Michael Muehlenbein

Michael Muehlenbein

Faculty, International Studies


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Research interests

My 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. Part of this involves characterizing hormone-mediated trade-offs between the immune and reproductive systems, using life history theory to explain the evolutionary bases for these trade-offs, and developing theoretical and empirical models so as to cultivate an explanatory framework for differential susceptibility to infectious diseases, specifically parasites and viruses.

Infectious diseases have been important selection pressures instrumental in the evolution of human and non-human primates, and mammalian immunity has evolved into a complex system of components whose proper performance is influenced by many physiological systems, including reproductive hormones of the endocrine system. Interestingly, an evolutionary perspective can contribute valuably to medical research and practices, including basic aspects of immunology and endocrinology. As predicted by evolutionary and life history theories, testosterone variation within an individual should function as an adaptive mechanism to augment reproductive effort or bolster immunity according to available energy and disease risk in the environment. Because testosterone modulates immune, reproductive, and somatic metabolic functions, assessing interactions between testosterone, measures of metabolism, and immune factors during infection are insightful for understanding male physiological ecology and the optimization of hormone levels under various environmental conditions.

The second major aspect of my research involves assessment of primate disease ecology with the ultimate purpose to describing zoonotic transmission potential between human and non-human primate populations. Human encroachment into previously un-impacted forest is believed to be partly responsible for various emerging infectious diseases, specifically hemorrhagic fevers. Encroachment into these areas can facilitate disease transmission from animal to human not only through increased initial contact between the two, but also from elevated population densities of animals confined to smaller tracks of forest. At my fieldsite in Sabah, Malaysia ( Island of Borneo), human contact with wild orang-utans and other species is increasing through population growth of the indigenous peoples, increases in tourism, and most dramatically, by encroachment from oil-palm plantations and their workers. My goal is to assess potential negative effects of increased human-animal contact through the long-term collection of samples from local villagers, oil-palm plantation employees, orangutans, and even elephants. I have also conducted parasitological analyses on wild chimpanzee, sifaka, baboon, and vervet populations in the past.


Muehlenbein MP (2010)(ed.). Human Evolutionary Biology. Cambridge University Press. Forthcoming.

Muehlenbein MP. 2006. Intestinal parasite infections and fecal steroid levels in wild chimpanzees. American Journal of Physical Anthropology 130:546-550.

Muehlenbein MP, Cogswell F, James M, Koterski J, Ludwig G. 2006. Testosterone correlates with Venezuelan Equine Encephalitis virus infection in macaques. Virology Journal 3:19-27.