhood life stage in humans?  

I currently co-direct long-term and highly collaborative research projects with two Indigenous populations:

 

The Shuar of Amazonian Ecuador 

The Shuar are a large Indigenous population of the Amazonas region of southeastern Ecuador and northeastern Peru. Historically forager-horticulturalists, they are currently experiencing varying degrees of lifestyle change in association with integration into the regional/global market economy. Many Shuar now live in towns or nearby communities, engage in regular wage labor, and practice urban lifestyles. Other Shuar living in more isolated rural areas continue to practice a subsistence-based way of life with limited access to modern infrastructure and healthcare. In these areas, the burden of infectious and parasitic disease is heavy, and childhood growth faltering is common. Troublingly, obesity and chronic diseases (e.g., obesity, hypertension, type-2 diabetes) are also now on the rise among the Shuar, particularly in more market-integrated communities. 

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 am interested in underderstanding how Shuar children manage (and often thrive) in adverse contexts. Much of this work has investigated the complex energetic relationships between children's physical growth, market integration, stress, and immune activity. This research takes advantage of a multi-level, evolutionary life history theory approach and the first measurements of children's energy expenditure in a subsistence-based context. My research among the Shuar has been funded by the National Science Foundation and the Leakey Foundation. See the SHLHP website for a full list of local collaborators. 

Recent Key Publications (see Publications or CV for full list):

Constraint and trade-offs regulate energy expenditure during childhood - Science Advances, Urlacher et al. (2019).

Trade-offs between immune activity and childhood growth among Amazonian forager-horticulturalists - PNAS, Urlacher et al. (2018). 

Heterogeneous effects of market integration on sub-adult body size and nutritional status among the Shuar of Amazonian Ecuador - Annals of Human Biology, Urlacher et al. (2016). 

 

The Garisakang of lowland Papua New Guinea 

The Garisakang are an Indigenous population of approximately 500 individuals living in an isolated river valley in lowland Papua New Guinea. They currently live predominantly in a single community and continue to practice a mixed subsistence pattern based on small-scale horticulture, foraging, hunting, and fishing. Although the Garisakang are experiencing several notable changes (e.g., the first primary school in the region was introduced in 2011), modern infrastructure, healthcare, and integration into the regional/global market economy remain relatively minimal. Garisakang social organization is patrilocal with mixed monogamy/polygyny. Family sizes are large, and the burden of infectious and parasitic disease is, unfortunately, heavy.

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 projects are aimed at investigating the causes and downstream consequences of stress, with a particular focus on the role of the hormone cortisol in mediating energetic relationships between socio-ecological variables, phenotypic plasticity (e.g., child development), and health. This research is funded by the Czech Science Foundation.

Recent Key Publications (see Publications or CV for full list):

Global variation in diurnal cortisol rhythms: Evidence from Garisakang forager-horticulturalists of lowland Papua New Guinea - Stress, Urlacher et al. (2018).

Male social status and its predictors among Garisakang forager-horticulturalists of lowland Papua New Guinea - Evolution and Human Behavior, Konečná and Urlacher (2017). 

Effect of chewing betel nut (Areca catechu) on the measurement of salivary cortisol levels. American Journal of Physical Anthropology, Konečná and Urlacher (2015).