An evolutionary anthropological perspective on clinical endocrinology and immunology
Immunity is an integral part of organismal life histories because it is crucial for maximizing evolutionary fitness and because it is energetically expensive to develop, maintain, and activate. In this presentation I will describe the roles of immunity in human life history trade-offs, specifically the utility of hormones in mediating variation in immunity. Hormones are central mechanisms that contribute to the onset and timing of key life history events, the optimal allocation of time and energy between competing functions, and the general modulation of phenotypic and genotypic expression. I will describe the roles of testosterone, dehydroepiandrosterone and estradiol in moderating immunocompetence from a life history perspective, illustrating how correlated changes in immunity and gonadal function reflect the manifold interactions between these two systems. The immunomodulatory actions of these hormones are complex and varied, and I attempt to provide explanations for this variation in the literature. Although evidence comes from clinical medicine, my basic prediction is derived from life history theory: altering the hormonal milieu may result in differential susceptibility to both infectious and chronic diseases. The immunological costs associated with hormone supplementation are worthy of greater consideration by both clinical practitioners and evolutionary ecologists alike.
Michael Muehlenbein is an Assistant Professor in the department of Anthropology at Indiana University. His research interests are focused primarily on various aspects of the biology and ecology of infectious diseases, including the human and non-human primate physiological adaptations to these diseases as well as the impact of environmental change on zoonotic disease transmission potential, specifically between human and non-human primate populations.