Theresa Elizabeth Gildner

Grant Type

Dissertation Fieldwork Grant

Institutional Affiliation

Oregon, U. of

Grant number

Gr. 9231

Approve Date

April 8, 2016

Project Title

Gildner, Theresa E., U. of Oregon, Eugene, OR - To aid research on 'Life History Tradeoffs Between Testosterone and Immune Function: Testing the Immunocompetence Handicap Hypothesis,' supervised by Dr. J.Josh Snodgrass

Preliminary abstract: This research uses a biocultural approach and anthropological methods to test predicted life history tradeoffs between reproductive effort (measured using testosterone levels and phenotypic masculine traits) and immune function among the Shuar of Ecuador, a forager-horticulturalist group characterized by high parasite load. Human Life History Theory aims to understand how natural selection produces age and context-dependent tradeoffs in resource allocation to different biological functions, and the physiological bases of these allocations and their outcomes. Still, predicted energetic tradeoffs between mating effort and immune function remains poorly tested among contemporary human populations. Debate remains, for example, about the degree to which intra- versus inter-sexual selection have shaped tradeoffs between immunocompetence and the development and maintenance of secondary sexual characteristics (e.g., through the effects of sex hormones like testosterone). Furthermore, to date, no study has examined the relationship between testosterone and immune function in a natural fertility, high pathogen environment (like the Shuar) reflecting conditions more similar to past human populations under which these hypothesized tradeoffs evolved. This project is the first population-based study to test if there is a direct relationship between testosterone profile and parasite load among an indigenous population. The results of this study will provide insights useful for assessing the validity of hypotheses dependent on these data, such as the hypothesis that inter-sexual selection produced female assessment and preference for testosterone-linked masculine traits as an honest signal of male quality because of the immunosuppressant effects of testosterone.