Since leaving graduate school in 1974, the author has pursued biomedical research, first as part of a Nobel Prize-winning team at Scripps Clinic and Research Foundation, and since 1984 in the Department of Microbiology, Immunology, and Pathology at Colorado State University. All of this research focuses on the workings of human immune and nervous systems and the nature of human selves. In 2004, in recognition of his literary contributions to popular scientific literature, Dr. Callahan received a joint appointment in the Department of English at CSU and between 2011 and 2013 served as the director of the Graduate Creative Nonfiction program in that department. During his career, he has published more than 50 scientific papers in respected scientific journals and more than 70 poems and essays in literary journals as well as four popular-science books. He has received numerous awards for his science, his writing, and his teaching. These include three National Research Service Awards, designation as a Leukemia Society of America Scholar, a Colorado Council on the Arts Fellowship, nomination for a Pulitzer Prize, and the Outstanding Science Faculty Award in 2012. Because of his literary accomplishments, Dr. Callahan is also the Director of the Creative Nonfiction Graduate Program in the Department of English at CSU. Dr. Callahan and his work have been featured in or on, 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, USA 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.