Animals utilize a variety of ornamentations or signals, including coloration, to attract the attention of potential mates. Such condition-dependent signals may reveal current health status and thus reflect genetic resistance to pathogens. In fact, signal expression is related to immune status in a number of species investigated to date. However, the relationships between "honest" indicators of quality and immunity have not been adequately evaluated in primates. Despite this fact, much work in primatology and human evolutionary biology is based on assumptions that these signals are indicative of immunity, and that they are related in complex ways to hormone levels. To evaluate these assumptions, a team of scholars with combined expertise will measure body condition, behavior, endocrine function, and immune function in 150 adult male and 150 adult female rhesus macaques (Macaca mulatta), each sampled during breeding and non-breeding seasons at the Tulane National Primate Research Center. It is hypothesized that sex skin coloration is an honest indicator of robust immunocompetence, and that both coloration and immunocompetence are modulated in part by the functions of various hormones.
Investigating the immunomodulatory actions of hormones allows greater understanding of the evolutionary significance of immune-endocrine interactions and provides a unique life-historical perspective on mammalian immune function. Research to clarify these interactions in nonhuman primates will provide a valuable comparative and evolutionary perspective to selection in our own species. The project also offers valuable training opportunities to graduate, undergraduate and high school students of diverse backgrounds to become members of a collaborative research community and learn sophisticated laboratory techniques and their applications. Another important applied aspect of this project includes the organization of a workshop on biomarkers in evolutionary anthropology. Future project development will include additional hormone and genetic analyses in remaining samples collected and stored from the current project.