Dr. Callahan writes about science for general audiences and holds a joint appointment in the department of English. He investigates interactions between the human immune and nervous systems, humans and their microbiomes, and the biological basis of sex. His work has been featured on or in, among others, National Geographic Television, ABC evening News, the Los Angeles Times, Salon.com, the Chicago Tribune, National Public Radio, Minnesota Public Radio, Talk Radio Europe – Spain, Ms. Magazine, the New Scientist, Discover Magazine, U.S.A. Today, the Vancouver Sun, the Canadian Broadcasting Corporation, Georgia Straight, the Rocky Mountain News, ESPN, Publisher’s Weekly, Semana Magazine – Columbia, and EPOCA magazine – Brazil. His works have been translated into Japanese, Chinese, and Portuguese. Currently, Dr. Callahan is teaching the Construction of Self in Philosophy, Literature, and Medicine Honors seminar.