As a medical anthropologist, Wiley studies the interaction between biology and culture, especially in relation to health, demography, and diet and nutrition using an evolutionary perspective. She has conducted field research in India, working on high-altitude adaptation in the Himalaya, and in Maharashtra, where she and colleagues conducted longitudinal research that investigated the relationship between childhood milk consumption, various biomarkers and growth. Her more recent work focuses on population biological variation in the ability to digest milk after infancy, the life history consequences of milk drinking and the global adoption of milk consumption despite this genetic variability. She is currently working on the concept of "biological normalcy," or how statistical norms for human biological characteristics are related to normative ideas about human biology. She is the author of four books, and numerous articles and book chapters. She has served as the president of the Human Biology Association and is director of the Human Biology Program at IU Bloomington.